Reflective insulation works in exactly the way that the name suggests. It reflects energy back into the area that it is contained within. It normally consists of a quantity of reflective sheets with air gaps between them that fill a cavity and together form the reflective barrier insulation.
Reflective insulation has a very low emmitance value. This means that it does not absorb any energy and retransmit it. Approximately 96% of the energy that comes into contact with it is reflected back into the room thus making it an extremely effective insulator.
The most common form of reflective insulation is aluminium foil. It can be used on it's own as a primary reflector or combined with another material to become a secondary insulator. A good example of this is when it is combined with fiberglass batts to form the cavity wall insulation in a timber framed building. The outer skin of the building is built first and then reflective building insulation is stapled in place on the outer frame. The fiberglass batts are then install against the foil and held in place by plastic clips whilst the inner skin of the wall is built. This provides a reflective insulation layer that reflect cold back towards the outside of the building and heat back into the room. In hot areas this has the advantage of working the other way around in summer, hot air is reflected back into the environment and cool air is kept within the building.
This foil form of reflective barrier insulation is also very good in humid conditions. It can totally enclose the fiberglass insulation that is being installed and thus prevent the absorption of water and the inherent decrease in effectiveness that this brings.
Ducts are another area that may need reflective insulation. If your duct insulation consists of fiberglass insulation wrapped around your pipes and ducts it will benefit from a layer of reflective duct insulation being applied on top of the fiberglass duct insulation. This will help to keep the temperature of the substance in the pipes constant and will also prevent the fiberglass duct insulation from absorbing water and becoming less efficient.
Another area that reflective insulation is employed is in a dry lining situation. Rather than being applied separately within the cavity along with the fiberglass insulation the reflective insulation comes pre-applied to the plasterboard that is used to dry line the walls. This reduces labor costs as it takes a two stage insulation task and reduces it to one by combining the reflective insulation installation with the plasterboard fixing.
The quality of an insulation product is measured by it's r-value. This is usually quoted on the packaging, by the manufacturer, and a high r reflective insulation is the best to purchase. It may cost more at the outset but you should recoup this extra expense many times over with reduced energy costs.
Reflective insulation is one of the many forms of insulation that can contribute to a huge reduction in the heat loss from your home.
Reflective insulation has a very low emmitance value