In the first part of this series, we discussed that the building structure, energy efficiency, indoor environmental quality, and moisture management all need to be considered simultaneously to ensure durability of materials and control cost of near-zero energy buildings. These factors must be addressed through contributions of the whole design team. It is also evident that building physics must take an active role in development of near-zero energy buildings. The need to ensure good indoor environment and durability of materials and limit the cost of buildings led to integrated design process that now is typical in Canada for design of low-energy buildings. Furthermore, interactions between energy efficiency, quality of indoor environment and moisture management led us to introduce a concept of “environmental control.” In the meantime, we made an unexpected observation—Vancouver dwellings in 2002 use the same amount of energy as 1920 uninsulated masonry buildings erected in the same location. We concluded that despite having advanced technology, our lack of vision prevents us from an effective use of this technology. With the quest for sustainable buildings, we should learn more from termites, who appear to master the art of hygrothermal control better than humans as they are capable of maintaining highly stable interior comfort zone without heating, ventilating, and air-conditioning equipment. Nevertheless, whatever progress is achieved in new low-energy buildings, it is lost when rehabilitating existing buildings because there an owner will typically do one step at a time. If the financial constraints do not allow for more, this first step should be an integrated action that includes a combination of insulation and heating systems.
The paper presents the problem of windwashing in partitions including air permeable thermal insulations. There are technical solutions, which deliberately accept the filtration of air in the insulating layer, guided by the necessity of possible drying of building materials. Some scientific papers even suggest that the air infiltration decrease the heat losses through ventilation. In result there occur heat losses in building heat balance which are underestimated and therefore difficult to take into account during calculations. Heat changes on the inner surface of the building partition occur with a delay to the initiation of the wind. However, even the short-term local wind speed loads on thermal insulations result in temperature decreasing and therefore possible condensation on the inner surface of the building partition. The article presents laboratory measurements of air permeability of loose mineral wool and laboratory investigation of the impact of air filtration on heat transfer in lightweight partitions filled with loose thermal insulation.
Fibrous materials are characterized by good thermal properties, but are susceptible to air filtration. Effective air and wind protection of the building envelope eliminate the problem of air penetration of fibrous materials, but there are still many buildings where this protection has not been applied. Authors investigated the effect of moisture content on the air permeability of chosen loose fibrous materials: mineral wool, wood wool and cellulose fibers. The presented results may be used to simulate and calculate heat loses in existing buildings.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.