The amount of heat loss from your house is highly dependent on whether the house is well or poorly insulated. In an average Swedish house, around 15 percent of the heat is lost through the roof.
Additional insulation of the attic is an investment with a very long useful life, and is often economically profitable even in the short term. We recommend that you have 50-centimetre thick insulation in the attic, which is economical from the energy aspect.
Good insulation lowers the U-value
In order to reduce heat losses, it is important to have good insulation of the outer walls, roof and foundations. The insulation properties of a part of the building are specified as the U-value. The U-value describes how much heat is lost per square metre for a difference of 1°C between the indoor and outdoor temperatures. Ten centimetres of insulation give a U-value of about 0.5 W/m2K (watt per square metre, Kelvin). An insulation thickness of 50 centimetres lowers the U value to just over 0.1.
Building a new house
If you are building a new house, good insulation is very important. The additional cost of a little extra insulation is relatively low compared to what it would cost to insulate when the house has been completed.
Bear in mind
The indoor climate can be changed by additional insulation. Additional insulation in the attic lowers the temperature in the attic space. This may lead to moisture in the air condensing and causing moisture damage. Seal carefully so that no air will enter the attic space from the house. The air may otherwise raise the humidity of the air in the attic, and this may make the moisture problem more serious.
You can also provide additional insulation in the basement. Take the opportunity to insulate it on the outside when arranging drainage around the house. Internal insulation may be appropriate if the basement wall is dry. You may otherwise have moisture problems inside the basement wall.
Seal the windows and doors
A relatively inexpensive and simple measure for saving energy is to seal the windows and doors. The investment cost for the draught-excluder strips and the time you devote to this will soon be repaid by reduced heating costs.
However, it is important to know the type of ventilation in the house. If it is a fully controlled exhaust and supply air system, the aim is that the house should be perfectly tight and that the air admitted should be regulated. Sealing the windows and doors in such a house is a very appropriate measure. On the other hand, if the house has natural draught ventilation based on air being admitted through gaps in the house structure, the indoor climate may be problematic if you seal the house too tightly.