Risk of Using Capillary Active Interior Insulation in a Cold Climate

Abstract

The retrofitting of cultural heritage buildings for energy efficiency often requires the internal thermal insulation of external walls. Most of the in situ studies of capillary active interior insulation were performed in mild oceanic climate regions, and they showed an excellent performance. However, as a large part of Central–Eastern Europe belongs to a continental climate with cold winters and long periods of temperatures below the freezing temperature, the applicability of the capillary active interior insulation in cold climate was studied. The hydrothermal behaviour of the three walls was determined—each consists of one of three different interior insulations—and the original wall is made of historic regular solid bricks. Two interior thermal insulations were capillary active (aerated cellular concrete, calcium silicate) and one vapour-tight (glass foam). A hot box–cold box experiment and a steady-state model were used to demonstrate an increase in the original wall mass due to the water condensation only when the capillary active interior insulation is used. The combination of the water condensation and the low sub-zero temperature may lead to a risk of freeze–thaw damage to the original wall. The numerical simulation of the water vapour condensation for the considered walls for the Slovenian town Bled with sub-zero average winter temperatures was performed to obtain the whole temperature and moisture profile. It showed good agreement between an experimentally and numerically obtained amount of water condensation. The capillary active interior insulation proved to be unsuitable for improving the thermal insulation of buildings in cold continental climate, and only a vapour-tight system can be recommended.

Energy retrofitting of non-residential buildings with regards to heritage value and the established cultural landscape

“…If the possibility of mould growth and interstitial condensation to occur behind the insulation system was found to be probable or high, individual case assessment in the design phase was found always necessary to guarantee the damage-free refurbishment [9]. A study on similar materials to be used in similar retrofit-projects was presented by Antolinc et.al., located in continental climate [10]. The results confirm that capillary-active insulation materials proved to be unsuitable for improving the thermal insulation of older buildings built with a similar external wall construction, i.e., single masonry walls and conclude that only a vapour-tight systems can be recommended.…”

Evaluation of the Impact of Bricks of Various Characteristics on Internally Insulated Masonry Walls in Cold Climate

“…The glue mortar can capture a large amount of moisture [22]. In another study, [23] conclusions are that capillary-active interior insulation cannot be applied in a cold continental climate and vapor-tight insulation has to be applied. They found that condensation in the masonry can appear if the capillary-active interior insulation with a relatively small water vapor resistance factor, high indoor moisture load, and no adhesive glue is applied.…”

Hygrothermal Assessment of Insulation Systems for Internal Insulation of Solid Masonry Walls under Various Conditions

“…Hygrothermal behavior during winter conditions shows that if a capillary active system has risks of interstitial condensation due to high level of an accumulated moisture content in the wall and the glue mortar, a vapor-tight system is preferable [4]. Antolinc et al (2021) found that in a room with very high indoor relative humidity, the capillary active interior insulation is not a suitable solution for improving the thermal insulation of buildings in a cold continental climate and vapor-tight insulation needs to be applied [33]. However, moist indoor air can diffuse outwards into the masonry due to mechanical damage to the vapor barrier or poor craftsmanship [34].…”