Heat loss intensity: — BTU/hr per sq ft | Est. annual heating cost: — | Total potential savings: —/yr
- Walls—
- Windows—
- Roof / ceiling—
- Doors—
- Floor—
- Air infiltration—
Savings Opportunities
Percent shows the reduction in total heat loss from each upgrade; dollars are the estimated annual heating savings.
Analysis Summary
| Design heat loss | — |
| Recommended furnace | — |
| Heat pump size | — |
| Biggest loss | — |
| Annual heating cost | — |
Typical Heat Loss by Home Size
| Home size | Typical design heat loss |
|---|---|
| 1,000 sq ft | 20,000 – 40,000 BTU/hr |
| 1,500 sq ft | 30,000 – 60,000 BTU/hr |
| 2,000 sq ft | 40,000 – 80,000 BTU/hr |
| 2,500 sq ft | 50,000 – 100,000 BTU/hr |
Ranges span poor to good construction and mild to cold climates.
Why Is My House Cold, and What Size Heater Do I Need?
Heat loss is the rate at which your home leaks warmth to the outdoors on a cold day, measured in BTU per hour. By itself that number is not very useful, so this analyzer goes further: it breaks the loss down by walls, windows, roof, doors, floor, and air leakage so you can see where your house is cold, then recommends the furnace and heat pump size that matches the load and estimates what sealing and insulating could save you each year. Enter your building type, construction quality, climate zone, and dimensions, and the calculator does the rest.
What Is a BTU?
A BTU, or British Thermal Unit, is the heat needed to raise one pound of water by one degree Fahrenheit. Heating equipment is rated in BTU per hour, the rate it can add heat. If your home loses 36,000 BTU per hour on the coldest design day, your heating system must be able to replace at least that much to keep you comfortable. Divide BTU per hour by 12,000 to get tons, the unit used for heat pumps and air conditioners.
Heat Loss vs Heat Load
People mix these up constantly. Heat loss is specifically the warmth escaping in winter through the building envelope and air leaks. Heat load, or heating load, is the broader demand your equipment must meet, which for most homes is essentially the heat loss at the design temperature. Cooling load is the summer equivalent and includes solar gain and internal heat, so it is calculated differently. For sizing a furnace or a heat pump in heating mode, the design heat loss is the number you want.
Air Leakage: The Hidden Loss
Many homes lose more heat through air infiltration than through their walls. Every gap around windows, doors, outlets, attic hatches, and rim joists lets warm air escape and cold air pour in, and that air has to be reheated continuously. Because air sealing is cheap compared to new windows or wall insulation, it is usually the highest-return improvement you can make. The breakdown above shows how much of your loss is infiltration, and the savings panel estimates what tightening the house would save.
Heat Pump Compatibility
Heat pumps move heat instead of burning fuel and can heat efficiently even in cold climates, but their output drops as the outdoor temperature falls. The key is sizing the heat pump to deliver your design heat loss at your design temperature; in very cold zones that means a cold-climate model plus backup heat for the worst days. The analyzer suggests a heat pump size and flags whether your climate calls for backup.