Radon from ground and/or construction materials
MECHANICAL EXHAUST AND SUPPLY AIR VENTILATION, (FT/FTX)
In these properties you have to start by installing a good ventilation system. If radon from ground occurs it should be an exhaust air ventilation system to minimize the negative pressure. If you want to keep the heating costs down this can be supplemented with a heat exchanger, an FTX system (supply and exhaust air ventilation with energy recovery). If the adjustment is correct, there is also always a certain negative pressure left at the ground plate. If the radon level from the ground is still too high, the air pressure in the ground under the house must be reduced by a Radon well or Radon extractor.
MECHANICAL EXHAUST AIR VENTILATION, (F-VENTILATION)
If you are sure that no ground radon occurs, a mechanical exhaust ventilation will do (F). The advantage of exhaust air ventilation is that it is inexpensive to install. NOTE! When exhaust air ventilation is installed, radon from ground may start to be drawn into the building, although it previously not occurred! To be sure that no ground radon is drawn into the building, you should choose a exhaust and supply air ventilation system, with or without energy recovery (FT or FTX system).
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