The energy saving practice of stopping ventilation systems at night may reduce the daytimeair quality. Sorption phenomena where pollutants absorbed at night are reemitted during theday and the general slower removal of pollutants at the reduced average ventilation rates willcontribute to the deterioration of air quality at intermittent running systems. The purpose ofthe study was to investigate the impact on construction product emission during the day fromreduced ventilation rates at night. Experiments were performed in three small-scale chambersof Climpaq type with dilution systems.
Over the last decades, a great importance has been given to thermal insulation, in technological designing of building envelope. Lately, a basic requirement of indoor air quality, strictly related to ventilation control strategies, has been highlighted. Then, it is necessary to evaluate correctly, during the design phase, the air permeability of enclosures through validated methods, to assess new technologies through laboratory tests on prototypes and finally to verify real performances through on-site testings.
Rooms with high windows are likely to have comfort problems caused by cold airdowndraught, which are usually solved by placing heating appliances underneath thewindows. In the city of Zug, Switzerland, a highly insulated educational building with aconcrete core system for heating and cooling is planned. The purpose of our investigation wasto find out whether any measures are necessary in this building to compensate the effects ofdowndraught in the occupied zone. Special attention has been paid to the effect of passivemeasures like air flow obstacles or openings in the window sill.
Usually, the performance of fan-coils is defined and measured in the laboratories only through thermal quantities. However, comfort conditions within a room depend also on the air flow pattern determined by the appliance. Therefore, an experimental procedure to evaluate the fluid dynamic performance of fan-coils has been developed.
The paper deals with the differences in the air quality between that perceived by the occupants (breathing zone) and that in the occupied zone as a whole. An environmental chamber with a displacement ventilation system has been used to carry out the measurements with the presence of a heated mannequin and heat sources. Measurement of the age of air distribution in the chamber were carried out for different room loads. It has been found that the perceived air quality for a seated mannequin is about 40% better than the average value in the occupied zone.
This paper discusses the experimental study of direct delivery of cold air into a full scale environmental chamber using different diffusers, i.e. a multi-cone circular ceiling diffuser, a vortex diffuser and a nozzle type diffuser. Comparisons have been made of the following: mean flow patterns, temperature distribution and condensation risk. The vortex diffuser exhibits a higher induction effect than that of the nozzle type diffuser. However, the air speed generated by the vortex diffuser is generally lower than that of nozzle type diffuser.
Most of the existing emission models developed from small-scale chamber tests assume complete mixing in the chamber throughout the test period. This paper examined this assumption using a Computational Fluid Dynamics (CPD) model. The model simulated the three-dimensional air velocity profiles and Volatile Organic Compound (VOC) concentration distributions from wood stain in a well-designed mixing chamber of 1.0X0.8X0.5 m3. The model used measured data to determine the time-dependent voc surface concentrations of wood stain.
A study of air movement and aerosol particle distribution and migration in a ventilated two-zone chamber is presented. The comparisons of average particle concentration decay between numerical results and measured data are generally satisfactory and acceptable. It can be concluded that the particle distribution and migration are mainly influenced by the airflow pattern and ventilation rates.
The Field and Laboratory Emission Cell (FLEC) is a tool for non-destructive emission testing of materials with even surfaces. Measurement of air velocities inside the cell showed an inhomogenous flow field with a high-velocity area around the inlet axis and an area of comparatively low air velocities perpendicular to the inlet axis. These results suggest that punctual emission sources may lead to different VOC-concentrations depending on the position of the source.
Login