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HSPF2 Region IV and Region V: why two numbers
The same heat pump carries two heating ratings. They do not contradict each other: each one assumes a different winter. This guide shows what the standard puts in each region, which one resembles Montréal’s winter, and which one our cost estimates use.
ORION XLTH · 12,000 BTU
ASUH12KZAS / AOUH12KZAH1 · AHRI 214888802
See the product pageSix regions, six reference winters
HSPF2 is calculated for a reference winter. The U.S. Department of Energy (DOE) test procedure defines six, numbered I to VI. Tap a region: its design temperature, its heating hours and, for the two regions the NEEP record publishes, the HSPF2 of the example unit.
A diagram, not a geographic map: the regions are stacked from the coldest, at the top, to the mildest, at the bottom. Region VI is the Pacific Coast region. Montréal is placed by its design temperature.
Region V spends more hours in the cold
For each region, the standard splits the heating season into 5 °F bins and gives each bin’s share of hours. The two distributions are overlaid here. Tap a bin to compare.
Why more cold gives a lower rating
A heat pump’s efficiency drops as the outdoor temperature drops. The NEEP record of the example unit shows it at maximum capacity, from 8.3 °C to −26.1 °C. A reference winter with more cold hours therefore gives a lower average, and the calculation adds electric backup when the heat pump is no longer enough.
FUJITSU AIRSTAGE ORION XLTH 12,000 BTU, NEEP record no. 392122, “Max” column, read on November 10, 2026. COP there is calculated by NEEP from capacity and input power. The hour shares come from Table 20 of Appendix M1 as the DOE published it on January 5, 2017; the current version refers to the corresponding table of AHRI Standard 210/240-2024. The shares do not add up to 100%: the table enters zero for the two mildest bins.
Which of the two winters resembles Montréal’s
The six regions describe the climate of the United States: Montréal is not in them. Three reference points still let us place the city, and all three point to Region V.
The design temperature
Montréal’s is −23.1 °C according to Natural Resources Canada’s HOT2000 climate data (Montréal Intl station). Region V’s is −10 °F, or −23.3 °C; Region IV’s is 5 °F, or −15 °C.
Canadian regulations
In Canada, the minimum heating standard for split-system heat pumps is expressed in Region V: an HSPF2 of at least 6.0. In the United States, the same category must reach 7.5 in Region IV. Natural Resources Canada explains that it uses Region V to account for Canadian climate conditions.
The neighbours to the south
In its 2017 rule, the DOE places southern Vermont, for example, in Region V, and New York and New Jersey in Region IV. Vermont borders Québec, and the standard has no region colder than V.
What this does not mean. Region V remains a reference winter, the same for all units. It is not Montréal’s weather record, nor Saguenay’s or Gatineau’s. It is used to compare heat pumps under conditions close to ours, not to predict a bill.
Our cost estimates use Region V
On all our comparison pages, a heat pump’s heating electricity is estimated with its Region V HSPF2, never with its Region IV value. Here is why, and what this choice changes for the example unit.
- It is the reference winter closest to ours. Our method uses Montréal’s design temperature, −23.1 °C. Region V’s is −23.3 °C; Region IV’s is −15 °C.
- It is the region of Canadian regulations. The federal minimum standard is expressed in Region V HSPF2.
- It is the same rule for every unit. Each heat pump, of each brand, is calculated with the same region and the same formula: the amounts can be compared from one page to another.
One heating winter, example unit
How this amount is calculated
AirGreen method v1.1 of November 9, 2026, the same as on our comparison pages. A zone whose heat loss reaches 12,000 BTU/h ( kW) at −23.1 °C, heated around the clock: kW × 24 h × 4,167 degree-days ÷ (18 − (−23.1)) = kWh of heat (degree-days and design temperature: Natural Resources Canada, HOT2000 climate data, Montréal Intl station). Heat pump electricity: heat × 3.412 ÷ HSPF2. Electric baseboards: 1 kWh of electricity for 1 kWh of heat. Price: Hydro-Québec Rate D in effect April 1, 2026, average price of 9.104¢ per kWh, GST and QST included; network access charges are not counted. An estimate is used to compare units under the same conditions. The actual bill depends on the house, the insulation, the settings and the use; this amount is not a promise.
How the NEEP record names the two numbers
The record shows the two values one under the other: “HSPF2 (Region IV)” and “HSPF2 (Region V)”. A third line, “HSPF (Region IV)”, without the “2”, keeps the place of the former rating: do not confuse it with the other two.
On the record read on November 10, 2026, the + mark accompanies the Region IV value, the one used for U.S. compliance. The Region V value is shown without that mark; the record does not say why. Both lines come from the same record and the same AHRI certificate number.
For the rest of the record, field by field: How to read a NEEP record and an AHRI certificate. For the three seasonal ratings: SEER2, EER2, HSPF2.
What we are asked about the two regions
An HSPF2 with no region stated: which one is it?
You cannot know without checking. AHRI Standard 210/240 states that HSPF2 varies by region and that Region IV is used for compliance in the United States; Canadian regulations are expressed in Region V. The unit’s NEEP record shows both values: compare the advertised number with the two lines.
Can one region be converted into the other?
It is not necessary: the record gives both. For the example unit, 12.7 ÷ 10.1 gives a ratio of 1.26. The two minimum standards, 7.5 in Region IV in the United States and 6.0 in Region V in Canada, give 1.25. These are observations, not a rule: each unit is calculated separately for each region.
Is Montréal officially in Region V?
The regions of the test procedure describe the climate of the United States; they do not classify Canadian cities. What is official is that Canadian federal regulations express their minimum standard in Region V HSPF2, and that Montréal’s design temperature published by Natural Resources Canada, −23.1 °C, is 0.2 °C from Region V’s.
Does Region V HSPF2 say what the unit delivers at −25 °C?
No. It is an average over the whole season, where very cold hours are rare: in Region V, the bins below −17.8 °C account for 3.6% of the hours. For a specific temperature, read the capacity points on the NEEP record. For the example unit, the coldest published point is at −26.1 °C: 12,200 BTU/h at maximum, with a COP of 1.81.
Do both regions count electric backup?
Yes. In both cases, when the heat pump does not cover a bin’s heating need, the calculation adds electric resistance heat to fill the gap, and that electricity goes into the rating. Region V has more cold hours, hence more occasions to use it.
And Regions I, II, III and VI?
These are milder winters: their design temperatures range from 2.8 °C to −8.3 °C. The NEEP record publishes HSPF2 only for Regions IV and V, and our pages use only those two values.
Region IV and Region V, value by value
The region values come from Table 20 of DOE Appendix M1 (rule of January 5, 2017). The example’s values come from NEEP record no. 392122, read on November 10, 2026.
| Value | Region IV | Region V |
|---|---|---|
| The reference winter | ||
| Outdoor design temperature | −15 °C (5 °F) | −23.3 °C (−10 °F) |
| Heating load hours | 1,701 h | 2,202 h |
| Coldest bin countedRepresentative temperature | −22.2 °C (−8 °F) | −30.6 °C (−23 °F) |
| Share of hours below −6.7 °C | 8.4% | 20.5% |
| The calculation | ||
| Threshold where the heating need starts | 12.8 °C (55 °F) | 12.8 °C (55 °F) |
| Slope factor, variable speed | 1.07 | 1.08 |
| Who uses it | ||
| Minimum standard, split-system heat pumpsRequired HSPF2 | United States: 7.5 | Canada: 6.0 |
| AirGreen cost estimates | Not used | Yes |
| The example: FUJITSU AIRSTAGE ORION XLTH 12,000 BTU | ||
| HSPF2 on the NEEP record | 12.7 | 10.1 |
| Estimated heating winterAirGreen method v1.1, 12,000 BTU/h zone | ||
The minimum standards are those Natural Resources Canada gives for split-system heat pumps (technical bulletin of May 2021 and Regulations page modified October 28, 2025). They can change: only the official texts are authoritative.
The example unit is on AirGreen’s site.
Its product page gives the model numbers; its AHRI number leads to its NEEP record. For a project, talk it over with our team: bring the area to heat, your current heating and the planned outdoor location.
Where each number comes from
Data verified on November 10, 2026. This guide explains two heating ratings; it ranks neither units nor brands. The DOE, AHRI and Natural Resources Canada texts are summarized: only those texts are authoritative, and they can change.
Trademarks. FUJITSU AIRSTAGE, ORION XLTH, AHRI, NEEP and ENERGY STAR are trademarks of their respective owners. Logos are used only to identify the product shown. AirGreen is a dealer of the equipment brand cited; this page is not produced, sponsored or approved by the manufacturer, AHRI or NEEP.
Photos: AirGreen and manufacturers, for identification.
Does a value look wrong? Write to us: every reported value is verified again.