A great indoor climate
It is characteristic of low energy buildings erected by modern principles that the indoor climate is significantly better than the indoor climate in traditional buildings.
The good indoor climate is documented e.g. in a study of a residential area with 32 passive houses in the German area Kronsberg near Hannover. It shows that the vast majority, 96 % of the residents find the air quality in their home either good (50 %) or very good (46 %) (Agentur für Umweltkonzept, 2001).
This is due to the fact that the well-insulated home does not allow draughts while the use of automatic ventilation provide fresh air indoor by changing the air frequently.
As a result of the good indoor climate, people become sick less frequently, and their efficiency and productivity is enhanced. In this way, billions of euros can be saved by investing in a good indoor climate.
Old, uninsulated building
Despite new windows, condensation and mould problems can occur around window frames, the foundations, in joints and behind cupboards.
Out-door temperature: - 5° C Indoor temperature: 20° C
Surface temperature: around 9° C
Renovated building
200 mm insulation (Passive House technique) & new Passive House window
Out-door temperature: - 5° C Indoor temperature: 20° C
The relevant surface temperatures are now above 16° C and no condensation and mould problems occur. A humidity of 62% is no longer a problem.
15 liters of moisture
In any building, moisture must be ventilated out of the building. An average family of four contributes up to 15 liters of moisture to their indoor air every day. Clean, fresh air is vital for people’s well-being and a poor indoor climate can cause headaches and discomfort and impair the ability to concentrate.
No cold feet, but lots of fresh air
Rockwool International has developed and built a low energy single-family home in the Danish town of Seest to serve as a demonstration project. The family who lives in the house evaluates the indoor climate in the following way:
"We have a wonderful indoor climate in every possible way. It is light and airy, and the air is always fresh and pleasant. The morning air of stuffy bedroom and bath is quickly gone, thanks to the good ventilation system."
"We are also delighted to have escaped the cold and draught; this house is tight. We came from a leaking 1960ies terrace house, but in our new low energy house, we experience no discomfort from draught at all. It has made us quite "intolerant" when we visit friends and families who live in older houses where we notice the draught problems immediately."
Finally, the family also mentions the good acoustics of the house as essential to their good indoor climate.
“We have a wonderful indoor climate in every possible way”, says the family who lives in Rockwool International’s low energy demonstration house in Seest in Denmark.
How insulation helps
Properly fitted insulation helps provide a pleasant and stable indoor temperature between 20-26 oC – also during cold winters and hot summers. You can never insulate too much, but if you do not insulate properly and ventilate too little, you can risk warm humid air condensing on cold, poorly insulated surfaces which will create moisture that allows for moulds and fungi to grow.
