but these should be rooms that are not used often , like spare rooms , storage rooms and even bathrooms .
FLOORS If underfloor heating is used , the regulations require an insulating layer with a R-value of not less than 1 . It is advisable to use insulation regardless of whether underfloor heating is to be installed or not , as a lot of heat can be lost through the floor and into the ground below . This insulation is usually in the form of rigid polystyrene boards laid on the ground before the concrete floor is cast .
WALLS The composition of the external walls of a building must achieve a minimum R-value appropriate to the climatic zone in which the building is situated . The R-values of all elements are added together to get a total R-value . For example a typical double-skin brick wall will combine the R-value of the internal plaster , each row of brickwork and the external plaster . Currently this type of wall construction meets the minimum requirements inland , but there is talk that the soon-to-be-released revised regulations may require inland buildings to have cavity walls as standard , as is required at the coast . If one decides to use an unconventional building method , like timber frame construction , then the R-value of each component of the wall needs to be calculated from outside to inside and added up to achieve the required efficiency .
WINDOWS ( FENESTRATION ) The regulations require that the size of windows relative to the floor area of rooms be such as to minimise loss of heat during winter , and to prevent excessive sun in the rooms in summer . Once again the performance figures required are based on the six climatic zones . The basic principle is that the bigger your windows are relative to the floor area , the more difficult it is to conform . It may be necessary to use double glazing and more efficient frame options to avoid heat loss , and / or shading mechanisms to reduce heat gain .
ROOF ASSEMBLIES One of the biggest contributors to heat loss and heat loading in a building , along with windows , is the roof . The regulations once again refer to the different climatic zones , and the slightly different performance figures required for each zone .
All elements that make up the roof , including the ceiling , roof covering and even air gaps , have their relevant R-values added together to achieve a certain performance figure as required in the regulations . These basic components of the roof are insufficient to achieve the required figures , so the bulk of the requirement has to be made up of some form of roof insulation . The insulation ranges from your typical fibre blankets or blow-in loose fill fibre to rigid polystyrene boards . The requirements are a lot more stringent than the typical 50 mm thick fibre blankets ( aerolite ) that we have all used for the past 50 years . In order for the insulation to be effective , it needs to be about 130 mm thick .
This is not limited to the typical pitched roof construction with tiles or sheeting , but also affects flat concrete roofs . Even though a concrete roof seems quite thick and dense , its insulation properties are not that good , so insulation is usually required – either under the slab as a ceiling , or on top of the slab and then covered with the screed . This insulation is usually in the form of rigid polystyrene boards , but there are other products like concrete additives and lightweight insulated screeds that can be utilised .