Our model house, in numbers
The house in our videos is a model, not a real family. These are the numbers it uses, where each one comes from, and which ones are examples you should change to your own.
The heat pump against gas boiler example
| Number | Value | Label | Source or note |
|---|---|---|---|
| Where | London, Ofgem region C | ◆ Chosen | One region as an example. Your region's prices differ. |
| Gas used a year | 9,500 kWh | ✓ Documented | Ofgem, review of typical domestic consumption values, decision of May 2026, medium use from 1 July 2026 (Great Britain). We treat all of it as heating and hot water. |
| Gas boiler efficiency | 90% | ◆ Chosen | An example. Real boilers vary; the calculator lets you change it. |
| Heat pump SPF | 2.78 | ✓ Documented | Median seasonal performance in the Electrification of Heat project, Project Summary Report, December 2024, page 31. The middle half of homes ranged from 2.55 to 3.05. |
| Electricity price | 26.60p a kWh | ✓ Documented | Ofgem price cap tables, London, direct debit, single rate, 1 October to 31 December 2026. |
| Gas price | 8.15p a kWh | ✓ Documented | Same tables. Includes 5% VAT. |
| Standing charges | 42.92p and 30.20p a day | ✓ Documented | Same tables, electricity and gas. They do not change the running-cost difference unless gas is disconnected. |
| Cosy tariff rates | 14.12p, 28.80p, 43.19p | ✓ Documented | Octopus Energy public price data, product COSY-22-12-08, region C, read on 12 November 2026. Cheap, day and peak rates. |
| How the heat pump's power is split on Cosy | 60% cheap, 40% day, 0% peak | ◆ Chosen | An example of a home that moves its heating to cheap hours. Yours may differ. |
| Cosy season and terms | Not checked | ? Unknown | Cheap hours and terms can change by season and by supplier. Check the current terms. |
| Cost of disconnecting gas | Not included | ? Unknown | Only matters if you switch the gas off entirely. |
The home battery example
| Number | Value | Label | Source or note |
|---|---|---|---|
| Quote | £6,800 | ◆ Chosen | An example, not a market price. |
| Battery size | 10 kWh | ◆ Chosen | An example. |
| Tariff and use | Economy 7, 4,200 kWh a year | ◆ Chosen | An example of a home with a night rate. |
| Round-trip efficiency | 90% | ◆ Chosen | Energy you get back for each unit you put in. Your battery's datasheet says what it is. |
| Single-rate electricity price | 26.32p a kWh | ? Unknown | Not yet re-checked against Ofgem's page. See the calculator's own source list. |
| Economy 7 night and day rates | 14.19p and 32.65p | ? Unknown | Not yet checked against a primary source. |
Each calculator also has its own list of what is fact, what is chosen and what is unknown, under "What is fact, what is chosen, what is unknown". How to read the labels, and what the calculators leave out.
General information, not financial, tax or electrical advice. Prices change; these were read on the dates shown.