- Heating a House
- The optimum temperature range for a lightly clothed person is 15–20°C; clothing should prevent both heat loss and overheating, depending on climate.
|
Heat Transfer / Device |
Key Point |
|
Radiation |
Heat travels in a straight line without necessarily heating the medium; intensity ∝ 1/distance² |
|
Conduction |
Heat moves between bodies in direct contact; conductors transmit well, insulators (e.g. asbestos) poorly |
|
Convection |
Heated liquid/gas rises (becomes lighter) as cooler fluid sinks |
|
Open fires |
Burn smokeless fuel/coal; only 20–30% efficient |
|
Stoves |
Open stoves ~50% efficient; closed stoves up to 70% |
|
Oil heaters |
Burn kerosene/paraffin; movable, but can smell oily |
|
Electric heaters |
Heat a tungsten coil; storage heaters release heat gradually |
|
Gas fire / Air conditioner |
Gas fire burns methane/propane/butane to radiate heat; A/C heats and regulates incoming air |
Preventing Heat Loss
- Keep doors closed; use double-glazed windows; paint the roof a dull colour (black/grey); put foam insulation in cavity walls; insulate the roof space (loft).