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:
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 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.
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 and CS Appendix 2: Energy Modeling Guidelines. In case of a conflict between ASHRAE and LEED guidelines, follow LEED.
Projects using district energy systems have special requirements. For EAp2, the proposed building must achieve the 10% energy savings without counting the effects of the district generation system. To earn points in EAc1 you can take advantage of the district system’s efficiency, but you have to run the energy model again to claim those benefits (see EAc1 for details).
While you could run the required energy model at the end of the design development phase, simply to demonstrate your prerequisite compliance, you don’t get the most value that way in terms of effort and expense. Instead, do it early in the design phase, and run several versions as you optimize your design. Running the model also gives you an opportunity to make improvements if your project finds itself below the required 10% savings threshold.
The baseline model is the designed building with mechanical systems specified in ASHRAE 90.1-2007, Appendix G, for the specific building type, with a window-to-wall ratio at a maximum of 40%, and minimally code-compliant specifications for the envelope, lighting, and mechanical components. It can be developed as soon as preliminary drawings are completed. The baseline is compared to the design case to provide a percentage of reduction in annual energy use. To avoid any bias from orientation, you need to run the baseline model in each of the four primary directions, and the average serves as your final baseline figure.
The design-case is modeled using the schematic design, orientation, and proposed window-to-wall ratio—¬the model will return design-case annual energy costs. Earn points by demonstrating percentage reductions in annual energy costs from the design to the baseline case. EAp2 is achieved if the design case is 10% lower than the baseline in new construction (or 5% less in existing building renovations).
Provide as much project and design detail to the modeler as possible. A checklist is typically developed by the energy modeler, listing all the construction details of the walls, roof, slabs, windows, mechanical systems, equipment efficiencies, occupancy load, and schedule of operations. Any additional relevant information or design changes should be brought to the modeler’s attention as soon as possible. The more realistic the energy model is, the more accurate the energy use figure, leading to better help with your design.
Invite energy modelers to project meetings. An experienced modeler can often assist in decision-making during design meetings, even without running complete models each time.
All known plug loads must be included in the model. The baseline and design-case models assume identical plug loads. If your project is deliberately attempting to reduce plug loads, demonstrate this by following the exceptional calculation method (ECM), as described in ASHRAE 90.1-2007, G2.5. Incorporate these results in the model to determine energy savings.
For items outside the owner’s control—like lighting layout, fans and pumps—the parameters for the design and baseline models must be identical.
It can take anywhere from a few days to a few weeks to generate meaningful energy modeling results. Schedule the due dates for modeling results so that they can inform your design process.
Review the rate structure from your electrical utility. The format can inform your team of the measures likely to be most effective in reducing energy costs, especially as they vary over season, peak load, and additional charges beyond minimum energy use.
Performing a cost-benefit analysis in conjunction with energy modeling can determine payback times for all the energy strategies, helping the iterative design process.
Using energy modeling only to check compliance after the design stage wastes much of the value of the service, and thus your investment.
The architect and mechanical engineer should carefully read the applicable ASHRAE Advanced Energy Design Guide for office, warehouse, or retail projects, as applicable.
Keep the owner abreast of the design decisions dictated by the standard. Fill in the team-developed checklist, within the climate zone table’s prescribed requirements, with appropriate envelope improvements, system efficiencies, and a configuration that meets the standard requirements.
As a prescriptive path, this option relies heavily on following the requirement checklist, which is used throughout the design process to track progress. To assist design development, provide all critical team members—not limited to the architect, mechanical and electrical engineers, and lighting designer—with a checklist highlighting their appointed tasks.
The architect, mechanical engineer, and lighting designer need to discuss each requirement and its design ramifications. Hold these meetings every six to eight weeks to discuss progress and make sure all requirements are being met.
Core and Shell projects must mandate the requirements for the tenant spaces within a tenant guideline document such as one developed for SSc9: Tenant Design and Construction Guidelines.
Confirm that your project team is comfortable with following all the prescribed requirements. If not, switch to Option 1: Whole Building Energy Simulation.
The LEED Online credit form does not specify how to document each prescriptive requirement because they are so different for each project; it only requires a signed confirmation by the MEP for meeting AEDG requirements. You still have to provide documentation. Submit your checklist of requirements, and supporting information for each item, through LEED Online to make your case. If your project fails to meet even one requirement, it will fail to earn the prerequisite, thus jeopardizing LEED certification.
Although energy modeling consultant costs are avoided by this option, additional staff time will be required to document and track compliance status, as compared with conventional projects.
Energy efficiency measures prescribed by the guide can be perceived as additional costs in comparison with conventional projects. However, they are easy to implement and are cost-effective pn the whole.
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.
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.
The architect and HVAC engineer should agree on the design, working with the cost estimator and owner.
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 Core and Shell Development
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
Useful web resource with information on local/regional incentives for energy-efficiency programs.
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.
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 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 CS-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.
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.
I did some research to find a similar question on this forum before posting it, but even though there were several questions related to the topic, I did not find the exact situation:
We are modeling a Core&Shell office building, the owner will install an HVAC system and will only deliver chilled water and outdoor air to the tenant spaces. The design guidelines will specify that Fan&coil units should be installed for all tenant spaces. For common areas, such as lobbies, the design includes the capacity and model of the corresponding fan&coil unit. The question is how to model the fans for the tenant areas, should we model them exactly as the baseline model? If not, assuming we model fan&coil units with auto-size capacities, the simulation results show a lot of energy savings in fan energy consumption (more than 70%). The pressure drop for the tenant fan&coil units, using the value of 0.35 W/cfm (same as the PFP boxes of the baseline model), gives us the same fan power for each tenant area, but for the baseline model there are also the air loop fans which deliver the air for each floor, and here is where the main difference in energy consumption comes from, since in the proposed model chilled water is delivered directly to each space. The power, pressure drop and fan efficiency of the baseline air loop fans are defined using the Appendix G Fan Power Calculator. I am not sure how to model the proposed model in order to obtain a reasonably fan energy savings. Any suggestions would be greatly appreciated.
We are working on a new shopping mall. as usually in my country, a anchor store (tenant deparment store) was first developed and constructed, and now is operating. The other common, concourse and stores spaces are being designed and the project will be a C&S with the owner scope only in common and concourse areas.
The tenant area that already exits is included in the scope of the LEED C&S certification, but is not in the scope of the owner. Should I demostrate compliance of this prerequisite for this are that is not in the owner scope? If so, Should I model this space even though is not in the owner scope with equipment that already exits?
There is any way I may exclude this tenat in the scope of the C&S certification shopping mall, I mean do not consider that space in any credit?
If it is a separate project you can exclude it. See the MPR Guidance for the details on how to do so.
Hi, I have an open office, restaurant, apartment for rent in the mixed use building project. Im confused with lighting control mandatory section 9.4 ASHRAE. Item 184.108.40.206 says automatic control device (timmer, occupancy sensor..) must be installed to shut off all light in all spaces. We have occupancy sensors in lobbies, public places of landlord but for tenant, Do we have to provide automatic lighting control for tenant? I think it is unnecessary to do so because we don't know how tenant fit out. Are tenants required to install automatic lighting control device as per item 220.127.116.11 or manual switches are enough to control their tenant spaces as per 18.104.22.168?
In an apartment Exemption a to 22.214.171.124 applies since it is 24 hour operation.
We have received our Design Final Review comments and the LEED reviewer has denied EAp2 because the proposed equipment capacities do not match the equipment schedules on the HVAC drawings. Our review comment indicates that the proposed fan power values should match the nominal horsepower for these motors per the mechanical schedules. I feel that this is incorrect. The proposed model should be based on the brake horsepower values, not the nominal motor horsepower values. Please let me know if I am incorrect about this. Also, 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 documentation that I can mention in our appeal.
It should be BHP.
The Proposed model should match the mechanical schedule and if it does not then an explanation should be provided. If the schedule includes just HP and the models indicates something else, like kW, the reviewer should make an assumed adjustment to HP to estimate BHP before converting to kW. We usually use about 85% then 0.746kW/HP. So if you do not provide the BHP.
No interpretation or other documentation should be needed for a HP-BHP-kW calculation. You could send a project team inquiry to GBCI about the review comment if you think the reviewer was in error.
I am running into a conundrum for a CS warehouse that will have no HVAC systems installed upon completion of the CS project. The only energy savings to document are for the envelope and lights. The building will have envelope values that exceed the nonresidential requirements of ASHRAE 90.1-2007.
When I calculate the proposed model on its own, the warehouse Btuh/SF would qualify it as semiheated, which would mean I could use the semiheated envelope values from 90.1-2007 in the baseline. However, when I enter those worse envelope values in the baseline model, the calculated capacity of the baseline model would qualify it as heated, which in itself wouldn’t be an issue except for the fact that (per review comments) the CFM in the proposed model must be equal to the baseline. Since deltaT is also the same for the proposed and baseline, overriding the proposed CFM to match baseline will result in the same capacity, therefore the proposed model would also be classified as heated and I can no longer use the semiheated envelope values.
According to the review the only way I can have a lower CFM in the proposed model is to indicate a CFM/fan power limitation in the lease agreement, which the owner doesn’t want to do.
So long story short, it seems like I’m stuck in a code loop. When I start out, my load calculation indicates the warehouse is semiheated. When I enter the semiheated envelope values in the baseline model, there are a series of requirements that make me adjust the proposed model so that it would then be considered heated. So my question is, which envelope values should I use in the baseline? Semiheated or heated?
I would greatly appreciate any advice you might have.
The determination of conditioned or semi-conditioned is based on the Proposed Case, not the Baseline. If the Proposed is semi-heated that use those insulation parameters in the Baseline.
If no HVAC has been designed then the Proposed uses the same system as the Baseline but the supply air cfm does not need to be identical in both models. In fact that and the capacities of the system would be auto-sized in both cases and should be different. The outside air cfm is supposed to be identical. Assuming this would be a heated only space use system 9 or 10 from 90.1-2010 via Adendum dn.
Thanks Marcus - very helpful. I agree 100% with what you're saying about the supply air being autosized in both the baseline and proposed models and that it would be different in each. In fact that is how I modeled it originally. However, I got a review comment back saying very specifically that the fan volume and power must be modeled identically between the proposed and baseline cases. They said the only way they can be different is if I have a fan CFM/power limitation in the lease agreement, but the owner doesn’t want to do that.
I wasn’t able to find anything in 90.1-2007 to substantiate the need to have the fan CFM/power identical for both cases. Table G3.1 does mention that where no HVAC systems exist they need to be identical, but I always took that to mean the system types have to be identical and the actual capacities, CFM, fan power, etc would be autosized based on the loads. Should I just report autosized fan CFM/power in the proposed and say they were autosized based on the loads? Should I question the validity of the comment in my response?
Unless all of the parameters in both models are identical (envelop and lighting) you should have different auto-sizing outcomes. Assuming that is not the case then the reviewer is wrong (it happens to all of us).
You model the systems with the identical methodology, not necessarily the same values.
Rather than just question the comment in the response, I would submit a project team inquiry via the web site - http://www.gbci.org/contact - and make your case there before you submit all of your responses.
I have a question regarding section G126.96.36.199 of Appendix G. This section says that "design supply airflow rates for the baseline building design shall be based on a supply-air-to-room-air temperature difference of 11C". If I understand it well, for cooling mode if the room temperature is 24C then the supply air in the AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition)
2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. should be 13C. The max supply air temperature, based on section G188.8.131.52 Supply Air Temperature Reset in this case should be 15.3C (13C+2.3C) - is that correct? And what about the heating mode? If the room temperature for system 5 and 7 is 21C then according to section G184.108.40.206 supply air temperature in the AHU should be 32C (21C +11C)? If this is correct then in our case the reference building will be using much more energy for heating than the design case.
We got a comment from GBCI that "the heating supply air delivered to each zone should be 11 degrees C higher than the setpoint" in the reference model (system 7). Could you confirm that?
Sounds right according to G220.127.116.11.
The baseline system is 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. (single duct) with reheat (system 7). The simulation program sizes the system based on cooling supply temperature - cooling mode is considered to be worse case than heating mode. That is why the temperature difference of 11C can be applied for cooling. Doesn't section G18.104.22.168 apply only to cooling mode in this case?
Yes. In all cases this is for cooling.
I'm asking about that because we received a comment from GBCI asking us to show that "the heating supply air delivered to each zone is 11 degrees C higher than the setpoint" according to G22.214.171.124 requirements. Did they make a mistake then?
I think so. I believe that the User's Manual has some information that clarifies this issue.
We are compiling the LEED submission for an office tower that may have multiple tenants on each floor.
Is it possible to claim tenant lighting energy efficiency savings through the inclusion of a lease requirement prior to any tenants actually being signed up? The credit asks for signed Lease agreements by both building owner and tenant which is of course not possible until tenants are actually signed up.
Would it be acceptable to provide the following documentation as evidence instead:
• Copy of generic Lease agreement that includes the above lighting efficiency requirement of tenants
• Cover letter signed by PTPR clarifying that office tenants are let to be signed up but that their Lease agreements will include the above lighting energy efficiency requirements
Yes you can provide a sample lease agreement along with a letter of commitment from the owner indicating that the sample will be used for all tenants.
Is there any official reference to this exception? Currently all forms with a provision to a lease agreement indicate that such an agreement has to be signed by both the developed and the tenant. That said would it be at the discretion of the reviewer to accept a sample of lease agreement along with a letter of commitment signed by the developer/owner only?
I am not sure if it is in writing anywhere. I can tell you that it is accepted by the reviewer in my experience. If not then every project would have to be fully leased before claiming any acceptable savings.
Thanks a lot Marcus!
Does LEED allow the modeler to claim savings for increased insulation on either the ductwork, piping, or equipment itself?
Sure. It is rarely claimed but certainly eligible.
I have a factory to be built for rent. Thus, this project goes for CS since we only build the shell. However, since we don't know the detail of a machine to be used (depend on the future tenant/customer). How should we model the process load for this factory? We have tried ASHRAE 90.1 user manual but it seem too low (0.25 W/sf). We afraid that the reviewer might not accept this baseline. Any documents or interpretation we should follow?
I am not aware of a source of this data you could use which would automatically be accepted by the reviewer.
The values in the User's Manual are just minimum base load values (see the note at the bottom of the table). I agree that you should be using a much higher value.
I assume that the general type of manufacturer would be known and if so you could develop an estimate of the process load based on the expectation of the type of tenant expected.
In the absence of any specific information I would also make sure that the process load is very high, say over 50% or more. This would be the conservative approach.
What if the project is a warehouse for rent. Can the process energy be lower? Let's say 25%.
A warehouse would be lower. It should not be arbitrarily set to 25%. How low would depend on the degree of automation associated with the warehouse. I have seen them below 25% quite often.
Currently I have a project in Malaysia that is going for LEED Core and Shell (2009), the project consists of multiple buildings but will be certified under one certificate. The project has 1 block of office tower (18 floors), 2 blocks of serviced apartment (28 floors each), 2 retail blocks (3 and 5 floors respectively).
This project will be using the baseline of System 8-VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. with PFP Boxes. Could you please advise what would be the baseline COP of the chilled water system? Referring to Table 6.8.1C in ASHRAE 90.1-2007, can I use the COP for “air cooled, with condenser, electrical operated” which is at COP=2.8?
My proposed design HVAC system is using VRV system or inverter multi split. However, based on clause G126.96.36.199, I must use the centrifugal chiller as my baseline. If this is the case, my building will not be qualified as LEED Building as it is very difficult for me to get the minimum 10% savings since my baseline COP would be 6.10.
Can you please kindly advise how can I get the minimum 10% savings if my HVAC is VRV system? Thanks.
Your baseline system sounds correct for the most part. The retail may be another system type depending on their area.
You cannot use an air cooled unit with a system 8. I do not know nearly enough about the project to advise you on how to get 10% savings.
Meaning to say, if myHVAC system falls under System 8, my baseline will be either using water-cooled screw or centrifugal chillers?
For your information, currently my proposed HVAC design will be a VRV system whereby it would definitely become a negative savings if to compare with a better COP used in baseline. Thus, i'm wondering how to get the minimum 10% savings if my proposed design is a VRV system which is to be compared with a chilled water plant.
Whether a screw or centrifugal chiller depends on the baseline model's calculated cooling capacity, see Table G188.8.131.52.
In an energy end use other than cooling I guess. Again I do not know enough about your project to advise you.
We have a school campus project (LEED NC MB) in Shanghai. The cooling source is from central cooling plant and the heating source is from Municipal steam. We want to use option 2 according to the DES guideline.
My question is how to model the heating source in baseline and proposed model. Both steam meter or hot water boiler? If use hot water boiler, how to determine the average efficiency?
Waiting for your feedback.
How you model this is explained in the DESv2. The baseline is according to Appendix G. It depends on the size of the project whether it will be a boiler or not. Steam or hot water depends on what the district heating delivers to you. If you convert steam to hot water then the baseline does that too. The proposed is a virtual plant which accounts for the upstream systems. The efficiency calculation is addressed in section 184.108.40.206.1.
Thank you for your response, but we still have some confusion. If central boilers are used for heat source, we can model the average efficiency of the upstream system. But the heat source is Municipal steam, we can't get the municipal boiler's information. We just know the stream project use. So how to calculate the average efficiency of upsteam system? Can we use steam meter for both Baseline and Designcase?
If you can't get the actual information from the municipal system then you use the default efficiencies in section 220.127.116.11.3.
Using the steam meter sounds like DESv2 Option 1.
Thank you Marcus! So we have to use natural gas for both Baseline and Proposed case although there are no natural gas used in project. The efficiency of Baseline boiler is 82% and virtual boiler is 70%, it seems unfair for these kinds of projects. T_T
See Section 18.104.22.168 which indicates that the fuel mix you use in your model should match the actual upstream DES fuel mix. If the fuel mix cannot be determined then it appears that gas would be used as a default. See Appendix C in DESv2.
You do pay a penalty for hooking up to an inefficient plant. They are assumed to be relatively inefficient unless shown to be otherwise. This is a conservative approach. You can always use option 1 to avoid this penalty.
I am stuck with an error from eQUEST. We have defined the proposed building and when we want to perform the compliance analysis the baseline is not generated and the analysis is not completed due to an error:
"Table look-up failed: AS901-07 Envelope (1,5) evaluating rule: Look up and default C-CFACTOR"
"Table look-up failed: AS901-07 Envelope (1,4) evaluating rule: Look up and default C-FFACTOR"
We do not know what to do and if it just a problem of the baseline generator or it is something else wrong in the model.
Thank you in advance and sunny regards.
Not sure what the issue is but you may have better luck on the eQUEST Users group at onebuilding.org
Is it possible to model the building on Energy Plus and the underground parking lot calculation do it by extraordinary calculations?
Also if it is a mixed use building, is it possible to model the commercial area in one file and the office space on another, due to the different approach in design for each of them.
It depends on the interrelationships between the spaces, if any.
My first question is why you would want to do separate calculations or separate models. In general it can take more time and add considerable complication. The underground parking will interact with the building above thermally and must be ventilated so I would model it. You can typically separate spaces within a single model by assigned certain spaces to a separate meter.
I am working in a project that had a previous consultant and we do not agree with the way the CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. shall be modeled. The building will be served by a natural gas power generator that will operate an indirect fired absorption chiller from 17:30 to 20:30.
The Proposed Case has been previously modeled with a generator operating from 17:30 to 20:30 on weekdays, and Baseline Building has been modeled without it. I understand that energy modeling for LEED does not allow this procedure. According to the latest document on this issue, Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 – Design & Construction, from 2010, a generator should have also been modeled for the Baseline case, from 17:30 to 20:30, but assuming separate production of electricity and thermal energy.
Is there a more recent modeling protocol on CHP? Is it allowed to take credit of peak shaving without CHP?
DESv2 only applies in the case where there is a larger plant serving multiple buildings. If your CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. is within the project then DESv2 does not apply.
I am not aware of any circumstances where the CHP gets modeled in the baseline when using the DESv2 or not.
There is additional guidance on CHP modeling within the Reference Guide. You can claim credit for peak shaving.
Hi, Marcus. Although it is not the case of a DES, the DESv2 is referenced as guidance. Refer to the Advanced Energy Modeling for LEED, Technical Manual v2.0, Sep 2011 Edition. Another document is referenced, this one for on-site CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. systems only, but I could not find it: "Methodology for Modeling Mombined Meat and Mower for EAp2/ EAc1 credit in LEED 2009" (July 18, 2011).
If you Google the document title it comes up (this is often the best way to search USGBC's web site) - http://www.usgbc.org/sites/default/files/Methodology%20for%20Modeling%20...
As far as I know this document is not longer used as guidance. The CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. guidance in the DES and in the Reference Guide is what you should be using.
We have submitted 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 for the project and according to the ruling USGBC gives credit to projects that use fossil fuel for peak shaving of purchased electric demand...
In our project location, it is clear that no tenants will go for a heating system. The base building is also designed for cooling only. Identical heating coils will be modeled in base and proposed case. In the tenant agreement, we are clearly advising the tenant to install standard 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. boxes. With this, can we exclude the modeling of PFP boxes in proposed case? PFP boxes will be modeled only in base case.
If there will be no heating system installed then adding heating coils (and setting the temperatures so they never come on) seems like a waste of time to me. Tell the reviewer that rather than add heating coils and a heating set point that would ensure that the heating would never run, that you have not modeled a heating system in either case.
Simply advising the tenant is not enough. You must require them to do so in the lease agreement. If you don't then the system gets modeled identically.
If no tenants have been identified can the project owner claim relevant energy saving from reduced lighting power density using a sample of lease agreement and a letter of commitment in lieu of lease agreement between the owner and the (future) tenant (which cannot be in effect at the time of project submission for LEED review)? Thank you in advance.
Yes. The reduced LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. needs to be required by the lease agreement.
Thank you Marcus!
Marcus, just to clarify the following issue: When selecting the option “Tenant Sales and/or Lease Agreement” it is required to provide the legally binding document (lease, sales agreement, tenant construction requirements, etc.) associated with the project, signed by both the developer and the tenant, explicitly stating the performance requirements for the tenant work. If no tenants have been identified can the project owner claim savings using a sample of lease agreement and a letter of commitment to the USGBC signed by the owner in lieu of lease agreement between the owner and the (future) tenant (which cannot be in effect at the time of project submission for LEED review)? Thank you in advance.
Does anyone know whether LED monitors for advertisement are considered as exterior lighting? Does it need to comply with the 2.2W/m2 Exterior LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. requirement as stipulated in ASHRAE 90.1?
We have a project that is designed to have a podium LED facade solely for advertisement, either stationary images or animation. Can it be excluded from the ASHRAE LPD requirement? Do I need to model the energy use of the LED podium box in our models?
Advertising signage is an exception (see Section 9.4.5 Exception b).
It is excluded from the exterior LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. requirements. It must be included in both models identically. The energy models must always include all the energy associated with the project.
we are developing a strategy to reach a C&S 2009 certification for a commercial building in Brazil. I've read the following from the USGB website:
"Option 4. Brazil compliance path: PBE Edifica
Projects in Brazil that are certified at the “A” level under the Regulation for Energy Efficiency Labeling (PBE Edifica) program for all attributes (Envelope, Lighting, HVAC) achieve this prerequisite."
My question is about how to achieve more points under the EAc1. Is there a possibility to get more points using the PBE Edifica alone? Is that necessary to perform a whole building simulation besides the PBE compliance in order to demonstrate further energy savings ?
Thank you in advance,
This option was added to the prerequisite only, so it does not appear that additional points are available for EAc1 when using this option. To get points you will need to follow one of the other available options for EAc1.
Many thanks Marcus!
We request for a clarification regarding mandating the tenant to use the 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. boxes in core and shell projects.
In a core and shell project, we will not know what system the tenant will be using. Is it right, if we use the same HVAC system as in baseline case for tenant areas?
If the project has a VAV with PFP boxes in baseline case, can the proposed case air side system be identical to baseline case? Do we have to mandate the VAV distribution to the tenants through tenant lease agreement?
If the HVAC in the tenant spaces has not been designed then you model the HVAC in those spaces identical to the baseline system. No need for a requirement in the tenant lease agreement. You only need a requirement in the tenant lease agreement if you are attempting to claim any savings over the baseline. Modeling the proposed identical to the baseline does not require the tenant to install 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., it just makes the HVAC neutral so it does not contribute to any energy savings.
Can you please confirm if the signed lease agreement page needs to include the tenant signature? I am asking specifically for CS projects that do not yet have the tenant on board, but do have the tenant lease agreement in place, with language specific to limiting lighting power densities (and other items). We can provide the signature page with the landlord/owner, just not the tenant yet. Please advise. Thanks!
No it does not need to include the tenant.
I am requesting help on the energy modeling protocol for a building both connected to a stand-alone plant and a district energy system.
I read a lot of posts on the forum before posting but I didn’t find an answer matching my project.
The project consists of building with a total area of around 500 000 sf, treated as a whole in Core and Shell v.2009.
The building includes two different activities : office Spaces (200 000 sf) and retail activities (around 300 000 sf).
Office spaces will be modelled as designed.
The HVAC systems are not known for retail spaces (but the heating and cooling source are), so the Baseline system will be also used for the proposed model (as mentioned in ashrae 90.1 Table G3.1).
Office spaces are supplied by a 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., providing around 80% of the annual heating and cooling energy. The energy backup will be provided by purchased energy (heating and cooling DES).
Retail spaces are only provided by purchased energy (heating and cooling DES), as the GSHP could not supply the whole building.
I read the USGBC Guidance for District thermal energy, but it is assuming the project is only supplied by a DES. Whereas the DES is used as a backup source in my project (for Offices spaces that is).
So my questions are as follows :
- Should I model 2 different systems for Offices and retail space (for proposed and Baseline), as the energy plant strategy is different (purchased energy used as primary source for retail, but as a backup for office spaces)
- How should I model the heating and cooling source of the Baseline(s) ? As purchased heat as suggested in USGBC Guidance, or as Boiler + Chiller (ashrae 90.1-2007 G3.1.1B for hybrid systems)?
Also a “hybrid System” is only defined in Ashrae 90.1-2007 as a mix fossil/Electric. Could it be extended as purchased energy/Electric?
For information , purchased energy is here provided by CPCU and Climespace, which are huge DES providing energy for hundred or maybe thousands buildings in Paris. They use using many plants and energy sources (CPCU use a mix of fuel, gas, waste to energy,…). We obviously can’t have access to the plants characteristics of these DES, thus option 1 of LEED Guidance will be used, in case of modelling the DES.
I would try modelling follows :
Proposed – Office spaces : Model as designed, with GSHP and Purchased heating and cooling as a backup
Baseline – Office Spaces : Purchased energy (and not boilers and chiller as suggested in ashrae 90.1-2007 Table G3.1.1B)
Proposed – retail spaces: Same system as the Baseline (system 7), provided with Purchased energy
Baseline – retail space : Purchased energy.
Sounds It right to you?
Thank you for reading my long post, and I would really be grateful if someone could give me some advice.
That sounds right. The only caveat is that the back up system must use energy in the proposed model. If it does not then it is no longer hybrid and the baseline would be a system #8.
Ok, I will check that point.
Thank you for the help !
If I were a reviewing this I'd want to understand what you mean by "back-up". If the back-up is only used in an emergency, I would not expect to see it in the model. But if the back up is to be used based on a regular schedule, or when certain conditions (say outdoor temperature within a specific range) exist then it should be accounted for.
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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.
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