The Aim of the SHGC Constant

The Aim of the SHGC Constant SANS 204 describes several options for architects to reduce exposure of windows to solar radiation and uses the Constant to hold the designer to a window area limit in each cimatic zone. Radiation is the movement of heat as infrared energy through glass. The New Building Regulations require that the SHGC Constant must apply to the combined effect of the frame+glass. The SHGC CONSTANT for Johannesburg and environs is 0.15 and for Pretoria and environs it is 0.12. These figures represent the equivalent percentage of the net floor area of each storey of a building that can be exposed to solar radiation through windows. Without the product Thermal Test figures you have to use the worst case Table 6 in SANS 204 to calculate your plan against the Constant. For example, in the single occupancy building in Zone 2 shown in SANS 204 with a net floor area of 60 square meters only the equivalent of 12% or 7.2 square meters of window area per storey is allowed UNLESS you can reduce the exposure factor with a combination of better orientation, well placed shading and choose a product with a lower SHGC. KPJ wood shutters placed outside windows that are exposed to solar radiation will make a big contribution to meeting the Constant Thermal testing of frame+glass will show the real SHGC of the product. The resulting figure will depend on the type of frame and glass used and how well it prevents solar radiation from being transmitted through the window. The importance of having the Thermal Test figure is that the architect can choose the right product to maintain the goal of keeping the building bright and airy. You will always start your plan with a lower SHGC by choosing KPJ wooden windows and glass doors You Can Do More with Wood Your Guarantee of Excellence KPJ windows have been tested and certified by AAAMSA, SAGGA and SAFIERA SARIERA Accredited Manufacturer of Energy Efficient Windows