This prerequisite is a big one, not only because it’s required for all projects, but also because it feeds directly into EAc1: Optimize Energy Performance, where about a fifth of the total available points in LEED are at stake. Master these minimum requirements, and you can use the same compliance path as in EAp2 to earning points.
You won’t earn the prerequisite by accident, though. Although “energy efficiency” is on everyone’s lips, the mandatory and performance-based requirements for EAp2 go beyond code compliance in most places. That said, there is nothing to stop you from meeting the requirements with a reasonable amount of effort, and the environmental benefits as well as the operational cost savings are significant.
Most projects start by choosing which of the three available compliance paths to follow. We’ll look at them each in turn.
Option 1 alone gives you access to all of the points available through EAc1, and offers the most flexibility in giving you credit for innovative designs.
First, you need to meet the mandatory requirements of ASHRAE 90.1-2007 for all major components, including the envelope, HVAC, lighting, and domestic hot water. ASHRAE 90.1 has had some changes and new mandatory requirements since the 2004 version, which was referenced on previous LEED systems, so be sure to review the standard carefully.
Energy efficiency is an area where it behooves project teams to start early and work together to maximize savings. Playing catch-up later on can be costly.Second, you need to demonstrate a 10% savings (5% for existing buildings) for your designed building compared with a baseline case meeting the minimum requirements of ASHRAE 90.1 (or Title 24-2005, Part 6 for California projects). You do this by creating a computer model following rules described in Appendix G of ASHRAE 90.1.
Computer modeling offers the following key advantages:
Your building type may not have a choice—you may have to follow this path, because both Options 2 and 3 are prescriptive compliance paths that are only available to specific building types and sizes.
However, if your building type and size allow, and you don’t want to embark on the complex process of computer modeling, which also requires expert assistance from a modeler or from a member of the mechanical engineer’s team, the prescriptive compliance paths are a good way to earn the prerequisite simply by following a checklist.
Passive design strategies such as shading to reduce solar heat gain are the most cost-effective ways to improve energy performance.Note, however, that when you get to EAc1, there are a lot fewer points on the table for the prescriptive paths, and that you have to follow each prescriptive requirement. These paths also require more collaboration and focus early on in design than you might think. The design team must work together to integrate all of the prescriptive requirements, and Option 3 even requires documentation of certain design processes.
The Advanced Energy Design Guides are published by ASHRAE for office, warehouse, and retail projects less than 20,000 ft2—so if you don’t fall into one of those categories, you’re not eligible for this path.
These guides outline strategies to reduce energy use by 30% from 2001 levels, or an amount equivalent to approximately 10%–14% reduction from ASHRAE 90.1-2007. If you choose this compliance path, become familiar with the list of prescriptive requirements and commit to meeting all of them.
The Core Performance Guide path is a good option if all of the following are true:
Comply with all requirements within Sections 1 and 2 of the guide. If you choose this path, become familiar with the list of prescriptive requirements and commit to meeting them. Also note that it’s not just a list of prescriptive requirements, but a prescribed process for achieving energy efficiency goals. You must demonstrate that you considered a couple of alternate designs, for example, and that certain team meetings were held.
Energy efficiency offers a clear combination of environmental benefit and benefit to the owner through reduced operational expenses, and potentially reduced first costs, if you’re able to reduce the size and complexity of your HVAC system with a more efficient envelope.
High-tech HVAC systems, and onsite renewable energy generation are often signature components of green buildings, but consider these strategies more “icing” on the cake, rather than a place to start. Start with building orientation and passive design features first. Also look at envelope design, such as energy-efficient windows, walls and roof, before looking at HVAC and plug loads. A poorly designed envelope with a high-tech HVAC system is not, on the whole, efficient or cost-effective.
Projects connected to district energy systems will not be able to utilize the system efficiencies of the base plant to demonstrate compliance with the prerequisite. They can plan on benefiting from these systems under EAc1, however.
Focusing on energy efficiency and renewable energy generation can seem to add costs to a project, but there are a variety of utility-provided, as well as state, and federal incentives available to offset those premiums. (See Resources.)
Ideally if the software you are using cannot model a technology directly then seek a published workaround related to your software. If you can't find a published workaround then model it as you think it should be modeled and explain how you have modeled it in the preliminary LEED submission.
No, not if it is part of the LEED project. However, there is an exemption for existing building envelopes in Appendix G that allow you to model the existing condition in the baseline so you do not pay a penalty.
No, not for an existing building.
You must model accurately. Since you don't have enough savings in the building energy, find savings in the process. Either you will be able to demonstrate that compared to a conventional baseline the process being installed into the factory is demonstrably better than "similar newly constructed facilities," allowing you to claim some savings, or the owner needs to install some energy-saving measures into the process to get the project the rest of the way there. Either option can be difficult, but not impossible.
Account for process load reductions through the exceptional calculation method. A baseline must be established based on standard practice for the process in your location. Any claim of energy savings needs a thorough narrative explaining the baseline and the strategy for energy savings along with an explanation of how the savings were calculated.
It is common to have a 80%–90% process load in a manufacturing facility. The 25% default in LEED is based on office buildings. If you think your load is lower than 25%, it is recommended that you explain why in a short narrative. It is also recommended to briefly explain it if your load is 25% exactly, since that level commonly reveals that the process loads were not accurately represented.
The energy savings are based on the whole building energy use—building and process. LEED does not stipulate exactly where they come from.
For LEED 2009 you'll need touse 90.1-2007. There were some significant changes in 90.1-2010—too many to account for in your LEED review, and your project would also have a much harder time demonstrating the same percentage energy savings.
Yes according to LEED, although it is not recommended as a best practice, and it is usually more cost-effective to invest in energy savings in the building.
You can assume exterior lighting savings for canopies against the baseline, but not the shading effects of canopies.
If exterior lighting is present on the project site, consider it as a constant in both energy model cases.
Any conditioned area must be included in the energy model.
The Energy Star portion of the form does not apply to international projects.
Use the tables and definitions provided in 90.1 Appendix B to determine an equivalent ASHRAE climate zone.
International projects are not required to enter a Target Finder score. Target Finder is based on U.S. energy use data.
For Section 184.108.40.206c, a manual control device would be sufficient to comply with mandatory provisions.
Submitting these forms is not common; however, it can be beneficial if you are applying for any exceptions.
Use the building area method.
Although there is no formal list of approved simulation tools, there are a few requirements per G2.2.1, including the ability of the program to provide hourly simulation for 8760 hours per year, and model ten or more thermal zones, which PHPP does not meet.
The automated Trace 700 report provides less information than is requested by the Section 1.4 tables spreadsheet. The Section 1.4 tables spreadsheet must be completed.
Assign HVAC systems as per Appendix-G and Section 6 but set thermostatic setpointsSetpoints are normal operating ranges for building systems and indoor environmental quality. When the building systems are outside of their normal operating range, action is taken by the building operator or automation system. out of range so that systems never turn on.
If it is only used for backup and not for regular use such as peak shaving—no.
SHGC is not a mandatory provision so it is available for trade-off and can be higher than the baseline.
You generally wouldn't need to upload any documentation, but particularly for a non-U.S. project, it may help to provide a short narrative about what they are based on.
Discuss your project’s energy performance objectives, along with how those are shaping design decisions, with the owner. Record energy targets in the Owners Project Requirements (OPR) for the commissioning credits EAp1 and EAc3.
You won’t earn this prerequisite by accident. The energy efficiency requirements here are typically much more stringent than local codes, so plan on giving it special attention with your team, including leadership from the owner.
Consider stating goals in terms of minimum efficiency levels and specific payback periods. For example: “Our goal is to exceed a 20% reduction from ASHRAE 90.1, with all efficiency measures having a payback period of 10 years or less.”
Develop a precedent for energy targets by conducting research on similar building types and using the EPA’s Target Finder program. (See Resources.)
For Option 1 only, you will need to comply with the mandatory requirements of ASHRAE 90.1-2007, to bring your project to the minimum level of performance. The ASHRAE 90.1-2007 User’s Manual is a great resource, with illustrated examples of solutions for meeting the requirements.
ASHRAE 90.1-2007 has some additional requirements compared with 2004. Read through the standard for a complete update. The following are some samples.
The prerequisite’s energy-reduction target of 10% is not common practice and is considered beyond code compliance.
Indirect sunlight delievered through clerestories like this helps reduce lighting loads as well as cooling loads. Photo – YRG Sustainability, Project – Cooper Union, New York A poorly designed envelope with a high-tech HVAC system is not, on the whole, efficient or cost-effective. Start with building orientation and passive design features first when looking for energy efficiency. Also look at envelope design, such as energy-efficient windows, walls and roof, before looking at HVAC and plug loads. HVAC may also be a good place to improve performance with more efficient equipment, but first reducing loads with smaller equipment can lead to even greater operational and upfront savings. A poorly designed envelope with a high-tech HVAC system is not, on the whole, efficient or cost-effective.
Don’t plan on using onsite renewable energy generation (see EAc2) to make your building energy-efficient. It is almost always more cost-effective to make an efficient building, and then to add renewables like photovoltaics as the “icing” on the cake.
Some rules of thumb to reduce energy use are:
Find the best credit compliance path based on your building type and energy-efficiency targets. Use the following considerations, noting that some projects are more suited to a prescriptive approach than others.
Option 1: Whole Building Energy Simulation requires estimating the energy use of the whole building over a calendar year, using methodology established by ASHRAE 90.1-2007, Appendix G. Option 1 establishes a computer model of the building’s architectural design and all mechanical, electrical, domestic hot water, plug load, and other energy-consuming systems and devices. The model incorporates the occupancy load and a schedule representing projected usage in order to predict energy use. This compliance path does not prescribe any technology or strategy, but requires a minimum reduction in total energy cost of 10% (5% for an existing building), compared to a baseline building with the same form and design but using systems compliant with ASHRAE 90.1-2007. You can earn additional LEED points through EAc1 for cost reductions of 12% and greater (8% for existing buildings).
Option 2: Prescriptive Compliance Path: ASHRAE Advanced Energy Design Guide refers to design guides published by ASHRAE for office, school, warehouse, and retail projects. These guides outline strategies to reduce energy use by 30% from ASHRAE 90.1-2001 levels, or an amount equivalent to a 10%–14% reduction from the ASHRAE 90.1-2007 standard. If you choose this compliance path, become familiar with the list of prescriptive requirements and commit to meeting them. (See the AEDG checklist in the Documentation Toolkit.)
Option 3: Prescriptive Compliance Path: Advanced Buildings Core Performance Guide is another, more basic prescriptive path. It’s a good option if your project is smaller than 100,000 ft2, cannot pursue Option 2 (because there is not an ASHRAE guide for the building type), is not a healthcare facility, lab, or warehouse—or you would rather not commit to the energy modeling required for Option 1. Your project can be of any other building type (such as office or retail). To meet the prerequisite, you must comply with all requirements within Sections 1 and 2 of the guide. If you choose this path, become familiar with the list of activities and requirements and commit to meeting them. (See Resources for a link to the Core Performance Guide and the Documentation Toolkit for the checklist of prescriptive items.)
EAc1: Optimize Energy Performance uses the same structure of Options 1–3, so it makes sense to think about the credit and the prerequisite together when making your choice. In EAc1, Option 1 offers the potential for far more points than Options 2 and 3, so if you see your project as a likely candidate for earning those points, Option 1 may be best.
Hotels, multifamily residential, and unconventional commercial buildings may not be eligible for either Option 2 or Option 3, because the prescriptive guidance of these paths was not intended for them. Complex projects, unconventional building types, off-grid projects, or those with high energy-reduction goals are better off pursuing Option 1, which provides the opportunity to explore more flexible and innovative efficiency strategies and to trade off high-energy uses for lower ones.
If your project combines new construction and existing building renovation then whatever portion contains more than 50% of the floor area would determine the energy thresholds.
Options 2 and 3 are suitable for small, conventional building types that may not have as much to gain from detailed energy modeling with Option 1.
Meeting the prescriptive requirements of Options 2 and 3 is not common practice and requires a high degree of attention to detail by your project team. (See the Documentation Toolkit for the Core Performance Guide Checklist.) These paths are more straightforward than Option 1, but don’t think of them as easy.
Options 2 and 3 require additional consultant time from architects and MEP engineers over typical design commitment, which means higher upfront costs.
Option 1 references the mandatory requirements of ASHRAE 90.1-2007, which are more stringent than earlier LEED rating systems that referred to ASHRAE 90.1-2004.
Option 1 energy simulation provides monthly and annual operating energy use and cost breakdowns. You can complete multiple iterations, refining energy-efficiency strategies each time. Payback periods can be quickly computed for efficiency strategies using their additional first costs. A building’s life is assumed to be 60 years. A payback period of five years is considered a very good choice, and 10 years is typically considered reasonable. Consult the OPR for your owners’ goals while selecting your efficiency strategies.
Option 1 energy simulation often requires hiring an energy modeling consultant, adding a cost (although this ranges, it is typically on the order of $0.10–$0.50/ft2 depending on the complexity). However, these fees produce high value in terms of design and decision-making assistance, and especially for complex or larger projects can be well worth the investment.
All compliance path options may require both the architectural and engineering teams to take some time in addition to project management to review the prescriptive checklists, fill out the LEED Online credit form, and develop the compliance document.
The architect, mechanical engineer, and lighting designer need to familiarize themselves and confirm compliance with the mandatory requirements of ASHRAE 90.1-2007, sections 5–9.
Use simple computer tools like SketchUp and Green Building Studio that are now available with energy analysis plug-ins to generate a first-order estimate of building energy use within a climate context and to identify a design direction. Note that you may need to refer to different software may not be the one used to develop complete the whole building energy simulations necessary for LEED certification.
Energy modeling can inform your project team from the start of design. Early on, review site climate data—such as temperature, humidity and wind, available from most energy software—as a team. Evaluate the site context and the microclimate, noting the effects of neighboring buildings, bodies of water, and vegetation. Estimate the distribution of energy across major end uses (such as space heating and cooling, lighting, plug loads, hot water, and any additional energy uses), targeting high-energy-use areas to focus on during design.
Use a preliminary energy use breakdown like this one to identify target areas for energy savings.Perform preliminary energy modeling in advance of the schematic design phase kick-off meeting or design charrette. The energy use breakdown can help identify targets for energy savings and point toward possible alternatives.
For existing buildings, the baseline energy model can reflect the pre-renovation features like rather than a minimally ASHRAE-compliant building. This will help you achieve additional savings in comparison with the baseline.
Projects generating renewable energy onsite should use Option 1 to best demonstrate EAp2 compliance and maximize points under EAc1. Other options are possible but won’t provide as much benefit. Like any other project, model the baseline case as a system compliant with ASHRAE 90.1-2007, using grid-connected electricity, and the design case is an “as-designed” system also using grid-connected electricity. You then plug in 100% onsite renewable energy in the final energy-cost comparison table, as required by the performance rating method (PRM) or the modeling protocol of ASHRRAE 90.1 2007, Appendix G. (Refer to the sample PRM tables in the Documentation Toolkit for taking account of onsite renewable energy.
LEED divides energy-using systems into two categories:
The energy model itself will not account for any change in plug loads from the baseline case, even if your project is making a conscious effort to purchase Energy Star or other efficient equipment. Any improvement made in plug loads must be documented separately, using the exceptional calculation methodology (ECM), as described in ASHRAE 90.1-2007. These calculations determine the design case energy cost compared to the baseline case. They are included in the performance rating method (PRM) table or directly in the baseline and design case model.
Besides energy modeling, you may need to use the exceptional calculation methodology (ECM) when any of the following situations occur:
Some energy-modeling software tools have a daylight-modeling capability. Using the same model for both energy and IEQc8.1: Daylight and Views—Daylight can greatly reduce the cost of your modeling efforts.
Provide a copy of the AEDG for office, retail, or warehouse, as applicable, to each team member as everyone, including the architect, mechanical and electrical engineers, lighting designer, and commissioning agents, are responsible for ensuring compliance. These are available to download free from the ASHRAE website. (See Resources.)
Find your climate zone before attempting to meet any detailed prescriptive requirements. Climate zones vary by county, so be sure to select the right one. (See the Documentation Toolkit for a list of climate zones by county.)
Develop a checklist of all requirements, and assign responsible team members to accomplish them. Hold a meeting to walk the team through the AEDG checklist for your project’s climate zone. Clarify specific design goals and prescriptive requirements in the OPR for EAp1: Fundamental Commissioning.
Early access to the AEDG by each team member avoids last-minute changes that can have cascading, and costly, effects across many building systems.
The AEDG prescriptive requirements include:
If your project team is not comfortable following these guidelines, consider switching to Option 1, which gives you more flexibility.
Although Option 2 is generally lower cost during the design phase than energy modeling, the compliance path is top heavy—it requires additional meeting time upfront for key design members.
Provide a copy of the New Buildings Institute Advanced Buildings: Core Performance Guide to each team member. The guide is available to download free from the NBI website. (See Resources.)
The guide provides practical design assistance that can be used throughout the design process.
Walk your team through the project checklist to clarify design goals and prescriptive requirements.
The guide provides an outline for approaching an energy-efficient design, in addition to a list of prescriptive measures. The first of its three sections emphasizes process and team interaction rather than specific building systems or features. Advise the owner to read through the guide in order to understand what is required of the architect and engineers.
Section 1 in the guide focuses on best practices that benefit the project during the pre-design and schematic design stages, such as analyzing alternative designs and writing the owner’s project requirements (OPR).
Section 2 of the Core Performance Guide describes architectural, lighting, and mechanical systems to be included. Section 3 is not required for EAp2 but includes additional opportunities for energy savings that can earn EAc1 points.
The guide mandates that your team develop a minimum of three different design concepts to select from for best energy use.
Though they can be a little daunting at first glance, a majority of the guide’s requirements overlap with other LEED credits, such as EAp1: Fundamental Commissioning, IEQp1: Minimum Indoor Air Quality Performance, and IEQc6.1: Controllability of Systems—Lighting Controls.
This compliance path is top-heavy due to upfront consultant time, but it provides adequate structure to ensure that your project is in compliance with the prerequisite requirements. For some projects it may be less expensive to pursue than Option 1.
The owner should now have finalized the OPR with the support of the architect, as part of the commissioning credits EAp1 and EAc3. The goals identified here will help your team identify energy-reduction and occupant-comfort strategies.
Consider a broad range of energy-efficiency strategies and tools, including passive solar, daylighting, cooling-load reduction, and natural ventilation to reduce heating and cooling loads.
Develop the basis of design (BOD) document in conjunction with your mechanical engineer and architect for EAp1: Fundamental Commissioning, noting key design parameters to help strategize design direction as outlined in the OPR.
The OPR and BOD serve the larger purpose of documenting the owner’s vision and your team’s ideas to meet those goals. The BOD is intended to be a work-in-progress and should be updated at all key milestones in your project. Writing the document gives you an opportunity to capture the owner’s goals, whether just to meet the prerequisite or to achieve points under EAc1.
Confirm that your chosen compliance path is the most appropriate for your project, and make any changes now. Following a review with the design team and owner, ensure that everyone is on board with contracting an energy modeler for Option 1 or meeting all the prescriptive requirements under Options 2 or 3.
Sometimes teams change from Option 1 to Options 2 or 3 very late in the design phase for various reasons including not realizing the cost of energy modeling. Making that change is risky, though: the prescriptive paths are all-or-nothing—you must comply with every item, without exception. Evaluate each requirement and consult with the contractor and estimator to ensure the inclusion of all activities within project management.
To avoid costly, last-minute decisions, develop a comprehensive, component-based cost model as a decision matrix for your project. The model will help establish additional cost requirements for each energy conservation measure. It will also illustrate cost reductions from decreased equipment size, construction rendered unnecessary by energy conservation measures, and reduced architectural provisions for space and equipment access. (See the Documentation Toolkit for an example.)
Use envelope design and passive strategies to reduce the heating and cooling loads prior to detailed design of HVAC systems. Passive strategies can reduce heating and cooling loads, giving the engineer more options, including smaller or innovative systems.
Load reduction requires coordinated efforts by all design members including the architect, lighting designer, interior designer, information-technology manager, and owner.
Involving facilities staff in the design process can further inform key design decisions, helping ensure successful operation and low maintenance costs.
Encourage your design team to brainstorm design innovations and energy-reduction strategies. This provides a communication link among team members so they can make informed decisions.
More energy-efficient HVAC equipment can cost more relative to conventional equipment. However, by reducing heating and cooling loads through good passive design, the mechanical engineer can often reduce the size and cost of the system. Reduced system size can save money through:
Review case studies of similar energy-efficient buildings in the same climate to provide helpful hints for selecting energy-efficiency measures. For example, a building in a heating-dominated climate can often benefit from natural ventilation and free cooling during shoulder seasons. (See Resources for leading industry journals showcasing success stories around the country and internationally.)
The relationship between first costs and operating costs can be complex. For example, more efficient windows will be more expensive, but could reduce the size and cost of mechanical equipment. A more efficient HVAC system may be more expensive, but will reduce operating costs. Play around with variables and different strategies to get the right fit for the building and the owner’s goals as stated in the OPR.
Review and confirm compliance with the mandatory requirements of all the relevant sections of ASHRAE 90.1-2007
Trust your project’s energy modeling task to a mechanical firm with a proven track record in using models as design tools, and experience with your building type.
Contract an energy modeling team for the project. These services may be provided by the mechanical engineering firm on the design team or by an outside consultant. Software used for detailed energy use analysis and submitted for final LEED certification must be accepted by the regulatory authority with jurisdiction, and must comply with paragraph G2.2 of ASHRAE Standard 90.1-2007. Refer to Resources for a list of Department of Energy approved energy-analysis software that may be used for LEED projects.
Design team members, including the architect and mechanical engineer at a minimum, need to work together to identify a percentage improvement goal for project energy use over the ASHRAE 90.1-2007-compliant baseline model. The percentage should be at least 10% to meet the prerequisite.
Plan on initiating energy modeling during the design process, and use it to inform your design—preferably executing several iterations of the design as you improve the modeled energy performance.
Ask the modeling consultant to develop an annual energy-use breakdown—in order to pick the “fattest” targets for energy reduction. A typical energy-use breakdown required for LEED submission and ASHRAE protocol includes:
Identify critical areas in which to reduce loads. For example, in a data center, the plug loads are the largest energy load. Small changes in lighting density might bring down the energy use but represent only a small fraction of annual energy use.
Don't forget that LEED (following ASHRAE) uses energy cost and not straight energy when it compares your design to a base case. That's important because you might choose to use a system that burns natural gas instead of electricity and come out with a lower cost, even though the on-site energy usage in kBtus or kWhs is higher. Generally you have to specify the same fuel in your design case and in the base case, however, so you can't simply switch fuels to show a cost savings
Explore and analyze design alternatives for energy use analyses to compare the cost-effectiveness of your design choices. For example, do you get better overall performance from a better window or from adding a PV panel? Will demand-control ventilation outperform increased ceiling insulation?
Simple, comparative energy analyses of conceptual design forms are useful ways to utilize an energy model at this stage. Sample scenarios include varying the area of east-facing windows and looking at 35% versus 55% glazing. Each scenario can be ranked by absolute energy use to make informed decisions during the design stage.
If your project is using BIM software, the model can be plugged into the energy analysis software to provide quick, real-time results and support better decisions.
Model development should be carried out following the PRM from ASHRAE 90.1-2007, Appendix G, and the LEED 2009 Design and Construction Reference Guide, Table in EAc1. In case of a conflict between ASHRAE and LEED guidelines, follow LEED.
Projects using district energy systems have special requirements. For EAp2, the proposed building must achieve the 10% energy savings without counting the effects of the district generation system. To earn points in EAc1 you can take advantage of the district system’s efficiency, but you have to run the energy model again to claim those benefits (see EAc1 for details).
While you could run the required energy model at the end of the design development phase, simply to demonstrate your prerequisite compliance, you don’t get the most value that way in terms of effort and expense. Instead, do it early in the design phase, and run several versions as you optimize your design. Running the model also gives you an opportunity to make improvements if your project finds itself below the required 10% savings threshold.
The baseline model is the designed building with mechanical systems specified in ASHRAE 90.1-2007, Appendix G, for the specific building type, with a window-to-wall ratio at a maximum of 40%, and minimally code-compliant specifications for the envelope, lighting, and mechanical components. It can be developed as soon as preliminary drawings are completed. The baseline is compared to the design case to provide a percentage of reduction in annual energy use. To avoid any bias from orientation, you need to run the baseline model in each of the four primary directions, and the average serves as your final baseline figure.
The design-case is modeled using the schematic design, orientation, and proposed window-to-wall ratio—¬the model will return design-case annual energy costs. Earn points by demonstrating percentage reductions in annual energy costs from the design to the baseline case. EAp2 is achieved if the design case is 10% lower than the baseline in new construction (or 5% less in existing building renovations).
Provide as much project and design detail to the modeler as possible. A checklist is typically developed by the energy modeler, listing all the construction details of the walls, roof, slabs, windows, mechanical systems, equipment efficiencies, occupancy load, and schedule of operations. Any additional relevant information or design changes should be brought to the modeler’s attention as soon as possible. The more realistic the energy model is, the more accurate the energy use figure, leading to better help with your design.
Invite energy modelers to project meetings. An experienced modeler can often assist in decision-making during design meetings, even without running complete models each time.
All known plug loads must be included in the model. The baseline and design-case models assume identical plug loads. If your project is deliberately attempting to reduce plug loads, demonstrate this by following the exceptional calculation method (ECM), as described in ASHRAE 90.1-2007, G2.5. Incorporate these results in the model to determine energy savings.
For items outside the owner’s control—like lighting layout, fans and pumps—the parameters for the design and baseline models must be identical.
It can take anywhere from a few days to a few weeks to generate meaningful energy modeling results. Schedule the due dates for modeling results so that they can inform your design process.
Review the rate structure from your electrical utility. The format can inform your team of the measures likely to be most effective in reducing energy costs, especially as they vary over season, peak load, and additional charges beyond minimum energy use.
Performing a cost-benefit analysis in conjunction with energy modeling can determine payback times for all the energy strategies, helping the iterative design process.
Using energy modeling only to check compliance after the design stage wastes much of the value of the service, and thus your investment.
The architect and mechanical engineer should carefully read the applicable ASHRAE Advanced Energy Design Guide for office, warehouse, or retail projects, as applicable.
Keep the owner abreast of the design decisions dictated by the standard. Fill in the team-developed checklist, within the climate zone table’s prescribed requirements, with appropriate envelope improvements, system efficiencies, and a configuration that meets the standard requirements.
As a prescriptive path, this option relies heavily on following the requirement checklist, which is used throughout the design process to track progress. To assist design development, provide all critical team members—not limited to the architect, mechanical and electrical engineers, and lighting designer—with a checklist highlighting their appointed tasks.
The architect, mechanical engineer, and lighting designer need to discuss each requirement and its design ramifications. Hold these meetings every six to eight weeks to discuss progress and make sure all requirements are being met.
Confirm that your project team is comfortable with following all the prescribed requirements. If not, switch to Option 1: Whole Building Energy Simulation.
The LEED Online credit form does not specify how to document each prescriptive requirement because they are so different for each project; it only requires a signed confirmation by the MEP for meeting AEDG requirements. You still have to provide documentation. Submit your checklist of requirements, and supporting information for each item, through LEED Online to make your case. If your project fails to meet even one requirement, it will fail to earn the prerequisite, thus jeopardizing LEED certification.
Although energy modeling consultant costs are avoided by this option, additional staff time will be required to document and track compliance status, as compared with conventional projects.
Energy efficiency measures prescribed by the guide can be perceived as additional costs in comparison with conventional projects. However, they are easy to implement and are cost-effective pn the whole.
Become familiar with the Core Performance Guide early in the design phase to know the multiple requirements and all requisite documents.
Note that the guide demands additional time, attention, and integrated process from the design team as compared to conventional projects. It’s not just a list of prescriptive requirements, but a prescribed process for achieving energy efficiency goals. LEED Online documentation requires proof of all steps outlined in Sections 1 and 2, including three conceptual design options and meeting minutes. The project manager, architect, and mechanical engineer should read the complete Core Performance Guide carefully to know beforehand the prescriptive requirements in Sections 1 and 2.
The project manager must take responsibility for ensuring that the requirement checklist is on track.
For Section 3, the design team needs to identify three or more of the listed strategies as possible targets for the project.
Create a checklist of requirements and assign a responsible party to each item.
The Core Performance Guide requires an integrated design contributed by the architect, mechanical and electrical engineers, and lighting designer. The project manager must take responsibility for shepherding and documenting the collaborative process to demonstrate compliance.
A long documentation list can be overwhelming for your team, so create a detailed checklist with tasks delegated to individual team members, allowing each member to focus on assigned tasks. The checklist can function as a status tracking document and, finally, the deliverable for LEED Online.
The architect and engineer, and other project team members, continue to develop a high-performance building envelope with efficient mechanical and lighting systems.
Constant communication and feedback among project team members, owner, and if possible, operational staff, during design development can minimize construction as well as operational costs and keep your project on schedule.
If you change or go through value-engineering on any specifications, such as the solar-heat gain coefficient of glazing, for example, be aware of impacts on mechanical system sizing. Making changes like this might not pay off as much as it first appears.
Consider using building information modeling (BIM) tools to keep design decisions up to date and well documented for all team members.
Schedule delays can be avoided if all team members share their ideas and update documents during the design development process.
The modeler completes the energy analysis of the selected design and system and offers alternative scenarios for discussion. The modeler presents the energy cost reduction results to the team, identifying the LEED threshold achieved.
It’s helpful for the energy modeling report to include a simple payback analysis to assist the owner in making an informed decision on the operational savings of recommended features.
The architect and HVAC engineer should agree on the design, working with the cost estimator and owner.
Demonstrating reductions in non-regulated loads requires a rigorous definition of the baseline case. The loads must be totally equivalent, in terms of functionality, to the proposed design case. For example, reducing the number of computers in the building does not qualify as a legitimate reduction in non-regulated loads. However, the substitution of laptops for desktop computers, and utilization of flat-screen displays instead of CRTs for the same number of computers, may qualify as a reduction.
Residential and hospitality projects that use low-flow showers, lavatories, and kitchen sinks (contributing to WEp1) benefit from lower energy use due to reduced overall demand for hot water. However, for energy-savings calculations, these are considered process loads that must be modeled as identical in baseline and design cases, or you have the choice of demonstrating the savings with ECM for process loads.
Perform daylight calculations in conjunction with energy modeling to balance the potentially competing goals of more daylight versus higher solar-heat gain resulting in high cooling loads.
If your project is pursuing renewable energy, the energy generated is accounted for by using the PRM. These results provide information about whether the energy is contributing to EAc2: Onsite Renewable Energy.
A cost-benefit analysis can help the owner understand the return on investment of big-ticket, energy-conserving equipment that lowers operating energy bills with a quick payback.
Complete at least half of the energy modeling effort by the end of the design development stage. Help the design team to finalize strategy through intensive, early efforts in energy modeling. Once the team has a design direction, the modeler can develop a second model during the construction documents phase for final confirmation.
If pursuing ECM for non-regulated loads, calculate energy saving for each measure separately if you are, for example, installing an energy-efficient elevator instead of a typical one so that the reduction would contribute to total building energy savings. Calculate the anticipated energy use of the typical elevator in kBTUs or kWh. Using the same occupancy load, calculate the energy use of the efficient elevator. Incorporate the savings into design case energy use within the PRM. Refer to the ECM strategy for detailed calculation guidelines.
Ensure that all prescriptive requirements are incorporated into the design by the end of the design development stage.
Revisit the Advanced Energy Design Guides (AEDG) checklist to ensure that the design meets the prescriptive requirements.
The mechanical engineer, lighting consultant, and architect revisit the checklist for an update on the requirements and how they are being integrated into the design. All prescriptive requirements should be specifically incorporated into the design by the end of the design development phase.
The mechanical engineer and architect track the status of each requirement.
While the LEED Online credit form does not require detailed documentation for each Core Performance Guide requirement, it is important that each item be documented as required and reviewed by the rest of the team to confirm compliance, especially as further documentation may be requested by during review. Your design team should work with the owner to identify cost-effective strategies from Section 3 that can be pursued for the project.
Construction documents clearly detail the architectural and mechanical systems that address energy-efficiency strategies.
Confirm that specifications and the bid package integrate all equipment and activities associated with the project.
If the project goes through value engineering, refer to the OPR and BOD to ensure that no key comfort, health, productivity, daylight, or life-cycle cost concerns are sacrificed.
During the budget estimating phase, the project team may decide to remove some energy-saving strategies that have been identified as high-cost items during the value-engineering process. However, it is very important to help the project team understand that these so-called add-ons are actually integral to the building’s market value and the owner’s goals.
Removing an atrium, for example, due to high cost may provide additional saleable floor area, but may also reduce daylight penetration while increasing the lighting and conditioning loads.
Although this prerequisite is a design-phase submittal, it may make sense to submit it, along with EAc1, after construction. Your project could undergo changes during construction that might compel a new run of the energy model to obtain the latest energy-saving information. Waiting until the completion of construction ensures that the actual designed project is reflected in your energy model.
Create a final energy model based completely on construction document drawings—to confirm actual energy savings as compared to ASHRAE 90.1-2007 requirements. An energy model based on the construction documents phase will provide realistic energy-cost savings and corresponding LEED points likely to be earned.
Make sure the results fit the LEED Online credit form requirements. For example, the unmet load hours have to be less than 300 and process loads will raise a red flag if they’re not approximately 25%. If any of the results are off mark, take time to redo the model. Time spent in design saves more later on in the LEED review process.
Finalize all design decisions and confirm that you’ve met all of the prescriptive requirements. Your team must document the checklist with relevant project drawings, including wall sections, specifications, and the MEP drawing layout.
Value engineering and other factors can result in design changes that eliminate certain energy features relevant to the prerequisite. As this compliance path is prescriptive, your project cannot afford to drop even one prescribed item.
Value engineering and other factors can result in design changes that eliminate certain energy features relevant to the credit. As this compliance path is prescriptive, your project cannot afford to drop even one listed item. Although perceived as high-cost, prescriptive requirements lower energy costs during operation and provide a simple payback structure.
The architect and mechanical engineer review the shop drawings to confirm the installation of the selected systems.
The commissioning agent and the contractor conduct functional testing of all mechanical equipment in accordance with EAp1: Fundamental Commissioning and EAc3: Enhanced Commissioning.
Find your Energy Star rating with EPA’s Target Finder tool if your building type is in the database. Input your project location, size, and number of occupants, computers, and kitchen appliances. The target may be a percentage energy-use reduction compared to a code-compliant building, or “anticipated energy use” data from energy model results. Add information about your fuel use and rate, then click to “View Results.” Your Target Finder score should be documented at LEED Online.
Plan for frequent site visits by the mechanical designer and architect during construction and installation to make sure construction meets the design intent and specifications.
Emphasize team interaction and construction involvement when defining the project scope with key design team members. Contractor and designer meetings can help ensure correct construction practices and avoid high change-order costs for the owner.
Subcontractors may attempt to add a premium during the bidding process for any unusual or unknown materials or practices, so inform your construction bidders of any atypical design systems at the pre-bid meeting.
The energy modeler ensures that any final design changes have been incorporated into the updated model.
Upon finalizing of the design, the responsible party or energy modeler completes the LEED Online submittal with building design inputs and a PRM result energy summary.
Although EAp2 is a design phase submittals, it may make sense to submit it (along with EAc1) after construction. Your project could undergo changes during construction that might require a new run of the energy model. Waiting until the completion of construction ensures that your actual designed project is reflected. On the other hand, it gives you less opportunity to respond to questions that might come up during a LEED review.
Include supporting documents like equipment cut sheets, specifications and equipment schedules to demonstrate all energy efficiency measures claimed in the building.
It common for the LEED reviewers to make requests for more information. Go along with the process—it doesn’t mean that you’ve lost the credit. Provide as much information for LEED Online submittal as requested and possible.
The design team completes the LEED Online documentation, signing off on compliance with the applicable AEDG, and writing the narrative report on the design approach and key highlights.
During LEED submission, the project team needs to make an extra effort to support the prerequisite with the completed checklist and the required documents. Although the LEED rating system does not list detailed documentation, it is best practice to send in supporting documents for the prescriptive requirements from the AEDG. The supporting documents should include relevant narratives, wall sections, mechanical drawings, and calculations.
Although the LEED Online sign-off does not include a checklist of AEDG requirements, it assumes that the team member is confirming compliance with all detailed requirements of the guide.
The design team completes the LEED Online credit form, signing off on compliance with the Core Performance Guide, and writing the narrative report on the design approach and key highlights.
During LEED submission, your project team needs to make an extra effort to support the prerequisite with the completed checklist and the required documents. Although not every requirement may be mentioned in the LEED documentation, the supporting documents need to cover all requirements with narratives, wall sections, mechanical drawings, and calculations.
Many of this option’s compliance documents are common to other LEED credits or design documents, thus reducing duplicated efforts.
Develop an operations manual with input from the design team in collaboration with facility management and commissioning agent if pursuing EAc3: Enhanced Commissioning.
The benefit of designing for energy efficiency is realized only during operations and maintenance. Record energy use to confirm that your project is saving energy as anticipated. If you are not pursuing EAc5: Measurement and Verification, you can implement tracking procedures such as reviewing monthly energy bills or on-the-spot metering.
Some energy efficiency features may require special training for operations and maintenance personnel. For example, cogeneration and building automation systems require commissioning and operator training. Consider employing a trained professional to aid in creating operation manuals for specialty items.
Energy-efficiency measures with a higher first cost often provide large savings in energy use and operational energy bills. These credit requirements are directly tied to the benefits of efficient, low-cost operations.
Excerpted from LEED 2009 for New Construction and Major Renovations
To establish the minimum level of energy efficiency for the proposed building and systems to reduce environmental and economic impacts associated with excessive energy use.
Demonstrate a 10% improvement in the proposed building performance rating for new buildings, or a 5% improvement in the proposed building performance rating for major renovations to existing buildings, compared with the baseline building performanceBaseline building performance is the annual energy cost for a building design, used as a baseline for comparison with above-standard design. rating.
Calculate the baseline building performance rating according to the building performance rating method in Appendix G of ANSI/ASHRAE/IESNA Standard 90.1-2007 (with errata but without addenda1) using a computer simulation model for the whole building project. Projects outside the U.S. may use a USGBC approved equivalent standard2.
Appendix G of Standard 90.1-2007 requires that the energy analysis done for the building performance rating method include all energy costs associated with the building project. To achieve points using this credit, the proposed design must meet the following criteria:
For the purpose of this analysis, process energy is considered to include, but is not limited to, office and general miscellaneous equipment, computers, elevators and escalators,kitchen cooking and refrigeration, laundry washing and drying, lighting exempt from the lighting power allowance (e.g., lighting integral to medical equipment) and other (e.g., waterfall pumps).
Regulated (non-process) energy includes lighting (for the interior, parking garage, surface parking, façade, or building grounds, etc. except as noted above), heating, ventilation and air conditioning (HVAC) (for space heating, space cooling, fans, pumps, toilet exhaust, parking garage ventilation, kitchen hood exhaust, etc.), and service water heating for domestic or space heating purposes.
Process loads must be identical for both the baseline building performance rating and the proposed building performance rating. However, project teams may follow the exceptional calculation method (ANSI/ASHRAE/IESNA Standard 90.1-2007 G2.5) or USGBC approved equivalent to document measures that reduce process loads. Documentation of process load energy savings must include a list of the assumptions made for both the base and the proposed design, and theoretical or empirical information supporting these assumptions.
Projects in California may use Title 24-2005, Part 6 in place of ANSI/ASHRAE/IESNA Standard 90.1-2007 for Option 1.
Comply with the prescriptive measures of the ASHRAE Advanced Energy Design Guide appropriate to the project scope, outlined below. Project teams must comply with all applicable criteria as established in the Advanced Energy Design Guide for the climate zoneOne of five climatically distinct areas, defined by long-term weather conditions which affect the heating and cooling loads in buildings. The zones were determined according to the 45-year average (1931-1975) of the annual heating and cooling degree-days (base 65 degrees Fahrenheit). An individual building was assigned to a climate zone according to the 45-year average annual degree-days for its National Oceanic and Atmospheric Administration (NOAA) Division. in which the building is located. Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone.
The building must meet the following requirements:
Comply with the prescriptive measures identified in the Advanced Buildings™ Core Performance™ Guide developed by the New Buildings Institute. The building must meet the following requirements:
Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone.
1Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.
2 Projects outside the U.S. may use an alternative standard to ANSI/ASHRAE/IESNA Standard 90.1-2007 if it is approved by USGBC as an equivalent standard using the process located at www.usgbc.org/leedisglobal
Design the building envelope and systems to meet baseline requirements. Use a computer simulation model to assess the energy performance and identify the most cost-effective energy efficiency measures. Quantify energy performance compared with a baseline building.
If local code has demonstrated quantitative and textual equivalence following, at a minimum, the U.S. Department of Energy (DOE) standard process for commercial energy code determination, then the results of that analysis may be used to correlate local code performance with ANSI/ASHRAE/IESNA Standard 90.1-2007. Details on the DOE process for commercial energy code determination can be found at http://www.energycodes.gov/implement/ determinations_com.stm.
1 Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.
2 Projects outside the U.S. may use an alternative standard to ANSI/ASHRAE/IESNA Standard 90.1‐2007 if it is approved by USGBC as an equivalent standard using the process located at www.usgbc.org/leedisglobal
This database shows state-by-state incentives for energy efficiency, renewable energy, and other green building measures. Included in this database are incentives on demand control ventilation, ERVs, and HRVs.
Useful web resource with information on local/regional incentives for energy-efficiency programs.
ACEEE is a nonprofit organization dedicated to advancing energy efficiency through technical and policy assessments; advising policymakers and program managers; collaborating with businesses, public interest groups, and other organizations; and providing education and outreach through conferences, workshops, and publications.
The New Buildings Institute is a nonprofit, public-benefits corporation dedicated to making buildings better for people and the environment. Its mission is to promote energy efficiency in buildings through technology research, guidelines, and codes.
The Building Energy Codes program provides comprehensive resources for states and code users, including news, compliance software, code comparisons, and the Status of State Energy Codes database. The database includes state energy contacts, code status, code history, DOE grants awarded, and construction data. The program is also updating the COMcheck-EZ compliance tool to include ANSI/ASHRAE/IESNA 90.1–2007. This compliance tool includes the prescriptive path and trade-off compliance methods. The software generates appropriate compliance forms as well.
Research center at RPI provides access to a wide range of daylighting resources, case studies, design tools, reports, publications and more.
International association of energy modelers with various national and local chapters.
Non-profit organization aiming at design community to increase collaboration for designing energy efficient buildings.
The Low Impact Hydropower Institute is a non-profit organization and certification body that establishes criteria against which to judge the environmental impacts of hydropower projects in the United States.
The Building Technologies Program (BTP) provides resources for commercial and residential building components, energy modeling tools, building energy codes, and appliance standards including the Buildings Energy Data Book, High Performance Buildings Database and Software Tools Directory.
This website discusses the step-by-step process for energy modeling.
This online resource, supported by Natural Resources Canada, presents energy-efficient technologies, strategies for commercial buildings, and pertinent case studies.
This website is a comprehensive resource for U.S. Department of Energy information on energy efficiency and renewable energy and provides access to energy links and downloadable documents.
Information on cogenerationThe simultaneous production of electric and thermal energy in on-site, distributed energy systems; typically, waste heat from the electricity generation process is recovered and used to heat, cool, or dehumidify building space. Neither generation of electricity without use of the byproduct heat, nor waste-heat recovery from processes other than electricity generation is included in the definition of cogeneration., also called combined heat and power, is available from EPA through the CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. Partnership. The CHP Partnership is a voluntary program seeking to reduce the environmental impact of power generation by promoting the use of CHP. The Partnership works closely with energy users, the CHP industry, state and local governments, and other clean energy stakeholders to facilitate the development of new projects and to promote their environmental and economic benefits.
Free download of AHSRAE energy savings guide, use for Option 2.
Research warehouse for strategies and case studies of energy efficiency in buildings.
An online window selection tool with performance characteristics.
This website lays out design process for developing an energy efficient building.
This website discusses ways to improve design for lower energy demand as they relate to the AIA 2030 challenge.
This website includes discussion of design issues, materials and assemblies, window design decisions and case studies.
This site lists multiple web-based and downloadable tools that can be used for energy analyses.
This database is maintainted by the California Energy Commission and lists resources related to energy use and efficiency.
Energy design tools are available to be used for free online or available to download.
This website lists performance characteristics for various envelope materials.
This is an online forum of discussion for energy efficiency, computer model software users.
Target Finder is a goal-setting tool that informs your design team about their project’s energy performance as compared to a national database of projects compiled by the EPA.
This directory provides information on 406 building software tools for evaluating energy efficiency, renewable energy, and sustainability in buildings.
Weather data for more than 2100 locations are available in EnergyPlus weather format.
Weather data for U.S. and Non-U.S. locations in BIN format.
A web-based, free content project by IBPSA-USA to develop an online compendium of the domain of Building Energy Modeling (BEM). The intention is to delineate a cohesive body of knowledge for building energy modeling.
A guide for achieving energy efficiency in new commercial buildings, referenced in the LEED energy credits.
This manual is a strategic guide for planning and implementing energy-saving building upgrades. It provides general methods for reviewing and adjusting system control settings, plus procedures for testing and correcting calibration and operation of system components such as sensors, actuators, and controlled devices.
This document is USGBC’s second (v2.0) major release of guidance for district or campus thermal energy in LEED, and is a unified set of guidance comprising the following an update to the original Version 1.0 guidance released May 2008 for LEED v2.x and the initial release of formal guidance for LEED v2009.
This manual offers guidance to building energy modelers, ensuring technically rigorous and credible assessment of energy performance of commercial and multifamily residential buildings. It provides a streamlined process that can be used with various existing modeling software and systems, across a range of programs.
Chapter 19 is titled, “Energy Estimating and Modeling Methods”. The chapter discusses methods for estimating energy use for two purposes: modeling for building and HVAC system design and associated design optimization (forward modeling), and modeling energy use of existing buildings for establishing baselines and calculating retrofit savings (data-driven modeling).
Required reference document for DES systems in LEED energy credits.
ASHRAE writes standards for the purpose of establishing consensus for: 1) methods of test for use in commerce and 2) performance criteria for use as facilitators with which to guide the industry.
Energy statistics from the U.S. government.
This guide includes instructional graphics and superior lighting design solutions for varying types of buildings and spaces, from private offices to big box retail stores.
This website offers information on energy efficiency in buildings, highlighting success stories, breakthrough technology, and policy updates.
Bimonthly publication on case studies and new technologies for energy efficiency in commercial buildings.
AIA publication highlighting local and state green building incentives.
2008 guidelines and performance goals from the National Science and Technology Council.
Information about energy-efficient building practices available in EDR's Design Briefs, Design Guidelines, Case Studies, and Technology Overviews.
DOE tools for whole building analyses, including energy simulation, load calculation, renewable energy, retrofit analysis and green buildings tools.
This is a computer program that predicts the one-dimensional transfer of heat and moisture.
DesignBuilder is a Graphical User Interface to EnergyPlus. DesignBuilder is a complete 3-D graphical design modeling and energy use simulation program providing information on building energy consumption, CO2Carbon dioxide emissions, occupant comfort, daylighting effects, ASHRAE 90.1 and LEED compliance, and more.
IES VE Pro is an integrated computing environment encompassing a wide range of tasks in building design including model building, energy/carbon, solar, light, HVAC, climate, airflow, value/cost and egress.
Use this checklist of prescriptive requirements (with sample filled out) to have an at-a-glance picture of AEDG requirements for Option 2, and how your project is meeting them.
This spreadsheet lists all the requirements for meeting EAp2 – Option 3 and and EAc1 – Option 3. You can review the requirements, assign responsible parties and track status of each requirement through design and construction.
Sometimes the energy simulation software being used to demonstrate compliance with Option 1 doesn't allow you to simulate key aspects of the design. In this situation you'll need to write a short sample narrative, as in these examples, describing the situation and how it was handled.
In your supporting documentation, include spec sheets of equipment described in the Option 1 energy model or Options 2–3 prescriptive paths.
This is a sample building energy performance and cost summary using the Performance Rating Method (PRM). Electricity and natural gas use should be broken down by end uses including space heating, space cooling, lights, task lights, ventilation fans, pumps, and domestic hot water, at the least.
Option 1 calculates savings in annual energy cost, but utility prices may vary over the course of a year. This sample demonstrates how to document varying electricity tariffs.
This graph, for an office building design, shows how five overall strategies were implemented to realize energy savings of 30% below an ASHRAE baseline. (From modeling conducted by Synergy Engineering, PLLC.)
The climate zones shown on this Department of Energy map are relevant to all options for this credit.
This spreadsheet, provided here by 7group, can be used to calculate the fan volume and fan power for Appendix G models submitted for EAp2/EAc1. Tabs are included to cover both ASHRAE 90.1-2004 and 90.1-2007 Appendix G methodologies.
The following links take you to the public, informational versions of the dynamic LEED Online forms for each NC-2009 EA credit. You'll need to fill out the live versions of these forms on LEED Online for each credit you hope to earn.
Version 4 forms (newest):
Version 3 forms:
These links are posted by LEEDuser with USGBC's permission. USGBC has certain usage restrictsions for these forms; for more information, visit LEED Online and click "Sample Forms Download."
Documentation for this credit can be part of a Design Phase submittal.
I also read the discussion above.
Now things are clear!
Thanks a lot!
I just didn't understand one matter. The supply air volume calculated according to section G220.127.116.11 is used to calculate the total fan power for baseline system design, which reflects the sum of power modeled for supply, exhaust, return and relief fans.
Though, in section G18.104.22.168, it is mentioned that "if return or relief fans are specified in the proposed design, the baseline building design shall also be modeled with fans serving the same functions...". But, weren't they already accounted for in the formula of section G22.214.171.124? Is it necessary any additional modeling?
The second part refers to the sizing of the baseline supply air quantity. Use G126.96.36.199 to determine the quantity of air. The fan power for all fans associated with the HVAC systems is accounted for in G188.8.131.52 so no need to add any fan power.
In section G184.108.40.206 it is specified that "system fan eletrical power for supply,..., shall be calculated using the following formulas:"
Then, it is presented some formulas indicating the fan system input and fan system motor nameplate.
Just to confirm, in the simulation model, the energy consumption related to these fans shall be calculated based on the fan system motor nameplate, right? Or should it be calculated based on fan system input?
The baseline is calculated based on the auto-sized supply air cfm. There is a spreadsheet tool that does these calculations under the resources section at the top of this page. The baseline would not have a motor nameplate because the fans do not exist.
The proposed is calculated based on the actual design.
I understand that the baseline fan power is calculated based on the supply airflow rate, whose formula is presented in Table G220.127.116.11.
Though, in section G18.104.22.168, based on the value previously calculated, we calculate the Pfan, which would correspond to the eletric power to fan motor.
My question is, in the simulation model, should I use the value calculated through the Table or the Pfan value?
Hard for me to say how it gets modeled as it could be software specific.
The value calculated in the table gives you the bhp which is then used to calculated Pfan. What are your options for inputting this data in the software you are using?
For LEED the reviewer will ideally want to see the kW of the baseline fans.
This question came up and I want to refresh my memory.
The baseline model must ALWAYS (baring DV) have the same ODA as the Proposed Design...also when the Proposed Design is applying for the increased ventilation credit. Right?
Yes the baseline OA should be identical to the proposed unless the proposed has DCV.
I have a school that is approximately 180,000 sqft. I'm able to take exceptions for a large gym that is approximately 40,000 sqft and use PSZ in this area. Should I then use Rooftop Dx w/ VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. Reheat because the remainder of the facility is less thant 150,000 sqft? Or should I stick with a chilled water system because the total facility is over 150,000 sqft?
When you apply an exception from G3.1.1 the square footage of that area comes off the total which is then used to re-enter Table G3.1.1A. This is how that issue is currently being applied in LEED reviews as I understand it.
Personally I do not agree with this method. I think you should enter the table with the full building square footage, select the appropriate system, then apply an exceptions without it affecting the predominant condition. This way the predominant condition determines the majority system and the exception gets applied to only the appropriate spaces.
I would love to hear from the forum - which method sounds right to you?
I've contacted ASHRAE to get their interpretation of this issue. I'm hoping to have word from the subcommittee chair soon. I personally feel that the intent of the exception is to divide spaces and assign systems to those spaces as they would normally be designed. So that a space with a different occupancy, operating schedule, or peak thermal load isn't lumped in one system together. Therefore each space should be considered separately with regard to Table G3.1.1A. I know you're saying the predominant space is the only one that follows the table, and all others follow the exception (meaning CAV DX). But this doesn't make sense to me either. I can understand small areas being designated as CAV DX, like the examlpe says a Server Room. But just because a space is 5,000 sqft less than another (which allows for "games" to be played in boundary lines) doesn't mean than it should be CAV DX. Would you every make an office CAV DX just because it's 50,000 sqft and the attached warehouse is 55,000 sqft? So, I understand it, but I think it should be addressed by ASHRAE and rules should be made for maximum space allowed for the exception. But still allow for the baseline of the other spaces to be considered on their own if they have different occupancy, operating, or peak loads. I think exception A could be expanded beyond residential/non-residential or heating, to also include exception B or C so that a 20,000 sqft cutoff is established for CAV DX.
You could make the same argument about any "boundary" level established in the standard.
I agree that it should be addressed by ASHRAE so let us know if you hear anything.
Does the LEED online form want me to list each space room by room, or are a few overall general space types okay? The building I am working on has beauty salon, spa, fitness, retail, dining, and food prep areas. And a few office/corridor/equipment rooms, etc.
Space types are fine.
I have a doubt related to the service hot water system for the baseline building.
In appendix G, it's said that "the service hot-water system in the baseline building design shall use the same energy source as the corresponding system in the proposed design and shall conform with the following conditions..."
In a specific project, I have 2 service hot-water systems: a gas instantaneous water heater and a solar + eletric auxiliar system.
So, in this case, for the baseline building, should I model 2 baseline systems?
Yes you should.
We are modeling a building that is separated into three different spaces. These spaces have differing functions, schedules and systems. There is an office, manufacturing area, and warehouse storage.
These 3 spaces combine to over 200,000 square foot, which would make our baseline system a chilled water system. However, it would behoove the project if we could separate out the 3 differing spaces and build a baseline system for each space to compare to. This would put each 'space' in the baseline building under 200,000 square foot and thus allow us to compare our proposed building model to 3 separate systems conditioned by System 3 or 4.
Since each oif these spaces is a minimum of 40,000+ square foot, can we use exception A in G3.1.1? Therefore the baseline and proposed buildings would each have 3 separate systems? If not, could we at least use exception B making them single zone constant volume systems?
Any help would be appreciated greatly. Thanks in advance.
First you enter Table G3.1.1A based on the square footage of the predominant condition (largest sf). You then apply any of the exceptions under G3.1.1.
G3.1.1 exception A only applies for the examples cited unless you can provide some similar justification. You can apply the other exceptions if you can demonstrate that the requirements within them apply.
The listed exceptions I see only differentiate heating source and residential/non-residential.
We would be differentiating a storage warehouse (only heated) and manufacturing plant (running 24x7 with large machinery) from a standard 40+ hour office. Do you have any experience with this? I would think that it meets the spirit of the rule, even if not clearly defined.
We are hoping to use the baseline based off of the 100,000 sf office (with the 50,000 sf warehouse and manufacturing areas) rooftop units in lieu of a chiller plant.
Any suggestions on how to do so and whether or not it would be agreeable to the USGBC would be great.
Thanks in advance.
Exception B lists differences in thermal loads and schedules. Exception C is related to air flow issues.
Sounds like either one might apply to at least part of your situation. We do have considerable experience with this situation. The reason for the exceptions is to allow secondary systems for significantly difference space types within the same building.
Sounds like the office area is predominant so the baseline is a system 5 or 6. The warehouse and manufacturing area also come in at a system 5 or 6 but exception b or c would likely apply allowing a system 3 or 4 as the baseline.
Another option would be to apply a system 9 or 10 from 90.1-2010 to the heated only spaces.
Would like to take this opportunity to clarify the baseline HVAC system type selection from Table G3.1.1A.
A footnote from Table G3.1.1A, states "where attributes make a building eligible for more than one baseline system type, use the predominant condition to determine the system type for the entire building". I understand that nonpredominant condition applied to differential of residential/nonresidential or heating source. This mean the use of predominant condition to determine the system type for the entire building is allowed when nonpredominnant condition exists.
In this case, reference to ASHRAE 90.1 2007, IF nonpredominant condition does not exist (nonresidential building and same heating source for all three space), system 7 or system 8 shall be applied for entire building, IF nonpredominant condition does exist (ie. storage warehouse and manufacturing area), office area here is predominant condition, thus apply system 5 or 6 to entire building and apply exception in G3.1.1 for storage warehouse and manutacturing area if applicable.
I had been interpreting the use of exceptions under G3.1.1 like you are suggesting - "use of predominant condition to determine the system type for the entire building is allowed" even if you have spaces that qualify under one of the exceptions under G3.1.1. If you read G3.1.1 it basically says follow Table G3.1.1A except where any of the exceptions apply. So the exceptions must be applied where applicable is the correct interpretation in my opinion.
Exceptions b, c, and d to G3.1.1 can also trigger nonpredominant condition in addition to exception a. So it it not just residential vs non and heating fuel type, it it also schedule, thermal loads, air flows, etc. that triggers an exception.
My project is very similar to this one. Our predominant space is actually the manufacturing area (73,000 sqft). The office is 60,000 and the warehouse is 50,000 sqft. This would make the office and warehouse both system 3 baseline. Can you tell me if there is an official document I can refer to when submitting our project for review that backs up this interpretation of 90.1?
The Advanced Energy Modeling Guide for LEED contains a summary of this approach.
Sorry for a couple of elementary questions, but my searches haven't been successful.
1. Is 90.1 compliance required, or only the mandatory provisions?
2. I have three floors that are empty, but planned future use is known, which will be identical to the floors above them. This future use will be designed, built, and occupied fairly soon after occupancy (maybe a year or two). I think it best to model these floors as copies of the known future layout and systems. It's sort of a gray area to me, though. Will that be OK?
1. You must comply with the mandatory provisions. The remaining prescriptive provisions are all available for trade-off as long as you can meet the minimum savings requirement.
2. If it is designed and will be occupied that way then modeling that way makes sense.
Condition: I have a completely unconditioned garage located in the cellar. There is no heating. No cooling. Only an exhaust fan and an opening in the entry gate to the garage to provide unconditioned fresh air. This garage fan operates via VFDA variable frequency drive (VFD) is a device for for controlling the speed of a motor by controlling the frequency of the electrical power supplied to it. VFDs may be used to improve the efficiency of mechanical systems as well as comfort, because they use only as much power as needed, and can be adjusted continuously. as there are carbon monoxide monitoring controls that allow fan speed to modulate based on those levels. I am NOT modeling this as a system as I am not required to given the fact that there is no cooling or heating (unconditioned spaces have neither heating nor cooling systems). The exhaust CFM and the fan power remains the same (as shown in the design dwgs) in the baseline and proposed cases. The only difference is that fan operating schedule: baseline is 100% on during occupied hours and the proposed case fluctuates based on a similar type of people schedule throughout the day.
The LEED reviewer has indicated this as a DCV system (?!) and has noted that I should be treating my exhaust fan according to the baseline fan power calcs AND the ASHRAE minimum ventilation rates. The reviewer is treating my system as DCV even though the ASHRAE application of DCV applies to CO2Carbon dioxide sensors and modulating occupancy, not CO (related to toxins in the air; as a result of increased intermittent occupancy).
In my opinion, this should be treated as an exceptional calc following the method I described earlier because fans that ventilate only, ie garage exhaust fans, are NOT qualified as a fan system, meaning that the fan power remain equal in both modeling cases. Additionally, the rules for modeling DCV do not apply in this case, for the reasons listed above.
Please let me know your thoughts.
Same as the answer further on in the string.
Technically it is a DCV as I understand the term but demand here is cars, not people. Sounds like you are using people as a proxy for cars.
It is definitely an exceptional calculation. You can find good guidance regarding garage usage in one of the ASHRAE Handbooks (can't recall which one right now). You will need to make sure this is not a local requirement (if it is you can't claim savings) and provide a good justification for the schedule you are using.
The Baseline fan volume should not exceed the minimum required ASHRAE 62.1 parking ventilation rates of 0.75 cfm/square foot. The Baseline fan power should be the same as the Proposed (unless you are using premium efficiency motors then the Baseline fan power can be a bit higher based on standard motors). I agree that G22.214.171.124 does not apply to this ventilation only system.
I have 222 thermal zones. This is a standard size project. I am trying to increase the turn around time on my current simulation.
For the proposed design model:
I have modelled each of the 13 AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition)
2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. including the VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. air terminals to all zones. In the proposed design there exists zone equipment including radiators, floor heating, chilled ceiling, fancoils.
For each zone, I propose to sum the equipment capacities of all zone equipments to create a single ideal heating/cooling "machine" to be found in that zone. The rated electrical consumption of all motors for the fancoils will be sepperately summed and entered as a user which does not impact on zone thermal loads (process equipment). A PLE (0.5) for the fancoil fan power will be assumed and held constant for when the "machine" is on, and this will be devided by the rated electrical consumption of all motors for the fancoils.
The CW and HW energy used by this zone "machine" will be converted into kgPh HW or CW mass flow to account for pumping power based on a dT of 20degC which is assumed an average for the zone equipment (eg. for heating radiator --> 20, fancoil --> 40, heated floor --> 20, ect.) This means the mass flow demand to the Chilled and Hot Water Plants will be inaccurate, but the energy delivered will be 100% accurate. In inaccuracy will result purely from an inaccuracy in resulting pumping power. This is only for the zone equipment. The main AHU and VAVreheat if there is any is 100% accurate.
ASHRAE 90.1 does not really elaborate on the modelling of the zone equipment. The baseline does not have any.
Would this fall into a "exceptional calculation method"?
Would you invest a 6 month period just to model all the zone equipment in detail?
Use the ECMEnergy conservation measures are installations or modifications of equipment or systems intended to reduce energy use and costs. if claiming savings for a non-regulated component (i.e. elevators), if you need to violate a modeling protocol to show savings (i.e. vary a schedule) or if using a work around in the model because your software cannot model something directly (i.e. daylighting in HAP). This certainly sounds like some kind of work around to me.
Hard to say how you would model something like this as it is usually very software dependent. If a model takes 6 months then it would be one of the most complicated models I have seen and I for one could certainly not afford to spend that kind of time.
I usually model with eplus. This time I'm using TrnSys. These are both very powerful engines and can model, just about anything.
I guess my point is that one can model practically everything down to the pressure drop in the hydrolic system...but it takes too much time. If there where just a few zones with not so much variation in zone equipment, then I would do it.
This is a work around, due to practical modelling needs. So I guess that qualifies as you said to use a ECMEnergy conservation measures are installations or modifications of equipment or systems intended to reduce energy use and costs. for that part of the modelling. As far as practically possible we model the proposed system as designed.
EnergyPlus and TrnSys can model just about anything and take considerably more time to do so in my experience. Now I understand the 6 month comment.
You are really touching on the art of energy modeling. How can you simplify the model without compromising accuracy to a significant degree? In my experience there is a rather large grey area on this issue, not a thin line, and it varies on practically each model.
I was looking for older posts regarding thermal zoning, and this is the closest I found relative to my question.
Ashrae 90.1 2007 describes how you should model the thermal zones of your building, and it basically says you should define them as they are in the HVAC drawings, with some exceptions. I usually never model all physical zones, but rather group them together based on the orientation, type of activity and the HVAC unit that serves them. My questions is how far can we group zones in order to simplify the model?
In my case I am modeling a laboratory building and it has many internal zones which I want to group in only 4 groups, depending on the orientation. Otherwise the model will get too big and complicated.
I have seen studies where they compare simulation results of a building modeled exactly as it is and modeled with less zones and the results do not differ more than 1%. Of course it is very dependent on the type of project, but I think that thermal zone grouping is very helpful to minimize simulation time.
See Table G3.1-7 for guidance on modeling thermal zones as you describe.
Does anyone have experience with justifying that the lower full load efficiency of magnetic bearing chillers is ok due to their exceptionally high IPLV?
ASHRAE 90.1-2007 and ARI 550/590 1998 don't exempt or even take magnetic bearing chillers into account.
ASHRAE 90.1-2010 takes them into account and allows for compliance.
Can ASHRAE90.1-2010 be used as an errata for 90.1-2007 in this case?
I would use the guidance from 90.1-2010 to show compliance.
We are working with and energy modeling software that does not have U-values for a soil or vegetated roof. Is there an official list (database) like ASHRAE LEED uses? Right now they have 2 inches of fiberglass for the calculation, which we figure is not correct. Any help is appreciated. Sorry for my ignorance, I am fairly new at this.
John, LEED does not use an official reference for U-factors.
If anything, LEED would defer to accepted energy modeling software, ASHRAE standards, or ASHRAE Fundamentals.
I know eQUEST has soil in its constructions library. You could download a free copy.
I´m not sure if we have modeled the HVAC baseline system correctly.
We are in a 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. 2a (São Paulo - Brazil). And we are using in the project building a single mini split system 9.000 BTUA unit of energy consumed by or delivered to a building. A Btu is an acronym for British thermal unit and is defined as the amount of energy required to increase the temperature of 1 pound of water by 1 degree Fahrenheit, at normal atmospheric pressure. Energy consumption is expressed in Btu to allow for consumption comparisons among fuels that are measured in different units., with CFMs of 620m3/h.
According to Table G3.1.1A (ASHRAE 90.1), we have used System nº 2- PTHP for baseline moleding. We though that for this scenario, we would not need an Ecnomonizes High-Limit shut-off, but USGBC is asking us to model baseline with an 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. and a supply-air-to-room-air cooling temperature difference of 11ºC.
Not sure where to plot this 11ºC temperature difference, and how to demonstrate that this HVAC is meant for cooling. why a high-limit shut-off is needed?
We are really lost in this one. Can anyone help with this issue?
I am confused as well. 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. 2a never should have an 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. in the baseline.
Is your project residential? Systems 1 and 2 are for residential buildings only.
If your baseline is indeed a system 2 then you do not have an economizer in the baseline (see G126.96.36.199).
If your baseline is a system 3 to 8 instead of system 2 and you are in climate zone 2a you would still not have an economizer in the baseline (see Table G188.8.131.52A).
Hey Marcus, thank you for all your attention.
Our project is not residential, it´s a small building which will be used for employees as a breakroom.
in the project building we only have a small room (14 m2) which will have this mechanincal ventilation system.
So what we should do is to run the baseline model again, considering system 4 I believe, I have to check is rooftop 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. aplies.
Then, I´ll need to calculate our fan power again right? Using the formula:
CFMs * 0.00094 +A?
Sounds like system 4 and yes you would need to redo the baseline fan power calculations since the formulas are different for a system 4 than a system 2. See G184.108.40.206
Hi! There has been an addenda incorporated in the reference guide to SSc8. According to this Individual Lighting Power Allowances for Building Exteriors is now zone dependent. However, the addenda does not indicate that this should be used for EAp2 as well. Do you think the addenda should be used for EAp2 if SSc8 is not attempted?
Follow the 90.1 methodology for EAp2. Do not make any adjustment related to SSc8. The Proposed values should match between SSc8 and EAp2. The baseline can vary slightly between the two.
We're working in the energetic simulation for the credit EA p 2 in LEED NC 2009 in a Data Center building. To that end, we're developing a model based on Appendix G "Performance Rating Method" of ASHRAE 90.1 2007.
For the "Proposed Building Performance" the efficiency for electric equipment is real efficiency. But there's no indication in ASHRAE 90.1 2007 for the efficiency in electric equipment for 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." for data centers (we have troubles for UPS and computer servers).
In Energy Star we've found two documents indicating the efficiency required for UPS´s and computer servers. These documents are: computer servers (Energy Star Program Requirements for Computer Servers Draft 1 Version 2.0) and UPS´s (Energy Star Program Requirements Product Specifications for Uninterruptible Power Supplies (UPS's) Eligibility Criteria Draft 3 Version 1.0).
My question is: Can we use the efficiency for UPS´s and computer servers indicated in these documents for baseline simulation? If not, what is the efficiency for UPS´s and computer servers we should use in the baseline simulation for the data center?
Thanks a lot for your help
Some additional guidance for data centers is contained in the next version of LEED, v4. The most recent version should be posted here on October 2nd - http://www.usgbc.org/DisplayPage.aspx?CMSPageID=2360
In the meantime you could contact GBCI and ask for some guidance on the issue.
Thank you Marcus!
I'm afraid we've already contacted GBCI and they recomend to place a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide.
I was hoping to find someone certifying a Data Center who had this problem before to explain how they've solved.
How long ago did you contact GBCI? There is a draft spreadsheet for data centers that has been used by submitted projects. The spreadsheet basically establishes the baseline. I would contact GBCI and ask for it.
I have the same problem as described above. I would like to define Baseline for a server room in an office building. As the server room constitutes for 70% of energy in the whole building, I can see a big potential in optimizing this part of the project.
Is there any chance you could send a link to these spreadsheets?
Thank you in advance
I have not seen it posted yet. Contact GBCI and ask for it.
I was wondering how I can find the Lighting Power Densities for Residential Buildings in ASHRAE 90.1-2007.
The 2 tables (Building Area Method & Space-by-Space) do not include categories specific to residential flats. Maybe "restrooms" and "family dining areas", but I'm not sure those are the most accurate.
Can someone please advise on the Baseline maximum LPDs for flats? We basically have:
2) Living rooms
3) Dining rooms
Residential lighting (beyond hotels and dorms) is not included in 90.1. See Table G3.1-6 (Proposed) (d) which indicates that the LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. must be identical in both models.
Restrooms and dining are for commercial spaces.
If you wish to claim savings you will need to do an exceptional calculation. There is further guidance in the Advanced Energy Modeling Guide for LEED.
We also were questioned regarding the construction assemblies used. USGBC says it´s unclear if the construction assemblies in the Proposed model reflect the assemblies in actual design.
How should we demonstrate that the construction assemblies used are the same as modeled in the proposed model?
Aprreciate any help!
You could provide section drawings to show the assemblies that were built or provide a thorough description of all the layers, constructions and the nature of any continuous insulation.
Also keep in mind that the U-valueU-value describes how well a building element conducts heat. It measures the rate of heat transfer through a building element over a given area, under standardized conditions. The greater the U-value, the less efficient the building element is as an insulator. The inverse of (1 divided by) the U-value is the R-value. of an assembly must be calculated according the ASHRAE 90.1-2007 Appendix A. The tables in this appendix de-rate the insulation values to account for thermal bridging. You cannot determine the whole assembly U-value by doing a point calculation through the insulation. The entire assembly must be included to determine the overall U-value. It is always good practice to cite the specific table from appendix A you are using to determine the assembly U-value.
USGBC is saying that the fenestration assembly U-valueU-value describes how well a building element conducts heat. It measures the rate of heat transfer through a building element over a given area, under standardized conditions. The greater the U-value, the less efficient the building element is as an insulator. The inverse of (1 divided by) the U-value is the R-value. and SHGCSolar heat gain coefficient (SHGC): The fraction of solar gain admitted through a window, expressed as a number between 0 and 1. value must be modeled at 4.26 and 0.25, we are changing the fenestration characteristcs in order to get as close to those values as possible. We got U-Value of 4.25 is it acceptable? For SHGC value we got the 0.25.
The same issue is on the U-values for the exterior wall and roof construction, which should be modeled (at baseline) with assembly values of 0.273 and 0.705 respectively. We got 0.271 and 0.704. Do they accept those values? We are not getting the exat number in our modeling program.
Those values should be acceptable to the reviewer.
For the purpose of energy modelling of an industrial building, there are rooms which have process related humidity control (humidity control which is not intended for comfort). Can humidity control, in such cases, be considered as "process energy"?
Yes and modeled identically in both models.
Appendix G states the following:
"All conditioned spaces in the proposed design shall be simulated as being both heated and cooled even if no heating or cooling system is to be installed"
1) So if I am modelling a building in a cold climate area where only heating is required, do I still need to model cooling? I find it really strange!
2) What about areas with mechanical ventilation only (such as underground parking with no cooling / heating)? Do these have to be modelled as cooled & heated, or those do not classify as conditioned?
I appreciate if someone knows the "logic" behind this - just for my own interest!
If the ventilated space is using non-conditioned air, then it is not a conditioned space, right? So this means it does not need a heating and cooling system.
But each space that has heating or cooling IS conditioned and must also have heating AND cooling...
Regarding modeling cooling - yes Appendix G requires this and it is kinda strange. The rational I have heard is that any space can add cooling in the future even if it is not in the original design.
There is a common work around for this requirement - set the temperature in the space during the cooling season so high that the system never operates. This is allowed as the temperature setting is not dictated by 90.1 (just don't try and claim the thermal comfort credit!). The reviewers understand this work around and usually will not make you model cooling in these spaces as an academic exercise. We would just explain that we understand the work around and in our opinion it is not productive to spend the time to model cooling. As a reviewer I let this slide all the time.
I have a project that is an exisiting building renovation with an addition. I understand my energy model will be based on a combination of the new & existing. But what about the mandatory ASHRAE requirements (for lighting, HVAC, envelope, etc), will the existing building have to be updated in all these areas to meet the mandatory ASHRAE requirements in order to comply with the prerequisite?
Thanks in advance
No the whole building does not have to meet the requirements, only the addition and any systems which are replaced or modified in the existing.
I have the following issue:
For the Certification of a Restaurant, there is an inside area that corresponds to cold storage rooms. This area has an independent air conditioning system since the temperature must be quite low during all year. My question is if for the baseline design I have to model the HVAC system type according to Table G3.1 section 10, even if it is not a regularly occupied area. Or can I use the same type of HVAC as the proposed design?
Many thanks in advance
Sounds like the space conditioning is related to the stuff in the room rather than the intermittent occupancy of the people. This sounds like a process load which should be modeled identical to the proposed.
I have a doubt related to Appendix G, concerning the number and type of chillers and I think you may help me.
In item G.220.127.116.11, it is specified that the number and type of chiller for the baseline model are a function of building peak cooling load.
In item G.18.104.22.168, it is specified that the baseline's equipment efficiency shall be oversized by 15% (cooling) and by 25% (heating).
So, in order to define the number and type of chillers, may I use the oversized capacity or the non- oversized one?
This is a good question! What I have always done is to 1st set the oversizing factors, then perform a simulations with auto-sized equipment, then use the results to determine the number of chillers.
But actually the building cooling load is not affected by the sizing of the equipment!
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EAc1 relies directly on the EAp2 documentation, and the strategies to earn the prerequisite are often similar to earning points under the credit.
Limits on interior and exterior light use can help in reducing energy loads.
Daylighting reduces demand on installation and use of lighting fixtures resulting in energy use. To full realize the energy benefits, contorl electrical lighting with daylight sensors.
Commissioning of energy-efficient building systems helps realize he operational benefits of the design.
Onsite renewable energy contributes to prerequisite achievement if pursuing energy modeling under Option 1.
The computer model developed for EAp2 – Option 1 is used in the M&V plan.
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