In this column, staff at the Center for EcoTechnology offer advice on easy ways for people — and businesses — to introduce green changes in their daily lives.
Q: Winter has finally arrived ... with a vengeance. Are there any neat technologies I can use to stay warm while saving money and reducing my carbon footprint?
A: There sure are!
Heat pumps are devices that use electricity to move heat from areas of warm to areas of cold. Air source heat pumps (ASHP), in particular, are capable of exchanging heat with the air outside your home, taking heat out of the cold air and bringing it into your home in the heating season and moving heat out of your home in the cooling season.
According to the Northeast Energy Efficiency Partnerships, replacing electric baseboard heating with an ASHP reduces heating costs by approximately 3,000kWh every year. Take a look at your electric bill to see how that savings would impact you.
Q: Wait, what do you mean it takes heat from the cold air? There's no heat for it to take.
A: It seems too good to be true, but it's not! Heat naturally moves from areas of warm to areas of cold until those areas become approximately the same temperature.
A split-system ASHP has a warming side and a cooling side, using a set of coils both inside and outside your home. On a cold day, a refrigerant liquid (similar to what you'd find in a window air conditioner) is pumped through the coils outside of your home. The refrigerant is colder than the outside air, so it takes heat from the cold air, causing it to heat up and evaporate.
The now-warmer refrigerant is pumped back inside to a compressor, which increases the temperature (increasing the pressure on a liquid or gas causes its temperature to increase also). This pressurized vapor flows through the indoor set of coils, where it gives off that heat as it is condensed back into a liquid. The air heated by the condensing vapor is blown into your home through duct work, while the refrigerant (now condensed back to a liquid) is pumped back outside to acquire more heat.
Q: Okay, but I don't have any ducts in my home- I heat with water/steam/electric. Now what?
A: That's okay. Ductless mini-split heat pumps are more compact ASHPs that do not require a duct system. They simply use a blower motor to push the warm air into your living space. Because they are smaller, they do not produce as much heat as a full-sized ASHP, which makes them better suited to heating or cooling a room or two, much like an electric baseboard or window air conditioner.
You can read more about heat pumps at the Department of Energy's website.