Factors affecting the performance of ventilation cavities in highly insulated assemblies

The article presents experimental studies of typical Finnish highly insulated (HI) envelopes with thermal resistance values ( R value) for the wall and roof inside ventilation cavity between 7.7 8.1 m 2 K/W 13 K/W, respectively. conditions in cavities were studied by using increased exterior part cavity, which 0.18 1.57 walls, 0.13 2.13 roof. With higher temperature only after closing inlet gap cavities. If was closed, restriction outlet from 20–25 mm to 10 had no significant effect on temperatures. A closed resulted absolute humidity indicates that should be made care avoid impairing drying-out ability. computational analysis showed optimal air change rates HI structures 4–40 1/h 20 1/h, conventional 22-mm-thick wood cladding enables safe walls if vapor barrier is tight other moisture sources are low. lower heat flux additional loss caused cloudless sky at night support observation roofs have a risk. In roofs, value least range 0.3–0.4 achieved, example, 20-mm-thick mineral wool board under roofing. use mold-resistant materials recommended mitigate possible ramifications behavior roofs.