Wasted energy and inefficient energy performance is a common complaint in most households globally. Knowing the science behind insulation and heat transfer will help you highlight wasted energy within your household and how to increase the efficiency of energy performance in the highlighted areas.
Insulation: insulation is the process of slowing down heat transfer. A perfect example of insulation at work is a Down Jacket (goose-feathered jackets). Down jackets surprisingly keep us warm on a very cold day despite them being made of a couple of very light feathers. It may seem mysterious and unbelievable how light feathers could keep us very warm. However, it is no mystery; it’s all the science of insulation and heat transfers.
The secret to the warmth of goose-feathered jackets is the small pockets of air between the feathers. The small pockets of
air act as insulators. Heat normally moves in 3 ways: through conduction, through convection and through radiation. Conduction is heat transfer between solids while convection is heat transfer between liquid or air particles. In a down jacket, heat transfer happens in all the three means. First by conduction; from feather to feather, the feathers however have to be in contact with each other for conduction to take place. Heat transfer by convection and radiation takes place but is slower. Convection happens in between the air pockets in between the fibers while for radiation each fiber has to produce its own heat hence is slower. The air particles hence prevent heat loss from your body and keep the heat within the feathers hence keeping you warm. The small air pockets act as “heat-guards” ensuring no heat is lost from your body to the environment.
With that knowledge of heat transfers and insulation in a down jacket we can now take a look into what happens in our homes.
Here are common causes of inefficient energy performance in households:
1. Voids: voids are places where there is no insulation. Voids may be as a result of accidents or poor quality insulation or as a result of safety requirements. An example is recessed lights; recessed lights are normally not rated for lighting. According to home scientists, a small 4% void can create a 50% loss in effectiveness.
2. Compression: compression squeezes out all of the air pockets which were initially acting as insulators. Hence, compression reduces the effectiveness of insulation.
3. Movement of air through insulation: the air pockets have to be dormant for insulation to take place. When the air pockets move the heat is lost through convection. Hence, movement of air through insulation reduces the effectiveness of insulation.
4. Other factors: the presence of moisture reduces the effectiveness of insulation because the insulation becomes more conductive hence more heat transfer.
Insulation plays an important role in households; in keeping the houses warm during the cold season as well as keeping
the houses cold during the hot season. The household however has to avoid and minimize things that may interrupt and lower the efficiency of insulation; insulation voids, compressions, movements of air through insulation and other factors such as moisture. This way the households are able to cut down on energy wasted as a result of inefficient insulation.