Heating load in Tauranga
A home in Tauranga has to be heated against a design temperature of 1.7 °C. That figure is measured, not modelled: it is the 1st percentile of daily minimum temperature over 30 years at Tauranga, 3 km away.
Design temperature
1.7 °C
Heating degree days
654
Coldest month
Jul
Coldest night on record
−1.0 °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 | 11.8 kW | 10.3 kW | 9.2 kW | 10.1 kW | 4.9 kW | 6.0 kW |
| Unfilled cavity, early double glazing | 8.0 kW | 6.9 kW | 6.0 kW | 5.8 kW | 3.5 kW | 4.4 kW |
| Insulated to 1980s standards | 4.6 kW | 4.1 kW | 3.7 kW | 3.5 kW | 2.5 kW | 3.2 kW |
| Modern, roughly 1995-2010 | 2.8 kW | 2.6 kW | 2.4 kW | 2.3 kW | 1.7 kW | 2.1 kW |
| Current building regulations | 2.1 kW | 2.0 kW | 1.8 kW | 1.8 kW | 1.3 kW | 1.6 kW |
| Passive house | 1.3 kW | 1.1 kW | 1.0 kW | 1.0 kW | 0.7 kW | 0.9 kW |
Where the heat goes
For a 120 m2 detached house of this construction, at the design temperature.
| Element | W | Share |
|---|---|---|
| Walls | 1,503 | 33% |
| Roof | 439 | 10% |
| Ground floor | 296 | 7% |
| Windows | 856 | 19% |
| Thermal bridges | 252 | 6% |
| Ventilation and draughts | 1,213 | 27% |
| Heating load | 4,560 | 4.6 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 | 19.9 | 20.2 | 18.5 | 15.9 | 13.6 | 11.2 | 10.5 | 11.1 | 12.7 | 14.3 | 16.1 | 18.3 |
Where these numbers come from
- Measured: the design temperature, the degree days and the monthly means. All of it from one station, Tauranga, 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.