If you have walls to protect your home from the chilly winter, why does the cold still find its way inside?
In a home that isn’t well insulated, a process called heat transmission takes place. The process of heat transmission allows heat to pass through your wall from the inside of your home to the colder outside.
Insulation stops heat transmission by keeping the heat inside of your home. When the heat tries to escape, the insulation forces it into fibers and small air pockets within the insulation. The heat can no longer easily flow through air because the insulation blocks the heat’s movement. This movement through materials and air pockets slows the heat and prevents it from escaping.
The two main components of heat transmission are temperature and the movement of the heat.
By definition, temperature is a measure of how much thermal energy (heat) is available—or how much heat is available to escape. The movement of heat (also called heat flow) represents the movement of this thermal energy from one place to another. Heat aims to travel from the area of a higher temperature to the colder air.
On a smaller level, thermal energy (heat) is a measure of the how fast or slow the molecules move. The faster the molecules move, the greater the thermal energy—in other words, the higher the heat. It is natural for places with faster moving molecules to transfer some of their energy to a region with slower moving molecules—resulting in the warm heat in your home trying to pass its energy along to the colder outside.
So now we know why the heat wants to move to the colder area, but how do we know just how much heat will be transferred?
The amount of heat transmission depends on both the thermal resistance of the material the heat tries to pass through and its surface area. Insulation aims to have the highest thermal resistance possible to prevent heat movement. The surface area depends on both the size of the home and the size of the heat leakage sites.
The speed that the heat passes through depends on the temperature difference between your home’s interior and the outside temperature. If the temperature difference is greater, then the heat molecules will travel out of your home faster. Similarly, the greater the pressure difference, the faster the heat transmission.
With all of these factors going into the movement of heat from your home, there is only one guaranteed way to combat heat transmission. Insulating your home adds a protective barrier between your home’s interior and the outside weather. Don’t let the heat leave your home; hold it inside.