Roof
roof pitch
Drempel
Flat roof
Upper floor slab
Solid ceiling
timber-beamed ceiling
Nail binder
Attic conversion
External wall
Façade
Partition joint in a house
cellar wall
Ground floor
cellar ceiling
Stairway to the cellar
Solid ceiling
Cap ceiling
Timber joist floor/cavity
Special components
In the past, radiators in buildings were usually fitted into designated radiator recesses in the wall. Even today, these old buildings often still have uninsulated external walls. However, the thermal insulation of a solid, uninsulated wall is inherently poor. If this wall is made even narrower by a radiator recess, the thermal insulation deteriorates further. The loss of heating energy through these narrow, highly thermally conductive walls is therefore enormous.
If the building façade is not insulated, or if external insulation is not required, insulation material can be installed behind the radiators – that is, on the internal wall. There are two options for insulation here.
Option 1: Ideally, as part of a heating system refurbishment, the radiator is removed and the (usually old) ribbed radiator is replaced with a flat radiator. The radiator recess can then be sealed with insulation and separated from the room by a panel suitable for wallpapering.
Option 2: If the radiator is not being replaced, with a bit of skill you can install insulation boards between the radiator and the external wall yourself.
A helpful video from the Energy Saving Commissioner
Which insulation materials are suitable? If there is little space between the radiator and the wall, insulation materials with low thermal conductivity such as aluminium-faced polyurethane (PU) WLS 023, phenolic resin WLS 021 or Spaceloft WLS 015 should be used. The latter also has the advantage that this flexible mat can be bent during installation.
All the benefits at a glance
Improved thermal insulation: If the so-called heat transfer coefficient (U-value) of the wall at its narrowest point is, at best, 2 W/m²K (watts per square metre per Kelvin), it can be significantly reduced through insulation, depending on the insulation material used and its thickness. This enables improvements in thermal insulation of up to 70 per cent.
Lower heating costs: This measure can reduce the building’s heating costs by up to 3 per cent.
Further benefits
- Comfort is enhanced due to higher temperatures on the inside of the external walls
- CO₂ emissions are reduced
- Insulating radiator recesses can also be carried out as a DIY project
- The measure is minimally invasive
Costs/cost-effectiveness: The cost of WLS 023 polyurethane panels or WLS 021 phenolic resin panels is approximately 10 euros per m² for an insulation thickness of 2 cm. Spaceloft mats cost approximately 50 euros per m² for an insulation thickness of 1 cm.
Funding: Unfortunately, this measure is not eligible for separate funding.
Can I install the insulation myself? Yes, insulating the radiator recess is a typical DIY project which – with the landlord’s consent – can also be carried out by tenants.