Energy certificate, radon and moisture
Three investigations that often decide whether a house becomes expensive or unhealthy, what the law requires, how measurements work, and how to read the results.
Applies to: Sweden. Reviewed 2026-09-18.
Key takeaways
- Buildings offered for sale must have an energy performance certificate under Act (2006:985).
- When a valid certificate exists, energy performance must be stated in the advertisement.
- The reference level for radon in existing homes is 200 Bq/m³.
- A reliable radon measurement runs during the heating season October–April for at least two months.
Energy performance certificate
Newly built buildings and buildings offered for sale must have an energy performance certificate, as must buildings let under a right of use, for example bostadsrätt and rental. The requirement follows from Act (2006:985) on energy performance certificates for buildings.
Where a valid certificate exists, the owner must state the energy performance in the commercial advertisement.
Read the certificate as source material, not as a grade. It uses normalised energy use and says nothing about how you personally will heat the house.
Radon
The reference level for radon in existing homes and in premises open to the public is 200 Bq/m³ under the radiation protection ordinance (2018:506). For new buildings, 200 Bq/m³ is a limit value under Boverket regulations.
- Measure during the heating season, October to April, for at least two and preferably three months.
- A 2–10 day measurement gives only an approximate value and is not valid as a basis for a radon grant.
- Measure if more than ten years have passed, or if ventilation, heating or the building itself has changed.
Moisture and risk constructions
Certain construction methods are known to be moisture-sensitive, for example crawl spaces, slabs with built-up floors, converted basements and single-stage rendered façades. That does not mean the house is damaged, but it should be properly investigated: measurement, sampling and in some cases opening up.
Questions to ask
- What year was the energy certificate made and what measures does it propose?
- Has radon been measured, when, and for how long?
- Is the house built with blue concrete or located in a ground radon area?
Red flags
- The radon figure comes from a few-day short measurement and is treated as conclusive.
- The energy certificate is missing entirely although the home is for sale.
- A basement or mould odour explained away without measurement.
Sources
- About energy performance certificates (Boverket)
- Energy performance in advertising (Boverket)
- Reference level and limits for radon (Strålsäkerhetsmyndigheten)
- Measure radon in your house (Boverket)
- Land Code (1970:994) (Sveriges riksdag)