The house dust mite inhabits bedding and soft furnishings in homes. It is implicated as a major cause of allergic asthma. Maintenance of indoor humidity below a level of 7 g/kg inhibits the growth of the mite population. A pilot survey was carried out by EA Technology in cooperation with the Building Research Establishment to investigate the effect of mechanical ventilation with heat recovery (MVHR) both on indoor humidity and mite abundances.
Avery largeelectronics factory had beencompletely refurbished, and new mechanical ventilation systems installed. In an area of the factory where the principal activity was the bench assembly of small components, there were persistent complaints of eye nose and throat irritations, and absenteeism among the workforce was excessive. Careful examination of the environment had failed to identify any significant contaminants in the air. The situationwas similar to the SickBuilding Syndrome in office buildings.
Airtightness deficiencies of building envelopes and weaknesses in the ventilation systems can disrupt the operation of heating and ventilation systems. This can lead to an insufficient level of air quality and higher energy consumptions. In order to assess the performances of buildings and ventilation systems, CSTB has designed and developed different experimental devices for field testing. In a first step, an equipment was produced to measure the envelope air leakage. This apparatus is mainly used for research purposes.
Air extraction in the kitchen is an essential element in all ventilation strategies for dwellings. This can be done by natural ventilation or mechanical extraction. In practice, the use of mechanical kitchen hoods is very common in Belgium. As part of a research carried out for the Belgian IWONL/JRSIA, the laboratory for Hygrothermics and Indoor Climate of BBRI carried out measurements to evaluate the efficiency of kitchen hoods. The test procedure applied at BBRI is a mix-up of two existing standards.
The new building and HVAC technology was used when an EBES multistorey residential building was built in Helsinki. In the EBES system the building structures are used as an installation space for the heating, piping, ventilation and electrical systems. Building structures are also used as a storage for heating and cooling energy. The main objectives of the overall EBES system are to improve the indoor air quality and energy economy and at the same time to improve the quality of the construction process and reduce costs.
Draughts due to air inlets are one of the problems to be solved for improving the global performance of mechanical ventilation systems. The CSTB full scale test cell "EREDIS" has been used to quantify draughts risks due to air inlets by measuring air temperatures and velocities with known boundaries of wall temperatures and fresh air. The results allow to improve the design of these inlets and to give advices for a better use in residential buildings. Works are now going on for comparing the experimental results to the ones calculated with a CFD code.
This report presents the results from the registration throughout a month of relative humidity, temperature and outdoor air exchange as well as the concentration of carbon dioxide in each room of an inhabited single family house, in which all rooms are ventilated by a mechanical balanced ventilation system with variable air volume. The outdoor air rate is controlled by the relative humidity, which is kept on a value adequate to reduce the living conditions for house dust mites and prevent condensation on the indoor surfaces of the building.
At present, in France three quarters of new housing is fitted with a mechanically controlled ventilation system (MCV). In the last twenty years this type of ventilation system has progressed considerably, notably because of the help given by energy management policies in the housing sector
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