NC-2009 EAp2: Minimum Energy Performance

  • NC EAp2 Credit Req's Diagram
  • Beyond code compliance, but doable

    This prerequisite is a big one, not only because it’s required for all projects, but also because it feeds directly into EAc1: Optimize Energy Performance, where about a fifth of the total available points in LEED are at stake. Master these minimum requirements, and you can use the same compliance path as in EAp2 to earning points.

    You won’t earn the prerequisite by accident, though. Although “energy efficiency” is on everyone’s lips, the mandatory and performance-based requirements for EAp2 go beyond code compliance in most places. That said, there is nothing to stop you from meeting the requirements with a reasonable amount of effort, and the environmental benefits as well as the operational cost savings are significant.

    Most projects start by choosing which of the three available compliance paths to follow. We’ll look at them each in turn.

    Option 1: Energy modeling

    Option 1 alone gives you access to all of the points available through EAc1, and offers the most flexibility in giving you credit for innovative designs.

    First, you need to meet the mandatory requirements of ASHRAE 90.1-2007 for all major components, including the envelope, HVAC, lighting, and domestic hot water. ASHRAE 90.1 has had some changes and new mandatory requirements since the 2004 version, which was referenced on previous LEED systems, so be sure to review the standard carefully.

    Cost of changeEnergy efficiency is an area where it behooves project teams to start early and work together to maximize savings. Playing catch-up later on can be costly.Second, you need to demonstrate a 10% savings (5% for existing buildings) for your designed building compared with a baseline case meeting the minimum requirements of ASHRAE 90.1 (or Title 24-2005, Part 6 for California projects). You do this by creating a computer model following rules described in Appendix G of ASHRAE 90.1.

    Computer modeling offers the following key advantages:

    • It can be used to provide feedback on your design both early on, and as the design progresses, so it’s best to use in this way rather than simply demonstrating compliance.
    • It can help your team focus on the most cost-effective efficiency strategies, by plugging in different options and seeing the results.
    • If your building is unconventional or complex in design, an energy model is the best way to account for that.

    Your building type may not have a choice—you may have to follow this path, because both Options 2 and 3 are prescriptive compliance paths that are only available to specific building types and sizes.

    However, if your building type and size allow, and you don’t want to embark on the complex process of computer modeling, which also requires expert assistance from a modeler or from a member of the mechanical engineer’s team, the prescriptive compliance paths are a good way to earn the prerequisite simply by following a checklist.

    Solar shadingPassive design strategies such as shading to reduce solar heat gain are the most cost-effective ways to improve energy performance.Note, however, that when you get to EAc1, there are a lot fewer points on the table for the prescriptive paths, and that you have to follow each prescriptive requirement. These paths also require more collaboration and focus early on in design than you might think. The design team must work together to integrate all of the prescriptive requirements, and Option 3 even requires documentation of certain design processes.

    Option 2: ASHRAE Advanced Energy Design Guides

    The Advanced Energy Design Guides are published by ASHRAE for office, warehouse, and retail projects less than 20,000 ft2—so if you don’t fall into one of those categories, you’re not eligible for this path.

    These guides outline strategies to reduce energy use by 30% from 2001 levels, or an amount equivalent to approximately 10%–14% reduction from ASHRAE 90.1-2007. If you choose this compliance path, become familiar with the list of prescriptive requirements and commit to meeting all of them.

    Option 3: Advanced Buildings Core Performance Guide

    The Core Performance Guide path is a good option if all of the following are true:

    • your project is smaller than 100,000 ft2,
    • you cannot pursue Option 2 because there is not an ASHRAE guide for the building type,
    • your project is not a healthcare facility, lab, or warehouse,
    • and you would rather not commit to the energy modeling required for Option 1.

    Comply with all requirements within Sections 1 and 2 of the guide. If you choose this path, become familiar with the list of prescriptive requirements and commit to meeting them. Also note that it’s not just a list of prescriptive requirements, but a prescribed process for achieving energy efficiency goals. You must demonstrate that you considered a couple of alternate designs, for example, and that certain team meetings were held.

    Reduce energy loads first

    Energy efficiency offers a clear combination of environmental benefit and benefit to the owner through reduced operational expenses, and potentially reduced first costs, if you’re able to reduce the size and complexity of your HVAC system with a more efficient envelope.

    High-tech HVAC systems, and onsite renewable energy generation are often signature components of green buildings, but consider these strategies more “icing” on the cake, rather than a place to start. Start with building orientation and passive design features first. Also look at envelope design, such as energy-efficient windows, walls and roof, before looking at HVAC and plug loads. A poorly designed envelope with a high-tech HVAC system is not, on the whole, efficient or cost-effective. 

    District energy systems

    Projects connected to district energy systems will not be able to utilize the system efficiencies of the base plant to demonstrate compliance with the prerequisite. They can plan on benefiting from these systems under EAc1, however.

    Look for incentives

    Focusing on energy efficiency and renewable energy generation can seem to add costs to a project, but there are a variety of utility-provided, as well as state, and federal incentives available to offset those premiums. (See Resources.)

  • FAQs for EAp2

    Is it acceptable to model a split-type AC with inverter technology compressor as a heat pump, like modeling VRF?

    Ideally if the software you are using cannot model a technology directly then seek a published workaround related to your software. If you can't find a published workaround then model it as you think it should be modeled and explain how you have modeled it in the preliminary LEED submission.

    A portion of our building envelope is historic. Can we exclude it from our model?

    No, not if it is part of the LEED project. However, there is an exemption for existing building envelopes in Appendix G that allow you to model the existing condition in the baseline so you do not pay a penalty.

    For an existing building, do I need to rotate the model?

    No, not for an existing building.

    Our project has a large process load—75%. Despite our efforts to make an efficient HVAC design, the cost savings are minimal. What can we do to earn this prerequisite and be eligible for LEED certification? Is there any flexibility in how we model the process load?

    You must model accurately. Since you don't have enough savings in the building energy, find savings in the process. Either you will be able to demonstrate that compared to a conventional baseline the process being installed into the factory is demonstrably better than "similar newly constructed facilities," allowing you to claim some savings, or the owner needs to install some energy-saving measures into the process to get the project the rest of the way there. Either option can be difficult, but not impossible.

    Account for process load reductions through the exceptional calculation method. A baseline must be established based on standard practice for the process in your location. Any claim of energy savings needs a thorough narrative explaining the baseline and the strategy for energy savings along with an explanation of how the savings were calculated.

    Our process load is higher than 25%. Do we have to justify that?

    It is common to have a 80%–90% process load in a manufacturing facility. The 25% default in LEED is based on office buildings. If you think your load is lower than 25%, it is recommended that you explain why in a short narrative. It is also recommended to briefly explain it if your load is 25% exactly, since that level commonly reveals that the process loads were not accurately represented.

    Do the required savings for this prerequisite (and credit) need to come only from building energy, or also process loads?

    The energy savings are based on the whole building energy use—building and process. LEED does not stipulate exactly where they come from.

    Our local code references ASHRAE 90.1-2010. Should I use that for my documentation, or 90.1-2007?

    For LEED 2009 you'll need touse 90.1-2007. There were some significant changes in 90.1-2010—too many to account for in your LEED review, and your project would also have a much harder time demonstrating the same percentage energy savings.

    Our project doesn't have enough energy savings to earn the prerequisite. Can we get there by incorporating onsite renewables?

    Yes according to LEED, although it is not recommended as a best practice, and it is usually more cost-effective to invest in energy savings in the building.

    Can I claim exterior lighting savings for canopy lighting even though a baseline model cannot include shading elements?

    You can assume exterior lighting savings for canopies against the baseline, but not the shading effects of canopies.

    The project is built on a site with existing exterior lighting installed. How should this be accounted for?

    If exterior lighting is present on the project site, consider it as a constant in both energy model cases.

    Can mezzanines open to floors below be excluded from the energy model?

    Any conditioned area must be included in the energy model.

    How do I provide a zip code for an international location?

    The Energy Star portion of the form does not apply to international projects.

    For a project outside the U.S., how do I determine the climate zone?

    Use the tables and definitions provided in 90.1 Appendix B to determine an equivalent ASHRAE climate zone.

    For a project outside the U.S., how do I determine the Target Finder score?

    International projects are not required to enter a Target Finder score. Target Finder is based on U.S. energy use data.

    Do hotel rooms need automatic light shut-off control?

    For Section 9.4.1.1c, a manual control device would be sufficient to comply with mandatory provisions.

    How commonly are the 90.1 mandatory compliance forms submitted as part of EAp2/EAc1?

    Submitting these forms is not common; however, it can be beneficial if you are applying for any exceptions.

    The Section 9 space-by-space method does not include residential space types. What should I use?

    Use the building area method.

    Can the Passive House Planning Package (PHPP) be used to energy model for LEED?

    Although there is no formal list of approved simulation tools, there are a few requirements per G2.2.1, including the ability of the program to provide hourly simulation for 8760 hours per year, and model ten or more thermal zones, which PHPP does not meet.

    Can the Trace 700 'LEED Energy Performance Summary Report' by uploaded to LEED Online in lieu of the Section 1.4 tables spreadsheet?

    The automated Trace 700 report provides less information than is requested by the Section 1.4 tables spreadsheet. The Section 1.4 tables spreadsheet must be completed.

    Which baseline HVAC system do I use if my building has no heating or air conditioning?

    Assign HVAC systems as per Appendix-G and Section 6 but set thermostatic setpointsSetpoints are normal operating ranges for building systems and indoor environmental quality. When the building systems are outside of their normal operating range, action is taken by the building operator or automation system. out of range so that systems never turn on.

    Our project has a diesel backup generator. Should we include it in our energy model?

    If it is only used for backup and not for regular use such as peak shaving—no.

    Can SHGC be higher in the proposed than in the baseline model?

    SHGC is not a mandatory provision so it is available for trade-off and can be higher than the baseline.

    Do I need to justify the electrical and fuel rates I am using in my model?

    You generally wouldn't need to upload any documentation, but particularly for a non-U.S. project, it may help to provide a short narrative about what they are based on.

Legend

  • Best Practices
  • Gotcha
  • Action Steps
  • Cost Tip

Pre-Design

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  • Discuss your project’s energy performance objectives, along with how those are shaping design decisions, with the owner. Record energy targets in the Owners Project Requirements (OPR) for the commissioning credits EAp1 and EAc3


  • You won’t earn this prerequisite by accident. The energy efficiency requirements here are typically much more stringent than local codes, so plan on giving it special attention with your team, including leadership from the owner. 


  • Consider stating goals in terms of minimum efficiency levels and specific payback periods. For example: “Our goal is to exceed a 20% reduction from ASHRAE 90.1, with all efficiency measures having a payback period of 10 years or less.”


  • Develop a precedent for energy targets by conducting research on similar building types and using the EPA’s Target Finder program. (See Resources.)


  • For Option 1 only, you will need to comply with the mandatory requirements of ASHRAE 90.1-2007, to bring your project to the minimum level of performance. The ASHRAE 90.1-2007 User’s Manual is a great resource, with illustrated examples of solutions for meeting the requirements.


  • ASHRAE 90.1-2007 has some additional requirements compared with 2004. Read through the standard for a complete update. The following are some samples. 

    • All exterior walls must be installed with rigid insulation of the spans across all floors. This can be accomplished by placing the insulation outside the air barrier. 
    • All exterior doors must be tested for maximum air leakage rate. 
    • All spaces must have independent lighting controls. 
    • Occupancy sensors must be installed in some spaces.
    • The minimum efficiency level of specific mechanical equipment has been raised.  

  • The prerequisite’s energy-reduction target of 10% is not common practice and is considered beyond code compliance. 


  • ClerestoryIndirect sunlight delievered through clerestories like this helps reduce lighting loads as well as cooling loads. Photo – YRG Sustainability, Project – Cooper Union, New York A poorly designed envelope with a high-tech HVAC system is not, on the whole, efficient or cost-effective. Start with building orientation and passive design features first when looking for energy efficiency. Also look at envelope design, such as energy-efficient windows, walls and roof, before looking at HVAC and plug loads. HVAC may also be a good place to improve performance with more efficient equipment, but first reducing loads with smaller equipment can lead to even greater operational and upfront savings. A poorly designed envelope with a high-tech HVAC system is not, on the whole, efficient or cost-effective. 


  • Don’t plan on using onsite renewable energy generation (see EAc2) to make your building energy-efficient. It is almost always more cost-effective to make an efficient building, and then to add renewables like photovoltaics as the “icing” on the cake.


  • Some rules of thumb to reduce energy use are:

    • Program similar spaces together to reduce distribution losses 
    • Use a window-to-wall ratio below 40%, on average
    • Use a window-to-wall ratio below 20% on east and west sides, to reduce low-angle solar gain, and glare; 
    • Reduce direct solar gain with solar shades or building geometry and orientation
    • Distribute heating and cooling loads uniformly throughout all facades for a smaller system size. 
    • Design a tight and well-insulated building envelope to reduce the heating load and improve HVAC performance
    • Use right-sized and efficient heating and cooling systems
    • Consider onsite renewable energy generation.

  • Choosing your compliance path


  • Find the best credit compliance path based on your building type and energy-efficiency targets. Use the following considerations, noting that some projects are more suited to a prescriptive approach than others. 


  • Option 1: Whole Building Energy Simulation requires estimating the energy use of the whole building over a calendar year, using methodology established by ASHRAE 90.1-2007, Appendix G. Option 1 establishes a computer model of the building’s architectural design and all mechanical, electrical, domestic hot water, plug load, and other energy-consuming systems and devices. The model incorporates the occupancy load and a schedule representing projected usage in order to predict energy use. This compliance path does not prescribe any technology or strategy, but requires a minimum reduction in total energy cost of 10% (5% for an existing building), compared to a baseline building with the same form and design but using systems compliant with ASHRAE 90.1-2007. You can earn additional LEED points through EAc1 for cost reductions of 12% and greater (8% for existing buildings). 


  • Option 2: Prescriptive Compliance Path: ASHRAE Advanced Energy Design Guide refers to design guides published by ASHRAE for office, school, warehouse, and retail projects. These guides outline strategies to reduce energy use by 30% from ASHRAE 90.1-2001 levels, or an amount equivalent to a 10%–14% reduction from the ASHRAE 90.1-2007 standard. If you choose this compliance path, become familiar with the list of prescriptive requirements and commit to meeting them. (See the AEDG checklist in the Documentation Toolkit.) 


  • Option 3: Prescriptive Compliance Path: Advanced Buildings Core Performance Guide is another, more basic prescriptive path. It’s a good option if your project is smaller than 100,000 ft2, cannot pursue Option 2 (because there is not an ASHRAE guide for the building type), is not a healthcare facility, lab, or warehouse—or you would rather not commit to the energy modeling required for Option 1. Your project can be of any other building type (such as office or retail). To meet the prerequisite, you must comply with all requirements within Sections 1 and 2 of the guide. If you choose this path, become familiar with the list of activities and requirements and commit to meeting them. (See Resources for a link to the Core Performance Guide and the Documentation Toolkit for the checklist of prescriptive items.)


  • EAc1: Optimize Energy Performance uses the same structure of Options 1–3, so it makes sense to think about the credit and the prerequisite together when making your choice. In EAc1, Option 1 offers the potential for far more points than Options 2 and 3, so if you see your project as a likely candidate for earning those points, Option 1 may be best.


  • Hotels, multifamily residential, and unconventional commercial buildings may not be eligible for either Option 2 or Option 3, because the prescriptive guidance of these paths was not intended for them. Complex projects, unconventional building types, off-grid projects, or those with high energy-reduction goals are better off pursuing Option 1, which provides the opportunity to explore more flexible and innovative efficiency strategies and to trade off high-energy uses for lower ones. 


  • If your project combines new construction and existing building renovation then whatever portion contains more than 50% of the floor area would determine the energy thresholds.


  • Options 2 and 3 are suitable for small, conventional building types that may not have as much to gain from detailed energy modeling with Option 1. 


  • Meeting the prescriptive requirements of Options 2 and 3 is not common practice and requires a high degree of attention to detail by your project team. (See the Documentation Toolkit for the Core Performance Guide Checklist.) These paths are more straightforward than Option 1, but don’t think of them as easy. 


  • Options 2 and 3 require additional consultant time from architects and MEP engineers over typical design commitment, which means higher upfront costs. 


  • Option 1 references the mandatory requirements of ASHRAE 90.1-2007, which are more stringent than earlier LEED rating systems that referred to ASHRAE 90.1-2004.


  • Option 1 energy simulation provides monthly and annual operating energy use and cost breakdowns. You can complete multiple iterations, refining energy-efficiency strategies each time. Payback periods can be quickly computed for efficiency strategies using their additional first costs. A building’s life is assumed to be 60 years. A payback period of five years is considered a very good choice, and 10 years is typically considered reasonable. Consult the OPR for your owners’ goals while selecting your efficiency strategies. 


  • Option 1 energy simulation often requires hiring an energy modeling consultant, adding a cost (although this ranges, it is typically on the order of $0.10–$0.50/ft2 depending on the complexity). However, these fees produce high value in terms of design and decision-making assistance, and especially for complex or larger projects can be well worth the investment. 


  • All compliance path options may require both the architectural and engineering teams to take some time in addition to project management to review the prescriptive checklists, fill out the LEED Online credit form, and develop the compliance document. 


  • Option 1: Whole Building Energy Simulation


  • The architect, mechanical engineer, and lighting designer need to familiarize themselves and confirm compliance with the mandatory requirements of ASHRAE 90.1-2007, sections 5–9.


  • Use simple computer tools like SketchUp and Green Building Studio that are now available with energy analysis plug-ins to generate a first-order estimate of building energy use within a climate context and to identify a design direction. Note that you may need to refer to different software may not be the one used to develop complete the whole building energy simulations necessary for LEED certification. 


  • Energy modeling can inform your project team from the start of design. Early on, review site climate data—such as temperature, humidity and wind, available from most energy software—as a team. Evaluate the site context and the microclimate, noting the effects of neighboring buildings, bodies of water, and vegetation. Estimate the distribution of energy across major end uses (such as space heating and cooling, lighting, plug loads, hot water, and any additional energy uses), targeting high-energy-use areas to focus on during design.  


  • Energy use breakdown pie chartUse a preliminary energy use breakdown like this one to identify target areas for energy savings.Perform preliminary energy modeling in advance of the schematic design phase kick-off meeting or design charrette. The energy use breakdown can help identify targets for energy savings and point toward possible alternatives. 


  • For existing buildings, the baseline energy model can reflect the pre-renovation features like rather than a minimally ASHRAE-compliant building. This will help you achieve additional savings in comparison with the baseline.


  • Projects generating renewable energy onsite should use Option 1 to best demonstrate EAp2 compliance and maximize points under EAc1. Other options are possible but won’t provide as much benefit. Like any other project, model the baseline case as a system compliant with ASHRAE 90.1-2007, using grid-connected electricity, and the design case is an “as-designed” system also using grid-connected electricity. You then plug in 100% onsite renewable energy in the final energy-cost comparison table, as required by the performance rating method (PRM) or the modeling protocol of ASHRRAE 90.1 2007, Appendix G. (Refer to the sample PRM tables in the Documentation Toolkit for taking account of onsite renewable energy.


  • LEED divides energy-using systems into two categories: 

    • (i) Regulated loads. Most prominent systems—space heating, cooling, ventilation and pumps, lighting, and hot water—are regulated by ASHRAE and LEED so are termed “regulated” loads. Your energy model can provide insights into the energy use of all these systems. 
    • (ii) Non-regulated loads are those which are not directly associated with creating a comfortable environment, but with plug loads for machines. These include elevators, kitchen equipment, office equipment, televisions, and activity-oriented lighting, such as in hospitals. Though these are very large energy loads, they are not regulated by ASHRAE 90.1 or by LEED. Energy savings from specifying better equipment is not counted in energy models. It is typically expected that these non-regulated loads contribute to 25% of energy use.

  • The energy model itself will not account for any change in plug loads from the baseline case, even if your project is making a conscious effort to purchase Energy Star or other efficient equipment. Any improvement made in plug loads must be documented separately, using the exceptional calculation methodology (ECM), as described in ASHRAE 90.1-2007. These calculations determine the design case energy cost compared to the baseline case. They are included in the performance rating method (PRM) table or directly in the baseline and design case model. 


  • Besides energy modeling, you may need to use the exceptional calculation methodology (ECM) when any of the following situations occur: 

    • The energy software cannot carry out calculations for a specific systems like natural ventilation or unusual HVAC equipment.
    • Process loads are different in baseline and design cases and can influence total energy cost savings.
    • The proposed design can’t demonstrate savings with the modeling protocol and needs additional calculations. 

  • Some energy-modeling software tools have a daylight-modeling capability. Using the same model for both energy and IEQc8.1: Daylight and Views—Daylight can greatly reduce the cost of your modeling efforts.


  • Option 2: Prescriptive Compliance Path—ASHRAE Advanced Energy Design Guides


  • Provide a copy of the AEDG for office, retail, or warehouse, as applicable, to each team member as everyone, including the architect, mechanical and electrical engineers, lighting designer, and commissioning agents, are responsible for ensuring compliance. These are available to download free from the ASHRAE website. (See Resources.) 


  • Find your climate zone before attempting to meet any detailed prescriptive requirements. Climate zones vary by county, so be sure to select the right one. (See the Documentation Toolkit for a list of climate zones by county.)


  • Develop a checklist of all requirements, and assign responsible team members to accomplish them. Hold a meeting to walk the team through the AEDG checklist for your project’s climate zone. Clarify specific design goals and prescriptive requirements in the OPR for EAp1: Fundamental Commissioning.


  • Early access to the AEDG by each team member avoids last-minute changes that can have cascading, and costly, effects across many building systems. 


  • The AEDG prescriptive requirements include: 

    • a maximum allowable window-to-wall ratio;
    • continuous insulation on the outside of walls;
    • roofs and floor-slab minimum thermal performance;
    • minimum window and door thermal performance;
    • minimum boiler and chiller efficiencies;
    • and mandatory use economizers or heat recovery ventilation.

    If your project team is not comfortable following these guidelines, consider switching to Option 1, which gives you more flexibility. 


  • Although Option 2 is generally lower cost during the design phase than energy modeling, the compliance path is top heavy—it requires additional meeting time upfront for key design members. 


  • Option 3: Prescriptive—Advanced Buildings Core Performance Guide


  • Provide a copy of the New Buildings Institute Advanced Buildings: Core Performance Guide to each team member. The guide is available to download free from the NBI website. (See Resources.) 


  • The guide provides practical design assistance that can be used throughout the design process.


  • Walk your team through the project checklist to clarify design goals and prescriptive requirements. 


  • The guide provides an outline for approaching an energy-efficient design, in addition to a list of prescriptive measures. The first of its three sections emphasizes process and team interaction rather than specific building systems or features. Advise the owner to read through the guide in order to understand what is required of the architect and engineers. 


  • Section 1 in the guide focuses on best practices that benefit the project during the pre-design and schematic design stages, such as analyzing alternative designs and writing the owner’s project requirements (OPR). 


  • Section 2 of the Core Performance Guide describes architectural, lighting, and mechanical systems to be included. Section 3 is not required for EAp2 but includes additional opportunities for energy savings that can earn EAc1 points. 


  • The guide mandates that your team develop a minimum of three different design concepts to select from for best energy use.


  • Though they can be a little daunting at first glance, a majority of the guide’s requirements overlap with other LEED credits, such as EAp1: Fundamental Commissioning, IEQp1: Minimum Indoor Air Quality Performance, and IEQc6.1: Controllability of Systems—Lighting Controls


  • This compliance path is top-heavy due to upfront consultant time, but it provides adequate structure to ensure that your project is in compliance with the prerequisite requirements. For some projects it may be less expensive to pursue than Option 1. 

Schematic Design

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  • The owner should now have finalized the OPR with the support of the architect, as part of the commissioning credits EAp1 and EAc3. The goals identified here will help your team identify energy-reduction and occupant-comfort strategies.


  • Consider a broad range of energy-efficiency strategies and tools, including passive solar, daylighting, cooling-load reduction, and natural ventilation to reduce heating and cooling loads. 


  • Develop the basis of design (BOD) document in conjunction with your mechanical engineer and architect for EAp1: Fundamental Commissioning, noting key design parameters to help strategize design direction as outlined in the OPR. 


  • The OPR and BOD serve the larger purpose of documenting the owner’s vision and your team’s ideas to meet those goals. The BOD is intended to be a work-in-progress and should be updated at all key milestones in your project. Writing the document gives you an opportunity to capture the owner’s goals, whether just to meet the prerequisite or to achieve points under EAc1.


  • Confirm that your chosen compliance path is the most appropriate for your project, and make any changes now. Following a review with the design team and owner, ensure that everyone is on board with contracting an energy modeler for Option 1 or meeting all the prescriptive requirements under Options 2 or 3. 


  • Sometimes teams change from Option 1 to Options 2 or 3 very late in the design phase for various reasons including not realizing the cost of energy modeling. Making that change is risky, though: the prescriptive paths are all-or-nothing—you must comply with every item, without exception. Evaluate each requirement and consult with the contractor and estimator to ensure the inclusion of all activities within project management. 


  • To avoid costly, last-minute decisions, develop a comprehensive, component-based cost model as a decision matrix for your project. The model will help establish additional cost requirements for each energy conservation measure. It will also illustrate cost reductions from decreased equipment size, construction rendered unnecessary by energy conservation measures, and reduced architectural provisions for space and equipment access. (See the Documentation Toolkit for an example.)


  • Use envelope design and passive strategies to reduce the heating and cooling loads prior to detailed design of HVAC systems. Passive strategies can reduce heating and cooling loads, giving the engineer more options, including smaller or innovative systems.


  • Load reduction requires coordinated efforts by all design members including the architect, lighting designer, interior designer, information-technology manager, and owner. 

    • Architects can choose the optimum building orientation, select the appropriate envelope system and design it to be tight, and configure programming to utilize passive strategies as much as possible. 
    • Lighting designers help by harvesting daylight, making appropriate fixture selections, minimizing lighting layouts (fewer fixtures), providing maximum controls and daylight and occupancy sensors to reduce wasted light. 
    • Interior designers are critical for selecting reflective finishes to enhance daylighting and specifying Energy Star appliances. 
    • IT specialists are important, especially in buildings with data centers, for selection of computers and data-processing equipment that reduce the power load as well as cooling. 

  • Involving facilities staff in the design process can further inform key design decisions, helping ensure successful operation and low maintenance costs.


  • Encourage your design team to brainstorm design innovations and energy-reduction strategies. This provides a communication link among team members so they can make informed decisions. 


  • More energy-efficient HVAC equipment can cost more relative to conventional equipment. However, by reducing heating and cooling loads through good passive design, the mechanical engineer can often reduce the size and cost of the system. Reduced system size can save money through:

    • smaller chillers or boilers;
    • smaller fans, used less frequently;
    • smaller pumps and auxiliary systems;
    • smaller ducts;
    • and less square footage devoted to mechanical systems.

  • Review case studies of similar energy-efficient buildings in the same climate to provide helpful hints for selecting energy-efficiency measures. For example, a building in a heating-dominated climate can often benefit from natural ventilation and free cooling during shoulder seasons. (See Resources for leading industry journals showcasing success stories around the country and internationally.)


  • The relationship between first costs and operating costs can be complex. For example, more efficient windows will be more expensive, but could reduce the size and cost of mechanical equipment. A more efficient HVAC system may be more expensive, but will reduce operating costs. Play around with variables and different strategies to get the right fit for the building and the owner’s goals as stated in the OPR.


  • Option 1: Whole Building Energy Simulation


  • Review and confirm compliance with the mandatory requirements of all the relevant sections of ASHRAE 90.1-2007


  • Trust your project’s energy modeling task to a mechanical firm with a proven track record in using models as design tools, and experience with your building type.


  • Contract an energy modeling team for the project. These services may be provided by the mechanical engineering firm on the design team or by an outside consultant. Software used for detailed energy use analysis and submitted for final LEED certification must be accepted by the regulatory authority with jurisdiction, and must comply with paragraph G2.2 of ASHRAE Standard 90.1-2007. Refer to Resources for a list of Department of Energy approved energy-analysis software that may be used for LEED projects.


  • Design team members, including the architect and mechanical engineer at a minimum, need to work together to identify a percentage improvement goal for project energy use over the ASHRAE 90.1-2007-compliant baseline model. The percentage should be at least 10% to meet the prerequisite. 


  • Plan on initiating energy modeling during the design process, and use it to inform your design—preferably executing several iterations of the design as you improve the modeled energy performance. 


  • Ask the modeling consultant to develop an annual energy-use breakdown—in order to pick the “fattest” targets for energy reduction. A typical energy-use breakdown required for LEED submission and ASHRAE protocol includes: 

    • lighting;
    • space heating;
    • space cooling;
    • domestic hot water;
    • additional installed heat recovery, refrigeration, or heat-rejection systems;
    • ventilation fans and auxiliary pumps;
    • and equipment and plug loads. 

  • Identify critical areas in which to reduce loads. For example, in a data center, the plug loads are the largest energy load. Small changes in lighting density might bring down the energy use but represent only a small fraction of annual energy use. 


  • Don't forget that LEED (following ASHRAE) uses energy cost and not straight energy when it compares your design to a base case. That's important because you might choose to use a system that burns natural gas instead of electricity and come out with a lower cost, even though the on-site energy usage in kBtus or kWhs is higher. Generally you have to specify the same fuel in your design case and in the base case, however, so you can't simply switch fuels to show a cost savings


  • Explore and analyze design alternatives for energy use analyses to compare the cost-effectiveness of your design choices. For example, do you get better overall performance from a better window or from adding a PV panel? Will demand-control ventilation outperform increased ceiling insulation?


  • Simple, comparative energy analyses of conceptual design forms are useful ways to utilize an energy model at this stage. Sample scenarios include varying the area of east-facing windows and looking at 35% versus 55% glazing. Each scenario can be ranked by absolute energy use to make informed decisions during the design stage. 


  • If your project is using BIM software, the model can be plugged into the energy analysis software to provide quick, real-time results and support better decisions. 


  • Model development should be carried out following the PRM from ASHRAE 90.1-2007, Appendix G, and the LEED 2009 Design and Construction Reference Guide, Table in EAc1. In case of a conflict between ASHRAE and LEED guidelines, follow LEED.


  • Projects using district energy systems have special requirements. For EAp2, the proposed building must achieve the 10% energy savings without counting the effects of the district generation system. To earn points in EAc1 you can take advantage of the district system’s efficiency, but you have to run the energy model again to claim those benefits (see EAc1 for details). 


  • While you could run the required energy model at the end of the design development phase, simply to demonstrate your prerequisite compliance, you don’t get the most value that way in terms of effort and expense. Instead, do it early in the design phase, and run several versions as you optimize your design. Running the model also gives you an opportunity to make improvements if your project finds itself below the required 10% savings threshold.


  • The baseline model is the designed building with mechanical systems specified in ASHRAE 90.1-2007, Appendix G, for the specific building type, with a window-to-wall ratio at a maximum of 40%, and minimally code-compliant specifications for the envelope, lighting, and mechanical components. It can be developed as soon as preliminary drawings are completed. The baseline is compared to the design case to provide a percentage of reduction in annual energy use. To avoid any bias from orientation, you need to run the baseline model in each of the four primary directions, and the average serves as your final baseline figure. 


  • The design-case is modeled using the schematic design, orientation, and proposed window-to-wall ratio—¬the model will return design-case annual energy costs. Earn points by demonstrating percentage reductions in annual energy costs from the design to the baseline case. EAp2 is achieved if the design case is 10% lower than the baseline in new construction (or 5% less in existing building renovations). 


  • Provide as much project and design detail to the modeler as possible. A checklist is typically developed by the energy modeler, listing all the construction details of the walls, roof, slabs, windows, mechanical systems, equipment efficiencies, occupancy load, and schedule of operations. Any additional relevant information or design changes should be brought to the modeler’s attention as soon as possible. The more realistic the energy model is, the more accurate the energy use figure, leading to better help with your design.


  • Invite energy modelers to project meetings. An experienced modeler can often assist in decision-making during design meetings, even without running complete models each time. 


  • All known plug loads must be included in the model. The baseline and design-case models assume identical plug loads. If your project is deliberately attempting to reduce plug loads, demonstrate this by following the exceptional calculation method (ECM), as described in ASHRAE 90.1-2007, G2.5. Incorporate these results in the model to determine energy savings. 


  • For items outside the owner’s control—like lighting layout, fans and pumps—the parameters for the design and baseline models must be identical.


  • It can take anywhere from a few days to a few weeks to generate meaningful energy modeling results. Schedule the due dates for modeling results so that they can inform your design process.


  • Review the rate structure from your electrical utility. The format can inform your team of the measures likely to be most effective in reducing energy costs, especially as they vary over season, peak load, and additional charges beyond minimum energy use.


  • Performing a cost-benefit analysis in conjunction with energy modeling can determine payback times for all the energy strategies, helping the iterative design process.


  • Using energy modeling only to check compliance after the design stage wastes much of the value of the service, and thus your investment.


  • Option 2: Prescriptive—ASHRAE Advanced Energy Design Guides 


  • The architect and mechanical engineer should carefully read the applicable ASHRAE Advanced Energy Design Guide for office, warehouse, or retail projects, as applicable. 


  • Keep the owner abreast of the design decisions dictated by the standard. Fill in the team-developed checklist, within the climate zone table’s prescribed requirements, with appropriate envelope improvements, system efficiencies, and a configuration that meets the standard requirements. 


  • As a prescriptive path, this option relies heavily on following the requirement checklist, which is used throughout the design process to track progress. To assist design development, provide all critical team members—not limited to the architect, mechanical and electrical engineers, and lighting designer—with a checklist highlighting their appointed tasks.


  • The architect, mechanical engineer, and lighting designer need to discuss each requirement and its design ramifications. Hold these meetings every six to eight weeks to discuss progress and make sure all requirements are being met.


  • Confirm that your project team is comfortable with following all the prescribed requirements. If not, switch to Option 1: Whole Building Energy Simulation. 


  • The LEED Online credit form does not specify how to document each prescriptive requirement because they are so different for each project; it only requires a signed confirmation by the MEP for meeting AEDG requirements. You still have to provide documentation. Submit your checklist of requirements, and supporting information for each item, through LEED Online to make your case. If your project fails to meet even one requirement, it will fail to earn the prerequisite, thus jeopardizing LEED certification.  


  • Although energy modeling consultant costs are avoided by this option, additional staff time will be required to document and track compliance status, as compared with conventional projects.


  • Energy efficiency measures prescribed by the guide can be perceived as additional costs in comparison with conventional projects. However, they are easy to implement and are cost-effective pn the whole.


  • Option 3: Prescriptive Compliance Path—Advanced Buildings Core Performance Guide 


  • Become familiar with the Core Performance Guide early in the design phase to know the multiple requirements and all requisite documents.


  • Note that the guide demands additional time, attention, and integrated process from the design team as compared to conventional projects. It’s not just a list of prescriptive requirements, but a prescribed process for achieving energy efficiency goals. LEED Online documentation requires proof of all steps outlined in Sections 1 and 2, including three conceptual design options and meeting minutes. The project manager, architect, and mechanical engineer should read the complete Core Performance Guide carefully to know beforehand the prescriptive requirements in Sections 1 and 2. 


  • The project manager must take responsibility for ensuring that the requirement checklist is on track.


  • For Section 3, the design team needs to identify three or more of the listed strategies as possible targets for the project. 


  • Create a checklist of requirements and assign a responsible party to each item. 


  • The Core Performance Guide requires an integrated design contributed by the architect, mechanical and electrical engineers, and lighting designer. The project manager must take responsibility for shepherding and documenting the collaborative process to demonstrate compliance. 


  • A long documentation list can be overwhelming for your team, so create a detailed checklist with tasks delegated to individual team members, allowing each member to focus on assigned tasks. The checklist can function as a status tracking document and, finally, the deliverable for LEED Online.

Design Development

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  • The architect and engineer, and other project team members, continue to develop a high-performance building envelope with efficient mechanical and lighting systems. 


  • Constant communication and feedback among project team members, owner, and if possible, operational staff, during design development can minimize construction as well as operational costs and keep your project on schedule. 


  • If you change or go through value-engineering on any specifications, such as the solar-heat gain coefficient of glazing, for example, be aware of impacts on mechanical system sizing. Making changes like this might not pay off as much as it first appears.


  • Consider using building information modeling (BIM) tools to keep design decisions up to date and well documented for all team members.


  • Schedule delays can be avoided if all team members share their ideas and update documents during the design development process. 


  • Option 1: Whole Building Energy Simulation


  • The modeler completes the energy analysis of the selected design and system and offers alternative scenarios for discussion. The modeler presents the energy cost reduction results to the team, identifying the LEED threshold achieved.


  • It’s helpful for the energy modeling report to include a simple payback analysis to assist the owner in making an informed decision on the operational savings of recommended features. 


  • The architect and HVAC engineer should agree on the design, working with the cost estimator and owner.


  • Demonstrating reductions in non-regulated loads requires a rigorous definition of the baseline case. The loads must be totally equivalent, in terms of functionality, to the proposed design case. For example, reducing the number of computers in the building does not qualify as a legitimate reduction in non-regulated loads. However, the substitution of laptops for desktop computers, and utilization of flat-screen displays instead of CRTs for the same number of computers, may qualify as a reduction.


  • Residential and hospitality projects that use low-flow showers, lavatories, and kitchen sinks (contributing to WEp1) benefit from lower energy use due to reduced overall demand for hot water. However, for energy-savings calculations, these are considered process loads that must be modeled as identical in baseline and design cases, or you have the choice of demonstrating the savings with ECM for process loads. 


  • Perform daylight calculations in conjunction with energy modeling to balance the potentially competing goals of more daylight versus higher solar-heat gain resulting in high cooling loads. 


  • If your project is pursuing renewable energy, the energy generated is accounted for by using the PRM. These results provide information about whether the energy is contributing to EAc2: Onsite Renewable Energy. 


  • A cost-benefit analysis can help the owner understand the return on investment of big-ticket, energy-conserving equipment that lowers operating energy bills with a quick payback. 


  • Complete at least half of the energy modeling effort by the end of the design development stage. Help the design team to finalize strategy through intensive, early efforts in energy modeling. Once the team has a design direction, the modeler can develop a second model during the construction documents phase for final confirmation. 


  • If pursuing ECM for non-regulated loads, calculate energy saving for each measure separately if you are, for example, installing an energy-efficient elevator instead of a typical one so that the reduction would contribute to total building energy savings. Calculate the anticipated energy use of the typical elevator in kBTUs or kWh. Using the same occupancy load, calculate the energy use of the efficient elevator. Incorporate the savings into design case energy use within the PRM. Refer to the ECM strategy for detailed calculation guidelines. 


  • Option 2: Prescriptive Compliance Path—ASHRAE Advanced Energy Design Guides 


  • Ensure that all prescriptive requirements are incorporated into the design by the end of the design development stage.


  • Revisit the Advanced Energy Design Guides (AEDG) checklist to ensure that the design meets the prescriptive requirements.


  • Option 3: Prescriptive Compliance Path—Advanced Buildings Core Performance Guide


  • The mechanical engineer, lighting consultant, and architect revisit the checklist for an update on the requirements and how they are being integrated into the design. All prescriptive requirements should be specifically incorporated into the design by the end of the design development phase. 


  • The mechanical engineer and architect track the status of each requirement.


  • While the LEED Online credit form does not require detailed documentation for each Core Performance Guide requirement, it is important that each item be documented as required and reviewed by the rest of the team to confirm compliance, especially as further documentation may be requested by during review. Your design team should work with the owner to identify cost-effective strategies from Section 3 that can be pursued for the project. 

Construction Documents

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  • Construction documents clearly detail the architectural and mechanical systems that address energy-efficiency strategies.  


  • Confirm that specifications and the bid package integrate all equipment and activities associated with the project. 


  • If the project goes through value engineering, refer to the OPR and BOD to ensure that no key comfort, health, productivity, daylight, or life-cycle cost concerns are sacrificed.


  • During the budget estimating phase, the project team may decide to remove some energy-saving strategies that have been identified as high-cost items during the value-engineering process. However, it is very important to help the project team understand that these so-called add-ons are actually integral to the building’s market value and the owner’s goals. 


  • Removing an atrium, for example, due to high cost may provide additional saleable floor area, but may also reduce daylight penetration while increasing the lighting and conditioning loads.  


  • Option 1: Whole Building Energy Simulation


  • Although this prerequisite is a design-phase submittal, it may make sense to submit it, along with EAc1, after construction. Your project could undergo changes during construction that might compel a new run of the energy model to obtain the latest energy-saving information. Waiting until the completion of construction ensures that the actual designed project is reflected in your energy model.


  • Create a final energy model based completely on construction document drawings—to confirm actual energy savings as compared to ASHRAE 90.1-2007 requirements. An energy model based on the construction documents phase will provide realistic energy-cost savings and corresponding LEED points likely to be earned. 


  • Make sure the results fit the LEED Online credit form requirements. For example, the unmet load hours have to be less than 300 and process loads will raise a red flag if they’re not approximately 25%. If any of the results are off mark, take time to redo the model. Time spent in design saves more later on in the LEED review process. 


  • Option 2: Prescriptive Compliance Path—ASHRAE Advanced Energy Design Guides


  • Finalize all design decisions and confirm that you’ve met all of the prescriptive requirements. Your team must document the checklist with relevant project drawings, including wall sections, specifications, and the MEP drawing layout.


  • Value engineering and other factors can result in design changes that eliminate certain energy features relevant to the prerequisite. As this compliance path is prescriptive, your project cannot afford to drop even one prescribed item.


  • Option 3: Prescriptive Compliance Path—Advanced Buildings Core Performance Guide


  • Finalize all design decisions and confirm that you’ve met all of the prescriptive requirements. Your team must document the checklist with relevant project drawings, including wall sections, specifications, and the MEP drawing layout.


  • Value engineering and other factors can result in design changes that eliminate certain energy features relevant to the credit. As this compliance path is prescriptive, your project cannot afford to drop even one listed item. Although perceived as high-cost, prescriptive requirements lower energy costs during operation and provide a simple payback structure. 

Construction

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  • The architect and mechanical engineer review the shop drawings to confirm the installation of the selected systems. 


  • The commissioning agent and the contractor conduct functional testing of all mechanical equipment in accordance with EAp1: Fundamental Commissioning and EAc3: Enhanced Commissioning. 


  • Find your Energy Star rating with EPA’s Target Finder tool if your building type is in the database. Input your project location, size, and number of occupants, computers, and kitchen appliances. The target may be a percentage energy-use reduction compared to a code-compliant building, or “anticipated energy use” data from energy model results. Add information about your fuel use and rate, then click to “View Results.” Your Target Finder score should be documented at LEED Online.


  • Plan for frequent site visits by the mechanical designer and architect during construction and installation to make sure construction meets the design intent and specifications. 


  • Emphasize team interaction and construction involvement when defining the project scope with key design team members. Contractor and designer meetings can help ensure correct construction practices and avoid high change-order costs for the owner. 


  • Subcontractors may attempt to add a premium during the bidding process for any unusual or unknown materials or practices, so inform your construction bidders of any atypical design systems at the pre-bid meeting.


  • Option 1: Whole Building Energy Simulation


  • The energy modeler ensures that any final design changes have been incorporated into the updated model.


  • Upon finalizing of the design, the responsible party or energy modeler completes the LEED Online submittal with building design inputs and a PRM result energy summary. 


  • Although EAp2 is a design phase submittals, it may make sense to submit it (along with EAc1) after construction. Your project could undergo changes during construction that might require a new run of the energy model. Waiting until the completion of construction ensures that your actual designed project is reflected. On the other hand, it gives you less opportunity to respond to questions that might come up during a LEED review. 


  • Include supporting documents like equipment cut sheets, specifications and equipment schedules to demonstrate all energy efficiency measures claimed in the building. 


  • It common for the LEED reviewers to make requests for more information. Go along with the process—it doesn’t mean that you’ve lost the credit. Provide as much information for LEED Online submittal as requested and possible. 


  • Option 2: Prescriptive Compliance Path—ASHRAE Advanced Energy Design Guides (AEDG)


  • The design team completes the LEED Online documentation, signing off on compliance with the applicable AEDG, and writing the narrative report on the design approach and key highlights.


  • During LEED submission, the project team needs to make an extra effort to support the prerequisite with the completed checklist and the required documents. Although the LEED rating system does not list detailed documentation, it is best practice to send in supporting documents for the prescriptive requirements from the AEDG. The supporting documents should include relevant narratives, wall sections, mechanical drawings, and calculations. 


  • Although the LEED Online sign-off does not include a checklist of AEDG requirements, it assumes that the team member is confirming compliance with all detailed requirements of the guide. 


  • Option 3: Prescriptive Compliance Path—Advanced Building Core Performance Guide


  • The design team completes the LEED Online credit form, signing off on compliance with the Core Performance Guide, and writing the narrative report on the design approach and key highlights.


  • During LEED submission, your project team needs to make an extra effort to support the prerequisite with the completed checklist and the required documents. Although not every requirement may be mentioned in the LEED documentation, the supporting documents need to cover all requirements with narratives, wall sections, mechanical drawings, and calculations. 


  • Many of this option’s compliance documents are common to other LEED credits or design documents, thus reducing duplicated efforts. 

Operations & Maintenance

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  • Develop an operations manual with input from the design team in collaboration with facility management and commissioning agent if pursuing EAc3: Enhanced Commissioning. 


  • The benefit of designing for energy efficiency is realized only during operations and maintenance. Record energy use to confirm that your project is saving energy as anticipated. If you are not pursuing EAc5: Measurement and Verification, you can implement tracking procedures such as reviewing monthly energy bills or on-the-spot metering.


  • Some energy efficiency features may require special training for operations and maintenance personnel. For example, cogeneration and building automation systems require commissioning and operator training. Consider employing a trained professional to aid in creating operation manuals for specialty items. 


  • Energy-efficiency measures with a higher first cost often provide large savings in energy use and operational energy bills. These credit requirements are directly tied to the benefits of efficient, low-cost operations.

  • USGBC

    Excerpted from LEED 2009 for New Construction and Major Renovations

    EA Prerequisite 2: Minimum energy performance

    Required

    Intent

    To establish the minimum level of energy efficiency for the proposed building and systems to reduce environmental and economic impacts associated with excessive energy use.

    Requirements

    Option 1. Whole building energy simulation

    Demonstrate a 10% improvement in the proposed building performance rating for new buildings, or a 5% improvement in the proposed building performance rating for major renovations to existing buildings, compared with the baseline building performanceBaseline building performance is the annual energy cost for a building design, used as a baseline for comparison with above-standard design. rating.

    Calculate the baseline building performance rating according to the building performance rating method in Appendix G of ANSI/ASHRAE/IESNA Standard 90.1-2007 (with errata but without addenda1) using a computer simulation model for the whole building project. Projects outside the U.S. may use a USGBC approved equivalent standard2.

    Appendix G of Standard 90.1-2007 requires that the energy analysis done for the building performance rating method include all energy costs associated with the building project. To achieve points using this credit, the proposed design must meet the following criteria:

    • Comply with the mandatory provisions (Sections 5.4, 6.4, 7.4, 8.4, 9.4 and 10.4) in Standard 90.1-2007 (with errata but without addenda1) or USGBC approved equivalent.
    • Inclusion of all the energy costs within and associated with the building project.
    • Compare against a baseline building that complies with Appendix G of Standard 90.1-2007 (with errata but without addenda1) or USGBC approved equivalent. The default process energy cost is 25% of the total energy cost for the baseline building. If the building’s process energy cost is less than 25% of the baseline building energy cost, the LEED submittal must include documentation substantiating that process energy inputs are appropriate.

    For the purpose of this analysis, process energy is considered to include, but is not limited to, office and general miscellaneous equipment, computers, elevators and escalators,kitchen cooking and refrigeration, laundry washing and drying, lighting exempt from the lighting power allowance (e.g., lighting integral to medical equipment) and other (e.g., waterfall pumps).

    Regulated (non-process) energy includes lighting (for the interior, parking garage, surface parking, façade, or building grounds, etc. except as noted above), heating, ventilation and air conditioning (HVAC) (for space heating, space cooling, fans, pumps, toilet exhaust, parking garage ventilation, kitchen hood exhaust, etc.), and service water heating for domestic or space heating purposes.

    Process loads must be identical for both the baseline building performance rating and the proposed building performance rating. However, project teams may follow the exceptional calculation method (ANSI/ASHRAE/IESNA Standard 90.1-2007 G2.5) or USGBC approved equivalent to document measures that reduce process loads. Documentation of process load energy savings must include a list of the assumptions made for both the base and the proposed design, and theoretical or empirical information supporting these assumptions.

    Projects in California may use Title 24-2005, Part 6 in place of ANSI/ASHRAE/IESNA Standard 90.1-2007 for Option 1.

    OR

    Option 2. Prescriptive compliance path: ASHRAE Advanced Energy Design Guide

    Comply with the prescriptive measures of the ASHRAE Advanced Energy Design Guide appropriate to the project scope, outlined below. Project teams must comply with all applicable criteria as established in the Advanced Energy Design Guide for the climate zoneOne of five climatically distinct areas, defined by long-term weather conditions which affect the heating and cooling loads in buildings. The zones were determined according to the 45-year average (1931-1975) of the annual heating and cooling degree-days (base 65 degrees Fahrenheit). An individual building was assigned to a climate zone according to the 45-year average annual degree-days for its National Oceanic and Atmospheric Administration (NOAA) Division. in which the building is located. Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone.

    Path 1. ASHRAE Advanced Energy Design Guide for Small Office Buildings 2004

    The building must meet the following requirements:

    • Less than 20,000 square feet (1,800 square meters).
    • Office occupancy.
    Path 2. ASHRAE Advanced Energy Design Guide for Small Retail Buildings 2006

    The building must meet the following requirements:

    • Less than 20,000 square feet (1,800 square meters).
    • Retail occupancy.
    Path 3. ASHRAE Advanced Energy Design Guide for Small Warehouses and Self Storage Buildings 2008

    The building must meet the following requirements:

    • Less than 50,000 square feet (4,600 square meters).
    • Warehouse or self-storage occupancy.

    OR

    Option 3. Prescriptive compliance path: Advanced Buildings™ Core Performance™ Guide

    Comply with the prescriptive measures identified in the Advanced Buildings™ Core Performance™ Guide developed by the New Buildings Institute. The building must meet the following requirements:

    • Less than 100,000 square feet (9,300 square meters).
    • Comply with Section 1: Design Process Strategies, and Section 2: Core Performance Requirements.
    • Health care, warehouse and laboratory projects are ineligible for this path.

    Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone.

    1Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.

    2 Projects outside the U.S. may use an alternative standard to ANSI/ASHRAE/IESNA Standard 90.1-2007 if it is approved by USGBC as an equivalent standard using the process identified in the LEED 2009 Green Building Design and Construction Global ACP Reference Guide Supplement.

    Potential Technologies & Strategies

    Design the building envelope and systems to meet baseline requirements. Use a computer simulation model to assess the energy performance and identify the most cost-effective energy efficiency measures. Quantify energy performance compared with a baseline building.

    If local code has demonstrated quantitative and textual equivalence following, at a minimum, the U.S. Department of Energy (DOE) standard process for commercial energy code determination, then the results of that analysis may be used to correlate local code performance with ANSI/ASHRAE/IESNA Standard 90.1-2007. Details on the DOE process for commercial energy code determination can be found at http://www.energycodes.gov/implement/
    determinations_com.stm.

    FOOTNOTES

    1 Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.

    2 Projects outside the U.S. may use an alternative standard to ANSI/ASHRAE/IESNA Standard 90.1‐2007 if it is approved by USGBC as an equivalent standard using the process located at www.usgbc.org/leedisglobal

Organizations

Database of State Incentives for Renewables and Efficiency (DSIRE)

This database shows state-by-state incentives for energy efficiency, renewable energy, and other green building measures. Included in this database are incentives on demand control ventilation, ERVs, and HRVs.


New York State Energy Research and Development Authority (NYSERDA)

Useful web resource with information on local/regional incentives for energy-efficiency programs.


American Council for an Energy-Efficient Economy

ACEEE is a nonprofit organization dedicated to advancing energy efficiency through technical and policy assessments; advising policymakers and program managers; collaborating with businesses, public interest groups, and other organizations; and providing education and outreach through conferences, workshops, and publications. 


New Buildings Institute

The New Buildings Institute is a nonprofit, public-benefits corporation dedicated to making buildings better for people and the environment. Its mission is to promote energy efficiency in buildings through technology research, guidelines, and codes.


U.S. Department of Energy, Building Energy Codes Program

The Building Energy Codes program provides comprehensive resources for states and code users, including news, compliance software, code comparisons, and the Status of State Energy Codes database. The database includes state energy contacts, code status, code history, DOE grants awarded, and construction data. The program is also updating the COMcheck-EZ compliance tool to include ANSI/ASHRAE/IESNA 90.1–2007. This compliance tool includes the prescriptive path and trade-off compliance methods. The software generates appropriate compliance forms as well. 


Rensselaer Polytechnic Institute: Daylighting Resources

Research center at RPI provides access to a wide range of  daylighting resources, case studies, design tools, reports, publications and more.


IBPSA

International association of energy modelers with various national and local chapters. 


Architecture 2030

Non-profit organization aiming at design community to increase collaboration for designing energy efficient buildings.


Low Impact Hydropower Institute

The Low Impact Hydropower Institute is a non-profit organization and certification body that establishes criteria against which to judge the environmental impacts of hydropower projects in the United States.


U.S. Department of Energy Building Technologies Program

The Building Technologies Program (BTP) provides resources for commercial and residential building components, energy modeling tools, building energy codes, and appliance standards including the Buildings Energy Data Book, High Performance Buildings Database and Software Tools Directory.

Web Tools

Energy Analysis Tools

This website discusses the step-by-step process for energy modeling.


Advanced Buildings Technologies and Practices

This online resource, supported by Natural Resources Canada, presents energy-efficient technologies, strategies for commercial buildings, and pertinent case studies.


U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy

This website is a comprehensive resource for U.S. Department of Energy information on energy efficiency and renewable energy and provides access to energy links and downloadable documents. 


U.S. EPA, Combined Heat and Power Partnership

Information on cogenerationThe simultaneous production of electric and thermal energy in on-site, distributed energy systems; typically, waste heat from the electricity generation process is recovered and used to heat, cool, or dehumidify building space. Neither generation of electricity without use of the byproduct heat, nor waste-heat recovery from processes other than electricity generation is included in the definition of cogeneration., also called combined heat and power, is available from EPA through the CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. Partnership. The CHP Partnership is a voluntary program seeking to reduce the environmental impact of power generation by promoting the use of CHP. The Partnership works closely with energy users, the CHP industry, state and local governments, and other clean energy stakeholders to facilitate the development of new projects and to promote their environmental and economic benefits. 


Advanced Energy Design Guides

Free download of AHSRAE energy savings guide, use for Option 2.


Lawrence Berkeley Lab: Building Technologies Department

Research warehouse for strategies and case studies of energy efficiency in buildings.


Efficient Windows Collaborative

An online window selection tool with performance characteristics.


Whole Building Design Guide (WBDG)

This website lays out design process for developing an energy efficient building.


AIA Sustainability 2030 Toolkit

This website discusses ways to improve design for lower energy demand as they relate to the AIA 2030 challenge.


Windows for High-Performance Commercial Buildings

This website includes discussion of design issues, materials and assemblies, window design decisions and case studies. 


California Integrated Waste Management Board: Environmental and Economic Assessment Tools

This site lists multiple web-based and downloadable tools that can be used for energy analyses.


DEER: Database for Energy Efficient Resource

This database is maintainted by the California Energy Commission and lists resources related to energy use and efficiency. 


Energy Design Resources - CA

Energy design tools are available to be used for free online or available to download.


Building Materials Property Table

This website lists performance characteristics for various envelope materials. 


One Building

This is an online forum of discussion for energy efficiency, computer model software users.


EPA’s Target Finder

Target Finder is a goal-setting tool that informs your design team about their project’s energy performance as compared to a national database of projects compiled by the EPA.


Building Energy Software Tools Directory

This directory provides information on 406 building software tools for evaluating energy efficiency, renewable energy, and sustainability in buildings.


EnergyPlus Format Weather Data Resources

Weather data for more than 2100 locations are available in EnergyPlus weather format.


DOE-2 Format Weather Data Resources

Weather data for U.S. and Non-U.S. locations in BIN format.


BEMbook – Building Energy Modeling Book

A web-based, free content project by IBPSA-USA to develop an online compendium of the domain of Building Energy Modeling (BEM). The intention is to delineate a cohesive body of knowledge for building energy modeling.

Technical Guides

Advanced Buildings Core Performance Guide

A guide for achieving energy efficiency in new commercial buildings, referenced in the LEED energy credits.


ENERGY STAR Building Upgrade Manual

This manual is a strategic guide for planning and implementing energy-saving building upgrades. It provides general methods for reviewing and adjusting system control settings, plus procedures for testing and correcting calibration and operation of system components such as sensors, actuators, and controlled devices.


Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 – Design & Construction

This document is USGBC’s second (v2.0) major release of guidance for district or campus thermal energy in LEED, and is a unified set of guidance comprising the following an update to the original Version 1.0 guidance released May 2008 for LEED v2.x and the initial release of formal guidance for LEED v2009.


COMNET Commercial Buildings Energy Modeling Guidelines and Procedures

This manual offers guidance to building energy modelers, ensuring technically rigorous and credible assessment of energy performance of commercial and multifamily residential buildings. It provides a streamlined process that can be used with various existing modeling software and systems, across a range of programs.


2009 ASHRAE Handbook of Fundamentals, Chapter 19

Chapter 19 is titled, “Energy Estimating and Modeling Methods”. The chapter discusses methods for estimating energy use for two purposes: modeling for building and HVAC system design and associated design optimization (forward modeling), and modeling energy use of existing buildings for establishing baselines and calculating retrofit savings (data-driven modeling).


Treatment of Distric or Campus Thermal Energy in LEED v2 and LEED 2009 (Updated August 13, 2010)

Required reference document for DES systems in LEED energy credits.

Publications

ANSI/ASHRAE/IESNA Standard 90.1–2007 User’s Manual (ASHRAE).

ASHRAE writes standards for the purpose of establishing consensus for: 1) methods of test for use in commerce and 2) performance criteria for use as facilitators with which to guide the industry.


Energy Information Administration

Energy statistics from the U.S. government.


New Buildings Institute— Advanced Lighting Guidelines: 2003 Edition

This guide includes instructional graphics and superior lighting design solutions for varying types of buildings and spaces, from private offices to big box retail stores.


Building Energy Performance News

This website offers information on energy efficiency in buildings, highlighting success stories, breakthrough technology, and policy updates.


GreenSource magazine

Bimonthly publication on case studies and new technologies for energy efficiency in commercial buildings. 


AIA Local Leaders in Sustainability: Green Incentives

AIA publication highlighting local and state green building incentives.


Federal Research and Devlopment Agenda for Net-Zero Energy, High-Performance Green Buildings

2008 guidelines and performance goals from the National Science and Technology Council.


Energy Design Resources (EDR) Simulation Guidebooks

Information about energy-efficient building practices available in EDR's Design Briefs, Design Guidelines, Case Studies, and Technology Overviews.

Software Tools

Building Energy Software Tools Directory

DOE tools for whole building analyses, including energy simulation, load calculation, renewable energy, retrofit analysis and green buildings tools.


Building and Fire Research Laboratory

This is a computer program that predicts the one-dimensional transfer of heat and moisture.


DesignBuilder and EnergyPlus

DesignBuilder is a Graphical User Interface to EnergyPlus. DesignBuilder is a complete 3-D graphical design modeling and energy use simulation program providing information on building energy consumption, CO2Carbon dioxide emissions, occupant comfort, daylighting effects, ASHRAE 90.1 and LEED compliance, and more.


Integrated Environmental Solutions – Virtual Environment Pro / Apache

IES VE Pro is an integrated computing environment encompassing a wide range of tasks in building design including model building, energy/carbon, solar, light, HVAC, climate, airflow, value/cost and egress.

Advanced Energy Design Guide Checklist

Option 2: Prescriptive Compliance Path

Use this checklist of prescriptive requirements (with sample filled out) to have an at-a-glance picture of AEDG requirements for Option 2, and how your project is meeting them.

Advanced Buildings Core Performance Guide (CPG) Checklist

Option 3

This spreadsheet lists all the requirements for meeting EAp2 – Option 3 and and EAc1 – Option 3. You can review the requirements, assign responsible parties and track status of each requirement through design and construction.

Energy Simulation Narrative

Option 1

Sometimes the energy simulation software being used to demonstrate compliance with Option 1 doesn't allow you to simulate key aspects of the design. In this situation you'll need to write a short sample narrative, as in these examples, describing the situation and how it was handled.

Equipment and Product Cut Sheets

All Options

In your supporting documentation, include spec sheets of equipment described in the Option 1 energy model or Options 2–3 prescriptive paths.

PRM Table

Option 1

This is a sample building energy performance and cost summary using the Performance Rating Method (PRM). Electricity and natural gas use should be broken down by end uses including space heating, space cooling, lights, task lights, ventilation fans, pumps, and domestic hot water, at the least.

Tariff Charges

Option 1

Option 1 calculates savings in annual energy cost, but utility prices may vary over the course of a year. This sample demonstrates how to document varying electricity tariffs.

Modeled Energy Reductions

Option 1

This graph, for an office building design, shows how five overall strategies were implemented to realize energy savings of 30% below an ASHRAE baseline. (From modeling conducted by Synergy Engineering, PLLC.)

U.S. Climate Zones

All Options

The climate zones shown on this Department of Energy map are relevant to all options for this credit.

Appendix G Fan Power Calculator

Option 1

This spreadsheet, provided here by 7group, can be used to calculate the fan volume and fan power for Appendix G models submitted for EAp2/EAc1.  Tabs are included to cover both ASHRAE 90.1-2004 and 90.1-2007 Appendix G methodologies.

LEED Online Forms: NC-2009 EA

The following links take you to the public, informational versions of the dynamic LEED Online forms for each NC-2009 EA credit. You'll need to fill out the live versions of these forms on LEED Online for each credit you hope to earn.

Version 4 forms (newest):

Version 3 forms:

These links are posted by LEEDuser with USGBC's permission. USGBC has certain usage restrictsions for these forms; for more information, visit LEED Online and click "Sample Forms Download."

Design Submittal

PencilDocumentation for this credit can be part of a Design Phase submittal.

2571 Comments

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Victoria Watson
Dec 19 2014
Guest
112 Thumbs Up

"Conditioned Space?" - Free cooling with outside air

Project Location: United States

Hi,
I am not sure whether to class mechanical rooms which are free cooled by outside air as "conditioned" for the purpose of the baseline (so the baseline would be on system 5 in this example). They are being maintained to 85oF through the use of an AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. (no heating or cooling coil).

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Marcus Sheffer LEED Fellow, 7group Dec 22 2014 LEEDuser Expert 46361 Thumbs Up

No heating or cooling system means that the space is unconditioned.

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Francesco Passerini engineer leedme.it
Dec 19 2014
Guest
1087 Thumbs Up

External lights Interpretation 10236

For some external lights the LEED team claimed the LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org. 10236 for SSc8, i.e. the lights were not considered because:

Street lighting that is required by governmental authorities to be installed within the LEED project, specifically for the purposes of lighting a public street, does not need to be included in any of the calculations. Project teams should provide documentation of the government requirement and a narrative describing the application of this exemption to the project.
www.usgbc.org/leed-interpretations?keys=10236

That interpretation doesn't mention prerequisite EAp2, therefore I think that I have to consider those lights in the energy model, haven't I? Shall the relative lights in the baseline model be modeled as normal external lights (i.e. according to Table 9.4.5) or as process energy (i.e. the wattage of the baseline model is equal to that one of the design model)?

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Marcus Sheffer LEED Fellow, 7group Dec 19 2014 LEEDuser Expert 46361 Thumbs Up

Existing exterior lighting within the LEED project boundary connected to the project (or any adjoining project on a campus project) should be modeled identically in both models. If the existing lighting is not at all connected then it should not be included in the models at all.

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Ritwik Kakati Dagher Engineering, PLLC
Dec 18 2014
Guest
60 Thumbs Up

New Construction vs Major Renovation

Project Location: United States

Our project consists of renovation of 140,000 SF of an existing building, as well as the addition of 30,000 SF of new space. For whole building energy simulation, I see minimum requirement of 10% improvement for new buildings and 5% for major renovations. I'm trying to determine which requirement applies to our project - can our project be considered as a major renovation, or it has to be considered as a new construction?

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Marcus Sheffer LEED Fellow, 7group Dec 18 2014 LEEDuser Expert 46361 Thumbs Up

It is both.

The percentage savings related to the points will be based on a weighted average of the new vs existing. The EAc1 form automatically calculates the percent savings and awards the correct points. In your case the savings threshold for the first point would be 5.88%.

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Ritwik Kakati Dagher Engineering, PLLC Dec 19 2014 Guest 60 Thumbs Up

Thanks!

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Charalampos Giannikopoulos Founder DCarbon
Dec 18 2014
LEEDuser Member
100 Thumbs Up

Mandatory provision 5.4 for existing building

For an existing building under major renovation would the mandatory provision 5.4.3.4 for vestibules be still applicable even if the project scope does not include any additions or plan modifications?

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Marcus Sheffer LEED Fellow, 7group Dec 18 2014 LEEDuser Expert 46361 Thumbs Up

In general if you are not replacing or modifying the system in question you do not need to meet the mandatory requirements related to that system. So I do not think this would be required.

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Charalampos Giannikopoulos Founder, DCarbon Dec 18 2014 LEEDuser Member 100 Thumbs Up

Thanks Marcus for pointing this out!

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Panupant Phapant SCG Cement - Building Materials Co.,Ltd.
Dec 18 2014
LEEDuser Member
121 Thumbs Up

Process load significantly lower than 25%

Project Location: Thailand

The overall process load of our project turns out to be in the vicinity of 15% only. We are aware that 15% is absurdly low and unusual for plants. The factory owner, nevertheless, sent us a full array of appliances and affirmed the list is determinate.
Should I just proceed with the obtainable data and have the factory owner undersign the equipment list so as to substantiate the data?
Thank you very much.

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Francesco Passerini engineer, leedme.it Dec 18 2014 Guest 1087 Thumbs Up

Could you visit the factory, to see all the equipment, plants, etc...?
Could you get bills, in order to analyse the real energy requirements?
I got such a low process load consumption for a school and I explained it with a narrative, but for a factory it seems strange. Are the machines very few in comparison with the building surface? What are the main end uses (heating or cooling, or lighting, or ventilation?).

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Marcus Sheffer LEED Fellow, 7group Dec 19 2014 LEEDuser Expert 46361 Thumbs Up

What does the factory make? Some processes are far more energy intensive than others.

It could be possible to document a low process load, so you can proceed as you suggest. If it were me I would be asking the factory owner a whole bunch of questions about the equipment if I had any doubts about getting it all. Make sure to thoroughly document the actual installed equipment as this will be viewed by the reviewer with considerable suspicion.

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Panupant Phapant SCG Cement - Building Materials Co.,Ltd. Dec 19 2014 LEEDuser Member 121 Thumbs Up

Thank you so much for all the suggestions. The factory is under construction and will manufacture cosmetics as soon as the construction concludes. The owner invariably asserted all the machines had been incorporated.
The owner's substantiation may dispel the reviewer's doubts. In any case, we are a little apprehensive about the discrepancy.

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Jean Marais b.i.g. Bechtold DesignBuilder Expert Dec 19 2014 LEEDuser Member 9093 Thumbs Up

A good place to look is on the electrical equipment schedules...the electrical engineer has to plan after all and requires a list of electical equipment with connection and usage power.

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Praveen Raj Energy Analyst
Dec 17 2014
Guest
3 Thumbs Up

How to prove compliance with Mechanical Ventilation

Project Location: India

The project is a medium sized workshop shed and will be mechanically ventilated with fans with a particular air change per hour as per the local standards. The client wants this to be LEED certified building and we wanted to check what should be the right approach towards energy modeling to meet the EA Prerequisite 2 and EA Credit 1. Normally for a naturally ventilated building we would follow the approach mentioned in the Advanced Energy Modeling Guide, Appendix D. However this is not a naturally ventilated space, though there are windows opened to allow the air changes, with mechanical fans to meet the ventilation requirement. Shall we then model the base case with the same ventilation fans as the design case and prove compliance. Please let us know which CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide/ guide could tell us more about this. Please advise.

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Francesco Passerini engineer, leedme.it Dec 17 2014 Guest 1087 Thumbs Up

G3.1.2.5 Ventilation: "Minimum outdoor air ventilation rate shall be the same for the proposed and baseline building designs".
Actually I model exactly the same ventilation flows and the same schedules in the two models, for every hour. What does "minimum" mean in this case?
I know that an exception could be when in the proposed building there is Demand Control Ventilation.
The fans are modeled as designed for the proposed model, according to G3.1.2.9 for the baseline model.
I hope this is useful to you.

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Marcus Sheffer LEED Fellow, 7group Dec 17 2014 LEEDuser Expert 46361 Thumbs Up

If the space is heated then the baseline should be modeled as a system 9 or 10 under addendum dn to 90.1. The fan power in the baseline 0.3 watts/cfm.

If the space in unconditioned then the ventilation fans are considered a process load and modeled identically.

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Jean Marais b.i.g. Bechtold DesignBuilder Expert Dec 17 2014 LEEDuser Member 9093 Thumbs Up

The standard requires the same infiltration and window ventilations be employed on both models. I would not recommend trying to take credit for window, "natural", or infiltration ventilation unless you are an expert and have a lot of time to prove your case.

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Praveen Raj Energy Analyst Dec 18 2014 Guest 3 Thumbs Up

Thanks for your prompt response.
For your information, we have considered an air-change of 15 achAir changes per hour: The number of times per hour a volume of air, equivalent to the volume of space, enters that space. for effective ventilation for the shed.
There is no demand control ventilation and no heating. The windows shall be kept open to facilitate this 15 ach ventilation. This is may be comparable to mechanically assisted natural ventilation.
Shall we model the baseline with the fans as process load but without any baseline air-conditioning system and likewise for the design case.
Or do we have to model the baseline with the baseline HVAC system types with the 15ach ventilation rate and similarly for the design case. This approach due to the very large ventilation rate will give us absurd figures.
We would like to meet only the prerequisite and not try for any points.
Request your advise and are there any references to ratify this approach ?

Praveen

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Marcus Sheffer LEED Fellow, 7group Dec 18 2014 LEEDuser Expert 46361 Thumbs Up

This is an unconditioned space so any energy use associated with ventilation should be identical in both models. The fan power and ventilation rate would therefore also be identical. No HVAC required in the baseline for an unconditioned space.

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Praveen Raj Energy Analyst Dec 20 2014 Guest 3 Thumbs Up

Many thanks.
May I request any reference document mentioning this.

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Marcus Sheffer LEED Fellow, 7group Dec 22 2014 LEEDuser Expert 46361 Thumbs Up

I am not sure if there are any interpretations that address this but I would have to search them just like you.

Quite often these kinds of issues are not directly addressed but must be determined based on definitions and a connect-the-dots interpretation of 90.1. In this case these fans are not regulated so it is kind of hard to point you to something that is not addressed by the standard in question.

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Panupant Phapant SCG Cement - Building Materials Co.,Ltd.
Dec 17 2014
LEEDuser Member
121 Thumbs Up

Heat gain originating from hooded equipment in energy modeling

Project Location: Thailand

I am doing energy simulations for a factory. I am seeking advice as to the following situation:

1.) Part 1: Load Estimating, Chapter 7 of the classic Carrier Manual states that “a properly designed positive exhaust hood reduces the sensible and the latent heat gains by 50%”. Supplemental data is shown in table 7 – Heat gain from miscellaneous appliances.

Inquiry: Could I simply multiply the appliance wattage by 0.5 to obtain room sensible heat gain?

2.) The factory equipment takes a substantial portion of cooling demand. Therefore, the HVAC designer proposes once-through configuration of supply airflow to equipment room. That is, no room air in equipment room will return to the air handler and end up as a load on the chiller plant. The designer calculated the amounts of exhaust air and make-up air associated with the hood that will keep up desired pressure differential across the room enclosure.

For instance, 4-kW equipment should impose 2-kW heat gain. Suppose that the 2-kW heat gain will warm up the supply air temperature from 13.9 ⁰C (57 ⁰F) to 25 ⁰C (78 ⁰F). The room air at 25 ⁰C (78 ⁰F) will be constantly discharged through the hood whenever the hooded equipment runs.

Inquiry: Regarding energy simulations, could I entirely eliminate the heat gain from hooded equipment as the once through configuration is utilized together with hood? Just additional fresh air load is relevant because, for example, 250 l/s (500 cfm) of once-through make-up air to equipment room is equivalent to 250 l/s (500 cfm) of fresh air to the air handler.

I am grateful for all the advice.

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Marcus Sheffer LEED Fellow, 7group Dec 17 2014 LEEDuser Expert 46361 Thumbs Up

1. Maybe. We would recommend that you double check the Carrier guidance with the guidance in the latest ASHRAE Fundamentals Handbook. There is guidance on hooded and not hooded heat gains.

2. The equipment is still a cooling load in the space, even though it is not a load directly on the cooling coil. it can be reduced but not eliminated entirely. When reducing it you should provide an explanation for how you determined the level of reduction.

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Panupant Phapant SCG Cement - Building Materials Co.,Ltd.
Dec 16 2014
LEEDuser Member
121 Thumbs Up

VAV Fan control for baseline system 6

Project Location: Thailand

We have a rough time seeking to reduce supply fan energy during energy simulations. Could anybody throw some light on the following account:

1.) The project on hand is a plant that strictly regulates pressure differences among interior spaces.
2.) The proposed design reckons with a VSD on the air handler fan to adjust fan speed as airflow drops due to loaded filters, clogged cooling coils, etc. In contrast to generic VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. systems, the VSD on the air handler fan is not designed to vary supply airflow in proportion with room sensible heat.
3.) System 6 requires that the fan control be VAV. As far as I am concerned, the VAV of system 6 does not reflect the actual operation since modulating the supply airflow according to the room sensible heat may not concomitantly control the relative pressure differences among interior spaces.
4.) As a consequence, the fan energy of the proposed design is considerably higher than that of the baseline case.

Is the table G3.1.1B in Appendix G an ironclad rule to follow?
Is it relaxed in case the baseline is not comparable with the actual operation?
Is there a minimum flow of VAV deemed effective to maintain relative pressure differences among internal spaces?

In the event VAV is applicable to the factory in question, I suspect that both the proposed and baseline fans may not save significant energy, not to mention a barrage of pressure sensors and complex controls to make the system run as intended.

Thank you very much in advance for all the responses.

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Marcus Sheffer LEED Fellow, 7group Dec 17 2014 LEEDuser Expert 46361 Thumbs Up

Yes you must follow Appendix G generally without exceptions.

I would suggest you see if G3.1.1 Exception (c) applies to your situation. If it does then your VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. issue goes away.

In general make sure you are not trying to get the baseline system to actually function the same way as the proposed. Quite often the baseline system configuration will not actually work in the real world.

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Panupant Phapant SCG Cement - Building Materials Co.,Ltd. Dec 18 2014 LEEDuser Member 121 Thumbs Up

Thank you very much indeed, Marcus. Your suggestion hit the bull's eye.The exception (C) under G3.1.1 is germane to our situation.

The factory under consideration has three (3) levels of pressurization at 12 Pa (0.05”), 25 Pa (0.1”), and 38 Pa (0.15”).

A multitude of spaces are pressurized to maintain 12.5 Pa (0.05”) and these spaces are contiguously located. Concerning the baseline case, am I allowed to lump these spaces together and cool them by a good-sized PSZ-HP (packaged rooftop heat pumpA type of heating and/or cooling equipment that draws heat into a building from outside and, during the cooling season, ejects heat from the building to the outside. Heat pumps are vapor-compression refrigeration systems whose indoor/outdoor coils are used reversibly as condensers or evaporators, depending on the need for heating or cooling. In the 2003 CBECS, specific information was collected on whether the heat pump system was a packaged unit, residential-type split system, or individual room heat pump, and whether the heat pump was air source, ground source, or water source.) of system 4? In other words, this single zone consists of multiple spaces.

Does each space need to be equipped with a PSZ-HP, making every zone a 1-space zone?

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Marcus Sheffer LEED Fellow, 7group Dec 18 2014 LEEDuser Expert 46361 Thumbs Up

See G3.1.1. For a system 4 you need to map the systems to the proposed systems. Also see Table G3.1-7 about thermal blocks.

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Vassil Vassilev Manager Termoservice OOD
Dec 15 2014
LEEDuser Member
24 Thumbs Up

CS 2009 EAp2-c1 ACP spreadsheet

Greetings,
In the project I'm modeling (C&S), I took the opportunity to use the CS 2009 EAp2-c1 ACP spreadsheet with integrated calculator.
I've come to reach 46% of Energy cost influenced by CS Owner. The spreadsheet (together with the necessary explanations) could be uploaded in EAp2 and also in EAc1 form upon ACP section.
The question is: How to enter the revised points (for example 7 instead of 5). I don't see such place on the forms. The same question is also for the renewable energy, because it should also be influenced by the same percentage.
Thanks.

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Marcus Sheffer LEED Fellow, 7group Dec 15 2014 LEEDuser Expert 46361 Thumbs Up

It depends on what version of the form you are using (v3, v4 or v5).

I don't think you have to enter the revised points. The reviewer should be able to figure it out and award the correct number of points.

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Charalampos Giannikopoulos Founder DCarbon
Dec 11 2014
LEEDuser Member
100 Thumbs Up

Existing Building Fenestration

According to ASHRAE 90.1-2007 Table G3.1.5 (f) for existing building envelopes, the baseline building design shall reflect existing conditions prior to any revisions that are part of the scope of work being evaluated. Does this mean that for an existing fully glazed building (80% of gross above-grade wall area) the baseline building will meet the same portion of fenestration (80%)?

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Marcus Sheffer LEED Fellow, 7group Dec 11 2014 LEEDuser Expert 46361 Thumbs Up

If the existing building is 80% then the baseline would be 80% assuming the renovation remained at 80%. If the glazing area was reduced during the renovation then the baseline glazing area would also be reduced.

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Charalampos Giannikopoulos Founder, DCarbon Dec 11 2014 LEEDuser Member 100 Thumbs Up

Thank you Marcus!

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Omar ElRawy Building Engineer, LEED AP BD+C EA Building Consultants
Dec 11 2014
Guest
594 Thumbs Up

System 8 Fan Power Allowance

Dear All,
I have a system 8 (VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. with PFP boxes) baseline and I had a reviewer's comment stating that: "The interior fan demand reported in Table EAp2-4 for the Baseline case exceeds the Baseline fan power allowance reported in the Supplemental Table 1.4".

Knowing that the values entered to Table EAp2-4 were enduse values generated by the simulation tool for all vent fans (including zones pfp), and Knowing that I tried changing Table 14 System from VAV with pfp to VAV with reheat to find that fan power allowance didn't decrease; meaning that the table isn't counting for the zones' PFP powers;

Should I supply a narrative explaining that the PFP fan powers did cause this increase, or there is a certain check that I'am missing?

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Marcus Sheffer LEED Fellow, 7group Dec 11 2014 LEEDuser Expert 46361 Thumbs Up

I provided a response to this issue in the previous discussion where you also posted the same question.

http://www.leeduser.com/credit/NC-2009/EAp2?page=3#comment-55098

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Omar ElRawy Building Engineer, LEED AP BD+C, EA Building Consultants Dec 11 2014 Guest 594 Thumbs Up

Thanks

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Yastimy Jupson Green Building Consultant
Dec 09 2014
Guest
2 Thumbs Up

Evaporative Chiller in EAp2?

Project Location: China

Hello everyone,
i'm now joining a LEED project and the owner wants to use 50RT evaporative chiller in their building, but in ASHRAE standard 90.1, i cannot find the mandatory part for evaporative chiller, could i use water-cooled chiller standard to comply with ASHRAE mandatory part? or we cannot use evaporative chiller in LEED project?Tthanks!

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Jean Marais b.i.g. Bechtold DesignBuilder Expert Dec 10 2014 LEEDuser Member 9093 Thumbs Up

The basic rule is that if the standard does not regulate it, it is the same in both baseline and proposed case models, i.e. both get the proposed case equipment. In my SI Version of 90.1-2007, Table 6.8.1C lists Water Chilling Packages-Minimum Efficience Requirements for Equipment Type "Air colled, with condenser, electrically operated" as 2.80 COP and 3.05 IPLV (as long as the chilled water temp is more than 4.4ºC). The size category says "All capacities", so that covers your 50RT.

If your chiller has a seperate conderser unit, then you're looking at tables 6.8.1H,I,J for the chiller TOGETHER WITH 6.8.1G for the condenser unit (Heat Rejection Equipment). You'll have to figure out if 50RT is IP or SI units and get the match in the tables. If it's not there, then it's not regulated.

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Marcus Sheffer LEED Fellow, 7group Dec 10 2014 LEEDuser Expert 46361 Thumbs Up

90.1-2013 added significantly more systems so you could check there to see if your system is covered. As Jean said you are not held to a minimum efficiency if the system is not covered under 90.1-2007 but if you are looking for a minimum to use you might find it in the newer version.

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Vassil Vassilev Manager Termoservice OOD
Dec 09 2014
LEEDuser Member
24 Thumbs Up

Table 1.4.7B Entering Outdoor Airflow in Baseline

Project Location: Bulgaria

Greetings,
There is a clarification issue while entering these values in the Baseline about which I'd appreciate some advice.
The OA flow should be identical in both models. When calculating the HVAC systems in Baseline (system 5 or 7), and since these are multiple-zone systems, the OA is corrected at the end by Ev and with exception of Ev=1 the OA which is calculated (corrected Vot) is bigger. In Propose case however almost always the Ev is different, in most of the cases bigger than the Baseline one.
The question is: should I enter the uncorrected OA flow in both cases, in order in the table these values to appear equal, besides this way it will reflect exactly the project design.
Thanks.

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Marcus Sheffer LEED Fellow, 7group Dec 09 2014 LEEDuser Expert 46361 Thumbs Up

The Proposed should be based on the design value and the Baseline should be the same in all areas without DCV.

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Vassil Vassilev Manager, Termoservice OOD Dec 09 2014 LEEDuser Member 24 Thumbs Up

Thanks for the reply.
However it's kind of unclear to me the comment about DCV.
As I've tried to say, the only way the OA to appear identical in both Proposed and in the Baseline is to enter the uncorrected OA value in accordance to ASHRAE 62.1 terminology. The question was am I right in such suggesting.
Thanks.

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Marcus Sheffer LEED Fellow, 7group Dec 10 2014 LEEDuser Expert 46361 Thumbs Up

No DCV - model OA identical based on the actual equipment designed/installed. If the equipment is designed with 1,000 cfm of OA then that is what gets modeled.

With DCV - again model the proposed based on the actual equipment designed/installed. The baseline OA is modeled using the ASHARE 62 calculation for the proposed and this should be the same as the Vot calculated for IEQp1.

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Vassil Vassilev Manager Termoservice OOD
Dec 04 2014
LEEDuser Member
24 Thumbs Up

EAp2 Online form - Table EAp2-1. Space Usage Type -

Greetings,
There is a clarification question associated with a reviewer's remark.
From the modeling software (Trace 700) reports, the spaces are divided to Regularly occupied and Unconditioned (as shown also in the EAp2-1 form). In the column of Regularly occupied, the software report practically is listing the conditioned spaces and we are entering them in the same way in the form.
There is however a conflict, because according to other credits, some of these spaces are not considered as regularly occupied. This is for stairs, active storage areas, corridors, which according to IEQp1 are also considered as unoccupied - meaning that there are no persons there (Rp = 0). There are also spaces like museums, which also could not be considered as regularly occupied, because the people are just passing there.
The question is:
in this table (EAp2-1) which areas to enter - the ones from the modeling report (which is practically the conditioned areas) or the areas established in PI forms.
Thanks.

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Marcus Sheffer LEED Fellow, 7group Dec 04 2014 LEEDuser Expert 46361 Thumbs Up

The information in this table should be consistent with the information entered for other credits. If it is not consistent then provide an explanation for why it is not consistent. There can be legitimate reasons why there would be some variation.

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Vassil Vassilev Manager, Termoservice OOD Dec 04 2014 LEEDuser Member 24 Thumbs Up

Thanks for the reply.
For sure there has to be consistency, but getting back to my question, I'll rephrase it like this:
If in table EAp2-1, in the Regularly occupied spacesRegularly occupied spaces are areas where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building. column, the entered areas are consistent with other credits, but are not consistent with modeling software report (in respect if they are conditioned or unconditioned), should this be a problem with all of the remaining info of credit EAp2 or does this table (EAp2-1) really matters with energy saving analysis and calculations of EAp2 credit.
Thanks

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Marcus Sheffer LEED Fellow, 7group Dec 04 2014 LEEDuser Expert 46361 Thumbs Up

This is just more consistency. The information should be consistent across all documentation for all credits. If it is not then explain why it is not.

So yes it could matter. The information entered in this table does matter relative to EAp2. It is often used to double check modeling inputs for consistency within the documentation for EAp2.

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Vassil Vassilev Manager, Termoservice OOD Dec 04 2014 LEEDuser Member 24 Thumbs Up

Hi Marcus, thanks very much for your explanation.
There is however something which still kind of sounds controversial to me. This is when there is a space, which is considered as unoccupied like corridor and in the same time is conditioned. As there is no sure statement whether to entered it or not in the EAp2-1 table in such cases, this appears to be an area which is always potentially open for reviewer remarks, because in every such case there could be a remark for explanations to be provided or may be I'm getting something wrong.
Your comment would be highly appreciated.
Thanks

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Marcus Sheffer LEED Fellow, 7group Dec 04 2014 LEEDuser Expert 46361 Thumbs Up

Ok. Specifics help my understanding of your issue. I see your confusion now.

Since Table EAp2-1 does not separate conditioned and unconditioned (which is how it should be set up), I would but the conditioned corridor in the regularly occupied area even though they do not meet the definition of regularly occupied for the other credits. If you provide sufficient breakdown by space usage type the reviewer should be able to see which of the conditioned spaces you entered in the "regularly occupied area" column are really regularly occupied.

Every reviewer is a different person who tends to concentrate on slightly different issues. When I review this credit I do not look for consistency between the information in Table EAp2-1 and some of the other credits that are based on regularly occupied spacesRegularly occupied spaces are areas where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building. for the very reasons that you are pointing out. Perhaps your reviewer saw something specific that led them to question this information, hard to say.

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Omar ElRawy Building Engineer, LEED AP BD+C EA Building Consultants
Dec 03 2014
Guest
594 Thumbs Up

Separating Pantry Zone

Project Location: Egypt

Dear all,
I have a case where I need to know if I should model separate Pantry zone in Both Basecase and Proposed Case, or in Basecase only?

I have an office building with one System 8 per floor in Basecase. and one AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. with multiple VAVs in proposed case. Each floor has one FCU for its pantry zone in the proposed case.

I need to know if I have to model this pantry separately in the proposed case only, in both proposed case and basecase (with a system 4 in Basecase), or I can neglect this zone and assume it follows the rest of the floor as it is only?

Another question is: on the basement floor I have 4 zones (entrance lobby, driver room, UPS room, and Prayer room) each is served by one FCU in the proposed case. Can I gather these four spaces as one (System 4) in Basecase, and one FCU in the proposed case? or they should be separated into 4 zones (thermal blocks)?

Thanks

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Marcus Sheffer LEED Fellow, 7group Dec 03 2014 LEEDuser Expert 46361 Thumbs Up

The proposed is modeled as designed.

The baseline per Appendix G. You should only model a separate zone for the pantry if one of the exceptions to G3.1.1 applies.

The rules for creating thermal blocks are spelled out in Table G3.1-7. Based on your descriptions it does not sound like you can consolidate those zones. If your building is a system 8 then the basement floor should also be a system 8 unless one of the exceptions to G3.1.1 applies.

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Vassil Vassilev Manager Termoservice OOD
Dec 03 2014
LEEDuser Member
24 Thumbs Up

Supplemental Table 1.4 - reviewers comment

Greetings,
I've received a comment from a reviewer, that insufficient info regarding VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. reheat terminal units are provided in this table. I've been checking over again and I didn't find a place where such info could be entered. The only way I see, is to upload the input value report from the modeling software or to cut a printout from the entering screen of the software.
Is this acceptable or there are other options.
The other question to this Table 1.4 is regarding the LEED v4. According to it, the ASHRAE version is to be 90.1-2010. In the last downloadable version of this Table 1.4 however, in the Instruction tab is written that ASHRAE 90.1 2007 is to be addressed. Is there a latest version on Table 1.4 which is addressing ASHRAE 90.2010.
Thanks.

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Marcus Sheffer LEED Fellow, 7group Dec 03 2014 LEEDuser Expert 46361 Thumbs Up

It should be entered in the Other (Describe) area at the bottom of Table 1.4.7B. Sounds like either or both methods would work. It is always a good idea to provide evidence of what was modeled from the software as opposed to just entering a number in a form, especially if you want to make sure that there is no doubt in the reviewer's mind.

There is a version of this table being used for LEED v4 projects. See - http://www.usgbc.org/sampleforms

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Vassil Vassilev Manager, Termoservice OOD Dec 03 2014 LEEDuser Member 24 Thumbs Up

Thanks for the reply.
I've checked meanwhile the site where you've mentioned I'd find the Table 1.4 used for LEEDv4, but didn't find it.
Is this table have a new reference name?
Thanks

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Marcus Sheffer LEED Fellow, 7group Dec 03 2014 LEEDuser Expert 46361 Thumbs Up

They actually combined the energy modeling results and the section 1.4 tables into one calculator. It is called the Minimum Energy Performance Calculator in the link.

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Khaled Fouda
Dec 01 2014
LEEDuser Member
21 Thumbs Up

Any HAP Expert?

Project Location: United States

I use Carrier-HAP and according to ASHRAE 90.1 G.1 #4, all baseline HVAC fans should be running continuously when the space is occupied and cycled when the space is unoccupied. However, I have some systems that follow exception (a). Any hint how to apply this?

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Marcus Sheffer LEED Fellow, 7group Dec 01 2014 LEEDuser Expert 46361 Thumbs Up

A HAP subscription comes with customer service included so you can call/email them directly. There is also a HAP Users discussion forum at onebuilding.org.

If it is for a heating only space model a system 9 or 10 from ASHRAE 90.1-2010 which is allowed via addendum dn. Another way way to deal with the no heating/no cooling system situation is to set the temperatures in the spaces so that the system never comes on in the first place. There are ways around the situation of not having a heating or cooling system in a space.

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Vassil Vassilev Manager Termoservice OOD
Dec 01 2014
LEEDuser Member
24 Thumbs Up

Exterioir Lighting - Non tradable

Greetings,
In the project I'm modeling, in the Proposed project there is a Building facades exterior lighting which LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. is bigger than the allowed values of 0.2 W/ft2. This lighting however is a special illumination which is controlled by separate control device independent of the other lighting systems.
The question is: How to enter it in the Table 1.4.3B.
Thanks.

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Marcus Sheffer LEED Fellow, 7group Dec 01 2014 LEEDuser Expert 46361 Thumbs Up

Non-tradable is modeled identically. If the proposed is greater than the Baseline allowance then model the same value as in the proposed in the baseline. Make sure your total exterior lighting is less than the overall baseline allowance (tradable + non-tradable) since exterior lighting is a mandatory provision.

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Vassil Vassilev Manager, Termoservice OOD Dec 01 2014 LEEDuser Member 24 Thumbs Up

Thanks for the reply.
I've checked the total value and no matter that the Proposed facade is bigger then allowed, the total is less then the Baseline totals.
At such situation which value to enter in the simulation - the project one or the max allowed.
Thanks.

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Marcus Sheffer LEED Fellow, 7group Dec 01 2014 LEEDuser Expert 46361 Thumbs Up

For the non-tradable the value should be identical based on the proposed value. For the tradable model the proposed as designed and the baseline per the ASHRAE allowance.

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Vassil Vassilev Manager, Termoservice OOD Dec 02 2014 LEEDuser Member 24 Thumbs Up

Thanks for the reply.
Final question to this issue:
If finally lighting facade of the Proposed makes the total exterior lighting bigger than BAseline, but in the same time the Proposed facades lighting is with characteristic corresponding to the exceptions specified in 9.4.5 b, how to enter the data in the table 1.4.3.B and refer to the mentioned exception .
Thanks

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Marcus Sheffer LEED Fellow, 7group Dec 02 2014 LEEDuser Expert 46361 Thumbs Up

In general facade lighting would not qualify under 9.4.5b unless it is illuminating a sign.

If some of the exterior lighting qualifies under a 9.4.5 exception then it gets modeled identically in both models. Information on the exempted lighting would get entered in the Additional Notes box below the exterior lighting tables in Section 1.4.3B. Fully explain the purpose and area coverage as well as the wattage. If this covers a large area you should consider providing a separate document to explain how it qualifies for the exception.

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Vassil Vassilev Manager Termoservice OOD
Nov 28 2014
LEEDuser Member
24 Thumbs Up

DCV modeling

Greetings,
The project I'm modeling has several DOA AHUs. Every AHU has a single CO2Carbon dioxide sensor located on the return duct next to the unit. There are however AHUs which are serving several different rooms, but the CO2 sensor is only one on the assembly part of the return duct.
Should such units be modeled as DCV.
There is another question to this issue. The number of people in the room (occupancy) is defined by the designers and these numbers do not coincide with min ASHRAE 62.1 rates (they are smaller). The OA air flows however, for both Proposed and Baseline are equal. Also the air quantity (cfm/pers & cfm/ft2) is as per ASHRAE 62.1 rates, only the Occupancy Density - not. The question is (in respond to the reviewers remark): How to make Baseline to reflect ASHRAE 62.1 min. rates whereas the OA is already defined by the Proposed and the occupant density do not coincide with ASHRAE 62.1 default values.
Your advice on the matter will be highly appreciated.
Thanks.

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Marcus Sheffer LEED Fellow, 7group Dec 04 2014 LEEDuser Expert 46361 Thumbs Up

In the system that serves multiple spaces with a CO2Carbon dioxide sensor in one of the returns, you should only model DCV in the space served by the sensor and not in the other spaces.

Do not use the ASHRAE default occupancy if you know the actual occupancy. The proposed outside air should be based on the design for all systems, in all cases. The Baseline outside air should be based on the ASHRAE 62,1-2007 calculated outside air from the corresponding system in the proposed if the proposed system has DCV. If it does not have DCV then the baseline is identical to the proposed.

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Ghaith Moufarege
Nov 26 2014
LEEDuser Member
8332 Thumbs Up

USGBC DES Guidance - Option 1

Dear All,

I just want to verify one thing regarding DES Option 1 (building stand-alone scenario):

The cooling & heating are modeled as purchased energy (with identical energy rates $) in both the baseline and proposed. This means that if I want to claim savings in my proposed scenario, I can achieve this by having more energy efficient lighting and higher efficiency HVAC fans inside my building.

Additionally, if my proposed building has a better insulated envelope (and perhaps lower lighting), then the total proposed HVAC demand will be lower than that of the baseline, and the HVAC energy consumption will be proportionally lower (given that there is no efficiency / COP factor in purchased energy). Is this correct?

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Francesco Passerini engineer, leedme.it Nov 26 2014 Guest 1087 Thumbs Up

Yes, in my opinion it is correct. I used that option and some savings were due to the fact that the proposed model was cooled and heated through radiant systems. In fact, energy transfer through water requires less energy than through air systems.
Best Regards

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Marcus Sheffer LEED Fellow, 7group Nov 30 2014 LEEDuser Expert 46361 Thumbs Up

Sounds right to me too.

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Rathnashree Bharadwaj
Nov 26 2014
Guest
4 Thumbs Up

Baseline for Interior glass

What should be the baseline for interior glazing such as for atrium and partitions? Generally, the designed case will be SGU with high U value and SHGCSolar heat gain coefficient (SHGC): The fraction of solar gain admitted through a window, expressed as a number between 0 and 1..

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