Radiant barriers mounted under your roofing or securely attached to the trusses in your attic will reduce your attic temperature up to about 30 degrees throughout the summer and reduce your air con bill by up 17 percent. These can be valuable savings.
Radiant heat flows in straight lines and heats anything solid in its path that is able to absorb energy. The radiant heat from the sun flows right through all the roofing material to the outer surface of the attic. This energy is radiated by the hot roof surface to the cooler attic surfaces and then to the other solid surfaces, such as the aircon ducts and the attic floor.
Steps to Follow
Similar to aluminium, a radiant barrier is a reflective surface that reflects thermal radiation instead of absorbing it. This in turn lowers your attic’s temperature. The radiant barrier limits the flow of heat to other solid surfaces in the attic from the attic roof. And by blocking the transfer of heat into the house, you can lower emissions and costs related to cooling the house.
A thin sheet of aluminium mounted beneath the roofing material; typically asphalt shingles or tile, and around the outside of the attic roof, is by far the most cost-effective radiant barrier. This installation process prevents much of the thermal energy of the sun from even penetrating to the interior of the attic roof. This technique is, of course, possible only during construction or when the whole roofing material is being removed.
A sheet of radiant protective layer, often aluminium, is most frequently built by homeowners on to the roof trusses or rafters in the attic. The sheet is stapled so that construction generally goes easy. Do not allow the installer to add the aluminium sheeting to the floor of the attic. Although this would be simpler for the installer, as dust collects on the sheet’s surface, the radiant barrier would likely lose its effect within a short period of time.
Paints infused with ceramic or aluminium particles that can be applied directly on the outside of the roof, are deemed to offer radiant barrier performance. The cost savings on aluminium sheets are sufficiently enticing to get many homeowners to go this path. But, be sure to verify the consistency of the paint by searching for an emissivity number on the packaging if this choice is ever given to you. It will be a value between 0 and 1.
The greater the value, the greater the radiation released. It should be marked 0.1 for an aluminium sheathing radiant barrier and 0.25 or lower should be given for reflective paint. If the paint label does not contain any information regarding the emissivity number, then you will not know what you’re getting or how well it works.
The thermal insulation paint can be added at a reduced cost, but it will not be as efficient as sheathing with aluminium. The compromise with the reduced installation cost would not be worth the same amount of savings as with the aluminium sheathing would have had.