Saving energy is becoming more and more of a hot issue. One of the most important fields of saving energy is insulating our homes. This not only saves energy but improves the inner environment as well. From experience in Holland we have learned that floor insulation should not be omitted in an insulation plan. Especially double glazing, which without floor insulation causes increased moisture in the area near to the floor. This can easily be explained. A large part of the moisture which used to condense on the single glass, will now be absorbed by the uninsulated floor, which has become the coldest place in the room for most of the time. (see paragraphs). It has already been proven that double glazing increases the possibility of mould in the carpet, in furniture and along skirting-boards when floor insulation has been omitted.
Research from the University of Wageningen now indicates that omitting floor insulation's also increased the number of house dust mites in the carpet. The assumption that in a home the mattress is the most significant hotbed for mites is no longer valid. The average allergen concentration in the mattresses is 5088 ng/g, the average allergen concentration in carpets on uninsulated floors in houses with double glazing is 6503 ng/g. The table opposite shows the results of a large piece of research where 512 houses were involved. The researchers concluded in their report "Floor insulation causes a significant reduction of the allergen concentration of dust on carpeted floors".In this research the average allergen concentration in the carpet on insulated floors is dominated by a U-value of 0.60 W/sq.m K. We should expect with good floor insulation (U-value below 0.30) the allergen concentration will drop far below 2000 ng/g. This is the limit value proposed by the WHO (World Health Organisation). It is presently accepted, that exceeding this limit value can cause sensitisation to house mites. It is to be expected that floor insulation will postpone the moment of sensitisation, and in many cases even prevent sensitisation from occurring.The shift of moisture problems from the windows to the floor is best illustrated by comparing the inside temperatures before and after insulation. It is obvious that double glazing is warmer than single glass and therefore increases the time that an uninsulated floor is the coldest surface in the house from 24% to 76% of the time (for the Dutch climate). A well insulated floor (U-value <0.3 W/sq.m K) is so much warmer that it will, almost all of the time, be the warmest surface.
