Filtered air - finally fresh air
One way of increasing the value of your housing stocks and generating higher rental receipts is by putting the emphasis on health restrictions of your tenants and prospective tenants.
More and more people suffer nowadays from allergies due to pollen or fine dust exposure and must therefore to a certain extent accept considerable restrictions of their quality of life. Provide the luxury to breathe "constant fresh air" through closed windows and filters installed in the unit by installing a refresh fresh air system in your objects.
Standard filters of class G4 already filter a great deal of pollen, soot and dust particles larger than 10 µm reliably out of the air. Fine filters of class F7 are even more effective.
They even filter out particles smaller than 10 µm. The filters can be replaced without difficulty. The frequency is based, among other things, on whether you live by a busy road or in the countryside.
People affected by allergies have learned to appreciate this luxury and in the mean time favour residential units equipped with a fresh air system in spite of the higher rent. Higher rents are compensated by the saving potential for the heating costs.