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 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.
Energy 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:
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.
Passive 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.
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.
The Core Performance Guide path is a good option if all of the following are true:
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.
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.
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.
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.)
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.
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.
No, not for an existing building.
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.
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.
The energy savings are based on the whole building energy use—building and process. LEED does not stipulate exactly where they come from.
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.
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.
You can assume exterior lighting savings for canopies against the baseline, but not the shading effects of canopies.
If exterior lighting is present on the project site, consider it as a constant in both energy model cases.
Any conditioned area must be included in the energy model.
The Energy Star portion of the form does not apply to international projects.
Use the tables and definitions provided in 90.1 Appendix B to determine an equivalent ASHRAE climate zone.
International projects are not required to enter a Target Finder score. Target Finder is based on U.S. energy use data.
For Section 188.8.131.52c, a manual control device would be sufficient to comply with mandatory provisions.
Submitting these forms is not common; however, it can be beneficial if you are applying for any exceptions.
Use the building area method.
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.
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.
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.
If it is only used for backup and not for regular use such as peak shaving—no.
SHGC is not a mandatory provision so it is available for trade-off and can be higher than the baseline.
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.
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.
The prerequisite’s energy-reduction target of 10% is not common practice and is considered beyond code compliance.
Indirect 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:
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.
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.
Use 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:
The energy model itself will not account for any change in plug loads from the baseline case, even if your project is making a conscious effort to purchase Energy Star or other efficient equipment. Any improvement made in plug loads must be documented separately, using the exceptional calculation methodology (ECM), as described in ASHRAE 90.1-2007. These calculations determine the design case energy cost compared to the baseline case. They are included in the performance rating method (PRM) table or directly in the baseline and design case model.
Besides energy modeling, you may need to use the exceptional calculation methodology (ECM) when any of the following situations occur:
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.
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:
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.
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 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.
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:
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.
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:
Identify critical areas in which to reduce loads. For example, in a data center, the plug loads are the largest energy load. Small changes in lighting density might bring down the energy use but represent only a small fraction of annual energy use.
Don't forget that LEED (following ASHRAE) uses energy cost and not straight energy when it compares your design to a base case. That's important because you might choose to use a system that burns natural gas instead of electricity and come out with a lower cost, even though the on-site energy usage in kBtus or kWhs is higher. Generally you have to specify the same fuel in your design case and in the base case, however, so you can't simply switch fuels to show a cost savings
Explore and analyze design alternatives for energy use analyses to compare the cost-effectiveness of your design choices. For example, do you get better overall performance from a better window or from adding a PV panel? Will demand-control ventilation outperform increased ceiling insulation?
Simple, comparative energy analyses of conceptual design forms are useful ways to utilize an energy model at this stage. Sample scenarios include varying the area of east-facing windows and looking at 35% versus 55% glazing. Each scenario can be ranked by absolute energy use to make informed decisions during the design stage.
If your project is using BIM software, the model can be plugged into the energy analysis software to provide quick, real-time results and support better decisions.
Model development should be carried out following the PRM from ASHRAE 90.1-2007, Appendix G, and the LEED 2009 Design and Construction Reference Guide, Table in EAc1. In case of a conflict between ASHRAE and LEED guidelines, follow LEED.
Projects using district energy systems have special requirements. For EAp2, the proposed building must achieve the 10% energy savings without counting the effects of the district generation system. To earn points in EAc1 you can take advantage of the district system’s efficiency, but you have to run the energy model again to claim those benefits (see EAc1 for details).
While you could run the required energy model at the end of the design development phase, simply to demonstrate your prerequisite compliance, you don’t get the most value that way in terms of effort and expense. Instead, do it early in the design phase, and run several versions as you optimize your design. Running the model also gives you an opportunity to make improvements if your project finds itself below the required 10% savings threshold.
The baseline model is the designed building with mechanical systems specified in ASHRAE 90.1-2007, Appendix G, for the specific building type, with a window-to-wall ratio at a maximum of 40%, and minimally code-compliant specifications for the envelope, lighting, and mechanical components. It can be developed as soon as preliminary drawings are completed. The baseline is compared to the design case to provide a percentage of reduction in annual energy use. To avoid any bias from orientation, you need to run the baseline model in each of the four primary directions, and the average serves as your final baseline figure.
The design-case is modeled using the schematic design, orientation, and proposed window-to-wall ratio—¬the model will return design-case annual energy costs. Earn points by demonstrating percentage reductions in annual energy costs from the design to the baseline case. EAp2 is achieved if the design case is 10% lower than the baseline in new construction (or 5% less in existing building renovations).
Provide as much project and design detail to the modeler as possible. A checklist is typically developed by the energy modeler, listing all the construction details of the walls, roof, slabs, windows, mechanical systems, equipment efficiencies, occupancy load, and schedule of operations. Any additional relevant information or design changes should be brought to the modeler’s attention as soon as possible. The more realistic the energy model is, the more accurate the energy use figure, leading to better help with your design.
Invite energy modelers to project meetings. An experienced modeler can often assist in decision-making during design meetings, even without running complete models each time.
All known plug loads must be included in the model. The baseline and design-case models assume identical plug loads. If your project is deliberately attempting to reduce plug loads, demonstrate this by following the exceptional calculation method (ECM), as described in ASHRAE 90.1-2007, G2.5. Incorporate these results in the model to determine energy savings.
For items outside the owner’s control—like lighting layout, fans and pumps—the parameters for the design and baseline models must be identical.
It can take anywhere from a few days to a few weeks to generate meaningful energy modeling results. Schedule the due dates for modeling results so that they can inform your design process.
Review the rate structure from your electrical utility. The format can inform your team of the measures likely to be most effective in reducing energy costs, especially as they vary over season, peak load, and additional charges beyond minimum energy use.
Performing a cost-benefit analysis in conjunction with energy modeling can determine payback times for all the energy strategies, helping the iterative design process.
Using energy modeling only to check compliance after the design stage wastes much of the value of the service, and thus your investment.
The architect and mechanical engineer should carefully read the applicable ASHRAE Advanced Energy Design Guide for office, warehouse, or retail projects, as applicable.
Keep the owner abreast of the design decisions dictated by the standard. Fill in the team-developed checklist, within the climate zone table’s prescribed requirements, with appropriate envelope improvements, system efficiencies, and a configuration that meets the standard requirements.
As a prescriptive path, this option relies heavily on following the requirement checklist, which is used throughout the design process to track progress. To assist design development, provide all critical team members—not limited to the architect, mechanical and electrical engineers, and lighting designer—with a checklist highlighting their appointed tasks.
The architect, mechanical engineer, and lighting designer need to discuss each requirement and its design ramifications. Hold these meetings every six to eight weeks to discuss progress and make sure all requirements are being met.
Confirm that your project team is comfortable with following all the prescribed requirements. If not, switch to Option 1: Whole Building Energy Simulation.
The LEED Online credit form does not specify how to document each prescriptive requirement because they are so different for each project; it only requires a signed confirmation by the MEP for meeting AEDG requirements. You still have to provide documentation. Submit your checklist of requirements, and supporting information for each item, through LEED Online to make your case. If your project fails to meet even one requirement, it will fail to earn the prerequisite, thus jeopardizing LEED certification.
Although energy modeling consultant costs are avoided by this option, additional staff time will be required to document and track compliance status, as compared with conventional projects.
Energy efficiency measures prescribed by the guide can be perceived as additional costs in comparison with conventional projects. However, they are easy to implement and are cost-effective pn the whole.
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.
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.
The modeler completes the energy analysis of the selected design and system and offers alternative scenarios for discussion. The modeler presents the energy cost reduction results to the team, identifying the LEED threshold achieved.
It’s helpful for the energy modeling report to include a simple payback analysis to assist the owner in making an informed decision on the operational savings of recommended features.
The architect and HVAC engineer should agree on the design, working with the cost estimator and owner.
Demonstrating reductions in non-regulated loads requires a rigorous definition of the baseline case. The loads must be totally equivalent, in terms of functionality, to the proposed design case. For example, reducing the number of computers in the building does not qualify as a legitimate reduction in non-regulated loads. However, the substitution of laptops for desktop computers, and utilization of flat-screen displays instead of CRTs for the same number of computers, may qualify as a reduction.
Residential and hospitality projects that use low-flow showers, lavatories, and kitchen sinks (contributing to WEp1) benefit from lower energy use due to reduced overall demand for hot water. However, for energy-savings calculations, these are considered process loads that must be modeled as identical in baseline and design cases, or you have the choice of demonstrating the savings with ECM for process loads.
Perform daylight calculations in conjunction with energy modeling to balance the potentially competing goals of more daylight versus higher solar-heat gain resulting in high cooling loads.
If your project is pursuing renewable energy, the energy generated is accounted for by using the PRM. These results provide information about whether the energy is contributing to EAc2: Onsite Renewable Energy.
A cost-benefit analysis can help the owner understand the return on investment of big-ticket, energy-conserving equipment that lowers operating energy bills with a quick payback.
Complete at least half of the energy modeling effort by the end of the design development stage. Help the design team to finalize strategy through intensive, early efforts in energy modeling. Once the team has a design direction, the modeler can develop a second model during the construction documents phase for final confirmation.
If pursuing ECM for non-regulated loads, calculate energy saving for each measure separately if you are, for example, installing an energy-efficient elevator instead of a typical one so that the reduction would contribute to total building energy savings. Calculate the anticipated energy use of the typical elevator in kBTUs or kWh. Using the same occupancy load, calculate the energy use of the efficient elevator. Incorporate the savings into design case energy use within the PRM. Refer to the ECM strategy for detailed calculation guidelines.
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.
The mechanical engineer, lighting consultant, and architect revisit the checklist for an update on the requirements and how they are being integrated into the design. All prescriptive requirements should be specifically incorporated into the design by the end of the design development phase.
The mechanical engineer and architect track the status of each requirement.
While the LEED Online credit form does not require detailed documentation for each Core Performance Guide requirement, it is important that each item be documented as required and reviewed by the rest of the team to confirm compliance, especially as further documentation may be requested by during review. Your design team should work with the owner to identify cost-effective strategies from Section 3 that can be pursued for the project.
Construction documents 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.
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.
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.
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.
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.
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.
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.
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.
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.
Excerpted from LEED 2009 for New Construction and Major Renovations
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.
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:
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.
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.
The building must meet the following requirements:
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:
Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone.
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.
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.
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
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.
Useful web resource with information on local/regional incentives for energy-efficiency programs.
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.
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.
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.
Research center at RPI provides access to a wide range of daylighting resources, case studies, design tools, reports, publications and more.
International association of energy modelers with various national and local chapters.
Non-profit organization aiming at design community to increase collaboration for designing energy efficient buildings.
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.
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.
This website discusses the step-by-step process for energy modeling.
This online resource, supported by Natural Resources Canada, presents energy-efficient technologies, strategies for commercial buildings, and pertinent case studies.
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.
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.
Free download of AHSRAE energy savings guide, use for Option 2.
Research warehouse for strategies and case studies of energy efficiency in buildings.
An online window selection tool with performance characteristics.
This website lays out design process for developing an energy efficient building.
This website discusses ways to improve design for lower energy demand as they relate to the AIA 2030 challenge.
This website includes discussion of design issues, materials and assemblies, window design decisions and case studies.
This site lists multiple web-based and downloadable tools that can be used for energy analyses.
This database is maintainted by the California Energy Commission and lists resources related to energy use and efficiency.
Energy design tools are available to be used for free online or available to download.
This website lists performance characteristics for various envelope materials.
This is an online forum of discussion for energy efficiency, computer model software users.
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.
This directory provides information on 406 building software tools for evaluating energy efficiency, renewable energy, and sustainability in buildings.
Weather data for more than 2100 locations are available in EnergyPlus weather format.
Weather data for U.S. and Non-U.S. locations in BIN format.
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.
A guide for achieving energy efficiency in new commercial buildings, referenced in the LEED energy credits.
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.
This document is USGBC’s second (v2.0) major release of guidance for district or campus thermal energy in LEED, and is a unified set of guidance comprising the following an update to the original Version 1.0 guidance released May 2008 for LEED v2.x and the initial release of formal guidance for LEED v2009.
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.
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).
Required reference document for DES systems in LEED energy credits.
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 statistics from the U.S. government.
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.
This website offers information on energy efficiency in buildings, highlighting success stories, breakthrough technology, and policy updates.
Bimonthly publication on case studies and new technologies for energy efficiency in commercial buildings.
AIA publication highlighting local and state green building incentives.
2008 guidelines and performance goals from the National Science and Technology Council.
Information about energy-efficient building practices available in EDR's Design Briefs, Design Guidelines, Case Studies, and Technology Overviews.
DOE tools for whole building analyses, including energy simulation, load calculation, renewable energy, retrofit analysis and green buildings tools.
This is a computer program that predicts the one-dimensional transfer of heat and moisture.
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.
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.
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.
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.
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.
In your supporting documentation, include spec sheets of equipment described in the Option 1 energy model or Options 2–3 prescriptive paths.
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.
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.
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.)
The climate zones shown on this Department of Energy map are relevant to all options for this credit.
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.
The following links take you to the public, informational versions of the dynamic LEED Online forms for each NC-2009 EA credit. You'll need to fill out the live versions of these forms on LEED Online for each credit you hope to earn.
Version 4 forms (newest):
Version 3 forms:
These links are posted by LEEDuser with USGBC's permission. USGBC has certain usage restrictsions for these forms; for more information, visit LEED Online and click "Sample Forms Download."
Documentation for this credit can be part of a Design Phase submittal.
This question is basically for the energy modelers out there who use HAP or any other software.
I have a conditioned lobby where the fan coil just uses the return air, according to our calculations the door can provide enough OA CFM for ventilation. However, I am not sure if I should input the value of the required CFM in HAP or just leave the OA CFM blank there since it will not be conditioned.
You will need to model the outside air. You need to model it either through the unit or as extra air infiltration. As far as HAP goes you might ask them or post this question on the HAP Users listserve at onebuilding.org
For a renovation and addition to an existing college campus library, we are in the process of determining the boundary to use for energy performance. The existing building is 182,738 SF. The total renovated building with additions will be 200,556 SF and the total area to include renovations and additions is 39,122 SF which equals approximately 19.5% of the entire building when complete, with the remaining 80.5% being outside of the project scope.
Can the base case energy model just include the area to be renovated (modeled on ASHRAE 90.1 prescriptive requirements)?
Can the design case energy model just include the renovated areas and additions (as designed)?
The models need to include the area of the project that aligns with the LEED project boundary. Both models would need to include the renovated and added areas. It can get tricky depending on the HVAC systems. Will there be separate systems serving the renovated and new areas? If there is HVAC overlap it can get very messy.
The renovated area can include the existing envelop parameters but the other systems are the Appendix G requirements.
Great, thank you for your suggestions Marcus. For clarification, with regards to your last sentence, we wanted to confirm that this applies to the base case and that any differences in the design case would be modeled as designed?
Yep the baseline is according to Appendix G and the proposed is modeled as designed.
We are doing a project which is being 10% retrofitted. The reviewer wants us to used the envelope values before retrofitting as baseline and the new envelope properties as the proposed project. So I was wondering, since the changes mostly involve exterior walls and the new type of walls do not vary too much from the previous existing walls do I have to use Ashare 90.1 Appendix A values? The reason I ask is because since the components of the wall are not too different with Appendix A I wont be able to demonstrate a difference between before and after retrofit components. The reviewer has not mentioned Appendix A anywhere though, but Im just asking from experience with other projects.
You have to account for the effect of any framing or structural elements in the wall assembly. That is what Appendix A does. If is does not apply in your case demonstrate to the reviewer that is does not apply. If there is not much difference using Appendix A there should also not be much of a difference using another method.
So how do the before and after wall differ?
I have a question from our energy modelling team. The question is about baseline HVAC systems modelling.
ASHRAE 90.1, appendix G, point G3.1.1 requires modelling systems 5-8 one per floor. In accordance with point G184.108.40.206 requirement design airflow rates shall be based on a supply-air-to-room-air temperature difference of 11°C (20°F). In a modeled building, there are groups of rooms with deferent heating and cooling 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. on each floor. If we model one system for all rooms on one floor, we will not complete point G220.127.116.11 requirement (temperature difference) for some rooms. Do we need to divide the system into several separate systems on one floor in this case?
When faced with a conflict in the modeling protocol it is up to you to suggest a solution. In general the more conservative (lower savings overall) the coutcome the more likely that the method would be acceptable.
With that said I think you have three options. The first two are probably the most conservative, the last one would still likely be acceptable.
1. Model one system and use the lowest cooling set point for the entire system
2. Model separate systems of the same system type for the spaces with the different set points.
3. Determine a weighted average set point and use this for the entire system.
In any case just provide a narrative justification to the reviewer.
When the project is pursuing the increase ventilation which ventilation rates have to be used for the baseline 62.1 or 62.1 + 30%?
I am working in LEED V2009. ASHRAE 90.1-2007
The baseline ventilation rates must match the proposed ventilation rates per A90.1 paragraph G18.104.22.168. The only exception to this is when modeling demand control ventilation, if it is not required in the baseline per section 22.214.171.124. So, if you are designing for increased ventilation, your baseline will also have the increased ventilation.
Thanks Laura. I was asking that because I am using a sofware that autogenerate baseline model. However for the baseline, it always uses 62.1 ventilation rates even though I used 62.1+30% in the proposed model. I contacted the sofware support. They told me that baseline builder used to match the airflows with IEQc2, but they received comments from USGBC saying that the baseline should not have the increased airflow for the EAc1 analysis.
Now I had to increase the BL ventilation rates manually.
In 90.1-2007 Laura is correct.
In 90.1-2010 the baseline is 62.1 and the proposed is as designed.
Maybe the software is confusing the two?
I'd like to ask you for your opinion and advice about applying these values following the case described below.
In LEED glossary such spaces are determined as 25 people per 100 sq ft.
When applying DCV however, this value is 40 per 1000 sq. ft.
The confusion comes, because both ratios are called "Densely occupied space".
When it concerns IEQp1, normally the reviewers are OK with 40 per 1000 ratio, but sometimes they say that because the ratio exceeds 25 per 1000, in such rooms there should be CO2Carbon dioxide sensors.
Normally these sensors are controlling DCV (which compiles to 40 per 1000 ratio).
If there is no DCV, because of ratio of 30 per 1000 (example) and by applying CO2 sensors, what these sensors are going to control in such situation?
Could you please advice what could be the explanation to reviewers when they are referring to comply to 25 per 1000 ratio. Should IEQp1 be revised to reflect it, although there is no DCV required or designed.
The issue of densely occupied does not impact EQp1.
The 40/100 in spaces over 500 sf is the threshold in 90.1 for having to install DCV in the baseline model. Reviewers will often look to the EQp1 documentation to determine if there are spaces in the baseline model that would require DCV.
The 25/1000 is used within EQc1 to determine if you need CO2Carbon dioxide or airflow monitoring. The reviewer should only be commenting on this issue within EQc1 and not within EQp1. Again they could be looking to EQp1 to see if there are spaces that would require CO2 sensors.
40/100 would be the building's elevator (which is technically the critical zone when performing EQp1 calculations)
For Non-Residential fenestration system that are designed to be
field glazed or field assembled units for compliance with ASHRAE 90.1-2010, the supplier provides a certificate according to NFRC procedures. The NFRC ratings is based on individual product simulated and have outside dimensions measuring 2000 mm x 2000 mm (NFRC Size for Glazed Wall/Sloped Glazing).
For calculating the building envelope performance for the proposed building according to Appendix G, 90-1 2007, should the energy model use NRFC ratings (U-Factor, SHGCSolar heat gain coefficient (SHGC): The fraction of solar gain admitted through a window, expressed as a number between 0 and 1., TvisVisible light transmittance (VLT) (Tvis) is the ratio of total transmitted light to total incident light (i.e., the amount of visible spectrum, 380780 nanometers of light passing through a glazing surface divided by the amount of light striking the glazing surface). The higher the Tvis value, the more incident light passes through the glazing.) using standard NFRC size, regardless of actual size of the fenestration systems?
There is usually more than on way to model the windows and frames. You can model the whole assembly values or you can separate the frames and the glazing. We will typically do the later as it tends to be more accurate. This will take size into account. Using a single NFRC value for all windows may be reasonably accurate if the window sizes to not vary to a significant degree. If they do vary significantly I would not use that method.
Perhaps this warrants a formal interpretation. When you specify and purchase fenestrations, you use the rated NRFC fenestration values that is tested and simulated at NRFC standard sizes. For code compliance with 90.1-2010, you use the rated fenestration values in Comcheck. It would only make sense to use rated fenestration values when you rate buildings to Appendix G. For design of mechanical systems, you should make the adjustment for fenestration size.
Glass manufacturers submit test reports in accordance with EN410 and EN673 for glass. And the S/Cs submit test reports for glass and frame.
To the best of my understanding from your comments and after reading ASRAE 90.1-2007 since the values we have received are tested in compliance with EN410 and EN673 I should ask for values calculated and tested as per NFRC.
I just wanted to make sure.
Thanks and regards.
Not all windows are NFRC rated for the whole assembly (curtainwall for example). International projects do not use windows that are required to be NFRC rated. As I said there are appropriate situations where using the NFRC data is appropriate but there are situations where it is not IMO. The LEED reviewers will accept several different methodologies for the determination of the window performance values. NFRC is just one way, but not the only way.
The thermal modeller scope is limited to detailed design, and at this stage Renewable energy (PV and Solar Water Heating) is still not 100% finalized / decided. Is it acceptable to present a thermal modelling report excluding renewable energies and enter separately kWhA kilowatt-hour is a unit of work or energy, measured as 1 kilowatt (1,000 watts) of power expended for 1 hour. One kWh is equivalent to 3,412 Btu. produced by renewable in leedonline form at a later stage with supporting documentation? Thanks
You can add it later. You could add it for the final review or if you are doing a split submission you can add it during the construction preliminary review if you can legitimately claim that it was added during construction.
OK thanks Marcus
Based on the App G fan curve, if we have a oversized 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. supply fan, the power usage will be lower than a properly sized fan.
For example, need 5k cfm
a 10k cfm fan operate at 0.5 load, corresponding power is 0.3 of full load based on G126.96.36.199.
a 5k fan will use 100% of its full load power.
And a 10k cfm fan will have full load power twice of the 5k cfm fan since they are sized based on the same pressure drop, the only difference is the cfm. Am I correct or I am missing something?
I have a project that will be conditioned by a water-cooled chiller and boiler plant located in one of the building that will be rated. It also provides chilled and hot water to another building that is rated and one that will not be rated by LEED. I have seen references to looking a the campus application guide but can't find it on the USGBC website. I have reviewed the Treatment of District Thermal Energy for LEED v2009. Any help on how to model a virtual plant as prescribed by Option 2 Modeling section would be appreciated. I am using HAP 4.8.
Here is the Campus Guide - http://www.usgbc.org/resources/campus-guidance
Perhaps you could come back with a more focused question.
Thanks for the response.
Let's start here, If the plant equipment in my building serves other buildings do I need to treat the plant and model the systems in accordance with guidelines for DES?
The use of DESv2 is not required but it provides helpful guidance for how to model district systems.
When entering District Energy System into the EAp2 Section Table 1-4 xcell sheet do I stop at purchased chilled and hot water or do I enter the proposed chiller and boiler plants into the sheet and leave the base line blank?
My model used Option #1 from the DESv2 guide.
Under Option 1 you enter the water side parameters that apply in both models. Neither model has a boiler or a chiller plant however. A pipe enters the building delivering hot and/or chilled water. You include all the system components downstream of that.
The Bird's Eye View comments on this page indicate that the USGBC will allow projects to meet the 10% minimum energy performance threshold with onsite renewable energy. Is there a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide or other reference from the USGBC in writing with this guidance for a LEED 2009 NC project?
I am not aware of one but maybe there is. Try searching the Interpretations database.
I think this may be a case of "it is not prohibited" so it is allowed. In v4 I think this loophole was closed by requiring that the project minus the renewable contribution meets the minimum level of performance.
I'm modeling a district heating system according to option 2 of “Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 – Design & Construction”. In the proposed model I'm going to model a virtual on-site hot water boiler, according to Table 4 of the document. Since the real district heating is fueled by agricultural crops, I can consider it as renewable energy (see page 15 of “Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 – Design & Construction”).
For the baseline model I have to consider System 7 (according to Table G3.1.1A of ASHRAE 90.1).
What fuel shall I consider in the baseline model?
Since in the real plant there is a system (another district system) that is fueled by natural gas and that can be considered a backup system, shall I model natural gas for the baseline model? The use of natural gas is very common in Italy (I would say, it's the “standard solution”).
The modeling rules say that you will need to use the same rate for district heating in both models. Assuming the district system fuels are qualified renewables you can clearly count them toward EAc2. The question is if you can count them also under EAp2/EAc1. Since these renewables have a cost associated with them and the metric for EAp2/EAc1 is cost one could easily make the case that they should not count.
I would try one of two options. Submit the "savings" related to comparing this DES rate to the natural gas rate as an exceptional calculation making the case that this is a valid comparison in your situation. Alternatively you could look at this document -http://www.usgbc.org/resources/treatment-scandinavian-district-energy-systems-leed-v1-2012-0 - which has been approved for European projects and allows a fossil fuel baseline.
I have a dormitory project which has a few cooling only spaces. Being residential and with the requirement to model cooling only spaces as if they had electric heat, this pushes the baseline to System Type 2, or PTHPs. My question is: how do you model the baseline and proposed systems with identical heating when the proposed system is not 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.? Any help would be much appreciated.
Hello. How is the proposed building heated?
Not sure we have enough information to provide you with an answer.
What is the nature of the cooling only spaces? What type of system is cooling these spaces in the proposed? Not sure why a few cooling only spaces changes the overall baseline, or maybe it does not? Are you applying a G3.1.1 exception?
There is a work around for the requirement to add heating or cooling to a space. Simply set the temperature in the space so that the system does not operate. As long as the setting is identical this is allowed. Once you know this you can usually explain to the reviewer that you know about this work around and did not want to waste your time modeling a system that does not exist in the Proposed.
We have a project in which they are attempting to use EnergyPro to show compliance for credits EAp2 and EAc1. Has LEED been accepting of EnergyPro models for this credit, when it does not allow for very detailed inputs into the model, vs. more complex software like eQuest or Design Builder? If we submit an EnergyPro model, since it automatically generates the baseline model for you, how do we fill out all the info for the Excel sheet Section 1.4 Tables for LEED, if we don't know the inputs they used? Does LEED still require this Excel sheet if you submit an EnergyPro model?
Also, the energy model was previously built on EnergyPro version 6 (188.8.131.52), which only allows for simulations vs. ASHRAE 90.1 - 2010. While EnergyPro version 5 allows for simulations vs. ASHRAE 90.1 - 2007, it does not allow you do open models created in version 6 or allow you to backsave down to version 5, once it's been opened in version 6. Would LEED accept an EnergyPro model ran on EnergyPro version 6 against ASHRAE 90.1 - 2010, since it should be stricter than 2007 anyways? Or will we need to start over from scratch either on EnergyPro version 5 or another program such as eQuest or Design Builder?
EnergyPro meets the Title 24/Appendix G criteria for acceptable modeling software. You can still see the input summary reports within the software. Many of them are in the .sim file which is generated for every DOE2 software. For a 90.1 submission a summary of the inputs are still required. For a Title 24 submission provide the required Title 24 reports summarized on the EAp2 form.
It would probably be acceptable to use the 90.1-2010 baseline but you will likely be losing points in LEED.
Check with Energy Pro Support regarding opening the file in Version 5. I have ran models created for Title 24 2013 (version 6) in Title 24 2005 (Version 5) for LEED with a bit of tweaking.
Thank you. Yes, we have found out that in June they released a version of EnergyPro 5 (v184.108.40.206), that will allow you to open files from EnergyPro version 6, while previously it did not allow you to do this, so we should be able to use this software to run it against the proper standard.
Our project includes a separate non-LEED certifiable building with no regularly occupied space and no FTEFull-time equivalent (FTE) represents a regular building occupant who spends 8 hours a day (40 hours a week) in the project building. Part-time or overtime occupants have FTE values based on their hours per day divided by 8 (or hours per week divided by 40). Transient Occupants can be reported as either daily totals or as part of the FTE. Residential occupancy should be estimated based on the number and size of units. Core and Shell projects should refer to the default occupancy table in the Reference Guide appendix. All occupant assumptions must be consistent across all credits in all categories., that houses the renewable energy and ground source heat pumpA type of heat pump that uses the natural heat storage ability of the earth and/or the groundwater to heat and/or cool a building. The earth has the ability to absorb and store heat energy from the sun. To use that stored energy, heat is extracted from the earth through a liquid medium (groundwater or an anti-freeze solution) and is pumped to the heat pump or heat exchanger. There, the heat is used to heat the building. In the summer, the process is reversed and indoor heat is extracted from the building and transferred to the earth through the liquid. The geothermal heat pump is more efficient than an air-source heat pump. Also referred to as a "closed-loop" system. systems for the main building, as well as charging stations for a fleet of 6 electric vehicles, and the recycling and trash storage, general storage, and one small bathroom. The building is minimally conditioned to keep pipes from freezing.
I understand we need to model this ancillary building for EAp2 and EAc1, even though the ASHRAE 90.1 definition would technically deem it unconditioned, according to our mech engineer (cooling capacity below 5 BtuA unit of energy consumed by or delivered to a building. A Btu is an acronym for British thermal unit and is defined as the amount of energy required to increase the temperature of 1 pound of water by 1 degree Fahrenheit, at normal atmospheric pressure. Energy consumption is expressed in Btu to allow for consumption comparisons among fuels that are measured in different units./h.ft2 and heating capacity below 20 Btu/h.ft2).
I have 3 unique questions:
1) Are we interpreting the LEED requirements accurately, assuming that we do need to model this second building? Are there any suggestions or cautions for modeling and documenting two buildings for one LEED submittal?
2) Should we also include the building in the Gross Floor AreaGross floor area (based on ASHRAE definition) is the sum of the floor areas of the spaces within the building, including basements, mezzanine and intermediate‐floored tiers, and penthouses wi th headroom height of 7.5 ft (2.2 meters) or greater. Measurements m ust be taken from the exterior 39 faces of exterior walls OR from the centerline of walls separating buildings, OR (for LEED CI certifying spaces) from the centerline of walls separating spaces. Excludes non‐en closed (or non‐enclosable) roofed‐over areas such as exterior covered walkways, porches, terraces or steps, roof overhangs, and similar features. Excludes air shafts, pipe trenches, and chimneys. Excludes floor area dedicated to the parking and circulation of motor vehicles. ( Note that while excluded features may not be part of the gross floor area, and therefore technically not a part of the LEED project building, they may still be required to be a part of the overall LEED project and subject to MPRs, prerequisites, and credits.) (GFA) under the project info forms, which calculates building-to-site area for MPR-7 (as well as several other credits)? I see that the GFA definition excludes vehicle parking, so maybe the area of the ancillary building should only be applied to EA credits (yes/no)? If yes, how do we differentiate the area included/excluded, since the PIf2 is linked to the EA credits?
3) Do we need to account for the vehicle charging stations in the building which will use a portion of the solar energy generated on site. If so, how would we go about estimating and entering this energy load into the model and/or LEED form?
The 90.1 definition of unconditioned space is not accurate. The parameters you indicate define fully conditioned space. Semiheated spaces >3.4BTU/h.sf are still considered "conditioned" spaces. Anything that is not fully conditioned or semiheated is considered unconditioned. I would guess your spaces are semiheated and should follow the 90.1 requirements as such.
1. Yes it should be included in the model. I would just include it in the same model and the larger building. It would probably be a good idea to model this building on separate meters within the model. You could model it in a separate model and add them together as well.
2. Yes any conditioned or semiheated space should be included in all credits for consistency. Unconditioned parking is not included in the GFA but should be noted. The reviewer will be expecting the GFA reported for the model to be within 10% of the total GFA.
3. Yes you need to account for all energy use within and associated with the project. If this load is outside conditioned spaces you could do the calculations outside the modeling software and simply add the results to the modeling results. If it is within conditioned space then you will need to add this load within the model as well.
How do you treat naturally ventilated, occupied, interior space with no mechanical heating or cooling? Do you count it as conditioned or unconditioned? Do you include its area in the Gross Floor AreaGross floor area (based on ASHRAE definition) is the sum of the floor areas of the spaces within the building, including basements, mezzanine and intermediate‐floored tiers, and penthouses wi th headroom height of 7.5 ft (2.2 meters) or greater. Measurements m ust be taken from the exterior 39 faces of exterior walls OR from the centerline of walls separating buildings, OR (for LEED CI certifying spaces) from the centerline of walls separating spaces. Excludes non‐en closed (or non‐enclosable) roofed‐over areas such as exterior covered walkways, porches, terraces or steps, roof overhangs, and similar features. Excludes air shafts, pipe trenches, and chimneys. Excludes floor area dedicated to the parking and circulation of motor vehicles. ( Note that while excluded features may not be part of the gross floor area, and therefore technically not a part of the LEED project building, they may still be required to be a part of the overall LEED project and subject to MPRs, prerequisites, and credits.)?
It is unconditioned space by definition. The most common occurrence we see would be in a warehouse. Since it is regularly occupied space it counts toward the GFA for LEED.
Here in 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. 5, few spaces besides warehouses are likely to use natural ventilation without mechanical heating or cooling. In some other climates, might many other space types fall into this category?
In such cases, there could be more than 10% difference between the energy model GFA and the project’s total GFA.
Would naturally ventilated spaces that use passive heating and cooling strategies also qualify as unconditioned?
Some climates can get away with it but the prevalence I see is more cultural. Many international projects in warm or mild climates use natural ventilation for 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.. I have seen many international projects submitted for LEED from many different space types that do not have heating or cooling systems. Not so much in the US.
There could be more than a 10% difference. If there is it should be explained. In an unconditioned warehouse you still have lighting, ventilation, and other equipment loads. These need to be modeled but because they do not necessarily have interactive effects with other energy end uses, they do not necessarily need to be modeled in a space depending on the strategies employed.
If naturally ventilated spaces do not have installed heating or cooling then they are considered unconditioned.
I have also seen questions about how to treat mechanical chases, airshafts, and atria.
As I understand it, mechanical chases that are inside the building enclosure count toward Gross Floor AreaGross floor area (based on ASHRAE definition) is the sum of the floor areas of the spaces within the building, including basements, mezzanine and intermediate‐floored tiers, and penthouses wi th headroom height of 7.5 ft (2.2 meters) or greater. Measurements m ust be taken from the exterior 39 faces of exterior walls OR from the centerline of walls separating buildings, OR (for LEED CI certifying spaces) from the centerline of walls separating spaces. Excludes non‐en closed (or non‐enclosable) roofed‐over areas such as exterior covered walkways, porches, terraces or steps, roof overhangs, and similar features. Excludes air shafts, pipe trenches, and chimneys. Excludes floor area dedicated to the parking and circulation of motor vehicles. ( Note that while excluded features may not be part of the gross floor area, and therefore technically not a part of the LEED project building, they may still be required to be a part of the overall LEED project and subject to MPRs, prerequisites, and credits.) (but not net area). Since they are inside the weather barrier, IEQc4 Indoor Air Quality restrictions would apply, but I am not sure how to treat chases in energy models. Would these be unconditioned space—part of that 10% gap between Project GFA and Conditioned GFA?
By contrast, airshafts and light wells are generally open to the sky, so they are exterior space. They do not figure into GFA or the IEQc4 credits.
Finally, in an interior, multistory space like an atrium, the floor area only counts once in the GFA and in the model. Thus, you would model a three-story lobby as one very tall room, not as three spaces stacked on top of one another. (I worked with a newbie modeler who inadvertently did the latter. This effectively tripled the square-footage and the energy load of the atrium and doubled the Building GFA. That was a bit more than 10%.)
Does this just about cover the ins-and-outs of reconciling energy models with Project GFA?
Most chases are like interior partitions. They would be part of the difference between gross and net.
One potential issue with chases is that some can have a relatively significant impact on energy use. Elevators in a high rise building come to mind. They basically are large interior chimneys that can have a major impact on air movement in and out of the building, especially if they are vented at the top. In certain situations I think that they should be modeled since they will impact energy use.
The most important thing is to make sure your model accurately reflects all of the items which will impact energy use. If you look at these issues in that light you will always understand what is the right thing to do.
Shall the mandatory efficiency of section 6.4 (Tables 6.8.1) be verified also for a chiller that works as backup system (the chilled water is provided in normal conditions by district cooling)?
Probably a good idea. If it will not normally operate at all and function as an emergency back up then you may be able to argue that it would not have to meet it.
We have a building that contains both existing and new construction. I wonder how we should determine the LEED points we will achieve given certain percentage savings. Is it based on 60% rule?
Thanks in advance
The % savings is calculated based on a weighted average of new to existing area for the project. So for example if the area is 50% new and 50% existing you would split the difference between the 10% (new) and 5% (existing) and would need 7.5% to meet the prerequisite requirements.
Thanks Marcus. How we should document this on LEED online? It doesnt give us an option to input the savings for new and existing separately. Instead, it automatically calculate the savings and points achieved.
Also, the building has three part: new, renovated existing and unrenovated portion.
The prerequisite form will accurately calculate the percentage and points based on the ratio of new to existing area. This information gets entered in one of the project information forms and automatically transfers to the EAp2 form within LEED Online.
Let me elaborate my question: I can enter the % of new and existing floor area but cant enter the savings % for them. Also, I modeled all those spaces in the same model so I don't know if it is possible to separate the savings for each portion. Especially the cooling, heating and fan energy cannot be separated easily since they have non-linear curve. And another thing is that, once we have the savings, say 15% prorated, how many points should we get? Are we using New buildings or existing threshold?
I wonder if the reviewer can accept if the building has more than 60% existing area, we can use the existing building threshold
You don't enter the % savings. The form calculates it.
You don't separate the savings for each portion. The weighted average is applied to the total.
You are using a blend of new and existing to determine the thresholds for the points. In my previous example (50% new, 50% existing) the prerequisite starts at 7.5%, 1 point would be 10%, 2 points would be 12%, 6 points would be 20%, etc. Basically you are creating your own set of thresholds for the points based on the ratio of new to existing in your project.
No a 60% existing area cannot use the existing thresholds. It just does not work that way.
Thanks for the clarification Marcus. It is clear to me now.
My building has full T24 certification.
I take it this will be satisfactory to achieve this Prereq?
Maybe but probably not.
What version of T24? Either way you still need to show a 10% new, 5% renovation savings to meet this prerequisite.
Sorry, I should have explained more.
This is in ref to a retrospective 2009 NC LEED certification project. The building in question is now occupied, and we are going through the LEED process.
As part of the process of making this a ''zero net energy'' building, and as part of satisfying the local Californian code, 2013 Title 24 certification was undertaken and achieved.
Is it our understanding that under LEED, one should follow the local regulations if they are more rigorous, of which Title 24 is.
The T24 work shows the build is 35% more energy efficient than the LEED (Ashrae) baseline.
So, this should satisfy this prerequisite no? And also get us awarded under Credit 1 Optimize Energy Perf, no?
One thing that we did want clarity on also was in that Credit, the language useds says ''Whole Building energy Modelling''.
Now, while one of those isnt part of the T24, all the component parts are ie Envelope, Heating, Lighting, HVAC etc is assessed and data metrics under weather condistions produced.
So again, T24 should be fine for this prereq and Credit 1 no?
Many thanks for you help
You cannot claim LEED compliance based on a generalized comparison of the relative stringency of the codes. While the average may be 35% the range is far wider. You might be able to convince the reviewer that you meet the prerequisite but that is not a sure thing. You will not be able to claim any points under EAc1 without the modeling results.
We wouldnt be claiming anything, doesnt the LEED documentation state ''...use Ashrae or your local code, whichever is more rigorous..'' or something to that effect?
The T24 process produced data metrics on all the items that an Energy Model would have done also, albeit in a slightly different format.
So on both the Prereq and the Credit 1, I am a touch perplexed.
You would be claiming that your Title 24-2013 compliance is 35% better than 90.1 as you state above, so you are claiming something.
LEED does make reference to other codes, but that is relative to code compliance in your jurisdiction. That does not substitute for LEED compliance.
So it sounds like you have demonstrated Title 24 compliance prescriptively, correct? If you demonstrated it using the ACM performance path you would already have a model. The model is required for LEED. You have three options - see the credit language above. Virtually all projects choose Option 1. Read the requirements, they are very clear on this subject.
The Green Engineer, LLP
EAc1 relies directly on the EAp2 documentation, and the strategies to earn the prerequisite are often similar to earning points under the credit.
Limits on interior and exterior light use can help in reducing energy loads.
Daylighting reduces demand on installation and use of lighting fixtures resulting in energy use. To full realize the energy benefits, contorl electrical lighting with daylight sensors.
Commissioning of energy-efficient building systems helps realize he operational benefits of the design.
Onsite renewable energy contributes to prerequisite achievement if pursuing energy modeling under Option 1.
The computer model developed for EAp2 – Option 1 is used in the M&V plan.
Do you know which LEED credits have the most LEED Interpretations and addenda, and which have none? The Missing Manual does. Check here first to see where you need to update yourself, and share the link with your team.
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