I did the @SarahH Sarah Hanson test which I find v.interesting. Details below
Test conditions
| Parameter | Value |
|---|---|
| Location | ***, UK |
| Test Date | 18-19 March 2025 |
| Time Period | 8 PM – 6 AM (10 hours) |
| Heating | Off during test |
| Outdoor Temperature | 3.55°C (average) |
| Indoor Temperature Start | 21.2°C |
| Indoor Temperature End | 16.4°C |
| Heat Pump Output | 4kw |
| House Type | Well-insulated with radiators |
Findings & Observations
| Metric | Value |
|---|---|
| Temperature Drop (°C) | 4.8 |
| Cooling Rate (°C/hour) | 0.48 |
| Surveyed Heat Loss of house | 2.254 kW |
| Estimate heat loss in the period | 1.74 kW |
| Average heat loss in the period | 2 kW |
| c.Thermal Inertia | 9,000 kJ/K |