What Have we Done Already? (part 2: Adjusting the Heat)

According to wikipedia, a typical American home uses 44% of its energy for space heating. For our house approximately 50% of our gas usage goes towards space heating. That represents about $350 a year.

We have done a few things to save on our heating bill. First, we have installed a programmable thermostat, we have closed the heating vents in those rooms we don't use, and we close curtains/shutters at night to keep the heat in.

The programmable thermostat is a simple device that replaces your regular thermostat. It allows you to program when you want the house to be at particular temperatures.


The one we bought at the home megamart has different settings each day and 4 time blocks per day. During the day time block when we're at work, we have it set to 60F (~16C). In the evening around 6pm or so when we come home from work, it warms up to a more comfortable 67F (~19C). Later in the evening, we have it set to go back down to 62F (17C) for sleeping. Finally, we have it set to 67F (~19C) again for a half hour in the morning when Margaret gets up for work.

The second thing we have done is close the heating vents in those rooms we don't use, like the guest bedroom. This means those rooms become rather cold, but there is nothing in there that would have a problem with the temperature. (Yes, we do open them up again when people come to stay!) It also means that the heater doesn't have to work as hard to heat up the rest of the house to the set temperature.

Finally, we close the drapes/curtains/shutters at night. This helps keep the warmth in the house. A large percentage of the heat escapes the house via the windows rather than through the walls.

Together, these things have saved us roughly 8% or so on our gas bill in the winter months, and nothing in the summer of course. That represents about 30 therms of gas, 360 lbs of CO2, and $42 for all of 2007. The thermostat itself cost us $50, so it has paid for itself in 2 winters.

Things we still need to do:

• Insulate the ductwork where-ever we can. The US Department of Energy estimates that as much as 20 to 40% of heat generated by a heater could be dissipated in the duct work and never reaches its final destination. That should probably be a cheap fix -- imagine using duct tape for what it was actually intended for!
• Get a new high-efficiency gas furnace. The furnace we have right now looks like it is from the 80's. It has service labels on it from before 1996, so know it is at the very least 12 years old, but it looks much older than that. A furnace's efficiency is measured with an annual fuel-utilization-efficiency (AFUE) rating. Furnaces from the 80's typically have ratings around 65%, which means that 65% of the energy in the burning natural gas is used to heat your home. The other part is waste that is heating up the air above the chimney pipe outside your home. Today's furnaces by US law have to have at least 78% efficiency, but many are even more efficient than that, with some even at 97% efficiency. A new furnace has the potential to save us $114 a year on the heating bill, not to mention saving 82 therms of gas or 984 pounds of CO2.
• If we really get intrepid, we can install heating "zones" in the house. That is, we install various thermostats that control the opening or closing of vents to regulate which parts of the house get heated at which times. That helps efficiency by only heating those parts of the house where we are located. For example, we could put the rest of the house at 50F and our bedroom at 62F when we are sleeping. I am not sure how much a system like that might cost though...