Deliverable 02 · Real-bill simulator · Ofgem Q4 2026 price cap

What does one degree actually cost you?

Same calculator BeSMART runs at the demo wall on Day 3 — built on live Ofgem unit rates and standing charges. Move the dial, watch the bill move.

Flat size55 m²

Studio4-bed house

Occupants2

Target temperature21°C

15°C · cold19°C · WHO24°C · tropical

Heating

Insulation

Pre-1980 Victorian conversion = poor. Modern flat with double glazing = average. Retrofit + EPC B = good.

Your estimated annual energy bill

£1,488

At 21°C · 55 m² · 2 occupants · gas · average insulation

£53

The cost of every single degree above 20°C, every year.

£0

Saved versus a 21°C household — that’s 0% off your bill.

779 kg

CO₂e from your heating alone this year (UK grid factors, 2024).

The three WHO/UK Health Security benchmarks

18°C — UKHSA minimum

£1,330 / year

+£158 above this benchmark.

The threshold below which the UK Health Security Agency warns of measurable health risk for vulnerable occupants.

19°C — WHO recommended

£1,383 / year

+£105 above this benchmark.

The World Health Organization’s recommended living-room temperature for healthy adults — and the BeSMART default.

Methodology: degree-day model with 0.085 kWh/m²/°C/day over a 182-day heating season, modified by an insulation factor (0.72 – 1.35). Ofgem unit rate 0.0617 £/kWh (gas), 0.2461 £/kWh (electric). Illustrative; your in-app BeSMART model uses your smart-meter half-hourly data.