As we are being pushed to use more efficient methods to light or heat our rooms, Tom Murphy asked the simple question of “what is the most efficient method to boil water?”
The full article can be found at Burning Desire for Efficiency.
The summary of the results was:
- Boiling water on gas stove, full blast, no lid
- Boiling water in same pot, smaller burner, with lid
- Boiling water in kettle on small gas burner
- Heating water in microwave oven
43% (adjusted to 15%)
- Boiling water in electric kettle
50–80% (adjusted to 18–28%)
- Gas hot water heater, including tank loss
- Gas got water heater, without tank loss
The adjusted values for the electric devices take into account the inefficiencies of producing electricity by burning coal and then distributing it.
He then even analysed the efficiencies of cooking a pizza in his gas oven and discovered how inefficient the process was.
His conclusions are
- that we are hopeless at efficiently heating water,
- solutions for the problem are not necessarily cost effective because we don’t use a huge amount of hot water in the house
- changes in behaviour are much more likely to be effective. So don’t over fill the kettle and have shorter showers.
For anyone who would like to reproduce these types of experiments, I would recommend the Logtag with probe.