PR2019

The opening of windows can lead to high energy losses in wintertime, especially in nearly zero-energy buildings. But can reduce overheating significantly in summertime. Therefore, window use models have been created in the past to assess the energy use and thermal comfort in residential buildings. The models are mostly based on weather-variables. However, a recent study (Verbruggen, Janssens, et al. 2018) indicated that these models were not able to accurately predict the window use in wintertime. For that reason, an occupancy and activity based model was developed.

A ventilation performance report is mandatory for every new residential building in Flanders, for building permits issued since January, 1st 2016. This means that the features of the ventilation system as installed in the dwelling must be reported and that, in the EPB-report of the dwelling, these data must be used to justify the energy performance of the ventilation system. 

To enhance the properly functioning of the ventilation systems, a ventilation preliminary design has to be made before the physical building process is started. 

Studies in the Netherlands show that ventilation systems of dwellings don’t comply with building regulations. The main shortcoming is insufficient ventilation. This applies to both the house as a whole as to individual rooms. Ventilation systems produce too much noise, for example due to the lack of adequate silencers, the location of the ventilation unit and the dimensions of the air ducts.  Because ventilation systems make so much noise when operating at high flow, the ventilation is often only set to the lowest speed (van Dijken, 2011).

The measurement of natural airflows is practically challenging. Driving forces that induce natural airflows are characterized by low pressure differences. Conventional airflow-meters would introduce pressure drops, which can significantly affect the flow pattern. Besides, the measurement of the flow crossing a window is difficult to implement and poorly reliable. Thus, indirect methods called tracer gas methods are widely used to bypass these difficulties, as they do not interfere with the flow pattern.

Building airtightness requirements are becoming more and more common in Europe (Leprince, Carrié, & Kapsalaki, 2017). However, airtight buildings require an efficient ventilation system to ensure good indoor air quality. In France, the inspection of ventilation system (Jobert, 2012) has revealed many noncompliance. They are mainly due to bad conception, poor implementation, and lack of maintenance. This often leads to reduced ventilation flowrates and poor indoor air quality. Leaky ductwork is one of the reasons for this noncompliance.

Within the ventilation principle of buildings, the outdoor air is considered as a source of fresh, "clean" air. Outdoor air quality monitoring by environmental agencies, academic research projects and a broad range of citizen science projects show that this is not always the case. Although the outdoor air quality in our cities already improved, the concentrations of certain pollutants, especially particulate matter and peak pollutions of ozone (and its precursors nitrogen oxides and volatile organic compounds), remain problematic.

Air filters installed in ventilation systems face various types of aerosols during their service life, both in residential and in commercial buildings. Their particle size is the most important characteristic and ranges from a few nanometers to a few micrometers. Different physicochemical properties, such as phase state, hygroscopicity, and morphology are also important to determine the impact of particulate matter on the behavior of air filters during their service life.

Combustion appliances are used in many buildings to provide space heating and domestic hot water. These appliances emit smoke that contains pollutants that must be kept away from the ventilation air supply of the building, to limit their impact on the indoor air quality (IAQ). An efficient way to prevent those pollutants from entering the ventilation circuit is to place the chimney terminal above the top of the roof, as far as possible from the air supply openings.

The last decades big steps have been made on the road to develop and design energy neutral buildings. Despite the large list of developments and improvements of all kind of energy saving technologies we see specifically for the larger non-residential buildings that the electric energy use for fans hardly show any reduction and becomes a dominant factor in the total energy use of these buildings. The fan energy currently counts already for approximately 15-20% of the total building related energy and becomes increasingly important. 

Many test methods exist for evaluating gaseous-contaminant filtration media, and a few for evaluating functional filters and other devices. These test methods are designed primarily for use in product quality control and to rank products. Designers of filtration devices and HVAC (Heating, Ventilating and Air-Conditioning) systems engineers, however, need test data that allows calculation of device performance under actual operating conditions. End users need data to determine system maintenance costs. We call such tests design parameter tests.