MD NJ OH PA VA DC USA IL
Estimated annual output
Estimated annual revenue at per
· ·
Key metrics
Estimated system size
tons
Thermal energy delivered by system
mmBTU/yr
Renewable energy delivered
mmBTU/yr
Renewable share of delivered energy
Virginia Class I GREC basis
Verification segment, PJM GATS rule 4
Fleet rated cooling capacityBTU/h
Nameplate = cooling capacity / 12,000
Equivalent full load hours
Climate station of record · IECC zone
Annual HDD65 / CDD65deg-days
Design dry-bulb, winter / summer · basedeg F
Heating EFLH = HDD65 × 24 / |WDB − 65|hours/yr
Cooling EFLH = CDD65 × 24 / |SDB − 65|hours/yr
Estimated system size and capacity
Controlling envelope year · code of record
As-built envelope year, pre-code
SQFT per ton, code standard of recordsq.ft./ton
Est. system size = SQFT / SQFT per tontons
Capacity used = est. tons × 11,942.5 BTUh/tonBTU/h
Annual thermal demand
Heating season = heating EFLH × capacity usedmmBTU/yr
Cooling season = cooling EFLH × capacity usedmmBTU/yr
Delivered by systemmmBTU/yr
Renewable methodology
COP heating / EER cooling (ISO 13256-1)
COP cooling equivalent = EER / 3.413
Renewable fraction, heating / cooling
Renewable energy deliveredmmBTU/yr
= renewable mmBTU / 3.413MWh/yr
Revenue estimateper year

Revenue is gross annual credit revenue before any Flett Exchange transaction fee, and assumes the system operates as designed for a full calendar year.

Project detail
Project location
Placed in service
Installer of record
Ground loop type
Conditioned space
sq ft
Equipment
Fleet capacity (htg / clg)
As-built envelope year
Controlling envelope year
Code standard of record
Prototype
Basis and proxies
    Turn these credits into income

    Credits have to be registered and certified before they can be sold. Flett Exchange handles registration, minting and trading for geothermal owners, with no long-term contract and no setup fee. Apply for an account and we will confirm your project's eligibility.

    Apply for a GREC account

    Please pick your state and the closest municipality so that we can approximate your climate

    Count only heated and cooled space.
    Use the year of the last major envelope work if the walls, windows or insulation were replaced. This selects the code standard of record. Anything built before the 2006 USBC took effect is sized on the earliest code with a published envelope.
    Elect the conditioned-basement basis only if finished basement area is inside the square footage above. Elect unspecified if the building mixes foundations.
    How You Want to Enter Your Equipment:
    SQFT per Ton Basis:
    From the Manual J or the design report.
    US dollars per GREC
    Optional. Named on the memo so the derivation is clearly a credit basis for that programme, not a Virginia RPS claim.
    Where to send your report

    Flett Exchange GREC Calculator 2.0 · PJM GATS Appendix 5 Class 1 GEO methodology

    Want to learn more about Geothermal RECs? Read our guide to Geothermal RECs

    How the Geothermal REC Calculator works

    The Flett Exchange Geothermal REC Calculator estimates the Geothermal Renewable Energy Credits (GRECs) a ground-source heat pump earns each year, using the Virginia Class I geothermal method set out in PJM GATS Business Rules Appendix 5. It works through five steps, and your results and the PDF report show the figures behind every one.

    1. Full load hours. Heating and cooling degree days and design temperatures from the NOAA weather station nearest the project give the equivalent full load hours the system runs in a year.
    2. System size. The conditioned floor area divided by the square feet per ton published for the building's climate zone, construction year and foundation gives the estimated system size in tons.
    3. Capacity. The estimated tons multiplied by 11,942.5 BTU/h per ton give the capacity used.
    4. Thermal energy delivered. Full load hours multiplied by that capacity give the heating and cooling energy the system delivers in a year, in mmBTU.
    5. Renewable energy and GRECs. The heat pump's rated COP and EER set the renewable share of that energy. Renewable mmBTU divided by 3.413 is the annual output in MWh: one Virginia GREC per MWh.

    Geothermal REC Calculator FAQ

    What does the Geothermal REC Calculator estimate?
    +

    It estimates how many Geothermal Renewable Energy Credits (GRECs) a ground-source heat pump system earns in a year, and what they could be worth at a GREC price you choose. Alongside that it shows the estimated system size, the thermal energy the system delivers, the renewable share of that energy, and every step of the derivation.

    What is a Geothermal REC (GREC)?
    +

    A Geothermal REC is a tradable credit for the renewable thermal energy a ground-source (geothermal) heat pump delivers. In Virginia, one GREC represents one megawatt-hour of renewable thermal energy. Electricity suppliers buy GRECs to meet the geothermal carve-outs in state Renewable Portfolio Standards, which is what gives them a market value.

    Which states does the Geothermal REC Calculator cover?
    +

    It holds climate data for projects in Virginia, Washington DC, Maryland, Pennsylvania, New Jersey, New York, Ohio, West Virginia and Illinois. Virginia systems are estimated as Virginia Class I GRECs. Systems elsewhere run through the same method as a transparent credit basis for another programme; they do not earn Virginia RECs.

    What information do I need to use the calculator?
    +

    The placed-in-service date, the ground loop type, the town nearest the project, the conditioned floor area, the year the building envelope was built, the building type and foundation, and the heat pump make and model. If the model is not in the AHRI library you can type its rated capacities instead, or enter the system size in tons.

    Is the Geothermal REC Calculator free?
    +

    Yes. The calculator is free and there is no account to create. Enter your name and email address and your GREC Estimate arrives as a one-page PDF.

    How accurate is a Geothermal REC estimate?
    +

    It is an estimate, not a meter reading. Credit volumes are modeled from climate normals, published building code sizing standards and rated equipment performance, so the credits a system actually earns depend on how it is registered, verified and operated.

    What do I do after I get my GREC estimate?
    +

    Credits have to be registered and certified before they can be sold. Flett Exchange handles registration, minting and trading for geothermal owners, with no long-term contract and no setup fee. Apply for a GREC account and we will confirm your project's eligibility.

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