Hur ofta bör småhus sotas? : En samhällsekonomisk analys av ändrade sotningsfrister

Sammanfattning: Sweden recently changed the national regulation of chimney sweeping. This study has two purposes. The first purpose is to evaluate the effect of this reform to see if the new regulation has led to an effect in terms of increased chimney fires in single-family houses and for the wood-burning and oil-burning stoves, respectively. The second purpose is an updating of a previous study (Mattsson 1994) of analysis of society´s benefits and costs of different alternative sweeping frequencies for wood-burning and oil-burning stoves. This study also has a secondary purpose to examine the extent to which the local sweeping rules vary with climate conditions.  Mattsson, based on his results, proposed that the sweeping requirements for oil-burning stoves should be reduced from twice a year to once every second year and for wood-burning stoves the sweeping should be reduced from four times to once each year. Recommendation for oil- burning stoves was implemented in the new regulation from 2003. The results from the statistical analysis show that the differences between the various municipalities sweeping frequencies cannot be explained by differences in climate conditions, i.e. municipalities don´t have perfectly adapted the sweeping frequencies with temperature. The results even show that the reform of year 2003 has led to fewer chimney fires.  Results from the cost-benefit analysis show that for oil-burning stoves, a cut from a sweeping every two years to a sweeping every three years is socially efficient if the value of the environmental factor is below 60 kronor per stove and year. For wood- burning stoves, a cut from 3-5 times to once each year would be efficient if the value of the environmental factor is below 1290 kronor per stove and year.