How the index is calculated

The WarmGuide Price of a Warm Home Index combines two official government datasets to produce a city-level annual heating cost estimate that is both accurate and fully sourced.

The base energy cost for each city uses Ofgem’s Final Levelised Cap Rates Model (Annex 9) for Q4 2026 — the same data used to set the maximum charges for the October 2026 price cap. This gives us the official dual fuel benchmark annual bill for each of the 14 Ofgem Charge Restriction Regions.

We then apply a city-level gas consumption adjustment using the Department for Energy Security and Net Zero (DESNZ) Subnational Gas Consumption Statistics 2024, which publish mean domestic gas consumption in kWh per meter for every local authority in Great Britain. Where a city’s actual mean consumption differs from Ofgem’s Typical Domestic Consumption Value of 9,500 kWh, we adjust the gas component of the bill up or down using the regional gas unit rate from Annex 9.

Electricity is held at the Ofgem regional benchmark (2,500 kWh TDCV) because city-level electricity consumption data was not available at publication. All figures are for Direct Debit customers on a single-rate electricity meter and include 5% VAT on gas; electricity is VAT-free under the government’s temporary relief running from 1 October 2026 to 31 March 2027. This index will be updated quarterly when Ofgem publishes new cap rates.