Heating load in Joliet
A home in Joliet has to be heated against a design temperature of −20.4 °C. That figure is measured, not modelled: it is the 1st percentile of daily minimum temperature over 17 years at Joliet Regional Airport, 8 km away.
Design temperature
−20.4 °C
Heating degree days
2,632
Coldest month
Jan
Coldest night on record
−35.4 °C
Coldest station in range
−23.3 °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 | 26.0 kW | 22.8 kW | 20.3 kW | 22.2 kW | 10.8 kW | 13.3 kW |
| Unfilled cavity, early double glazing | 17.6 kW | 15.2 kW | 13.3 kW | 12.9 kW | 7.8 kW | 9.8 kW |
| Insulated to 1980s standards | 10.1 kW | 9.1 kW | 8.2 kW | 7.8 kW | 5.6 kW | 7.1 kW |
| Modern, roughly 1995-2010 | 6.2 kW | 5.6 kW | 5.2 kW | 5.0 kW | 3.8 kW | 4.6 kW |
| Current building regulations | 4.7 kW | 4.4 kW | 4.0 kW | 3.9 kW | 2.9 kW | 3.6 kW |
| Passive house | 2.8 kW | 2.5 kW | 2.3 kW | 2.2 kW | 1.5 kW | 2.0 kW |
Where the heat goes
For a 120 m2 detached house of this construction, at the design temperature.
| Element | W | Share |
|---|---|---|
| Walls | 3,319 | 33% |
| Roof | 970 | 10% |
| Ground floor | 654 | 7% |
| Windows | 1,891 | 19% |
| Thermal bridges | 555 | 6% |
| Ventilation and draughts | 2,679 | 27% |
| Heating load | 10,068 | 10.1 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 | −3.8 | −2.5 | 4.1 | 10.3 | 16.4 | 21.7 | 23.6 | 22.3 | 18.9 | 11.7 | 5.2 | −0.8 |
Where these numbers come from
- Measured: the design temperature, the degree days and the monthly means. All of it from one station, Joliet Regional Airport, over 17 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.