Heating load in Sierra Vista
A home in Sierra Vista has to be heated against a design temperature of −3.5 °C. That figure is measured, not modelled: it is the 1st percentile of daily minimum temperature over 24 years at Sierra Vista Municipal-Libby Aaf Airport, 5 km away.
Design temperature
−3.5 °C
Heating degree days
683
Coldest month
Jan
Coldest night on record
−16.0 °C
Coldest station in range
−8.5 °C
How many kilowatts
Heating power needed at the design temperature, in kilowatts, for a detached house. Pick the row that matches the building.
| Construction | Detached | Semi-detached | Terraced | Top-floor flat | Mid-floor flat | Ground-floor flat |
|---|---|---|---|---|---|---|
| Uninsulated, single glazed | 15.1 kW | 13.3 kW | 11.8 kW | 12.9 kW | 6.3 kW | 7.7 kW |
| Unfilled cavity, early double glazing | 10.3 kW | 8.8 kW | 7.7 kW | 7.5 kW | 4.5 kW | 5.7 kW |
| Insulated to 1980s standards | 5.9 kW | 5.3 kW | 4.8 kW | 4.5 kW | 3.2 kW | 4.1 kW |
| Modern, roughly 1995-2010 | 3.6 kW | 3.3 kW | 3.0 kW | 2.9 kW | 2.2 kW | 2.7 kW |
| Current building regulations | 2.8 kW | 2.5 kW | 2.3 kW | 2.3 kW | 1.7 kW | 2.1 kW |
| Passive house | 1.6 kW | 1.5 kW | 1.3 kW | 1.3 kW | 0.9 kW | 1.2 kW |
Where the heat goes
For a 120 m2 detached house of this construction, at the design temperature.
| Element | W | Share |
|---|---|---|
| Walls | 1,931 | 33% |
| Roof | 564 | 10% |
| Ground floor | 381 | 7% |
| Windows | 1,100 | 19% |
| Thermal bridges | 323 | 6% |
| Ventilation and draughts | 1,558 | 27% |
| Heating load | 5,856 | 5.9 kW |
Calculate it for your own home
The climate half of this is measured. The building half is yours to supply.
Monthly mean temperature
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| °C | 9.2 | 11.1 | 14.4 | 17.9 | 22.4 | 27.7 | 26.6 | 25.6 | 23.9 | 19.7 | 14.2 | 9.3 |
Where these numbers come from
- Measured: the design temperature, the degree days and the monthly means. All of it from one station, Sierra Vista Municipal-Libby Aaf Airport, over 24 complete years.
- Assumed: everything about the building. The U-values are typical published figures for each construction era, not a survey of your house. Two houses of the same age and size can differ by a factor of two.
- No credit is taken for sunshine or for the heat given off by people and appliances. That is the EN 12831 convention, because the design condition is a still, dark night.
- This is space heating only. Domestic hot water is a separate load.
- This is a calculation, not a survey. Before spending money, have the building assessed.