English

This work is part of two French research projects “Durabilit'air1” (2016-2019) and “Durabilit'air2” (2021-2024), that aim at improving our knowledge on the variation of buildings envelope airtightness through onsite measurement and accelerated ageing in laboratory-controlled conditions.   
The content presented in this paper is based on two publications in past AIVC conferences (Moujalled et al., 2019, 2018) and a research paper (Moujalled et al., 2021) about the mid-term and long-term changes in building airtightness through on-site measurements in low-energy houses. 

This study sets out to investigate to what extent the air permeability of a building envelope of a dwelling remains constant over longer periods of time. This was evaluated by executing an air pressurisation test in 30 dwellings located in Belgium and comparing these results to the initial measurement results obtained shortly after the construction of the buildings. The time span between both measurements ranges from 293 days to 4045 days. On average, the air infiltration rate of the building envelope increased with 24%, i.e. an increase of 64 m³/h at a 50 Pa pressure difference.

The content presented comes from the Technical Note (TN) 71 “Durability of building airtightness” published on Airbase, the AIVC bibliographic database.

Ventilation of buildings is a good way of preventing transmission of some virus in aerosolized form as the SARS-CoV-2. In many buildings, prevention strategies as window opening and sealing door have to be considered with a multizone approach. Approach. We modelled a residence equipped with a exhaust-only ventilation system where a family is isolating in a pandemic context, with one infected person. We modelled and analysed the impact of opening the window and sealing the door in the quarantine room on exposures. We tested several window- and door-opening strategies. Results.

Occupant exposure to airborne pathogens in buildings can be reduced by a variety of means, including adequate provision of outdoor air by ventilation. This is particularly important in buildings, such as hospitals, which may house a higher number of infected individuals relative to the wider population. In tropical Africa, however, there is evidence that new hospitals built with air-conditioning to cope with the extreme heat are poorly ventilated compared to existing hospitals that were designed to be naturally ventilated.

In response to the COVID-19 pandemic, many organizations have recommended improved ventilation to reduce the risk of indoor airborne infectious disease transmission. These recommendations include increasing outdoor air rates and filtration efficiencies, as well as verifying that ventilation systems are operating as intended. There have also been many recommendations to monitor indoor CO2 concentrations as indicators of ventilation or infection risk, in some cases with quantitative concentration limits.

During the corona-19 pandemic waves in 2020 and 2021, many cultural and recreational activities inside buildings could no longer take place to prevent virus transmission. In order to allow cultural and recreational sectors to reopen in a safe way by the summer of 2021, a ventilation task force of the corona commissioner's office of the Belgian federal government prepared recommendations for the practical implementation and monitoring of indoor air quality in the context of COVID-19.

The COVID-19 pandemic has prompted huge efforts to further the scientific knowledge of indoor ventilation and its relationship to airborne infection risk. Exhaled infectious aerosols are spread and inhaled as a result of room airflow characteristics. Many calculation methods and assertions on relative airborne infection risk assume ‘well-mixed’ flow conditions.

Ninety per cent of New Zealand classrooms are naturally ventilated by opening windows. Achieving a suitable ventilation level will rely on teachers. A survey showed that less than half of the teachers opened windows during teaching time. Due to the high occupant density in classrooms and a low natural ventilation rate, it is challenging to provide adequate ventilation during the southern hemisphere winter months (June to September). From 9 am to 3 pm, school hours align well with the optimum solar radiation, providing opportunities for solar ventilation.

Low or Zero Energy buildings are becoming increasingly popular and the use of passive-house principles are providing a solid foundation for achieving energy consumption targets and good indoor quality. However, this design methodology has been well received in central and northern Europe than in south and the Mediterranean, where people are used to houses that are open to the external environment. This habit is in contrast to the basic principles of the good airtightness, the energy efficiency and the achievement of a good Indoor Air Quality.