A thermal and moisture report helps select the layers of a building element if it describes the actual wall and its conditions of use. A green result in the calculator alone does not explain the behaviour of corners or the effects of leaks. For new construction, it is worth preparing the data so that the calculations can also be used when coordinating windows, installations and the sequence of works. A wall separating a flat from the outside performs differently from a building element between a workshop and a cold store. Record the design temperature on both sides, the heating method and the expected humidity. In a bathroom, laundry and utility room, the sources of vapour behave differently from those in a bedroom. It is also important whether the heating will operate continuously.

Preserving the historic façade may direct attention to internal insulation. In a tenement building, however, this is not a simple substitute for external insulation. Old walls, timber elements and different ways of using the flats require a joint assessment. The choice of PIR should result from an appraisal of the building, not be the first decision in the works plan. The inability to alter the façade does not automatically mean freedom to remodel the interior. The scope of the building's protection, the required approvals and the impact of the works on common parts must be checked. Original plaster, stucco, joinery or other interior elements may also matter. The assessment should precede ordering the lining.

Budget insulation starts with determining where and when heat is needed. A car garage, a workshop used in the evenings and a cabin for long weekends have different needs. Dividing the building into zones helps direct money to the right building elements while reducing the risk of moisture and later reworking of installations. An unheated building protects equipment from precipitation and wind, but insulation alone does not ensure a positive temperature inside. In a periodically heated building, the time to reach comfort and moisture after the heating is switched off matter. With continuous heating, losses through all external building elements become more important.