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.
We are modeling a building in EnergyPro that is heating only, with radiant heating panels and ventilation thru DOAS.
We received a LEED review comment stating: "If the heating output capacity is greater than or equal to 10 BtuA unit of energy consumed by or delivered to a building. A Btu is an acronym for British thermal unit and is defined as the amount of energy required to increase the temperature of 1 pound of water by 1 degree Fahrenheit, at normal atmospheric pressure. Energy consumption is expressed in Btu to allow for consumption comparisons among fuels that are measured in different units./hour/square foot then the space is considered conditioned so cooling should be included in the Baseline and Proposed Case models. The cooling should be modeled using the Baseline cooling system type (System Type 1) in both the Baseline and Proposed Case model using identical cooling capacity ratios and efficiencies in the Baseline and Proposed Case."
EnergyPro automatically models cooling into the baseline model, however, we did not model cooling into the proposed model. How are we supposed to model cooling into the proposed model, when it does not exist it real life?
You have two options.
1. Model an identical to the baseline cooling system in both and then enter the cooling set point at a level that will ensure that it never operates. This work around is allowed by the modeling protocol.
2. Tell the reviewer that you are aware of #1 and feel it is a waste of time to include non-existent cooling systems, so you did not bother to include them in either model and remove the cooling from the baseline.
The second one has been accepted many times before. You most certainly should not be modeling a cooling system in the baseline and none in the proposed. This will likely overstate the savings.
I believe you can cite 90.1 Addendum dn to model heating only system (9 or 10) for spaces that does not have cooling system in design.
You can only model a system 9 or 10 in certain, very limited space types. This usually will not include all the space types found in most buildings.
We recently completed the Final Design Review and realized we exceeded the 50% threshold for Energy performance for EAc1. Can I still pursue the exemplary credit by updating the form and resubmit during the Prelim. Construction Review?
The reviewer should have pointed this out to you.
Did anyone see the that USGBC has launched a set of proposals to increase the energy minimums for LEED v2009, which is open for project registration until October 31, 2016. Please visit: http://www.usgbc.org/articles/public-comment-period-open-until-1113-leed... to see the announcement.
I like the proposal to increase to the minimum energy performance thresholds for LEED 2009, however I wish that the new proposal would be to simply adopt the energy requirements and standards in LEED v4 and just be done with it. ASHRAE 90.1-2010 is the latest and greatest building energy code (standard) in most states. By changing the existing LEED v2009 (ASHRAE 90.1-2007) to v4's 90.1-2010, it would actually save project teams time in having to run two separate energy models because the building would not have to be compared against both standards. AND it would meet the intent of the proposal, which is to ensure that LEED v2009 keeps pace with the latest state energy code adoption.
Yes, I am aware that project teams may substitute the requirements from LEED v4 for certain prerequisites and credits, but the fact that many states have already adopted, or will soon be adopting 90.1-2010, it's time to cut the apron strings and raise the sustainability bar...to code. Simply allowing projects to earn additional points in order to achieve certification is "exemplary performanceIn LEED, certain credits have established thresholds beyond basic credit achievement. Meeting these thresholds can earn additional points through Innovation in Design (ID) or Innovation in Operations (IO) points. As a general rule of thumb, ID credits for exemplary performance are awarded for doubling the credit requirements and/or achieving the next incremental percentage threshold. However, this rule varies on a case by case basis, so check the credit requirements." and projects can earn these Innovation points. Specific new point thresholds that represent the percent increases in energy efficiency has somehow got to align with the point thresholds as defined in v4.
Personally I think this is just confusing. When trying to compare a LEED v2009 building to a LEED v2009 building and discussing points earned, it gets messy and confusing. Just go with implementing the LEED v4 requirement of ASHRAE 90.1-2010 and give people a 60 day notice. That should satisfy most project teams.
By transitioning to code (90.1-2010), it would be a smooth transition for project teams regarding LEED v4, and more importantly, ensure that LEED-certified projects continue to exemplify LEADERSHIP in energy performance. I certainly hope that any version of LEED would always reference the latest building code/standard and the not the previous version(s).
I tried to post a thread on this last week, but was running into website errors. I posted a comment in the credit library, which I think is public (although it kept trying to reset the toggle to private), which I'll repost here for possible discussion.
The prescriptive options should remain in place. These (especially the Core Performance Guide) are painfully underrecognized by point allocation, yet deliver buildings that significantly outperform an ASHRAE 90.1-2007 baseline by 16-26% depending on climate (savings determined by NBI analysis of 20-30% improvement of the Core Performance Guide beyond 90.1-2004, and discounted to reflect 3.9% average energy cost difference between the 2004 and 2007 versions of 90.1). I suggest explicitly allowing both option 2 and option 3 as prerequisite-satisfying options, but stripping them of points to help encourage teams to use the new (now higher) thresholds of Option 1.
I don't think prescriptive options are widely used (maybe in Volume/Prototype projects), although this change literally forces an energy model, which isn't always a good investment for small projects as long as there is a credible prescriptive path.
Also, while smaller steps between the "big step" (represented by mandatory v4 as of 11/1/2016) can be of value, I'm more concerned that raising the bar on EAc1 allows for further delay for the switch over to v4.
It is my hope that USGBC reaffirms their plan to halt new LEED 2009 projects after next October, and that any interim changes won't further set back v4.
I am for any raising of the bar so I support the move. Unfortunately there are still 34 states with 90.1-2007 or worse as the minimum. LEED ceased being on the leading edge of this issue several years ago. There are only two states who automatically adopt the latest version of 90.1 so all the rest lag behind to a certain extent.
This lag in 90.1 adoption is directly related to the lag in requiring LEED v4. They are obviously trying to fill a gap for the next year (hopefully no more). Looks like 90.1-2010 will have to wait until next October to take effect in LEED. Shortly after that 90.1-2016 will be out and because of the huge lag in v4 it will be basically out of date when it starts. This lag in v4 will adversely affect LEED for years to come unless they adopt a continuous improvement development schedule that makes sense. Annual updates to LEED should occur and perhaps include automatic adoption of new standards as they come out.
Regarding baseline changes - there was a proposal to create a fixed baseline using 90.,1-2004 Appendix G. Not sure where that stands but certainly some complications as Appendix G evolves and fixes issues.
Regarding prescriptive paths - I don't think this is much of an issue. In theory they are a good idea, especially for smaller projects. In practice almost no one uses them for LEED. I think the utilization rate is well under 1% of project submitted use them.
Theresa - if you are doing a v3 project but using 90.1-2010 as your code, there is now an ACP with a point table for savings against 2010. We run into this a lot, since 90.1-2010 is our base code in Massachusetts. It saves having to construct two baselines.
I am in favor of the proposed upgrade as a stepping stone to help fill the current gap in minimum energy performance between LEED 2009 and LEED v4. However, this will cause some buildings not to be able to meet LEED; especially existing buildings being renovated or having additions.
We were recently involved with analyzing and existing building that with additions would be 200,00sf. The additions total 25,000 sf and renovation 13,800. Total additions and renovations are slightly less than 20% of the total.
based on the best reasonable case, given the constraints of the existing building and with a fairly reasonable budget, it appears the renovated and addition areas would only be able to save 12-15% over the referenced LEED 2009 ASHRAE Std 90.1-2007 baseline. Thus it would not qualify under the proposed new requirement.
If the project would have a chance to meet the proposed new requirement we would have to change out the existing curtain wall and make other improvements to the building envelope that would cause a major increase in the budget - which is not able to be expanded. This project would then not be able to be LEED certified at any level because it could not meet the newly proposed energy standard.
But maybe that is OK. Every building should not be LEED, especially if they are not able to meet accepted minimum standards,. The down side is that when the LEED process is abandoned and the mandate becomes "design to LEED" or "design to best practices" the projects rarely come close to meeting the other LEED thresholds.
I also support this change, and wish it had been sooner and deeper. As a transition to v4, this could have made the move much more of a transition than a change. Having some lag to adoption to code is not all bad, but typically it should only be the 3 year cycle, not even farther. With some states considering rolling back energy codes to "create jobs", it is going to be harder in many areas to get code to catch up in any meaningful manner.
Project is LEED-NC v2009 project in which a building contains a DES that serves the project building as well as a larger adjacent building. We are using DES Option 2 (with a point floor of 6 points or 22% energy cost savings). Currently our model shows that we have earned 21.45% and we have looked at everything multiple times to get to 22% to no avail. Then we read the following note about the points floor. Does the exception apply to our project, since the building housing the DES is in fact our LEED project building, even though the DES also serves another building? See the excerpt below:
"points floor means this is the minimum number of points that can be earned in this scenario; projects seeking fewer points must use Option 1. (Exception: this points floor does not apply when the building housing the thermal energy plant is itself the LEED project building.)"
I think the exception applies when you are talking about a building seeking certification that houses only the central plant. Central plant buildings would commonly be built in a larger campus scenario.
I am working on a project that consists of 2 buildings on one site that I plan on certifying using the Group Certification option discussed in the LEED Campus Guidance document.
In attempting EAc1 Option 1, I would need to model both buildings as a single building (not quite sure how to do that) or am I to produce 2 separate models and add them together? Seems rather cumbersome...
You can do it either way under 2009.
In v4 you would have to model them separately because each building needs to meet the minimum individually.
I'm not really sure how the envelope should be input in baseline vs. proposed. Here is the reviewer comment "The LEED Summary report indicates that a single wall construction was modeled in both the Proposed and Baseline cases. However, this is unexpected in renovation projects. Additionally, it is unclear what constructions are renovated, which are existing non renovated constructions, and which are new constructions. Further, it is unclear whether the existing envelope conditions prior to retrofit were modeled consistent with the requirements of ASHRAE 90.1-2007 Table G3.1.5(Baseline)(f). For all envelope assemblies located in spaces that were conditioned prior to retrofit, model the Baseline Case envelope U-factors, SHGCs, and F-factors using the existing conditions prior to retrofit. Additionally, clearly identify all existing renovated, existing non-renovated, and new constructions, revise the Proposed building appropriately, provide the revised LEED Summary, Library Members, and Space Entered Values reports from TRACE, and update the form and tables accordingly. Ensure that separate reports are provided for the existing renovation versus new construction envelope assemblies in Supplemental Table 1.4 for both the Baseline and Proposed Case."
Sounds like you have a project that includes both new and existing envelopes.
New - Baseline according to the appropriate Table 5.5-X depending on 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.. Proposed is as designed including the effect of framing and thermal bridging.
Existing - Baseline is existing condition. Proposed as designed.
So there should be at least two different wall types for both the baseline and the proposed. If you have walls with different thermal performance you may have more that two in the proposed.
but what if the wall if one of those components that are being reused, shouldn't it be the same in both baseline and proposed, since we are not making any changes to it?
Yes. That would be covered by my explanation of the existing walls. If you make no changes to the existing wall then that is both the existing condition and the as designed condition.
We are doing a factory project in pakistan, which have a 1200 kw process machinery load, after energy modeling without process load we are saving 55 % from baseline but after adding process load same in both baseline and design case our saving goes down to 35% now my question are that
1) What we should do to get 50% saving because our building envelope and HVAC system is already high efficient.
2) How to deal with process load.
3) What about solar system that should be 13 % of your electric bill, including process load consumption or without it..?
Your model must include all energy use in and associated with the project.
1. In a high process load building you usually need to address the process itself to get high levels of savings.
2. Model it as accurately as you can. To claim any energy savings you must establish a baseline and justify it relative to any energy savings strategies the process will employ.
3. The process is included in all calculations like this.
I just wanted to verify that "Two (2) points mandatory for all LEED for New Construction projects registered after June 26, 2007" rule is no longer in effect.
Referring to this:
I've had a few people mention this to me, but I thought that LEED v2009 USGBC folded this level of performance into EAp2, so the 2-point minimum in EAc1 does not apply anymore.
Would just like to confirm.
The 2 point minimum only applied to LEED v2.2 projects.
This is what I thought.
We recently received a final design review where our percent energy cost savings have been corrected by the reviewer to show 31.95%. This project is an existing building renovation, so the associated points are currently shown as 12. We are curious if in others experience this 31.95% may be rounded to 32% energy cost savings, which would yield 13 EAc1 points instead of the current 12. Any past experience or knowledge of the rounding in this calculation would be greatly appreciated. Thanks!
LEED online should be able to calculate the savings rounded to .1%. However, its very likely the reviews will drop your savings so you end up being one threshold lower. I suggest you tweak some schedules (such as lighting) to get more savings so you have some buffers for review comments
No rounding up is allowed.
I would suggest that tweaking schedules for the sole purpose of increasing your savings is not an ethical practice. In the grand scheme of things certainly a minor ethical violation but IMO it a violation of the ethical standards that modelers should uphold. I certainly understand that the "tweak" is well within the potential margin of error and that modeling is generally not conducted with a high degree of precision but you have to draw ethical boundaries somewhere.
For the rounding I remembered it wrong, LEED will calculate up to 0.01% so for your case you cant round it. If you have 31.995% then LEED will calculate it as 40.00%
For the tweak, I would say the schedule itself is simply an estimation. So I believe this is not even close to a ethical problem. It is a ethical problem if you know the exact schedule but choose to use a different one, such as ventilation schedule. For lighting schedule, if you can estimate 50 hours/week, you can also estimate 55 hours/week as long as they can represent how the building operates.
There is a similar questions I asked few months back here, it has more comments.
You caught me inside my own ethical dilemma. Apparently I did suggest a tweak for the purpose of increasing the savings. I think it is a question of what is allowed versus what is right. The tweak is certainly allowed but is it ethical? This could certainly vary depending on the specific tweak and the source of the information used to create the modeling input.
I think we should always model the input parameters as accurately as we can with the information we have. If the lighting is projected by the owner to operate 50 hours a week, then that is what we should model. How did you obtain the information used to produce the lighting schedule? If the source was known I consider it unethical to add 5 hours for the sole purpose of increasing your savings. For me this is clearly unethical since you are changing a modeling input you know is less than accurate in order to garner greater savings. Just because we can, does not mean we should.
Perhaps the issue here is more related to the accuracy and source of the input data used in the models. We try to be as accurate as possible and obtain the input data with significant input from the owner and design team. In our process there would be no ambiguity about whether the lighting schedule would be for 50 or 55 hours.
There certainly may be other tweaks one could consider making that would not present the same sort of ethical dilemma.
I agree with you that if we know the exact schedule we shouldn't change it as I also mentioned it in my previous post. But if the schedules are based on estimation, IMO they can be changed as long as it represent the building operation. The owners usually give the building operation schedule, but there is always difference between building operation schedule and lighting schedule since there are always people like us who work overtimes and thus keep the light on. For residential project, the schedule can vary even more since lighting are controlled by occupants. And I use lighting simply because it is first thing came into my mind, there definitely are other things that can be better examples
Thank you both for clarifying. The rounding information is very helpful to know for the future. As for my current situation, it seems the only option for attempting to get the point back is to appeal the review (since it is the final design review) where our energy savings have been modified by the reviewer. Is my understanding of this process correct?
Sorry to hijack your post for our discussion of ethics.
Unless you can point to an error made by the reviewer you will need to appeal. If you feel the reviewer was in error you can submit an inquiry via the GBCI Contact Us on their web site.
No worries, Marcus. It seems good to have these ethics conversations as a community in order to hear all the different sides. Otherwise, we end up sort of operating on our own islands. Thanks for clarifying the options.
Joseph said this was the final design review, not the final construction review. Couldn't Joseph go back through the model to make sure he didn't miss any potential small savings by not choosing to model it (something like shading, for example) and resubmit a revised energy model with the construction review if he finds something that pushes the savings up above 32%? Or if that's not acceptable, I suppose there is a remote possibility that something changed in the positive direction between design and construction. Would that be a reason to resubmit the energy credit during construction?
You are not supposed to submit the model for a third review unless something changed in construction and you are only allowed to make those changes. If that is the case then you can submit for a third review but you should not be changing anything else in the model unless you note the change and indicate that it was originally modeled in error. You can't submit the model for a third review to correct any modeling errors or to model an omission.
But you could go back to the project team, suggest some additional energy efficiency measures, implement those measures, and resubmit the model for the improved building.
My inquiry is based upon reducing the energy consumption of a chilled water system which is being used in a manufacturing facility. The chilled water system is specifically used for the manufacturing process. The type of mechanical equipment used to chill the water is an air-cooled refrigerant chiller.
The thought is to add dry coolers to the chilled water system in order to take advantage of the local climate. The chilled water temperature needs to be maintained at approximately 45 deg. F (setpoint). The operation of the drycoolers would be sized for the full load of the mechanical chiller. Either the mechanical chiller will be on and the drycoolers off and vice versa.
1) Does an exceptional calculation apply for this case in order to show an energy savings for the process loads between the baseline and the proposed buildings, therefore improving the efficiency of the chilled water system?
2) If No, what is meant by "improvements to refrigeration equipment efficiency" mean as stated in the LEED v2009 Reference Guide?
3) If Yes, do both systems (chiller and dry cooler) require btuA unit of energy consumed by or delivered to a building. A Btu is an acronym for British thermal unit and is defined as the amount of energy required to increase the temperature of 1 pound of water by 1 degree Fahrenheit, at normal atmospheric pressure. Energy consumption is expressed in Btu to allow for consumption comparisons among fuels that are measured in different units./ kW metering in order to prove the "specific energy cost savings as stated in the LEED v2009 Reference Guide?
1. Yes you need to do an exceptional calculation for any process load savings claimed. The baseline should be justified as standard industry practice in this location for a new plant.
3. No metering is required for this credit.
Thank-you for the reply. Another issue has come up regarding the energy savings applied with the dry-coolers. It turns out that the total process energy is a much higher quantity and dilutes the total energy saved percentage. With the energy saving strategies implemented into the building itself, the percentage of improvement compared to the baseline is very minimal. Is there a different way to portray energy savings for the building separately from the process side in order to gain points for the other strategies implemented into the building?
No. All energy use within and associated with the project must be included.
There is an alternative compliance path for meeting the prerequisite only but it does not help earn additional points. The only way to get more point is to find more process energy savings.
I've been trying to understand how does LEED treat kitchen exhaust hoods with make up unit(heating only) in the energy model. Is it process or non-process? The LEED reference guide 2009 v3, states its regulated (non-process). I have a building that is 90.1-2007 system 5. Do I have to model kitchen hood exhaust and make-up air unit as process or non process?
It is process assuming that the unit does not also provide space conditioning for the larger kitchen. If it provides space conditioning to the larger kitchen then it is not process.
Hi I’m working on a High-rise residential LEED energy modeling project now. I have a question regarding the lighting. I’m using Energypro, and found out the lighting saving is zero from the Title-24 LEED calculation no matter what the design input is. Does that mean we cannot count on lighting savings for residential project?
2nd question: the first floor of this project is retail area. MEP wise, it’s for future use. So there is no design on that area. But this is a LEED NC project and the retail area is included in the architectural design, and will be included in the LEED scope. For this kind of situation, how should I model it?
3rd question: can I treat the underground garage lighting as exterior lighting?
Hi, I’m working on a High-rise residential LEED energy modeling project now. I have a question regarding the lighting. I’m using Energypro, and found out the lighting saving is zero from the calculation no matter what the design input is. Does that mean we cannot count on lighting savings for high-rise residential project?
3rd question: Can I treat the underground parking garage lighting as exterior lighting?
Any advice is appreciated. Thanks.
1. Not sure why you can't show lighting savings in EnergyPro. To claim residential lighting savings follow the guidance in this document - http://www.energystar.gov/ia/partners/bldrs_lenders_raters/downloads/mfh...
2. The proposed HVAC is modeled identical to the baseline system.
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.
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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