System safety analyses of the performance of mechanical ventilation systems - the quantitative approach.

A method for estimating the reliability of mechanical ventilation systems in dwellings hasbeen developed. The analysis is based on component level reliability models interconnectedby so called fault-tree schemes. A simplified model for maintenance is included. Theanalysis procedure is applied on an central exhaust ventilation system and on a central supplyand exhaust ventilation system with heat recovery. For each system, three different qualitystandards have been defined and combined with three levels of maintenance. Work has alsobeen done on collecting relevant input data, e.g.

IEA Annex 27: comparison of performances of different ventilation systems in similar dwellings.

The main goal of IEA Annex 27 "Evaluation of ventilation systems" is to develop tools toevaluate ventilation systems in an objective way in terms of indoor air quality, energy,comfort, noise, life cycle costs, reliability and other building related parameters.To check the developed tools some measurements in real dwellings are necessary. Thedevelopment of the tools is in its final stage. During the AIVC conference some of these toolswill be presented. The indoor air quality tool is not yet ready.

Design of low energy office buildings combining mechanical ventilation for IAQ control and night time ventilation for thermal comfort.

The design of low-energy office buildings requires specific attention to an energy efficient concept for providing good indoor air quality conditions. With this respect, mechanical ventilation shows undeniable advantages: it can be optimally controlled (infrared detection, CO2 control,...), heat recovery is applicable, outdoor noise and pollution penetration can be minimised. Another crucial challenge in low-energy office buildings is avoidance or, if possible, the minimisation of active cooling needs.

Ventilation and air quality in an office building.

The aim of this study is to assess the performance of the mechanical ventilation system and air quality in an office building. The perfluorocarbon tracer (PFT) technique was used to measure air flow in an air handling unit and to estimate flow rates supplied to the office. In order to validate the PFT technique as a viable means of measuring air flow in the mechanical ventilation system, the PFT measurements were compared with measurements made using a pitot-static tube. Air exchange range, ventilation effectiveness and age of air were examined.

Thermal comfort and air quality in three mechanically ventilated residential buildings.

Thermal comfort and air quality were studied in three multi-family buildings located in urban environments. Measurements of air velocities close to the supply devices are presented along with measurements of CO, TVOC, NO and N02. In addition, particle measurements were carried out to check the filter efficiency in one of the buildings (Sl) which is specially designed for people with allergy problems. The total air change rate for this building is higher than for normal residential buildings and three different types of air filter are installed in the ventilation system.

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