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.

2347 Comments

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Marcus Sheffer LEED Fellow, 7group Nov 01 2013 LEEDuser Expert 41683 Thumbs Up

Unconditioned spaces (no heating or cooling) are modeled identically in both cases.

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Ivan Souza Sustainability Consultancy Services, Cushman & Wakefield Nov 01 2013 LEEDuser Member 842 Thumbs Up

So, how can I gain in energy savings in occupied spacesOccupied Spaces are defined as enclosed spaces that can accommodate human activities. Occupied spaces are further classified as regularly occupied or non-regularly occupied spaces based on the duration of the occupancy, individual or multi-occupant based on the quantity of occupants, and densely or non-densely occupied spaces based upon the concentration of occupants in the space. where I have natural ventilation?

For example, in a meeting room I use natural ventilation (proposed). My baseline should not have an air conditioning system?

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Jean Marais b.i.g. Bechtold DesignBuilder Expert Nov 01 2013 LEEDuser Member 8331 Thumbs Up

1) Make sure not to confuse the fuctions of VENTILATION with CONDITIONING
2) If your zone is not conditioned, think of other end-users in the zone such as
- lighting
- heated water use
- process & plugloads

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Ivan Souza Sustainability Consultancy Services, Cushman & Wakefield Nov 01 2013 LEEDuser Member 842 Thumbs Up

What do you mean with " not to confuse the fuctions of VENTILATION with CONDITIONING"?

Thanks!

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Jean Marais b.i.g. Bechtold DesignBuilder Expert Nov 01 2013 LEEDuser Member 8331 Thumbs Up

- Ventilation is concerned with the fresh air amount for breathing.
- Conditioning is concerned with the temperature (and possibly humidity) conditioning of the air and surfaces of the zone.

For example, you may ventilate with windows and condition with hotwater radiators.

As soon as you condition, you must model a baseline conditioning system. Except for demand ventilation systems, the outdoor air ventilation rates of both baseline and design models must match, regardless if that outdoor air comes from windows or mechanical systems.

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Marcus Sheffer LEED Fellow, 7group Nov 01 2013 LEEDuser Expert 41683 Thumbs Up

Guidance on modeling natural ventilation for savings is found in Appendix C (I think) of the Advanced Energy Modeling Guide for LEED which can be found on the USGBC web site.

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Matt Scott Engineer N.E. Fisher & Associates, Inc.
Oct 31 2013
Guest
236 Thumbs Up

Section 1.4 Tables - Table 1.4.2A (Vertical Glazing)

Table 1.4.2A (Shading & Orientation) asks for the Above-Grade Wall & Vertical Glazing Area by Orientation. Does the vertical glazing area include glass in exterior doors?

The reason why I ask is because the HAP LEED report seems to only indicate Window Area and Gross Wall Area, which will create a bit of a discrepancy in the Section 1.4 Tables.

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Marcus Sheffer LEED Fellow, 7group Nov 01 2013 LEEDuser Expert 41683 Thumbs Up

Yes it does include the glass in doors. It asks for vertical glazing area not just window area.

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Luana Bertoletti Sustentech
Oct 31 2013
Guest
650 Thumbs Up

HVAC system - Proposed model - Part of system provided

Hi,

I have a doubt related to how to model the proposed system when only part of the system is provided for some areas.

In a specific project, most of the areas have the HVAC system already designed. It consists of a water-cooled VRF system. However, in some areas, it was provided only the condensing water, not the evaporators.

My question is: how should I model the HVAC system in the proposed model in these areas, for which the terminal units were not provided?

Another scenario that I'm not sure about is: if I have a 10-story building, for which the HVAC system has been designed only for 8 stories, should I model the 2 other stories as having no HVAC system?

Thanks!

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Marcus Sheffer LEED Fellow, 7group Oct 31 2013 LEEDuser Expert 41683 Thumbs Up

If the system in some areas has not been designed it must be modeled identically to the baseline. See Table G3.1-1 Proposed (c).

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Luana Bertoletti Sustentech Oct 31 2013 Guest 650 Thumbs Up

Hi Marcus,

In the first example I've mentioned, in which part of the system is already defined, what would be left to de modeled "exactly as they are in the baseline building"? The fans?

In the second example I have another doubt: According to Appendix G, the HVAC system for the baseline model would be #8, which consists of a chiller plant. In my proposed case, in the 2 stories for which no HVAC system has been specified, should I model the HVAC system as being #8 or according to the requeriments of Table G3.1.1.A, depending on the area and number or stories of the areas which have no HVAC system?

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Marcus Sheffer LEED Fellow, 7group Oct 31 2013 LEEDuser Expert 41683 Thumbs Up

If you can show that the installed piping will be used by the owner or a future tenant (lease agreement) then you could model a minimally efficient VRF system. If not then the entire system must be identical to the baseline.

Identical to the baseline. You do not get to change the baseline based on the smaller space.

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Luana Bertoletti Sustentech Oct 31 2013 Guest 650 Thumbs Up

First example: Understood!

Second example: So, if I have a Baseline Building which uses Baseline system #8 and, for example, 50 m2 of area in my proposed building which doesn't have an HVAC system designed to it, I must model the HVAC system for this area as Baseline system #8?

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Marcus Sheffer LEED Fellow, 7group Nov 01 2013 LEEDuser Expert 41683 Thumbs Up

Yes

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Dónal O'Connor
Oct 30 2013
Guest
96 Thumbs Up

Modeling Commercial Kitchen Energy Usage

Hi all,

I would be grateful if somebody could direct me to any resources that outline how to accurately model commercial kitchen energy usage.

Regards,

Dónal

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Marcus Sheffer LEED Fellow, 7group Oct 30 2013 LEEDuser Expert 41683 Thumbs Up

I thought I provided an answer to this question recently. Did you post it under another credit as well?

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Dónal O'Connor Oct 30 2013 Guest 96 Thumbs Up

Hi Marcus,

No I did not. Can you direct me to your previous answer?

Thanks

Dónal

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Francesco Passerini engineer, leedme.it Oct 31 2013 Guest 1026 Thumbs Up

You could consider table 3.1.13 of the "Buildings energy data book":
http://buildingsdatabook.eren.doe.gov/docs/DataBooks/2011_BEDB.pdf

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Marcus Sheffer LEED Fellow, 7group Oct 31 2013 LEEDuser Expert 41683 Thumbs Up

It will be quicker to try and respond again. I think I sent links the last time but I don't have much time today.

I would check COMNET to see if they have any W/sf values and schedules you could use. LEED for Retail has a table of various kitchen equipment you can use.

We typically have a conversation with the project's kitchen consultant to discuss each piece of equipment. We go over the energy use and operational schedule to produce our estimate of the overall kitchen energy use.

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jorge torres coto Building Systems Commissioning Engineer, Empirical Engineering, LLC Oct 31 2013 LEEDuser Member 353 Thumbs Up

EnergyStar has some extensive excel sheets with baselines that LEED for Retail adopted and you can also input your proposed design to calculate savings vs. Baseline.

You can Google "energy star commercial kitchen calculator" and the excel sheet will come up. LEED for retail also has the reference, though it may be out dated.

fishnick.com also has calculator that LEED for Retail Core Committee utilized for their baselines.

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Dónal O'Connor Nov 04 2013 Guest 96 Thumbs Up

Hi all,

Thank you for your responses, they are greatly appreciated.

Regards,

Dónal

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CONSTANZA CATTAN LEED PROJECT MANAGER E2 CHILE
Oct 30 2013
Guest
17 Thumbs Up

Base case and proposed case modeling

At he moment, we are modeling a buried building with a green roof (as part of the energy efficiency strategy) according to the appendix G of the ASHRAE standard 90.1 (2007)
The question regards the base case and the the proposed one.
The base case model must be buried as well? or it should be modeled as a regular building from ground floor, with the exposed envelope?

Appendix G, table 3.1, "Modeling Requirements for calculating Proposed and Baseline Building PerformanceBaseline building performance is the annual energy cost for a building design, used as a baseline for comparison with above-standard design.", section 5.- "Building Envelope" mentions both must have the same "total gross area of exterior walls".
In section 5 of the mentioned standard, tables 5.5, regarding "Building Envelope Requirements for 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. the item "walls" is composed by "Above Grade" and "Below Grade"
Is it then, the total gross area resulting from the sum of "below grade" and "above grade" walls that should be the same for the base case and the proposed one? or, is it the below grade and above grade independently considered to equal the baseline and proposed case components?

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Marcus Sheffer LEED Fellow, 7group Oct 30 2013 LEEDuser Expert 41683 Thumbs Up

The quantity of above and below grade walls should be the same in both models. So I would model them identical to the proposed in your reported models. Then I would model the baseline again as a regular building with a reasonable mix of above and below grade walls and attempt to claim savings as an exceptional calculation under Section 1.7 of the form. Be sure to provide a justification for your baseline modeling assumptions of above and below grade wall areas. Personally I think it should be eligible for savings and maybe your reviewer will too. If not then it is easy for them to remove this savings without having to make any adjustments.

Not sure if there is an interpretation on this issue but if not and you want and official ruling on the issue you will need to submit one.

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Joe Bouley
Oct 29 2013
Guest
21 Thumbs Up

Baseline System? 110,000 sf building w/ code exh requirement

I'm working on a Vehicle Maintenance Facility that is one-story, 110,000 sf with the following breakdown:

-approx 85,000 sf of indoor parking
-approx 11,000 sf of mechanics bays
-approx 14,000 sf of administrative space (offices)

The indoor parking and mechanics bays require minimum exhaust rates for CO/NO2 emissions, and based on other threads here, I'm assuming that the indoor parking and mechanics bays are considered the "predominant condition." I'm confused as to how each space's baseline system should be addressed.

Based on the overall area, building function, and the fact that we have natural gas would lead me to System 5 being used for the mechanics bays and vehicle parking (the predominant condition), but these spaces have code exhaust requirements and pressurization requirements, which leads me to believe I should be using System 3 (based on G3.1.1c) for these "predominant condition" spaces.

Can anyone provide some guidance? Any help is much appreciated.

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Marcus Sheffer LEED Fellow, 7group Nov 01 2013 LEEDuser Expert 41683 Thumbs Up

Is the indoor parking conditioned space? If not it would not count.

Once you identify the predominant condition then you apply any exceptions and use the area of that space to determine the system type.

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Joe Bouley Nov 04 2013 Guest 21 Thumbs Up

Thanks for the response.

The indoor parking is heated and ventilated--not mechanically cooled.

The predominant condition would be the indoor parking, but G3.1.1(c) would apply to this space and make the indoor parking a PSZ system rather than a Packaged 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 reheat.

The overlying question is: if the predominant condition falls under an exception, does the next condition become the predominant condition?

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Marcus Sheffer LEED Fellow, 7group Nov 04 2013 LEEDuser Expert 41683 Thumbs Up

I would recommend that you apply a system 9 to the indoor parking as a heated only space. If the mechanics bays are heated and cooled then it sounds like the remainder of the project would be a system 5. The use of a system 9 takes you into ASHRAE 90.1-2010. Within that version you would then apply G3.1.1 Exception (f) which says to use a different baseline system for the heated and cooled spaces. If the mechanics bays are not cooled then it is a system 9 too and the office would be a system 3.

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Joe Bouley Nov 04 2013 Guest 21 Thumbs Up

Thanks, Marcus--

This would still apply under ASHRAE 90.1-2007 due to the Addendum "dn", yes? Reason I ask is we're working under LEED v2009 and "dn" covers heating only systems as well.

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Marcus Sheffer LEED Fellow, 7group Nov 05 2013 LEEDuser Expert 41683 Thumbs Up

For LEED you can use any addendum to 90.1 as long as you use it in its entirety. Yes is looks like Addendum dn was the one that added these systems. FYI - this addendum refers to these systems as systems 10 and 11. That was a typo in the addendum and they should be referred to as systems 9 and 10.

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HOUCINE TLEMSANI Mechanical Designer MEP Engineering Solutions, Inc
Oct 25 2013
LEEDuser Member
296 Thumbs Up

Revised Section 1.4 Form Units

Hi
i am working on a project and using the Revised section 1.4 Form since the project was been registered after mars 2013. The lighting part of the Form is a bit confusing. the assumption on the form is that both, proposed and baseline building are modeled base on the space by space or the building area method. this is true for the base line not the proposed. the proposed case is modeled with the actual load.
DO we have to input the lighting power for each space in the building or there is a work around.
the same for the process load side.
any help will be great.

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Marcus Sheffer LEED Fellow, 7group Oct 25 2013 LEEDuser Expert 41683 Thumbs Up

You must use the same methodology for both models. That is why the form does not let you mix them.

Process loads must be identical too. If you want to claim process load savings you must use the exceptional calculation method.

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HOUCINE TLEMSANI Mechanical Designer, MEP Engineering Solutions, Inc Oct 25 2013 LEEDuser Member 296 Thumbs Up

in the base line I am using the building type methodology office building 1 W/sqf. the proposed is modeled as designed in accordance with G 3.1.6.a
in this case i take the total lighting power for the proposed building and divide it by the building SQF and input it in the form as W/sqf for the hole building.

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Marcus Sheffer LEED Fellow, 7group Oct 25 2013 LEEDuser Expert 41683 Thumbs Up

Using the Building Area Method you take the 1 W/sf for the baseline and enter that value for the lighting in each zone. For the proposed you add up the wattage and divide by the sf and then you use that value in your model in each zone. You do not vary the lighting power density per zone as you have in the proposed design. Yes this seems to violate the model as designed requirement but 90.1 is full of these contradictions. In our experience you will generate more energy savings if you use the space-by-space method and it is more accurate. We never use the building area method.

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HOUCINE TLEMSANI Mechanical Designer, MEP Engineering Solutions, Inc Oct 25 2013 LEEDuser Member 296 Thumbs Up

Thanks Marcus

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jane kane
Oct 23 2013
Guest
19 Thumbs Up

Energy modeling for Workshop Building

HI

We have a workshop building targeting for LEED NC.
The whole workshop is covered by one huge roof with TWO small air conditioned lab workshop and the rest of the space is naturally ventilated. ( no envelope)

The two air conditioned lab workshops share the same air cond system but both the spaces are not connected.

How should we access this workshop?
How do we carry out the energy simulation? What should be the envelope or WWR? since the whole workshop doesn't really have an envelope, it's naturally ventilated.

appreciate your help. many thanks

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Marcus Sheffer LEED Fellow, 7group Oct 25 2013 LEEDuser Expert 41683 Thumbs Up

The workshop area without walls is exterior space. The conditioned spaces would be modeled as designed.

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Santiago Rodriguez Director of Energy Efficiency REVITALIZA CONSULTORES
Oct 22 2013
Guest
803 Thumbs Up

Modeling HVAC System #8: VAV with PFP boxes

Dear Forum,

We are modeling a high rise building in order to comply with EAp2 minimum energy performance. The corresponding HVAC system for the baseline design is 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.

Section G3.1.1 of Appendix G of ASHRAE 90.1 2007 states: For systems 5, 6, 7, and 8, each floor shall be modeled with a separate HVAC system. Floors with identical thermal blocks can be grouped for modeling purposes.

So, according to this section, I have to model a VAV system with PFP boxes for each floor (it would have its own chiller, cooling tower, pump and its corresponding air loop). For the project I modeling, this means a lot of work, since we have 23 floors! The floors are not identical in size but have the same thermal zone configuration. Is it acceptable to group them all together?

Many thanks in advance

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Marcus Sheffer LEED Fellow, 7group Oct 22 2013 LEEDuser Expert 41683 Thumbs Up

Your assumption is not quite correct.

You model a central chilled water plant for the whole building including towers, pumps, etc.. You model a system per floor (air handling, chilled water coils, electric heat, etc.). So one central plant with 23 systems (unless you can justify lumping some systems together).

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Santiago Rodriguez Director of Energy Efficiency, REVITALIZA CONSULTORES Oct 22 2013 Guest 803 Thumbs Up

Thank you Marcus I got it clear now. In my opinion section G3.1.1 should be explained in more detail because when it says: each floor shall be modeled with a separate HVAC system, it is not clear that it should exclude the central plant.

Regards,
Santiago

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Pedro Ribeiro Director of Sustainability Edifícios Saudáveis Consultores
Oct 22 2013
LEEDuser Member
676 Thumbs Up

Zone isolation

In an office building, shall meeting rooms (sporadically occupied within the schedule defined for the remaining occupied office areas) be considered an isolation zone according to ASHRAE 90.1 (2007) section 6.4.3.3.4?

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Marcus Sheffer LEED Fellow, 7group Oct 22 2013 LEEDuser Expert 41683 Thumbs Up

No.

The key word in this section is nonsimultaneously. A meeting room in an office will be operated/occupied simultaneously with the office spaces. The idea behind this section is to isolate areas that do not operate at the same time from each other so you are not sending conditioned air to a space that is not occupied on a regular basis.

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Phillip Cook WGE
Oct 22 2013
LEEDuser Member
142 Thumbs Up

Feature lights

We have some external uplights that are used to light statues from below. I presume these go into the calculation as a special feature area which has a baseline unit of 2.15W/m2 - but how do I determine how many m2 a statue uplight covers? At the moment I have just made the power (W) of the baseline and the proposed feature uplight be the equal - which is fine with me if this is fine with the assessors.

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Marcus Sheffer LEED Fellow, 7group Oct 22 2013 LEEDuser Expert 41683 Thumbs Up

Sounds like a geometry problem. The fixture will have a certain spread and be mounted a certain distance from what it is illuminating. I would guess you pick a plane at a reasonable distance and calculate the area. This is just off the top on my head so feel free to correct me if I am wrong.

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JOHANNA SENOTT Architect / Environmental adviser EA Energia y Arquitectura
Oct 21 2013
LEEDuser Member
651 Thumbs Up

EAp1 Review

Hello we´ve submitted a project to review in which we have no conditioned spaces in the proposed case but we modelled the HVAC system the same way in baseline and proposed cases since we dont comply with the criteria for non-conditioned spaces these is the review comment we got:

1. It appears from the narrative provided under PIf4 (Schedules and Overview documents) that no HVAC systems except for ventilation fans are provided for the project building and therefore the building spaces meeting the criteria for un-conditioned space.

As per the ASHRAE 90.1-2007 Users Manual, unconditioned space is not cooled and has a heating system smaller than 3.4 BtuA unit of energy consumed by or delivered to a building. A Btu is an acronym for British thermal unit and is defined as the amount of energy required to increase the temperature of 1 pound of water by 1 degree Fahrenheit, at normal atmospheric pressure. Energy consumption is expressed in Btu to allow for consumption comparisons among fuels that are measured in different units./h#sq.ft. Note that for unconditioned spaces, the envelop does not necessarily need to be modeled, but the electric loads from the lighting and fans shall be included in the energy calculations per 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. 2028 dated 1/29/2008.

I don´t know if they´re telling us not to model any HVAC systems or that we have to install one if we dont comply with the criteria.

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Marcus Sheffer LEED Fellow, 7group Oct 21 2013 LEEDuser Expert 41683 Thumbs Up

If the space is unconditioned (i.e. meets the definition they state) you do not have to model heating or cooling equipmentThe equipment used for cooling room air in a building for human comfort.. It is only if you have one or the other that you need to model the one you do not have.

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JOHANNA SENOTT Architect / Environmental adviser, EA Energia y Arquitectura Oct 22 2013 LEEDuser Member 651 Thumbs Up

The spaces in the model have a range of 30-50 BtuA unit of energy consumed by or delivered to a building. A Btu is an acronym for British thermal unit and is defined as the amount of energy required to increase the temperature of 1 pound of water by 1 degree Fahrenheit, at normal atmospheric pressure. Energy consumption is expressed in Btu to allow for consumption comparisons among fuels that are measured in different units./hsf does this means I have to model both heating and cooling in my model or do I have to install the equipment physically in the building and model it?

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Marcus Sheffer LEED Fellow, 7group Oct 23 2013 LEEDuser Expert 41683 Thumbs Up

The 3.4 refers to the heating system capacity. Since you have no heating system your capacity is less than 3.4 and you do not need to model heating or cooling. Your space is unconditioned.

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JOHANNA SENOTT Architect / Environmental adviser, EA Energia y Arquitectura Oct 23 2013 LEEDuser Member 651 Thumbs Up

Thanks a lot Marcus you´ve been really helpful..

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HOUCINE TLEMSANI Mechanical Designer MEP Engineering Solutions, Inc
Oct 18 2013
LEEDuser Member
296 Thumbs Up

Fan power credit and packaged vav

I am working on a project where the base line system is a packaged 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 reheat.
ASHRAE 90.1 specify the packaged efficiency as 9.8 EER including the compressor heat rejection and fans. The question I am having is that if we are taking credit for the fan power pressure drops adjustment in the system in accordance with ASHRAE 90.1 are we allowed to change the packaged efficiency by including the fan credit allowance or no?

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Marcus Sheffer LEED Fellow, 7group Oct 18 2013 LEEDuser Expert 41683 Thumbs Up

It depends on your modeling software. Most of them separate the fan power automatically and you enter the EER as indicated in Table 6.8.1A without making the adjustment yourself.

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HOUCINE TLEMSANI Mechanical Designer, MEP Engineering Solutions, Inc Oct 25 2013 LEEDuser Member 296 Thumbs Up

thank's Marcus
the trace 700 software does automatically separate the different components of the plant when packaged EER is used but will not add the fan power associated with the pressure drop credit to the total plant.
OK assuming a 50 ton plant with a 9.8 EER the total plant allowed power is 61.22 KW. the energy break out of the plant 5 kw heat rejection. 25 KW compressor and 20 KW fan that is just assumptions.
90.1 pressure drop credit is allowing an extra 5 KW energy to be applied to the fan making the total power of the plant increase to 66.22 KW. resulting in an EER 9.646
is that correct or do you see any problem.

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Marcus Sheffer LEED Fellow, 7group Nov 01 2013 LEEDuser Expert 41683 Thumbs Up

Yes we do.

The total plant power should not be increasing. If the fan power increases due to the pressure drop adjustment, the heat rejection and compressor power would be reduced to accommodate the extra supply fan power. You are separating the fans from the rest of the plant so you don't adjust the EER. You reduce the total by subtracting out the fan power.

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Curtis Clark Director of Sustainability Services GSBS Architects
Oct 18 2013
LEEDuser Member
80 Thumbs Up

ASHRAE STANDARDS 90.1 Appendix G - Humidity Controls

Appendix G does not address humidity controls. Is it correct to assume that if you have humidity controls in the proposed building, you must put the same humidity controls in the baseline building, regardless of the requirements of ASHRAE Standard 55?

For example, if a building owner requires a minimum 40% humidity, you must model humidity controls with minimum of 40% in both baseline and proposed buildings.

For example in Salt Lake City, it has very dry summers. Most building owners do not require 30% humidity minimum as per ASHRAE Standard 55. You do not install humidity control in the baseline and proposed buildings.

Please send your comments.

Curtis J Clark

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Marcus Sheffer LEED Fellow, 7group Oct 18 2013 LEEDuser Expert 41683 Thumbs Up

If you have a humidifier in the proposed case you model the same in the baseline and treat it as a process load. If you do not have a humidifier in the proposed you do not model one in the baseline.

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David Mirabile LEED AP, BD+C
Oct 17 2013
Guest
873 Thumbs Up

Domestic Water Heating

I am modeling a school in which we are using several water-to-water geothermal heat pumps for our domestic water heating. I am assuming I should be able to get significant energy savings in comparison to a standard electric water heater. How do I model this between my baseline and proposed? Can't I use the ASHRAE minimum required efficiencies for an electric water heater based on the BTUH's needed and compare the energy usage to my W2W Heat pumps? My LEED reviewer did not like this approach the first time around. Thanks!

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Marcus Sheffer LEED Fellow, 7group Oct 17 2013 LEEDuser Expert 41683 Thumbs Up

Table G3.1-11 Baseline (b) indicates your baseline should be electric resistance. See Table 7.8 to determine the efficiency of the baseline system. Not sure what your reviewer saw?

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David Mirabile LEED AP, BD+C Oct 18 2013 Guest 873 Thumbs Up

The reviewer comment was essentially "Provide additional information to justify all water heater savings" and then described a method for low-flow credit of which I was not attempting.

With the volume of a water to water 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. being minimal, what can I compare my efficiencies to between the baseline and proposed? So if I have roughly 20 gal of Volume between all my heat pumps, I am looking at about a 90% EF requirement? And my savings would be any efficiency above that 90% that my W2W heat pumps are actually producing? Maybe I am just not understanding the process and comparing the incorrect systems, can you enlighten me?

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Marcus Sheffer LEED Fellow, 7group Oct 18 2013 LEEDuser Expert 41683 Thumbs Up

Sounds like you are comparing the right systems.

So your service water heating savings are basically all related to the efficiency difference of the systems correct? If so the percent energy savings you are claiming should be roughly proportional to the percent difference in efficiency. If these values are in alignment then just explain that to the reviewer. If not then check your modeling inputs for any potential issues.

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David Mirabile LEED AP, BD+C Oct 18 2013 Guest 873 Thumbs Up

That is correct, or at least that was my intent, to base my savings on the efficiency differences. But the efficiency differences have to both be based on a 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. correct? I cannot use an electric 20 gal water heater versus my heat pump? I know the focus of the energy savings is on the HVAC side, but it seems like LEED is not giving the savings on the SHW side its due. Outside of figuring in the low flow fixtures, is there any other approach to increase savings on the SWH side? Thanks for all you help and insight.

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Marcus Sheffer LEED Fellow, 7group Oct 18 2013 LEEDuser Expert 41683 Thumbs Up

See my first comment. Your baseline is clearly electric resistance IMO. Even the "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." listed in table 7.8 uses the same formula as the electric resistance water heater so there should be no difference.

Demand reduction is a very common way to show additional hot water savings. Other strategies (extra tank and pipe insulation, heat traps, etc.) tend to produce very minor additional savings.

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David Mirabile LEED AP, BD+C Oct 18 2013 Guest 873 Thumbs Up

But that doesn't allow me to model a Volume difference in the baseline, based on a typical storage tank achieving the same capacities as my proposed, does it? (Thus lowering the efficiency requirement of my baseline and greatly increasing my savings).

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Marcus Sheffer LEED Fellow, 7group Oct 18 2013 LEEDuser Expert 41683 Thumbs Up

I am not understanding why you would have a significant volume difference. I would think that the w-to-w heat pumps would have the need for storage since their recovery would be slower? It would not be a fair comparison to compare your system with a 20 gallon electric water heater if that single heater could not meet the hot water demand. Is there storage associated with the heat pumps? If so the volume of the storage would be used for comparison in the baseline.

You size the baseline system based on 7.4.1 which indicates you size it based on the hot water demand as calculated for the proposed design. If this results in different storage volumes in both cases then you could attempt to justify a difference based on the storage needs in both cases. I think you would need to demonstrate why there is a difference.

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David Mirabile LEED AP, BD+C Oct 23 2013 Guest 873 Thumbs Up

OK, I had to investigate this by going to the engineer of design. So for my proposed, I have a 147.7 mbh output capacity on my W2W 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. with an input of 7.148 kW and COP of 6.1. This uses a 318 gallon storage tank. Therefore, using 0.93-0.00132V for my req'd minimum efficiency, EF= 0.51. Then I can model against a baseline water heater of COP=0.51?

So,
COP=out/input

0.51=147,700 btuh / 3413 * kW,

or

147,700 btuh / 0.51 * 3413 = kW

84.9=kW

I therefore am supplying the same amount of HW capacity using (84.9kW-7.148kW) 77.8kW less energy?

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Marcus Sheffer LEED Fellow, 7group Oct 24 2013 LEEDuser Expert 41683 Thumbs Up

The size category in Table 7.8 is based on the baseline system capacity as calculated to meet the proposed hot water demand. It is not based on the proposed input 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. capacity. In your case it appears highly likely the the baseline size category will be over 12 kW. So you use the stand-by loss formula and assume the electric coil in the tank has a COP of 1.

Regarding your calculations above - the EF includes stand-by losses so it is not the same thing as COP. As a result the rest of your calculations are not valid.

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David Mirabile LEED AP, BD+C Oct 28 2013 Guest 873 Thumbs Up

Im sorry, I am still confused. With a proposed hot water demand of 147.7mbh being provided with a proposed 7.148kW w2w 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. at COP=6.1 with a proposed 318 gal storage tank, not sure what that gets me when using the SL formula. A SL=644 btuh? What does that tell me in comparing baseline and proposed savings.

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Marcus Sheffer LEED Fellow, 7group Oct 28 2013 LEEDuser Expert 41683 Thumbs Up

Use the proposed demand to size an electric storage tank hot water system for the baseline. What size electric element is needed to meet the proposed demand? The storage tank size is identical to the proposed. That value you calculated is the stand-by loss of the storage for the baseline system. The COP is 1. These are the inputs you need to model the baseline system to determine the savings.

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Ivan Souza Sustainability Consultancy Services Cushman & Wakefield
Oct 17 2013
LEEDuser Member
842 Thumbs Up

Energy Savings - Solar Water Heating

Hi!

when i have a solar water heating system, must submit like energy savings?

Thanks

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Marcus Sheffer LEED Fellow, 7group Oct 17 2013 LEEDuser Expert 41683 Thumbs Up

The energy savings would be submitted under Section 1.8 of the form. It is usually a good idea to submit the calculations or at least an explanation of how the renewable energy use was calculated.

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Pedro Ribeiro Director of Sustainability Edifícios Saudáveis Consultores
Oct 17 2013
LEEDuser Member
676 Thumbs Up

Minimum equipment efficiencies ASHRAE 90.1

Can anyone please clarify if packaged air-to-water heat pumps (chilled and/or hot water production) have to:
1) comply with minimum efficiency requirements set to for water chilling packages in cooling mode?
2) which, if any, minimum efficiency requirements have to be complied with in heating mode (hot water production)?

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Marcus Sheffer LEED Fellow, 7group Oct 17 2013 LEEDuser Expert 41683 Thumbs Up

I believe that those systems are not covered by 90.1 and are therefore exempt from any minimum efficiency requirements.

I am not sure if they are covered by 90.1-2013 which just came out.

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