Down jackets are warm for a number of reasons. Not only do they often have multiple layers of feathers to provide extra insulation, but the feathers themselves also create pockets of air that trap heat. This is due to the thin and lightweight nature of down feathers and their ability to effectively insulate against cold temperatures".
Three types of heat transfer are conduction, convection, and radiation. You can see this from a goose-down jacket for example. The heat moves through conduction first, then convection, and finally radiation. With insulation, it slows the process of heat loss from taking place.
Heat travels by touching the overlapping parts of feathers or fibres, with conduction through solids. Air convection happens when the heat is affected by hot molecules moving to cold areas.
The many pockets of air are trapped between the fibers which are held closely together. This amplifies the volume significantly with repetitions of radiation being slown with gaps in-between fibers.
When getting to know about insulation, you may be able to pinpoint inefficient energy performance in your home.
You can figure out some of the problems with your home insulation if you know what they are. Here are some things that can cause it to stop working as intended:
Voids happen when there is no insulation. There are many reasons for them: either accidents, poor quality insulation, or safety requirements. These latter instances offer an example of where voids come about: in recessed lighting and other such designs.
Although a small percentage, a 4% void in insulation can cause a 50% loss in effectiveness. That's why home energy is so effective.
Compression can reduce the effectiveness of insulation. It does this by squeezing out all the pockets of air that create insulation, which means there is no air to block heat from escaping.
Air that is moving through insulation (like ducts or open vents) affects the insulation's effectiveness. This is because air contains the convective heat transfer, which can increase it by up to 50%. In order to slow down this effect, compressed foam is used so
The R-value can also be greatly reduced by moisture. The reason for this is the insulation becomes more conductive. Compression takes place, voids open up, and settling occurs.
The ability to slow down heat transfer plays an essential role in hot weather conditions. The same ideas are true during the winter months and cold climates.
More about types of insulation materials