Estimate yearly heating energy and money saved versus a leaky home on the same floor area.
| kWh saved / year | – |
| Money / year | – |
Use this calculator when you are comparing a retrofit or a new build against a Passivhaus heating number and want kWh and money on the same floor area.
The calculation is: kWh saved = (ordinary kWh/m²·year − passive kWh/m²·year) × floor area. Money is that kWh × the price you type. Floor area can be entered in square metres (m²) or square feet (ft²); it is converted to m² before the formula. Passive-house heating is often quoted near 15 kWh/m²·year versus a leaky 100. This is space heat only, not the whole bill or the carbon locked in the walls.
Floor area: Heated floor area you actually heat, in m² or ft², e.g. 120 m².
Standard kWh / m²·year: Heating demand of the ordinary house. A leaky home is often around 100.
Passive-house kWh / m²·year: Passive-house heating target. The classic figure is 15.
Price / kWh: What you pay per kWh of heat (gas or electricity), e.g. 0.25.
kWh saved / year: Extra heating energy the ordinary house would use.
Money / year: That energy times your heat price.
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