Understanding your boiler's running costs helps you budget accurately and identify when something's wrong. Here are realistic gas consumption figures for different home types.
Average gas consumption by property type
| Property | Bedrooms | Annual Gas Use | Estimated Cost |
|---|---|---|---|
| Flat | 1–2 | 8,000–11,000 kWh | £560–£770 |
| Terraced house | 2–3 | 11,000–14,000 kWh | £770–£980 |
| Semi-detached | 3 | 14,000–17,000 kWh | £980–£1,190 |
| Detached house | 4–5 | 17,000–22,000 kWh | £1,190–£1,540 |
Based on current gas price of ~7p/kWh. Actual costs vary with insulation, occupancy, and usage habits.
What affects running costs most
Insulation: A poorly insulated home can cost 40–50% more to heat than a well-insulated equivalent. Loft insulation and cavity wall insulation are the most cost-effective improvements.
Thermostat settings: Every 1°C reduction in room temperature saves around 6% on heating costs.
Boiler efficiency: Upgrading from a 78% efficient old boiler to a 92% new one reduces gas consumption by ~15% — around £140/year on an average semi-detached.
Smart thermostat savings
A well-configured smart thermostat typically reduces annual gas consumption by 15–20%, saving £150–£280/year for an average semi-detached — and typically paying for itself within 12–18 months.