In our day-to-day life, we spend a lot of time indoors. Our homes, schools and office buildings today are increasingly well insulated. A good thing of course, but unfortunately not for air quality because there is little air flow through this insulation. It has been shown that indoor air quality can be up to 30 times worse than outdoor air. This can lead to various health problems, such as headaches, shortness of breath, asthma, hay fever and bronchitis. But should you sit next to the open window all day? Certainly not, for clean air you really don't need to be cold in winter, hot in summer and sneezing because of pollen in spring.