“Progressive” thermostats to save energy

Sitting in my cold, air-conditioned classroom the last week, while it was 85-95ºF outside, a design for a new thermostat came to me. Currently, thermostats cool (or heat) a building to a desired temperature. My new design would create a floating target temperature, that moves up and down as the outside temperature changes. The goal would be to target a temperature that is half-way between the “comfort zone” (generally 65-72ºF) and the outside temperature.

For example, if the temperature outside is 92ºF and the comfort zone max is 72ºF, the air conditioning would be set to 82ºF.

An example of a cold day: If the temperature outside is 45ºF, and the comfort zone minimum is 65ºF, the heater would be set to 55ºF.

Progressive vs traditional thermostat
Progressive vs traditional thermostat

What’s the advantage?

Physics principles state that the greater the temperature difference between two bodies, the faster the heat is transferred between them. Thus, if the outside temperature is 92ºF, it takes less energy to cool a house from 92ºF to 82ºF than to cool it the next 10ºF, from 82ºF to 72ºF. And since hotter and colder days place higher demands out our electrical grid (especially hot days), these are the days where we need to save energy the most.

Other adjustments/design alternatives

  • This new design could allow for adjusting the percent difference for hot and cold days individually. For example, if a person can handle heat better than cold, s/he might change hot days to only 25% of the way from the outside temperature to the comfort zone (using the previous example, cooling the house to 87ºF), but on cold days s/he would set it to 75% (the example above heat to 60ºF).
  • The thermostat could easily be designed to have a maximum hot temperature allowed (e.g. never over 82ºF) and/or a minimum cold temperature (e.g. 50ºF). This would be useful in extremely hot or cold climates.

With wireless technology as simple and inexpensive as it is these days, it would be easy to place the outside temperature sensor in an appropriate location, not necessarily right outside the thermostat.


Please leave your comments below. I’d love to hear what others feel about this idea.

Great “raw” video footage from typhoon in China

The video below is just “raw” footage from CBS News. There is no narration, just a collection of images. I really enjoy this format, you can focus on the images and not on what the newscaster is saying. Powerful.

Typhoon Slams China

Sun Aug 09 11:26:08 PDT 2009

“CBS News RAW”: Millions evacuated the area after typhoon Morakot slammed into China’s east coast. It was the island’s worst flooding in 50 years and left dozens missing and feared dead.

Watch CBS Videos Online