In accordance with the global trend to regulate the design and construction of
buildings for maximum energy efficiency, South Africa has recently updated the National Building Regulation, most specifically the SANS 10400.
The new regulation stipulates that all new buildings, additions and alterterations to existing buildings must comply with energy-efficient standards, including the insulation of floors, walls, windows, ceilings and roofs.
Insulation specifications vary according to the climate zone and its required total R-Value. Coupled with this the direction of heat flow is considered to be predominant for the hours of occupation of the building. The new regulation takes into account the higher rate of occupancy of houses at night than during the day. In summer, heat moves downwards, and you must stop the heat coming through your roof and ceiling and warming the house, while during the winter, heat moves upwards, and you must avoid heat loss from the building.
If you have under-floor heating, heaters or fire places, you must retain the heat. the R-Value is the measure of the insulation product’s abaility to restrict heat transfer. It is thus indicative of an insulation performance – ther higher the R-value, the better the performance and effectiveness of the insulation product. The R-Value of the roof and ceiling assembly are added together to give the total R-Value. This is the reason all material that is related to roofs and ceilings and that is SABS standard, will have an R-Value rating.
The Midlands area falls into two zones. Zone five, which must reach a ceiling or roof R-Value of 2.7 and floor R-Value of 1.0, with the direction of heat flow downwards. This area stretches from the coast to a line that runs roughly from Hilton to Dalton and Harding – all areas that recieve less than five days of frost on average a year. The rest of midlands above this line falls into zone two, which must reach an R-Value of 3.2 and floor of one, and the direction of heat flow is upwards, as those areas are much colder and not as hot as zone five.
The regulation will be activated by an architect when he or she draws up house plans, making sure that the material used adds up to the required R-value. It is then policed by the municipality that passes the plan. There is talk that a law will be introduced that any house built recently (the date to be specified) that is sold, will have to be “insulation compliant”, simiular to being electrical compliant, before new ownership can take place – providing another way to insure that the regulation is followed.
All the above will save the country electricity and the home owner money on the amount of energy comsumbed. A typical uninsulated home loses and gains up to 35% of its energy through the ceiling, and this can be dramatically reduced by installing insulation of the correct thickness. There are two main types of ceiling material used, namely gypsum board and IsoBoard (XPS). Both are manufactured in different thickness- the thicker, the better the insulation. What restricts the thickness’s is mainly price, amoung other things.
Of the two materials, the IsoBoard has a much higher R-Value, thereby helping to get to the required R-Value more cost effectively and efficiently. Both materials cannot alone, get to the stipulated R-Values, as another material is applied on top of the ceiling to get to the target R-Value. Products used to lay on ceilings include cellulose fibre loose-fill, such as treated paper and woodshavings, which are blown ontop of the ceiling, or a firbeglass blanket that is typically made from Silica sand and 80 % recycled glass ( making a glass wool), and finally a “blanket” made from100% recycled plastic bottles namely IsoTherm. These products are installed above the ceiling and between the roof trusses.
On average, the usage of electricty in the home is: water heating 35%, space heating and cooling 28%, food preperation 22%, lighting 10% and kettles 5%. A typical uninsulated South African home loses energy as follows: ceilings 35%, Windows upto 10%, walls up to 25% ( depending on construction), floors up to 20%, and air gaps up to 10%. Note that the internal environment in your home can also be effected by the rooms orientation ( North is hotter) and the shading which would be the roof overhang or awnings to shied the northern windows.
Insulation is often considered a luxury overlooked when building a home, yet it’s primary purpose is to save energy and improve home comfort. To insulate a ceiling and geyser system properly in a typical home costs less than one percent of the total building costs, but it is one of the few building materials that will save you money for the life span of your home.