Winter is officially here and we’ve already had some real deep-freeze days. That can trigger thoughts about the cost of staying warm and what it means to your winter gas bill. To keep costs down, it helps to understand the three basic ways you can lose heat from your home. Because that heat loss is what can really add up to extra gas usage and a higher gas bill.
Transmission and R-Value
Transmission is what HVAC pros call the process of heat escaping from your home through solid objects — like walls. You may also hear it referred to as conduction. R-value is a number that describes the resistance (R) to that loss of heat. The higher the R-value, the greater the resistance to heat loss.
Every component of a solid object — again, like a wall — has its own R-value. When component values are added together, you get increased resistance to heat flow.
For example, let’s say you have a wall made up of sheetrock, insulation, sheathing, and siding; each of those five components has its own R-value (the insulation is usually the largest). Take away one or more of those and you have reduced resistance to heat flow. So if you have an uninsulated block wall — especially one that is above ground — you can really be losing a lot of heat. Adding even ½” of foam insulation on a block wall will increase the R-value by 250%!
The same principle applies to attics, windows, and doors. Which really underscores the need for good insulation. You may want to invest in a home energy audit to help determine if you could use additional or upgraded insulation. Locally, both Xcel Energy and CenterPoint Energy offer great programs.
Infiltration is simply air entering your home. The obvious culprits here are old or leaky windows and doors. But older homes with no vapor barrier can have air flowing right through the walls and ceilings. Other areas to be aware of are pipes that go into the attic, sometimes starting in the basement. In older construction, these areas were not usually sealed.
Other places to check include anything with entry points into the attic including wires, conduits, pipes, and chimneys/vents. Addressing these may require special attention (some chimneys may get hot so it requires a professional to seal it).
Even poor construction methods used in the past can be a problem. For example, soffits in a kitchen may not be sealed from the attic, even if filled with blown-in insulation. This may look like it's doing the job, but fibrous insulation by itself does not stop air movement, it simply acts like a filter, allowing air in the wall cavity to rise up through the soffit into the attic. Unless you feel comfortable crawling around in the attic looking for these things, it’s best to hire a professional. It’s money well spent.
If your home has ductwork bringing fresh air inside, it’s important that it be a balanced amount of air. Even if you have an energy efficient Heat Recovery Ventilator, too much outside air can drive your heating bill up. It takes a lot of energy to heat outside air so make sure you are bringing in the right amount and using an energy efficient system.