Will a heat pump keep you warm here?
Enter your town or ZIP and a few facts about your home. We draw how much heat it loses against what a cold-climate heat pump makes, using real hourly weather for your area and the altitude you live at.
Will it keep you warm at −10°F, at 5,870 feet?
Example for a 1,850 sq ft typical home in Lakewood. Enter yours above.
Yes, with backup for the coldest hours. A 2.5-ton cold-climate heat pump carries the home down to about 3°F to 11°F. Below that, backup heat covers the gap, about 155 hours a year at most.
- Design temperature here is about 5°F: only the coldest 1% of hours in a typical year are colder, about 77 hours. Jefferson County’s published value is 5°F; the Centennial Airport record gives 6.1°F. We use the colder.
- At −10°F the heat pump still supplies about 57 to 71% of the heat. The rest comes from backup, or your furnace if you keep it as dual fuel. It gets that cold here about 3 hours a year.
- Air at 5,870 feet is about 20% thinner than at sea level. Output drops by less than that, but how much is the manufacturer’s number: ask your installer for their altitude table. The dashed line is the worst case.
- ENERGY STAR cold-climate models must still heat efficiently at 5°F (COP 1.75 or better) and keep at least 70% of their rated output there.
- Balance point
- 3°F to 11°Fworst case to rated
- Hours a year below it
- 59 to 156NOAA hourly, 2011 to 2024
- Heat from the heat pump
- 99 to 100%of the year’s heating
- Backup heat
- 5 kW stripor your furnace as dual fuel
About 0.9 kW of backup covers the gap at the design temperature, so a 5 kW heat strip, or your existing furnace kept as dual fuel. Weather from Centennial Airport (5,870 ft), 16.6 miles from the center of ZIP 80226.
The chart as a table
| Outdoor | Heat loss | Heat pump, rated | At altitude, worst case |
|---|---|---|---|
| 40°F | 8,325 | 28,500 | 22,915 |
| 17°Frating point | 15,984 | 23,571 | 18,952 |
| 5°Frating point | 19,980 | 21,000 | 16,885 |
| −10°Fcold night | 24,975 | 17,786 | 14,300 |
| −13°Flowest operating temperature | 25,974 | 17,143 | 13,783 |
Btu per hour. “Off” means below the heat pump’s lowest operating temperature.
Four questions for your installer
A good proposal answers these in writing. They come from our guide to heat pumps in Colorado.
Was there a load calculation?
A room-by-room Manual J, with the altitude correction. Colorado’s heat pump tax credit already requires a heat load calculation for 2026 installs.
What does it make at 5°F?
Capacity at 5°F and at your design temperature, from the extended performance data, not the brochure headline.
Where is the balance point?
And what backup did they size for the hours below it: heat strips, or your furnace kept as dual fuel.
Which altitude table?
Ratings are measured at sea level. Ask which correction they applied for your elevation, and where it came from.
More detail: Will a heat pump keep me warm at −10°F and at altitude?
How this works
What this assumes
- Heat loss: 0.18 Btu/h per °F per square foot for a typical home, zero at 65°F outdoors.
- Heat pump output: a 2.5-ton cold-climate unit that just meets the ENERGY STAR floor (70% of rated output at 5°F). Many current models do better.
- The heat pump stops heating below -13°F (its lowest operating temperature).
- Design temperature: the colder of the published county value (5°F) and the weather station's own 99% value (6.1°F).
- Altitude: 5,870 ft (the weather station; enter yours if it differs). The lower output line scales capacity by air density, the worst case.
- Hours are a yearly average of NOAA hourly readings at the weather station.
What it cannot tell you
- This is a screening estimate, not a load calculation. A room-by-room Manual J with altitude correction decides the size.
- Real heat loss depends on windows, air leakage, ducts and how you set the thermostat.
- Defrost cycles and the manufacturer's own altitude correction are not modelled; ask your installer for the altitude table they used.
- The weather station is 16.6 miles from your ZIP's center. Hills and valleys can be colder.
Sources
- ENERGY STAR Certified Homes, Design Temperature Limit Reference Guide, Exhibit 1, Colorado (pages 13 to 15, revised 09/01/2018) (opens in a new tab)
- NOAA ISD-Lite hourly observations (opens in a new tab)
- Unico Technical Note 103, High Altitude Applications, Table 2 (air density ratio by altitude) (opens in a new tab)
- ENERGY STAR cold climate heat pump criteria (via DOE FEMP) (opens in a new tab)
- EIA Residential Energy Consumption Survey 2020 (opens in a new tab)
Want this done properly for your house?
Your plan pairs a load calculation and a cold-climate model with the rebates you can stack. Free, and no obligation.