Find out if reducing the temperature while you're away actually saves energy - and exactly how much.
Results are estimates based on a simplified physical model.
How it works
It compares energy consumption between two scenarios: (a) thermostat stays constant, (b) thermostat is lowered by Y degrees for X hours. Uses an exponential cooling model and linear recovery.
Building type
Thermal properties are calculated automatically - you can adjust them afterwards.
Parameters
Parameters
Parameters
Parameters
Engineer mode
Engineer mode
The UA coefficient (W/K) expresses how many Watts a building loses for each degree Celsius of temperature difference between inside and outside. It includes walls, windows, roof, floor, and ventilation.
Thermal mass C (Wh/K) measures how much energy a building stores. High thermal mass (concrete, brick) means slower cooling - but also slower heating.
The time constant τ = C/UA shows how quickly a building cools down. A large τ (>15h) means slow cooling → small benefit from setback.
Multiply your home's floor area (m²) by the coefficient below:
| Building condition | W/K per m² |
|---|---|
| Very poor (old, bad windows) | 4.0 – 5.0 |
| Uninsulated, typical | 3.0 – 4.0 |
| Moderate (double glazing) | 2.0 – 3.0 |
| Insulated | 1.0 – 2.0 |
| Very good / passive | 0.5 – 1.0 |
E.g. 85m² apartment with double glazing → 85 × 2.5 ≈ 210 W/K
Contact us for an energy assessment of your home and customized savings recommendations.
mail Contact UsThis calculator provides indicative estimates based on a simplified exponential cooling model. It is not an official energy study. Actual savings depend on many factors (insulation, airtightness, climate conditions, user behavior). See Terms of Service
