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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.  

Single-family and low-rise multifamily homes in the United States have become tighter to save energy and enhance comfort. To ensure acceptable indoor air quality (IAQ), mechanical ventilation is also required. As these systems become commonplace in the U.S., various improvements and updates have been made to codes, standards, and voluntary programs such as ASHRAE Standard 62.2, International Mechanical Code, International Residential Code, USEPA Energy Star Home and Indoor Air Plus, and USDOE Zero Energy Ready Homes. 

For years, ventilation and air-conditioning systems have played an increasingly important role in ensuring sufficient air exchange in buildings. With time buildings are becoming more and more airtight to avoid energy losses through uncontrolled air leakage and mechanical ventilation systems are installed to ensure a good indoor air quality. What is a good approach in theory can fail in practice due to leaky ductwork.

Calcium Silicate fire protection boards can be used to construct fireproof ductwork for smoke extraction and/or HVAC services. In this paper, the airtightness of the duct system is evaluated. 

In a context of energy savings, new buildings are becoming more and more airtight. The good indoor air quality (IAQ) relies therefore more and more on mechanical ventilation systems with specific air flowrates to be met. However, in practice, ventilation ductworks are not always very airtight. The numerous issues induced by leaky ductwork have been well outlined in the literature and summed up in (Leprince et al., 2020). Yet the awareness is not forthcoming, and on-site workers do not always realize the consequences of ductwork leakages. 

Control of HVAC systems may reduce congestion of the electricity grid on district level by shifting energy demand of buildings and increase the self-consumption of local photovoltaic energy. To achieve an optimal control of ventilation, occupant behaviour should be taken into account. To describe occupant behaviour, usually black box models are used and typically need large amounts of high quality training data. Alternatively, use of physical relations allows for a good predictive power requiring less training data.

The placement of mobile air cleaners (MACs) in classrooms was widely discussed between parents, teachers, and authorities in Germany during the peak of Corona infections in 2020 and 2021. Measurements of mobile air cleaner efficiencies in larger laboratory rooms indicated that there are substantial efficiency differences between test re-sults in a real room compared to results measured in a standardized 28m³ well-mixed clean test room according to a standard. The test method described here overcomes the multiple problems and uncertainties of aerosol particle decay tests.

Indoor Air quality (IAQ) of dwellings is the result of several sources and processes, and the impact of ventilation system is the one amongst many others. Definition and metrics of IAQ are several and we choose in this study to focus on airborne particle levels. Our question was: How the filtration of supply air impacts particle levels in indoor air?