CS-2009 EAp2: Minimum Energy Performance

  • 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.

  • 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. 


  • 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. 

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 and CS Appendix 2: Energy Modeling Guidelines. 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.


  • Core and Shell projects must mandate the requirements for the tenant spaces within a tenant guideline document such as one developed for SSc9: Tenant Design and Construction Guidelines. 


  • 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. 


  • 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. 


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

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 Core and Shell Development

    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.

    OR

    Option 4. Brazil compliance path: PBE Edifica

    Projects in Brazil that are certified at the “A” level under the Regulation for Energy Efficiency Labeling (PBE Edifica) program for all attributes (Envelope, Lighting, HVAC) achieve this prerequisite. The following building types cannot achieve this prerequisite using this option: Healthcare, Data Centers, Manufacturing Facilities, Warehouses, and Laboratories.

    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.

    Pilot ACPs Available

    The following pilot alternative compliance path is available for this prerequisite. See the pilot credit library for more information.

    EApc95: Alternative Energy Performance Metric ACP

    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

New York State Energy Research and Development Authority (NYSERDA)

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


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.


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.


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: CS-2009 EA

Sample LEED Online forms for all rating systems and versions are available on the USGBC website.

Design Submittal

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

1017 Comments

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Mathilda Jonsson Environmental Certification Engineer (LEED AP BD+C) Skanska
Jan 26 2016
LEEDuser Member
1061 Thumbs Up

Energy model for a version 4 project in a version 2009 project

Project Location: Sweden

Hi all!
We started up a LEED for CS version 4 project and got really good results for the energy model. The owner wants to double certify the building so it also will earn LEED for CS version 2009 certification. Would it be possible to use the v.4 energy model to the v. 2009 certification? It's more stringent so I imagine it would be fine.
Thanks!

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Marcus Sheffer LEED Fellow, 7group Jan 26 2016 LEEDuser Expert 57013 Thumbs Up

Yes you can. There is a revised point scale you can use.

http://www.usgbc.org/resources/ashrae-901-2010-adjusted-point-scale-leed...

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Nicolas Martinez Ochoa
Jan 14 2016
Guest

Heating System G3.1.10 ( c )

Project Location: Colombia

Hello,
I’m working on a Core & Shell office building in Bogota and the baseline system is 8. The building has a central cooling system with chillers and air handle units in each floor, it doesn’t have a heating system. According to the G3.1.10 (c) table of ASHRAE 90.1, the proposed model must have a heating system equal to the baseline, ie electrical resistance and parallel fan-powered boxes (PFP). I don’t want to model PFP boxes in the proposed model due to the fan power consumption. I don’t want neither to model a lower heating temperature setpoint because the fan in the PFP box would be working all the time.
To meet the baseline heating system, Can I use only an electric resistance in the air handle unit or placing a simple reheater in the zone enough? Or is necessary to model PFP boxes with a heating coil in each zone?
Thank you.

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Marcus Sheffer LEED Fellow, 7group Jan 17 2016 LEEDuser Expert 57013 Thumbs Up

If you follow this path you have to model the proposed identical to the baseline. You can't choose to model it a different way that would be to your advantage.

Personally I would just explain to the reviewer that you have not modeled a heating system while demonstrating that a heating system would not result in any heating energy use. If you can do that as a reviewer I would be OK with you not modeling a heating system as it represents a more accurate prediction of future energy use.

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Nicolas Martinez Ochoa Jan 19 2016 Guest

Thank you Marcus.
In system 8, heating system for the baseline uses an electric resistance. My question is, Can I model the heating system using only an electric resistance in the AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork.?, Or the only way for modeling the heating system is including a PFP box with reheat?.
Thanks.

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Marcus Sheffer LEED Fellow, 7group Jan 20 2016 LEEDuser Expert 57013 Thumbs Up

You have to model it in the box with reheat.

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Andy Fouss
Jan 08 2016
Guest

Energy Recovery (G3.1.2.10)

The proposed building is a dormitory served using individual fan coils (with no outside air in the fan coils) and the outside air for the building being supplied by a single dedicated outside air unit. The dedicated outside air unit is over 5000 cfm and is 100% outside air. In the proposed building, the dedicated outside air unit has a heat recovery wheel.

The baseline building is required to be a type 2 system (PTAC with gas boiler heat). There are not any individual spaces that require 5000 cfm or over 70% outside air.

Is the baseline building required to be modeled with energy recovery because my proposed dedicated outside air unit meets the requirements of G3.1.2.10 (since we choose to group all the exhaust together to recover the energy)? Or can the baseline building be modeled without energy recovery?

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Marcus Sheffer LEED Fellow, 7group Jan 11 2016 LEEDuser Expert 57013 Thumbs Up

Energy recovery in any proposed system does not affect whether energy recovery is in a baseline system.

So the first question - No.

Second - Yes without energy recovery as far as I can tell.

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Samuel Sura Mr e-Dome
Jan 08 2016
LEEDuser Member
35 Thumbs Up

Baseline systems

Hi LeedUsers,

I have one simple question. According to section G3.1.1 of ASHRAE 90.1 Standard each floor for system 5 through 8 shall be modeled with a separate HVAC system. I hope it doesnt mean that each floor shall have its own heating and cooling source but only AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. per floor and these AHUs will be supplied by one central heating/cooling source (or more central sources according to section G3.1.3).

I definitely prefer the second option but I rather ask.

Thank you in advance.

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Marcus Sheffer LEED Fellow, 7group Jan 08 2016 LEEDuser Expert 57013 Thumbs Up

For a system 5 and 7 the heating is a centralized boiler system. For system 5 and 6 each system has DX cooling. For system 7 it is also centralized cooling which is also the case for system 8. So whether the heating and cooling source is central or within each system varies depending on the system in question.

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Samuel Sura Mr, e-Dome Jan 11 2016 LEEDuser Member 35 Thumbs Up

Thank you Marcus for your help.

I would like to ask another one question:
I have office building where 30 000 m2 (cca 323 000 ft2) is office space (system 7) and almost 15 000 m2 (cca 161 500 ft2) is for parking, what system type I should choose for the garage? Should I follow section G3.1.1b and choose system 3 because of significant difference in occupancy and process loads? And then eliminate heating and cooling loads for garage HVAC system by setting up an unachievable 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.... Could it be like that?

Thanks!

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Marcus Sheffer LEED Fellow, 7group Jan 11 2016 LEEDuser Expert 57013 Thumbs Up

Sounds like the parking garage is unconditioned (no heated or cooled)? If so you don't model any system in either model.

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Samuel Sura Mr, e-Dome Jan 12 2016 LEEDuser Member 35 Thumbs Up

Yes that's right, it is unconditioned space of course, but it is underground garage and there are several extract fans for removal of exhaust gases. So I thought that it is necessary to model every end-use load components as stated in Table G3.1.1a. Therefore I was looking for solution how to model energy consumption for parking garage fans in baseline building.

Please correct me if I'm wrong but I thought if proposed building has any energy consumption so the baseline has to have too.

Thank you.

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Marcus Sheffer LEED Fellow, 7group Jan 12 2016 LEEDuser Expert 57013 Thumbs Up

That table only applies to conditioned spaces.

The exhaust fans in the garage are process loads and would be modeled identically in both models. You can claim savings for demand controlled ventilation based on CO as an exceptional calculation if this strategy is not required or common practice in your location.

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Samuel Sura Mr, e-Dome Jan 13 2016 LEEDuser Member 35 Thumbs Up

Thank you Marcus, I appreciate your help.

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Michael Wahjudi ESD Consultant Kaer Pte Ltd
Dec 10 2015
Guest
44 Thumbs Up

LEED CS building with very minimum landlord provision

Project Location: Singapore

Hi all, I have LEED CS with very minimum client provision without AC systems (only emergency lights, emergency fans and lifts). But the main tenant has been agreed from the building and the entire building is tenanted to this tenant only. My question is:
1. Should we model the energy modelling based on only client provision or we can include the tenant provision, since it is agreed from the beginning of this project and we have tenant energy systems data? Since landlord provision is very minimum.
2. Are we allowed to include tenant energy system data for LEED CS project?
3. Any official documents indicate the answer for my question 1 and 2? (eg. MPR, Reference guide etc)

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Marcus Sheffer LEED Fellow, 7group Dec 11 2015 LEEDuser Expert 57013 Thumbs Up

1. Yes you can model the tenant design and claim energy savings associated with it.
2. yes
3. Not sure I would have to go digging. Start with the Reference Guide.

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Michael Wahjudi ESD Consultant, Kaer Pte Ltd Dec 13 2015 Guest 44 Thumbs Up

Thanks Marcus for your opinions. I still have something in mind.
1. If we can exclude the tenant design, how we show the improvement from ASHRAE 90.1? Since the building energy consumption will be extremely very low due to minimum provision of energy related system from the developer.
2. I've noticed as well based on ID #2084, it seems like even we don't have HVAC and lighting design from tenant. We should model HVAC and lighting according to ASHRAE 90.1. Am I correct?
3. If we should model HVAC and lighting design, should we include some assumptions on the potential tenant’s future provision, eg. Chiller plant, air-distribution system, interior lightings, plug loads, etc? or we can follow certain guideline for the HVAC sizing?

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Marcus Sheffer LEED Fellow, 7group Dec 14 2015 LEEDuser Expert 57013 Thumbs Up

1. CS projects must include all energy use in the core areas shared by tenants and due to the influence of the building shellThe exterior walls, roof, and lowest floor of a building, which serve to separate and protect the interior from the elements (precipitation, sunlight, wind, temperature variations).. In most areas the building shell influences heating and cooling energy use so this is included and any envelop improvements can be used to show savings. If the CS scope is extremely minimal as it impacts energy savings then it does get much harder to meet the minimum energy savings.
2. Yes if there is no tenant design or provisions in the tenant lease agreements, then the tenant spaces are modeled identical to the baseline.
3. If you are modeling a design then you model that design. There should be no assumptions regarding HVAC or lighting and the HVAC should be modeled using the capacities in the design, not following some guideline.

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Michael Wahjudi ESD Consultant, Kaer Pte Ltd Dec 15 2015 Guest 44 Thumbs Up

Great. Thanks Marcus for your sharing. Appreciate that

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Agata Mozer GO4IT SP Z OO SP K
Dec 08 2015
LEEDuser Member
402 Thumbs Up

ASHRAE requirements for cooling towers

Project Location: Poland

As part of this Prerequisite we have to provide cooling towers that comply with requirements of section 6.4 of 90.1-2007 ASHRAE Standard. In Table 6.8.1G there are performance requirements listed but only for standard rating conditions (for entering water temperature of 35C and leaving water temperature 29C). What if the proposed by the designers cooling tower has other water parameters? What are the performance requirements for cooling towers with water of higher temperature?

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Marcus Sheffer LEED Fellow, 7group Dec 11 2015 LEEDuser Expert 57013 Thumbs Up

The standard rating conditions are the parameters used to determine the minimum efficiency rating (like 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. being tested at certain temperatures). If your design situation does not match this it does not matter, the equyipment must meet the minimum efficiency at the rated conditions. The minimum performance requirements would still apply to your situation.

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Ciaran McCabe
Dec 07 2015
LEEDuser Member
36 Thumbs Up

HVAC system for 5 storey office block.

I am modeling a core and shell building with 5 floors. This building will be served by two air handling units. Is there any requirement for me to set up a different HVAC system (a copy) for each floor of can I just go with the two which is the proposed.

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Marcus Sheffer LEED Fellow, 7group Dec 07 2015 LEEDuser Expert 57013 Thumbs Up

See G3.1.1 which requires a system per floor for systems 5 to 8.

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Pedro Urazan
Dec 04 2015
Guest

Eficiency of Electric motors operated with VFD

Project Location: Colombia

I would like to know if electric motors that are going to be operated by a VFDA variable frequency drive (VFD) is a device for for controlling the speed of a motor by controlling the frequency of the electrical power supplied to it. VFDs may be used to improve the efficiency of mechanical systems as well as comfort, because they use only as much power as needed, and can be adjusted continuously. (Variable Frequency Drive), need to comply with the eficiency requirements of the ASHRAE 90.1 table 10.8.

Thanks

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Marcus Sheffer LEED Fellow, 7group Dec 04 2015 LEEDuser Expert 57013 Thumbs Up

Yes

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Ciaran McCabe
Dec 04 2015
LEEDuser Member
36 Thumbs Up

Building Area Method Vs Space by Space Method

In terms of the Energy Model for Core & Shell is the "Building Area Method" more applicable as the final layout has not been decide yet ?

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Marcus Sheffer LEED Fellow, 7group Dec 04 2015 LEEDuser Expert 57013 Thumbs Up

Either method could still be used.

The proposed tenant spaces should be modeled identically to the baseline or according to the requirements of tenant lease agreement if attempting to claim energy savings.

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Ciaran McCabe
Dec 03 2015
LEEDuser Member
36 Thumbs Up

ASHRAE 90.1 PRM Energy Model

Hi,

Does anyone know a good step by step guide useful when working on the 90.1 PRM appendix G model ? To make sure all boxes are ticked !

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Marcus Sheffer LEED Fellow, 7group Dec 03 2015 LEEDuser Expert 57013 Thumbs Up

The section 1.4 tables used to document LEED serve a dual purpose. They are intended to both provide guidance toward the accurate creation of the Baseline model and to summarize the modeling inputs for the reviewer. If you carefully follow the tables reading the notes and the pop up comments you should also accurately create the Baseline model.

http://www.usgbc.org/resources/eap2-section-14-tables-new-all-bdampc-pro...

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Ciaran McCabe Dec 04 2015 LEEDuser Member 36 Thumbs Up

Thanks.

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Scott McMillan
Nov 19 2015
LEEDuser Member
79 Thumbs Up

Parking Garage Demand Controlled Ventilation

Project Location: Indonesia

Hi there,

When a proposed building model includes parking garage DCV based on CO - How should the control of the baseline model garage fan volume be controlled?. Should the baseline model also control ventilation based on CO level or can it be at a fixed volume? ASHRAE 90.1 doesn't seem to describe control methodology or schedules for parking garages which is surprising given how significant the energy consumption can be.

We have submitted preliminary design stage documentation and had provided an exceptional calculation with fixed flowrate control for the baseline model and the proposed based on CO. We received the following comment back from the assessor:

"The Baseline case description should provide evidence that garage demand control ventilation is not standard practice for similar newly constructed facilities (three facilities built within the past five years of the project registration date) where the project is located"

Where does this requirement come from? - it's certainly not in ASHRAE 90.1. Why is DCV for parking garage extract so special that it needs to be demonstrated it's not common practice at the site location - we don't need to do this for any other energy conservation measures?

The prerequisite criteria is based on demonstrating a percentage improvement compared to ASHRAE 90.1-2007 - not compared to what is typical practice at the site location...

I would have thought LEED would be promoting DCV rather than making it more difficult to achieve credit for doing the right thing.
Cheers

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Marcus Sheffer LEED Fellow, 7group Nov 20 2015 LEEDuser Expert 57013 Thumbs Up

The reason this is treated this way is that some codes in some areas require this strategy. This is a process load (90.1-2007 does not regulate it) and savings must be claimed via an exceptional calculation. The baseline for an exceptional calculation is always related to standard industry practice in that particular location. You don't do it for may other strategies because 90.1-2007 gives us the baseline, in this case it does not.

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Scott McMillan Nov 22 2015 LEEDuser Member 79 Thumbs Up

Thanks Marcus,

Slightly confused however, as the LEED 2009 credit language includes parking garage ventilation as regulated (non-process) energy in the list of examples:

"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"

So if its considered non-process (in LEED 2009 anyway) we shouldn't be required to demonstrate that DCV is not common practice.

Worth a try arguing that do you think?

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Marcus Sheffer LEED Fellow, 7group Nov 23 2015 LEEDuser Expert 57013 Thumbs Up

I see your confusion. However, I don't think you have a leg to stand on when arguing this. 90.1 does not regulate parking garage ventilation despite the incorrect language, so there is no defined baseline. USGBC/GBCI has defined the baseline as as varying depending on local requirements. 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. 10371 addresses this issue.

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Giusy Amorusi INTERTECNO S.p.A.
Nov 06 2015
LEEDuser Member
34 Thumbs Up

System Fan Power for System 8 VAV with PFP boxes

Project Location: Italy

Hi everyone,
I have to model system fan power in 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 in accordance with Table G3.1.2.9 ASHRAE 90.1 2007.
I calculate the system fan power with value of supply air (value calculated by software). Is this the sum of the supply fan, the return fan and the exaust fan powers? If I calculate the supply fan power in this manner, the return fan power as indicated in G3.1.2.8 (with 90% of the supply fan air quantity) and the exhaust fan power based on the exhaust air, when I fill these values in Table 1.4, the allowed fan power is just nearly half of the sum.
I have also considered the Pressure Drop Adjustments.
I have doubts about the fan calculations, because I use the same formula for three calculations.

Could you help me?
Thanks a lot.

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Marcus Sheffer LEED Fellow, 7group Nov 06 2015 LEEDuser Expert 57013 Thumbs Up

The fan power calculation for the baseline includes the supply, return and exhaust fans. You can then divide this total among the various fans in the system. This is usually done in proportion to the proposed system if applicable.

Only do the calculation once.

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Giusy Amorusi INTERTECNO S.p.A. Nov 06 2015 LEEDuser Member 34 Thumbs Up

Thank you so much Marcus!

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Yasuhito Koike LEED AP, Green Building Consultant Izumi System Planning
Oct 23 2015
LEEDuser Member
103 Thumbs Up

ACP Revised Points Thresholds

Project Location: Japan

We have a C&S project and are planning the energy simulation for EAp2 and EAc1. I think we can use ACP revised points thresholds for our project, but would like to make sure if there are any restriction to use it. The only official source I could find was the excel file named "CS 2009 EAp2-c1 ACP.February 2014.xls".
Is there any other information I didn't see?
Thank you in advance.

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Marcus Sheffer LEED Fellow, 7group Oct 26 2015 LEEDuser Expert 57013 Thumbs Up

There are no restrictions I am aware of. The document stands alone so I don't think you missed anything.

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Yasuhito Koike LEED AP, Green Building Consultant, Izumi System Planning Oct 26 2015 LEEDuser Member 103 Thumbs Up

Thank you Marcus.

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Mary Kay Gonzalez
Oct 21 2015
Guest

Default Tenant Receptacle Loads

Project Location: United States

On a C&S healthcare building, we simulated the receptacle load based on CS Appendix 2, Table 1, as the appendix directed. The reviewer commented that the value of 1.5w/sf was higher than the 1w/sf default value per the ASHRAE 90.1-2007 User's Manual, and asked for documentation to confirm the predicted future use.

Will a narrative response citing our source for the default value generally satisfy the documentation?

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Marcus Sheffer LEED Fellow, 7group Oct 22 2015 LEEDuser Expert 57013 Thumbs Up

Yes it should. Either value should be acceptable.

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Giusy Amorusi INTERTECNO S.p.A.
Oct 20 2015
LEEDuser Member
34 Thumbs Up

Equipment Capacities

Project Location: Italy

I am working on simulation with Carrier's HAP. I have to model baseline 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 PFB boxes) in accordance to ASHRAE 90.1 Appendix G 2007. As heating type I should use Electrical resistance. I would know if electrical resistance means electrical coils on field or hot water with electrical boiler.
I have this doubt because I'm not able to model the 25% oversizing for heating, when I use the elctrical resistance on field (ref. G.3.1.2.2).
Could you help me?

Thank you.

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Marcus Sheffer LEED Fellow, 7group Oct 20 2015 LEEDuser Expert 57013 Thumbs Up

It should be electric coils and not a boiler.

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Giusy Amorusi INTERTECNO S.p.A. Oct 20 2015 LEEDuser Member 34 Thumbs Up

Thanks.
You are confirming my opinion, but I have the problem how to oversize by 25% the heating coils in Carrier's HAP software. Do you have any references about this?
Thanks for your help.

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Marcus Sheffer LEED Fellow, 7group Oct 20 2015 LEEDuser Expert 57013 Thumbs Up

The electric resistance is modeled as reheat at the zone level.

In HAP you can add an over-sizing factor at the system level. I am not sure if that translates down to the zone level or not. You can also add a safety factor but you should not do both. The specifics of exactly how to do this is HAP should be addressed to customer service or you can post a specific question to the HAP users group available through onebuilding.org.

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Gwen Sheinfeld Director, Corporate Sustainability Healthy Buildings
Sep 04 2015
LEEDuser Member
133 Thumbs Up

ASHRAE AEDG Retail - Prescriptive skylight requirement

Project Location: United States

We are working on a small retail store 18,000 sqft and we are considering pursuing the prescriptive compliance path AEDG (option 2) to meet EAp2. We fall under zone four which has a 3% skylight recommendation.
Our current design does not include any skylights, are we required to include skylights in our design to meet the prerequisite?

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Christopher Schaffner Principal & Founder, The Green Engineer, Inc. Sep 04 2015 LEEDuser Expert 8389 Thumbs Up

The Table shows a 3% maximum. Skylights are not required.

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Muge Karasahin LEED AP BD+C, Architect ALAN Mimarlik ve Proje Yonetimi
Aug 29 2015
LEEDuser Member
8 Thumbs Up

Historical Landmark

We have a large scale international project in the eastern Europe. Exterior light design LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. rates cannot comply with ASHRAE 90.1-2007, Section 9 – Lighting_Mandatory 9.4-table 9.4.5 non-tradable surfaces. Therefore we are trying to go for Exceptions statement of Section 9.4.5: Lighting used to highlight features of public monuments and registered historic landmark structures or buildings.

We are informed that the Local Authorities should register the city as a historical landmark in order to benefit from the exceptions statements. The building is a nominee for being a landmark because of its historic location, supertall structure and importance to the city.

Could you please advise us on how we can prove to GBCI that this building is a landmark?

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Marcus Sheffer LEED Fellow, 7group Aug 31 2015 LEEDuser Expert 57013 Thumbs Up

It must be a historic landmark. Very few if any new buildings would considered a historic landmark. To qualify it must be registered by a governmental agency as a historic landmark.

So whoever designed the lighting or whoever is demanding that there be more than allowed lighting needs to get on board with a green building. See not exceptions, seek solutions that help the environment.

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Agata Mozer GO4IT SP Z OO SP K
Aug 11 2015
LEEDuser Member
402 Thumbs Up

pressure drop adjustemnt in the baseline model

Project Location: Poland

I have two questiones:
1. Pressure drop adjustment for heat recovery in the baseline fan power calculations can be taken only if the heat recovery is modeled in the baseline case regardless of the fact that it's present in the proposed case, is that correct?
2. There is a new excel file with Table 1.4 available. In one of the sheets we should list all HVAC systems modeled in the proposed and baseline case. Should we list there also the systems that serve only as exhaust (only exhaust fans with no heating nor cooling).

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Marcus Sheffer LEED Fellow, 7group Aug 31 2015 LEEDuser Expert 57013 Thumbs Up

1. Correct.
2. Exhaust fans serving unconditioned spaces are considered process and should be entered in the equipment tab in the spreadsheets.

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Samuel Sura Mr e-Dome
Jul 21 2015
LEEDuser Member
35 Thumbs Up

no cooling / using addendums

Hello,

I have two questions:

1) we are working on residential building where its 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. has heating and cooling, but rooms situated on north facade has no cooling system. Whole building floor area is 5 600 m2 (60 277 ft2) and these rooms without cooling are only 340 m2 (3 660 ft2). My question is how I should model the proposed HVAC system regarding to Table G3.1.10d where is stated: "where no cooling system exist or ......., the cooling system shall be identical to the system modeled in the baseline building design." I think this is definitely not my case, I think this can be applied where whole building has no cooling system. But can I leave these rooms without any cooling and in baseline building the cooling system will be present?

2) It is not clear to me if I have to use addendums to ASHRAE Standards or not. Or just some addendums?

I am sorry for maybe dumb questions but I rather ask than stay in confusion.

Thank you in advance.

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Marcus Sheffer LEED Fellow, 7group Jul 21 2015 LEEDuser Expert 57013 Thumbs Up

Technically you are required to model cooling the both cases in the whole building. You are however allowed to model a high temperature set point in the spaces without cooling so that they system never operates. What we do is tell the reviewer that we could model a cooling system where it does not exist and set the temperatures high enough for it not to operate but have not done so because it is a waste of time. We then just model the proposed as designed and model the corresponding areas in the baseline without any cooling, just as in the proposed.

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Samuel Sura Mr, e-Dome Jul 21 2015 LEEDuser Member 35 Thumbs Up

Thank you very much Marcus for quick reply. I like your way how to deal with it.

And what about my second question, because now I dont know if using Addendums is required or I should forget about all Add. and just work with "first edition" of Standard 90.1-2007 and issued Erratas. Because Addendum r completely changes Appendix G or Addendum g changes some U factors etc. So I dont know...

Thanks

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Marcus Sheffer LEED Fellow, 7group Jul 21 2015 LEEDuser Expert 57013 Thumbs Up

You are not required to use any of the addenda. You should only use an addenda if you need to do so. Some of them are very helpful depending upon the issues in your models. Keep in mind that if you use an addendum you must use it in its entirety.

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Samuel Sura Mr, e-Dome Jul 21 2015 LEEDuser Member 35 Thumbs Up

OK, now I understand. Thank you Marcus!

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Tommy Linstroth Principal Trident Sustainability Group
Jul 02 2015
LEEDuser Member
480 Thumbs Up

Historic Building Cold Dark Shell

We're working on a historic renovation, total gut, but will be left as a cold dark shell - no MEP at all, it will all be in the tenant scope of work. The building is small, around 8,000 sf, and the team will be gutting it, replacing the windows, and likely insulating the roof. What do we need to do to document compliance with the pre-req? Do we need to model it and show that our envelope improvements exceed ASHRAE? Can you apply the ASHRAE design guidelines just to what's in our scope? If so, do the rest of the guidelines have to be in the lease agreement? Thanks!

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Marcus Sheffer LEED Fellow, 7group Jul 03 2015 LEEDuser Expert 57013 Thumbs Up

Under Option 1 you need to show the minimum savings. Since you are making envelop improvements you can claim those savings. Any tenant related savings would need to be from requirements in the lease agreement.

Under Option 2 all you need to do is meet the AEDG requirements for the scope of work. In this case just the envelop. The rest of guidelines do not have to be in the lease agreement. You will earn the prerequisite and one EAc1 point.

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Annalise Reichert LEED Project Coordinator, Environmental Building Strategies Oct 21 2015 LEEDuser Member 231 Thumbs Up

I am working on a very similar project. It's a small historic building with no MEP in the Core and Shell scope and minor envelope upgrades. How should the team document IEQp1 Minimum Ventilation Requirements, if the mechanical ventilation system is part of the TI scope? Can we simply include ventilation requirements in the Tenant Guidelines?

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Marcus Sheffer LEED Fellow, 7group Oct 21 2015 LEEDuser Expert 57013 Thumbs Up

I would think that they need to be in the lease agreement.

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Tommy Linstroth Principal, Trident Sustainability Group Oct 21 2015 LEEDuser Member 480 Thumbs Up

We've done that through the lease agreement in the past, and are doing so again in this case. I have a pre-review call in 3 weeks and will be confirming that and will let you know!

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Felipe Duran
Jul 01 2015
LEEDuser Member
372 Thumbs Up

Additional lighting power density in a retail store

Project Location: Chile

Dear All,

We are working on a shopping mall project which is pursuing LEED for C&S certification. According to table 9.6.1, maximum lighting power density for retail store is 18 W/sqm plus accent lighting. Since we don´t know which type of sales area is going to use the retail store, can we model the lighting power density considering "Sales Area Type 3" allowance according to table 9.6.2.? We would like to consider 44 W/sqm (Retail Sales Area 18 W/sqm + 26 W/sqm). Such lighting power density is close of what will be available for the tenants for interior lighting. Since there is not lighting design for tenant areas, we are going to use same allowance for baseline and proposed case.

Best Regards.

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Johannes Gellrich Jul 02 2015 Guest 221 Thumbs Up

We had C&S retail spaces without lighting design, where we included the highest additionial lighting power, since this was the worst case in our eyes. the reviewers were of the opinion, that in cases, where no retail lighting has been designed, only the 18 W/m² without any additionial lighting should be chosen.
This was 1.5 years ago, since then we proceed in this way and never had a review comment on the 18 W/m².

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Marcus Sheffer LEED Fellow, 7group Jul 02 2015 LEEDuser Expert 57013 Thumbs Up

Adding more LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. and modeling it identically is certainly the conservative approach. For this reason alone the reviewer should allow you to do so. The higher the neutral, identical energy use, the lower the overall savings.

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Felipe Duran Jul 02 2015 LEEDuser Member 372 Thumbs Up

Thank you very much Johannes and Marcus.

Best Regards,

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Santiago Rodriguez REVITALIZA CONSULTORES
Jun 30 2015
Guest
957 Thumbs Up

Modeling fans for tenant areas for a C&S Project

Hello,

I did some research to find a similar question on this forum before posting it, but even though there were several questions related to the topic, I did not find the exact situation:

We are modeling a Core&Shell office building, the owner will install an HVAC system and will only deliver chilled water and outdoor air to the tenant spaces. The design guidelines will specify that Fan&coil units should be installed for all tenant spaces. For common areas, such as lobbies, the design includes the capacity and model of the corresponding fan&coil unit. The question is how to model the fans for the tenant areas, should we model them exactly as the baseline model? If not, assuming we model fan&coil units with auto-size capacities, the simulation results show a lot of energy savings in fan energy consumption (more than 70%). The pressure drop for the tenant fan&coil units, using the value of 0.35 W/cfm (same as the PFP boxes of the baseline model), gives us the same fan power for each tenant area, but for the baseline model there are also the air loop fans which deliver the air for each floor, and here is where the main difference in energy consumption comes from, since in the proposed model chilled water is delivered directly to each space. The power, pressure drop and fan efficiency of the baseline air loop fans are defined using the Appendix G Fan Power Calculator. I am not sure how to model the proposed model in order to obtain a reasonably fan energy savings. Any suggestions would be greatly appreciated.

Best Regards,
Santiago

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Marcus Sheffer LEED Fellow, 7group Jul 01 2015 LEEDuser Expert 57013 Thumbs Up

To claim energy savings you will need to have something required by the tenant lease agreement. Otherwise the parameter should be modeled identically. You can't just auto-size the fans and use only the allowance for the PFP boxes.

Requiring the installation of a fan/coil unit should be augmented with specific performance parameters relative to fan power (perhaps a W/cfm limit) in order to claim any energy savings. You will need to develop these requirements, require that tenants follow them, and justify the methodology you use to model it to the reviewer.

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Agata Mozer GO4IT SP Z OO SP K Jul 09 2015 LEEDuser Member 402 Thumbs Up

I have a similar problem. There won't be any lease agreement signed regarding fancoil units that the tenants will install in their spaces. The reference model has a 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. system with reheat so I can't model the proposed case (CAV with fancoils) in the same way as the reference case. Does it mean that we have to calculate the fan power of fancoil units based on the guidelines of section G3.1.2.9 (but without inclusion of fans in AHUs) assuming some level of pressure drop of the fancoil unit?

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