Summer
Airtightness Ensures an Adequate Heat Protection in Summer
From the point of view of construction physics thermal protection in summer is defined by the parameters of phase shift and amplitude damping (in simple terms, delayed heat arrival). Phase shift refers to the time (in hours) which the heat requires to pass from the underside of the roof tiles into the living space.
Amplitude damping describes the temperature increase inside in proportion to the outside temperature. Both variables are calculated from the thermal diffusivity (ratio of thermal insulation to heat storage), the thicknesses of the structural components and their configuration.
The prerequisite is the assumption that the heat has to make its way inwards pore by pore (as with the U-value in winter).
Ideal
The construction is airtight. The heat has to progress pore by pore.
The heat protection in summer is dependent on:
- The existence of a protective layer outside the insulating material
- The U-value of the individual building materials (thermal conductivity)
- The thickness of the construction components and their alignment
- The airtightness
Not Ideal
The heat insulating construction is not airtight. Heat enters into the insulating material from the outside and streams through the insulating material. Thus, only a fraction of the heat insulating material is available for the actual insulation.