Insulation is one of the first retrofit energy efficiency interventions that should be considered.The roof cavity is the largest area in most homes of heat flow downward in the summer months and heat flow out during the winter months.
Firstly and most importantly in South Africa your Radiant Heat Flow (passive heat from the sun) is your biggest contributing factor during summer months, in order to combat this, a Radiant Heat Barrier (installed just under your roof covering) should be used in conjunction with an air space under your roof tiles or roof sheeting, this wonderfully effective technology stops the flow of Radiant Heat into the roof cavity and if correctly installed can reduce the heat in this space substantially.
Secondly if the radiant heat barrier is used in conjunction with a minimum of 100mm Bulk insulation (of which there are many forms) on the ceiling, it can be very effective in targeting both radiant heat and conductive heat flow (heat generated within the home that is lost through the ceiling or walls).
Effectively making the roof cavity energy efficient as well as achieving the energy efficiency requirements recommended in the National Building Regulations as a minimum mandatory standard. A home owner should understand that this is one part of making an energy efficient home and you should investigate and understand all the other requirements for achieving effective energy efficiency. These include windows, openings, ventilation, heat gain, heat loss, sealing of building and energy usage.
New buildings are required by law to insulate and meet the requirements of the standard, this is not the case however for existing buildings, but home owners should seriously consider this when renovating or improving your home. In the case of retrofit, one should use an approved installer who understands the how, why and wherefores of sealing the roof cavity as effectively as possible. Correctly installed product which includes all safety considerations like wiring and down lighters is imperative.
There are a number of Foils and Bulks which all fulfil the function, come at various prices and manufactured and installed in various different ways. Ensure that a product meets the minimum R-value (how much a material resists heat transfer) requirements. However A foil should always be used under the roof tile and the bulk material on the ceiling between the trusses to fit snugly and to seal all areas where heat flow may occur.
It is a good idea to get in an expert to give advice on how best to insulate your home. This is not an inexpensive exercise so it is important that when making the decision you are well informed and prepared for the financial outlay, which although not seen will go on working and saving energy and therefore money for years to come.
Contributed by Ann Davies owner of INSUL8 WHY WAIT?