PR2019

The French ongoing research project “Durabilit'air” (2016-2019) aims at improving our knowledge on the variation of buildings airtightness through onsite measurement and accelerated ageing in laboratory controlled conditions. This paper presents the final results of the second task of the project. This task deals with the quantification and qualification of the durability of building airtightness of single detached houses. It is done through field measurement at mid-term (MT) and long-term (LT) scales.  

The airtightness of new buildings has significantly improved in the last two decades thanks to building energy performance regulations. However, until now, low knowledge is available about the evolution of buildings’ envelope airtightness. This work deals with the durability of buildings airtightness, and focuses on ways to better characterize it.

Wood is a hygroscopic material, it has the ability to adsorb or desorb water in response to the ambient relative humidity. Thus, the ambient air will affect the moisture content of the wood, and in turn, the dimension of the wood. If the wood itself is part of the air barrier in a construction, the shrinking and expansion can create gaps in the construction, for example in the window sill. In case of an air barrier consisting of a foil, the joints in the foil can be clamped by wooden joists, or the foil can be taped to wooden part.

The association between indoor air quality (IAQ) and sleep quality was investigated in this study. A total of 27 participants (14 males and 13 females, 20-33 yrs.) without any sleep disorders and chronic diseases were recruited and divided into two groups: a polysomnography (PSG) group and a non-PSG group. The IAQ was changed by opening or closing windows. There were two phases for the experiment and two nights in each phase including one adaptive night and one test night, and around one-week washout period between two phases.

More than 20 years of one’s life is spent in the bedroom when sleeping. Sleep quality is essential for our health, well-being and next-day performance. However, there is very little information on how bedroom air quality affects the quality of sleep. One of the reason could be that the accurate measurements of the quality of sleep have been the domain of sleep research groups and sleep laboratories using polysomnography. In the recent years, however, many low-cost sleep monitors and actigraphs made their way into the market.

The indoor air quality is very important for the well-being of occupants, especially in the case of young babies. This research focuses on the air quality of the surrounding air inside a crib with sleeping infants. To study the effects of different sleeping positions of the baby with in the crib a measurement setup was created in the laboratory. The breathing of an infant was simulated by means of a baby doll with air supply mixed with CO2 and measured at different sensor locations for different sleeping positions.

The estimation of low-rise, residential building infiltration rates using envelope airtightness values from whole building fan pressurization tests has been the subject of much interest and research for several decades, constituting a major topic of discussion during the early years of the AIVC. A number of empirical and model-based methods were developed, with their predictive accuracy evaluated in field studies around the world.

The ventilative cooling by natural ventilation is important technology for the buildings in urban area for the sake of energy saving and BCP (Business Continuity Plan). In fact, a large number of high-rise buildings in urban area in Japanese metropolises are equipped with natural ventilation apparatus such as openings and chimneys or shafts.

Outdoor air change qualifies the air that enters into the buildings. The outdoor air moves freely along the urban mesh favoured by the wind forces and stresses. Buildings, trees and other constructions alter the natural air flow pattern inside the cities, creating stagnated air masses in those wind-protected regions. Some outdoor spaces such as light shafts and confined light shafts inhibit the correct exchange of the stagnated air with fresh air coming from the outskirts and suburban areas. 

The work presented is the continuation of the research on the probabilistic modelling of air infiltration carried out by the author over many years. The approach has consisted in considering uncertainties coupled to the climatic/environmental input data to the physical models, or to the threshold criteria for a good performance. The concept of risk/reliability evaluation of building/environment system performance was proposed and exemplified for the air exchange model.