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 18.104.22.168c, a manual control device would be sufficient to comply with mandatory provisions.
Submitting these forms is not common; however, it can be beneficial if you are applying for any exceptions.
Use the building area method.
Although there is no formal list of approved simulation tools, there are a few requirements per G2.2.1, including the ability of the program to provide hourly simulation for 8760 hours per year, and model ten or more thermal zones, which PHPP does not meet.
The automated Trace 700 report provides less information than is requested by the Section 1.4 tables spreadsheet. The Section 1.4 tables spreadsheet must be completed.
Assign HVAC systems as per Appendix-G and Section 6 but set thermostatic setpointsSetpoints are normal operating ranges for building systems and indoor environmental quality. When the building systems are outside of their normal operating range, action is taken by the building operator or automation system. out of range so that systems never turn on.
If it is only used for backup and not for regular use such as peak shaving—no.
SHGC is not a mandatory provision so it is available for trade-off and can be higher than the baseline.
You generally wouldn't need to upload any documentation, but particularly for a non-U.S. project, it may help to provide a short narrative about what they are based on.
Discuss your project’s energy performance objectives, along with how those are shaping design decisions, with the owner. Record energy targets in the Owners Project Requirements (OPR) for the commissioning credits EAp1 and EAc3.
You won’t earn this prerequisite by accident. The energy efficiency requirements here are typically much more stringent than local codes, so plan on giving it special attention with your team, including leadership from the owner.
Consider stating goals in terms of minimum efficiency levels and specific payback periods. For example: “Our goal is to exceed a 20% reduction from ASHRAE 90.1, with all efficiency measures having a payback period of 10 years or less.”
Develop a precedent for energy targets by conducting research on similar building types and using the EPA’s Target Finder program. (See Resources.)
For Option 1 only, you will need to comply with the mandatory requirements of ASHRAE 90.1-2007, to bring your project to the minimum level of performance. The ASHRAE 90.1-2007 User’s Manual is a great resource, with illustrated examples of solutions for meeting the requirements.
ASHRAE 90.1-2007 has some additional requirements compared with 2004. Read through the standard for a complete update. The following are some samples.
The prerequisite’s energy-reduction target of 10% is not common practice and is considered beyond code compliance.
Indirect sunlight delievered through clerestories like this helps reduce lighting loads as well as cooling loads. Photo – YRG Sustainability, Project – Cooper Union, New York A poorly designed envelope with a high-tech HVAC system is not, on the whole, efficient or cost-effective. Start with building orientation and passive design features first when looking for energy efficiency. Also look at envelope design, such as energy-efficient windows, walls and roof, before looking at HVAC and plug loads. HVAC may also be a good place to improve performance with more efficient equipment, but first reducing loads with smaller equipment can lead to even greater operational and upfront savings. A poorly designed envelope with a high-tech HVAC system is not, on the whole, efficient or cost-effective.
Don’t plan on using onsite renewable energy generation (see EAc2) to make your building energy-efficient. It is almost always more cost-effective to make an efficient building, and then to add renewables like photovoltaics as the “icing” on the cake.
Some rules of thumb to reduce energy use are:
Find the best credit compliance path based on your building type and energy-efficiency targets. Use the following considerations, noting that some projects are more suited to a prescriptive approach than others.
Option 1: Whole Building Energy Simulation requires estimating the energy use of the whole building over a calendar year, using methodology established by ASHRAE 90.1-2007, Appendix G. Option 1 establishes a computer model of the building’s architectural design and all mechanical, electrical, domestic hot water, plug load, and other energy-consuming systems and devices. The model incorporates the occupancy load and a schedule representing projected usage in order to predict energy use. This compliance path does not prescribe any technology or strategy, but requires a minimum reduction in total energy cost of 10% (5% for an existing building), compared to a baseline building with the same form and design but using systems compliant with ASHRAE 90.1-2007. You can earn additional LEED points through EAc1 for cost reductions of 12% and greater (8% for existing buildings).
Option 2: Prescriptive Compliance Path: ASHRAE Advanced Energy Design Guide refers to design guides published by ASHRAE for office, school, warehouse, and retail projects. These guides outline strategies to reduce energy use by 30% from ASHRAE 90.1-2001 levels, or an amount equivalent to a 10%–14% reduction from the ASHRAE 90.1-2007 standard. If you choose this compliance path, become familiar with the list of prescriptive requirements and commit to meeting them. (See the AEDG checklist in the Documentation Toolkit.)
Option 3: Prescriptive Compliance Path: Advanced Buildings Core Performance Guide is another, more basic prescriptive path. It’s a good option if your project is smaller than 100,000 ft2, cannot pursue Option 2 (because there is not an ASHRAE guide for the building type), is not a healthcare facility, lab, or warehouse—or you would rather not commit to the energy modeling required for Option 1. Your project can be of any other building type (such as office or retail). To meet the prerequisite, you must comply with all requirements within Sections 1 and 2 of the guide. If you choose this path, become familiar with the list of activities and requirements and commit to meeting them. (See Resources for a link to the Core Performance Guide and the Documentation Toolkit for the checklist of prescriptive items.)
EAc1: Optimize Energy Performance uses the same structure of Options 1–3, so it makes sense to think about the credit and the prerequisite together when making your choice. In EAc1, Option 1 offers the potential for far more points than Options 2 and 3, so if you see your project as a likely candidate for earning those points, Option 1 may be best.
Hotels, multifamily residential, and unconventional commercial buildings may not be eligible for either Option 2 or Option 3, because the prescriptive guidance of these paths was not intended for them. Complex projects, unconventional building types, off-grid projects, or those with high energy-reduction goals are better off pursuing Option 1, which provides the opportunity to explore more flexible and innovative efficiency strategies and to trade off high-energy uses for lower ones.
If your project combines new construction and existing building renovation then whatever portion contains more than 50% of the floor area would determine the energy thresholds.
Options 2 and 3 are suitable for small, conventional building types that may not have as much to gain from detailed energy modeling with Option 1.
Meeting the prescriptive requirements of Options 2 and 3 is not common practice and requires a high degree of attention to detail by your project team. (See the Documentation Toolkit for the Core Performance Guide Checklist.) These paths are more straightforward than Option 1, but don’t think of them as easy.
Options 2 and 3 require additional consultant time from architects and MEP engineers over typical design commitment, which means higher upfront costs.
Option 1 references the mandatory requirements of ASHRAE 90.1-2007, which are more stringent than earlier LEED rating systems that referred to ASHRAE 90.1-2004.
Option 1 energy simulation provides monthly and annual operating energy use and cost breakdowns. You can complete multiple iterations, refining energy-efficiency strategies each time. Payback periods can be quickly computed for efficiency strategies using their additional first costs. A building’s life is assumed to be 60 years. A payback period of five years is considered a very good choice, and 10 years is typically considered reasonable. Consult the OPR for your owners’ goals while selecting your efficiency strategies.
Option 1 energy simulation often requires hiring an energy modeling consultant, adding a cost (although this ranges, it is typically on the order of $0.10–$0.50/ft2 depending on the complexity). However, these fees produce high value in terms of design and decision-making assistance, and especially for complex or larger projects can be well worth the investment.
All compliance path options may require both the architectural and engineering teams to take some time in addition to project management to review the prescriptive checklists, fill out the LEED Online credit form, and develop the compliance document.
The architect, mechanical engineer, and lighting designer need to familiarize themselves and confirm compliance with the mandatory requirements of ASHRAE 90.1-2007, sections 5–9.
Use simple computer tools like SketchUp and Green Building Studio that are now available with energy analysis plug-ins to generate a first-order estimate of building energy use within a climate context and to identify a design direction. Note that you may need to refer to different software may not be the one used to develop complete the whole building energy simulations necessary for LEED certification.
Energy modeling can inform your project team from the start of design. Early on, review site climate data—such as temperature, humidity and wind, available from most energy software—as a team. Evaluate the site context and the microclimate, noting the effects of neighboring buildings, bodies of water, and vegetation. Estimate the distribution of energy across major end uses (such as space heating and cooling, lighting, plug loads, hot water, and any additional energy uses), targeting high-energy-use areas to focus on during design.
Use a preliminary energy use breakdown like this one to identify target areas for energy savings.Perform preliminary energy modeling in advance of the schematic design phase kick-off meeting or design charrette. The energy use breakdown can help identify targets for energy savings and point toward possible alternatives.
For existing buildings, the baseline energy model can reflect the pre-renovation features like rather than a minimally ASHRAE-compliant building. This will help you achieve additional savings in comparison with the baseline.
Projects generating renewable energy onsite should use Option 1 to best demonstrate EAp2 compliance and maximize points under EAc1. Other options are possible but won’t provide as much benefit. Like any other project, model the baseline case as a system compliant with ASHRAE 90.1-2007, using grid-connected electricity, and the design case is an “as-designed” system also using grid-connected electricity. You then plug in 100% onsite renewable energy in the final energy-cost comparison table, as required by the performance rating method (PRM) or the modeling protocol of ASHRRAE 90.1 2007, Appendix G. (Refer to the sample PRM tables in the Documentation Toolkit for taking account of onsite renewable energy.
LEED divides energy-using systems into two categories:
The energy model itself will not account for any change in plug loads from the baseline case, even if your project is making a conscious effort to purchase Energy Star or other efficient equipment. Any improvement made in plug loads must be documented separately, using the exceptional calculation methodology (ECM), as described in ASHRAE 90.1-2007. These calculations determine the design case energy cost compared to the baseline case. They are included in the performance rating method (PRM) table or directly in the baseline and design case model.
Besides energy modeling, you may need to use the exceptional calculation methodology (ECM) when any of the following situations occur:
Some energy-modeling software tools have a daylight-modeling capability. Using the same model for both energy and IEQc8.1: Daylight and Views—Daylight can greatly reduce the cost of your modeling efforts.
Provide a copy of the AEDG for office, retail, or warehouse, as applicable, to each team member as everyone, including the architect, mechanical and electrical engineers, lighting designer, and commissioning agents, are responsible for ensuring compliance. These are available to download free from the ASHRAE website. (See Resources.)
Find your climate zone before attempting to meet any detailed prescriptive requirements. Climate zones vary by county, so be sure to select the right one. (See the Documentation Toolkit for a list of climate zones by county.)
Develop a checklist of all requirements, and assign responsible team members to accomplish them. Hold a meeting to walk the team through the AEDG checklist for your project’s climate zone. Clarify specific design goals and prescriptive requirements in the OPR for EAp1: Fundamental Commissioning.
Early access to the AEDG by each team member avoids last-minute changes that can have cascading, and costly, effects across many building systems.
The AEDG prescriptive requirements include:
If your project team is not comfortable following these guidelines, consider switching to Option 1, which gives you more flexibility.
Although Option 2 is generally lower cost during the design phase than energy modeling, the compliance path is top heavy—it requires additional meeting time upfront for key design members.
Provide a copy of the New Buildings Institute Advanced Buildings: Core Performance Guide to each team member. The guide is available to download free from the NBI website. (See Resources.)
The guide provides practical design assistance that can be used throughout the design process.
Walk your team through the project checklist to clarify design goals and prescriptive requirements.
The guide provides an outline for approaching an energy-efficient design, in addition to a list of prescriptive measures. The first of its three sections emphasizes process and team interaction rather than specific building systems or features. Advise the owner to read through the guide in order to understand what is required of the architect and engineers.
Section 1 in the guide focuses on best practices that benefit the project during the pre-design and schematic design stages, such as analyzing alternative designs and writing the owner’s project requirements (OPR).
Section 2 of the Core Performance Guide describes architectural, lighting, and mechanical systems to be included. Section 3 is not required for EAp2 but includes additional opportunities for energy savings that can earn EAc1 points.
The guide mandates that your team develop a minimum of three different design concepts to select from for best energy use.
Though they can be a little daunting at first glance, a majority of the guide’s requirements overlap with other LEED credits, such as EAp1: Fundamental Commissioning, IEQp1: Minimum Indoor Air Quality Performance, and IEQc6.1: Controllability of Systems—Lighting Controls.
This compliance path is top-heavy due to upfront consultant time, but it provides adequate structure to ensure that your project is in compliance with the prerequisite requirements. For some projects it may be less expensive to pursue than Option 1.
The owner should now have finalized the OPR with the support of the architect, as part of the commissioning credits EAp1 and EAc3. The goals identified here will help your team identify energy-reduction and occupant-comfort strategies.
Consider a broad range of energy-efficiency strategies and tools, including passive solar, daylighting, cooling-load reduction, and natural ventilation to reduce heating and cooling loads.
Develop the basis of design (BOD) document in conjunction with your mechanical engineer and architect for EAp1: Fundamental Commissioning, noting key design parameters to help strategize design direction as outlined in the OPR.
The OPR and BOD serve the larger purpose of documenting the owner’s vision and your team’s ideas to meet those goals. The BOD is intended to be a work-in-progress and should be updated at all key milestones in your project. Writing the document gives you an opportunity to capture the owner’s goals, whether just to meet the prerequisite or to achieve points under EAc1.
Confirm that your chosen compliance path is the most appropriate for your project, and make any changes now. Following a review with the design team and owner, ensure that everyone is on board with contracting an energy modeler for Option 1 or meeting all the prescriptive requirements under Options 2 or 3.
Sometimes teams change from Option 1 to Options 2 or 3 very late in the design phase for various reasons including not realizing the cost of energy modeling. Making that change is risky, though: the prescriptive paths are all-or-nothing—you must comply with every item, without exception. Evaluate each requirement and consult with the contractor and estimator to ensure the inclusion of all activities within project management.
To avoid costly, last-minute decisions, develop a comprehensive, component-based cost model as a decision matrix for your project. The model will help establish additional cost requirements for each energy conservation measure. It will also illustrate cost reductions from decreased equipment size, construction rendered unnecessary by energy conservation measures, and reduced architectural provisions for space and equipment access. (See the Documentation Toolkit for an example.)
Use envelope design and passive strategies to reduce the heating and cooling loads prior to detailed design of HVAC systems. Passive strategies can reduce heating and cooling loads, giving the engineer more options, including smaller or innovative systems.
Load reduction requires coordinated efforts by all design members including the architect, lighting designer, interior designer, information-technology manager, and owner.
Involving facilities staff in the design process can further inform key design decisions, helping ensure successful operation and low maintenance costs.
Encourage your design team to brainstorm design innovations and energy-reduction strategies. This provides a communication link among team members so they can make informed decisions.
More energy-efficient HVAC equipment can cost more relative to conventional equipment. However, by reducing heating and cooling loads through good passive design, the mechanical engineer can often reduce the size and cost of the system. Reduced system size can save money through:
Review case studies of similar energy-efficient buildings in the same climate to provide helpful hints for selecting energy-efficiency measures. For example, a building in a heating-dominated climate can often benefit from natural ventilation and free cooling during shoulder seasons. (See Resources for leading industry journals showcasing success stories around the country and internationally.)
The relationship between first costs and operating costs can be complex. For example, more efficient windows will be more expensive, but could reduce the size and cost of mechanical equipment. A more efficient HVAC system may be more expensive, but will reduce operating costs. Play around with variables and different strategies to get the right fit for the building and the owner’s goals as stated in the OPR.
Review and confirm compliance with the mandatory requirements of all the relevant sections of ASHRAE 90.1-2007
Trust your project’s energy modeling task to a mechanical firm with a proven track record in using models as design tools, and experience with your building type.
Contract an energy modeling team for the project. These services may be provided by the mechanical engineering firm on the design team or by an outside consultant. Software used for detailed energy use analysis and submitted for final LEED certification must be accepted by the regulatory authority with jurisdiction, and must comply with paragraph G2.2 of ASHRAE Standard 90.1-2007. Refer to Resources for a list of Department of Energy approved energy-analysis software that may be used for LEED projects.
Design team members, including the architect and mechanical engineer at a minimum, need to work together to identify a percentage improvement goal for project energy use over the ASHRAE 90.1-2007-compliant baseline model. The percentage should be at least 10% to meet the prerequisite.
Plan on initiating energy modeling during the design process, and use it to inform your design—preferably executing several iterations of the design as you improve the modeled energy performance.
Ask the modeling consultant to develop an annual energy-use breakdown—in order to pick the “fattest” targets for energy reduction. A typical energy-use breakdown required for LEED submission and ASHRAE protocol includes:
Identify critical areas in which to reduce loads. For example, in a data center, the plug loads are the largest energy load. Small changes in lighting density might bring down the energy use but represent only a small fraction of annual energy use.
Don't forget that LEED (following ASHRAE) uses energy cost and not straight energy when it compares your design to a base case. That's important because you might choose to use a system that burns natural gas instead of electricity and come out with a lower cost, even though the on-site energy usage in kBtus or kWhs is higher. Generally you have to specify the same fuel in your design case and in the base case, however, so you can't simply switch fuels to show a cost savings
Explore and analyze design alternatives for energy use analyses to compare the cost-effectiveness of your design choices. For example, do you get better overall performance from a better window or from adding a PV panel? Will demand-control ventilation outperform increased ceiling insulation?
Simple, comparative energy analyses of conceptual design forms are useful ways to utilize an energy model at this stage. Sample scenarios include varying the area of east-facing windows and looking at 35% versus 55% glazing. Each scenario can be ranked by absolute energy use to make informed decisions during the design stage.
If your project is using BIM software, the model can be plugged into the energy analysis software to provide quick, real-time results and support better decisions.
Model development should be carried out following the PRM from ASHRAE 90.1-2007, Appendix G, and the LEED 2009 Design and Construction Reference Guide, Table in EAc1. In case of a conflict between ASHRAE and LEED guidelines, follow LEED.
Projects using district energy systems have special requirements. For EAp2, the proposed building must achieve the 10% energy savings without counting the effects of the district generation system. To earn points in EAc1 you can take advantage of the district system’s efficiency, but you have to run the energy model again to claim those benefits (see EAc1 for details).
While you could run the required energy model at the end of the design development phase, simply to demonstrate your prerequisite compliance, you don’t get the most value that way in terms of effort and expense. Instead, do it early in the design phase, and run several versions as you optimize your design. Running the model also gives you an opportunity to make improvements if your project finds itself below the required 10% savings threshold.
The baseline model is the designed building with mechanical systems specified in ASHRAE 90.1-2007, Appendix G, for the specific building type, with a window-to-wall ratio at a maximum of 40%, and minimally code-compliant specifications for the envelope, lighting, and mechanical components. It can be developed as soon as preliminary drawings are completed. The baseline is compared to the design case to provide a percentage of reduction in annual energy use. To avoid any bias from orientation, you need to run the baseline model in each of the four primary directions, and the average serves as your final baseline figure.
The design-case is modeled using the schematic design, orientation, and proposed window-to-wall ratio—¬the model will return design-case annual energy costs. Earn points by demonstrating percentage reductions in annual energy costs from the design to the baseline case. EAp2 is achieved if the design case is 10% lower than the baseline in new construction (or 5% less in existing building renovations).
Provide as much project and design detail to the modeler as possible. A checklist is typically developed by the energy modeler, listing all the construction details of the walls, roof, slabs, windows, mechanical systems, equipment efficiencies, occupancy load, and schedule of operations. Any additional relevant information or design changes should be brought to the modeler’s attention as soon as possible. The more realistic the energy model is, the more accurate the energy use figure, leading to better help with your design.
Invite energy modelers to project meetings. An experienced modeler can often assist in decision-making during design meetings, even without running complete models each time.
All known plug loads must be included in the model. The baseline and design-case models assume identical plug loads. If your project is deliberately attempting to reduce plug loads, demonstrate this by following the exceptional calculation method (ECM), as described in ASHRAE 90.1-2007, G2.5. Incorporate these results in the model to determine energy savings.
For items outside the owner’s control—like lighting layout, fans and pumps—the parameters for the design and baseline models must be identical.
It can take anywhere from a few days to a few weeks to generate meaningful energy modeling results. Schedule the due dates for modeling results so that they can inform your design process.
Review the rate structure from your electrical utility. The format can inform your team of the measures likely to be most effective in reducing energy costs, especially as they vary over season, peak load, and additional charges beyond minimum energy use.
Performing a cost-benefit analysis in conjunction with energy modeling can determine payback times for all the energy strategies, helping the iterative design process.
Using energy modeling only to check compliance after the design stage wastes much of the value of the service, and thus your investment.
The architect and mechanical engineer should carefully read the applicable ASHRAE Advanced Energy Design Guide for office, warehouse, or retail projects, as applicable.
Keep the owner abreast of the design decisions dictated by the standard. Fill in the team-developed checklist, within the climate zone table’s prescribed requirements, with appropriate envelope improvements, system efficiencies, and a configuration that meets the standard requirements.
As a prescriptive path, this option relies heavily on following the requirement checklist, which is used throughout the design process to track progress. To assist design development, provide all critical team members—not limited to the architect, mechanical and electrical engineers, and lighting designer—with a checklist highlighting their appointed tasks.
The architect, mechanical engineer, and lighting designer need to discuss each requirement and its design ramifications. Hold these meetings every six to eight weeks to discuss progress and make sure all requirements are being met.
Confirm that your project team is comfortable with following all the prescribed requirements. If not, switch to Option 1: Whole Building Energy Simulation.
The LEED Online credit form does not specify how to document each prescriptive requirement because they are so different for each project; it only requires a signed confirmation by the MEP for meeting AEDG requirements. You still have to provide documentation. Submit your checklist of requirements, and supporting information for each item, through LEED Online to make your case. If your project fails to meet even one requirement, it will fail to earn the prerequisite, thus jeopardizing LEED certification.
Although energy modeling consultant costs are avoided by this option, additional staff time will be required to document and track compliance status, as compared with conventional projects.
Energy efficiency measures prescribed by the guide can be perceived as additional costs in comparison with conventional projects. However, they are easy to implement and are cost-effective pn the whole.
Become familiar with the Core Performance Guide early in the design phase to know the multiple requirements and all requisite documents.
Note that the guide demands additional time, attention, and integrated process from the design team as compared to conventional projects. It’s not just a list of prescriptive requirements, but a prescribed process for achieving energy efficiency goals. LEED Online documentation requires proof of all steps outlined in Sections 1 and 2, including three conceptual design options and meeting minutes. The project manager, architect, and mechanical engineer should read the complete Core Performance Guide carefully to know beforehand the prescriptive requirements in Sections 1 and 2.
The project manager must take responsibility for ensuring that the requirement checklist is on track.
For Section 3, the design team needs to identify three or more of the listed strategies as possible targets for the project.
Create a checklist of requirements and assign a responsible party to each item.
The Core Performance Guide requires an integrated design contributed by the architect, mechanical and electrical engineers, and lighting designer. The project manager must take responsibility for shepherding and documenting the collaborative process to demonstrate compliance.
A long documentation list can be overwhelming for your team, so create a detailed checklist with tasks delegated to individual team members, allowing each member to focus on assigned tasks. The checklist can function as a status tracking document and, finally, the deliverable for LEED Online.
The architect and engineer, and other project team members, continue to develop a high-performance building envelope with efficient mechanical and lighting systems.
Constant communication and feedback among project team members, owner, and if possible, operational staff, during design development can minimize construction as well as operational costs and keep your project on schedule.
If you change or go through value-engineering on any specifications, such as the solar-heat gain coefficient of glazing, for example, be aware of impacts on mechanical system sizing. Making changes like this might not pay off as much as it first appears.
Consider using building information modeling (BIM) tools to keep design decisions up to date and well documented for all team members.
Schedule delays can be avoided if all team members share their ideas and update documents during the design development process.
The modeler completes the energy analysis of the selected design and system and offers alternative scenarios for discussion. The modeler presents the energy cost reduction results to the team, identifying the LEED threshold achieved.
It’s helpful for the energy modeling report to include a simple payback analysis to assist the owner in making an informed decision on the operational savings of recommended features.
The architect and HVAC engineer should agree on the design, working with the cost estimator and owner.
Demonstrating reductions in non-regulated loads requires a rigorous definition of the baseline case. The loads must be totally equivalent, in terms of functionality, to the proposed design case. For example, reducing the number of computers in the building does not qualify as a legitimate reduction in non-regulated loads. However, the substitution of laptops for desktop computers, and utilization of flat-screen displays instead of CRTs for the same number of computers, may qualify as a reduction.
Residential and hospitality projects that use low-flow showers, lavatories, and kitchen sinks (contributing to WEp1) benefit from lower energy use due to reduced overall demand for hot water. However, for energy-savings calculations, these are considered process loads that must be modeled as identical in baseline and design cases, or you have the choice of demonstrating the savings with ECM for process loads.
Perform daylight calculations in conjunction with energy modeling to balance the potentially competing goals of more daylight versus higher solar-heat gain resulting in high cooling loads.
If your project is pursuing renewable energy, the energy generated is accounted for by using the PRM. These results provide information about whether the energy is contributing to EAc2: Onsite Renewable Energy.
A cost-benefit analysis can help the owner understand the return on investment of big-ticket, energy-conserving equipment that lowers operating energy bills with a quick payback.
Complete at least half of the energy modeling effort by the end of the design development stage. Help the design team to finalize strategy through intensive, early efforts in energy modeling. Once the team has a design direction, the modeler can develop a second model during the construction documents phase for final confirmation.
If pursuing ECM for non-regulated loads, calculate energy saving for each measure separately if you are, for example, installing an energy-efficient elevator instead of a typical one so that the reduction would contribute to total building energy savings. Calculate the anticipated energy use of the typical elevator in kBTUs or kWh. Using the same occupancy load, calculate the energy use of the efficient elevator. Incorporate the savings into design case energy use within the PRM. Refer to the ECM strategy for detailed calculation guidelines.
Ensure that all prescriptive requirements are incorporated into the design by the end of the design development stage.
Revisit the Advanced Energy Design Guides (AEDG) checklist to ensure that the design meets the prescriptive requirements.
The mechanical engineer, lighting consultant, and architect revisit the checklist for an update on the requirements and how they are being integrated into the design. All prescriptive requirements should be specifically incorporated into the design by the end of the design development phase.
The mechanical engineer and architect track the status of each requirement.
While the LEED Online credit form does not require detailed documentation for each Core Performance Guide requirement, it is important that each item be documented as required and reviewed by the rest of the team to confirm compliance, especially as further documentation may be requested by during review. Your design team should work with the owner to identify cost-effective strategies from Section 3 that can be pursued for the project.
Construction documents clearly detail the architectural and mechanical systems that address energy-efficiency strategies.
Confirm that specifications and the bid package integrate all equipment and activities associated with the project.
If the project goes through value engineering, refer to the OPR and BOD to ensure that no key comfort, health, productivity, daylight, or life-cycle cost concerns are sacrificed.
During the budget estimating phase, the project team may decide to remove some energy-saving strategies that have been identified as high-cost items during the value-engineering process. However, it is very important to help the project team understand that these so-called add-ons are actually integral to the building’s market value and the owner’s goals.
Removing an atrium, for example, due to high cost may provide additional saleable floor area, but may also reduce daylight penetration while increasing the lighting and conditioning loads.
Although this prerequisite is a design-phase submittal, it may make sense to submit it, along with EAc1, after construction. Your project could undergo changes during construction that might compel a new run of the energy model to obtain the latest energy-saving information. Waiting until the completion of construction ensures that the actual designed project is reflected in your energy model.
Create a final energy model based completely on construction document drawings—to confirm actual energy savings as compared to ASHRAE 90.1-2007 requirements. An energy model based on the construction documents phase will provide realistic energy-cost savings and corresponding LEED points likely to be earned.
Make sure the results fit the LEED Online credit form requirements. For example, the unmet load hours have to be less than 300 and process loads will raise a red flag if they’re not approximately 25%. If any of the results are off mark, take time to redo the model. Time spent in design saves more later on in the LEED review process.
Finalize all design decisions and confirm that you’ve met all of the prescriptive requirements. Your team must document the checklist with relevant project drawings, including wall sections, specifications, and the MEP drawing layout.
Value engineering and other factors can result in design changes that eliminate certain energy features relevant to the prerequisite. As this compliance path is prescriptive, your project cannot afford to drop even one prescribed item.
Value engineering and other factors can result in design changes that eliminate certain energy features relevant to the credit. As this compliance path is prescriptive, your project cannot afford to drop even one listed item. Although perceived as high-cost, prescriptive requirements lower energy costs during operation and provide a simple payback structure.
The architect and mechanical engineer review the shop drawings to confirm the installation of the selected systems.
The commissioning agent and the contractor conduct functional testing of all mechanical equipment in accordance with EAp1: Fundamental Commissioning and EAc3: Enhanced Commissioning.
Find your Energy Star rating with EPA’s Target Finder tool if your building type is in the database. Input your project location, size, and number of occupants, computers, and kitchen appliances. The target may be a percentage energy-use reduction compared to a code-compliant building, or “anticipated energy use” data from energy model results. Add information about your fuel use and rate, then click to “View Results.” Your Target Finder score should be documented at LEED Online.
Plan for frequent site visits by the mechanical designer and architect during construction and installation to make sure construction meets the design intent and specifications.
Emphasize team interaction and construction involvement when defining the project scope with key design team members. Contractor and designer meetings can help ensure correct construction practices and avoid high change-order costs for the owner.
Subcontractors may attempt to add a premium during the bidding process for any unusual or unknown materials or practices, so inform your construction bidders of any atypical design systems at the pre-bid meeting.
The energy modeler ensures that any final design changes have been incorporated into the updated model.
Upon finalizing of the design, the responsible party or energy modeler completes the LEED Online submittal with building design inputs and a PRM result energy summary.
Although EAp2 is a design phase submittals, it may make sense to submit it (along with EAc1) after construction. Your project could undergo changes during construction that might require a new run of the energy model. Waiting until the completion of construction ensures that your actual designed project is reflected. On the other hand, it gives you less opportunity to respond to questions that might come up during a LEED review.
Include supporting documents like equipment cut sheets, specifications and equipment schedules to demonstrate all energy efficiency measures claimed in the building.
It common for the LEED reviewers to make requests for more information. Go along with the process—it doesn’t mean that you’ve lost the credit. Provide as much information for LEED Online submittal as requested and possible.
The design team completes the LEED Online documentation, signing off on compliance with the applicable AEDG, and writing the narrative report on the design approach and key highlights.
During LEED submission, the project team needs to make an extra effort to support the prerequisite with the completed checklist and the required documents. Although the LEED rating system does not list detailed documentation, it is best practice to send in supporting documents for the prescriptive requirements from the AEDG. The supporting documents should include relevant narratives, wall sections, mechanical drawings, and calculations.
Although the LEED Online sign-off does not include a checklist of AEDG requirements, it assumes that the team member is confirming compliance with all detailed requirements of the guide.
The design team completes the LEED Online credit form, signing off on compliance with the Core Performance Guide, and writing the narrative report on the design approach and key highlights.
During LEED submission, your project team needs to make an extra effort to support the prerequisite with the completed checklist and the required documents. Although not every requirement may be mentioned in the LEED documentation, the supporting documents need to cover all requirements with narratives, wall sections, mechanical drawings, and calculations.
Many of this option’s compliance documents are common to other LEED credits or design documents, thus reducing duplicated efforts.
Develop an operations manual with input from the design team in collaboration with facility management and commissioning agent if pursuing EAc3: Enhanced Commissioning.
The benefit of designing for energy efficiency is realized only during operations and maintenance. Record energy use to confirm that your project is saving energy as anticipated. If you are not pursuing EAc5: Measurement and Verification, you can implement tracking procedures such as reviewing monthly energy bills or on-the-spot metering.
Some energy efficiency features may require special training for operations and maintenance personnel. For example, cogeneration and building automation systems require commissioning and operator training. Consider employing a trained professional to aid in creating operation manuals for specialty items.
Energy-efficiency measures with a higher first cost often provide large savings in energy use and operational energy bills. These credit requirements are directly tied to the benefits of efficient, low-cost operations.
Excerpted from LEED 2009 for New Construction and Major Renovations
To establish the minimum level of energy efficiency for the proposed building and systems to reduce environmental and economic impacts associated with excessive energy use.
Demonstrate a 10% improvement in the proposed building performance rating for new buildings, or a 5% improvement in the proposed building performance rating for major renovations to existing buildings, compared with the baseline building performanceBaseline building performance is the annual energy cost for a building design, used as a baseline for comparison with above-standard design. rating.
Calculate the baseline building performance rating according to the building performance rating method in Appendix G of ANSI/ASHRAE/IESNA Standard 90.1-2007 (with errata but without addenda1) using a computer simulation model for the whole building project. Projects outside the U.S. may use a USGBC approved equivalent standard2.
Appendix G of Standard 90.1-2007 requires that the energy analysis done for the building performance rating method include all energy costs associated with the building project. To achieve points using this credit, the proposed design must meet the following criteria:
For the purpose of this analysis, process energy is considered to include, but is not limited to, office and general miscellaneous equipment, computers, elevators and escalators,kitchen cooking and refrigeration, laundry washing and drying, lighting exempt from the lighting power allowance (e.g., lighting integral to medical equipment) and other (e.g., waterfall pumps).
Regulated (non-process) energy includes lighting (for the interior, parking garage, surface parking, façade, or building grounds, etc. except as noted above), heating, ventilation and air conditioning (HVAC) (for space heating, space cooling, fans, pumps, toilet exhaust, parking garage ventilation, kitchen hood exhaust, etc.), and service water heating for domestic or space heating purposes.
Process loads must be identical for both the baseline building performance rating and the proposed building performance rating. However, project teams may follow the exceptional calculation method (ANSI/ASHRAE/IESNA Standard 90.1-2007 G2.5) or USGBC approved equivalent to document measures that reduce process loads. Documentation of process load energy savings must include a list of the assumptions made for both the base and the proposed design, and theoretical or empirical information supporting these assumptions.
Projects in California may use Title 24-2005, Part 6 in place of ANSI/ASHRAE/IESNA Standard 90.1-2007 for Option 1.
Comply with the prescriptive measures of the ASHRAE Advanced Energy Design Guide appropriate to the project scope, outlined below. Project teams must comply with all applicable criteria as established in the Advanced Energy Design Guide for the climate zoneOne of five climatically distinct areas, defined by long-term weather conditions which affect the heating and cooling loads in buildings. The zones were determined according to the 45-year average (1931-1975) of the annual heating and cooling degree-days (base 65 degrees Fahrenheit). An individual building was assigned to a climate zone according to the 45-year average annual degree-days for its National Oceanic and Atmospheric Administration (NOAA) Division. in which the building is located. Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone.
The building must meet the following requirements:
Comply with the prescriptive measures identified in the Advanced Buildings™ Core Performance™ Guide developed by the New Buildings Institute. The building must meet the following requirements:
Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone.
1Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.
2 Projects outside the U.S. may use an alternative standard to ANSI/ASHRAE/IESNA Standard 90.1-2007 if it is approved by USGBC as an equivalent standard using the process identified in the LEED 2009 Green Building Design and Construction Global ACP Reference Guide Supplement.
Design the building envelope and systems to meet baseline requirements. Use a computer simulation model to assess the energy performance and identify the most cost-effective energy efficiency measures. Quantify energy performance compared with a baseline building.
If local code has demonstrated quantitative and textual equivalence following, at a minimum, the U.S. Department of Energy (DOE) standard process for commercial energy code determination, then the results of that analysis may be used to correlate local code performance with ANSI/ASHRAE/IESNA Standard 90.1-2007. Details on the DOE process for commercial energy code determination can be found at http://www.energycodes.gov/implement/ determinations_com.stm.
1 Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.
2 Projects outside the U.S. may use an alternative standard to ANSI/ASHRAE/IESNA Standard 90.1‐2007 if it is approved by USGBC as an equivalent standard using the process located at www.usgbc.org/leedisglobal
This database shows state-by-state incentives for energy efficiency, renewable energy, and other green building measures. Included in this database are incentives on demand control ventilation, ERVs, and HRVs.
Useful web resource with information on local/regional incentives for energy-efficiency programs.
ACEEE is a nonprofit organization dedicated to advancing energy efficiency through technical and policy assessments; advising policymakers and program managers; collaborating with businesses, public interest groups, and other organizations; and providing education and outreach through conferences, workshops, and publications.
The New Buildings Institute is a nonprofit, public-benefits corporation dedicated to making buildings better for people and the environment. Its mission is to promote energy efficiency in buildings through technology research, guidelines, and codes.
The Building Energy Codes program provides comprehensive resources for states and code users, including news, compliance software, code comparisons, and the Status of State Energy Codes database. The database includes state energy contacts, code status, code history, DOE grants awarded, and construction data. The program is also updating the COMcheck-EZ compliance tool to include ANSI/ASHRAE/IESNA 90.1–2007. This compliance tool includes the prescriptive path and trade-off compliance methods. The software generates appropriate compliance forms as well.
Research center at RPI provides access to a wide range of daylighting resources, case studies, design tools, reports, publications and more.
International association of energy modelers with various national and local chapters.
Non-profit organization aiming at design community to increase collaboration for designing energy efficient buildings.
The Low Impact Hydropower Institute is a non-profit organization and certification body that establishes criteria against which to judge the environmental impacts of hydropower projects in the United States.
The Building Technologies Program (BTP) provides resources for commercial and residential building components, energy modeling tools, building energy codes, and appliance standards including the Buildings Energy Data Book, High Performance Buildings Database and Software Tools Directory.
This website discusses the step-by-step process for energy modeling.
This online resource, supported by Natural Resources Canada, presents energy-efficient technologies, strategies for commercial buildings, and pertinent case studies.
This website is a comprehensive resource for U.S. Department of Energy information on energy efficiency and renewable energy and provides access to energy links and downloadable documents.
Information on cogenerationThe simultaneous production of electric and thermal energy in on-site, distributed energy systems; typically, waste heat from the electricity generation process is recovered and used to heat, cool, or dehumidify building space. Neither generation of electricity without use of the byproduct heat, nor waste-heat recovery from processes other than electricity generation is included in the definition of cogeneration., also called combined heat and power, is available from EPA through the CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. Partnership. The CHP Partnership is a voluntary program seeking to reduce the environmental impact of power generation by promoting the use of CHP. The Partnership works closely with energy users, the CHP industry, state and local governments, and other clean energy stakeholders to facilitate the development of new projects and to promote their environmental and economic benefits.
Free download of AHSRAE energy savings guide, use for Option 2.
Research warehouse for strategies and case studies of energy efficiency in buildings.
An online window selection tool with performance characteristics.
This website lays out design process for developing an energy efficient building.
This website discusses ways to improve design for lower energy demand as they relate to the AIA 2030 challenge.
This website includes discussion of design issues, materials and assemblies, window design decisions and case studies.
This site lists multiple web-based and downloadable tools that can be used for energy analyses.
This database is maintainted by the California Energy Commission and lists resources related to energy use and efficiency.
Energy design tools are available to be used for free online or available to download.
This website lists performance characteristics for various envelope materials.
This is an online forum of discussion for energy efficiency, computer model software users.
Target Finder is a goal-setting tool that informs your design team about their project’s energy performance as compared to a national database of projects compiled by the EPA.
This directory provides information on 406 building software tools for evaluating energy efficiency, renewable energy, and sustainability in buildings.
Weather data for more than 2100 locations are available in EnergyPlus weather format.
Weather data for U.S. and Non-U.S. locations in BIN format.
A web-based, free content project by IBPSA-USA to develop an online compendium of the domain of Building Energy Modeling (BEM). The intention is to delineate a cohesive body of knowledge for building energy modeling.
A guide for achieving energy efficiency in new commercial buildings, referenced in the LEED energy credits.
This manual is a strategic guide for planning and implementing energy-saving building upgrades. It provides general methods for reviewing and adjusting system control settings, plus procedures for testing and correcting calibration and operation of system components such as sensors, actuators, and controlled devices.
This document is USGBC’s second (v2.0) major release of guidance for district or campus thermal energy in LEED, and is a unified set of guidance comprising the following an update to the original Version 1.0 guidance released May 2008 for LEED v2.x and the initial release of formal guidance for LEED v2009.
This manual offers guidance to building energy modelers, ensuring technically rigorous and credible assessment of energy performance of commercial and multifamily residential buildings. It provides a streamlined process that can be used with various existing modeling software and systems, across a range of programs.
Chapter 19 is titled, “Energy Estimating and Modeling Methods”. The chapter discusses methods for estimating energy use for two purposes: modeling for building and HVAC system design and associated design optimization (forward modeling), and modeling energy use of existing buildings for establishing baselines and calculating retrofit savings (data-driven modeling).
Required reference document for DES systems in LEED energy credits.
ASHRAE writes standards for the purpose of establishing consensus for: 1) methods of test for use in commerce and 2) performance criteria for use as facilitators with which to guide the industry.
Energy statistics from the U.S. government.
This guide includes instructional graphics and superior lighting design solutions for varying types of buildings and spaces, from private offices to big box retail stores.
This website offers information on energy efficiency in buildings, highlighting success stories, breakthrough technology, and policy updates.
Bimonthly publication on case studies and new technologies for energy efficiency in commercial buildings.
AIA publication highlighting local and state green building incentives.
2008 guidelines and performance goals from the National Science and Technology Council.
Information about energy-efficient building practices available in EDR's Design Briefs, Design Guidelines, Case Studies, and Technology Overviews.
DOE tools for whole building analyses, including energy simulation, load calculation, renewable energy, retrofit analysis and green buildings tools.
This is a computer program that predicts the one-dimensional transfer of heat and moisture.
DesignBuilder is a Graphical User Interface to EnergyPlus. DesignBuilder is a complete 3-D graphical design modeling and energy use simulation program providing information on building energy consumption, CO2Carbon dioxide emissions, occupant comfort, daylighting effects, ASHRAE 90.1 and LEED compliance, and more.
IES VE Pro is an integrated computing environment encompassing a wide range of tasks in building design including model building, energy/carbon, solar, light, HVAC, climate, airflow, value/cost and egress.
Use this checklist of prescriptive requirements (with sample filled out) to have an at-a-glance picture of AEDG requirements for Option 2, and how your project is meeting them.
This spreadsheet lists all the requirements for meeting EAp2 – Option 3 and and EAc1 – Option 3. You can review the requirements, assign responsible parties and track status of each requirement through design and construction.
Sometimes the energy simulation software being used to demonstrate compliance with Option 1 doesn't allow you to simulate key aspects of the design. In this situation you'll need to write a short sample narrative, as in these examples, describing the situation and how it was handled.
In your supporting documentation, include spec sheets of equipment described in the Option 1 energy model or Options 2–3 prescriptive paths.
This is a sample building energy performance and cost summary using the Performance Rating Method (PRM). Electricity and natural gas use should be broken down by end uses including space heating, space cooling, lights, task lights, ventilation fans, pumps, and domestic hot water, at the least.
Option 1 calculates savings in annual energy cost, but utility prices may vary over the course of a year. This sample demonstrates how to document varying electricity tariffs.
This graph, for an office building design, shows how five overall strategies were implemented to realize energy savings of 30% below an ASHRAE baseline. (From modeling conducted by Synergy Engineering, PLLC.)
The climate zones shown on this Department of Energy map are relevant to all options for this credit.
This spreadsheet, provided here by 7group, can be used to calculate the fan volume and fan power for Appendix G models submitted for EAp2/EAc1. Tabs are included to cover both ASHRAE 90.1-2004 and 90.1-2007 Appendix G methodologies.
The following links take you to the public, informational versions of the dynamic LEED Online forms for each NC-2009 EA credit. You'll need to fill out the live versions of these forms on LEED Online for each credit you hope to earn.
Version 4 forms (newest):
Version 3 forms:
These links are posted by LEEDuser with USGBC's permission. USGBC has certain usage restrictsions for these forms; for more information, visit LEED Online and click "Sample Forms Download."
Documentation for this credit can be part of a Design Phase submittal.
Model the proposed as designed. It is certainly possible that the proposed fans could use more energy than the baseline fans.
We are working on a hotel project. The guest rooms have a key tagLEED Technical Advisory Group (TAG): Subcommittees that consist of industry experts who assist in developing credit interpretations and technical improvements to the LEED system. system where the lights and AC switches off as soon as the guest removes the key from the key slot. Can we adopt exceptional calculation methodology to claim savings under lighting and HVAC? Base case will be modelled with operating hours 24x7 and proposed case for about 16-18 hours working per day .
See Appendix D4 in the Advanced Energy Modeling Guide for LEED for a methodology that is acceptable for LEED. I do not think that your operating hour assumptions are reasonable.
Do I understand correctly from 90.1 Table G3.1 item 5f for baseline building that I can input the existing envelope conditions in the baseline model in lieu of the 90.1 minimum envelope requirements? My proposed building will be modeled using the design envelope. Thanks.
Yes assuming the space was previously conditioned.
How do you suggest accounting for poor infiltration in the existing/baseline building, when a building envelope project was a part of the renovation which improved/decreased infiltration in the proposed building? We are renovating a historic building which included window replacements, furring out the walls and insulating. We recieved the review comment, "...the infiltration rates must be modeled identically between the baseline and proposed cases. Revise the model, as required, such that the infiltration rates are modeled identically."
The building was leaking like a sieve before the renovation and we modeled it with "poor" tightness (in TRACE) for the baseline. This resulted in the entered values in the TRACE model being 1 ACHAir changes per hour: The number of times per hour a volume of air, equivalent to the volume of space, enters that space. in the baseline and 0 ACH in the proposed. How should we alternatively model this to account for the improvement in infiltration between the old/existing building and the new/proposed building? I appreciate any advice!
Under the current rules you cannot claim any credit for reduced infiltration. The problem is that there is not a defined baseline of performance.
Your comparison assumptions are a case in point. What was your basis for 1 ACHAir changes per hour: The number of times per hour a volume of air, equivalent to the volume of space, enters that space.? Was it measured? The proposed 0 ACH is frankly not possible. If you want to try and claim savings for infiltration you will need to present an ironclad case, as an exceptional calculation, for it based on actual pre and post measurements in my opinion. That may work for an existing building but still potentially raises many baseline questions regarding the existing conditions.
I don't believe there is a set approach as to how the proposed building average infiltration should be calculated? In my experience in heating led climates I have always used conversions from the air pressure test (m3/hr/m2 at 50Pa) to average ACH based on the building type and stories. Typically for a value of 10m3/hr/m2 at50 Pa this may be 0.15-0.25ACH
However I have read that when the building is positively pressurized the infiltration is likely to reduce but not to zero but there doesn't seem to be a standard to what. I have read 10% (which basically is almost zero at low air tightness).
I was wondering what others approach was?
I have read some research that indicated that infiltration is a much larger component of energy use than previously thought. The lack of infiltration in positively pressurized buildings is basically a myth. I think NREL did some of this research and I know there have been some ASHRAE Journal articles.
Also the UK has specific standards for air tightness and requires testing in certain buildings I think. Good links and information on this web site - http://www.infiltec.com/inf-larg.htm
We are currently working on a school project targeting <0.10 cfm/square foot @ 50 pa.
How is ASHRAE 22.214.171.124.2 5 degree deadband interpreted? 70-75 deadband provides six temperatures in which the thermostat is "dead". 70-74 deadband provides 5 temperatures in which the thermostat is "dead".
Also, has anyone received a comment from a LEED reviewer stating that ASHRAE 126.96.36.199.2 was not accurately modeled?
75 minus 70 = 5
This issue is not something that the reviewer typically looks for in the modeling inputs. Since the temperature settings must be the same in both models (which the reviewers do check on if the input summary reports contain that information), modeling something less than 5 degrees would have no real impact on the relative energy use. So I am not aware of this being an issue within a LEED review but it certainly could be since it is a mandatory provision.
automatic daylighting controls and occupancy sensor are adapted into the project, and many other energy saving measures included,i do not simulate daylighting control and occupancy sensor in the energy model for the first submittal, because my project requirement is just 10% cost saving and i achieved 14.3% cost saving by other energy efficiency strategies.
the reviewer comments require that i provide a narrative describing the controls and how they are implemented in the Proposed energy
model. can i answer " i did not model automatic daylighting controls and occupancy sensor in the energy model based on my project certification goal?
You are required by Appendix G to model the project as designed which includes all of the strategies in the design (Table G3.1-1). Your percent savings goal really has nothing to do with the issue so I would not even bring it up.
Even though you are required to model the project as designed/constructed, you are permitted to exclude certain design features if you can demonstrate that not modeling them results in a conservative estimate of savings. In other words you are just hurting your savings so that is typically allowed.
So I would just explain the the reviewer the lighting controls and how they were modeled. Make sure you have properly addressed any control issues which are also mandatory provisions (like 188.8.131.52) as these are required no matter your percent savings.
I looked thru all 2000+ comments and didn't see this addressed.
I have a hotel project with a pool, fitness room, vending/ice machines, ect. The owner doesn't want these spaces to ever be dark. Some spaces like the fitness room are available 24/7 and they want it to be inviting even when not in use. They'd like 1/3 of the lights on 24/7 and the remaing on an occupancy sensor.
I don't think this meets the requirements of ASHRAE 90.1 that all lighting have automatic shut off. I know there is an exception for spaces intended for 24 hour operation. I am using this exception for the Hotel lobby and corridors lights. The User's Manual for 90.1-2007 says, "The Standard does not require automatic shutoff for spaces intended for 24-hour operation."
This sounds simple but has a very large gray area. I'm looking for opinions from others. Where is the cutoff on what 24-hour operation means? In use? Available for use?
There is a large glass wall between the rooms and the corridor. People assume a dark room means the space is closed. I want to meet ASHRAE but also meet a client's needs. Thanks.
Turn off the lights but put an LED "open" sign by the door.
For LEED you basically get to define the schedules so you can define the 24 hour spaces. I do not see a problem for LEED in setting up the lights in this area like you have outlined beyond the obvious wasted energy.
We are working on a residential project where the HVAC system won´t be provided for the apartments, the project scope contemplates the preparation and space for the equipments so every owner can install his own equipment (probably mini splits).
The question is, should we model the baseline and the proposed system the same? since we don´t know if the 100% of the apartments will have air conditioned or the characteristics of the equipments that will be installed. And another issue we are having with this prerequisite is that the envelope considers an 80% of glassing while ASHRAE only considers a 40% maximum, therefore it will be very difficult to accomplish this prerequisite because the HVAC system won´t accomplish any savings and the glassing is above the baseline percentage.
Is there an alternative way for these kind of cases where the original scope is not defined yet, but it will be defined later until the operation of the building?
Or, can we apply as Core and Shell instead of New Construction? even if the apartments will be sold instead of rented.
Thank you in advance.
Sounds like core and shell to me. The two issues you raise will certainly make it difficult to meet the minimum. You could also add almost no lighting savings available either. You are going to need some pretty fantastic glass!
If there no HVAC design in the units the system is modeled identically to the baseline system (see Table G3.1-10).
There is a reason the standard limits the glass to wall ratio as this is a very wasteful practice and projects should pay a penalty if they still wish to do so.
Thanks for you answer, Marcus. The owner will definitely have to install a pretty efficient glass in order to comply, even more so with the high glazing ratio.
Is it C&S even though the developer is going to habilitate everything except HVAC (which, as before mentioned, will be preparations for it to be installed by each occupant)? Lighting, furniture, furnishings, water equipment, etc., are inside the scope. Is it valid to pursue NC and in order to claim savings on HVAC to present each apt. owner with the HVAC specifications?
And another couple of questions: we have another residential apartment building that will have no HVAC in the apartments. (The location's climate is quite benevolent) Then the energy savings will depend on lighting, the couple of areas (amenities) with HVAC, and electrical equipment, is this true? The developer will habilitate everything: is it correct to pursue NC?
Now it is sounding more like NC. I assumed that if the HVAC was not being installed then much of the rest of the interior fit out would not be included either. How many floors is the project? Maybe LEED Mid-Rise Residential applies?
Sounds right. The apartments would be considered unconditioned space.
The project has 8 or 9 floors at the most.
Is LEED Mid-Rise Residential available for projects outside the US (Mexico)?
Thanks for your feedback!
That might be stretching it a bit. I know the Mid-Rise folks have been trying to stretch it but at one point it was limited to 4 to 6 stories. Not sure what the current limit is however and USGBC's web site is currently having issues. I think all the rating system are available for use outside the US.
Our project is at South East Asia, do we need to comply to ASHRAE 90.1 on electric shower?
Do you mean an instantaneous water heater? If so that is covered by 90.1.
thanks Marcus, somehow over here, we unable to get any instantaneous water heater aka home electrical heater with Energy Star label (whom i believe , tested under DOE 10CFR 430).
we might able to find electrical heater with local energy efficient rated product. do you think this gbci will accept this?
Commercially is expensive to ship few units of such from US to here, and yet to mention, local has it own energy efficient product too. Thought?
The water heater you use does not have to be Energy Star. It does need to meet the minimum efficiency from Table 7.8 but it does not appear that an electric instantaneous is covered in this table so it would be exempt from any minimum efficiency.
Fact or Fiction: For EAp2 ASHRAE 90.1 §184.108.40.206.1 all mechanical Equipment must have a Label installed by the manufacturer stating that the equipment complies with the requirements of Standard 90.1 even in countries outside even of the US?
Background : We have a project outside of the US where the mechanical equipment is not covered by the U.S. National Appliance Energy Conservation ACT of 1987 and suppliers normally do not put on the 1987 equivalency label. We are working with 2014 European standards. So what should we do? How can we show Construction Stage compliance?
Can we meet this requirement if the mechanical equipment manufacturers put on the EU current standard? Or is getting the HVAC design team to electronically sign the LEED ONLINE check box sufficient?
For LEED this mandatory provision for projects outside the US would not be required.
We are working on a single building certification that is located within a two tower project. I will call the building to be certified Tower 1 and the building located to the south Tower 2. Tower 1 will be part of the first development phase, Tower 2 located south of Tower 1 could help us in terms of creating shadow to our building, and thus reducing direct sunlight to our project, but it is considered in another phase 5 years after completion of Tower 1.
The question is: Can we model Tower 2, and thus document it as a shadowing element that will help reduce cooling loads considering it will be built after five years of tower 1 completion?
ASHRAE 90.1-2010 Table G3.1-14 should be used to guide the modeling of the surroundings. In terms of your situation I do not think that you would be allowed to model something that was not already in place.
Thank you for your comment. Table G3.1-14 of ASHRAE 90.1-2010 does not mention anything about future adjacent structures that could create shading effects. In my opinion, for this particular case, the second tower is planned to be constructed in a short period of time after the first one, so it should be taken into account in the energy modeling, considering the life-time of the buildings and the significant shading effect it will create. Another issue is that the sizing of the HVAC system must be done without considering the second tower, but once it is built then the system will be oversized.
Have you heard cases like this one before?
I think it does not mention it because things that "might" be built in the future cannot be assured of actually being built and logically should not be taken into account. You bring up a good point about the system sizing. If you are sizing the HVAC without the second tower it sounds like the designers are not too sure it will happen or it will be too long between construction to account for it.
In general projects receive credit for what they actually do. In some cases they get credit for what they do in response to a preexisting situation. They usually do not get credit for something that might happen in the future.
The second tower is part of the project, there are actually four towers in total in the whole plan within the site. If we would be able to make the client prove that it will be built within a short period of time, do you think we could include it?
About the system sizing I think that it has to be done without considering the 2nd tower even if is 100% sure it will be built, otherwise during the construction of it there will be a lot of thermal comfort problems.
My previous response was based on what I think the ASHARE Appendix G reason would be for including the second tower or not. I do not think that under Appendix G it should be included.
In my opinion it will not make much difference for LEED if you model it. If you did include it you would have to do so for the baseline as well, so the effect on the savings is minimal. If you did include it in both models I think the reviewer would probably not make you take it out.
I know that I can take credit for automatic daylighting controls under the Performance Rating Method of Appendix G. However, can I take credit for them for code compliance purposes under the Energy Cost Budget (ECB) method?
I don't see why not.
I have two questions regarding the inclusion of UPS in the 'Energy Star' calculation in LEED v2009.
Q1. The LEEDv2009 Reference Guide language says... "Any category added to ENERGY STAR list in the future may be used in the project team's calculation".
Since UPS was added as a new category in 2013... it would seem reasonable to NOT include UPS in the calculation if the project team decides to do so. Is that correct?
Q2. Notwithstanding the above... IF it is now required to include the UPS in the Energy Star calculation... what is the correct 'Rated PowerRated power is the nameplate power on a piece of equipment. It represents the capacity of the unit and is the maximum that it will draw.' for inclusion in the LEED Online table?
The UPS mostly stands idle... but (potentially) has a huge 'Output Rated Power' say 200,000 Watts for a short period of time from the battery back-up power.
While the maximum power drawn by the UPS is a much lower number... say 2,000 Watts!
My understanding is that we would use the maximum draw power of the UPS (say 2,000Watts) rather than the maximum power output (say 200,000 Watts) of the UPS that we would input to the Energy Star calculation. Is that correct?
Thanks in advance... Any advice is much appreciated.
I think you have posted this question in the wrong forum. Looks like it should be in CI EAc1.4 I think.
Opps!... My mistake!
I've re-posted in CI EAc1.4.
We have a very critical problem for a LEED C&S 2009 project located in the north of Mexico. The project will be a 13th story office building. Based on Appendix G the baseline HVAC system corresponds to 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, using a water-cooled chiller system. The main problem here is that for the location of the project the water resource is very limited, also the quality is very bad, so installing water-cooled chillers is not a viable option. Instead what is very common is to install air-cooled chillers. So when comparing the performance of the baseline model against the proposed design, of course we cannot achieve a better performance because the efficiencies of a water-cooled chiller are much higher than the ones of an air-cooled chiller. In conclusion, it will be very hard to comply with EAp2. Is there some kind of alternative compliance path based on the fact that for this particular location water is very limited and expensive?
Hopefully there is, otherwise I doubt we will be able to achieve the certification.
One consideration the GBCI has made for C&S projects, that you may have considered, but just in case you did not, is utilizing the Alternative Compliance Path for C&S 2009. It utilizes a spreadsheet to revise the points threshold depending on the Developer influenced energy cost.
I am not sure how much it will help in your case, but anything might help you get through to above the pre-req to compensate for a bad envelope.
In case you can't find it, here is the document
Thanks for tip but we have already consider this ACP.
Make the building smaller? :-)
I am afraid you are stuck with Appendix G.
I have a question regarding an HVAC baseline model for systems 7 and 8.
We have a project located in a very arid zone, where water is very limited. The project is contemplating a water chilled system with an air cooled chiller.
We are doing an energy model, and according to ASHRAE 90.1 2007, in Appendix G, we must model the baseline as a water cooled chiller. Air cooled and water cooled chillers have very different efficiencies, and so far the results have shown that in no way will we be able to come close to demonstrating 10% in savings. (the whole building is 100% glass, we’ve tried having a reasonably priced but very efficient glass, lowered the LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space., used controls.. etc.)
My question is, what can we do? Could we model the baseline chiller as an air cooled one? Could we use an alternative compliance path? Asking the client to install cooling towers, given the limited water situation seems a bit unreasonable. Have you ever had this kind of situation in a project? How do air cooled chillers demonstrate compliance?
I have done various e-models in Mexico in different climate zones. And yes air-cooled chillers are used extensively. They can also tend to be more economical to operate.
I have found that utilizing an air-cooled chiller with primary-variable pumping system are more efficient overall than the ASHRAE baseline with a chiller, primary-constant/secondary-variable pumping, and cooling towers w/CDW pumps. The saving is generated by the reduced pumping, which offsets the lower efficiency of the compressors compared to water-cooled. You can also equate the additional reduced pumping, since you do not have to pump water from the basement to the roof for the cooling tower (MAKE-UP WATER), this is not a small amount of water and/or pumping energy.
By the way, the owner ends up saving money on the initial installed equipment also, and reduced water usage fees.
THERE IS NO OTHER WAY TO CALCULATE THIS, YOU ONLY HAVE APPENDIX G AS YOUR OPTION.
1) I get downright annoyed when I hear of architects building glass houses. It's a bad idea in almost all climates. Both user comfort and energy savings suffer...for many reasons. Thank goodness there are systems like LEED now that will force them to reconsider.
2) the above point on chiller performance is well made. Because chillers are often oversized and running everywhere except at full load, the comparitive energy usage lay in the mostly unintelligable partload performance matrix consisting of a marad of parameters. The two chiller systems may be much closer than you think.
In your situation I would say that the main problem on achieving 10% savings does not lay with the chiller type, it's the glass. And now you're left trying to "pollish the turd" as they say in Manchester.
We do achieve high energy savings in pump energy but this is corresponds to a very low percentage of the total energy consumption of the building, where as the cooling energy represents around 40%. So in this particular case there is no way to achieve a better overall performance when using an air-cooled chiller. The main problem as Jean says is the % of glass, but even with the same % of glass as the baseline design it is difficult to comply with the pre-requisite.
We are in the process of responding to the comments we received from the reviewers on the energy model of one of our project performed with eQuest.
The reviewer is asking us to provide an input report showing that the minimum air flow rates for 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. systems in our baseline model were modeled correctly. (ASHRAE 90.1-2007 Section
G220.127.116.11 requires that the minimum volume 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. for the VAV reheat terminal units are modeled at 0.4 cfm per square feet, unless
this reduces the outside air rate below the minimum value.)
We don't seem to find any input reports showing clearly the min airflowrates in CFM/SF. Do you know any eQuest input reports that could be provided to the reviewers?
in the Air Side HVAC section you can probably do a screen shot of either the spreadsheet TAB or the summary TAB.
It has worked for me in the past
if you want to provide the DOE documents give them SV-A, it summarizes the MIN-FLOW per zone
You should combine the spreadsheet tab screen capture with a narrative explanation of how you have incorporated this into your model since the 0.4 is not a direct input.
We are in the process of doing Energy Simulation for Garments Factory. We have completed the base case part and proposed case is pending. So that we have received the all necessary details such as LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space., EPD, Specification of Envelopes, etc...
From the specification of envelopes, we have observed that they have not mentioned the U Value, SHGCSolar heat gain coefficient (SHGC): The fraction of solar gain admitted through a window, expressed as a number between 0 and 1.. They have mentioned the following specifications only.
3. Sp. Heat
5. Hatch - Defines the displayed hatch pattern of the layer.
We need the specified values for U value and SHGC.
Is it possible to calculate U value and SHGC from the above specifications? (Point No 1 to 5)
If possible, I would like to know the method to calculate the same.
I need your help please..
Note: Multi layers are used in the building envelopes.
ASHRAE Standard 90.1-2007 App. A is your new best friend. Get to know her very well. It also tells you what to do if your envelope componant does not fit any of the available constructions and which are the best guidelines to use if user calculating values (which is a pretty intensive excersize, so try to avoid that if possible).
You can typically get the SHGCSolar heat gain coefficient (SHGC): The fraction of solar gain admitted through a window, expressed as a number between 0 and 1. from the glazing or window manufacturer.
One part of your post struck me. You did the baseline before the proposed? In general this is backward as many items in the baseline are dependent on the proposed. Perhaps you should try it the other way around next time.
I remember ASHRAE 90.1-2007 Users' Manual provides guides on how to calculate U-values (U-factors). SHGCSolar heat gain coefficient (SHGC): The fraction of solar gain admitted through a window, expressed as a number between 0 and 1. might not be easy to calculate unless you have very detailed property data of glazing(s).
You are allowed to use the default values from Table A8.2. In a factory with high process loads the windows may not have much of an effect on energy use and perhaps using these defaults will not adversely affect the results too much.
It is required to factor in the initial equipment installation costs when calculating the annual cost for on-site renewable energy for a proposed building? For a PV system, the initial costs are quite high, but the annual cost for the energy produced is near zero.
The "annual cost" is really the avoided annual energy cost, so no you do not include the initial equipment costs. So if a PV system produces 1000 kWhA kilowatt-hour is a unit of work or energy, measured as 1 kilowatt (1,000 watts) of power expended for 1 hour. One kWh is equivalent to 3,412 Btu. per year then you multiply that times the virtual electric rate to determine the annual cost.
So the calculated virtual electric rate for a building using total of 10,000 kwhA kilowatt-hour is a unit of work or energy, measured as 1 kilowatt (1,000 watts) of power expended for 1 hour. One kWh is equivalent to 3,412 Btu. total would be:
From Utility Company: 9,000 kwh at $0.25/kwh = $2250.
From PV: 1,000 kwh at $0.00/kwh = $0
Virtual rate: $2250/10,000 kwh = $0.225 per kwh
Is this correct?
Building consumption (not accounting for the PV) is 10,000 kWhA kilowatt-hour is a unit of work or energy, measured as 1 kilowatt (1,000 watts) of power expended for 1 hour. One kWh is equivalent to 3,412 Btu. and electric cost without the PV is $2500. Virtual rate is $0.25/kWh.
Virtual rate times 1000 kWh produced by PV equals a $250 renewable contribution.
Thanks for the clarification.
We have a project where our resort rooms will be using spray foam insulation above a concrete slab, set in zone 1. Our rooms are actually small villas. The villas have bayA bay is a component of a standard, rectilinear building design. It is the open area defined by a building element such as columns or a window. Typically, there are multiple identical bays in succession. windows with a separate small roof structure, part of which is in air conditioned interior space. ASHRAE 90.1 Table 5.5-1 calls for R-3.5 (S.I.) "continuous insulation".
Does this still fit the definition of continuous insulation even though most is above and some is below in the bay window area? Is this a concern if one is using Option 1 energy modeling for meeting this LEED prerequisite?
I can't tell if your situation is continuous or not based on your description. Continuous means without any break or gap.
The baseline is always modeled as continuous, consistent insulation.
The proposed gets modeled as designed. See Table G3.1-5 Proposed for the allowable exceptions.
The insulation provisions are not mandatory so you are not required to provide continuous insulation for LEED as this strategy is available for trade-off.
If you have a multi-family building with curtain walls can it still meet the requirements for the energy model? How should the baseline be done?
Yes it can still meet the 10% savings requirement. The baseline is limited to 40% window to wall ratio. So if the proposed is greater than that you typically pay a penalty.
The baseline is always according to Appendix G for any building type.
bathrooms can have a manual shutdown device for lighting?
It is mandatory that all toilets automatically switch off the lighting?
Referencing ASHRAE 90.1-2010, restrooms (similarly for corridors, elec/mech rooms, public lobbies, stairways, and storage rooms) are exempted from auto-off.
Under 90.1-2007 bathrooms must have a manual switch and are not required to have automatic switching according to Section 18.104.22.168.
Thanks Marcus and Gavin!
My proposed design has multiple AHUs supplied from a dedicated outside air AHU (DOAS) . The DOAS will be over 20,000 cfm and will have energy recovery. The baseline system will be Packaged VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. System 5. Should the baseline system be provided with a DOAS with energy recovery, or is each baseline system considered independant, in which case energy recovery will not be required since each unit will have less than 70 percent OA? Thank you, Craig
The key is to keep the ODA min amounts the same in both baseline and designcase models. With DOAS the designcase usually dictates the minimum amount of ODA required zone wise. This same requirement falls to the baseline case.
The baseline case is not modeled as a DOAS system, but you may find that for some zones there may be little or no recirculation air as the ODA amounts may be far more than the required minimums of ASHRAE 62.1.
It does present some trouble. I suggest making a table with the ODA fractions for the zones at design conditions, because if you have a zone that requires little or no ODA, but does require air for conditioning, it may receive too much ODA as the ODA fraction is set at the central 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. ODA mixing damper to accommidate all the connected zone ODA requirements which may be zone volume flow weighted. Like zones should be grouped. You may need to take a closer look at G3.1.1 Exceptions.
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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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