NYS Clean Heat load calculation requirements

If you are a participating contractor, the load calculation is not paperwork you file after the fact. It is the document that decides whether your customer's rebate gets paid, and it is read by someone whose job is to check it against a published set of rules. Those rules are spread across three separate PDFs and a zip code lookup tool. This page puts them in one place, in the order you actually hit them, with each requirement attributed to the document it comes from so you can point a reviewer at the same line.

Every figure below is quoted or paraphrased from the program documents listed in Sources. Nothing here is our interpretation dressed up as a rule. Where the program documents disagree with each other, we say so.

1. Which methodology the program accepts

The Load Calculation Guidance is explicit about method, and it splits by building type:

• Residential: ACCA Manual J, 8th Edition.
• Commercial: ACCA Standard 183-2007.
• Anything else: "other approved calculation methods in accordance with the Clean Heat Program Manual." An alternative methodology has to be submitted to Program staff showing sign off from the authority having jurisdiction.

The Program Manual pins the editions precisely: "Residential heat pumps shall be sized in accordance with ACCA Manual S (2023) based on design loads calculated in accordance with ACCA Manual J (8th Ed., 2016), or an alternative method approved by the AHJ" (Section 3.2). That pairing matters. A Manual J alone does not satisfy the program: the load calculation feeds a Manual S selection, and the Manual S selection is what your equipment choice is judged on.

On sizing inputs, the guidance is blunt: "Residential equipment sizing shall be based on manufacturers' extended performance tables in accordance with ACCA Manual S, not based on nominal size or AHRI ratings." A 3 ton nameplate is not an answer. You need the manufacturer's capacity at your design temperatures, from engineering documentation or manufacturer software. Where that data does not exist, the Program Manual permits the NEEP Cold Climate Air Source Heat Pump List product sheet for NEEP-listed equipment, using the "Advanced Data/System Sizing" tool, and asks you to include the NEEP specification sheet with its version number in the application.

2. Design temperatures, and the plus or minus 5 F rule

This is the single most common place a calculation drifts out of compliance, because designers carry a favourite weather city between jobs.

The Program Manual states that calculation of the BHL "shall be at the 99% dry bulb heating design temperature for the most relevant ASHRAE (2021) location," and calculation of the Building Cooling Load (BCL) "shall be at the 1% dry bulb cooling design temperature for the same ASHRAE location" (Section 3.2).

The tolerance is where the enforcement lives. Outdoor design temperatures "should be within plus or minus 5 F of the Clean Heat program default for the project's location, based on the Clean Heat Weather Station Reference (zip code lookup tool)." The Load Calculation Guidance closes the obvious loophole directly: if the design professional chooses a different weather city or a different ACCA reference, "the design temperatures shall remain within 5F of the values for 99% heating and 1% cooling, for the site as shown in the CH weather station reference." You may pick your source. You may not pick a warmer winter.

Two documented overrides exist, and both require you to show your work. Design temperature requirements may be superseded by the local AHJ, and separately by manufacturer-specific requirements. In either case the applicant "must provide documentation citing the applicable" local or manufacturer requirement. An undocumented override is just a wrong design temperature.

Indoor conditions are a hard ceiling and floor, not a preference: "Indoor design temperatures for heating load calculations shall not exceed 72 F, and for cooling shall not be less than 75 F." Designing heating to 75 F indoors is a fast way to inflate a load and land above the 120 percent band described next.

3. The sizing bands: 100 percent, 120 percent, and the justification letter

Full load heating systems are defined as a system that satisfies at least 100 percent of the BHL of the project scope at design conditions. The Program Manual adds a distribution and coverage test alongside it: systems "shall be designed and sized to satisfy at least 100% of the BHL at design conditions, with the ability to distribute heat adequately across all occupied spaces in the project scope and serve at least 80% of the building's total square footage" (Section 3.2).

Above that, the bands are:

• Over 120 percent of BHL: "Systems with capacities above 120% of BHL may be subject to additional programmatic review."
• Heating dominant and over 120 percent of BHL, or cooling dominant and over 115 percent of BCL: "a system sizing justification letter is required." The letter is subject to the program's approval and must include an explanation for the oversizing from the participating contractor or project design engineer, plus any applicable information supporting the need for it.
• BCL higher than BHL: the system "shall be sized to satisfy full BCL as required by Manual S and relevant municipal or state code."

Two category-specific numbers are easy to miss and both are load calculation questions:

• Category 4 (partial to full load): "The new equipment must satisfy greater than 50% of the total BHL at design conditions." The existing partial-load system plus the new elements together must meet the full load requirements of Section 3.2.
• Residential decommissioning (Categories 2b, 3, and 4): projects "may include electric resistance heating not to exceed 10% of BHL."

Read together, these define a narrow corridor: at least 100 percent of BHL, ideally under 120 percent, with a written defence required if you exceed it. That corridor is why the quality of the underlying Manual J matters so much. An inflated load does not just cost your customer equipment money, it can push the selection into a band that triggers review.

4. What must NOT be in the calculation

The Load Calculation Guidance lists component loads that should not be included at all. This list is short, specific, and a frequent source of rework:

• Humidification loads.
• Hot water piping distribution losses.
• Adiabatic surfaces, meaning surfaces with no heat transfer, such as party walls within or between buildings, and floors or ceilings between conditioned floors.
• Duct losses and gains where the indoor equipment is ductless, or where ducts are located inside conditioned space.
• "Multiplicative or additive safety factors with no defined source."

That last one is the rule that catches habitual padding. If your software or your practice adds a 10 percent cushion, it has to have a defined source, or it does not belong in a Clean Heat submission.

5. Component load rules that change the number

Ventilation, net of heat recovery

Ventilation loads must be supported by mechanical schedules, and the calculation must account for heat recovery by subtracting recovered energy from the total ventilation load. The guidance gives a worked example: if the total ventilation heating load is 10,000 Btu/h and the ERV has a sensible effectiveness of 75 percent, the load calculation for the heat pump should include only the remaining 2,500 Btu/h. Submitting the gross ventilation load with an ERV on the schedule is an obvious oversizing flag.

Infiltration defaults

Unless supported by project-specific blower door testing, heating and cooling infiltration shall be no greater than the following natural ACH values:

Clean Heat publishes separate Infiltration Guidance for deriving design infiltration from blower door results, available on the contractor resources page.

Envelope, geometry, and internal gains

• Enclosure component loads should use R values consistent with final architectural plans for new construction or gut rehab, and verified existing conditions for retrofit. The guidance publishes vintage-based default R values and window U-factor and SHGC defaults for buildings where insulation is not accessible for inspection, and instructs that if any evidence of additional insulation exists, it must be included.
• All documented energy-efficient features and specifications shall be accounted for when defining component loads.
• Internal gains above normal levels, such as industrial process heat, shall be accounted for as offsetting design heating load. Conversely, heating load calculations must account for cold processes or equipment that absorb heat in the zone, for example indoor unitary heat pump water heaters or some refrigerated cases.
• Surface areas, geometry of exterior components, and floor area used in the loads must be consistent with architectural plans. This is the check a reviewer can perform fastest, by comparing your envelope takeoff to the drawings in the same application.

6. Multi-zone systems and the block load report

Each outdoor condensing unit or central system should be sized for the dominant heating or cooling load of its corresponding zone. Where one outdoor unit conditions multiple zones, such as a VRF or multi-zone system, the block load of the entire conditioned space must be used, which is generally smaller than the sum of individual zone loads.

To verify the block load was calculated correctly, the guidance requires the submission to include a complete engineering load calculation report that does three specific things:

1. Clearly identifies the individual heating and cooling loads for each zone, detailing inputs for envelope, solar gain, internal loads (lighting, occupants, plug loads), and ventilation.
2. Demonstrates how the non-coincident timing of the zonal peaks was used to calculate the overall system block load.
3. Confirms that the selected outdoor unit capacity is based on that calculated block load, not the sum of individual zone peak loads.

If your report shows only a total, it does not satisfy item 2, and a reviewer cannot confirm item 3.

7. Con Edison territory: floor by floor is mandatory

The statewide Load Calculation Guidance carries a one-line rule with real consequences: "Con Edison requires all Manual J submittals to follow a floor-by-floor load calculation methodology."

Con Edison's own Program Manual (Version 6, September 10, 2024) repeats it without qualification in the program pathway section: "All projects will require a floor-by-floor Manual J Load Calculation report." Its required document list names the deliverable explicitly as "Floor by Floor Manual J," described as the latest heating and cooling load calculations showing the design and appliance selection were performed per ACCA Manual J, ANSI/ASHRAE/ACCA Standard 183-2007 (RA2017), or another code-approved equivalent depending on building type.

Con Edison also requires that projects combining GSHP with ancillary ASHP or AWHP "make note of the difference by square footage and heating load in the Manual J floor by floor plan." If you serve Westchester or New York City, a whole-building block Manual J is not a submittable document, no matter how correct the arithmetic is.

8. How the calculation is submitted

The Program Manual's required document list describes the Manual J deliverable as heating and cooling load calculations performed per ACCA Manual J or another code-approved equivalent computation, "with appropriate allocation and identification for separate dwelling units," consistent with program requirements. It adds a format instruction that is easy to overlook: "Manual J calculations should be submitted in PDF format, unless otherwise requested."

A native software file, a spreadsheet, or a screenshot is not the requested artifact. Export the full report.

9. The compliance checklist

Before you attach the load calculation to an incentive application, confirm every line:

• Residential loads per ACCA Manual J, 8th Edition (2016); commercial per ACCA Standard 183-2007.
• Equipment selected per ACCA Manual S (2023) from manufacturer extended performance data, not nominal or AHRI capacity.
• Outdoor design temperatures within plus or minus 5 F of the Design Temperature Lookup Tool result for the project zip code, at 99 percent heating and 1 percent cooling.
• Indoor heating design at or below 72 F; indoor cooling design at or above 75 F.
• System satisfies at least 100 percent of BHL and serves at least 80 percent of total square footage.
• If above 120 percent BHL (heating dominant) or 115 percent BCL (cooling dominant), a signed system sizing justification letter is attached.
• No humidification, hot water piping losses, adiabatic surfaces, ductless or in-conditioned-space duct losses, or undefined safety factors.
• Ventilation load reported net of heat recovery, supported by mechanical schedules.
• Infiltration at or below the default natural ACH for the building type, or backed by blower door testing.
• Envelope R values and geometry consistent with plans or verified existing conditions.
• Multi-zone submissions include the zone-by-zone breakdown, the non-coincident peak derivation, and confirmation the outdoor unit matches the block load.
• Con Edison projects: floor-by-floor methodology.
• Any AHJ or manufacturer override of design temperatures is documented with a citation.
• Report exported as PDF.

Sources

Every requirement on this page comes from one of the following program documents. We cite them rather than link to hosted copies so you always pull the current revision from the program's own resources page.

• NYS Clean Heat Statewide Heat Pump Program, Load Calculation Guidance. Published December 1, 2023, revised July 15, 2025. Source for methodology, design temperatures, excluded component loads, infiltration and envelope defaults, ventilation net-of-recovery, the block load report contents, and the Con Edison floor-by-floor rule. Available from cleanheat.ny.gov under contractor resources.
• New York State Clean Heat Heat Pump Program Manual, Version 1, December 12, 2025. Section 2.1.1, Section 3.2, and the required documents list. Source for the Manual S (2023) and Manual J (8th Ed., 2016) editions, ASHRAE (2021) design conditions, the 100 percent and 80 percent square footage requirements, the 120 percent and 115 percent thresholds and justification letter contents, the Category 4 greater-than-50-percent rule, the 10 percent electric resistance allowance, and the PDF submission format.
• New York State Clean Heat, Con Edison Heat Pump Program Manual, Version 6, September 10, 2024. Source for the floor-by-floor Manual J requirement across all projects and the required document description.
• Clean Heat Design Temperature Lookup Tool (zip code weather station reference) and Clean Heat Infiltration Guidance, both available under the Air Source Heat Pump and Ground Source Heat Pump expanders at cleanheat.ny.gov contractor resources.

Program requirements change. This page reflects the documents as published on July 27, 2026. Always confirm against the current revision on the program's own site before submitting an application. Manual J, Manual S, and Manual D are ACCA standards; Manual J Pro is not affiliated with ACCA, NYSERDA, or any Program Administrator.

Get a Clean Heat ready load calculation

Manual J Pro produces permit-ready ACCA Manual J, Manual S, and Manual D reports for contractors who need a calculation that survives third-party review. If you are filing a Clean Heat application, we design to the program's own design temperatures, keep the sizing inside the corridor described above, deliver floor-by-floor output for Con Edison territory, and export the report as a PDF you can attach directly.

See what is included in each report, check the price for your project, or read our walkthrough of how Manual J, S, and D fit together for permit approval. If your customer is still deciding, our NYS Clean Heat homeowner's guide covers rebates and financing. Send us the plans and most reports come back in 24 to 48 hours.