Airbase publication

Building system engineering can help decrease the risk of being infected by the aerosol which contains virus-laden droplet nuclei. Many techniques can help decrease the concentrations of particles. This paper focuses on the economic renovation of the existing ventilation system of a public commercial space, a small meeting room in Kuijpers, Leiden, to decrease airborne transmission of respiratory infectious diseases.

Schools had covered special attention in the last year, due to their importance to organize daily work as well as since most of the children were still not vaccinated. Under this circumstance, the importance of air renewal to reduce the probability of COVID-19 contagion inside buildings was highlighted. 

Throughout history, the human population has experienced major outbreaks of infectious diseases. In December 2019 the previously unknown SARS-CoV-2 virus emerged, which had a huge impact globally. Residents of long-term care facilities (LTCFs) showed to be highly susceptible to infection due to their frailty. Respiratory infectious diseases, such as COVID-19, can spread among others via the airborne transmission route. This is caused by sharing the same indoor environment.

In this study, a sensitivity analysis on the effects of inhabitant behaviour on the performance of ventilation systems is carried out. Inhabitants behave differently in terms of presence at home, window opening, door opening, etc. Relating to the ventilation system, this is reflected in the ventilation demand and consequently the energy consumption, but also in the indoor air quality. Therefore, care should be taken to compare ventilation systems to each other as the inhabitants can be the most determining factor for the performance.

The impinging jet ventilation (IJV) system has been proposed as a new air distribution strategy and is expected to overcome the disadvantages of the mixing ventilation system (MV), which is the most widely used system, and displacement ventilation, which provides better air quality than MV.  

Stratum ventilation (SV) is an energy-efficient solution to provide thermal comfort and improve air quality. The air distribution in rooms with SV depends on the room layout, location of supply and exhaust grills and indoor heat gains. Therefore, the commonly used methods to predict air temperatures in the occupied zone do not usually fit the indoor temperature distribution. At the same time, detailed simulations of indoor air distribution are still mainly used in complicated room layouts and research.

Ventilation in buildings dilutes the indoor air pollutants by replacing part of the air with outdoor air to guarantee an adequate indoor air quality (IAQ). In heating-dominated climates, the exchanged air has a lower mean temperature than the indoor air, which leads to a surplus heating demand in the building. A heat exchanger recovers part of the heat from the expelled air, contributing to the reduction of the extra heating demand. Smart ventilation systems work with reduced airflows, without compromising the IAQ and lowering the heating demand.

A balanced ventilation system can be combined with an air-to-air heat pump. Such system combines the refreshment of the air in a house with heating and cooling of the fresh air in order to influence the indoor conditions like temperature and humidity. Depending on the season in the year, various modes are used to deliver fresh air and condition the incoming air to the desired levels.  

In a context of energy use reduction, low energy buildings are becoming more widespread. This kind of construction requires a good envelop airtightness to prevent uncontrolled leakages of conditioned air leading to energy losses. As a result, more and more ventilation systems are installed to ensure a sufficient air change rate for a good indoor air quality. 

Energy efficient buildings are getting more and more airtight to avoid thermal losses through uncontrolled air leakage and rely more and more on mechanical ventilation to ensure a good indoor air quality. In practice ventilation systems are however not always perfectly installed, and several problems are often encountered on-site. 
In France the new environmental regulation for new buildings RE2020 now includes a mandatory inspection of ventilation systems for non-residential buildings.