Which Radiant Heating System for the Loft?
Loft conversion and wall heating in a pitched roof
Loft conversions can increase the living space of a house, sometimes considerably. Living in a converted loft can also be very attractive. However, the nature of the space places special demands on heating and air conditioning. Wall heating on the sloping ceilings offers many advantages.
It is not uncommon for large open spaces to be planned in the loft conversion to emphasise the special features of the roof truss. New window openings often reach down to the floor. This leaves little room for traditional wall-mounted radiators.
Underfloor heating can be a suitable heating solution if the structural design of the suspended ceiling allows it. Traditional underfloor heating in a heated screed with additional thermal insulation places a significant additional load on the loft floor.
In the case of ceiling heating, the area of the horizontal ceiling section - if any - is often insufficient to provide adequate heating.
On the other hand, the wall surfaces in the loft are disproportionately large in relation to the size of the room. They are also unobstructed by furniture, which can hinder heat radiation. Wall heating on sloping ceilings utilises and supports the characteristics of the room. In addition, wall mounted radiant panel heating not only offers energy benefits and potential energy cost savings, but can also be used in conjunction with a reversible heat pump to cool the rooms under the roof in summer.
Substructure of the pitched roof heating
What to consider during installation
In most cases, the 1,200 mm long drywall panels of the ceiling heating system are suitable for thermal activation of roof slopes. Where larger areas are available, the 2,000 mm long wall panels can be used. However, the size and weight of the wall panels require a two-man installation.
The substructure is fixed horizontally to the rafters at a distance of 400 mm in accordance with dry construction guidelines. Wooden battens or galvanised sheet steel hat sections can be used as the substructure.
The drywall panels with integrated heating pipes are screwed to the substructure, avoiding cross joints. The hydraulic connection of the heating elements to each other and to the RTL control boxes is carried out in the same way as the installation instructions for the ceiling heating.
The remaining areas of the roof slopes are sealed with inactive 12.5 mm plasterboard. Installation is carried out in accordance with standard drywall practice.
Roof insulation is essential
From 2014, the GEG (Building Energy Act) requires that roofs must be adequately insulated (U-value < 0.24 W/(m2K)). Insulation must be carried out in accordance with building regulations, but it is worthwhile in most cases. Good roof insulation saves about 8% heating energy, protects against heat in summer, is subsidised by the BAFA and contributes to climate protection. To find out what you need to consider when insulating your roof and how much different types of insulation cost, go to https://energysavingtrust.org.uk/advice/roof-and-loft-insulation/
If the heating capacity of the sloping roof area is not sufficient
If the heating output of the pitched roof heating is insufficient due to the limited area, additional ceiling heating or wall heating on the straight walls could cover the heating requirement.
If there are space problems on the pitched roof, or if skylights make the design of the heating elements difficult, the drywall panels of a ceiling heating kit can also be divided between the pitched roof and the ceiling.
For high requirements, particularly in terms of cooling capacity, it is possible to use drywall panels with integrated copper pipes. These achieve a 40-50% higher heating/cooling capacity.
Ceiling heating kits
