ventilation

More and more single-family houses are being retrofitted to achieve better energy efficiency levels. In this retrofitting process, the building envelope's airtightness is usually improved, and a ventilation system becomes necessary to create and sustain a healthy indoor air quality (IAQ). However, in France, as in many other western countries, ventilation requirements exist for new dwellings but not for residential retrofitting.

The ingress of naturally occurring radioactive radon gas from the soil into buildings can occur both by convection through any openings in the foundations as a result of pressure differentials and by diffusion across an airtight barrier (World Health Organization 2009). Residential ventilation systems and exhaust devices can affect indoor radon concentrations if they result in depressurization of the conditioned spaced relative to the outdoors or to the soil below the foundations or if they supply outdoor air directly.

Indoor air quality (IAQ) is increasingly accepted as a leading factor in human health, and the ventilation of our indoor spaces is a key modifier of IAQ as the principal means by which indoor pollutants are diluted. Knowledge of the ventilation rate is essential for understanding and modelling our indoor environment, yet quantifying the ventilation rate for regular operational spaces remains a challenge.

Steady state and dynamic simulations tools based on current ISO standards play a crucial role in designing thermal envelopes that are robust and minimise risks of interstitial and surface condensation. These tools can also be used in a forensic way when supplemented by environmental and material data from site to analyse building failure.

Children spend about 80-90% of their time indoors, making the quality of indoor environments (IEQ) crucial, particularly since children are more susceptible to pollutants due to their developing bodies and higher relative air intake per body weight. This study examines the influence of various indoor environmental conditions on cognitive performance in primary school students. Data collected over the first three weeks from a total eight-week cognitive study are analysed, focusing on the impact of thermal comfort and CO2 levels as proxies for ventilation. 

During the COVID-19 pandemic, besides sanitising, masking, and increasing social distancing, opening classroom windows was the NZ Ministry of Education's main requirement for reopening schools. However, a pre-COVID-19 survey showed that only a third of the NZ teachers opened windows during teaching time. Achieving a suitable ventilation level could not rely on humans to open windows. Heating, Ventilation, and Air Conditioning (HVAC) systems are not affordable for most NZ schools.

Improving air quality in existing classrooms can be difficult if retrofitting a mechanical ventilation system is considered too expensive or cannot be implemented due to other reasons, e.g., heritage protection. Especially in the cold winter months, window airing initiated by pupils or teachers is often not sufficient.

This study focuses on the impact of filtration efficiency level and airflow control, based on CO2, on indoor air quality described by particle concentration in an urban low energy consumption nursery school during an autumn and a winter period. Measurements of indoor and outdoor particle concentrations have been carried out by using three different filter efficiency configurations in the school equipped with a balanced ventilation system with heat recovery. The tested filters are respectively classed G4, M5 and F7 according to NF EN 779 (2012).

In France, the regulation context for ventilation is based on the decree « Arreté de 1982 » which is a prescriptive regulation, requiring extracted flowrate in every utility room. These extracted airflow should respond to several principles:

Efforts must be made to promote the use of efficient ventilation systems in buildings with the aim of reducing energy demand, as ventilation is a major source of energy loss. Nevertheless, the implementation of efficient ventilation systems is frequently constrained by regulations. It is therefore essential that governments and regulatory bodies facilitate and even encourage the use of appropriate solutions through the introduction of performance-based regulations.