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 22.214.171.124c, a manual control device would be sufficient to comply with mandatory provisions.
Submitting these forms is not common; however, it can be beneficial if you are applying for any exceptions.
Use the building area method.
Although there is no formal list of approved simulation tools, there are a few requirements per G2.2.1, including the ability of the program to provide hourly simulation for 8760 hours per year, and model ten or more thermal zones, which PHPP does not meet.
The automated Trace 700 report provides less information than is requested by the Section 1.4 tables spreadsheet. The Section 1.4 tables spreadsheet must be completed.
Assign HVAC systems as per Appendix-G and Section 6 but set thermostatic setpointsSetpoints are normal operating ranges for building systems and indoor environmental quality. When the building systems are outside of their normal operating range, action is taken by the building operator or automation system. out of range so that systems never turn on.
If it is only used for backup and not for regular use such as peak shaving—no.
SHGC is not a mandatory provision so it is available for trade-off and can be higher than the baseline.
You generally wouldn't need to upload any documentation, but particularly for a non-U.S. project, it may help to provide a short narrative about what they are based on.
Discuss your project’s energy performance objectives, along with how those are shaping design decisions, with the owner. Record energy targets in the Owners Project Requirements (OPR) for the commissioning credits EAp1 and EAc3.
You won’t earn this prerequisite by accident. The energy efficiency requirements here are typically much more stringent than local codes, so plan on giving it special attention with your team, including leadership from the owner.
Consider stating goals in terms of minimum efficiency levels and specific payback periods. For example: “Our goal is to exceed a 20% reduction from ASHRAE 90.1, with all efficiency measures having a payback period of 10 years or less.”
Develop a precedent for energy targets by conducting research on similar building types and using the EPA’s Target Finder program. (See Resources.)
For Option 1 only, you will need to comply with the mandatory requirements of ASHRAE 90.1-2007, to bring your project to the minimum level of performance. The ASHRAE 90.1-2007 User’s Manual is a great resource, with illustrated examples of solutions for meeting the requirements.
ASHRAE 90.1-2007 has some additional requirements compared with 2004. Read through the standard for a complete update. The following are some samples.
The prerequisite’s energy-reduction target of 10% is not common practice and is considered beyond code compliance.
Indirect sunlight delievered through clerestories like this helps reduce lighting loads as well as cooling loads. Photo – YRG Sustainability, Project – Cooper Union, New York A poorly designed envelope with a high-tech HVAC system is not, on the whole, efficient or cost-effective. Start with building orientation and passive design features first when looking for energy efficiency. Also look at envelope design, such as energy-efficient windows, walls and roof, before looking at HVAC and plug loads. HVAC may also be a good place to improve performance with more efficient equipment, but first reducing loads with smaller equipment can lead to even greater operational and upfront savings. A poorly designed envelope with a high-tech HVAC system is not, on the whole, efficient or cost-effective.
Don’t plan on using onsite renewable energy generation (see EAc2) to make your building energy-efficient. It is almost always more cost-effective to make an efficient building, and then to add renewables like photovoltaics as the “icing” on the cake.
Some rules of thumb to reduce energy use are:
Find the best credit compliance path based on your building type and energy-efficiency targets. Use the following considerations, noting that some projects are more suited to a prescriptive approach than others.
Option 1: Whole Building Energy Simulation requires estimating the energy use of the whole building over a calendar year, using methodology established by ASHRAE 90.1-2007, Appendix G. Option 1 establishes a computer model of the building’s architectural design and all mechanical, electrical, domestic hot water, plug load, and other energy-consuming systems and devices. The model incorporates the occupancy load and a schedule representing projected usage in order to predict energy use. This compliance path does not prescribe any technology or strategy, but requires a minimum reduction in total energy cost of 10% (5% for an existing building), compared to a baseline building with the same form and design but using systems compliant with ASHRAE 90.1-2007. You can earn additional LEED points through EAc1 for cost reductions of 12% and greater (8% for existing buildings).
Option 2: Prescriptive Compliance Path: ASHRAE Advanced Energy Design Guide refers to design guides published by ASHRAE for office, school, warehouse, and retail projects. These guides outline strategies to reduce energy use by 30% from ASHRAE 90.1-2001 levels, or an amount equivalent to a 10%–14% reduction from the ASHRAE 90.1-2007 standard. If you choose this compliance path, become familiar with the list of prescriptive requirements and commit to meeting them. (See the AEDG checklist in the Documentation Toolkit.)
Option 3: Prescriptive Compliance Path: Advanced Buildings Core Performance Guide is another, more basic prescriptive path. It’s a good option if your project is smaller than 100,000 ft2, cannot pursue Option 2 (because there is not an ASHRAE guide for the building type), is not a healthcare facility, lab, or warehouse—or you would rather not commit to the energy modeling required for Option 1. Your project can be of any other building type (such as office or retail). To meet the prerequisite, you must comply with all requirements within Sections 1 and 2 of the guide. If you choose this path, become familiar with the list of activities and requirements and commit to meeting them. (See Resources for a link to the Core Performance Guide and the Documentation Toolkit for the checklist of prescriptive items.)
EAc1: Optimize Energy Performance uses the same structure of Options 1–3, so it makes sense to think about the credit and the prerequisite together when making your choice. In EAc1, Option 1 offers the potential for far more points than Options 2 and 3, so if you see your project as a likely candidate for earning those points, Option 1 may be best.
Hotels, multifamily residential, and unconventional commercial buildings may not be eligible for either Option 2 or Option 3, because the prescriptive guidance of these paths was not intended for them. Complex projects, unconventional building types, off-grid projects, or those with high energy-reduction goals are better off pursuing Option 1, which provides the opportunity to explore more flexible and innovative efficiency strategies and to trade off high-energy uses for lower ones.
If your project combines new construction and existing building renovation then whatever portion contains more than 50% of the floor area would determine the energy thresholds.
Options 2 and 3 are suitable for small, conventional building types that may not have as much to gain from detailed energy modeling with Option 1.
Meeting the prescriptive requirements of Options 2 and 3 is not common practice and requires a high degree of attention to detail by your project team. (See the Documentation Toolkit for the Core Performance Guide Checklist.) These paths are more straightforward than Option 1, but don’t think of them as easy.
Options 2 and 3 require additional consultant time from architects and MEP engineers over typical design commitment, which means higher upfront costs.
Option 1 references the mandatory requirements of ASHRAE 90.1-2007, which are more stringent than earlier LEED rating systems that referred to ASHRAE 90.1-2004.
Option 1 energy simulation provides monthly and annual operating energy use and cost breakdowns. You can complete multiple iterations, refining energy-efficiency strategies each time. Payback periods can be quickly computed for efficiency strategies using their additional first costs. A building’s life is assumed to be 60 years. A payback period of five years is considered a very good choice, and 10 years is typically considered reasonable. Consult the OPR for your owners’ goals while selecting your efficiency strategies.
Option 1 energy simulation often requires hiring an energy modeling consultant, adding a cost (although this ranges, it is typically on the order of $0.10–$0.50/ft2 depending on the complexity). However, these fees produce high value in terms of design and decision-making assistance, and especially for complex or larger projects can be well worth the investment.
All compliance path options may require both the architectural and engineering teams to take some time in addition to project management to review the prescriptive checklists, fill out the LEED Online credit form, and develop the compliance document.
The architect, mechanical engineer, and lighting designer need to familiarize themselves and confirm compliance with the mandatory requirements of ASHRAE 90.1-2007, sections 5–9.
Use simple computer tools like SketchUp and Green Building Studio that are now available with energy analysis plug-ins to generate a first-order estimate of building energy use within a climate context and to identify a design direction. Note that you may need to refer to different software may not be the one used to develop complete the whole building energy simulations necessary for LEED certification.
Energy modeling can inform your project team from the start of design. Early on, review site climate data—such as temperature, humidity and wind, available from most energy software—as a team. Evaluate the site context and the microclimate, noting the effects of neighboring buildings, bodies of water, and vegetation. Estimate the distribution of energy across major end uses (such as space heating and cooling, lighting, plug loads, hot water, and any additional energy uses), targeting high-energy-use areas to focus on during design.
Use a preliminary energy use breakdown like this one to identify target areas for energy savings.Perform preliminary energy modeling in advance of the schematic design phase kick-off meeting or design charrette. The energy use breakdown can help identify targets for energy savings and point toward possible alternatives.
For existing buildings, the baseline energy model can reflect the pre-renovation features like rather than a minimally ASHRAE-compliant building. This will help you achieve additional savings in comparison with the baseline.
Projects generating renewable energy onsite should use Option 1 to best demonstrate EAp2 compliance and maximize points under EAc1. Other options are possible but won’t provide as much benefit. Like any other project, model the baseline case as a system compliant with ASHRAE 90.1-2007, using grid-connected electricity, and the design case is an “as-designed” system also using grid-connected electricity. You then plug in 100% onsite renewable energy in the final energy-cost comparison table, as required by the performance rating method (PRM) or the modeling protocol of ASHRRAE 90.1 2007, Appendix G. (Refer to the sample PRM tables in the Documentation Toolkit for taking account of onsite renewable energy.
LEED divides energy-using systems into two categories:
The energy model itself will not account for any change in plug loads from the baseline case, even if your project is making a conscious effort to purchase Energy Star or other efficient equipment. Any improvement made in plug loads must be documented separately, using the exceptional calculation methodology (ECM), as described in ASHRAE 90.1-2007. These calculations determine the design case energy cost compared to the baseline case. They are included in the performance rating method (PRM) table or directly in the baseline and design case model.
Besides energy modeling, you may need to use the exceptional calculation methodology (ECM) when any of the following situations occur:
Some energy-modeling software tools have a daylight-modeling capability. Using the same model for both energy and IEQc8.1: Daylight and Views—Daylight can greatly reduce the cost of your modeling efforts.
Provide a copy of the AEDG for office, retail, or warehouse, as applicable, to each team member as everyone, including the architect, mechanical and electrical engineers, lighting designer, and commissioning agents, are responsible for ensuring compliance. These are available to download free from the ASHRAE website. (See Resources.)
Find your climate zone before attempting to meet any detailed prescriptive requirements. Climate zones vary by county, so be sure to select the right one. (See the Documentation Toolkit for a list of climate zones by county.)
Develop a checklist of all requirements, and assign responsible team members to accomplish them. Hold a meeting to walk the team through the AEDG checklist for your project’s climate zone. Clarify specific design goals and prescriptive requirements in the OPR for EAp1: Fundamental Commissioning.
Early access to the AEDG by each team member avoids last-minute changes that can have cascading, and costly, effects across many building systems.
The AEDG prescriptive requirements include:
If your project team is not comfortable following these guidelines, consider switching to Option 1, which gives you more flexibility.
Although Option 2 is generally lower cost during the design phase than energy modeling, the compliance path is top heavy—it requires additional meeting time upfront for key design members.
Provide a copy of the New Buildings Institute Advanced Buildings: Core Performance Guide to each team member. The guide is available to download free from the NBI website. (See Resources.)
The guide provides practical design assistance that can be used throughout the design process.
Walk your team through the project checklist to clarify design goals and prescriptive requirements.
The guide provides an outline for approaching an energy-efficient design, in addition to a list of prescriptive measures. The first of its three sections emphasizes process and team interaction rather than specific building systems or features. Advise the owner to read through the guide in order to understand what is required of the architect and engineers.
Section 1 in the guide focuses on best practices that benefit the project during the pre-design and schematic design stages, such as analyzing alternative designs and writing the owner’s project requirements (OPR).
Section 2 of the Core Performance Guide describes architectural, lighting, and mechanical systems to be included. Section 3 is not required for EAp2 but includes additional opportunities for energy savings that can earn EAc1 points.
The guide mandates that your team develop a minimum of three different design concepts to select from for best energy use.
Though they can be a little daunting at first glance, a majority of the guide’s requirements overlap with other LEED credits, such as EAp1: Fundamental Commissioning, IEQp1: Minimum Indoor Air Quality Performance, and IEQc6.1: Controllability of Systems—Lighting Controls.
This compliance path is top-heavy due to upfront consultant time, but it provides adequate structure to ensure that your project is in compliance with the prerequisite requirements. For some projects it may be less expensive to pursue than Option 1.
The owner should now have finalized the OPR with the support of the architect, as part of the commissioning credits EAp1 and EAc3. The goals identified here will help your team identify energy-reduction and occupant-comfort strategies.
Consider a broad range of energy-efficiency strategies and tools, including passive solar, daylighting, cooling-load reduction, and natural ventilation to reduce heating and cooling loads.
Develop the basis of design (BOD) document in conjunction with your mechanical engineer and architect for EAp1: Fundamental Commissioning, noting key design parameters to help strategize design direction as outlined in the OPR.
The OPR and BOD serve the larger purpose of documenting the owner’s vision and your team’s ideas to meet those goals. The BOD is intended to be a work-in-progress and should be updated at all key milestones in your project. Writing the document gives you an opportunity to capture the owner’s goals, whether just to meet the prerequisite or to achieve points under EAc1.
Confirm that your chosen compliance path is the most appropriate for your project, and make any changes now. Following a review with the design team and owner, ensure that everyone is on board with contracting an energy modeler for Option 1 or meeting all the prescriptive requirements under Options 2 or 3.
Sometimes teams change from Option 1 to Options 2 or 3 very late in the design phase for various reasons including not realizing the cost of energy modeling. Making that change is risky, though: the prescriptive paths are all-or-nothing—you must comply with every item, without exception. Evaluate each requirement and consult with the contractor and estimator to ensure the inclusion of all activities within project management.
To avoid costly, last-minute decisions, develop a comprehensive, component-based cost model as a decision matrix for your project. The model will help establish additional cost requirements for each energy conservation measure. It will also illustrate cost reductions from decreased equipment size, construction rendered unnecessary by energy conservation measures, and reduced architectural provisions for space and equipment access. (See the Documentation Toolkit for an example.)
Use envelope design and passive strategies to reduce the heating and cooling loads prior to detailed design of HVAC systems. Passive strategies can reduce heating and cooling loads, giving the engineer more options, including smaller or innovative systems.
Load reduction requires coordinated efforts by all design members including the architect, lighting designer, interior designer, information-technology manager, and owner.
Involving facilities staff in the design process can further inform key design decisions, helping ensure successful operation and low maintenance costs.
Encourage your design team to brainstorm design innovations and energy-reduction strategies. This provides a communication link among team members so they can make informed decisions.
More energy-efficient HVAC equipment can cost more relative to conventional equipment. However, by reducing heating and cooling loads through good passive design, the mechanical engineer can often reduce the size and cost of the system. Reduced system size can save money through:
Review case studies of similar energy-efficient buildings in the same climate to provide helpful hints for selecting energy-efficiency measures. For example, a building in a heating-dominated climate can often benefit from natural ventilation and free cooling during shoulder seasons. (See Resources for leading industry journals showcasing success stories around the country and internationally.)
The relationship between first costs and operating costs can be complex. For example, more efficient windows will be more expensive, but could reduce the size and cost of mechanical equipment. A more efficient HVAC system may be more expensive, but will reduce operating costs. Play around with variables and different strategies to get the right fit for the building and the owner’s goals as stated in the OPR.
Review and confirm compliance with the mandatory requirements of all the relevant sections of ASHRAE 90.1-2007
Trust your project’s energy modeling task to a mechanical firm with a proven track record in using models as design tools, and experience with your building type.
Contract an energy modeling team for the project. These services may be provided by the mechanical engineering firm on the design team or by an outside consultant. Software used for detailed energy use analysis and submitted for final LEED certification must be accepted by the regulatory authority with jurisdiction, and must comply with paragraph G2.2 of ASHRAE Standard 90.1-2007. Refer to Resources for a list of Department of Energy approved energy-analysis software that may be used for LEED projects.
Design team members, including the architect and mechanical engineer at a minimum, need to work together to identify a percentage improvement goal for project energy use over the ASHRAE 90.1-2007-compliant baseline model. The percentage should be at least 10% to meet the prerequisite.
Plan on initiating energy modeling during the design process, and use it to inform your design—preferably executing several iterations of the design as you improve the modeled energy performance.
Ask the modeling consultant to develop an annual energy-use breakdown—in order to pick the “fattest” targets for energy reduction. A typical energy-use breakdown required for LEED submission and ASHRAE protocol includes:
Identify critical areas in which to reduce loads. For example, in a data center, the plug loads are the largest energy load. Small changes in lighting density might bring down the energy use but represent only a small fraction of annual energy use.
Don't forget that LEED (following ASHRAE) uses energy cost and not straight energy when it compares your design to a base case. That's important because you might choose to use a system that burns natural gas instead of electricity and come out with a lower cost, even though the on-site energy usage in kBtus or kWhs is higher. Generally you have to specify the same fuel in your design case and in the base case, however, so you can't simply switch fuels to show a cost savings
Explore and analyze design alternatives for energy use analyses to compare the cost-effectiveness of your design choices. For example, do you get better overall performance from a better window or from adding a PV panel? Will demand-control ventilation outperform increased ceiling insulation?
Simple, comparative energy analyses of conceptual design forms are useful ways to utilize an energy model at this stage. Sample scenarios include varying the area of east-facing windows and looking at 35% versus 55% glazing. Each scenario can be ranked by absolute energy use to make informed decisions during the design stage.
If your project is using BIM software, the model can be plugged into the energy analysis software to provide quick, real-time results and support better decisions.
Model development should be carried out following the PRM from ASHRAE 90.1-2007, Appendix G, and the LEED 2009 Design and Construction Reference Guide, Table in EAc1. In case of a conflict between ASHRAE and LEED guidelines, follow LEED.
Projects using district energy systems have special requirements. For EAp2, the proposed building must achieve the 10% energy savings without counting the effects of the district generation system. To earn points in EAc1 you can take advantage of the district system’s efficiency, but you have to run the energy model again to claim those benefits (see EAc1 for details).
While you could run the required energy model at the end of the design development phase, simply to demonstrate your prerequisite compliance, you don’t get the most value that way in terms of effort and expense. Instead, do it early in the design phase, and run several versions as you optimize your design. Running the model also gives you an opportunity to make improvements if your project finds itself below the required 10% savings threshold.
The baseline model is the designed building with mechanical systems specified in ASHRAE 90.1-2007, Appendix G, for the specific building type, with a window-to-wall ratio at a maximum of 40%, and minimally code-compliant specifications for the envelope, lighting, and mechanical components. It can be developed as soon as preliminary drawings are completed. The baseline is compared to the design case to provide a percentage of reduction in annual energy use. To avoid any bias from orientation, you need to run the baseline model in each of the four primary directions, and the average serves as your final baseline figure.
The design-case is modeled using the schematic design, orientation, and proposed window-to-wall ratio—¬the model will return design-case annual energy costs. Earn points by demonstrating percentage reductions in annual energy costs from the design to the baseline case. EAp2 is achieved if the design case is 10% lower than the baseline in new construction (or 5% less in existing building renovations).
Provide as much project and design detail to the modeler as possible. A checklist is typically developed by the energy modeler, listing all the construction details of the walls, roof, slabs, windows, mechanical systems, equipment efficiencies, occupancy load, and schedule of operations. Any additional relevant information or design changes should be brought to the modeler’s attention as soon as possible. The more realistic the energy model is, the more accurate the energy use figure, leading to better help with your design.
Invite energy modelers to project meetings. An experienced modeler can often assist in decision-making during design meetings, even without running complete models each time.
All known plug loads must be included in the model. The baseline and design-case models assume identical plug loads. If your project is deliberately attempting to reduce plug loads, demonstrate this by following the exceptional calculation method (ECM), as described in ASHRAE 90.1-2007, G2.5. Incorporate these results in the model to determine energy savings.
For items outside the owner’s control—like lighting layout, fans and pumps—the parameters for the design and baseline models must be identical.
It can take anywhere from a few days to a few weeks to generate meaningful energy modeling results. Schedule the due dates for modeling results so that they can inform your design process.
Review the rate structure from your electrical utility. The format can inform your team of the measures likely to be most effective in reducing energy costs, especially as they vary over season, peak load, and additional charges beyond minimum energy use.
Performing a cost-benefit analysis in conjunction with energy modeling can determine payback times for all the energy strategies, helping the iterative design process.
Using energy modeling only to check compliance after the design stage wastes much of the value of the service, and thus your investment.
The architect and mechanical engineer should carefully read the applicable ASHRAE Advanced Energy Design Guide for office, warehouse, or retail projects, as applicable.
Keep the owner abreast of the design decisions dictated by the standard. Fill in the team-developed checklist, within the climate zone table’s prescribed requirements, with appropriate envelope improvements, system efficiencies, and a configuration that meets the standard requirements.
As a prescriptive path, this option relies heavily on following the requirement checklist, which is used throughout the design process to track progress. To assist design development, provide all critical team members—not limited to the architect, mechanical and electrical engineers, and lighting designer—with a checklist highlighting their appointed tasks.
The architect, mechanical engineer, and lighting designer need to discuss each requirement and its design ramifications. Hold these meetings every six to eight weeks to discuss progress and make sure all requirements are being met.
Confirm that your project team is comfortable with following all the prescribed requirements. If not, switch to Option 1: Whole Building Energy Simulation.
The LEED Online credit form does not specify how to document each prescriptive requirement because they are so different for each project; it only requires a signed confirmation by the MEP for meeting AEDG requirements. You still have to provide documentation. Submit your checklist of requirements, and supporting information for each item, through LEED Online to make your case. If your project fails to meet even one requirement, it will fail to earn the prerequisite, thus jeopardizing LEED certification.
Although energy modeling consultant costs are avoided by this option, additional staff time will be required to document and track compliance status, as compared with conventional projects.
Energy efficiency measures prescribed by the guide can be perceived as additional costs in comparison with conventional projects. However, they are easy to implement and are cost-effective pn the whole.
Become familiar with the Core Performance Guide early in the design phase to know the multiple requirements and all requisite documents.
Note that the guide demands additional time, attention, and integrated process from the design team as compared to conventional projects. It’s not just a list of prescriptive requirements, but a prescribed process for achieving energy efficiency goals. LEED Online documentation requires proof of all steps outlined in Sections 1 and 2, including three conceptual design options and meeting minutes. The project manager, architect, and mechanical engineer should read the complete Core Performance Guide carefully to know beforehand the prescriptive requirements in Sections 1 and 2.
The project manager must take responsibility for ensuring that the requirement checklist is on track.
For Section 3, the design team needs to identify three or more of the listed strategies as possible targets for the project.
Create a checklist of requirements and assign a responsible party to each item.
The Core Performance Guide requires an integrated design contributed by the architect, mechanical and electrical engineers, and lighting designer. The project manager must take responsibility for shepherding and documenting the collaborative process to demonstrate compliance.
A long documentation list can be overwhelming for your team, so create a detailed checklist with tasks delegated to individual team members, allowing each member to focus on assigned tasks. The checklist can function as a status tracking document and, finally, the deliverable for LEED Online.
The architect and engineer, and other project team members, continue to develop a high-performance building envelope with efficient mechanical and lighting systems.
Constant communication and feedback among project team members, owner, and if possible, operational staff, during design development can minimize construction as well as operational costs and keep your project on schedule.
If you change or go through value-engineering on any specifications, such as the solar-heat gain coefficient of glazing, for example, be aware of impacts on mechanical system sizing. Making changes like this might not pay off as much as it first appears.
Consider using building information modeling (BIM) tools to keep design decisions up to date and well documented for all team members.
Schedule delays can be avoided if all team members share their ideas and update documents during the design development process.
The modeler completes the energy analysis of the selected design and system and offers alternative scenarios for discussion. The modeler presents the energy cost reduction results to the team, identifying the LEED threshold achieved.
It’s helpful for the energy modeling report to include a simple payback analysis to assist the owner in making an informed decision on the operational savings of recommended features.
The architect and HVAC engineer should agree on the design, working with the cost estimator and owner.
Demonstrating reductions in non-regulated loads requires a rigorous definition of the baseline case. The loads must be totally equivalent, in terms of functionality, to the proposed design case. For example, reducing the number of computers in the building does not qualify as a legitimate reduction in non-regulated loads. However, the substitution of laptops for desktop computers, and utilization of flat-screen displays instead of CRTs for the same number of computers, may qualify as a reduction.
Residential and hospitality projects that use low-flow showers, lavatories, and kitchen sinks (contributing to WEp1) benefit from lower energy use due to reduced overall demand for hot water. However, for energy-savings calculations, these are considered process loads that must be modeled as identical in baseline and design cases, or you have the choice of demonstrating the savings with ECM for process loads.
Perform daylight calculations in conjunction with energy modeling to balance the potentially competing goals of more daylight versus higher solar-heat gain resulting in high cooling loads.
If your project is pursuing renewable energy, the energy generated is accounted for by using the PRM. These results provide information about whether the energy is contributing to EAc2: Onsite Renewable Energy.
A cost-benefit analysis can help the owner understand the return on investment of big-ticket, energy-conserving equipment that lowers operating energy bills with a quick payback.
Complete at least half of the energy modeling effort by the end of the design development stage. Help the design team to finalize strategy through intensive, early efforts in energy modeling. Once the team has a design direction, the modeler can develop a second model during the construction documents phase for final confirmation.
If pursuing ECM for non-regulated loads, calculate energy saving for each measure separately if you are, for example, installing an energy-efficient elevator instead of a typical one so that the reduction would contribute to total building energy savings. Calculate the anticipated energy use of the typical elevator in kBTUs or kWh. Using the same occupancy load, calculate the energy use of the efficient elevator. Incorporate the savings into design case energy use within the PRM. Refer to the ECM strategy for detailed calculation guidelines.
Ensure that all prescriptive requirements are incorporated into the design by the end of the design development stage.
Revisit the Advanced Energy Design Guides (AEDG) checklist to ensure that the design meets the prescriptive requirements.
The mechanical engineer, lighting consultant, and architect revisit the checklist for an update on the requirements and how they are being integrated into the design. All prescriptive requirements should be specifically incorporated into the design by the end of the design development phase.
The mechanical engineer and architect track the status of each requirement.
While the LEED Online credit form does not require detailed documentation for each Core Performance Guide requirement, it is important that each item be documented as required and reviewed by the rest of the team to confirm compliance, especially as further documentation may be requested by during review. Your design team should work with the owner to identify cost-effective strategies from Section 3 that can be pursued for the project.
Construction documents clearly detail the architectural and mechanical systems that address energy-efficiency strategies.
Confirm that specifications and the bid package integrate all equipment and activities associated with the project.
If the project goes through value engineering, refer to the OPR and BOD to ensure that no key comfort, health, productivity, daylight, or life-cycle cost concerns are sacrificed.
During the budget estimating phase, the project team may decide to remove some energy-saving strategies that have been identified as high-cost items during the value-engineering process. However, it is very important to help the project team understand that these so-called add-ons are actually integral to the building’s market value and the owner’s goals.
Removing an atrium, for example, due to high cost may provide additional saleable floor area, but may also reduce daylight penetration while increasing the lighting and conditioning loads.
Although this prerequisite is a design-phase submittal, it may make sense to submit it, along with EAc1, after construction. Your project could undergo changes during construction that might compel a new run of the energy model to obtain the latest energy-saving information. Waiting until the completion of construction ensures that the actual designed project is reflected in your energy model.
Create a final energy model based completely on construction document drawings—to confirm actual energy savings as compared to ASHRAE 90.1-2007 requirements. An energy model based on the construction documents phase will provide realistic energy-cost savings and corresponding LEED points likely to be earned.
Make sure the results fit the LEED Online credit form requirements. For example, the unmet load hours have to be less than 300 and process loads will raise a red flag if they’re not approximately 25%. If any of the results are off mark, take time to redo the model. Time spent in design saves more later on in the LEED review process.
Finalize all design decisions and confirm that you’ve met all of the prescriptive requirements. Your team must document the checklist with relevant project drawings, including wall sections, specifications, and the MEP drawing layout.
Value engineering and other factors can result in design changes that eliminate certain energy features relevant to the prerequisite. As this compliance path is prescriptive, your project cannot afford to drop even one prescribed item.
Value engineering and other factors can result in design changes that eliminate certain energy features relevant to the credit. As this compliance path is prescriptive, your project cannot afford to drop even one listed item. Although perceived as high-cost, prescriptive requirements lower energy costs during operation and provide a simple payback structure.
The architect and mechanical engineer review the shop drawings to confirm the installation of the selected systems.
The commissioning agent and the contractor conduct functional testing of all mechanical equipment in accordance with EAp1: Fundamental Commissioning and EAc3: Enhanced Commissioning.
Find your Energy Star rating with EPA’s Target Finder tool if your building type is in the database. Input your project location, size, and number of occupants, computers, and kitchen appliances. The target may be a percentage energy-use reduction compared to a code-compliant building, or “anticipated energy use” data from energy model results. Add information about your fuel use and rate, then click to “View Results.” Your Target Finder score should be documented at LEED Online.
Plan for frequent site visits by the mechanical designer and architect during construction and installation to make sure construction meets the design intent and specifications.
Emphasize team interaction and construction involvement when defining the project scope with key design team members. Contractor and designer meetings can help ensure correct construction practices and avoid high change-order costs for the owner.
Subcontractors may attempt to add a premium during the bidding process for any unusual or unknown materials or practices, so inform your construction bidders of any atypical design systems at the pre-bid meeting.
The energy modeler ensures that any final design changes have been incorporated into the updated model.
Upon finalizing of the design, the responsible party or energy modeler completes the LEED Online submittal with building design inputs and a PRM result energy summary.
Although EAp2 is a design phase submittals, it may make sense to submit it (along with EAc1) after construction. Your project could undergo changes during construction that might require a new run of the energy model. Waiting until the completion of construction ensures that your actual designed project is reflected. On the other hand, it gives you less opportunity to respond to questions that might come up during a LEED review.
Include supporting documents like equipment cut sheets, specifications and equipment schedules to demonstrate all energy efficiency measures claimed in the building.
It common for the LEED reviewers to make requests for more information. Go along with the process—it doesn’t mean that you’ve lost the credit. Provide as much information for LEED Online submittal as requested and possible.
The design team completes the LEED Online documentation, signing off on compliance with the applicable AEDG, and writing the narrative report on the design approach and key highlights.
During LEED submission, the project team needs to make an extra effort to support the prerequisite with the completed checklist and the required documents. Although the LEED rating system does not list detailed documentation, it is best practice to send in supporting documents for the prescriptive requirements from the AEDG. The supporting documents should include relevant narratives, wall sections, mechanical drawings, and calculations.
Although the LEED Online sign-off does not include a checklist of AEDG requirements, it assumes that the team member is confirming compliance with all detailed requirements of the guide.
The design team completes the LEED Online credit form, signing off on compliance with the Core Performance Guide, and writing the narrative report on the design approach and key highlights.
During LEED submission, your project team needs to make an extra effort to support the prerequisite with the completed checklist and the required documents. Although not every requirement may be mentioned in the LEED documentation, the supporting documents need to cover all requirements with narratives, wall sections, mechanical drawings, and calculations.
Many of this option’s compliance documents are common to other LEED credits or design documents, thus reducing duplicated efforts.
Develop an operations manual with input from the design team in collaboration with facility management and commissioning agent if pursuing EAc3: Enhanced Commissioning.
The benefit of designing for energy efficiency is realized only during operations and maintenance. Record energy use to confirm that your project is saving energy as anticipated. If you are not pursuing EAc5: Measurement and Verification, you can implement tracking procedures such as reviewing monthly energy bills or on-the-spot metering.
Some energy efficiency features may require special training for operations and maintenance personnel. For example, cogeneration and building automation systems require commissioning and operator training. Consider employing a trained professional to aid in creating operation manuals for specialty items.
Energy-efficiency measures with a higher first cost often provide large savings in energy use and operational energy bills. These credit requirements are directly tied to the benefits of efficient, low-cost operations.
Excerpted from LEED 2009 for New Construction and Major Renovations
To establish the minimum level of energy efficiency for the proposed building and systems to reduce environmental and economic impacts associated with excessive energy use.
Demonstrate a 10% improvement in the proposed building performance rating for new buildings, or a 5% improvement in the proposed building performance rating for major renovations to existing buildings, compared with the baseline building performanceBaseline building performance is the annual energy cost for a building design, used as a baseline for comparison with above-standard design. rating.
Calculate the baseline building performance rating according to the building performance rating method in Appendix G of ANSI/ASHRAE/IESNA Standard 90.1-2007 (with errata but without addenda1) using a computer simulation model for the whole building project. Projects outside the U.S. may use a USGBC approved equivalent standard2.
Appendix G of Standard 90.1-2007 requires that the energy analysis done for the building performance rating method include all energy costs associated with the building project. To achieve points using this credit, the proposed design must meet the following criteria:
For the purpose of this analysis, process energy is considered to include, but is not limited to, office and general miscellaneous equipment, computers, elevators and escalators,kitchen cooking and refrigeration, laundry washing and drying, lighting exempt from the lighting power allowance (e.g., lighting integral to medical equipment) and other (e.g., waterfall pumps).
Regulated (non-process) energy includes lighting (for the interior, parking garage, surface parking, façade, or building grounds, etc. except as noted above), heating, ventilation and air conditioning (HVAC) (for space heating, space cooling, fans, pumps, toilet exhaust, parking garage ventilation, kitchen hood exhaust, etc.), and service water heating for domestic or space heating purposes.
Process loads must be identical for both the baseline building performance rating and the proposed building performance rating. However, project teams may follow the exceptional calculation method (ANSI/ASHRAE/IESNA Standard 90.1-2007 G2.5) or USGBC approved equivalent to document measures that reduce process loads. Documentation of process load energy savings must include a list of the assumptions made for both the base and the proposed design, and theoretical or empirical information supporting these assumptions.
Projects in California may use Title 24-2005, Part 6 in place of ANSI/ASHRAE/IESNA Standard 90.1-2007 for Option 1.
Comply with the prescriptive measures of the ASHRAE Advanced Energy Design Guide appropriate to the project scope, outlined below. Project teams must comply with all applicable criteria as established in the Advanced Energy Design Guide for the climate zoneOne of five climatically distinct areas, defined by long-term weather conditions which affect the heating and cooling loads in buildings. The zones were determined according to the 45-year average (1931-1975) of the annual heating and cooling degree-days (base 65 degrees Fahrenheit). An individual building was assigned to a climate zone according to the 45-year average annual degree-days for its National Oceanic and Atmospheric Administration (NOAA) Division. in which the building is located. Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone.
The building must meet the following requirements:
Comply with the prescriptive measures identified in the Advanced Buildings™ Core Performance™ Guide developed by the New Buildings Institute. The building must meet the following requirements:
Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone.
1Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.
2 Projects outside the U.S. may use an alternative standard to ANSI/ASHRAE/IESNA Standard 90.1-2007 if it is approved by USGBC as an equivalent standard using the process identified in the LEED 2009 Green Building Design and Construction Global ACP Reference Guide Supplement.
Design the building envelope and systems to meet baseline requirements. Use a computer simulation model to assess the energy performance and identify the most cost-effective energy efficiency measures. Quantify energy performance compared with a baseline building.
If local code has demonstrated quantitative and textual equivalence following, at a minimum, the U.S. Department of Energy (DOE) standard process for commercial energy code determination, then the results of that analysis may be used to correlate local code performance with ANSI/ASHRAE/IESNA Standard 90.1-2007. Details on the DOE process for commercial energy code determination can be found at http://www.energycodes.gov/implement/ determinations_com.stm.
1 Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.
2 Projects outside the U.S. may use an alternative standard to ANSI/ASHRAE/IESNA Standard 90.1‐2007 if it is approved by USGBC as an equivalent standard using the process located at www.usgbc.org/leedisglobal
This database shows state-by-state incentives for energy efficiency, renewable energy, and other green building measures. Included in this database are incentives on demand control ventilation, ERVs, and HRVs.
Useful web resource with information on local/regional incentives for energy-efficiency programs.
ACEEE is a nonprofit organization dedicated to advancing energy efficiency through technical and policy assessments; advising policymakers and program managers; collaborating with businesses, public interest groups, and other organizations; and providing education and outreach through conferences, workshops, and publications.
The New Buildings Institute is a nonprofit, public-benefits corporation dedicated to making buildings better for people and the environment. Its mission is to promote energy efficiency in buildings through technology research, guidelines, and codes.
The Building Energy Codes program provides comprehensive resources for states and code users, including news, compliance software, code comparisons, and the Status of State Energy Codes database. The database includes state energy contacts, code status, code history, DOE grants awarded, and construction data. The program is also updating the COMcheck-EZ compliance tool to include ANSI/ASHRAE/IESNA 90.1–2007. This compliance tool includes the prescriptive path and trade-off compliance methods. The software generates appropriate compliance forms as well.
Research center at RPI provides access to a wide range of daylighting resources, case studies, design tools, reports, publications and more.
International association of energy modelers with various national and local chapters.
Non-profit organization aiming at design community to increase collaboration for designing energy efficient buildings.
The Low Impact Hydropower Institute is a non-profit organization and certification body that establishes criteria against which to judge the environmental impacts of hydropower projects in the United States.
The Building Technologies Program (BTP) provides resources for commercial and residential building components, energy modeling tools, building energy codes, and appliance standards including the Buildings Energy Data Book, High Performance Buildings Database and Software Tools Directory.
This website discusses the step-by-step process for energy modeling.
This online resource, supported by Natural Resources Canada, presents energy-efficient technologies, strategies for commercial buildings, and pertinent case studies.
This website is a comprehensive resource for U.S. Department of Energy information on energy efficiency and renewable energy and provides access to energy links and downloadable documents.
Information on cogenerationThe simultaneous production of electric and thermal energy in on-site, distributed energy systems; typically, waste heat from the electricity generation process is recovered and used to heat, cool, or dehumidify building space. Neither generation of electricity without use of the byproduct heat, nor waste-heat recovery from processes other than electricity generation is included in the definition of cogeneration., also called combined heat and power, is available from EPA through the CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. Partnership. The CHP Partnership is a voluntary program seeking to reduce the environmental impact of power generation by promoting the use of CHP. The Partnership works closely with energy users, the CHP industry, state and local governments, and other clean energy stakeholders to facilitate the development of new projects and to promote their environmental and economic benefits.
Free download of AHSRAE energy savings guide, use for Option 2.
Research warehouse for strategies and case studies of energy efficiency in buildings.
An online window selection tool with performance characteristics.
This website lays out design process for developing an energy efficient building.
This website discusses ways to improve design for lower energy demand as they relate to the AIA 2030 challenge.
This website includes discussion of design issues, materials and assemblies, window design decisions and case studies.
This site lists multiple web-based and downloadable tools that can be used for energy analyses.
This database is maintainted by the California Energy Commission and lists resources related to energy use and efficiency.
Energy design tools are available to be used for free online or available to download.
This website lists performance characteristics for various envelope materials.
This is an online forum of discussion for energy efficiency, computer model software users.
Target Finder is a goal-setting tool that informs your design team about their project’s energy performance as compared to a national database of projects compiled by the EPA.
This directory provides information on 406 building software tools for evaluating energy efficiency, renewable energy, and sustainability in buildings.
Weather data for more than 2100 locations are available in EnergyPlus weather format.
Weather data for U.S. and Non-U.S. locations in BIN format.
A web-based, free content project by IBPSA-USA to develop an online compendium of the domain of Building Energy Modeling (BEM). The intention is to delineate a cohesive body of knowledge for building energy modeling.
A guide for achieving energy efficiency in new commercial buildings, referenced in the LEED energy credits.
This manual is a strategic guide for planning and implementing energy-saving building upgrades. It provides general methods for reviewing and adjusting system control settings, plus procedures for testing and correcting calibration and operation of system components such as sensors, actuators, and controlled devices.
This document is USGBC’s second (v2.0) major release of guidance for district or campus thermal energy in LEED, and is a unified set of guidance comprising the following an update to the original Version 1.0 guidance released May 2008 for LEED v2.x and the initial release of formal guidance for LEED v2009.
This manual offers guidance to building energy modelers, ensuring technically rigorous and credible assessment of energy performance of commercial and multifamily residential buildings. It provides a streamlined process that can be used with various existing modeling software and systems, across a range of programs.
Chapter 19 is titled, “Energy Estimating and Modeling Methods”. The chapter discusses methods for estimating energy use for two purposes: modeling for building and HVAC system design and associated design optimization (forward modeling), and modeling energy use of existing buildings for establishing baselines and calculating retrofit savings (data-driven modeling).
Required reference document for DES systems in LEED energy credits.
ASHRAE writes standards for the purpose of establishing consensus for: 1) methods of test for use in commerce and 2) performance criteria for use as facilitators with which to guide the industry.
Energy statistics from the U.S. government.
This guide includes instructional graphics and superior lighting design solutions for varying types of buildings and spaces, from private offices to big box retail stores.
This website offers information on energy efficiency in buildings, highlighting success stories, breakthrough technology, and policy updates.
Bimonthly publication on case studies and new technologies for energy efficiency in commercial buildings.
AIA publication highlighting local and state green building incentives.
2008 guidelines and performance goals from the National Science and Technology Council.
Information about energy-efficient building practices available in EDR's Design Briefs, Design Guidelines, Case Studies, and Technology Overviews.
DOE tools for whole building analyses, including energy simulation, load calculation, renewable energy, retrofit analysis and green buildings tools.
This is a computer program that predicts the one-dimensional transfer of heat and moisture.
DesignBuilder is a Graphical User Interface to EnergyPlus. DesignBuilder is a complete 3-D graphical design modeling and energy use simulation program providing information on building energy consumption, CO2Carbon dioxide emissions, occupant comfort, daylighting effects, ASHRAE 90.1 and LEED compliance, and more.
IES VE Pro is an integrated computing environment encompassing a wide range of tasks in building design including model building, energy/carbon, solar, light, HVAC, climate, airflow, value/cost and egress.
Use this checklist of prescriptive requirements (with sample filled out) to have an at-a-glance picture of AEDG requirements for Option 2, and how your project is meeting them.
This spreadsheet lists all the requirements for meeting EAp2 – Option 3 and and EAc1 – Option 3. You can review the requirements, assign responsible parties and track status of each requirement through design and construction.
Sometimes the energy simulation software being used to demonstrate compliance with Option 1 doesn't allow you to simulate key aspects of the design. In this situation you'll need to write a short sample narrative, as in these examples, describing the situation and how it was handled.
In your supporting documentation, include spec sheets of equipment described in the Option 1 energy model or Options 2–3 prescriptive paths.
This is a sample building energy performance and cost summary using the Performance Rating Method (PRM). Electricity and natural gas use should be broken down by end uses including space heating, space cooling, lights, task lights, ventilation fans, pumps, and domestic hot water, at the least.
Option 1 calculates savings in annual energy cost, but utility prices may vary over the course of a year. This sample demonstrates how to document varying electricity tariffs.
This graph, for an office building design, shows how five overall strategies were implemented to realize energy savings of 30% below an ASHRAE baseline. (From modeling conducted by Synergy Engineering, PLLC.)
The climate zones shown on this Department of Energy map are relevant to all options for this credit.
This spreadsheet, provided here by 7group, can be used to calculate the fan volume and fan power for Appendix G models submitted for EAp2/EAc1. Tabs are included to cover both ASHRAE 90.1-2004 and 90.1-2007 Appendix G methodologies.
The following links take you to the public, informational versions of the dynamic LEED Online forms for each NC-2009 EA credit. You'll need to fill out the live versions of these forms on LEED Online for each credit you hope to earn.
Version 4 forms (newest):
Version 3 forms:
These links are posted by LEEDuser with USGBC's permission. USGBC has certain usage restrictsions for these forms; for more information, visit LEED Online and click "Sample Forms Download."
Documentation for this credit can be part of a Design Phase submittal.
we are working on a residential project. The heating source of the project would be electric, so the baseline system should be System 2, Packaged terminal 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..
On the other hand one of the notes of table G3.1.1A states 'For all-electric buildings, the heating shall be electric resistance'.
Does this note apply to residential projects too? Can we model the heating as electrical resistance?
We checked if more detail is provided in the User's Manual, but this point is still not clear for us.
Do you have any experience on modeling residential baseline system as electrical resistance?
Thank you in advance!
Your initial assumption is correct. An all electric building would be compared to a System 2 (PTHP) baseline. The "electric resistance" note you reference is more clearly spelled out in 90.1-2010 in reference to laboratory buildings. Admittedly, the way the note is formatted is more confusing in 90.1-2007.
There is an issue on applying F factor about which I'd appreciate some assistance.
The F factor in general refers to the floor slab edge insulation. Its value depends also on how the rest of the slab is further insulated or not at all (Table A6.3).
In case of unheated slab, there is a compliance value for F factor to be entered in Baseline listed in tables 5.5. For the proposed case however this F factor usually is different because almost always the designers are applying some more insulation below the floor slab.
The questions are:
1. Is the F factor the only heat transfer coefficient to be applied in the floor slab?
2. Should F factor be applied also to the interior spaces, not only the exterior spaces?
3. Should the Proposed F factor value be applied the same also for the Baseline?
4. If the floor slab has different insulation thicknesses for different distance from the exterior, should the area averaged method be applied for determining the Assembly F factor?
1) 90.1 regulates F-Factor only for "Slab-on-grade" which has a very narrow definition...check it out. Otherwise, identical to proposed.
2) F-Factor applies to the entire slab under the building and is aspect ratio, perimeter dependant...which means you need to calculate it (read it off the table) for each new building for the baseline case and the proposed case is deturmined from Table A6.3 (interpolation is allowed).
3) Both proposed and baseline use F-Factor for slab-on-grade, but are not the same. Your software should know what to do with input F-factors.
4) For most element types 2D calc methods are allowed as alternitives. F-factor is the exception. You have to deturmine the F-Factor from the table A6.3.
If my slab-on-grade does not appear in table A6.3 (including interpolation), then I consider it not regulated by standard 90.1. Then I have to model the slab identically in both models. And then I try to do it as accurately as possible.
However, when it does appear in the table, it is usually in the Fully insulated section.
Thanks for the reply.
Something however still remains unclear.
The Slab on grade heat losses are function of F factor and perimeter of the spaces exposed to the ground. What I've been asking is how to proceed with interior spaces, which do not have such perimeter. Should they have heat losses to the ground or not and if yes (logically) how this F factor could be be applied and if it can't be applied, then should an U value for this surfaces be used. This issue is somehow not quite clear.
An answer to this question would be highly appreciated.
Logically, you are absolutely correct. In fact F-Factor is an ancient concept. I spoke to Joe Huang (whitebox technologies) who was partily responsible for creating the F-factors back in the day. He is still a bit flabbergasted that we are still using F-factors. Modern modelling tools can deal with slabs properly and the whole F-factor rating needs to be updated, if it hasn't been already.
Sadly, we are bound to use the standard "as is", which in this point in time means applying it to the whole slab (including sections which are more interior than others).
However, all that being said, generally the error in heatloss via the slab is only a very small fraction considering a) the total building energy use and b) the inherrent errors in the model due to other factors which I won't get into here.
This is my interpretation and opinion...anyone can contribute to the conversation, I'm all ears.
On our project we are getting supplied from local contractors materials like sandstone, granite, reused teak wood, and limestone. These materials are going into the floor and ceilings in various places in conditioned spaces. They come with no products sheets from the suppliers and the manufacturers have no U-values for them. I do not see stone mentioned in the Appendix tables for ASHRAE 90.1-2007, unless I am missing it. How would these be modeled in a program like Trace Trane? Also I am getting a request for the u-value of paint for the wall. Is that used in the energy model and how would one determine what that is? Thanks for your help!
You have to use the values of assemblies as per App. A. Failing that App. A allows you to calculate the values as per HOF or with a 2D/3D FEM software such as Therm so that the thermal bridging is taken into account. See App. A for details.
One of the ASHRAE Handbooks contains a pretty comprehensive list of the R/U values of various materials. All stone and all wood are pretty much the same. Make sure you read all of Appendix A and substitute your materials for some of the assumed materials where necessary.
From what I have read about the new website, it is no longer required to complete all design prerequisites before submitting for Design Review (split review assumed).
We have been hung up on submitting EAp2 because a photovoltaic array is planned for one of our projects, but it won't be designed until far into construction. It would be really great to submit the other design credits and know where we stand (it's a super-complex project with an unusual LEED project boundary.)
So is it now true that we can submit for Design review and defer EAp2?
You can defer design prerequisites and credits from the design review phase. This has always been the case. We routinely defer EAp2.
Appendix G Table G.3.1 - Service Hot water systems states "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:..." Does this mean that the size of the domestic hot water recirc pump should be the same size as the proposed design?
Any help is much appreciated.
A domestic hot water recirc pump is not a regulated component of 90.1, therefore it is a process load which must be modeled identically. So yes the same size pump should be modeled.
I have a question about the best software choice and modeling strategy for water-source VRV (or VRF) systems.
Our proposed design will use a water-source variable refrigerant volume system with refrigerant heat recovery. The office building is a three story rectangle with long north- and south-facing exposures. Due to capacity limitations, each floor will be split onto two VRV condensing units, one serving the east half, and one serving the west half, so that each VRV system utilizes refrigerant heat recovery between the north and south faces. Along with the six VRV condensing units, dedicated outdoor air 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. units will also be tied to the same water loop. The water loop will have variable primary pumping. The temperature of the water loop will be maintained by a gas-fired condensing boiler and a dry cooler on the roof.
We have immediate access to Carrier HAP and eQUEST modeling software. HAP can model air-source VRV, but it cannot explicitly model water-source VRV, so I tried some alternate methods. First I approximated our design in HAP as a WSHP system, hoping that the heat recovery of our designed refrigerant systems would be captured on the modeled water loop, but the results did not reflect this. Also, the pumping energy of this modeled system appeared to be higher than it should have been, leading me to believe HAP was not accurately modeling the pumping turn-down. I then modeled in HAP an air-source VRV system with refrigerant heat recovery, and electric resistance auxiliary heating (the only option) in low ambient conditions. This reflected the refrigerant heat recovery performance but did not account for enough pumping energy, and the unloading performance of the modeled VRV condensing units responded directly to the ambient air temperature instead of the water loop.
For eQUEST, I've seen some documents that show how it may be possible to insert equipment performance curves from manufacturer's data into the .inp file to model water-source VRV. However, due to time and budget concerns, we would like to maintain just one model throughout the project for both load calcs and energy modeling. While I'm not as familiar with eQUEST, my understanding is that its capabilities are not strong at producing zone-level load results used for equipment sizing, so if we need to maintain a HAP (or other) file for loads anyway, eQUEST might not be the best option for the energy model.
While we don't yet own a Trane TRACE 700 seat at my current firm, we have also looked at purchasing this software as an option since I have some past experience with the program. CDS says TRACE cannot yet model water-source VRV explicitly, but they've seen users approximate the system by using an air-source VRV system and altering the condenser performance curves to reflect the water loop temperatures instead of the air dry bulb. My thought is we could then lump all the VRV units onto the same modeled system so that TRACE would account for refrigerant heat recovery of the entire system, approximating how our water loop would recover heat between the condensing units. TRACE would also allow us to obtain load calcs and system sizing from the same model.
Does anyone have experience modeling this system? What is the best software to use? Have you submitted this system for credit EAp2? It seems like, due to the limited availability of software programs that can accurately model the system, LEED reviewers should have some precedent to fall back on as far as accepting approximate modeling methods. If you have submitted using a work-around, what did you run into?
Thanks for the help.
We have not modeled this system yet or seen one submitted for LEED. Based on our experience with modeling VRF systems and reviewing LEED submissions I would say that your best bets to model this as accurately as possible would be either Trace or EnergyPlus.
Thanks, Marcus. Which interface do you recommend for EnergyPlus?
We have used Design Builder. I am not as familiar with the others.
You've probably already selected an approach, but I'll post my three cents for the benefit of others in a similar situation. I'll call these practical application considerations.
1) Load calculations typically include a different set of assumptions compared to simulation tools so while you have the potential to save some money by not switching tools, you also have the potential to experience cost overruns by trying to use the least compatible tool for the job.
2) Conversely, trying to learn a new simulation tool on the fly is also a recipe for surprises and cost overruns.
3) Regardless of the tool chosen, 90.1 allows you to perform "exceptional calculation measures" for things that can't be directly characterized within the model.
I admit the first two bullets are contradictory, but these are important to consider if one is getting into the energy simulation business.
We are modeling a new building in a previously developedPreviously developed sites are those altered by paving, construction, and/or land use that would typically have required regulatory permitting to have been initiated (alterations may exist now or in the past). Previously developed land includes a platted lot on which a building was constructed if the lot is no more than 1 acre; previous development on lots larger than 1 acre is defined as the development footprint and land alterations associated with the footprint. Land that is not previously developed and altered landscapes resulting from current or historical clearing or filling, agricultural or forestry use, or preserved natural area use are considered undeveloped land. The date of previous development permit issuance constitutes the date of previous development, but permit issuance in itself does not constitute previous development." site, with some remains of the previous building.
One of the project strategies is to step aside the building façade (2 m, approx) and maintain one of the existing façades, conforming a covered patio that will act as a double skin façade.
In your opinion, should we model the previous external façade in both, baseline and proposed buildings?
As a bioclimatic project strategy, could we model it only in the “proposed” building?
Thanks in advance
Very hard to say specifically what you should do with the limited information.
I would always do a double facade as an exceptional calculation. There are several areas of the modeling protocols that are potentially violated (i.e. identical building area, identical vertical fenestration area, ventilation rates, etc.). For a true double facade the space between the glazing should be unoccupied space and separately ventilated.
We did a new building double facade that was approved for LEED. The baseline was without the double facade and the proposed was with it included. Since we did it as an exceptional calculation we had to create two different proposed models, one with and one without the double facade.
Your situation is somewhat further complicated by the fact that it is an existing building. I am not sure what you mean by "some remains of the previous building", but you can sometimes claim the existing conditions in the baseline under Table G3.1-5 Baseline (f). Very hard to answer your questions without seeing the specific situation.
I know it is difficult to assess about a complex solution with so little information. I appreciate your advices.
The existing perimeter wall acts as a mask, because of the project decision of spacing the real façade and creating a buffer area. I guess that might be equivalent to a new building with a double skin.
Perhaps the existing wall (the so called "remains of the previous building") can be modeled only as solar mask in the "baseline" and as a part of a complex double skin in the "proposed".
In any case, thanks for your feedback.
Hello, My name is Ricardo from Mexico City. We have a Project that include Hotel, Residential Building and Retail.
On the case of Residential Building in Mexico City we dont install HVAC Systems because the Mexico weather dont required Cooling and Heating systems. For compliance of IEQ-PR-01 we will install outside air system for compliance of the prerequisite.
In the case of retail and hotel, we have HVAC systems and we will model these buildings according Appendix G of ASHRAE 90.1-2007.
How I must model the energy model for the compliance of EA-PR-02 of Residential Building?
I would model the baseline and proposed identically based on the proposed. Be sure to provide an explanation.
Shall the person who enters his/her initials under signatory section ( for example EAp2-1, 2-2, 2-3 ) be registered mechanical engineer (PE) ? If so, can you please let me know where this requirement is stated ? There are (2) mechanical engineers are working on the project. They shared the credits and placing their own initials to each credit even though PE overview every document.
The signatory does not have to be a PE.
Thanks Marcus. Is there any statement or line in the Design Guide or LEED online to back up this if someone say other way around and I have to prove it ?
The signatories are actually no longer enforced in the review process so you will not be asked to prove anything. In the past when it was enforced the reviewers did not even look for the credential of the signatory. If you can't find anything that says it has to be a PE, then this is proof enough.
Try this link:
Is Table 10.8 mandatory for plug fans of new buildings? The fans are installed in Air Handling Units. If they are mandatory, are they mandatory both for supply fans and for return fans?
Yes the minimum efficiency applies to all HVAC motors 1 HP and up.
Thank you, Marcus. You wrote "motors". Shall we consider the efficiency of Table 10.8 only as the motor efficiency, i.e. the "mechanical power exiting from the motor" / "electric power absorbed by the motor" ratio? I mean, shall we not consider also the fan efficiency, i.e. the "air hydrodynamic power" / "mechanical power exiting from the motor" ratio, in order to verify the mandatory provision?
Other issue: when Table 10.8 writes "Motor kilowatts" shall we consider the mechanical power or the electric power?
Table 10.8 lists the motor efficiency and that is all you must comply with.
The electrical power I think.
Thank you Marcus, but... new year, old issue...
The note of Table 10.8 states: "Nominal efficiencies shall be established in accordance with NEMA Standard MG1". If the motors are not classified according to that standard, but according to IEC 60034-30, how could the mandatory be verified?
The motors are classified IE2 and have inverters. Can the increase of efficiency due to the inverters be considered?
The project is located in Italy. Could I find some alternative compliance paths for Europe for the mandatory provision for fan motors?
I have not attempted to compare the two standards. You have a couple of options - do the comparison yourself so that you can say that you definitively meet this mandatory provision or just assume that the standards are roughly equivalent and indicate that you meet this mandatory provision. One thought is are the motors in question ever exported to the US? If so then they would likely have to meet the NEMA Standard. Perhaps the motor manufacturer could be of assistance.
I can tell you that the motor efficiency mandatory provision is rarely even evaluated during the LEED review as there is no reporting associated with it.
The European LEED ACPs outline a process for trying to determine equivalency with 90.1. I think the intention was to determine equivalency at the whole building levels and not necessarily at the component level.
I am working on a project (2 story office building) as a LEED AP & architect and received Preliminary Design Package comments from GBCI. One of the comment was about the building's gross square footageSum of the floor areas of the spaces within the building including basements, mezzanine and intermediate-floored tiers, and penthouses with headroom height of 7.5 ft or greater. It is measured from the exterior faces of exterior walls or from the centerline of walls separating buildings, but excluding covered walkways, open roofed-over areas, porches and similar spaces, pipe trenches, exterior terraces or steps, chimneys, roof overhangs, and similar features. (6219 in Plf2) does not match to energy model square footage. Mechanical engineer revised his calculations for the final design package submission and brought up his sqf from 5005 to 5812 sqf however his model still does not include the walls. Mechanical engineer told me that he can not include the walls and left his sqf at 5812. It makes sense that he did not include the walls but I am not sure how GBCI will interpret this. I know that all square feet information throughout a project should be consistent but in this case, GBCI should have some sort of exception. Please share your experience and suggestions. Thanks
Consistent and identical are two different things.
Some energy modeling software (but not all) uses the net square footage instead of the gross square footageSum of the floor areas of the spaces within the building including basements, mezzanine and intermediate-floored tiers, and penthouses with headroom height of 7.5 ft or greater. It is measured from the exterior faces of exterior walls or from the centerline of walls separating buildings, but excluding covered walkways, open roofed-over areas, porches and similar spaces, pipe trenches, exterior terraces or steps, chimneys, roof overhangs, and similar features.. For PIf2 you are supposed to enter the gross square footage. For an energy model using net square footage you can enter the net square footage in EAp2. In general the net sf should be within 10% of the gross sf. Looks like the reason that the original areas were questioned. Looks like you should be OK with the revision.
I am not sure whether to class mechanical rooms which are free cooled by outside air as "conditioned" for the purpose of the baseline (so the baseline would be on system 5 in this example). They are being maintained to 85oF through the use of an 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. (no heating or cooling coil).
No heating or cooling system means that the space is unconditioned.
For some external lights the LEED team claimed the LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org. 10236 for SSc8, i.e. the lights were not considered because:
Street lighting that is required by governmental authorities to be installed within the LEED project, specifically for the purposes of lighting a public street, does not need to be included in any of the calculations. Project teams should provide documentation of the government requirement and a narrative describing the application of this exemption to the project.
That interpretation doesn't mention prerequisite EAp2, therefore I think that I have to consider those lights in the energy model, haven't I? Shall the relative lights in the baseline model be modeled as normal external lights (i.e. according to Table 9.4.5) or as process energy (i.e. the wattage of the baseline model is equal to that one of the design model)?
Existing exterior lighting within the LEED project boundary connected to the project (or any adjoining project on a campus project) should be modeled identically in both models. If the existing lighting is not at all connected then it should not be included in the models at all.
Our project consists of renovation of 140,000 SF of an existing building, as well as the addition of 30,000 SF of new space. For whole building energy simulation, I see minimum requirement of 10% improvement for new buildings and 5% for major renovations. I'm trying to determine which requirement applies to our project - can our project be considered as a major renovation, or it has to be considered as a new construction?
It is both.
The percentage savings related to the points will be based on a weighted average of the new vs existing. The EAc1 form automatically calculates the percent savings and awards the correct points. In your case the savings threshold for the first point would be 5.88%.
For an existing building under major renovation would the mandatory provision 126.96.36.199 for vestibules be still applicable even if the project scope does not include any additions or plan modifications?
In general if you are not replacing or modifying the system in question you do not need to meet the mandatory requirements related to that system. So I do not think this would be required.
Thanks Marcus for pointing this out!
The overall process load of our project turns out to be in the vicinity of 15% only. We are aware that 15% is absurdly low and unusual for plants. The factory owner, nevertheless, sent us a full array of appliances and affirmed the list is determinate.
Should I just proceed with the obtainable data and have the factory owner undersign the equipment list so as to substantiate the data?
Thank you very much.
Could you visit the factory, to see all the equipment, plants, etc...?
Could you get bills, in order to analyse the real energy requirements?
I got such a low process load consumption for a school and I explained it with a narrative, but for a factory it seems strange. Are the machines very few in comparison with the building surface? What are the main end uses (heating or cooling, or lighting, or ventilation?).
What does the factory make? Some processes are far more energy intensive than others.
It could be possible to document a low process load, so you can proceed as you suggest. If it were me I would be asking the factory owner a whole bunch of questions about the equipment if I had any doubts about getting it all. Make sure to thoroughly document the actual installed equipment as this will be viewed by the reviewer with considerable suspicion.
Thank you so much for all the suggestions. The factory is under construction and will manufacture cosmetics as soon as the construction concludes. The owner invariably asserted all the machines had been incorporated.
The owner's substantiation may dispel the reviewer's doubts. In any case, we are a little apprehensive about the discrepancy.
A good place to look is on the electrical equipment schedules...the electrical engineer has to plan after all and requires a list of electical equipment with connection and usage power.
The project is a medium sized workshop shed and will be mechanically ventilated with fans with a particular air change per hour as per the local standards. The client wants this to be LEED certified building and we wanted to check what should be the right approach towards energy modeling to meet the EA Prerequisite 2 and EA Credit 1. Normally for a naturally ventilated building we would follow the approach mentioned in the Advanced Energy Modeling Guide, Appendix D. However this is not a naturally ventilated space, though there are windows opened to allow the air changes, with mechanical fans to meet the ventilation requirement. Shall we then model the base case with the same ventilation fans as the design case and prove compliance. Please let us know which 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/ guide could tell us more about this. Please advise.
G188.8.131.52 Ventilation: "Minimum outdoor air ventilation rate shall be the same for the proposed and baseline building designs".
Actually I model exactly the same ventilation flows and the same schedules in the two models, for every hour. What does "minimum" mean in this case?
I know that an exception could be when in the proposed building there is Demand Control Ventilation.
The fans are modeled as designed for the proposed model, according to G184.108.40.206 for the baseline model.
I hope this is useful to you.
If the space is heated then the baseline should be modeled as a system 9 or 10 under addendum dn to 90.1. The fan power in the baseline 0.3 watts/cfm.
If the space in unconditioned then the ventilation fans are considered a process load and modeled identically.
The standard requires the same infiltration and window ventilations be employed on both models. I would not recommend trying to take credit for window, "natural", or infiltration ventilation unless you are an expert and have a lot of time to prove your case.
Thanks for your prompt response.
For your information, we have considered an air-change of 15 achAir changes per hour: The number of times per hour a volume of air, equivalent to the volume of space, enters that space. for effective ventilation for the shed.
There is no demand control ventilation and no heating. The windows shall be kept open to facilitate this 15 ach ventilation. This is may be comparable to mechanically assisted natural ventilation.
Shall we model the baseline with the fans as process load but without any baseline air-conditioning system and likewise for the design case.
Or do we have to model the baseline with the baseline HVAC system types with the 15ach ventilation rate and similarly for the design case. This approach due to the very large ventilation rate will give us absurd figures.
We would like to meet only the prerequisite and not try for any points.
Request your advise and are there any references to ratify this approach ?
This is an unconditioned space so any energy use associated with ventilation should be identical in both models. The fan power and ventilation rate would therefore also be identical. No HVAC required in the baseline for an unconditioned space.
May I request any reference document mentioning this.
I am not sure if there are any interpretations that address this but I would have to search them just like you.
Quite often these kinds of issues are not directly addressed but must be determined based on definitions and a connect-the-dots interpretation of 90.1. In this case these fans are not regulated so it is kind of hard to point you to something that is not addressed by the standard in question.
Thanks for your prompt response Mr. Marcus Sheffer
I am doing energy simulations for a factory. I am seeking advice as to the following situation:
1.) Part 1: Load Estimating, Chapter 7 of the classic Carrier Manual states that “a properly designed positive exhaust hood reduces the sensible and the latent heat gains by 50%”. Supplemental data is shown in table 7 – Heat gain from miscellaneous appliances.
Inquiry: Could I simply multiply the appliance wattage by 0.5 to obtain room sensible heat gain?
2.) The factory equipment takes a substantial portion of cooling demand. Therefore, the HVAC designer proposes once-through configuration of supply airflow to equipment room. That is, no room air in equipment room will return to the air handler and end up as a load on the chiller plant. The designer calculated the amounts of exhaust air and make-up air associated with the hood that will keep up desired pressure differential across the room enclosure.
For instance, 4-kW equipment should impose 2-kW heat gain. Suppose that the 2-kW heat gain will warm up the supply air temperature from 13.9 ⁰C (57 ⁰F) to 25 ⁰C (78 ⁰F). The room air at 25 ⁰C (78 ⁰F) will be constantly discharged through the hood whenever the hooded equipment runs.
Inquiry: Regarding energy simulations, could I entirely eliminate the heat gain from hooded equipment as the once through configuration is utilized together with hood? Just additional fresh air load is relevant because, for example, 250 l/s (500 cfm) of once-through make-up air to equipment room is equivalent to 250 l/s (500 cfm) of fresh air to the air handler.
I am grateful for all the advice.
1. Maybe. We would recommend that you double check the Carrier guidance with the guidance in the latest ASHRAE Fundamentals Handbook. There is guidance on hooded and not hooded heat gains.
2. The equipment is still a cooling load in the space, even though it is not a load directly on the cooling coil. it can be reduced but not eliminated entirely. When reducing it you should provide an explanation for how you determined the level of reduction.
We have a rough time seeking to reduce supply fan energy during energy simulations. Could anybody throw some light on the following account:
1.) The project on hand is a plant that strictly regulates pressure differences among interior spaces.
2.) The proposed design reckons with a VSD on the air handler fan to adjust fan speed as airflow drops due to loaded filters, clogged cooling coils, etc. In contrast to generic VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. systems, the VSD on the air handler fan is not designed to vary supply airflow in proportion with room sensible heat.
3.) System 6 requires that the fan control be VAV. As far as I am concerned, the VAV of system 6 does not reflect the actual operation since modulating the supply airflow according to the room sensible heat may not concomitantly control the relative pressure differences among interior spaces.
4.) As a consequence, the fan energy of the proposed design is considerably higher than that of the baseline case.
Is the table G3.1.1B in Appendix G an ironclad rule to follow?
Is it relaxed in case the baseline is not comparable with the actual operation?
Is there a minimum flow of VAV deemed effective to maintain relative pressure differences among internal spaces?
In the event VAV is applicable to the factory in question, I suspect that both the proposed and baseline fans may not save significant energy, not to mention a barrage of pressure sensors and complex controls to make the system run as intended.
Thank you very much in advance for all the responses.
Yes you must follow Appendix G generally without exceptions.
I would suggest you see if G3.1.1 Exception (c) applies to your situation. If it does then your 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. issue goes away.
In general make sure you are not trying to get the baseline system to actually function the same way as the proposed. Quite often the baseline system configuration will not actually work in the real world.
Thank you very much indeed, Marcus. Your suggestion hit the bull's eye.The exception (C) under G3.1.1 is germane to our situation.
The factory under consideration has three (3) levels of pressurization at 12 Pa (0.05”), 25 Pa (0.1”), and 38 Pa (0.15”).
A multitude of spaces are pressurized to maintain 12.5 Pa (0.05”) and these spaces are contiguously located. Concerning the baseline case, am I allowed to lump these spaces together and cool them by a good-sized PSZ-HP (packaged 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.) of system 4? In other words, this single zone consists of multiple spaces.
Does each space need to be equipped with a PSZ-HP, making every zone a 1-space zone?
See G3.1.1. For a system 4 you need to map the systems to the proposed systems. Also see Table G3.1-7 about thermal blocks.
In the project I'm modeling (C&S), I took the opportunity to use the CS 2009 EAp2-c1 ACP spreadsheet with integrated calculator.
I've come to reach 46% of Energy cost influenced by CS Owner. The spreadsheet (together with the necessary explanations) could be uploaded in EAp2 and also in EAc1 form upon ACP section.
The question is: How to enter the revised points (for example 7 instead of 5). I don't see such place on the forms. The same question is also for the renewable energy, because it should also be influenced by the same percentage.
It depends on what version of the form you are using (v3, v4 or v5).
I don't think you have to enter the revised points. The reviewer should be able to figure it out and award the correct number of points.
According to ASHRAE 90.1-2007 Table G3.1.5 (f) for existing building envelopes, the baseline building design shall reflect existing conditions prior to any revisions that are part of the scope of work being evaluated. Does this mean that for an existing fully glazed building (80% of gross above-grade wall area) the baseline building will meet the same portion of fenestration (80%)?
The Green Engineer, LLP
EAc1 relies directly on the EAp2 documentation, and the strategies to earn the prerequisite are often similar to earning points under the credit.
Limits on interior and exterior light use can help in reducing energy loads.
Daylighting reduces demand on installation and use of lighting fixtures resulting in energy use. To full realize the energy benefits, contorl electrical lighting with daylight sensors.
Commissioning of energy-efficient building systems helps realize he operational benefits of the design.
Onsite renewable energy contributes to prerequisite achievement if pursuing energy modeling under Option 1.
The computer model developed for EAp2 – Option 1 is used in the M&V plan.
Do you know which LEED credits have the most LEED Interpretations and addenda, and which have none? The Missing Manual does. Check here first to see where you need to update yourself, and share the link with your team.
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