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Insulation heat saving Calculator
Estimate fabric heat loss avoided by improving a U-value. This free insulation heat saving calculator shows the calculation and its assumptions so you can compare your own figures.
Your results
Estimate fabric heat loss avoided by improving a U-value.
Calculated outcomes
- Fuel Saving KWh
- 8,075.29 kWh
- Simple Payback Years
- 6.19 years
Assumptions and estimates
- Method: Annual heat saving = area × U-value improvement × degree-days × 24 ÷ 1,000. Fuel saving divides by efficiency.
- Degree-days must match the location and base temperature. Ignores thermal bridges, solar gains, occupancy and ventilation. A worse U-value produces a negative saving.
Useful next steps
- Check the payback period against how long you will keep the vehicle.
- Use Compare options to test an alternative side by side.
- Copy, print or download a record of this calculation when you need one.
Reports open your email app addressed to s@s1.ie with the public page address only. Your inputs are never added.
How the insulation heat saving calculation works
Annual heat saving = area × U-value improvement × degree-days × 24 ÷ 1,000. Fuel saving divides by efficiency.
Degree-days must match the location and base temperature. Ignores thermal bridges, solar gains, occupancy and ventilation. A worse U-value produces a negative saving.
Using this calculator
- Enter your own figures in the labelled inputs. Keep the currencies, units and time periods consistent.
- Choose any applicable rate profile, pattern or assumption shown for this tool. Open additional inputs when relevant.
- Review annual saving and heat saving kwh, then read the stated assumptions and eligibility conditions before using the result.
Worked example
This is a static example using illustrative inputs, not facts about you or today’s date. The displayed eligibility selections and assumptions apply only to this example.
See example inputs
- Insulated area (m²)
- 100
- Existing U-value (W/m²K)
- 1.5
- Improved U-value (W/m²K)
- 0.2
- Annual heating degree-days (K·days)
- 2200
- Heating efficiency (%)
- 85
- Fuel price (€/input kWh)
- 0.1
- Project cost (€)
- 5000
- Annual Saving
- €807.53
- Heat Saving KWh
- 6,864 kWh