Insulation is great at keeping in heat. Humans add insulation in the winter to stay warm. Animals can survive the frigid temperatures of the Arctic with their body’s natural insulation. Did you know that the fat on a polar bear insulates its body so well that they actually have to find ways to cool off? So then, how is it that insulation can also be instrumental in keeping you cool and keeping your house cool in the summer?
Keep your house cool: Understand the Flow of Heat and Air
Let’s talk about air movement and heat flow.
Air moves from high pressure to low pressure and from hot to cold. Heat travels in 3 main ways- conduction, convection, and radiation. For the sake of this article, we are going to talk about conduction (heat transfer through contact) and convection (heat transfer through airflow).
Insulation is rated on its ability to stop the conduction of heat. In the winter, the warm air in your home touches the walls, the heat moves through the material in the walls via conduction, and then escapes to the outside world. During the warmer months, the opposite is true. Instead of warmth trying to escape your house, it will be trying to come in from the outside. Having good insulation in your home will greatly reduce the amount of heat entering your home during the summer months, keep your house cool and ensure that you stay relaxed and comfortable during the hottest times of the year.
Convection is the heat transfer that people don’t talk about much, but that significantly impacts your ability to be comfortable in your own home without paying an arm and a leg. If your home envelope is not sealed tight, you are losing money. Air will flow through any gap, nook, or cranny. In the summertime, the hot air will permeate these small spaces, which will increase your energy bill and cause your HVAC units to have to work overtime!
One phenomenon related to convection is called the stack effect. In the colder months, the stack effect works by warm air pushing out the roof and cold air coming in through the bottom floor. In warmer months, the stack effect reverses as warm air pushes through to the cooler air of your home, and cooler air is pushed out the lower floors. The force of the stack effect is stronger during the winter. If your home isn’t airtight, the powers of convection are working against you, and you are falling victim to the stack effect. You are losing heat in the winter, but you are also losing your cool air in the summer.