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There are many ways to reduce your impact, but today I’m going to talk about heating your home or apartment or living space.

The amount of power required depends on several factors. Most important are the temperature difference between inside and outside, the leakiness of the house, and the efficiency of the heater. The equation looks like this:

power = temperature difference * leakiness / heater efficiency

Clearly, there are three ways to reduce the needed power. Reduce the temperature difference, reduce the leakiness, and increase the efficiency.

Temperature difference

The temperature difference depends on the temperature set by the thermostat and the temperature outside. You can’t control the weather, but you can change your thermostat setting. The figure below shows a month of temperatures and thermostat settings. If the setting is 60 deg F, the green area is the indicator of power needed to heat the house. If the setting is 70 deg F, the green and blue areas are needed (a 58% increase).

Corvallis, OR high and low temperatures for January 2015 (data from NOAA)

Corvallis, OR high and low temperatures for January 2015 (data from NOAA)

The easiest way to reduce your needed power is to put on a sweatshirt and lower the thermostat. Maybe 60 deg F (saving 37%) leaves you too cold; you can still save 19% by reducing the temperature to 65 deg F. Remember, the point is to keep the room warm for humans. If you’re at work, turn down the home thermostat. Programmable thermostats start at just $25 and some utilities even offer rebates to make them free. Alternatively, make sure your workplace doesn’t heat itself when no one is there.

Leakiness

This is the rate that energy escapes the house through walls and windows. It depends on the temperature difference too. There are many programs (like this one in Oregon) that can evaluate your house for leakiness. Adding insulation can save up to 40% of your heating costs by reducing heat loss.

Heater efficiency

Let’s say you have a natural gas powered heater. The gas is combusted and the heat is exchanged to the air in your house. Some heat is lost in the exhaust and some energy is needed to blow the air around your house. Maybe 90% of the energy released from the natural gas is heating your home.

If you have an electric heater, 100% of the energy is released to the house. However, this is only half the story. Remember, some forms of energy are more valuable. If natural gas was used to make the electricity, maybe 40% of the gas’ thermal energy was converted to electricity. So if your electricity mix is heavily fossil fuel powered, it’s more efficient overall to have a natural gas heating system in your house.

However, heat pumps offer a much better “efficiency”. In a heat pump, electricity is used to move heat from outside air or the ground into the house. Heat pumps can be around 300% to 400% “efficient.” Many people would avoid the use of the word efficiency here, but our equation still works. This works since electric energy is more useful than thermal energy. So if you switch to a heat pump, even coal fired electricity is better than a home fossil fuel heater.

Reduce your footprint

The best options for reducing your heating consumption are to turn the thermostat down, stop leaks from your house, and switch to a heat pump. Often there are incentives and/or groups to help you increase energy efficiency in the home. You can save money and save energy.

Further reading: Sustainable Energy: Without the Hot Air by David McKay (Ch 21 Smarter heating)

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