Heating load in Boston
A home in Boston has to be heated against a design temperature of −14.4 °C. That figure is measured, not modelled: it is the 1st percentile of daily minimum temperature over 30 years at Gen E L Logan International Airport, 4 km away.
Design temperature
−14.4 °C
Heating degree days
2,376
Coldest month
Jan
Coldest night on record
−24.4 °C
Coldest station in range
−18.3 °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 | 22.2 kW | 19.4 kW | 17.3 kW | 18.9 kW | 9.2 kW | 11.3 kW |
| Unfilled cavity, early double glazing | 15.0 kW | 12.9 kW | 11.3 kW | 11.0 kW | 6.7 kW | 8.3 kW |
| Insulated to 1980s standards | 8.6 kW | 7.7 kW | 7.0 kW | 6.6 kW | 4.7 kW | 6.1 kW |
| Modern, roughly 1995-2010 | 5.3 kW | 4.8 kW | 4.4 kW | 4.3 kW | 3.2 kW | 3.9 kW |
| Current building regulations | 4.0 kW | 3.7 kW | 3.4 kW | 3.3 kW | 2.5 kW | 3.0 kW |
| Passive house | 2.4 kW | 2.2 kW | 2.0 kW | 1.9 kW | 1.3 kW | 1.7 kW |
Where the heat goes
For a 120 m2 detached house of this construction, at the design temperature.
| Element | W | Share |
|---|---|---|
| Walls | 2,826 | 33% |
| Roof | 826 | 10% |
| Ground floor | 557 | 7% |
| Windows | 1,610 | 19% |
| Thermal bridges | 473 | 6% |
| Ventilation and draughts | 2,281 | 27% |
| Heating load | 8,572 | 8.6 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 | −0.9 | 0.1 | 3.4 | 9.0 | 14.4 | 19.8 | 23.3 | 22.5 | 18.7 | 12.7 | 7.2 | 2.3 |
Where these numbers come from
- Measured: the design temperature, the degree days and the monthly means. All of it from one station, Gen E L Logan International Airport, over 30 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.