In the warmer months ventilation works to expel solar-heated hot air from the attic or roof space to reduce the building’s cooling load and to relieve the strain on air-conditioning systems and other services in the roof (e.g. electrical, plumbing etc.).During the cooler months, the primary purpose of ventilation is to maintain roof temperature and to reduce condensation and the occurrence of mould and mildew. In mixed climates, ventilation serves either role, depending on the season.
Given the variables inherent in house designs, it is impossible to provide precise guidance on what will happen to indoor room temperatures. However it is know that roof space temperatures can rise as high as 70°C, and effective ventilation systems can reduce this by 20-30°C, thereby reducing the heat loads on your ceiling and roof insulation, air conditioning ducts running through the roof space as well electrical cabling, plumbing and the roof structure itself. This improves their effectiveness as well as their longevity.
Yes, if you have a particular area in the home that gets extra hot due to its positioning relative to the sun then venting that room is definitely a way of reducing the temperature. This can be done by installing a roof ventilator and ducting it directly to a ceiling grille in the room via a length of flexi tube ducting so the ventilators primary focus can be on one room of a property rather than the entire roof space. Another option would be to install a Whirlymate ceiling grille into the room which would be left open in summer to allow the roof vent to draw the hot air from the room and expel it out through the vent with hot air from the roof cavity. Free air from the Whirlymate is used to force the hotter air in the roof cavity out through the vent system on the roof. A combination of both methods of ventilation can be very effective in reducing the solar heat impact upon homes or buildings.
It is recommended that one standard 300mm wind turbine Windmaster vent be installed for every 90m 2 of roof space (max) with a standard roof pitch (14 – 30 degrees). It is important to remember to allow the hot air to be replaced from somewhere. It is therefore recommended 4 under eave vents per 300mm wind turbine roof vent are installed if possible and ideally one internal ceiling grille to allow any hot trapped air to escape from inside your home. If under eave vents cannot be installed then gable vents are another means of providing free air to the vents needed to be installed.
In summer effective ventilation will prevent your roof cavity from getting over heated by releasing that heat. A cooler roof cavity created by releasing hot air to the outside and exchanging it with cooler ambient air via under eave vents or gable vents will reduce the need for air conditioning in the house, save you money on energy and maintain the integrity of the roof structure itself much longer.