When buying a house

When you are thinking of buying a house, it is important to consider how much energy the house uses.

Here are a few tips as to the areas you should be particularly aware of.

The heating system

Of the total amount of energy used in a home, approximately 60 % is for heating. So your house’s heating system has a major impact on your economy.

If the house has a water-based heating system, you can connect new heating sources such as a pellets burner or a heat pump.

If on the other hand you want to convert from direct electricity, you must install new pipes and radiators for your new central-heating system.

It is both simpler and cheaper to supplement electrical heating with other heating sources such as a heating stove, a heat pump or a tiled stove. In order to reduce the costs for the energy you purchase and reduce climate impact, you can also supplement with solar heating.

If you choose to supplement electrical heating with another heating source, you are still, to some extent, dependent on electricity for your heating.

Don't forget that everything has a limited service life. A heating system may need to be replaced after 20 years. You should therefore ask how old the heating system is.

Read more about heating system.


Find out how thick the insulation is in the house. A well-insulated house should have 50 cm of insulation in the loft, 30 cm in the walls and 20-25 cm floor or ground insulation.

In older houses, insulation in the loft is usually no greater than 15-20 cm. By adding extra insulation to the loft, you can reduce heat loss through the ceiling by approximately two thirds. It is important that there is sufficient ventilation in the loft above the layer of insulation so that any moisture can escape.

When the house was built reveals quite a lot about the house’s energy consumption. During the 1940s, builders started to care about energy consumption in buildings. This led to both houses and windows becoming smaller. Heating insulation became standard during the 1960s. Following the oil crisis during the 1970s, a building norm was introduced which resulted in houses being built with better insulation than before, even if we now feel that the thickness of the insulation used then is not sufficient.

Mixing different types of insulation material can produce problems. If for example you have sawdust, which is an organic material and which "breathes", and you add mineral wool which is inorganic on top, there is a risk that the moisture from the sawdust gets drawn up into the mineral wool with subsequent moisture problems.

Read more about insulation.


A lot of heat disappears through the windows in a house. It is therefore important to find out how well the windows insulate. You can find this out via the window’s U value. The lower the U value a window has, the less heat losses there are.

New energy-efficient windows have a U value of 1.1 or less while triple-glazed windows without a thermopane have a U value of 2.0. Most older houses still have double-glazed windows with a U value of 3.0. Their insulation is three times worse than energy-efficient windows.

Generally speaking, it is not necessary to change the windows if they are in good condition. Instead you can change the window panes and use low-emission glass which is coated and which impedes heat radiation. You can also install a third pane or a so-called thermopane unit. A thermopane unit consists of two or more panes of glass with one or several coats and a space between the panes which can be filled with an inert gas which improves insulation qualities.

Read more about windows.


Good ventilation is extremely important to ensure that the house and the people living in it feel good.

Houses built before 1970 are generally ventilated via a natural draught system. This means that new air comes in through ducts and gaps/openings in the house and heated air leaves the house through ventilation channels in for example the bricks and through waste air ducts in the bathroom.

You can easily check to see whether the ventilation goes in the right direction by holding a piece of toilet paper just under the waste air duct. If the paper is sucked in towards the duct, the air is travelling in the right direction and the ventilation system is working.

A house with a natural draught system often has considerable energy losses and poor air exchange, something which can lead to damp problems. Damp problems can also arise when you replace an oil or wood burner with a heat pump or with district heating. Be attentive - damp problems are often something you can smell. Clothes and other textiles smell stale or musty if you have problems with damp.

Houses built in the 1980s and after usually have a mechanical air exchange system which enables you to recycle heat in the ventilated air.

Read more about ventilation.

Hot-water heaters

A well-insulated hot-water heater is necessary in order to keep down your water-heating costs. Older hot-water heaters are often poorly insulated.

Find out whether the hot-water heater is of the right size to cover your household needs. A storage heater which can accommodate 200 litres is often sufficient for a family.

It is also a good idea to find out whether there is the possibility of connecting a hot-water heater to other energy sources, solar power for example.

Read more about hot-water heaters.

How much hot water your family uses has an important impact on your total energy cost.

Read about how to lower your water consumption.

White goods

Find out as much as you can about the white goods in the house. The difference in energy consumption between old and new household appliances is often considerable. Ask whether the fridge, freezer, dishwasher and washing machine have recently been replaced and what energy classification they have. All white goods are now energy-rated according to the EU's seven efficiency classes from A to G, where an A product is best - from an energy point of view - while a G product is worst.

Read more about white goods and energy labelling.

Examine the house carefully

As the buyer, you are responsible to carry out a thorough examination of the house. You are buying a house in the condition that it is at the time of purchase and you cannot receive any money back afterwards for faults or problems which you should have detected during the inspection.