The most dynamic part of the house, which also acts as a receiver, letting the sun`s energy inside and as a protection against external influences and heat losses, are certainly the doors and windows.
You have to make sure that your home is ventilated properly. It is a myth that it wastes energy and money to ventilate your home; you just have to do it correctly.
Once you have clearly indentified the type of product follow the general guidelines set out below for either timber or aluminium external finish and the internal timber finish.