For passive systems, "heavy" and "light heavy" building methods are preferred, because such buildings heat up slower, they keep heat longer without large temperature fluctuations and there is no overheating in them, so they require less airing by opening the windows. The curve in the drawing

Influence of changes in outside temperature on changes in inside temperature in buildings of various types of structure.

shows, how big are the differences in solar irradiation of light-structure houses (wooden), heavy and heavy, partially sunk into the ground. Houses of light wooden construction with well-insulated walls, they heat up quickly under the influence of solar radiation, and even overheating, so they require airing, which is a waste of thermal energy. After the solar radiation ceases, the temperature in these houses drops quickly. To compensate for its hesitations, efficient heating systems should be used. Such a reaction of light wooden houses to irradiation is associated with their low mass - thermal inertia. In heavily constructed houses, fluctuations in the outside temperature and solar irradiation do not have such an effect on the stability of the inside temperature. In Sweden, where light wooden construction dominates, in homes that use solar radiation, to improve the heat balance and increase the thermal inertia of the house, the structure of the ground floor is made of a heavy slab.

Changes in internal horizontal and vertical partitions are directly related to the method of obtaining thermal energy from solar radiation and the method of storing thermal energy..

Thermal insulation should be avoided in ceilings between levels, which constitute a barrier to the penetration of the absorbed heat. If the ceilings are used as improved heat stores and the heated air is forced through the ceiling ducts, then also no thermal insulation is used, and the floor layer must not be a material, which would interfere with the transmission of heat (wood and wood, carpets, etc..

Layer arrangement in the horizontal partitions of the house with passive heating: 1 - ceilings above the top floor, 2 - ceiling of intermediate storeys, 3 - ceiling above the heat store.

Internal structural and partition walls should also be made of heavy technology, or "light heavyweight". This is especially important with a direct passive system.
In connection with such recommendations it turns out, that the current Polish way of building houses can be easily adapted to the requirements of passive solar energy systems.