CS-2009 EAc2: On-site Renewable Energy

  • CS EAc2 Type3 Onsite Renewables Diagram

  • Lower cost strategies come first

    Capturing useful energy from natural energy flows like sunshine, wind, moving water is a great concept. The technologies to capture this energy aren’t cheap, however, nor do they work equally well in all locations. Typically, it’s hard to generate a significant fraction of total electricity we use onsite.

    Before investing a lot of time and energy into this credit, focus on energy efficiency and passive energy collection such as daylighting, natural ventilation, passive solar heating before investing in renewable energy systems. This work will probably pay off faster than renewable energy, and if you do invest in renewable energy, you’ll have a lighter load for it to carry.

    What types of systems count

    All electricity generated and heat used on site is counted towards the credit. Electricity and heat generated onsite but sold to the grid at a premium is not eligible. (See table.)

    Type of system and eligibility for EAc2 points

    LEED allows you to take credit for technologies that generate electricity and heat from sun, wind, water flows, and waste biomass. It also allows certain thermal technologies, such as solar hot water, concentrating solar collectors, biomass, and geothermal (extraction of heat from within the Earth, not ground-source heat pumps).

    Of these, solar hot water systems are typically the most cost-effective. Small wind turbines have been found to not make sense on or near most buildings in urban areas because they need strong, steady winds, while the air around buildings is very turbulent. (See Resources for more.)

    Centerbrook ArchitectsCenterbrook Architects in Centerbrook, Connecticut, supplies about 20% of its power needs with onsite photovoltaic power, including this 26.4 kW array. The Falls River, in the background, powers a small hydroelectric turbine supplying another 10% of the firm’s power. Both sources contribute to this LEED credit. However, many small installations like this find it financially important to sell RECs from the renewables, which would make the power ineligible for the credit. Photo – Centerbrook Architects and Planners, LLC Depending on the features and location of your site and the expertise available, the technologies you can use are:

    • Solar photovoltaics (PV)
    • Wind turbines
    • Small hydroelectric generation
    • Certain types of biomass and biofuels—untreated wood waste, agricultural waste and animal waste
    • Landfill gas captured as fuel
    • Fuel cells if hydrogen is produced onsite without using fossil fuels
    • Solar-concentrated power for steam turbines
    • Solar-thermal hot water
    • Activity-generated electricity.

    Follow the money

    The federal government and many states have a variety of incentive programs to encourage the use of renewable energy. These incentives can offset up to half of the costs in making systems cost-effective. Many states also have laws that provide for net-metering so that you can feed the excess electricity into the grid and get paid by the utility for that electricity. Some utilities will offer you above-market rates for feeding green electricity into their grid, but if you do that you’re selling the power’s green attributes as RECs, so you’re not allowed to use that energy to earn this credit.

    Wind turbines on parapetThe Adventure Aquarium in Camden, New Jersey, features eight 400-watt and four 1000-watt parapet-mounted AeroVironment turbines. Photo – Jeff Titcomb

    Start by analyzing the site’s resources

    The natural resources harvested by renewable energy technologies are site- and climate-specific. You can use both online databases and direct investigation of the site to figure out which technologies might be feasible. There are many factors to consider, so it’s wise to bring in an experienced consultant and/or technology vendors as early as possible in the design process to help with feasibility studies.

    Double dip with energy credits

    You can double-dip with onsite renewable energy. In addition to earning this credit, renewable energy helps to offset total annual building energy use, contributing to EAp2 and EAc1, if using Option 1: Whole Building Energy Simulation.

  • FAQs for EAc2

    We have a PV array installed on our campus, under the same ownership, but not on the building or within the LEED project boundary. Can we count that toward EAc2?

    Yes. Provide a letter from the owner allocating some or all of the solar power to this project. Make sure that the solar power allocated to the project is not already allocated to another LEED project, and won't be in the future. Also, be sure that the owner retains ownership of the power and the RECs being generated.

    Because of how our onsite PV system was financed through the utility, the project is selling the RECs associated with its solar energy production, even though we own the PV array and its power. Is there any way we can earn EAc2?

    Yes, as discussed in the LEED Reference Guide and reinforced by LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org. #10161 made on 04/01/2012, you can buy RECs for your project to make up for RECs for 100% of what you want to claim for EAc2. You may not apply these REC purchases toward EAc6: Green Power.

    Can I pursue this credit if I am using one of the prescriptive compliance paths for EAp2/EAc1?

    Yes. You can use the 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. data as explained in the LEED Reference Guide or use the actual energy data from the facility.

    Can I really double-count onsite renewable energy in both EAc2 and EAc1?

    Yes. You could theoretically offset an inefficient building with a lot of renewables. As a matter of best practice, and of cost-effectiveness, you should start with efficiency measures, however.

    Our PV system is being installed after the building is occupied. Is that okay?

    Yes, but don't push the timeframe too far. The credit form asks the owner to verify its installation. It would be a good idea to provide a purchase order or contract and installation schedule as documentation.

    Our project will have a PV system onsite, but it will be installed, operated, and owned by a separate entity that is paying for the system through a premium price per kWh paid by the utility, per state regulations. Is there any way to count this toward the project, in EAc2 or EAc1?

    Probably not. LEEDuser's experts have not seen this attempted, even though it comes up from time to time. You would need to make your case via a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide or LEED Interpretation. The only LEED benefit you are likely to get here is through SSc7.1—shading your hardscapeHardscape consists of the inanimate elements of the building landscaping. Examples include pavement, roadways, stone walls, concrete paths and sidewalks, and concrete, brick, and tile patios. with PV panels.

    A biofuel-based cogenerator is being used to produce both electricity and heat (CHP). Can I consider all the energy produced, or just the electricity?

    Yes, all the energy would qualify. Check the CHP guidance in the district energy systems modeling protocol.

    Can a backup generator qualify, if it runs on biofuels?

    If it is only used for backup—no. It might be able to contribute if it is run regularly run, for peak shaving, for example.

Legend

  • Best Practices
  • Gotcha
  • Action Steps
  • Cost Tip

Pre-Design

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  • Analyze the site to find out what renewable energy resources it offers. See Resources for help on this. 

  • Identify relevant technology options for the available resources. 

  • Incentives of various kinds often mean the difference between pursuing this credit and not. Identify tax rebates, subsidies, cost-sharing, long-term leasing, net metering opportunities, and other incentives available from local, regional and national authorities as well as utilities. See Resources for help on this. 

  • Consider the location, available space, structural and maintenance requirements of possible renewable technologies, bringing your focus to the most applicable. 

  • Stillwell train stationThe Stillwell Avenue Train Station of the New York Metro Transit Authority used RWE/Schott PV glazing for the 76,000 square-foot curved roof; these custom ASI THRU panels provide 20 to 25% light transmission and are expected to produce 250,000 kWh per year. Photo – Schott North AmericaBuilding-integrated installations can work even if space is tight on the site. Consider wall-mounted PV panels, vertical terrace-mounted solar thermal, or PV integrated into the glazing, for example. These technologies often sacrifice some efficiency for convenient placement. 

  • Start by reducing the building’s energy load. The smaller the load, the less renewable energy you have to generate to meet the credit thresholds, which saves money and might expand the options you can use. For example, a 100-MMBtu/year building needs to produce 1 MMBtu/yr to reach the 1% credit threshold, while an 80-MMBtu/year building needs only 0.8 MMBtu/year. 

  • Conduct a preliminary cost-benefit analysis to determine the first cost and life cycle payback. Most teams use LEED point thresholds as a way to frame the analysis. For example, what is the cost and the payback of meeting the 1% threshold?

  • Contact an experienced renewable energy provider who can provide generation capacity for solar, wind or hydro systems installed onsite in a pre-feasibility study and identify potential obstacles. It is easiest to locate the providers through the trade organizations or manufacturers. For example, a wind turbine manufacturer should be able to provide names of qualified vendors who can visit the site and provide a written feasibility report based on the site specific wind speed, hourly generation capacity, and major obstacles like neighboring buildings. If a systems provider is not available, get names of electrical engineering firms who can do the analysis. Look up NREL and trade organizations to obtain the directory listed in Resources.  

  • Cost is a huge issue for renewable energy installations. In initial assessments from the renewable energy provider, look for generation capacity estimates and a cost-benefit analysis for long-term operations. Some providers may offer an initial assessment at low or no cost. 

  • If your project is located in the U.S., consult wind and solar maps developed by the Department of Energy (see Resources). 

  • The owner and team establish goals for onsite renewable energy based on the initial assessment. Include goals in the Owner’s Project Requirements developed during early design for Fundamental (EAp1) and Enhanced (EAc3) commissioning.

  • Find out if net-metering is available in your area. Net metering allows you to feed power that your system generates into the electrical grid and get paid for that power. This allows you to use the grid as a battery, which saves the cost and hassle of installing and maintaining a battery system. (Without batteries, however, you won’t have back-up power to use in a power failure or idle periods). Typical PV, wind and other on site systems generate DC current which has to be stored for future use and converted to AC current for onsite application. This is one of the biggest barriers to generating onsite electricity as battery storage is expensive, inefficient and hazardous. Now, many utilities allow excess electricity to be supplied into the grid, thus eliminating the need of an onsite battery. Confirm whether if your project site is connected to a utility or grid-tied where net metering is available. 

  • Onsite generation can reduce peak utility loads, reducing utility costs and need for electricity generation capacity. Utilities often encourage onsite generation and support it with subsidies and incentives.

  • Account for inflation and increases in utility costs over the next few years to obtain a realistic cost-benefit analysis, as ROI and payback are highly dependent on utility charges for conventional energy. Look up the costs of electricity in your state and projected price for the calculations. Also obtain the actual inflation rate current at the time of the ROI analysis. Retail residential electricity prices increased an estimated 8% during the first quarter of 2009 compared to the first quarter of 2008 according to a June 2009 report by the U.S. Energy Information Administration. (See Resources.) 

  • Look for partnerships with local utilities and other groups who can purchase excess electricity. Some utilities are looking to encourage more existing facilities to generate electricity from renewable sources to increase their renewable portfolio. Also, they may be short on space to install their own system or need an experimental site for net metering. 

  • Allocate space on or around the building for solar arrays or wind turbines, and include this early in site plans and budget considerations. 

  • Roof mounted or on-site generation technology is considered a mechanical system so the area it takes up is excluded from calculations for the heat island reduction credits, SSc7.1 and SSc7.2.

  • Consider standalone systems that are easier to install. Electrical vehicle charging stations can be easily hooked up to PV panels, for example. Standalone solar-powered site lighting (in which a small PV panel is integrated into each fixture) can be solar powered throughout the year and reduces the infrastructure requirements of wiring and maintenance. These systems are not likely to add up to enough energy to earn the credit, though.

  • It tends to be easier to earn this credit on low-rise buildings with relatively large roof areas, because they often have large unobstructed areas for installing solar panels.

  • Onsite electricity generation is one of the most visible ways to demonstrate a building owner’s commitment to green building and a conscious attempt to reduce the building’s carbon footprint. A visible solar panel or wind turbine on the building rooftop is a strong statement in public and occupant relations.

  • When selecting a specific technology, consider the long-term operation and maintenance requirements. Some PV systems come with a 20-year warranty while wind turbines often require annual oiling and checkups. Solar thermal may require glass replacement in case of some accident.

  • Geothermal energy, which uses heat generated deep within the Earth, is considered renewable by LEED. But technologies that use the surface of the Earth as a heat source and sink for heating and cooling with heat pumps, are also commonly called “geothermal” or “geo-exchange,” and these don’t count.

  • You can double-dip with onsite renewable energy—in addition to this credit, it helps to offset total annual building energy use, contributing to EAp2, and EAc1, if using Option 1, Whole Building Optimization Energy Modeling.

  • Excess energy beyond the building energy demand can be sold using net-metering, but only at market electricity rate. The building owner cannot charge a premium for the renewable energy. If the excess energy is sold at a price higher than market rate because it carries a green premium, it cannot be counted towards this credit, because you’re selling the environmental attributes of the power as RECs for someone else to claim. Although a bit convoluted, you can claim that electricity by purchasing RECs from a Green-e certified source (similarly to EAc6: Green Power). These RECs can be generated by any energy source, such as solar, wind, or biomass, and doesn’t have to be same as the LEED project fuel source.

  • Fuel cells are often touted for renewable energy systems, but they consume hydrogen as fuel, usually from natural gas. They are only considered renewable if their hydrogen is generated by renewable sources.  

  • Energy from solid-waste incineration, also known as “waste-to-energy,” does not contribute to this credit. 

  • Cogeneration with natural gas as a fuel is not renewable energy.

  • Transportation energy use is not a factor in this credit. For example, biofuels generated onsite from waste cooking oil is not eligible if used for vehicles and not buildings. 

  • In the case of generating onsite electricity and waste heat with a renewable source, e.g. biomass generator, all of the generated energy may be considered as on-site renewable energy. Use the latest LEED Combined Heat and Power guidance to determine credit.

  • If a PV vendor purchases and installs system on the project site, then the project does not have ‘ownership’ of the renewable system. To obtain LEED credit, the project must get into a ‘power purchase agreement’ where the building buys the electricity from the PV vendor at or lower than market price. The electricity has to flow into the building. The PV vendor may not retain the Renewable Energy Credits (RECs) of the system. If they are retaining the RECs then the LEED project can’t claim credit under EAc2. This is done to avoid any double counting of renewable energy by one plant.

  • If a system is owned and operated off-site by the project owner with the project receiving the energy generated, then the project may be able to count that renewable energy towards LEED EAc2.

  • Energy produced by wood pellet stoves from untreated wood waste would qualify as renewable energy.

  • Wood harvested from a project site is considered ineligible as a fuel source for non-renewable energy and doesn’t count under EAc2.

Schematic Design

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  • Consider building design and optimized energy performance before finalizing renewable energy calculations. Use estimates of the project’s annual energy use and costs to help determine what percentage of onsite renewable energy will be required to meet the credit threshold. 

  • The key factors in implementing renewable energy for onsite generation include:

    • envelope optimization and efficiency;
    • studying feasibility; 
    • selection of appropriate technology;
    • optimizing the mechanical and onsite systems; 
    • integrated design development;
    • space and resource allocation;
    • budget allocation;
    • Identifying available incentives.

  • Consider space requirements and access. For PV, look for shadows, evaluate for optimal solar radiation and the angle of incidence during peak generating season. If possible, consider solar tracking system that follows the sun during the day and throughout the year. This would allow more electricity generated from the same area, though with more infrastructure cost. (See Resources.) 

  • For possible wind generation, consider any obstruction like nearby buildings or future planned developments. 

  • Many PV panels are very sensitive to shading, so shade on even a small part of the panel reduces its output significantly. Discuss the structural requirements with a qualified vendor and structural engineer. Some types of PV, such as thin-film, are less sensitive to shading, but are also less efficient overall. 

  • Initiate the process for financial support and subsidies. Some programs require applications early in the design period and designate only approved vendors. 

  • Compare the various available renewable energy technologies for cost, capacity, and project goals. 

  • Consider the onsite environmental impact of the technologies. Will wind turbines affect migratory birds? Will solar panels cause unwanted glare?

  • Determine an annual energy-cost estimate using your energy model, if developing one for EAc1: Optimize Energy Performance, or by basing it on the estimates of average building energy usage developed by CBECS—see the LEED Reference Guide.

  • Conventional developer-driven projects do not allow room for long payback. It is helpful to run a long-term cost-benefit analysis to estimate the savings after the first ten years of the installation, presenting onsite renewable system as a cost-effective investment to the future occupants. Spec projects can still pursue this credit and install renewable energy with the promise of lower utility bills and future energy freedom to the occupants of the building. The cost can be transferred to the occupant either in the form of higher rent or fees, or an escrow account where the occupant pays monthly dues for the cost of installation over a period of time. It’s also possible to purchase the system on loan and transfer the loan to the future owners. Work creatively to reduce the financial impact and allow as much energy generation as possible. 

  • Current technologies for generating small-scale renewable energy systems have two major barriers: low efficiency and high installation expense. The expenses consist of the actual generating technology (photovoltaic panels, wind turbine, or a hydro plant) and the “balance of system” components: inverter, battery or grid-interface, and wiring. System components and wiring is often a major cost element. 

Design Development

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  • The renewable energy designer provides layout, sizing, electrical load requirements and other design parameters to the design team. Integrate these into the overall project design and check for impacts on structural design and mechanical system sizing. 

  • Solar thermal systemA solar thermal installation provides hot water at the Snowmass Recreation Center in Snowmass, Colorado.Backup power may be needed. For example, solar-thermal hot water may be combined with a hot water tank and a boiler. This will require integrated controls. A building management system can track which fuel is used when to optimize efficiency. 

  • If you are considering building-integrated systems that have PV integrated into windows, skylights, canopies, parking shades, or roof tiles, have the manufacturer and contractor do a constructability review. Some glazing manufacturers provide the technical input and work with the team to develop a custom product like BIPV glass laminate panels. (See Resources for more on BIPV.)

  • Include all renewable energy systems within the scope of commissioning when writing the RFP for a commissioning agent. 

  • Submeter renewable energy systems so that energy use is recorded and verified. Compare it with the rated capacity of the system. Include this within the scope of EAc5: Measurement and Verification. 

  • Be sure to design for adequate access to the systems, for maintenance and inspection after the project is completed.

Construction Documents

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  • Include the renewable energy systems in the specifications and construction documents. 

  • Make sure elements that are needed to attach the systems, such as anchors or flanges, are clearly called out in the appropriate drawings and specs because workers who aren’t installing the actual systems might not have experience with them. 

Construction

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  • Discuss the system with the construction team during bidding, and address any potential conflicts in construction issues and scheduling. 

  • Coordinate the project schedule to account for installation and connection requirements of the renewable energy systems. Often, when unfamiliar with the system, the construction team does not account for the additional time and interaction required with steel, electrical, mechanical and plumbing subcontractors. For example, the vendor, electrician, window contractor, and façade consultant all have to coordinate on the installation of glass-laminated PV. 

  • Schedule the installation to be completed before final commissioning, both to allow ample time for commissioning and for any changes or adjustments. 

  • Make final calculations of the estimated building energy loads. Confirm that renewable energy generation capacity is 1% of building energy, at minimum for the LEED credit, or that the project’s goals are met.

  • Double-check that you will earn any incentives or rebates you are counting on.

Operations & Maintenance

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  • Obtain warranty information and a maintenance contract with the system installer for future visits. Some of the technologies such as hydroelectric and wind include moving parts that will need regular maintenance. Solar panels need to be cleaned of bird droppings and snow to operate at highest possible efficiencies. Incorporate these measures into the facility maintenance manual.

  • USGBC

    Excerpted from LEED 2009 for Core and Shell Development

    COPYRIGHT © 2009 BY THE U.S. GREEN BUILDING COUNCIL, INC. ALL RIGHTS RESERVED

    EA Credit 2: On-site renewable energy

    4 Points

    Intent

    To encourage and recognize increasing levels of on-site renewable energy self-supply to reduce environmental and economic impacts associated with fossil fuel energy use.

    Requirements

    Use on-site renewable energy systems to offset building energy costs. Calculate project performance by expressing the energy produced by the renewable systems as a percentage of the building’s annual energy cost and use the table below to determine the number of points achieved.

    Use the building annual energy cost calculated in EA Credit 1: Optimize Energy Performance or the U.S. Department of Energy’s Commercial Buildings Energy Consumption Survey database to determine the estimated electricity use.

    The minimum renewable energy percentage for each point threshold is as follows:

     

    Percentage Renewable Energy Points
    1% 4
     
     
     

    Potential Technologies & Strategies

    Assess the project for nonpolluting and renewable energy potential including solar, wind, geothermal, low-impact hydro, biomass and bio-gas strategies. When applying these strategies, take advantage of net metering with the local utility.

Publications

Energy Information Administration Electricity Consumption and Price Data

Charts showing total U.S. energy consumption and U.S. residential electricity prices.

National Renewable Energy Laboratory (NREL)—Building Integrated PV Research (BIPV)

Compilation of research and technological breakthroughs in BIPV.

U.S. Department of Energy, Energy Efficiency and Renewable Energy, Renewable Energy Maps and Data

The maps and data section of DOE’s EERE website provides information on regional distribution of 
renewable energy sources and technologies in the United States. 

Energy Information Administration Electricity Consumption and Price Data

Charts showing total U.S. energy consumption and U.S. residential electricity prices.

Web Tools

U.S. Department of Energy—Energy Efficiency and Renewable Energy Maps & Data

Maps and data showing statistics, trends, and the availability of renewable energy resources throughout the United States.

North American Board of Certified Energy Practitioners (NABCEP) Installer Locator

Interactive map to help consumers find certified solar PV and solar thermal installers.

PV Watts Performance Calculator for Grid-Connected PV Systems

Helps non-experts to quickly obtain performance estimates for grid-connected PV systems.

U.S. Department of Energy—Energy Savers: The Economics of a Small Solar Electric System

Covers cost considerations for PV systems.

PV Watts Solar Calculator

Links to multiple educational tools for examining cost and performance of various energy-efficient and solar energy technologies and products.

Wisconsin Focus on Energy—Renewable Energy Site Assessment

Provides guidance for determining renewable energy potential of residential and non-residential sites.

U.S. Department of Energy—Green Power Network: Net Metering Policies

Resources on net metering laws, policies, and guidelines.

U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy

This website is a comprehensive resource for U.S. Department of Energy information on energy efficiency and renewable energy and provides access to energy links and downloadable documents. 

U.S. Department of Energy—Energy Savers: The Economics of a Small Solar Electric System

Covers cost considerations for PV systems.

National Renewable Energy Lab Tools

This comprehensive website provides energy data and tools that can assist in learning more about our main renewable energy technologies and their uses. Evaluate solar and wind potential with the listed tools under the Technology Analysis Models and Tools.

RETscreen

RETScreen 4 is an Excel-based clean energy project analysis software tool that helps decision makers quickly and inexpensively determine the technical and financial viability of potential renewable energy, energy efficiency and cogenerationThe simultaneous production of electric and thermal energy in on-site, distributed energy systems; typically, waste heat from the electricity generation process is recovered and used to heat, cool, or dehumidify building space. Neither generation of electricity without use of the byproduct heat, nor waste-heat recovery from processes other than electricity generation is included in the definition of cogeneration. projects.

Transol

Transol is a tool available for a fee for design, calculation and optimization of solar thermal water systems.

U.S. Department of Energy—Other Renewable Energy Tools

A collection of renewable energy building analysis tools.

Technical Guides

California Energy Commission—A Guide to Photovoltaic (PV) System Design and Installation

Detailed description of design considerations and installation instructions for PV systems.

Building-Integrated Photovoltaic (BIPV) Designs for Commercial and Institutional Structures: A Sourcebook for Architects

Illustrates 16 case studies across U.S. that incorporate BIPV and prepares readers with common BIPV terminology, pitfalls, and design basics.

California Solar Center—Solar Power Purchase Agreement Guide

Free article explaining how  third-party providers can install and maintain solar electrical systems on private property.

ENERGY Guide

This website provides information on different power types, including green power, as well as general information on energy efficiency and tools for selecting power providers based on economic, environmental, and other criteria.

Organizations

Solar Energy International

Links to publications, workshops, courses, outreach programs and other renewable energy education opportunities.

Low Impact Hydropower Institute

A non-profit organization that supports a voluntary certification program designed to help identify and reward hydropower dams that are minimizing their environmental impacts.

National Center for Photovoltaics

NCPV provides clearinghouse information on all aspects of photovoltaic systems. 

Database of State Incentives for Renewables and Efficiency (DSIRE)

Comprehensive listing of federal, state, local, and utility incentives that subsidize renewable energy use and energy efficiency.

American Wind Energy Association

A national trade association that provides resources and information about the domestic and international wind industry.

Articles

Low Emissions, Quick Energy Payback for Thin-Film PV

A BuildingGreen.com article about a 2008 study showing that all current photovoltaic technologies offer at least an 89% reduction of air emissions compared with conventional electricity while also offering an energy-payback time of less than three years.

Photovoltaic (PV) Calculator

Use of photovoltaic (PV) electricity is the most common way to earn LEED points. This spreadsheet helps you analyze how much PV you need to earn LEED points, what it will cost, and how much it will reduce your project's carbon emissions.

Renewable Energy Feasibility

Careful analysis of renewable energy feasibility is required for most projects. The example shown here was for a 20-kW system on a commercial building.

LEED Online Forms: CS-2009 EA

The following links take you to the public, informational versions of the dynamic LEED Online forms for each CS-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.

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."

The following links take you to the public, informational versions of the dynamic LEED Online forms for each CS-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.

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."

Design Submittal

PencilDocumentation for this credit can be part of a Design Phase submittal.

Photovoltaic Project Work

Sample documents showing PV infrastructure and calculations with an onsite PV project.

37 Comments

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BH .
Apr 23 2013
LEEDuser Member
626 Thumbs Up

Biomass from energetic crops

Hi,

does LEED recognize the biomass from energetic crops such like:
-short rotation coppice (Poplar and willow include)
-Grasses and non-woody energy crops (Miscanthus and Hemps included)

Thanks for help

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Marcus Sheffer LEED Fellow, 7group Apr 23 2013 LEEDuser Expert 20809 Thumbs Up

Eligible biomass includes agricultural crops. This is not very well defined. Sounds like you may be able to make the case that your fuel sources come under this type.

It is likely that you would need to own the fuel source in order to claim its use but there are exceptions to the on-site nature of the source. You might also check the LEED Interpretations to see if any of these sources have been formally asked about before.

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BH . May 06 2013 LEEDuser Member 626 Thumbs Up

Marcus you said that I need to own the fuel source, what does it mean ?

I know that the CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. operator buys biofuels from the suppliers, is that not recognized by LEED ?

Do you know if UGBC published some paper about LEED recognized Biofuels?

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Marcus Sheffer LEED Fellow, 7group May 06 2013 LEEDuser Expert 20809 Thumbs Up

I was not aware that you were taking about a CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. situation. Are you using the DES v2 guidance for how to include CHP in your models? If so there is some guidance on how to count renewables.

Other than looking through the LEED Interpretations I am not aware of any other source of information.

Post a Reply
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Tuana Papile
Apr 02 2013
LEEDuser Member

How many credit points does one get by offsetting 7%.

By using on-site renewable energy for 7% of the total energy, do we get now 7 points compared to the 4 points for NC?
Thank you

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Marcus Sheffer LEED Fellow, 7group Apr 03 2013 LEEDuser Expert 20809 Thumbs Up

Looks like you get 4 points for 7%, see credit language above.

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Bill Swanson PE, LEED AP, Integrated Architecture Apr 03 2013 LEEDuser Expert 10086 Thumbs Up

Check the last comment on this page. There is some confusion about the value of points for different levels of renewable energy.

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Marcus Sheffer LEED Fellow, 7group Apr 03 2013 LEEDuser Expert 20809 Thumbs Up

Yep your right Bill the credit language above is incorrect. It should be 1% for 4 points.

For 7% you would still get 4 points and be eligible for an 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. ID credit.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Apr 04 2013 LEEDuser Moderator

USGBC had this showing incorrectly in its credit library, which we draw from. I asked them to correct it, and I corrected our display. It's 4 points for 1%.

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Tuana Papile Apr 04 2013 LEEDuser Member

Does it mean between 1% and 4%(including) we get 4 points, and starting with 5% we get 1 more point as EP?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Apr 04 2013 LEEDuser Moderator

See the diagram at the top of the page.

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Marcello Polverino M.Eng. ARCADIS
Dec 12 2012
Guest

CHP biofuel certifications

Hi LEED-User,

I would like to know which documents I need to provide to the USGBC for a block heat and power plant fueled with biogas?

Thanks
Best wishes from Hanover (germany)

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Marcus Sheffer LEED Fellow, 7group Dec 12 2012 LEEDuser Expert 20809 Thumbs Up

You will need to justify the fuel mix used to generate the biogas against the allowable renewables. You will also need to explain how it is generated on-site or is in alignment with the LEED Interpretations which allow for some off-site renewables.

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Marcello Polverino M.Eng., ARCADIS Mar 13 2013 Guest

Hello Marcus,

do they know what the biogas criteria in locations outside the United States (Germany) must meet? Are there special requirements?

Thanks
Marcello

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Mar 13 2013 LEEDuser Moderator

Marcello, the requirements are discussed in the LEED Reference Guide, as well as in the Bird's Eye View tab above.

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Marcus Sheffer LEED Fellow, 7group Mar 13 2013 LEEDuser Expert 20809 Thumbs Up

International project must meet the same requirements as US based projects.

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Marcello Polverino M.Eng., ARCADIS Mar 15 2013 Guest

Hello together,

we have a CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. station, that runs on biogas, this is on a campus, but NOT in the Project Boundary. Is this ok and if so where is it written.

FYI: It is no campus certification.

Thanks

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Mar 15 2013 LEEDuser Moderator

Marcello see the guide to campuses, the district energy systems (DES) guidanace, and MPR3. Searching this site and USGBC's site should help you find what you need.

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Katie Mesia Regional Director of Sustainability Gensler
Oct 05 2012
LEEDuser Member
58 Thumbs Up

Geothermal (Sometimes you're in, sometimes you're out!)

We are in schematic design on a CS project. The project will have underground parking and will use piles as a foundation. Because they are digging so deep we looked in to using geothermal piles and found that they would pay back in around 9 months, Fantastic! Except… we also found that they are not eligible for the renewable energy credit.

Here are some bits of information I have found:

LEED allows you to take credit for technologies that generate electricity and heat from sun, wind, water flows, and waste biomass. It also allows certain thermal technologies, such as solar hot water, concentrating solar collectors, biomass, and geothermal (extraction of heat from within the Earth, not ground-source heat pumps).

You can double-dip with onsite renewable energy. In addition to earning this credit, renewable energy helps to offset total annual building energy use, contributing to EAp2 and EAc1, if using Option 1: Whole Building Energy Simulation.

I am still looking for a deeper explanation for my client on why one type of geothermal is in while the other is not even though both are reducing the building consumption through energy inherent in the natural world.

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Marcus Sheffer LEED Fellow, 7group Oct 05 2012 LEEDuser Expert 20809 Thumbs Up

Technically they are not both geothermal even though ground source heat pumps are often incorrectly referred to as geothermal.

Ground source heat pumps rely on vapor compression cycles which run on conventional electricity. So this is more of a hybrid system with only a portion of "heat" provided by the Earth.

True geothermal (in areas with hot springs and geysers and volcanos) is typically at pressures and temperatures which allow it to be used without requiring any or very minimal electricity.

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Katie Mesia Regional Director of Sustainability, Gensler Oct 10 2012 LEEDuser Member 58 Thumbs Up

I recived this response from USGBC:

Thank you for the inquiry, asking about geothermal heat pumpA type of heating and/or cooling equipment that draws heat into a building from outside and, during the cooling season, ejects heat from the building to the outside. Heat pumps are vapor-compression refrigeration systems whose indoor/outdoor coils are used reversibly as condensers or evaporators, depending on the need for heating or cooling. In the 2003 CBECS, specific information was collected on whether the heat pump system was a packaged unit, residential-type split system, or individual room heat pump, and whether the heat pump was air source, ground source, or water source. systems. It's a common question, and we are glad to address it.

Geothermal heat pump systems are eligible for use within the Energy Model for EAp2/c1, but are not eligible as "renewable energy systems" for EAc2. This type of geothermal energy takes advantage of site conditions for increased energy efficiency in much the same way that seasonal temperature ranges allow buildings located in moderate climates to employ economizers and take advantage of unconditioned supply air. These systems reduce the need for mechanical space conditioning but do not represent a renewable energy generation source. The reference to 'geothermal systems' in the Design Approach section of EA Credit 2 concerns the use of high temperature geothermal energy for the generation of electricity.

The basis of EAc2 is on-site renewable energy generation. Site conditions that allow for economizer use or geothermal heat pump systems reduce grid draw, but do not generate energy, and are not eligible as renewable energy systems. The intent of EAc2 is to encourage and recognize increasing levels of on-site renewable energy self-supply to reduce environmental and economic impacts associated with fossil fuel energy use. More detailed information about the eligible and in-eligible systems for EAc2 is available under the implementation section for EAc2, on page 291 in the LEED 2009 BD+C Reference Guide.

The contributions of these systems toward energy-efficiency are reflected in project-wide energy efficiency levels and facilitate the achievement of EA Prerequisite 2 and EA Credit 1.

You may also want to refer to LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org. # 5976 (https://www.usgbc.org/Login.aspx?REFERRER=/leedinterpretations/lilanding...) which states that:
"The LEED Reference Guide v2.1 states that in order to qualify as renewable energy under EAc2, geothermal energy (hot water / steam) must be used to generate electricity. As the described application does not generate electricity, it does not qualify as a renewable energy source under the requirements of this credit. The energy savings associated with the proposed strategy may, however, be incorporated in the calculations for EAc1, Optimize Energy Performance." LI 5060 provides similar guidance.

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Marcus Sheffer LEED Fellow, 7group Oct 10 2012 LEEDuser Expert 20809 Thumbs Up

The Interpretation is a bit dated in one respect. Geothermal used directly as a heat source would also qualify under EAc2.

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Pedro Ribeiro Director of Sustainability Edifícios Saudáveis Consultores
Sep 07 2012
LEEDuser Member
145 Thumbs Up

Reference for the building annual energy cost

In a Core&Shell project, the percentage of renewable energy integration shall be refered to the total building energy use (including tenants areas) or only to core and shell energy use ?

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Marcus Sheffer LEED Fellow, 7group Sep 07 2012 LEEDuser Expert 20809 Thumbs Up

It is based on the whole building energy use.

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Emmanuel Pauwels Owner Green Living Projects s.l.
Jul 27 2012
LEEDuser Member
962 Thumbs Up

How to calculate %

The reference for the calculation is total energy cost. The output of an array of PV panels is in 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.. How do you convert the PV kwh to USD in order to calculate the % considering the energy is not sold but auto-consumed?

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Marcus Sheffer LEED Fellow, 7group Jul 27 2012 LEEDuser Expert 20809 Thumbs Up

Assuming you are doing an energy model. The energy model uses a utility rate of some sort. From the output of the energy model you determine the virtual rate in $/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.. This rate is applies to the projected PV output to give you the USD.

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Emmanuel Pauwels Owner, Green Living Projects s.l. Jul 29 2012 LEEDuser Member 962 Thumbs Up

Marcus,
We are doing an energy model indeed. Thanks for your reply which was helpful

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Emmanuel Pauwels Owner Green Living Projects s.l.
Jul 27 2012
LEEDuser Member
962 Thumbs Up

PV in construction phase

We have filed for design submittal and are moving into construction phase. The client decided to integrate PVs in the project. Will it be possible to apply for this credit in the construction phase although we did not submit it in design phase?

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Marcus Sheffer LEED Fellow, 7group Jul 27 2012 LEEDuser Expert 20809 Thumbs Up

Yes you can just submit the credit along with the construction credits.

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Alicja Bieszyńska Skanska
Nov 22 2011
LEEDuser Member
538 Thumbs Up

1% from 15%?

I'm working on a Core and Shell project and recently I was given the energy model made for us by a consultant. Although the scope of the project is only Core and Shell, the model covers the whole building. It's OK.

Today the Client decided that he wants to implement photovoltaic cells on the facade (= on-site renewable energy) and he asked me to calculate how much energy needs to be generated by those cells, in order to fulfill LEED requirements.

Right now I am wondering if I should:
a) take the whole building energy use and cost and multiply by 1%, or
b) take the 15% of the whole building energy use and cost, in order to have Core and Shell energy usage, and multiply this number by 1%.

For those who don't know where the 15% came from, in Green Power credit it is said that if you don't know what's the Core and Shell energy use you take 15% of the whole building energy use (correct me if I'm wrong, but I'm quite sure it's like that).

As you can imagine, it's quite a difference to take 1% or 1% from 15% of the building energy use/cost.

Please advice if this rule also applies to the on-site renewable energy credit.

Thanks!

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Marcus Sheffer LEED Fellow, 7group Nov 22 2011 LEEDuser Expert 20809 Thumbs Up

For EAc2 you are required to produce 1% of the building total energy use (tenant load included) using on-site renewables.

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Severin Lenel
Jun 01 2011
LEEDuser Member
137 Thumbs Up

Developer Owned On-Site Renewable Energy Sold to Tenants

We are working on a LEED CS project where the investor will sell the energy produced on-site by photovoltaic systems to the tenants in the project building, according to internal fees at a premium rate compared to the market rate of non-renewable energy (though a typical rate for local renewable energy). No renewable energy will be delivered to the grid. The only energy sold will be directly to the tenants for energy consumption in the project building. The potential to buy renewable energy produced on-site will be outlined in the tenant design and construction guidelines (the primary tenant is already pursuing LEED CI). As long as all the renewable energy is produced and used on site, is charging the tenants in this manner eligible for LEED CS EAc2?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Nov 21 2011 LEEDuser Moderator

Severin, I would definitely say it is eligible.

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Sayeed Muhammad Principal Consultant Green Building Consultants (S) Pte Ltd
Mar 13 2011
Guest
144 Thumbs Up

Time line for PV installation

In our project we intend to install PV panels for 300KWp capacity. Its a NC2009 project aiming for LEED platinum. The building is office building with a 24hrs cafeteria. The building has been completed and we are ready (except the PV stuff) to submit the project for GBCI review. We are counting 7+7 = Total of 14 pts through PV. However the procurement and PV installation will take another 6 months. Is it possible to submit the project for GBCI review before completion of PV and get Platinum. The Client's Management has a KPI to achieve Platinum by end of June 2011.
My question is whether GBCI will allow for some time say 6 months to 12 months for PV installation and award the points now with client commitment to install 300KWp PV panels. Any one has experience with the time line for PV installation?

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Kimberly Frith Sustainability Consultant, Alto Sustainability, LLC Apr 27 2011 LEEDuser Expert 1624 Thumbs Up

Since this credit is reviewed during the design phase, the timeline of PV installation shouldn't affect achieving this credit. As long as it's on the drawings, planned and specified to be installed, and you have the owner's commitment to install the system, that should be sufficient.

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Tatjana Ernst LEED AP; Dipl.-Ing.
Nov 24 2010
Guest
476 Thumbs Up

who has to pay for the renewable systems?

Hi Everyone,

we have an Core&Shell office Building. The Owner is not providing any renewable energy source but the tenant wants to install Photovoltaic systems on the roof.
Can we use this for Credit 2?
Or do the owner of the project have to participate on the costs of the Photovoltaic system?

Many thanks for your answers,
Tatjana

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Dec 07 2010 LEEDuser Moderator

I'm confused—is the project a LEED-CI or LEED-CS project? For CS, you could apply it here. For LEED-CI, it would fall under SSc1.

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