In the average home, approximately 10% of the heat loss is through the ground floor. Therefore, insulation as a means of reducing heat loss is typically installed on the ground floor. However, it may also be provided in upper-floors between heated and unheated areas. In comparison with wall insulation or roof insulation, savings associated with floor insulation are more modest, but under some circumstances, installation costs can be lower.
As UFH heats the room from the floor up it is important to prevent downward heat loss. Newer buildings that meet the current building regulations the levels of insulation will be sufficient, but in older buildings with little or no insulation, this may not be the case.
It is the responsibility of the architect and/or the builder to ensure that the insulation is adequate for the requirements of the underfloor heating and Building Regulations.
Even adding a modest among of insulation such as the 16mm included with the Total-16 system to an otherwise uninsulated concrete ground floor with an original u value of 1.2 W/m2K will save energy. While actively heating the room, Total-16 will have a downwards heat loss similar to the previously uninsulated floor when the room was heated by radiators, however if a room is heated for 8 hours a day, then for the remaining 16 hours a day the heat loss through the floor is reduced by as much as 35%, providing an excellent reduction in heat loss for a minimal increase in floor height.
Exposed Ground Floors
- Ground floors on earth or suspended floors in contact with outside air, should be insulated to limit downward heat loss, due to the thermal resistance of the applied floor finish to not more than 10 W/m².
- When heat output is not known but the floor finish is specified, the amount of system thermal insulation needed may be calculated based on the sum of the thermal resistance of the floor finish and the underlying heated later multiplied by 10.
- Floor heating systems intended for cyclical operation or installed over unheated rooms should be separated from the structural floor by a layer of thermal insulation with a thermal resistance of at least 1.25(m².K)/W.
The intermediate floor should have a separating layer of thermal insulation with a thermal resistance as in option B above for Exposed ground floors, or not less than 0.75(m².K)/W as specified in BS EN 1264-4.