Skip to main content
Emergency service 24/7
(708) 673-5633
Call Request service
Guide Updated October 7, 2026

HSPF4 vs HSPF5: Which Heat Pump Rating Fits Your Climate?

HSPF2 is the standard heat pump heating score, calculated for a moderate-climate region.

Key points

  • HSPF2 is the standard heating score, calculated for climate region 4.
  • Compare region 4 with region 4; if a region 5 figure is shown, compare region 5 with region 5.
  • Check cold-climate performance and the backup heat, not just the score.

HSPF is the heating score of a heat pump. A higher score means the heat pump gives more heat for the electricity it uses over a winter.

HSPF2-4 vs HSPF2-5: the difference

The standard score today is written HSPF2. It is calculated for climate region 4, which has a moderate winter. Some product listings also show a second figure for region 5, a colder winter. The two numbers are not two kinds of heat pump — they describe the same equipment under different climate assumptions.

A region 5 figure, where a maker shows one, is usually lower, because cold air makes a heat pump work harder. A lower region 5 number does not mean a worse machine. It means a colder calculation.

The rule when you compare two heat pumps: compare region 4 with region 4, or region 5 with region 5. Never mix them.

The same air-source heat pump operating in moderate and colder winter conditions
What to notice: A seasonal score changes with the climate assumptions. For northern Illinois, also compare low-temperature capacity and the planned backup heat. Conceptual illustration; exact equipment and layout vary.

Where you see these numbers

You find them in the maker’s product details and in official product listings. Listings write the regional figures in several ways, for example HSPF4 and HSPF5, HSPF2-4 and HSPF2-5, or HSPF2 (Region IV) and HSPF2 (Region V). Before you compare, check which region a number belongs to.

HSPF and HSPF2

Maker pages today show scores written HSPF2; older models and old quotes may still show HSPF. The two numbers are not interchangeable: compare HSPF2 with HSPF2.

Which number is the standard one

  • The standard HSPF2 score is the region 4 figure.
  • Heat pumps with the ENERGY STAR label reach at least 7.8 HSPF2 for split systems (7.2 for single-package units).
  • The ENERGY STAR Cold Climate designation asks for more: at least 8.1 HSPF2 for ducted split systems (8.5 for non-ducted), plus verified low-temperature performance — at 5°F, a heating COP of at least 1.75 and at least 70% of the 47°F heating capacity.

For property and business owners

The same scores are used for the home-size heat pumps found in small offices, shops and apartments. Large rooftop units are rated in a different way, so these numbers do not apply to them.

If tenants pay the electricity bill, a better score lowers their bill. If the owner pays, it lowers the owner’s bill. For larger buildings, see our commercial page.

How we help you choose

We look at the building, the ducts, the heating it needs on a cold day and the backup heat you have. Then we compare models with the same kind of score, so the comparison is fair. The quote lists parts and labor separately.

Sources

Need help with this?

Heat Pump Service

Our heat pump service page describes the work and how to book it. We assess the system, explain what we found and provide a written quote for approval before work begins.

Before you call

Safe checks, and what needs a professional

Leave these to a professional

  • Smoke, flames or signs of a fire: leave the building, stay out and call 911.
  • A gas smell: leave the building and call your gas provider first, then call us.
  • Water leaking around the equipment, or staining near a ceiling unit.
  • Ice on the coils, or an outdoor unit that runs without cooling.
  • A breaker that trips repeatedly whenever the system starts.

Safe checks you can do yourself

  • Check the thermostat: is it set to heat or cool, and is the set point where you expect?
  • Check the filter: a clogged filter limits airflow. Replace it if it is visibly dirty.
  • Check the power: look at the breaker and the equipment switch near the unit.
  • Check the airflow: hold a hand at a supply register and feel whether air is moving.
  • Check the outdoor unit: clear leaves and debris from around it.

How to read the two numbers here

The standard score is calculated for a moderate winter. Northern Illinois winters are colder, so read the numbers this way

  1. Step 1

    Compare region 4 with region 4.

    It is the standard published score, so most makers list it and the comparison is fair.

  2. Step 2

    Treat region 4 as a moderate-climate figure.

    In a colder winter here, a heat pump usually uses more electricity than the region 4 score suggests.

  3. Step 3

    If a region 5 figure is shown, compare it with region 5.

    It is an optional colder-climate figure some makers also publish, not the standard rating.

What matters more than the score here

In a cold climate, the score is only one part of the choice. Ask these questions too

  • Does it keep heating in real cold?

    Some heat pumps lose much of their power on very cold days. Cold-climate models keep most of it. The ENERGY STAR Cold Climate mark is a simple way to find them.

  • Is it the right size for the building?

    A heat pump that is too small runs its backup heat too often. One that is too big switches on and off and feels less comfortable.

  • What is the backup heat?

    Many buildings here keep a gas furnace as backup for the coldest days. Others use electric backup heat, which costs more to run.

  • Are the ducts in good shape?

    Leaky or undersized ducts waste the gain from a better score.

Common questions about heat pump ratings

Does a higher score make the house warmer?
No. The score is about how much electricity the heat pump uses. Warmth on a cold day depends on the size of the heat pump and how well it works in low temperatures.
What about SEER2?
SEER2 is the cooling score. HSPF2 is the heating score. In northern Illinois the heating score matters more, because the heating season is longer.
Who can help if I am choosing a new heat pump or fixing one I own?
See heating installation when you are choosing a new heat pump, or heat pump service for one you already own.

Heating and cooling service · Hillside IL

Heating and cooling service in Hillside IL

SquareHVAC repairs, replaces and maintains heating and cooling systems for homes and businesses in Hillside IL and the surrounding communities.

We inspect the equipment, explain what we find and provide a written quote with parts and labor listed separately. You decide if and when the work happens. Serving homeowners and businesses since 2009.

Request service Call (708) 673-5633
  • Family-owned business
  • Licensed, bonded and insured
  • Serving since 2009