EAc1: Optimize Energy Performance is, by far, the most important credit in LEED, based on the number of points available. Up to 19 points are at stake here based on how much you’re able to reduce the project’s predicted energy cost. That large amount of points also reflects the great importance LEED places on reducing energy use and forestalling climate change1. Climate change refers to any significant change in measures of climate (such as temperature, precipitation, or wind) lasting for an extended period (decades or longer). (U.S. Environmental Protection Agency, 2008)
2.The increase in global average temperatures being caused by a buildup of CO2 and other greenhouse gases in the atmosphere. This temperature change is leading to changes in circulation patterns in the air and in the oceans, which are affecting climates differently in different places. Among the predicted effects are a significant cooling in Western Europe due to changes in the jet stream, and rising sea levels due to the melting of polar ice and glaciers..
You have some options to choose from. For certain buildings types you can opt to skip the energy modeling option and simply follow a list of prescriptive requirements, but you can’t earn nearly as many points that way, and you won’t have the benefit of the energy simulation to guide you to the most cost-effective energy efficiency measures.
This credit is documented in concert with EAp2: Minimum Energy Performance. Refer to EAp2 for detailed steps on LEED compliance and documentation.
An energy-efficient building can cost more to build, through components like efficient mechanical equipment and high-performance glazing. On the other hand, those same higher-cost measures can generate savings by reducing the size of mechanical systems. And of course, dramatic financial savings can come during the operational phase. Energy modeling can help determine the “sweet spot” for your project.
Your project may also qualify for financial incentives offered by utilities or local, state, and federal authorities, that help offset the premiums of system upgrades and renewable energy implementation. In many states, utilities or other local entities provide financial incentives in the form of rebates or tax breaks to alleviate the cost premiums associated with installing systems and purchasing equipment geared toward energy efficiency. (See Resources for incentives.)
Documentation for this credit happens along with documentation for the associated prerequisite, EAp2: Minimum Energy Performance. In fact, for the prescriptive options, all you have to do is document the prerequisite—no further information is required to earn a point under the credit.
Three compliance options are available.
With clearly defined goals and committed team members, your project should be able to achieve an energy cost reduction of 10% to 15%, through measures such as the following.
If you want to aim for higher targets of 20%–50% energy savings or higher, consider measures such as the following.
The most cost-effective measures vary by building type and location—refer to ASHRAE Advanced Energy Design Guides and case studies for appropriate strategies in your building. (See Resources.)
Building energy performance is a result of interactions between various different building components and systems. The mechanical system consumes energy based on factors such as architectural design, operating schedules, programming and climate. To significantly reduce energy it is very important for all team members to share design ideas and collaborate on strategies. The integrated design process will support constant communication, fast response on new ideas, and can help eliminate misunderstandings or assumptions—consider using it as a central strategy to earning points for this credit.
If your project is connected to a district energy system, LEED 2009 lets you take advantage of improved system efficiencies. Although not permitted for use with EAp2, you may include the improved efficiency over baseline of the district energy system in the energy model you develop for EAc1. In this scenario, you develop a separate model from the one for EAp2 compliance. (See Resources for more details through the updated guidelines.)
This credit is documented in concert with EAp2: Minimum Energy Performance. Refer to EAp2 for detailed steps on LEED compliance and documentation.
Begin identifying a target for energy performance. Begin by researching similar building types using the EPA Target Finder program. An Energy Star score of 80 or higher will typically earn EAc1 points.
To earn points for EAc1 you’ll most likely have to significantly exceed your local energy code. Achieving this energy reduction requires special attention to detail by your entire team from the beginning of the design process, and dedicated leadership from the owner.
Note that energy efficiency is not just about efficient boilers and chillers. To achieve high targets, the design of the building has to help reduce dependence on mechanical heating and cooling throughout the year, through measures like orientation, moderate glazing areas, and self-shading.
An automated building management system (BMS) can significantly reduce building energy use by turning down air conditioning and turning off lights during unoccupied hours, along with other similar measures. Occupancy sensors, timers, and temperature sensors feed into the system to switch off lights and fans when not needed. Note that controls can be counted towards energy reductions only through energy modeling.
The compliance paths for this credit are the same as for EAp2. Because the documentation is identical, it makes the most sense to consider credit implications when selecting the appropriate compliance path for the prerequisite.
Complying with Option 2 earns only one point, and with Option 3, 1-3 three points. If you are committed to greatly reducing energy usage and earning a higher number of points, then follow Option 1 for both EAp2 and EAc1.
Renewable energy shows the contrast between Options 1 and 3. Installing a renewable energy system for 5% of electricity use earns one-third of a point through Option 3. Installing a renewable energy system to reduce building energy costs by 2% earns one point under Option 1.
You can earn up to 19 points through EAc1, Option 1, using the same methodology as for EAp2, Option 1.
Only one point is available through Option 2: Prescriptive Compliance Path: ASHRAE Advanced Energy Design Guide, but if you choose this path for EAp2, it is earned automatically and does not carry any additional requirements. This option is available to office or retail projects up to 20,000 ft2 or warehouses less than 50,000 ft2. 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.)
Up to three LEED points are available under Option 3 for compliance with the Core Performance Guide. It’s a good option if your project is smaller than 100,000 ft2, does not fall into one of the Option 2 categories and you’d rather not commit to energy modeling (Option 1). Your project automatically earns one point for meeting the prerequisite. An additional one or two points are available for meeting any three or six requirements, respectively, of Section 3. These requirements range from installing a renewable energy system to adding filters to air-handling systems. Review these requirements with your team to select the three or six that are most applicable to your project.
Some energy conservation measures, such as energy recovery ventilation or a highly insulated building envelope, add to both construction and design costs, though with an integrated design process these costs might be recouped through savings elsewhere, such as through reducing the size of the mechanical system. The most effective approach is to have your building owner and design team together evaluate both the first costs of the energy-saving measures and their effectiveness at reducing operating costs.
If you are connected to a district energy system, you are better off pursuing Option 1, because only through energy modeling can you benefit from the efficiencies of the district energy system.
The model you need to develop for EAc1 is the same as for EAp2 (unless you’re on a district energy system).
Follow the guidelines on identifying energy-efficiency strategies to achieve the owner’s energy efficiency goals per the Owner’s Project Requirements, developed for EAp1: Fundamental Commissioning.
Your mechanical engineer and energy modeler need to work in collaboration with the architect when finalizing building form, façade treatment, and programming—to give real-time input on the energy impact of all the design features.
Consider highly efficient systems like heat pumps for heating and cooling, district energy and cogeneration, ice storage for off-peak cooling, or energy recovery ventilation—to attain a substantial energy reduction of 10%-20%.
If your building includes the use of purchased steam supplied to your HVAC system, the proposed (design) building is modeled as if the steam system is “located” in the building— with the same efficiency with which it typically operates. The designed building is allocated only the fuel cost (for natural gas or oil) required to generate and deliver the steam needed for the building. The steam purchased is actually considered “free,” as steam rates are not included. And here is where your building really benefits—if the steam system also co-generates electricity along with steam, that electricity is assumed to be “free” to the proposed building, as well. (Refer to the latest guidelines from USGBC.)
Energy-efficient design can increase your construction budget. Use your computer model to optimize packages of upgrades that balance any added costs against cost savings, and run payback analyses to identify the most cost-effective options.
Even if you’re using Option 1, refer to the Advanced Energy Design Guides and Core Performance Guide (referenced by Options 2 and 3) for ideas on cost-effective measures to implement.
If you complete the documentation for EAp2, Option 2, you automatically earn a point through EAc1. The requirements are identical to EAp2 and require minimum additional time on the part of your engineer.
If you meet the prerequisite through Option 2, and document it, you earn a point through the credit—it’s that simple.
If you complete the documentation for EAp2, Option 3, you earn one point through EAc1, Option 3. The requirements are identical with EAp2 and requires minimal additional time on the part of your engineer.
Review Section 3 of the Core Performance Guide to identify three or six of the 11 available strategies (for one or two points, respectively) to pursue.
If you are installing a renewable energy system that provides at least 5% of your electricity, you already implemented one of the three strategies from the Core Performance Guide.
If you meet the prerequisite, and document it, you achieve one point —it’s that simple.
Note that the credit language excludes three of the strategies of the Core Performance Guide from helping you earn the credit. This is because these areas are covered thoroughly by other LEED credits.
Select those strategies that are most suitable for your project type and location. For example, evaporative cooling is very effective in a hot, dry climate but is not likely to be a good idea in the cooler, damper Northeast or Northwest. The list is a good summary of the best ways to reduce energy intensity, though some strategies may be more effective in offices and museums, while others are more helpful in hospitals and hotels.
Develop multiple iterations of your project design to analyze the energy impact of each change.
Further develop energy optimization strategies with the design team. Look at reducing loads while creating a comfortable environment within the shell. Look at reducing east and west exposures, and at providing south windows with exterior shades to make a design feature out of passive techniques. Discuss highly efficient system design at this stage, before your design is finalized—for example:
Ecotect and IES Virtual Environments, among other software tools, allow very quick analysis of alternative building forms and mechanical systems, allowing you to test alternative ideas, and develop a single idea in an iterative design process. (See Resources.)
Google SketchUp is good for shading studies, and plug-ins are available for IES and EnergyPlus to support energy analysis of Google SketchUp models.
Ventilation is one of the largest energy end-uses. Look at alternative means of ventilating your building. Consider naturally ventilated spaces, mixed-mode ventilation for moderate climates, and demand-controlled ventilation for mechanically ventilated spaces.
Daylighting makes for welcoming spaces, and can save energy both through reduced electric lighting and reduced cooling load due to the reduced electric lighting. Consider an atrium and skylights to serve ventilation and light functions. Integrate spatial programming within the atrium to utilize the space. See LEEDuser’s daylighting strategy for more.
Consider other techniques to upgrade the building envelope and insulation, such as:
By this stage, the architect should have seen a visual presentation by the energy modeler on multiple building forms with energy-use comparisons. This will help hone in on the most energy-efficient design that also supports the building program.
Follow EAp2 steps for compliance and documentation.
If you are pursuing an additional point or two by complying with Section 3, select the strategies you anticipate pursuing.
Some easily implemented strategies include:
One complete run of your energy model should be completed during design development to make sure the design is reducing annual energy cost by your targeted amount. This is the time when simplified models used to inform early design decisions should be replaced by a more comprehensive detailed model. Run two or three alternatives to help the designers finalize envelope and system selection. Common measures to consider include high-performance windows, additional roof insulation, and more efficient boilers.
Use your energy model to review envelope thermal and hygrothermal performance. In a heating climate, thick insulation inside the air barrier may cause condensation problems. Consider an exterior thermal barrier to protect the air barrier and to prevent condensation inside the wall cavity. Identify thermal bridges in the walls and windows that could leak heat from inside. Add thermal breaks, such as neoprene gaskets, on shelf angles, silicone beading on window frames, and use other techniques to prevent leakage from the envelope.
Your energy model can be a supportive design tool that provides insight into the actual performance of the building envelope and mechanical systems. It can highlight surprising results, such as a prominent feature like an efficient boiler contributing only a 1% reduction in energy cost. It can also provide evidence to support operational energy-use decisions such as changing the heating or cooling set points a few degrees.
The baseline exterior lighting power allowance (ELPA) may not take credit for any category which does not have any lighting fixtures in the proposed building, or for any area or width within any category which is not lit in the proposed building, even within the tradable categories. In addition, the lighting for a single building component cannot be counted within two separate categories in the baseline ELPA calculations.
Make sure the identified measures are being implemented. For Section 3 items, check with the mechanical engineer on the status of each measure. Document the measures if they are completed, like daylight control locations and quantities and economizer performance.
Finalize the design, including all energy system strategies. Make sure your project is on track for the target rating based on energy cost.
Assess your compliance with the credit and projected points to be earned. This credit and option can be the largest contributor to your LEED point total, so if you aren’t hitting your goal, consider last minute design changes now.
Specify and contract for efficiency measures. Often new equipment and novel systems are unknown to contractors, so hold bid and construction meetings to ensure your specifications are understood and everything is purchased and installed as intended.
The more thorough your drawings and specifications are, the less the chances of incorrect installation.
Contracting with a commissioning agent for the expanded scope of EAc3: Enhanced Commissioning is highly recommended. Any project relying on sophisticated controls and systems for energy efficiency needs the eye of an experienced commissioning agent during construction and functional testing.
Energy systems are only as efficient as they are well-installed and operated—involve the operations team during the final Construction Documents phase (or even much earlier) to make sure they are abreast of design decisions and prepared to operate in the sequence required.
Make sure mechanical spaces and locations are coordinated in the architectural and structural drawings. For example, is a duct run colliding with a beam? Is a fan coil unit placed above a door opening so that it will leak condensate on people walking into the space? Common mistakes like this can cause construction delays and poor performance during operations if not detected, so coordination of the drawings is critical, especially if your project involves integrated design and complex systems.
When your final design is documented, run a final energy model for LEED documentation. Include the specifications and efficiencies of the system being purchased and installed.
Finalize the list of strategies adopted from Section 3. Your project earns one point for three strategies, two points for six strategies.
All the design work is implemented during construction. Have the project architect ensure that the glazing is per your specifications and that the façade system incorporates a continuous air barrier. The commissioning agent will ensure all equipment purchased is exactly what the engineer required, and that all pumps and fans meet the specifications.
If you are installing a BMS, configure and program it to specifications. If there was any change in system specifications, make sure it is accounted for in the BMS programming.
If you are installing sensors and controls, they should be configured per specifications. Surprisingly, these are occasionally mis-calibrated or even reversed, causing discomfort to occupants, cost to the owner, and system malfunction.
Although EAc1 is a Design Phase submittal, it may make sense to submit the credit after construction for LEED certification to take into account any final design changes.
Make sure that the documentation from the prerequisite (EAp2) is complete in LEED Online. The documentation for EAc1 is, for the most part, automatically filled out in LEED Online based on your entries for EAp2.
Install all equipment as required by the design specifications.
If your team is installing features like VAV or a peak-load demand response system for the first time, check the installation and functional testing carefully. Get the vendor involved in writing the specifications to reduce risk of errors.
The first year of operations is usually a learning period for both the occupants and the facility manager. If your project underwent enhanced commissioning and developed an operations manual, you will have fewer miscommunications and untrained staff. Most medium and large projects install a BMS that centrally controls fans, pumps, part of the chiller and boiler load, and provides real-time energy-use data. Note that certain configurations require resetting, per feedback from users and the system itself.
Excerpted from LEED 2009 for New Construction and Major Renovations
To achieve increasing levels of energy performance beyond the prerequisite standard to reduce environmental and economic impacts associated with excessive energy use.
Select 1 of the 3 compliance path options described below. Project teams documenting achievement using any of the 3 options are assumed to be in compliance with EA Prerequisite 2: Minimum Energy Performance.
Demonstrate a percentage improvement in the proposed building performance rating 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 according to 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. The minimum energy cost savings percentage for each point threshold is as follows:
Appendix G of Standard 90.1-2007 requires that the energy analysis done for the building performance rating method include all the energy costs associated with the building project. To achieve points under 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 (e.g., for the interior, parking garage, surface parking, façade, or building grounds, etc. except as noted above), heating, ventilating, and air conditioning (HVAC) (e.g., for space heating, space cooling, fans, pumps, toilet exhaust, parking garage ventilation, kitchen hood exhaust, etc.), and service water heating for domestic or space heating purposes.
For this credit, 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 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:
Points achieved under Option 3 (1 point):
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 maximize energy performance. Use a computer simulation model to assess the energy performance and identify the most cost-effective energy efficiency measures. Quantify energy performance 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, 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 equivalentstandard 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.
ASHRAE offers guidance for different levels of building energy audits.
ACEEE is a nonprofit organization dedicated to advancing energy efficiency through technical and policy assessments; advising policymakers and program managers; collaborating with businesses, public interest groups, and other organizations; and providing education and outreach through conferences, workshops, and publications.
ASHRAE has developed a number of publications on energy use in existing buildings, including Standard 100–1995, Energy Conservation in Existing Buildings. This standard defines methods for energy surveys, provides guidance for operation and maintenance, and describes building and equipment modifications that result in energy conservation. 2 publications referenced by this credit (ANSI/ASHRAE/IESNA 90.1–2007 and ASHRAE Advanced Energy Design Guide for Small Office Buildings 2004) are available through ASHRAE.
Energy Star is a joint program of U.S. EPA and the U.S. Department of Energy that promotes energy-efficient buildings, products, and practices.
The Solar Heating and Cooling Programme was established in 1977, one of the first programmes of the International Energy Agency. The Programme's work is unique in that it is accomplished through the international collaborative effort of experts from Member countries and the European Commission.
The New Buildings Institute is a nonprofit, public-benefits corporation dedicated to making buildings better for people and the environment. Its mission is to promote energy efficiency in buildings through technology research, guidelines, and codes.
The Building Energy Codes program provides comprehensive resources for states and code users, including news, compliance software, code comparisons, and the Status of State Energy Codes database. The database includes state energy contacts, code status, code history, DOE grants awarded, and construction data. The program is also updating the COMcheck-EZ compliance tool to include ANSI/ASHRAE/IESNA 90.1–2007. This compliance tool includes the prescriptive path and trade-off compliance methods. The software generates appropriate compliance forms as well.
This extensive website for energy efficiency is linked to a number of DOE-funded sites that address buildings and energy. Of particular interest is the tools directory, which includes the Commercial Buildings Energy Consumption Tool for estimating end-use consumption in commercial buildings. The tool allows the user to define a set of buildings by principal activity, size, vintage, region, climate zone, and fuels (main heat, secondary heat, cooling and water heating) and to view the resulting energy consumption and expenditure estimates in tabular form.
Non-profit organization aiming at design community to increase collaboration for designing energy efficient buildings.
International association of energy modelers with various national and local chapters.
The Low Impact Hydropower Institute is a non-profit organization and certification body that establishes criteria against which to judge the environmental impacts of hydropower projects in the United States.
The Building Technologies Program (BTP) provides resources for commercial and residential building components, energy modeling tools, building energy codes, and appliance standards including the Buildings Energy Data Book, High Performance Buildings Database and Software Tools Directory.
This online resource, supported by Natural Resources Canada, presents energy-efficient technologies, strategies for commercial buildings, and pertinent case studies.
This website provides details process to develop an energy model.
Research warehouse for strategies and case studies of energy efficiency in buildings.
An online window selection tool with performance characteristics.
DOE website with database of energy performance of buildings across US.
This website lays out design process for developing an energy efficient building.
This website is put together for architects with ideas on hundreds of ways to improve design for lower energy demand.
This document lists multiple web based or downloadable tools that can be used for energy analyses.
This webtool is a database of strategies and vendors for energy efficient systems.
Energy design tools are available to be used for free online or available to download.
This website lists performance characteristics for various envelope materials.
This is an online forum of discussion for energy efficiency, computer model software users.
This directory provides information on 406 building software tools for evaluating energy efficiency, renewable energy, and sustainability in buildings.
Weather data for more than 2100 locations are available in EnergyPlus weather format.
Weather data for U.S. and Non-U.S. locations in BIN format.
A web-based, free content project by IBPSA-USA to develop an online compendium of the domain of Building Energy Modeling (BEM). The intention is to delineate a cohesive body of knowledge for building energy modeling.
The Commercial Buildings Energy Consumption Survey (CBECSThe Commercial Buildings Energy Consumption Survey (CBECS) is a national sample survey that collects information on the stock of U.S. commercial buildings, their energy-related building characteristics, and their energy consumption and expenditures. Commercial buildings include all buildings in which at least half of the floorspace is used for a purpose that is not residential, industrial, or agricultural, so they include building types that might not traditionally be considered "commercial," such as schools, correctional institutions, and buildings used for religious worship. CBECS data is used in LEED energy credits.) is a national sample survey that collects information on the stock of U.S. commercial buildings, their energy-related building characteristics, and their energy consumption and expenditures.
ASHRAE writes standards for the purpose of establishing consensus for: 1) methods of test for use in commerce and 2) performance criteria for use as facilitators with which to guide the industry.
These guidelines are available as a free download or can be purchased as a printed manual of 390 pages.
This Standard Practice provides useful, practical guidance on the technical issues where current research and consensus opinion have advanced, including information on design elements that can produce both a productive and pleasant work environment.
This information is of particular benefit to building design practitioners, lighting engineers, product manufacturers, building owners, and property managers. Although the text emphasizes the performance of daylighting systems, it also includes a survey of architectural solutions, which addresses both conventional and innovative systems as well as their integration in building design.
EDR offers a valuable palette of energy design tools and resources that help make it easier for architects, engineers, lighting designers, and developers to design and build energy-efficient commercial and industrial buildings in California.
This ongoing project explores the effects of computers and other information technology on resource use.
The Handbook provides up-to-date coverage of lighting development, evaluation and interpretation of technical and research findings, and their application guidelines.
The Ninth Edition provides students and professionals with the most complete coverage of the theory and practice of environmental control system design currently available. Encompassing mechanical and electrical systems for buildings of all sizes, it provides design guidelines and detailed design procedures for each topic covered. It also includes information on the latest technologies, new and emerging design trends, and relevant codes and zoning restrictions-and its more than 1,500 superb illustrations, tables, and high-quality photographs provide a quick reference for both students and busy professionals.
This manual covers nearly all disciplines involved in the design, construction and operation of green buildings.
This website is a fast growing news portal for energy efficiency in buildings showcasing success stories, breakthrough technology or policy updates.
Bimonthly publication on case studies and new technologies for energy efficiency in commercial buildings.
This is a quarterly publication for the group of energy modeling.
This professional architects organization is a very good starting point for architects looking to start energy efficient design.
Fall 2008 guideline and performance goals developed by federal government.
Information about energy-efficient building practices available in EDR's Design Briefs, Design Guidelines, Case Studies, and Technology Overviews.
This manual is a strategic guide for planning and implementing energy-saving building upgrades. It provides general methods for reviewing and adjusting system control settings, plus procedures for testing and correcting calibration and operation of system components such as sensors, actuators, and controlled devices.
This weblink leads to NBI website to download the standard for free.
State of the art lighting research center at RPI provides all information terminologies of lighting design, strategies for efficient lighting and product reviews after experimental testing.
This 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.
ENERGY-10 is an award-winning software tool for designing low-energy buildings. ENERGY-10 integrates daylighting, passive solar heating, and low-energy cooling strategies with energy-efficient shell design and mechanical equipment. The program is applicable to commercial and residential buildings of 10,000 square feet or less.
This website includes information from the developers of DOE-2 and DOE-2 products, such as eQUEST, PowerDOE, and COMcheck-Plus.
This is the list of all software approved by DoE that can be used to run simulation for LEED purpose.
This is a tool available to download for envelope moisture analysis tool.
BIM is a popular design tool that allows collaboration among all team members and allows quick outputs of all analyses.
DesignBuilder is a Graphical User Interface to EnergyPlus. DesignBuilder is a complete 3-D graphical design modeling and energy use simulation program providing information on building energy consumption, CO2Carbon dioxide emissions, occupant comfort, daylighting effects, ASHRAE 90.1 and LEED compliance, and more.
IES VE Pro is an integrated computing environment encompassing a wide range of tasks in building design including model building, energy/carbon, solar, light, HVAC, climate, airflow, value/cost and egress.
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."
In your supporting documentation, include spec sheets of equipment described in the Option 1 energy model or Options 2–3 prescriptive paths.
Sometimes the energy simulation software being used to demonstrate compliance with Option 1 doesn't allow you to simulate key aspects of the design. In this situation you'll need to write a short sample narrative, as in these examples, describing the situation and how it was handled.
This is a sample building energy performance and cost summary using the Performance Rating Method (PRM). Electricity and natural gas use should be broken down by end uses including space heating, space cooling, lights, task lights, ventilation fans, pumps, and domestic hot water, at the least.
This spreadsheet lists all the requirements for meeting EAp2 – Option 3 and and EAc1 – Option 3. You can review the requirements, assign responsible parties and track status of each requirement through design and construction.
Option 1 calculates savings in annual energy cost, but utility prices may vary over the course of a year. This sample demonstrates how to document varying electricity tariffs.
This graph, for an office building design, shows how five overall strategies were implemented to realize energy savings of 30% below an ASHRAE baseline. (From modeling conducted by Synergy Engineering, PLLC.)
The climate zones shown on this Department of Energy map are relevant to all options for this credit.
This 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.
Documentation for this credit can be part of a Design Phase submittal.
Does anybody have experience with designing laboratories in California (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. 3)?
Our proposed model is currently showing a negative 15% savings due to excessive cooling and fan energy. Due to safety requirements, three of four AHUs are 100% OA constant volume units with no heat reclaim or VFDA variable frequency drive (VFD) is a device for for controlling the speed of a motor by controlling the frequency of the electrical power supplied to it. VFDs may be used to improve the efficiency of mechanical systems as well as comfort, because they use only as much power as needed, and can be adjusted continuously. on the exhaust. They serve laboratory spaces with high ACHAir changes per hour: The number of times per hour a volume of air, equivalent to the volume of space, enters that space. rates. Heat reclaim on the remaining office unit was ruled out because it did not show a realistic payback in the mild climate.
We are part of District Energy System (DES) with good efficiency, have a small heat reclaim chiller to mitigate process load, and an excellent lighting design.
I've been scouring Appx G, the Advanced Energy Modeling Guide, the District Thermal Energy Guide, this forum, etc. for applicable tips but have come up empty. Anybody have design and/or modeling tips to reduce our energy costs?
I haven't done a lab in CZ3, but I have done one in CZ2 and CZ4. I'm surprised cooling is one of your main issues. Typically it is heating and fan energy as a result of overcooling from the air change rates. Beyond employing some sort of air-side heat recovery, the main method of getting energy savings is to model controls via schedules that allow the air flow rate to setback based on occupied/unoccupied or sash position. Watch out for G3.1.1 exception d though. It requires your baseline to setback the exhaust and makeup air to 50% during unoccupied hours. It takes away some of the credit for modeling the controls.
Under ASHRAE 90.1 - G3.1.1 do I HAVE to use exception C for any zones having special pressurization relationships, cross contamination requirements, or code-required minimum circulation rates? In my case this exception has a negative impact on my model. Can i stick with system 5?
You must apply the exceptions under G3.1.1.
In an energy model for a LEED 2009 project it has been shown acceptable to model Baseline System Exceptions per ASHRAE 2010 G3.1.1 such as modeling a System type 9 or 10 for a heating only thermal zone. The exception in ASHRAE 2007 (G3.1.1 c) for using baseline single zone systems for zones that have code required minimum circulation rates was deleted in ASHRAE 2010 G3.1.1. Since this exception would no longer be allowed under a LEED Version 4 project, it would seem acceptable to follow ASHRAE 2010 and not model it in a LEED 2009 project. Is it acceptable to NOT model this exception (ASHRAE 2007 G3.1.1 c) since under ASHRAE 2010 it is no longer allowed?
Modeling a system 9 or 10 is allowed by addendum to 90.1-2007. If you can find an addendum to 90.1-2007 that eliminated exception c then you can use it. Keep in mind you must use it in its entirety. If it was not changed by addendum then you can't use it.
We've got an 11,000 square foot maintenance garage for trucks, modeling it under LEED and ASHRAE 90.1-2007. This is a tricky space.
It has more than 15 BTUH/SFT of heat so according to Table 3.1 it is not a "semiheated" space - it is a "heated" space. In the real world, it is heat only, no cooling. They use radiant floor heat.
According to Appendix G Table 3.1 1 B we have to simulate the space as both heated and cooled. We get in a lot of trouble real fast after that.
An automotive repair garage requires a huge (41,000 cfm in this case) exhaust fan. This is a gigantic cooling load. The program (Trace) wants to simulate the exhaust as if it entered through the air conditioning unit.
This is heading down the path of simulating a 41,000 CFM 100% outside air rooftop unit, in a space that in the real world has no air conditioning. Yow!
Now, if I say this is a "process" load, and just add the power for the fan as a process electrical load, without adding the airflow in the energy model, is that the correct way to do this? I see another related question below hinting at the same idea. Not sure I am approaching this correctly.
I'll stop you at the cooling. In a heated only space you have a couple of options. In some cases you could possibly model it as a system 9 or 10 (heated only). In cases where the space is not covered by a system 9/10 then you can set the cooling temperature set points so that the cooling never operates. Quite often if you just tell the reviewer you are aware of this work around related to temperatures and do not model the cooling system it should be accepted.
The workaround of setting the cooling setpoint to a very high temperature makes sense. That'll be my first approach. I think some conversations with the review team before turning this in will be critical to success.
Marcus, I forgot to mention this is LEED 2009 under 90.1 2007. The original version of this standard doesn't have systems 9 and 10, although I have just become aware of a July 24 2010 addendum which apparently addresses some of these issues. A brief scan of it shows we have a system 10 and 11, (no 9, apparently) and it has a building type called "Heated Only Storage" . System 11 would be a warm air gas fired furnace, appropriate to this situation. I don't know if we can apply this addendum (this is a heated only shop, not storage) or if it helps the situation at all.
The other part of the question - how to model a fan that is a process load? These fans can move a whopping amount of air, but there are gas detection sensors that shut them off unless turned on manually, or various gases are detected - combustible gases, diesel combustion products, not just CO2Carbon dioxide. I expect they won't run much. As you mention in a post below they are "not interlocked with the HVAC".
If I am understanding correctly, 90.1 doesn't regulate these exhaust fans, so we model the motor's energy use but don't try to condition this whopping airflow in the energy model - is that correct? I'm still a little confused on this point.
Yes the addendum incorrectly labeled the system number. If you look in 90.1-2010 they use 9/10. These system technically can only be used in the spaces listed. In your case a system 9 would probably be accepted since it is conservative relative to a system 3.
An exhaust fan is process if it serves an unconditioned space or if it is separately controlled from the HVAC system serving that space.
If it is process then it gets modeled identically in both models. If you are conditioning the airflow then the fan is not process.
I see. So the energy model only includes a load for the motor power, but ignores the airflow - both because it is not part of the HVAC, and because safety controls will probably prevent it from running most of the time.
In the model the schedule you put the fan on will dictate its run time. The fan power and schedule is modeled identically.
I remember seeing from somewhere that if the exhaust fan is not interlocked with the HVAC, it should be considered a process load and modeled the same in proposed and baseline. Could someone point me the source of this or if this is applicable to EAp2. Thanks
I don't think there is anything to point to on this issue. A fan is process if it is not directly regulated by 90.1. So I can't point you to something that does not exist.
Fans serving unconditioned spaces are process. Fans associated with HVAC systems are not process. An exhaust fan within a conditioned space that is not interlocked with the HVAC is process too.
Thanks for the confirmation
I am a energy simulation engineer. Now I have a project which uses the district steam supplied by the local government as heat source.
I did the energy modeling based on the guideline "Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 – Design & Construction" option 1. When I set the energy rate in the modeling, I meet some problems.
From this guideline page 13 to 14, it seems that there is a formula to calculated the steam rate. My question is that does it forcibly to use this formula to calculate the energy rate? Can we use the local energy rate instead?
You are required to use the formula if the rate is not flat and you are applying DESv2 Option 1. You can use the local rate if it is flat under the DESv2 Option 1 or if you alternatively use Addendum ai from 90.1.
Would interstitial or interior blinds could contribute to load reductions and contribute to an increase in energy efficiency? What if the blinds are automated and these controls cannot be overridden by the occupants?
Manually operated blinds cannot be used to claim energy savings. They should not be modeled at all.
Automatic blinds are eligible for energy savings.
See Table G3.1-5 in Appendix G.
USGBC Addenda 100001062 updated the exterior lighting table for LEED v3 projects to the 90.1-2010 allowances. The addenda just says it updates credit SSc8 though. Should the new allowances be used for the energy model as well? My initial reaction is yes, but i can't find a similar addenda that says it applies to EAp2/EAc1.
Both methods are accepted for LEED 2009 projects in EAp2. You will show more saving with the old method. The new one would be considered conservative. 2010 better defined the allowance by lighting zone so it was adopted for SSc8 only.
Is there an accepted protocol for modeling in eQuest VRF systems with DOAS that does not require an exceptional calculation for seeking credit for EAc1? There are a variety of strategies that could all be considered to trigger an exceptional calculation as they are all indirect methods to manipulate eQuest/DOE2.2 to model something outside the normal inputs.
The VRF protocol we have used is from the Oregon Energy Trust. There are some that would likely be acceptable from manufacturers including Daiken and LG. A simple web search will find these.
Modeling VRF in eQUEST requires a work around as the software does not directly model this system. Any work around requires an exceptional calculation.
Exceptional calculations are required for, 1) claiming process energy savings, 2) when doing a work around, and 3) when violating a modeling protocol to show savings (like changing a schedule).
We are working on a LEED NC 2009 project with DES which the thermal plants consist except boilers and electric chillers also a cogenerator and an absorption chiller.
We are thinking to follow Option 2 of DES v2 guidance and have 2 questions as follows:
1. For the average efficiency calculation, should we deal with the CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. and absorption chiller separately and to model a virtual CHP and an absorption chiller in proposed case or to involve the CHP in the total heating system and the absorption chiller in the cooling system and apply the efficiencies separately to the air-cooled chiller and forced draft boiler in virtual DES model in proposed case?
2. In the DES v2 guidance Appendix E: Heating converted to cooling as part of the LEED project there was written:
‘‘Generally, district or campus systems that produce heating energy (steam or hot water, whether directly or as waste heat) serve heating end use applications in the connected buildings. Sometimes the heating energy supply is converted to chilled water using absorption chillers or other similar technologies in order to serve cooling loads instead. In this circumstance the equipment that converts heating to cooling may reside either within the DES itself (i.e., DES provides cooling to building) or within the connected buildings (i.e., DES provides heating to building; building converts heating to cooling).
When the equipment converting DES-supplied heat into cooling is part of the LEED project’s scope of work, then the DES guidance in this document must be modified for the EAp2/c1 energy modeling path. The modifications for this situation are as follows; guidance for all other LEED credits remains unchanged:’’
The question refers to the first sentence in the second paragraph: We treat the absorption chiller as upstream equipmentUpstream equipment consists of all heating or cooling systems, equipment, and controls that are associated with a district energy system but are not part of the project building's thermal connection or do not interface with the district energy system. It includes the central energy plant and all transmission and distribution equipment associated with transporting the thermal energy to the project building and site. outside the project’s boundary. Does that mean ‘‘part of the LEED project’s scope of work’’?
Thank you very much!
1. The absorption chiller should be included in the average efficiency calculation for the proposed virtual chilled water plant. The CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. is also included in the average efficiency calculations. For the CHP I would suggest that you also look over the guidance in the Reference Guide as a supplement to the DESv2. So they should not be dealt with separately.
2. If the equipment is part of a central plant and it not being installed as a part of the project pursuing LEED certification, then it is upstream equipmentUpstream equipment consists of all heating or cooling systems, equipment, and controls that are associated with a district energy system but are not part of the project building's thermal connection or do not interface with the district energy system. It includes the central energy plant and all transmission and distribution equipment associated with transporting the thermal energy to the project building and site.. If it is being installed as part of the project then it is probably not upstream equipment.
Regarding your reply to the first question, the input sources per unit cooling energy would be except electricity also gas(portion of CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. fuel input for chilled water producing). And for calculating the average efficiency for the proposed virtual chilled water plant, should the electricity input and the gas input be added as total energy consumption? Also for the proposed virtual model, the chiller could only have electricity as fuel source, how to apply the average efficiency to it?
Thank you for any help you can offer!
Yes the electric and gas input are added together to determine an overall consumption. The average efficiency would account for all of the fuel inputs. Model the electric chiller with a flat curve and apply the average rate converted to kWhA kilowatt-hour is a unit of work or energy, measured as 1 kilowatt (1,000 watts) of power expended for 1 hour. One kWh is equivalent to 3,412 Btu.. All fuels are factored into the rate determination which would be applied to the electric chiller in the model. The virtual plant with the average efficiency and rate should then be representative of the fuel mix and cost of the actual plant.
thank you marcus! very helpful tips to solve such problem.
We re currently working on an office building project of 10.000 square meters and within the building there is a data center as big as 150 square meters.
we are plannig to apply v2009 NC. we have made the energy modelling for the building and the calculations of the data center has decreased our energy points a great deal.
What i'd like to know is that, are the data centers within a new constaction building modeled with the same baseline values of the NC or not, since their energy consumptions are fairly high.
This is a process load and must be included in both models identically.
There is a spreadsheet you can use to show energy savings associated with a data center.
bit late to thank you but you are a great help thanks!'
I received a review comment requesting confirmation that my modeled fenestration U-valueU-value describes how well a building element conducts heat. It measures the rate of heat transfer through a building element over a given area, under standardized conditions. The greater the U-value, the less efficient the building element is as an insulator. The inverse of (1 divided by) the U-value is the R-value. accounts for framing. I'm having a difficult time contacting the window manufacturer. The data sheet states that "All performance data calculated using LBNL Window 5.2 software...." My question is: does this statement imply that the published U-value is indeed the framed assembly value?
The center of glass and the whole assembly U-values are commonly published. Usually the information can be found on their web site.
The window software they reference can be used to calculate both. It does not necessarily mean that it is an assembly U-value.
I am modeling a laboratory which has a small area of office space for LEED and wanted to check a couple of approaches:
1) The engineers have informed me that the lab has to be a once through system 100% outside air and therefore the baseline should be the same. I can't see anything in 90.1 which specifies this to be true or not however i do agree that it seems to be the correct approach.
2) They are also saying he baseline should use a constant volume exhaust as this is standard with bypass air (when the 100% outside air system loads arent high enough to meet the rate) to stack velocity. The proposed will undertake wind tunnel modeling to be able to reduce the exhaust makeup which is not standard practice and therefore can be done as an exceptional calculation.
3) Based on G3.1.1 (c) The baseline systems will be split for the lab (100% OA) and office (which will be VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. with re circulation).
1. The baseline is always according to Appendix G. The outside air should be identical to the proposed but the supply air is auto-sized by the simulation software according the G188.8.131.52. So if this results in a supply air which is greater than the outside air the baseline system will not be 100% OA.
2. It does sound like an exceptional calculation. Make sure to provide a detailed justification for the use of a constant volume baseline.
3. Sounds right.
I guess i am struggling to see what the proposed "outdoor air rate" is to match in the baseline if the system has to use 100% outside air. I think what you are saying is if the required rate for the lab is 6ACH then this should be the outside air rate in the baseline (despite the proposed having to use more than 6ACH of outside air so the outside air rates varies as it needs to be a once through system). You could say that the constant volume exhaust fo 27,250 dictates this in the baseline however i was modeling the makeup in the baseline for this as being bypass air to the exhaust as this is standard practice and not conditioning it.
If the exhaust is constant for example in this case 27,500 CFM per lab of makeup air. However if we get an exception following wind tunnel testing then it will varying based on the load
Also for labs, note:
1. I would expect you would need to incorporate G3.1.1 (d) in your baseline and proposed models, to reduce the amount of exhaust and makeup air by 50% during unoccupied periods. I would think you would run it this way first, then do a separate exceptional calculation for other nonstandard methods that reduce exhaust and makeup air.
2. Sometimes fume hood exhaust can be classified as process energy. If you can separate the fume hood exhaust energy (or maybe just the bypass air energy needed for fume hood exhaust) from the air conditioning energy, then it might be appropriate to treat it as process energy. The rule is that process energy should be the same in baseline as in proposed. However, if you have a nonstandard practice that you can document to reduce process energy, you can submit it for credit. This might be another way to look at part of what you are doing.
1. Victoria you are correct about the 6 ACHAir changes per hour: The number of times per hour a volume of air, equivalent to the volume of space, enters that space. being the baseline requirement. The baseline does not necessarily need to be a fully once through system. We agree that G3.1.1 (d) applies.
2. If the fume hood design is separate from the space conditioning system then we agree that it would be considered process.
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.
Addendum ch to 90.1-2007 helps with the 50% reduction during unoccupied periods as it scratches this. The proposed building has a set back to 4 ACHAir changes per hour: The number of times per hour a volume of air, equivalent to the volume of space, enters that space. which i'll mirror in the baseline (this is the lowest the AHJ will allow).
I think i will struggle to separate out the fume hood part of the system as it is all one combined exhaust system. So i may have to model as regulated energy...for 2010 this is correct i believe but for 2007 it is a grey area it seems. I think if i can pull out the additional fan energy from fume hood operation i could assign this as process.
The energy associated with the bypass air which is required if a constant volume fan is utilized can be calculated (difference in fan power in proposed between running constant with bypass air and running as required). I think this can then be added as process in both proposed and baseline and removed as an exceptional calculation in the proposed.
I don't see anyway this can be classed as regulated though and still take savings, as if regulated the flow rates should be the same.
I also have a similar question. If the baseline OA is set to be the same as proposed. This could be done at the design flow rate. But in annual simulation, the supply flow rate will vary based on the room load, thus it will cause the two system operate differently. One example: VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. with 100% OA for proposed. During cooling design for proposed, 1000 cfm is needed (100% OA). I set this value as the OA for cooling for baseline. However, at someday in summer, the proposed model needs only 500 cfm to meet the load, but the baseline is still using 1000 cfm because I forced it to use 1000 cfm.
The conservative approach would be to model the baseline at the minimum supply air flow in the proposed. Otherwise there would be a savings generated that would violate a modeling protocol. If you want to try an justify the extra savings you should approach it as an exceptional calculation.
Our project is a small office building in Europe, on site of a great industrial plant with the same owner. The office building aims to achieve LEED Gold certification, while the plant does not. There is an opportunity to receive free hot water as by-product of the manufacturing process from the plant, as well as cold water for cooling in the summer, that otherwise would not have been reused.
This way the office building uses only recovered waste heat for space-heating and cooling purposes. The system receives the heat at a heat exchanger and the secondary heat emitters are 4-pipe fan-coil units. There will not be any other heating or cooling devices for the project building, and it is the only building to use the waste heat and cool generated as by-product of the manufacturing process. Obviously, the heat source is out of the LEED boundary of the office project to be certified.
Do you think that it would be an acceptable solution to set the energy rate of the proposed model as zero (for heating and cooling) and model a district heating/cooling system while using a baseline system with an assumed usual energy rate and ASHRAE Appendix G baseline system configuration? Or can you suggest another way to take into account the ecological and economic benefits of the described system in the energy model and at this credit? Does anyone have experience with LEED documentation of such a system?
Any comments would be appreciated.
Marcus will give you the right answer, but I do not think you can say there is zero energy use. There must be some transfer means within the building. I do think you could define a cost of the fluids as zero in the as designed model. Not sure how that affects the baseline (Marcus?).
I was involved in similar project where we had a power plant adjacent to the project, and they agreed to allow the building to use the condenser water as a source. Now this water temperature was not of a temperature to use directly as heating or cooling, but was perfect for rejecting high performance heat pumps to! So the system was modeled as a ground source heat pumpA type of heat pump that uses the natural heat storage ability of the earth and/or the groundwater to heat and/or cool a building. The earth has the ability to absorb and store heat energy from the sun. To use that stored energy, heat is extracted from the earth through a liquid medium (groundwater or an anti-freeze solution) and is pumped to the heat pump or heat exchanger. There, the heat is used to heat the building. In the summer, the process is reversed and indoor heat is extracted from the building and transferred to the earth through the liquid. The geothermal heat pump is more efficient than an air-source heat pump. Also referred to as a "closed-loop" system. system, but instead of bores we had this condenser water. The system was still very efficient due to the much more constant temperature we could depend on. We did include a contact between the power plant and the agency for long term access to the condenser water.
So, you might want to have a letter if different companies, or a memo to the reviewers if the same company of where the water comes from and why it has a value of zero (ie is not created only for the building).
Technically the rules say that you would treat the incoming hot water and chilled water as purchased energy and the energy rates would be the same. If the rate is zero in the proposed, it is zero in the baseline.
It would not be acceptable to set the proposed rate at zero and the baseline at some usual rate using the standard Appendix G baseline system. Even if the rate is zero this is a purchased energy scenario and Appendix G (or the DESv2) would require that the "HVAC system" is purchased energy in both cases.
In order to claim savings I would suggest that you need to treat this situation as an exceptional calculation. You would need to provide justification for any baseline rate. IMO it should be based on the rates from the plant accounting for the system efficiencies (use the defaults in the DESv2 Option 1 if necessary). You will also need to provide justification relative to the waste heat/cool recovery. A detailed explanation will need to be provided about the source of the heat/cool to justify that it is truly waste heat/cool and not from a wasteful practice like once through cooling.
I've got the same situation on a current project.
Take a look at "Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 - Design and Construction" USGBC August 2010.
It gives you several options, but the one that looks most attractive to my project is this:
"Performance Option 2 (full accounting) – directly account for the efficiency of the district or campus energy source in the proposed case energy model and
compare it to a standard ASHRAE 90.1 baseline system in the baseline case.
This path is more complex but has no points cap. However, it does have a points floor: projects must achieve a certain minimum number of points in order to use this option."
"In Option 2, the energy model’s scope accounts for both downstream equipmentDownstream equipment consists of all heating or cooling systems, equipment, and controls located within the project building and site associated with transporting thermal energy into heated or cooled spaces. This includes the thermal connection or interface with the district energy system, secondary distribution systems in the building, and terminal units. and upstream equipmentUpstream equipment consists of all heating or cooling systems, equipment, and controls that are associated with a district energy system but are not part of the project building's thermal connection or do not interface with the district energy system. It includes the central energy plant and all transmission and distribution equipment associated with transporting the thermal energy to the project building and site.. The DES energy source is no longer modeled as cost-neutral purchased energy; rather, a virtual DES-equivalent plant for the Proposed case is constructed and compared to code-compliant on-site equipment for the Baseline case (Table 4). "
Table 4 goes on to indicate that the baseline system can be an on-site ASHRAE 90.1 heating plant, but the proposed system is a virtual on-site plant representing the upstream system (the district system).
So we'll have to account for pumping energy, but if the heat from the district system is really waste heat, and would be wasted if not used, and the remote process would run whether we use it or not, I think we could safely argue there isn't any fuel expended in producing the energy. In my case it is stack heat from a reciprocating generator powered by landfill gas, so the fuel really is free (and renewable). These generators run no matter whether we use the waste heat or not.
Be prepared to do a lot of explaining, and have this scrutinized by a reviewer. Might even want to ask the reviewers about it beforehand to get some guidance.
Hi, on a recent project we were requested to provide evidence that 5 buildings built within the last three years did not have carbon monoxide sensors installed in the basement car parks in order to claim any savings. We followed and referenced the methodology outlined in the Advanced Energy Modelling For LEED document produced by the USGBC.
Is it always a requirement to provide evidence as per above since the baseline building does not have any controls for basement parking fans? I was also under the impression that guidance referenced in the Advanced Energy Modelling Guide would be 'official' and no further justifications required if the method of calculation is clearly outlined.
There are several parts of the US where CO controlled ventilation in parking garages is required by code. There are also areas/situations where it is standard practice.
You are not justifying the method of calculation. You are justifying that CO sensors are not standard practice in your area.
I've gone through the threads and can't find a response for a question like this, there must be one, but we have a theater project with all of the speciality lighting associated with this use. It is an outdoor amphitheater, so the lighting use is very sporatic both programmatically and due to outdoor ambient lightingLighting in a space that provides for general wayfinding and visual comfort, in contrast to task lighting, which illuminates a defined area to facilitate specific visual work. during daytime hours. The theater consultant wants to use incandescent lighting as much as possible for color, etc. Is this type of lighting included in the energy model. Is it excluded in anyway, or partially excluded due to patterns of use and scheduling?
All energy use associated with the project is always included in the models. There are no exceptions.
Section 184.108.40.206 excludes theater lighting from the regulated requirements so you do not have to count it in the interior or exterior lighting power densities. It should be modeled as a separate process load identically in both models.
I wonder whether daylight sensing (lights are dimmed automatically according to daylight) can increase the points a project can obtain in this credit. Table G36.2 doesn’t mention such a system. Regards
Yes dimming systems are eligible assuming that the software can model the effect.
I am working on a project where the CRAC unit manufacturers have said they don't need to comply with the efficiency requirements of ASHRAE 90.1 for a data room and comms rooms air conditioning and they have quoted "The provisions of this standard do not apply to equipment and portions of building systems that use energy primarily to provide for industrial, manufacturing, or commercial processes" as the reason for this.
I believe that means that the actually air conditioning units themselves become process energy and as such should be the same in the proposed and baseline buildings?
The units themselves do not have a minimum efficiency as a mandatory provision but they are not considered process. Usually these units follow Section G3.1.1 Exception b and the baseline is modeled as a system 3 or 4.
ASHRAE 90.1-2010 establishes minimum efficiency for these units.
But if we are LEED v2009 and using ASHRAE 90.1-2007 (you mentioned they are covered under ASHRAE 90.1-2010) and the units are exempt then this then that would make them process as they aren't covered by ASHRAE 90.1-2007?
That does not make them process. If the lack of an efficiency minimum made something process then whole building space heating and cooling would be process for VRFs which do not have an efficiency minimum in 90.1-2007.
To Whom It May Concern:
I'm looking for guidance on how unit heaters, radiant panels and electric heaters that are in the proposed design are modeled in the baseline building. Keeping in mind that as this is a LEED Canada building and as per the LEED Canada 2009 Supplementary Energy Modeling Guide, if the proposed building has zones with no mechanical cooling, then there is also no cooling in the baseline building.
The building I'm modeling is an indoor soccer field house with associated support spaces (locker rooms, washrooms, spectator areas, offices, underground parkade). The building falls under System 7: 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. - Chiller - Boiler (Area > 150,000 sq. ft + NG boiler). As many areas receive transfer air from the field house (e.g. locker rooms), I have only included areas that are directly conditioned in the proposed building in the System 7 Baseline. Is this approach correct?
As per G.3.1.1, there is meant to be a System 7 modeled for each floor of the building. In the basement there is a parkade and a number of mechanical/storage rooms that have hydronic unit heaters. The Parkade has a MUA unit and exhaust fan system which falls under an exception as the fan only operates a few hours per day based on CO levels and is thus modeled as System 3. It doesn't make sense to me that the mechanical/storage rooms that only have unit heaters should be modeled as a System 7. So how should they be accounted for? Similary, the third floor contains the main mechanical room which is conditioned via unit heaters in the proposed design, so again it does not make sense to me to model as a System 7.
Furthermore, there are numerous spaces that are not directly conditioned via the primary air system and have local electric heaters (stairwells) and hydronic radiant panels (locker rooms with transfer air from field house). What would be the best approach to model these areas?
My initial guess would be to model the electric heaters in the Baseline the same as the Proposed (same capacities). Similarly, for the radiant panels. However as the unit heaters have a fan component, I'm not sure about the correct approach to model these in the baseline.
Any guidance is greatly appreciated.
The indirectly conditioned spaces must be included as part of your system 7.
Apply Addendum dn for heating only systems. You can model a system 9 or 10 from ASHRAE 90.1-2010 in the heating only spaces. Sounds like this would take care of your system 7 on a couple of the floors. There are limits to the space types which can apply this addendum, for example the locker rooms would not qualify.
Thank you for your reply and clear direction.
Out of curiosity, why should the locker rooms (they receive transfer air from the field house in the proposed design and contain hydronic radiant panels) be included in the baseline System 7? This would appear to penalize the baseline system as now the field house and the locker rooms receive direct airflow that will increase the baseline fan power.
Your clarification is greatly appreciated.
The configuration of the baseline systems rarely has anything to do with the proposed design (thermal zones being the primary exception). The locker rooms are conditioned space so appendix G defines the baseline system as a system 7, then it must be modeled as a system 7. If this increases the supply air cfm and therefore increases the baseline fan power your energy savings would increase.
Thanks for clarifying Marcus.
For a high rise project the client is considering investing in micro-turbines to generate electrical power on site from natural gas. The utility company will provide the fuel at a reduced cost to encourage the private micro-turbine use. With this reduced fuel cost (the utility's modified rate) the energy model saves a significant percent of the operating cost for the overall building energy use. This seems to be a win-win option for larger buildings, and can support LEED points in the EAc1 credit.
When you model them however, the gas rate needs to be identical in both models.
Understand. The modeling expects to see the same gas rate. On the other hand, the investment in the on-site equipment enables a reduced rate for the gas used for that purpose. It's unfortunate if the Owner's energy cost model can't benefit from that setup. Of course, they benefit in real expenses. Thanks.
Hi, I am starting work on a laboratory building and have been looking at the standards to see how they apply. The project will use both an ASHRAE 90.1 2007 and 2010 baseline building (one of LEED target and the other for separate project target). My questions are:
1) Bypass air to maintain exhaust stack minimum air flow requirements for plume. Can this be classed as process energy as it never goes into the space? I think it is
2) ASHRAE 90.1 2007 says the baseline should reduce exhaust and makeup air volume to 50% of design values during unoccupied periods – If this is not allowed by the AHJ would the requirement to have the full ACHAir changes per hour: The number of times per hour a volume of air, equivalent to the volume of space, enters that space. at all times (or as specified by AHJ) in the proposed supersede this statement for the baseline so the rates match.
1. I believe it's okay to classify fume hood exhaust (or the bypass air for fume hood exhaust) as process energy. However, it might be simpler to include all the fan energy in the HVAC energy. Process energy should normally be the same in the baseline and in the proposed, unless you have a well-documented special calculation showing process energy savings for a particular process.
2. I believe the way to model the makeup air would be to have both the baseline and the proposed reduce the makeup air to 50% during unoccupied periods. This is an ASHRAE 90.1-2007 energy model for LEED, not an energy model to accurately represent the energy use of the building. It's not really relevant that you won't actually be reducing the makeup air to 50% when unoccupied. You still have to model it that way to have the baseline and the proposed rates of ventilation match and to comply with ASHRAE 90.1-2007. (You may do something different for your ASHRAE 90.1-2010 model, depending on the purpose of that model.)
I have a question, we have received a comment from a LEED reviewer requesting for the following information:
"Table 1.4 of the template appears to indicate that all the assembly U-valueU-value describes how well a building element conducts heat. It measures the rate of heat transfer through a building element over a given area, under standardized conditions. The greater the U-value, the less efficient the building element is as an insulator. The inverse of (1 divided by) the U-value is the R-value. for the exterior walls in the Proposed model may not account for the thermal breaks due to the steel-framing portion of the construction assembly. Each construction assembly U-value is not a direct inverse of the insulation R-value for that construction assembly. The R-value of the insulation located between the steel framing must be de-rated when determining the assembly U-value for the exterior wall assembly to account for the reduced thermal resistance of the metal framing components. Revise the Proposed model, as needed, so that all components of the exterior wall construction assembly are accounted for when calculating the assembly U-value for assembly type in the actual design. In addition, update Table 1.4 reflecting the changes. Refer to Table A3.3 in ASHRAE Standard 90.1-2004 for additional guidance regarding how to de-rate the R-value for insulation located between steel framing assemblies."
We have the following wall composition in the project (Based on arch dwgs): 5/8" Gypsum Board + Metal Stud every 24 in O.C. + 8in CMU Block with injected R8 + 5/8" Hardie Board
So we are updating the assembly based on table A3.1A (Ashrae 90.1-2004 Appendix A) with a U-0.125 (= R8 Assembly) however, since this table in my understanding is only accounting for the concrete block, the insulation and the metal framing, I have added the 5/8” gypsum board (layer 1) and the 5/8” hardie board (layer 7) to the modeled assembly as well. Has anybody had a similar comment? How did you addressed it? Thanks.
The appendix a tables already include assumptions about the entire assembly. Make sure to read the beginning of A3.
We are working on a LEED NC 2009 project in Germany with DES which the thermal plants consist 5 boilers and a cogenerator.
We are thinking to follow the Scandinavian DES protocol to replace Option 2 in the DES v2 guidance. According to 4.1-Equation 1:
PEFdh = ∑Ef,hob(i)*PEFhob(i)+ ∑αh,i*Ef,chpCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source.(i)*PEFchp(i) / ∑Qdel,j
The energy inputs in fuel and the delivered heating energy are requested to calculate the total primary energy factor.
The question is, are the energy inputs in fuel (Ef,hob(i), Ef,chp(i)) and the delivered heating energy (∑Qdel,j) the total annual amount or can I take the specific value in kW as planned. So far the DES does not yet exist so we don’t have the annual amounts.
If the total annual amounts shall be used here, then what is the difference between this alternative and the Option 2 in the DES v2, in which the annual energy consumption and the generated energy are also requested to calculate the average heating efficiency.
Any advice is appreciated. Thank you in advance.
The Green Engineer, LLP
Documentation of EAc1 is completed through EAp2. The same energy-efficiency measures contribute to both credits, with additional measures needed to earn points for EAc1.
Limits on interior and exterior lighting can help in reducing energy loads.
Use daylight sensors to control electrical lighting, reducing electricity use from natural daylight, as well as cooling loads.
Excessive glazing in the name of providing views can reduce energy efficiency. This does not have to be the case, however.
Building systems contributing to energy efficiency are to be commissioned.
Earning this credit helps to realize the operational benefits of energy-efficient design.
Projects using energy modeling for EAc1 can earn points from onsite renewables, while also earning points under EAc2.
The computer model developed for EAc1: Option 1 is calibrated and refined under M&V.
The quantity of green power purchases is based on the energy model created for EAc1, if one is created. Green power does not help earn points under EAc1, however.
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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