Basics Thermal Comfort – Ventilation – Solar Control

Thermal Comfort

The quality of the indoor environment is about all the aspects that can influence certain sensory perceptions, or which can affect the way people function physiologically. All the factors that feature in the physical side of construction – heat, moisture, sound, light – have a role to play here. But there are also other matters, such as the purity of the indoor air, that are important. This involves the removal of combustible products (respiration), waste substances given off by machinery (copying machines) and pollution introduced into the air by building materials (formaldehyde, radon). Thermal comfort has a prominent position in this area


Ventilation with fresh outside air is necessary for good air quality inside a building, and for controlling the indoor environment during the summer. At the same time, it is important to distinguish basic ventilation from summer ventilation. Unmanaged ventilation with outside air through (opening) joints (infiltration) is undesirable as it causes draughts and unnecessary energy consumption. For that reason, this chapter also covers the air permeability of the building shell.

The stack effect, or chimney effect, plays an important part in the driving forces for natural ventilation.

Solar gain and solar control

The strength of the solar radiation that falls on the outer wall of a building can be as much as 900 W/(m², depending on the time of year and its orientation. If the radiation is able to enter the building, it will heat it up considerably. During the winter, spring and autumn this can be pleasant, and the radiation may help save energy. In the summer, however, it can lead to unwanted increases in temperature.