Insulation Savings Calculator
Find out how much you save on heating bills — and how fast your insulation pays for itself.
Calculating material first? Insulation Material Calculator → | Heat Loss Calculator →
Project
Your Project
Results
Estimates based on typical U-value improvements. Actual savings vary by climate, heating system and building construction.
Common questions about insulation savings
How much do you save by insulating your loft?+
Insulating an uninsulated 60 m² loft to 200 mm (good level) typically saves around €200–€350 per year on heating bills at average European energy prices. The payback period is usually 2–5 years, making loft insulation one of the best-value home improvements available.
How much do you save by insulating external walls?+
Insulating 80 m² of uninsulated external walls to a good standard (U-value from 1.6 to 0.18 W/m²K) can save €400–€700 per year. Wall insulation costs more to install, so payback periods are typically 10–20 years — though comfort improvements and property value gains add to the overall benefit.
How long does insulation take to pay for itself?+
Payback = installation cost ÷ annual savings. Loft insulation: 2–5 years. Cavity wall fill: 4–8 years. External wall insulation: 15–25 years. Floor insulation: 8–15 years. Government grants and subsidies can halve these figures — check what's available in your country.
Which insulation saves the most money?+
Roof/loft insulation gives the best return — heat rises, uninsulated roofs have very high U-values (~2.3 W/m²K) and installation is relatively cheap. After the roof, cavity wall fill is usually next. Floor insulation is worth doing during a renovation but rarely cost-effective as a standalone project.
Is it worth insulating before getting a heat pump?+
Yes — improving insulation before installing a heat pump reduces the required system size, lowers running costs and improves efficiency. A heat pump in a poorly insulated home has to work harder and cycles on and off more, reducing its COP. Insulating first means you may need a 5 kW heat pump instead of a 10 kW, saving thousands on installation and hundreds per year on running costs.
How insulation savings are calculated
The method
Heat loss through a building element is calculated using U-values — a measure of how much heat passes through one square metre per degree of temperature difference per hour (W/m²K). Better insulation means a lower U-value and less heat escaping.
Annual energy saved = area × (U-value before − U-value after) × heating degree days × hours per day
Typical U-values by insulation level
Uninsulated wall: ~1.6 W/m²K. Standard: ~0.35. Good: ~0.18. Excellent: ~0.13. Passivhaus: ~0.10.
What affects real savings?
Climate (heating degree days), your heating system efficiency, thermostat behaviour and airtightness all affect actual savings. This calculator uses typical European figures — results in colder climates will be higher.