So, this is may seem like you’re back at school, but understanding the basics of conduction and convection will help you make the right choices when trying to improve your home’s efficiency.
This is the simple process of heat transferring through a material without the material itself moving. Good conductors tend to be metals, whilst non-metals and gases are poor conductors.
For example, if you’re heating a pan, the pan will be getting hotter due to the electrons within moving freely, leaving charged metal ions behind. These ions are packed in tight, vibrating. This movement creates kinetic energy moving from the hot part of the pan to the cooler parts, travelling via the electrons. The electrons are full of positive energy, bumping into all of the ions, spreading the heat.
This is the transferring of heat through moving liquid and gases. When a gas or liquid is heated, the particles will move freely to take the place of cooler particles, cycling over and over in the process of convection.
As a liquid or gas is heated the particles move further apart as they fill with energy, which in turn creates more gaps between the particles. They quickly move up into the colder areas, whilst the colder particles fall down into the gaps left by hot particles.
Why does this matter at home?
If you held a thermal camera to your home you would be able to see where heat is escaping from in your home. In 2010 Anglian Home Improvements did just this on a selection of homes and you could see both of the above processes taking place. Heat was escaping from both the roof edges, in convection, and out of the windows, in conduction.
Although glass is not considered a good conductor of heat, conduction still takes place in windows so single glazed windows throw heat straight out of the window, as the cold air on the outside of the pane extracts any heat from the inside of the pane.
To prevent this, double glazing was invented, creating a gas filled barrier and an extra pane of glass between the warmth inside your home and the cold air outside. Argon gas tends to be used in sealed units at present as it is a better thermal insulator than air.
Glass technology has advanced even further than this with Low Iron glass and a Low Emissivity (E) coating being commonly used. The Low E coating is applied to the surface of the inside pane, reflecting heat back into the room. Low Iron glass is used on the outside pane of glass, which harnesses much more natural light, and therefore heat, for your home. All this extra heat is trapped by the Low E coating and the efficiency of your home is thus improved.
These are two areas to assess the performance of a window, the third is air leakage, which measures how air tight the windows are when closed.
Insulation to prevent the effects of convection
So, we now know that heat rises due to the particles increased energy and spacing between them, but they will keep rising until they cool again, which means they are possibly leaking out of your roof.
Having a well insulated roof will help you prevent this heat loss, sustaining the temperature of your home better, preventing you wasting money on heating the street.
Did you know crimped sheep wool is a brilliant insulator?
Now you have an understanding of conduction and convection and hopefully you can use this knowledge to improve specific areas of your home to increase its energy efficiency. Good luck!