25 degrees of separation

Recently there has been some campaigns about running your air-conditioner at 25 degrees Celsius for energy efficiency and to save the environment.

Let me put it this way. It doesn't work for everyone. For someone like me who doesn't use the air-con at home, insisting to maintain a temperature of 25°C by means such as keeping your fridge door open or otherwise, will result in higher usage/wastage of electricity. I think the 25 shouldn't be kept as a rule but rather a general guideline. It will be equally stupid to keep freezer at 25°C.

I read a brochure from Hong Kong's Electrical and Mechanical Services Department and they say that if you raise the temperature from 22.5°C to 25.5°C, it can save 9% of energy. I know I studied thermodynamics, but don't ask me to verify. But if you raise it to 31°C, won't you save even more energy?

There is a term called "thermal comfort". In simple terms it means whether a person feels warm or cold, and this is determined by factors such as air temperature, air speed, humidity, human activity, clothing insulation, etc.[Cornell University Ergonomics Web] According to the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Standard 55-2004, different humidity will have different temperature range for comfort. For example, if the relative humidity is 30%, the acceptable operative temperature range would be 24.5-28°C. It would be 23-25.5°C for 60% relative humidity. Sounds logical.

Whatever it is, I think our human body is the best thermometer. One look and you know if the girl is hot or not.