Let’s start with the basics. For the purposes of our conversation insulation does one thing. It resists the flow of heat from one location to the next. Think of a good insulator as a material that is really good at keeping heat from transferring from one location to the next.
Take a thermos. You put your hot coffee in the thermos, you go out for a ski and in about an hour you stop. Your thermos has been exposed to the 5 degree temperatures but when you pour your first cup it is still as hot as when you made it. It is a simple concept. The thick walls of your thermos have resisted the heat transfer that takes place because heat is seeks to move from a region of high heat to a region of low heat.
The insulation in your thermos keeps the heat in better than say a ceramic cup which transfers heat from the hot liquid to the outside surface of the cup to warm up your hands. That heat is leaving the liquid at a much faster rate than the thermos. Resistance is the key word here. We actually call it the “R”-Value. Different materials resist heat transfer at different rates of time. The ceramic cup’s R-value is lower than that of the thermos.
In houses we discuss r-values a lot. In fact there are certain benchmark R-values that we actually try to achieve in different parts of the house. The average house that we audit usually has wall R-values of between 10 and 30. Attics R-Values range between 10 and 70. Basement R-values range between 5 and 30.
For your house to stay warm you need to add heat to it. Your heater puts a bunch of heat (Called BTU’s :British Thermal Units) into your house and over time that heat leaves the house to the outdoors. The heat generally leaves no matter what you do. You can change how quickly it leaves though.
The rate that the heat transfers through the walls, ceilings and basement is determined by the R-Value of those areas and their insulation. For houses with generally low R-values, the heat transfer (loss) happens faster so your heater has to keep adding heat to keep you warm. This is more costly to your wallet and to the environment. The idea around having high R-values is that the heat that your put into the house stays there a lot longer and you need less heat to keep your space warm for longer time.
Our next blog will cover the types of insulation.