In spring, Swegon Air Academy hold two seminars at DTU and Aarhus in Denmark on the topic of “Renovation of Danish apartment buildings. What can be done to reduce energy consumption while increasing comfort and improving indoor environment”. Jørn Toftum is Associate Professor at the Centre for Indoor Environment and Energy, Technical University of Denmark. Jørn presented his research on characteristics of Danish homes their indoor air quality and residents’ comfort and health.
In his presentation, Jørn Toftum talked about the results of a major study of building characteristics and indoor air quality in Danish homes. Measurements showed that the homes generally had far too little ventilation. Furthermore, there was an interesting correlation between the air change and the relative humidity in the homes, particularly air changes lower than building code required (i.e. it varied from 0.17 h-1 to 0.62 h-1, compared to the building requirements of minimum of 0.5 h-1) and also there were situation where rather high relative humidity occurred in buildings (ranging from 40% to 60%). At the same time, the analysis showed that residents’ behavior had a much greater impact on air change than buildings´ characteristics.
Burning candles is a source of fine particles in the air, but his presentation Jørn showed that there is a big difference in materials from which candles are made of. Thus, the concentration of ultrafine particles (particles with aerodynamic diameter < 100 nm) is several orders of magnitude lower by burning soy candles compared to the more common candles from paraffin or wax.
Very interesting was an example of a day on Christmas in Jørn´s own home where in the morning they heat up some food in microwave, in the afternoon the oven is switched on to for preparation of a Christmas dinner and also the candles are light. Later in the evening the candles on the Christmas tree are light up and very late in afternoon where all candles and cooking are finished, the terrace door are opened. The image documents the concentration of ultrafine particles varies highly from the 200,000 n/cm3 to 1,000,000 n/cm3.
Image by Jørn Toftum