The use of natural and controlled renewable wood building materials, in combination with a diffusion-open construction method and controlled ventilation with heat recovery, creates a healthy and very pleasant room climate. Wood is a particularly pleasant material for interior surfaces. Thanks to its low thermal conductivity, the wood building material feels particularly warm and comfortable compared to other building materials such as steel or concrete.
A distinction is made between non-visible (NSi) and visible (Si) quality. The distinction is only the appearance. The optical quality will be correspondingly higher the fewer knots or other growth-related features are visible in the surface.