Achieving a pleasant indoor environment in both summer and winter
Thermal comfort in summer
Thermal protection in summertime is characterised by the time in hours that it takes for the heat present underneath the roof covering to reach the inside of the structure (phase shift), and by the associated increase in the interior temperature in degrees Celsius (°C) relative to the exterior temperature (amplitude damping).
Cool interiors during hot summer weather
To quantify thermal protection in summer, the phase shift and amplitude damping should be calculated. An airtight thermal insulation structure is assumed here. The heat is conducted to the interior in a relatively sluggish manner (depending on the type and characteristics of the insulation material).
Quick heating up due to air flow
Gaps in the airtightness layer result in air flow from the outside to the inside and thus also in a high exchange of air as a result of the large differential in temperature and pressure between the indoor and outdoor environments. The thermal insulation can then no longer contribute effectively to summer heat insulation and an unpleasant, excessively warm room climate is the result.
Preventing unhealthy indoor environments in winter
The relative humidity in homes should be a comfortable 40–60% during the heating season. A room climate that is too dry is bad for our health.
Mould formation due to condensation
Damage to structures caused by mould formation may occur when humid, warm indoor air enters into the thermal insulation structure in winter – e.g. through gaps in the vapour retarder and airtightness layers – and large amounts of moisture condense. Many mould fungi release poisons – such as MVOCs (microbial volatile organic compounds) – and spores as secondary metabolic products that are harmful to human health. These are a leading cause of allergies. Humans should avoid all contact with mould fungi. It does not make any difference in this regard whether the MVOCs or spores enter into the human body in the stomach through our food or else into the lungs if they are present in the air we breathe.