EAc1: Optimize Energy Performance is, by far, the most important credit in LEED, based on the number of points available. Up to 10 points are at stake here based on how much you’re able to reduce the project’s predicted energy cost. That large amount of points also reflects the great importance LEED places on reducing energy use and forestalling climate change1. Climate change refers to any significant change in measures of climate (such as temperature, precipitation, or wind) lasting for an extended period (decades or longer). (U.S. Environmental Protection Agency, 2008)
2.The increase in global average temperatures being caused by a buildup of CO2 and other greenhouse gases in the atmosphere. This temperature change is leading to changes in circulation patterns in the air and in the oceans, which are affecting climates differently in different places. Among the predicted effects are a significant cooling in Western Europe due to changes in the jet stream, and rising sea levels due to the melting of polar ice and glaciers..
You’ll need to choose your approach. For certain buildings types you can opt to skip the energy modeling option and simply follow a list of prescriptive requirements, but you can’t earn nearly as many points that way, and you won’t have the benefit of the energy simulation to guide you to the most cost-effective energy efficiency measures.
This credit is documented in concert with EAp2: Minimum Energy Performance.
An energy-efficient building can cost more to build, through components like efficient mechanical equipment and high-performance glazing. On the other hand, those same higher-cost measures can generate construction-cost savings by reducing the size of mechanical systems. And of course, dramatic financial savings can come during the operational phase. Energy modeling can help determine the “sweet spot” for your project.
Your project may also qualify for financial incentives offered by utilities or local, state, and federal authorities, that help offset the premiums of system upgrades and renewable energy implementation. In many states, utilities or other local entities provide financial incentives in the form of rebates or tax breaks to alleviate the cost premiums associated with installing systems and purchasing equipment geared toward energy efficiency. (See Resources for incentives.)
The LEED Reference guide gives three options, but per USGBC addenda, an additional compliance option has been added to EAc1 for projects registered after June 26, 2007. Documentation for this credit happens along with documentation for the associated prerequisite, EAp2: Minimum Energy Performance. In fact, for the prescriptive options, all you have to do is document the credit—and use the same documents for EAp2.
All four of the following options are available to projects registered before June 26, 2007. Option 1, 2 or 3 must be used for projects registered after June 26, 2007. (These compliance options meet the two-point prerequisite requirement for projects registered after June 2007).
Option 1 offers the potential to earn the maximum number of points available for this credit. This requires whole building energy simulation using a computer model. Your project must reduce energy cost by a minimum of 14% (7% for an existing building) to meet the prerequisite, EAp2, which will also earn your project two points. Under EAc1 you can earn one point for each additional 3.5% of energy cost reduction from the referenced standard (see the table in the credit language for exact amounts). The energy modeling and documentation process is identical for EAp2 and EAc1, Option 1. The exact reduction is established when you run your energy model.
The Advanced Energy Design Guides is published by ASHRAE for office occupancy projects less than 20,000 ft2—so if you don’t fall into that category, you’re not eligible for this path.
This guide outlines strategies to reduce energy use by 30% from 2001 levels, or an amount equivalent to approximately 10%–14% reduction from ASHRAE 90.1-2004. If you choose this compliance path, become familiar with the list of prescriptive requirements and commit to meeting all of them.
Option 3: Compliance with the prescriptive measures of the Core Performance Guide (formerly the Advanced Buildings Benchmark Program) offers an opportunity for a maximum of 5 points. Projects must comply with Section 1 & 2 of the Core Performance Guide. An additional point is available for meeting any three additional requirements, of Section 3 of the Core Performance Guide (CPG). These requirements range from installing a renewable energy system to adding filters to air-handling systems. Review these requirements with your team to select the three or six that are most applicable to your project.
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.
It’s important to note that this path is not just a list of prescriptive requirements, but a prescribed process for achieving energy efficiency goals. Follow the design process from day one after assembling your team. Most of the requirements are difficult to demonstrate for documentation purposes if you didn’t accomplish them at the right stage. You must demonstrate that you considered a couple of alternate designs, for example, and that certain team meetings were held.)
Option 4 option earns one point and is available to only those projects registered before June 26, 2007. Follow Advanced Buildings Benchmark v1.1, Basic Criteria and Prescriptive Measures of the Advanced Buildings Benchmark Version 1.1 as described in LEED-NC v2.2 Reference Guide.
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.
With clearly defined goals and committed team members, your project should be able to achieve an energy cost reduction of 14% to 17.5%, through measures such as the following.
If you want to aim for higher targets of 20%–50% energy savings or higher, consider measures such as the following.
The most cost-effective measures vary by building type and location—refer to ASHRAE Advanced Energy Design Guides and case studies for examples of strategies in your building. (See Resources.)
Building energy performance is a result of interactions between various different building components and systems. The mechanical system consumes energy based on factors such as architectural design, operating schedules, programming and climate. To significantly reduce energy it is very important for all team members to share design ideas and collaborate on strategies. The integrated design process will support constant communication, fast response on new ideas, and can help eliminate misunderstandings or assumptions—consider using it as a central strategy to earning points for this credit.
If your project is connected to a district energy system, LEED-NC v2.2 lets you take advantage of improved system efficiencies. Although not permitted for use with EAp2 (up to 14% energy use reduction has to be demonstrated without inclusion of the district system), you may include the improved efficiency over baseline of the district energy system in the energy model you develop for EAc1. In this scenario, you develop a separate model from the one for EAp2 compliance. (See Resources for more details through the updated guidelines.)
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.)
Begin by identifying a target for energy performance by researching similar building types using the EPA Target Finder program. An Energy Star score of 80 or higher will typically earn EAc1 points.
To earn points for EAc1 you’ll most likely have to significantly exceed your local energy code. Achieving this energy reduction requires special attention to detail by your entire team from the beginning of the design process, and dedicated leadership from the owner.
Note that energy efficiency is not just about efficient boilers and chillers. To achieve high targets, the design of the building has to help reduce dependence on mechanical heating and cooling throughout the year, through measures like orientation, moderate glazing areas, and self-shading.
An automated building management system (BMS) can significantly reduce building energy use by turning down air conditioning and turning off lights during unoccupied hours, along with other similar measures. Occupancy sensors, timers, and temperature sensors feed into the system to switch off lights and fans when not needed. Note that controls can be counted towards energy reductions only through energy modeling.
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 offers the most points, but it requires estimating the energy use of the whole building over a calendar year, using methodology established by ASHRAE 90.1-2004, 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 14% (7% for an existing building), compared to a baseline building with the same form and design but using systems compliant with ASHRAE 90.1-2004. You can earn additional LEED points through EAc1 for cost reductions in 3.5% increments, beyond 14%.
Option 2: Prescriptive Compliance Path: ASHRAE Advanced Energy Design Guide for Small Office Buildings 2004 refers to design guides published by ASHRAE for office projects of 20,000 ft2 of less. 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 90.1-2004 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.)
Complying with Option 2 earns 4 points, and with Option 3, 2-5 points and Option 4, 1 point. If you are committed to greatly reducing energy usage and earning a higher number of points, then follow Option 1 for compliance with both EAp2 and EAc1.
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.)
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 and documentation commitment, which means higher upfront costs.
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 Owner’s Project Requirements (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 in North America, 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 submittal template, and develop the compliance document.
If you are earning two points at 14%, the first round of the model should aim for a minimum 16%–17% cost savings. There may be reduction with changing design or modeling mechanism. Also remember the energy cost savings typically involve the building systems and assume 25% process loads fixed between design and baseline.
Under Option 3 for compliance with the Core Performance Guide, you can earn 2–5 points. It’s a good option if your project is smaller than 100,000 ft2, is not health care, warehouse or laboratory and you’d rather not commit to energy modeling (Option 1).
Some energy conservation measures, such as energy recovery ventilation or a highly insulated building envelope, add to both construction and design costs, though with an integrated design process these costs might be recouped through savings elsewhere, such as through reducing the size of the mechanical system. The most effective approach is to have your building owner and design team together evaluate both the first costs of the energy-saving measures and their effectiveness at reducing operating costs.
The architect, mechanical engineer, and lighting designer need to familiarize themselves and confirm compliance with the mandatory requirements of ASHRAE 90.1-2004, 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.
For existing buildings, the baseline energy model can reflect the pre-renovation features 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 90.1-2004, 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 2004, 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:
Regulated loads. Most prominent systems—space heating, cooling, ventilation and pumps, lighting, and hot water—are regulated by ASHRAE and LEED so are termed “regulated” loads. Your energy model can provide insights into the energy use of all these systems.
Non-regulated loads are those which are not directly associated with creating a comfortable environment, but with plug loads for machines. These include elevators, kitchen equipment, office equipment, televisions, and activity-oriented lighting, such as in hospitals. Though these are very large energy loads, they are not regulated by ASHRAE 90.1 or by LEED. Energy savings from specifying better equipment is not counted in energy models. It is typically expected that these non-regulated loads contribute to 25% of energy use.
The energy model itself will not account for any change in plug loads from the baseline case, even if your project is making a conscious effort to purchase Energy Star or other efficient equipment. Any improvement made in plug loads must be documented separately, using the exceptional calculation methodology (ECM), as described in ASHRAE 90.1-2004. These calculations determine the design case energy cost compared to the baseline case. They are included in the performance rating method (PRM) table or directly in the baseline and design case model.
Besides energy modeling, you may need to use the exceptional calculation methodology (ECM) when any of the following situations occur:
The energy software cannot carry out calculations for a specific system like natural ventilation or unusual HVAC equipment.
Process loads are different in baseline and design cases and can influence total energy cost savings.
The proposed design can’t demonstrate savings with the modeling protocol and needs additional calculations.
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 EQc8.1: Daylight and Views—Daylight can greatly reduce the cost of your modeling efforts.
The model you need to develop for EAc1 is the same as for EAp2 unless you’re on a district energy system. In that case, projects must show that the building can meet the prerequisite (14% reduction for new buildings) by
itself, without the efficiencies of the district plant.
Follow the guidelines on identifying energy-efficiency strategies to achieve the owner’s energy efficiency goals per the Owner’s Project Requirements, developed for EAp1: Fundamental Commissioning.
Your mechanical engineer and energy modeler need to work in collaboration with the architect when finalizing building form, façade treatment, and programming—to give real-time input on the energy impact of all the design features.
Consider highly efficient systems like heat pumps for heating and cooling, district energy and cogeneration, ice storage for off-peak cooling, or energy recovery ventilation—to attain a substantial energy reduction of 10%-20%.
Energy-efficient design can increase your construction budget. Use your computer model to optimize packages of upgrades that balance any added costs against cost savings, and run payback analyses to identify the most cost-effective options.
Even if you’re using Option 1, refer to the Advanced Energy Design Guides and Core Performance Guide (referenced by Options 2 and 3) for ideas on cost-effective measures to implement.
Provide a copy of the AEDG 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.
Make sure you document the early design requirements as they take place. Going back for documentation later is not helpful and very time consuming for the team.
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, EQp1: Minimum Indoor Air Quality Performance, and EQc6.1: Controllability of Systems—Lighting Controls.
This compliance path is top-heavy due to up-front 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.
If you are installing a renewable energy system that provides at least 5% of your electricity, you already implemented one of the three strategies from the Core Performance Guide.
Select those strategies that are most suitable for your project type and location. For example, evaporative cooling is very effective in a hot, dry climate but is not likely to be a good idea in the cooler, damper Northeast or Northwest. The list is a good summary of the best ways to reduce energy intensity, though some strategies may be more effective in offices and museums, while others are more helpful in hospitals and hotels.
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.
Develop multiple iterations of your project design to analyze the energy impact of each change.
Further develop energy optimization strategies with the design team. Look at reducing loads while creating a comfortable environment within the shell. Look at reducing east and west exposures, and at providing south windows with exterior shades to make a design feature out of passive techniques. Discuss highly efficient system design at this stage, before your design is finalized—for example:
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 90.1-2004. 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 90.1-2004-compliant baseline model. The percentage should be at least 14% (or 7% for existing buildings) 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 90.1-2004, 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 14% 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.
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 14% savings threshold.
The baseline model is the designed building with mechanical systems specified in ASHRAE 90.1-2004, 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 14% lower than the baseline in new construction (or 7% 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 construction details of 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 90.1-2004. 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 ASHRAE Advanced Energy Design Guide for Small Offices 2004.
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 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 submittal template 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.
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 on 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. Plan to provide documentation 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.
One complete run of your energy model should be completed during design development to make sure the design is reducing annual energy cost by your targeted amount. This is the time when simplified models used to inform early design decisions should be replaced by a more comprehensive detailed model. Run two or three alternatives to help the designers finalize envelope and system selection. Common measures to consider include high-performance windows, additional roof insulation, and more efficient boilers.
Use your energy model to review envelope thermal and hygrothermal performance. In a heating climate, thick insulation inside the air barrier may cause condensation problems. Consider an exterior thermal barrier to protect the air barrier and to prevent condensation inside the wall cavity. Identify thermal bridges in the walls and windows that could leak heat from inside. Add thermal breaks, such as neoprene gaskets, on shelf angles, silicone beading on window frames, and use other techniques to prevent leakage from the envelope.
Your energy model can be a supportive design tool that provides insight into the actual performance of the building envelope and mechanical systems. It can highlight surprising results, such as a prominent feature like an efficient boiler contributing only a 1% reduction in energy cost. It can also provide evidence to support operational energy-use decisions such as changing the heating or cooling set points a few degrees.
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 WEc3) 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 Guide (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 submittal template does not require detailed documentation for each Core Performance Guide requirement, it is important that each item be documented 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 that can be pursued for the project.
Make sure the identified measures are being implemented. For Section 3 items, check with the mechanical engineer on the status of each measure. Document the measures if they are completed, like daylight control locations and quantities and economizer performance.
Finalize the design, including all energy system strategies. Make sure your project is on track for the target rating based on energy cost.
Assess your compliance with the credit and projected points to be earned. This credit and option can be the largest contributor to your LEED point total, so if you aren’t hitting your goal, consider last minute design changes now.
Specify and contract for efficiency measures. Often new equipment and novel systems are unknown to contractors, so hold bid and construction meetings to ensure your specifications are understood and everything is purchased and installed as intended.
The more thorough your drawings and specifications are, the less the chances of incorrect installation.
Contracting with a commissioning agent for the expanded scope of EAc3: Enhanced Commissioning is highly recommended. Any project relying on sophisticated controls and systems for energy efficiency needs the eye of an experienced commissioning agent during construction and functional testing.
Energy systems are only as efficient as they are well-installed and operated—involve the operations team during the final Construction Documents phase (or even much earlier) to make sure they are abreast of design decisions and prepared to operate in the sequence required.
Make sure mechanical spaces and locations are coordinated in the architectural and structural drawings. For example, is a duct run colliding with a beam? Is a fan coil unit placed above a door opening so that it will leak condensate on people walking into the space? Common mistakes like this can cause construction delays and poor performance during operations if not detected, so coordination of the drawings is critical, especially if your project involves integrated design and complex systems.
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.
When your final design is documented, run a final energy model for LEED documentation. Include the specifications and efficiencies of the system being purchased and installed.
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 90.1-2004 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 submittal template 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 EAc1. 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.
All the design work is implemented during construction. Have the project architect ensure that the glazing is per your specifications and that the façade system incorporates a continuous air barrier. The commissioning agent will ensure all equipment purchased is exactly what the engineer required, and that all pumps and fans meet the specifications.
If you are installing a BMS, configure and program it to specifications. If there was any change in system specifications, make sure it is accounted for in the BMS programming.
If you are installing sensors and controls, they should be configured per specifications. Surprisingly, these are occasionally miscalibrated or even reversed, causing discomfort to occupants, cost to the owner, and system malfunction.
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.
Although EAc1 is a design phase submittal, it may make sense to submit the credit after construction for LEED certification to take into account any final design changes.
The energy modeler should ensure 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.
Include supporting documents like equipment cut sheets, specifications and equipment schedules to demonstrate all energy efficiency measures claimed in the building.
It is 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 credit documentation 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.
The design team completes the LEED Online submittal template, 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 credit 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.
Install all equipment as required by the design specifications.
If your team is installing features like VAV or a peak-load demand response system for the first time, check the installation and functional testing carefully. Get the vendor involved in writing the operations specifications to reduce risk of errors.
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.
The first year of operations is usually a learning period for both the occupants and the facility manager. If your project underwent enhanced commissioning and developed an operations manual, you will have fewer miscommunications and untrained staff. Most medium and large projects install a BMS that centrally controls fans, pumps, part of the chiller and boiler load, and provides real-time energy-use data. Note that certain configurations require resetting, per feedback from users and the system itself.
Excerpted from LEED for New Construction and Major Renovations Version 2.2
Achieve increasing levels of energy performance above the baseline in the prerequisite standard to reduce environmental and economic impacts associated with excessive energy use.
Select one of the four compliance path options described below. Project teams documenting achievement using any of these options are assumed to be in compliance with EA prerequisite 2.
NOTE: LEED for New Construction projects registered after June 26th, 2007 are required to achieve at least two (2) points under EAc1.
Demonstrate a percentage improvement in the proposed building performance rating compared to 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 per ASHRAE/IESNA Standard 90.1-2004 by a whole building project simulation using the Building Performance Rating Method in Appendix G of the Standard. The minimum energy cost savings percentage for each point threshold is as follows:
* Note: Only projects registered prior to June 26, 2007 may pursue 1 point under EAc1.
Appendix G of Standard 90.1-2004 requires that the energy analysis done for the Building Performance Rating Method include ALL of the energy costs within and associated with the building project. To achieve points using this credit, the proposed design—
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 (such as for the interior, parking garage, surface parking, façade, or building grounds, except as noted above), HVAC (such as 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.
For EA Credit 1, process loads shall be identical for both the baseline building performance rating and for the proposed building performance rating. However, project teams may follow the Exceptional Calculation Method (ASHRAE 90.1-2004 G2.5) to document measures that reduce process loads. Documentation of process load energy savings shall include a list of the assumptions made for both the base and proposed design, and theoretical or empirical information supporting these assumptions.
Comply with the prescriptive measures of the ASHRAE Advanced Energy Design Guide for Small Office Buildings 2004. The following restrictions apply:
Comply with the prescriptive measures identified in the Advanced Buildings™ Core Performance™ Guide developed by the New Buildings Institute. The following restrictions apply:
Minimum points achieved under Option 3 (2-3 points):
Additional points available under Option 3 (up to 2 additional points):
Up to two (2) additional points are available to projects that implement performance strategies listed in Section Three, Enhanced Performance. For every three strategies implemented from this section, one point is available.
These strategies are addressed by different aspects of the LEED program and are not eligible for additional points under EA Credit 1.
Note: projects registered after June 26, 2007 may not use this option
Comply with the Basic Criteria and Prescriptive Measures of the Advanced Buildings Benchmark™ Version 1.1 with the exception of the following sections: 1.7 Monitoring and Trend-logging, 1.11 Indoor Air Quality, and 1.14 Networked Computer Monitor Control. The following restrictions apply:
Design the building envelope and systems to maximize energy performance. Use a computer simulation model to assess the energy performance and identify the most cost-effective energy efficiency measures. Quantify energy performance as compared to a baseline building.
If a local code has demonstrated quantitative and textual equivalence following, at a minimum, the U.S. Depart- ment of Energy standard process for commercial energy code determination, then the results of that analysis may be used to correlate local code performance with ASHRAE 90.1-2004. Details on the DOE process for commercial energy code determination can be found at www.energycodes.gov/implement/determinations_com.stm.
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.
ASHRAE offers guidance for different levels of building energy audits.
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.
ASHRAE has developed a number of publications on energy use in existing buildings, including Standard 100–1995, Energy Conservation in Existing Buildings. This standard defines methods for energy surveys, provides guidance for operation and maintenance, and describes building and equipment modifications that result in energy conservation. 2 publications referenced by this credit (ANSI/ASHRAE/IESNA 90.1–2007 and ASHRAE Advanced Energy Design Guide for Small Office Buildings 2004) are available through ASHRAE.
Energy Star is a joint program of U.S. EPA and the U.S. Department of Energy that promotes energy-efficient buildings, products, and practices.
The Solar Heating and Cooling Programme was established in 1977, one of the first programmes of the International Energy Agency. The Programme's work is unique in that it is accomplished through the international collaborative effort of experts from Member countries and the European Commission.
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.
This extensive website for energy efficiency is linked to a number of DOE-funded sites that address buildings and energy. Of particular interest is the tools directory, which includes the Commercial Buildings Energy Consumption Tool for estimating end-use consumption in commercial buildings. The tool allows the user to define a set of buildings by principal activity, size, vintage, region, climate zone, and fuels (main heat, secondary heat, cooling and water heating) and to view the resulting energy consumption and expenditure estimates in tabular form.
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 online resource, supported by Natural Resources Canada, presents energy-efficient technologies, strategies for commercial buildings, and pertinent case studies.
This website provides details process to develop an energy model.
Research warehouse for strategies and case studies of energy efficiency in buildings.
An online window selection tool with performance characteristics.
DOE website with database of energy performance of buildings across US.
This website lays out design process for developing an energy efficient building.
This website is put together for architects with ideas on hundreds of ways to improve design for lower energy demand.
This document lists multiple web based or downloadable tools that can be used for energy analyses.
This webtool is a database of strategies and vendors for energy efficient systems.
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 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.
The Commercial Buildings Energy Consumption Survey (CBECSThe Commercial Buildings Energy Consumption Survey (CBECS) is a national sample survey that collects information on the stock of U.S. commercial buildings, their energy-related building characteristics, and their energy consumption and expenditures. Commercial buildings include all buildings in which at least half of the floorspace is used for a purpose that is not residential, industrial, or agricultural, so they include building types that might not traditionally be considered "commercial," such as schools, correctional institutions, and buildings used for religious worship. CBECS data is used in LEED energy credits.) is a national sample survey that collects information on the stock of U.S. commercial buildings, their energy-related building characteristics, and their energy consumption and expenditures.
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.
These guidelines are available as a free download or can be purchased as a printed manual of 390 pages.
This Standard Practice provides useful, practical guidance on the technical issues where current research and consensus opinion have advanced, including information on design elements that can produce both a productive and pleasant work environment.
This information is of particular benefit to building design practitioners, lighting engineers, product manufacturers, building owners, and property managers. Although the text emphasizes the performance of daylighting systems, it also includes a survey of architectural solutions, which addresses both conventional and innovative systems as well as their integration in building design.
EDR offers a valuable palette of energy design tools and resources that help make it easier for architects, engineers, lighting designers, and developers to design and build energy-efficient commercial and industrial buildings in California.
This ongoing project explores the effects of computers and other information technology on resource use.
The Handbook provides up-to-date coverage of lighting development, evaluation and interpretation of technical and research findings, and their application guidelines.
The Ninth Edition provides students and professionals with the most complete coverage of the theory and practice of environmental control system design currently available. Encompassing mechanical and electrical systems for buildings of all sizes, it provides design guidelines and detailed design procedures for each topic covered. It also includes information on the latest technologies, new and emerging design trends, and relevant codes and zoning restrictions-and its more than 1,500 superb illustrations, tables, and high-quality photographs provide a quick reference for both students and busy professionals.
This manual covers nearly all disciplines involved in the design, construction and operation of green buildings.
This website is a fast growing news portal for energy efficiency in buildings showcasing success stories, breakthrough technology or policy updates.
Bimonthly publication on case studies and new technologies for energy efficiency in commercial buildings.
This is a quarterly publication for the group of energy modeling.
Compilation of research and technological breakthroughs in BIPV.
Information about energy-efficient building practices available in EDR's Design Briefs, Design Guidelines, Case Studies, and Technology Overviews.
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 weblink leads to NBI website to download the standard for free.
State of the art lighting research center at RPI provides all information terminologies of lighting design, strategies for efficient lighting and product reviews after experimental testing.
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.
ENERGY-10 is an award-winning software tool for designing low-energy buildings. ENERGY-10 integrates daylighting, passive solar heating, and low-energy cooling strategies with energy-efficient shell design and mechanical equipment. The program is applicable to commercial and residential buildings of 10,000 square feet or less.
This website includes information from the developers of DOE-2 and DOE-2 products, such as eQUEST, PowerDOE, and COMcheck-Plus.
This is the list of all software approved by DoE that can be used to run simulation for LEED purpose.
This is a tool available to download for envelope moisture analysis tool.
BIM is a popular design tool that allows collaboration among all team members and allows quick outputs of all analyses.
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.
In your supporting documentation, include spec sheets of equipment described in the Option 1 energy model or Options 2–3 prescriptive paths.
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.
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.
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.
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 sample EAc1 LEED Online credit template shows documentation of a project using the California Title 24 energy code.
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.
This template is the flattened, public version of the dynamic template for this credit that is used within LEED-Online v2 by registered project teams. This and other public versions of LEED credit templates come from the USGBC website, and are posted on LEEDuser with USGBC's permission. You'll need to fill out the live version of this template on LEED Online to document this credit.
Documentation for this credit can be part of a Design Phase submittal.
I am modelling a building that was submitted to a retrofit (envelope and all systems). For existing buildings, if the building already has shading devices, should I model the baseline with these shading devices? (eg. façade brises)?
Another doubt is about project evidences (before retrofit) for submission to LEED online. Should the existent glazing be tested for the SHGCSolar heat gain coefficient (SHGC): The fraction of solar gain admitted through a window, expressed as a number between 0 and 1. and Thermal Conductivity, or can I rely on project and/or information gathered during an on-site to demonstrate the glazing characteristics before the retrofit?
The baseline should be modeled without shading devices (see Table G3.1-5 Baseline (c)).
You should be able to document the existing glazing characteristics (original installation data, testing, etc.) or use the values found in Table A8.2.
We have a project for which we have used the Efficiency (EER) of 15.1 from 77 deg Farenheit AHRI conditions instead of the given original manufactured efficiency of 11.9 EER. What we did is that they (the manufacturer) run the equipment selection again for us considering the entering water is 77 deg F, however on our schedule we show both efficiencies. The reviewer mentions on his/her review the following: "The LEED Energy Performance Summary Report indicates that the cooling efficiency has been modeled 15.1 EER in the proposed case; however the mechanical schedule indicate that the cooling efficiency values in the actual design are 11.9. Table G3.1.10 in the Proposed building column requires that the proposed model reflect all HVAC systems at actual equipment capacities and efficiencies". Can we still demonstrate that the actual conditions are 15.1 EER by submitting the equipment selection at 77 AHRI conditions?
You should justify your modeling inputs, especially when a modeling input is different than reported for the design. For comparative purposes it is usually a good idea to report the efficiency at the standard AHRI conditions like you did in your schedule.
I am not sure how your modeling software works so I can't say how you should model it but usually you enter the efficiency at AHRI conditions and then apply a curve so the model can apply the correct efficiency at the right time.
You should explain how and why you have modeled the efficiency the way that you did.
I am working on a public building of more than 100,000 sq. ft. All of the supply and return ductwork is located either in a ceiling return enviroment or within conditioned air space. ASHRAE 90.1 requires no insulation in these situations. We are internally lining all the duct for acoustics, which carries an R-4.2 thermal rating. Is there any advantage within an air conditioned space to use R-6 rated duct insulation or is this a waste of resources?
We are working on an office building project and our query is about the baseline HVAC System definition for the energy simulation.
The building consists of three adjacent blocks and the central one is a triple height local.
We have a doubt about the interpretation of the following requirement for Ashrae 90.1 2007 - Appendix G.3.1.1: “each floor shall be modeled with a separate HVAC system”.
If we modelled one system per floor, the second floor could only include the side blocks, without the central building area (since its height is triple). Is this interpretation correct or should we model separate systems for each block of the same floor?
You use the floor area for each floor. So the first floor system covers the single floor height blocks and the central one. The model should then handle the volume of the central one when auto-sizing the system, etc.
I read from your description of credit EAc1 and from the LEED Reference guide for LEED2.2 that there are 4 options for credit compliance, one of those being using the Core Performance for buildings under 100,000 sq ft. However on the LEED on-line v2.2 EAc1 template , there are only three options listed that you can choose from and non of them are the Core Performance option listed here as number 3. Can you provide any guidance on this, as this would be the option we need for our project. Thanks!
Do not select any of the options on the template. Provide a narrative in the box on the last page and check the alternative compliance box. Then upload your documentation.
Hi, we have received a review comment on a project stating that " Insufficient information has been provided to confirm electrical energy savings reported in table EAp2-10 for service hot water heating".
ASHRAE Table G3.11(b) states that for service water heating, where the energy source is electricity, the heating method shall be electrical resistance. We understand this to effectively mean a COP of 1. The proposed building uses ground source heat pumps with COPs in the region of 3.25. We provided the schedule of operations used (based on ASHRAE 90.1 user manual) and the inputs for the baseline building in the narrative and supplemental tables. Design documents showing the efficiency of the heatpumps was also provided. All inputs are the same except the efficiency of the hot water heating equipment.
We are not sure what the issue could be and since we are about to go into ab appeal we wanted to check if there is any fundamental misunderstanding on our side with regards to the baseline building service hot water system.
Your assumption of a COP of 1 is incorrect. The baseline efficiency should be according to Table 7.8 in 90.1. This should increase your savings.
Simply explain how you have modeled the baseline and proposed systems and how that reasonably produces the level of energy savings claimed. Project teams routinely claim energy savings associated with hot water demand reduction so make sure to explain that you are not doing so.
Great, thanks. Never thought we would have to go to such lengths to show heat pumpA type of heating and/or cooling equipment that draws heat into a building from outside and, during the cooling season, ejects heat from the building to the outside. Heat pumps are vapor-compression refrigeration systems whose indoor/outdoor coils are used reversibly as condensers or evaporators, depending on the need for heating or cooling. In the 2003 CBECS, specific information was collected on whether the heat pump system was a packaged unit, residential-type split system, or individual room heat pump, and whether the heat pump was air source, ground source, or water source. savings over electric resistance.
Are there any instances where you can ask the LEED reviewers to clarify based on the fact that the fundamentals of the two technologies are quite easy to see? We will go to appeal if we have to but it doesn't make sense that we got all the savings denied even though we included information in the supplemental tables and all the design documentation. Our narrative even included ASHRAE and other industry examples of expected savings and showed how they were in line with our results.
Having to explain what you have done to justify your savings does not strike me as too much to ask. It may be obvious to you but it apparently was not obvious to the reviewer. We have reviewed thousands of models submitted for LEED Certification. Sometimes we miss the obvious but 99 times out of 100 there is a very good reason the reviewer has asked for justification. What percent savings are you claiming for service hot water? Typically the reviewer would evaluate the input (system efficiencies) vs the output (percent savings). If there is not alignment between the two a question like this will be raised.
You can send a question to the reviewer through the GBCI web site under the Contact Us. You can also challenge the denial this way before you file the appeal but you should be absolutely certain that the reviewer made an error and should not have done so based on the documentation you provided.
It is very hard for me to provide advice without seeing the full comment from the reviewer and the documentation you submitted. Not sure why all the savings would be denied since reviewers are encouraged to provide partial credit if at all possible.
We claimed 70% reduction, The system COP is 3. 60% is just based on the difference between the efficiencies and the rest due to compressor heat addition on the load side of the heatpump. We provided our methodology after the initial review feedback and it was still denied at final review. I do agree that we might be missing something in our explanation that we think is obvious so getting clarity on the comment via GBCI website might be the best option. As reviewers for our local green building code we do understand that this happens sometimes. If anything, understanding why we cannot get partial credit for the efficiencies will help us structure our appeal.
Thank you for your time Marcus.
Your explanation and the savings on this issue appear to be in alignment to me.
Were there other issue with the model that contributed to the overall denial?
For final review we were denied all the service hot water savings. Partial credit was given in terms of all the other interventions. Being a hotel, service hot water was a large percentage of the total building energy use. After the initial review we included details on peak sizing, schedules of operation and efficiency. For final review all the other issues were passed except the hot water heating savings.
You may have a case so challenge the final response with GBCI. Good luck.
As far as I can tell, you deserve an explanation from USGBC of why you were not granted credit. Is it possible you took gallons of hot water savings also and they have issue with how you calculated those, but failed to word it properly in the review comments?
Based on previous comments on the forum we made a point of not trying to get credit for reduced water demand (even though low flow fittings are used). The output reports we submitted also showed that the total volume of water heated in a year was equal between the two models.
We would like to ask something regarding a comment from a reviewer for EAc1, this is a rather vague comment in our view. Our project consist of around 5 buildings connected through a ground water loop supplied by a well, the cooling/heating process occur at a project scale not a campus scale. The reviewer said:
"It appears from the description in the Commissioning Report provided in EAp1: Fundamental Commissioning that a campus energy source is used for the Proposed Case building heating and cooling. Note that all New Construction, Schools, Core and Shell, and Commercial Interiors projects registered with the USGBC on or after 05/28/2008, and using district thermal energy, are required to follow the guidance of the document "Required Treatment of District Thermal Energy in LEED?NC version 2.2 and LEED for Schools, version 1.0" (DES v1) dated May 28, 2008 which can be accessed at: www.usgbc.org/resources/des-district-energy-systems-guidance-v22-and-v20.... Optionally, in lieu of following the required version 1.0 guidance, the project may choose to follow the guidance of the document "Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009? Design and Construction" (DES v2) dated August 10, 2010 which can be accessed at: www.usgbc.org/resources/des-district-energy-systems-guidance-v22-and-v20.... If following version 1 of the District Thermal Energy guidance, please provide a Step 1 EAc1 template and supporting documentation if pursuing 2 points, or both a Step 1 and a Step 2 template and supporting documentation if pursuing more than 2 points, and provide sufficient information to show that the District Energy Requirements document has been appropriately applied to the project. If following version 2 of the District Thermal Energy guidance, please follow the requirements of either Option 1 or Option 2, as appropriate for your situation. The submitted LEED review documentation must clearly state which method, District Thermal Energy guidance v. 1.0 (DES v1 - May 2008) or District Thermal Energy guidance v. 2.0 (DES v2 - August 2010) was used".
The commissioning Report is not very clear on this, the Cx1. Commissioning (Cx) is the process of verifying and documenting that a building and all of its systems and assemblies are planned, designed, installed, tested, operated, and maintained to meet the owner's project requirements.
2. The process of checking the performance of a building against the owner's goals during design, construction, and occupancy. At a minimum, mechanical and electrical equipment are tested, although much more extensive testing may also be included. Agent does not say that a campus energy source is used for the Proposed Case, but it only says the ground water source well pumps (campus) are out of his/her scope (which by the way are not energy source in any way). Thus we cannot follow any of these guidances suggested since the cooling and heating are provided at a project level instead of a campus level , given that the groundwater is considered a thermal storage only in this case. Has abnybody had any experience on this type of comment?
The reviewer appears to not be clear on this system and based on your description, I am not clear either. What is this ground water which is circulated to all of the building used for? Are you ignoring the pumping energy for this system in your models? Your description raises many questions and I think the reviewer sounds like they also have questions. Perhaps they just want an explanation.
We have several buildings connected to a closed ground water loop that distributes water to each building, the loop is also connected to a heat exchanger that is connected to an open water loop getting water from a well. The water coming to the building through the ground water loop is only used a s thermal storage but the energy conversion is done at a building scale, which this one in particular is having 10 water source heap pumps. Therefore in our view we would not have to comply with the district cooling guidance. What are your thoughts on this?
Does this closed loop and the open well serve more than just your buildings?
If so how are you accounting for the other loads on the loop/well?
The general approach in the DES would be to create a virtual well and loop which has been proportionally downsized to meet the loads of the buildings. This should also account for the pumps on the system.
Sounds like the reviewer wants more information on the system to make sure you are accounting for the all the energy use associated with it.
I have a general question about the appliance credit with regards to how it would be affected by a change in regulations mid-project. Federally mandated energy regulations that go into effect for all manufacturers of refrigerators on 9/15 will require anything manufactured after this date to be 35% more efficient than today’s energy star product in order to retain a 2014 Energy Star rating.
At what point to the products you put in this building have to be Energy Star in order to qualify?
On delivery date? Occupancy date?
So appliances are being delivered to my project between Sept 1-Sept 30 – can they all be the 2013 model and still qualify for leed? Could you mix refrigeration on a project like this with some 2013 qualifying models and some 2014 models?
Thanks in advance
LEED projects are held to the requirements that are in place at the time of the project's registration.
We have got Design review comments and EAc1- achieved 17 % with 2 points.
My question is , we got modification in HVAC systems and getting power reduction now, It is increased more energy saving and increased 2 more points . Can we re submitt EAc1 credit energy modeling during Construction submittal?
If your original models were based on the design and these were changes in construction you are supposed to resubmit it. Make sure to explain the changes in some detail. Keep in mind that it will only get one additional review so you need to get it right the first time.
If my building uses district chilled water from central plant of the campus, and the entire campus buildings are not part of the energy modeling - what maximum points are avilable to earn?
If you do not follow the district energy guidelines from USGBC and treat the chilled water as purchased energy all of the points are available.
Earlier we have submitted so many projects and received certification. For each project we have updated energy simulation and summary report based on the previous energy modeling comments from the review team,in line for the fan power calculation, we have done the calculation based on the USGBC review team approved fan power calculation from the previous project.
But still we have received comments, they can say for that review team is different for different project. what i want to say is it should be consistent towards technical point of view ,not simply writing comment back to us to understand the energy saving concept. i do not understand . Please anyone clarify if anything behind this.
There are many different reviewers but there should be relative consistency in the reviews. Without knowing the specific issue the reviewer is raising it is hard to say what this particular reviewer saw to make them question the baseline fan power calculations.
According to ASHRAE 90.1-2007 G3.1.1 for system 6, each floor shall be modeled with a separate HVAC system. Also according to table G3.1.1 (b) temperature and humidity control set points and schedules shall be the same for proposed and baseline building..
Finally, system design supply airflow rate for the baseline shall be based on a supply-air-to-room-air temp difference of 20 °F. (G188.8.131.52)
If there are two spaces in the same floor with different temperature set points. How can it be modeled with one system per floor with one supply temperature?
can it be possible to split the system?
You can model a separate system 6 for spaces that have major differences with the primary system 6 on that floor. Differences could include temperature set points. This only makes logical sense.
Energy modeling using Trace 700 software , Can anyone tell me, Is it complying ASHRAE 90.1-2004 standards for LEED certification. Is it same like VisualDOE and eQuest software.
TRACE meets the software criteria in Appendix G and can be used for LEED submissions.
Can we use ASHRAE 901 2007 instead of 2004 for LEED NC 2.2?
Yes you can but your savings will likely be less.
My question is whether it is possible to edit the tables in the LEED templates. I have searched this forum and other possible sources but have not found an answer.
Currently we are working in the LEED template for EAc1 Optimize Energy Performance. The issue is that we have more inputs than spaces in some of the tables. For example Table 1.8.1 "Baseline Performance - Performance Rating Method Compliance" and Table 1.4 "Comparison of Proposed Design vs Baseline Design".
My question is if it is possible to add another row to these tables. If yes, then how do I go about doing that. If no, then what possible work around is there if we have more data to input.
I do not think it is possible to add another row.
Work around would be to submit a spreadsheet with the results. Maybe you could consolidate end uses?
Thank you for your reply.
I think using the spreadsheets and consolidating the results may be a good idea. We will try that.
We have a project (1 story auditorium) that is being demolished to the slab and rebuild having the basic foundation and a few columns. could that be considered a major renovation since we do not have the option of redefine the orientation of the building? or should it be considered a totally new building?
It is a new building in my opinion.
We received a comment from GBCI that kitchen make-up units should be modeled identical in the proposed and baseline building models. They stated that kitchen make-up units are process loads. I disagreed with their interpretation, but I have been rejected twice.
I modeled the baseline with SZHP system and proposed as-design which is GSHP system. I set the outdoor air rate identical between the baseline and proposed building models. I set the baseline fan power to the requirements of the appendix G and proposed fan power as-design.
Please send your comments.
app G does not have a baseline for make-up fan. this kind of device is deemed to be a process load. You can claim some small saving basing on good motor efficiency.
We have two projects on one site, a parking garage (not a LEED project) and an Office/Hangar which will be submitted for LEED certification (registered under v2.2). The Office/Hangar will get energy from the PV’s located on the roof of the parking structure. The question is whether the garage light fixtures have to be included in the energy model or in the mercury calcs.
LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org. #2028 is the closest interpretation that I could find, but does not help us entirely due to the phrase “If the buildings are included as part of the LEED scope of work” – in our case not sure if the garage is clearly included in the LEED scope of work, as it cannot be certified (per MPR), but is holding the PVs. Can we make the case that it offers structural support only, & therefore does not have to be included? Similar to having a PV arrays on open land, but we put it up on the building?
Since the LEED Minimum Program Requirements were introduced with LEED 2009, it has become much easier to answer this kind of question definitively, according to set rules. For a v2.2 project, it's harder to say definitively. So I will just pretend that it's a v2009 project, and say that you can include the energy in the PV in your LEED scenarios, and not include the parking garage, but only if the parking garage is appropriately left out of the LEED project boundary. However, if the garage is being built along with the office, and if it is used to support the normal operations of the office, it should be in your LEED project boundary, and count in all relevant credits.
Per the LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org. about certifying parking garages, it's true that it cannot be certified, but that should not be interpreted to mean that it should not be included in the LEED project boundary, if it's in the scope of work.
This project is a hotel: guestrooms are provided with keycards, so when guestrooms are not occupied all lighting fixtures are automatically shut-off. Can credits be taken in the proposed case for 10% power adjustment for automatic lighting control as per "ASHRAE 90.1:2007 TABLE G3.2 - Case (2): Occupancy sensor"?
You can do better than that - see Appendix D4 in the Advanced Energy Modeling Guide for LEED for a description of a methodology to claim 45% savings.
The project we are working on is registered under LEED for Core and Shell v2.0. The credit language for EA Cre 1 says we should conduct energy simulation according to ASHRAE 90.1-2004 Appendix G. Is it however permitted to use a newer version instead - ASHRAE 90.1 -2007 - since it's more stringent?
I think it would be allowed but you would probably leave points behind too.
I have a question regarding energy simulation (option 1 whole building simulation) for a baseline building. How should we calculate fan power: should we calculate it seperately for supply, return and exhaust fans using equation in section G184.108.40.206 of Appendix G or should we calculate it only once for supply air volume and then divide obtained power by two to get supply and exhaust fan power?
The G220.127.116.11 fan power calculations include all of the HVAC fans in the baseline system.
I am working on a office project in climate zoneOne of five climatically distinct areas, defined by long-term weather conditions which affect the heating and cooling loads in buildings. The zones were determined according to the 45-year average (1931-1975) of the annual heating and cooling degree-days (base 65 degrees Fahrenheit). An individual building was assigned to a climate zone according to the 45-year average annual degree-days for its National Oceanic and Atmospheric Administration (NOAA) Division. 5, and has no economizerAn economizer is a device used to make building systems more energy efficient. Examples include HVAC enthalpy controls, which are based on humidity and temperature. except server room, which has water economizer. The baseline case has system 7 for office space and system 3 for server room.
According to G18.104.22.168 “Outdoor air economizers shall be included in baseline HVAC Systems 3 through 8 based on climate as specified in Table G22.214.171.124A.” Therefore air economizers shall be included in the baseline systems for office space and for server room.
But according to 11.3.2 e “Budget building systems as listed in Table 11.3.2A shall have outdoor air economizers or water economizers, the same as in the proposed building,” Therefore no economizers shall be included in the system for office space, and water economizer shall be included in the system for server room.
Which is right for this project?
Apply the Appendix G requirements. The section 11 requirements are not used when modeling this credit, so ignore them.
I need help interpreting a comments received back from the GBCI on our construction submission regarding EAC1.
This project was registered under LEED V2.2 NC, it is a gymnasium addition to an existing school which utilizes extensive daylighting. Daylighting was modeled in AGI 32 in spring, fall & winter (when the gymnasium is in use) at intervals during the day at 9am, 12pm, 3pm and 5pm and the spaces are designed utilizing skylights and Kalwall such that the lights are almost never turned on and we have a stepped ballast system that allows for different lighting situations from dim to full game lighting in the gymnasium. For reference, they accepted EQ8.1 for daylighting 100% of occupied spacesOccupied Spaces are defined as enclosed spaces that can accommodate human activities. Occupied spaces are further classified as regularly occupied or non-regularly occupied spaces based on the duration of the occupancy, individual or multi-occupant based on the quantity of occupants, and densely or non-densely occupied spaces based upon the concentration of occupants in the space. in the review. Lighting power densities were calculated using the manufacturers stated watts per fixture divided by the area of the space in question. Our lighting schedule in Trace 700 was determined using the owner's actual schedule of use for the spaces and the outputs from our daylighting calculations which stated when our daylight controls would turn the lights off.
However, we received a comment on our EAC1 stating the following:
"The energy savings (85.7%) reported for interior lighting between the proposed model & baseline model in the Table 1.8.2 of the template is unsubstantiated based on the building average lighting power density of 0.68 W/sf for the Proposed model and 0.97 W/sf for the Baseline model provided in interior lighting power density calculations. Even with the inclusion of the occupancy sensors for the non-mandatory spaces per Section 126.96.36.199 in the Proposed model, the savings must not be greater than 40%."
We do not understand why there is a cap on lighting energy savings at 40%. Can anyone please explain this?
Either the reviewer missed the information or you did not provide the information in EAc1 on the lighting controls. Often the individual who reviews EAc1 is not the same one reviewing EQc8.1 and you must indicate in EAc1 that you have a dimming system. The EAc1 reviewer is basing the 40% on the data they saw - the difference in LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. plus the 10% occupancy sensor credit.
In your response explain the lighting controls and how you modeled them.
I am working on a hotel project now, and has one query regarding one assumption on FCU operation.
According to M&E designer, when the guestroom is not occupied, the FCU will work on medium speed and temperature will be reset to a higher one, whose flowrate is around 70% of that under high speed. Since a hotel guestroom can not 100% occupied at daytime, we assume 50% of guestrooms are unoccupied at daytime and the FCUs are working at medium speed.
In such a case, I think for baseline we shall also use similar operation character. 70% flowrate for the unoccupied guestroom.
Is this acceptable?
any comments are welcome.
I don't think so. The schedules must be identical in both models unless you perform an exceptional calculation to show savings. The baseline system airflow should be determined according to G188.8.131.52. Systems 1 or 2 which are used in the baseline for hotel guestrooms are constant volume systems.
Let me know if this response does not answer your question.
Marcus, thanks for your reply.
I have three further questions which need your kind advice.
1. Assume thermostat setting is 24 degree +- 1 degree range; when the room temperature drops to 22 degree, shall the PTAC fan be cycling or the PTAC fan is shut down?
2. In the proposed model, half of the FCUs will be operating at medium speed for "assumed" unoccupied time, it will be very hard to justify this.
if PTHP system is running at full speed all the time, our assumption above (which is reasonable in some sense) will give us extra saving which may not be acceptable.
3. For hotel project, when we are doing the zoning; some internal guestrooms which are adjacent to each other are combined; for the baseline PTHP, the larger system size is, the worse the efficiency is (6.8.1D).
It seems this shall not be the truth, but I have not other choice.
1. Not sure I understand the situation. Heating or cooling, set-back or not, occupied vs unoccupied?
2. The assumed occupancy should be based on the expected occupancy of the hotel. The owner should be able to supply you with expected occupancy rates.
3. If they are combined in the proposed case then it is certainly fine to combine them in the baseline. You are allowed to combine units - see Table G3.1.1-#7 and #9.
Thanks for your reply, Marcus. Appreciate a lot.
Regarding Point 1, my project is a hotel located at Singapore, and only cooling is needed for year long.
Local common practice is: when guestroom is not occupied (sensed by card reader at door), the fresh air won't be shut down and the thermostat can be offseted to higher level(say, from 24 to 26).
For baseline, from discussion above and the info digged out from google search, I would think for baseline model: fresh air shall follow same control logic which is constant; for supply air fan, constant speed, run for 24 hours no matter occupied or not occupied ; thermostat setting follows proposed schedule.
I am using IES, so this kind of control logic above is prerequisite for simulation.
However if above points are true, we are taking advantage of medium speed fan power.
IF you have further advice/comment, please kindly give.
Section 184.108.40.206.3 requires that the outside air is shut off during unoccupied periods. This is a mandatory provision and the Proposed design must comply. So the outside air is shut down during unoccupied periods in both cases and the fans cycle with the temperature settings.
Fan schedules must be identical. Temperature settings must be identical.
You can then claim any savings associated with the difference in fan power due to fan speed based on the design. Baseline fans run at constant speed, proposed run as designed.
A project has 3 floors - First, second and third. The first floor consists of auditorium and is double height. There is a mezzanine floor in the first floor which covers upto 30% of the total floor area. The mezzanine floor consists of only one conditioned zone-Gymnasium which is not occupied regularly and covers only a small portion of mezzanine floor. The other areas in the mezzanine floor is lobby and toilets. Do we have to consider the project as three storey or four storey for baseline system selection? The baseline system and the savings is totally dependent on number of floors.
Sounds like 4 stories to me since the mezzanine contains some conditioned spaces.
LEED uses Gross floor areaGross floor area (based on ASHRAE definition) is the sum of the floor areas of the spaces within the building, including basements, mezzanine and intermediate‐floored tiers, and penthouses wi th headroom height of 7.5 ft (2.2 meters) or greater. Measurements m ust be taken from the exterior 39 faces of exterior walls OR from the centerline of walls separating buildings, OR (for LEED CI certifying spaces) from the centerline of walls separating spaces. Excludes non‐en closed (or non‐enclosable) roofed‐over areas such as exterior covered walkways, porches, terraces or steps, roof overhangs, and similar features. Excludes air shafts, pipe trenches, and chimneys. Excludes floor area dedicated to the parking and circulation of motor vehicles. ( Note that while excluded features may not be part of the gross floor area, and therefore technically not a part of the LEED project building, they may still be required to be a part of the overall LEED project and subject to MPRs, prerequisites, and credits.) (as defined by ASHRAE) for credits PIf3, EAp1, EAp2, EAc1, EAc2, EAc6, and MRc1. The definition is as follows:
"Gross Floor Area: (based on ASHRAE definition) Sum of the floor areas of the spaces within the building, including basements, mezzanine and intermediate-floored tiers, and penthouses with headroom height of 7.5 ft (2.2 meters) or greater. Measurements must be taken from the exterior faces of exterior walls OR from the centerline of walls separating buildings. Excludes non‐enclosed roofed‐over areas such as exterior covered walkways, porches, terraces or steps, roof overhangs, and similar features. Excludes air shafts, pipe trenches, and chimneys."
Is floor area for vertical circulation (stairs, elevators) to be counted on each floor when determining the building’s gross floor area?
What about a walkway that is 8-feet above the room’s floor level but enclosed within the double height space of the room – is only the floor area of the walkway used or is the area defined from the walls enclosing the space within which the walkway is located? This will effect the HVAC system type used.
Is there any issue if the sum of the areas used in the energy model (as listed in Table EAp2-1 Space Summary) are not within 10% of this building gross floor area?
Yes internal circulation spaces count.
Only the floor area of the walkway would count.
If the difference is not within 10% the reviewer will likely flag it and ask for an explanation.
Thanks Marcus for your quick response. Just to be clear, the stair and elevator spaces would have to count 12 times in a 12-story building (each floor)?
Yes each floor counts.
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Documentation of EAc1 is completed through EAp2. The same energy-efficiency measures contribute to both credits, with additional measures needed to earn points for EAc1.
Limits on interior and exterior lighting can help in reducing energy loads.
Use daylight sensors to control electrical lighting, reducing electricity use from natural daylight, as well as cooling loads.
Excessive glazing in the name of providing views can reduce energy efficiency. This does not have to be the case, however.
Building systems contributing to energy efficiency are to be commissioned.
Earning this credit helps to realize the operational benefits of energy-efficient design.
Projects using energy modeling for EAc1 can earn points from onsite renewables, while also earning points under EAc2.
The computer model developed for EAc1: Option 1 is calibrated and refined under M&V.
The quantity of green power purchases is based on the energy model created for EAc1, if one is created. Green power does not help earn points under EAc1, however.
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