ventilation performance

The aim of our study was to determine the effect of a cooling jet on performance and comfort in warm office environment. We compared cognitive performance, subjective workload, cognitive fatigue, thermal comfort, symptoms, perceived working conditions and perception of airflow in warm temperature (29.5 °C) in two conditions: with and without the jet. Twenty-nine students participated in the experiment in which a repeated measures design was employed. The jet improved the speed of response in a working memory task with increasing exposure time but did not affect other performance measures.

As newer homes are being built tighter than the existing housing stock, questions have been raised about the concentrations of pollutants of concern in new homes and how mechanical ventilation systems can address this issue. This study measured pollutants of concern in 70 new homes with mechanical ventilation in California, USA and compared the results to a previous study of home without mechanical ventilation. The key pollutants were measured using both time-integrated and time-resolved over a one-week period and included formaldehyde, PM2.5 and NO2.

Research shows that, despite compliance with building codes, residential ventilation systems do not deliver the requested air exchanges in the individual rooms. One of the reasons for this can be found in the way the building codes are composed. In general building codes only specify the minimum ventilation capacity that need to be installed in the various rooms. The actual performance of the ventilation system is left to the market.

We conducted observations of wind velocity profiles above a high-density area in Tokyo, Japan, using a Doppler LIDAR system. Obtained data of the exponent index for the power law, which is commonly used to describe the wind velocity profile, displayed diurnal variation, decreasing in the daytime, which is expected in unstable atmospheric conditions. This paper provides information on the uncertainty in the calculated ventilation airflow rate due to the use of a constant value for the exponent index.

We conducted observations of wind velocity profiles above a high-density area in Tokyo, Japan, using a Doppler LIDAR system. Obtained data of the exponent index for the power law, which is commonly used to describe the wind velocity profile, displayed diurnal variation, decreasing in the daytime, which is expected in unstable atmospheric conditions. This paper provides information on the uncertainty in the calculated ventilation airflow rate due to the use of a constant value for the exponent index.

This research, based on Computational Fluid Dynamics (CFD) analysis, focuses on the wind characteristics and the ventilation performance in the consecutive street canyons produced by various building complex configurations. In this research, the buildings in the street canyon space were distributed in either staggered or normal arrangements and, in consideration of the varying distribution and height of different buildings, high-rise buildings, middle-rise buildings and low-rise buildings were all included.

Ventilation systems are primarily designed for ensuring good indoor air quality (IAQ). However, building energy requirements tend to put demand on reducing air change rates. The assessment of the performance of ventilation systems over long periods has thus become a subject of importance. In this framework, five ventilation systems were investigated for a heating period in a single-family house using a representative occupancy and pollution schedule. This was undertaken using SIMBAD, a combined mass and heat transfer toolbox. This paper compares the different results.

In this present study, annual exceedance probability (AEP) analysis was applied as the method forassessing wind-driven natural ventilation in a street canyon, in which the effects of wind approachingfrom each direction were comprehensively taken into account. In order to evaluate the overallventilation performance in specific domain spaces within the street canyon, local air change rate andaverage kinetic energy were employed to calculate the AEP, instead of using the commonly adoptedvelocity ratio.

Regular maintenance, such as the cleaning of filters, is important for the efficient operation ofresidential ventilation systems. The main objective of this study is to investigate effect of regularmaintenance on fan energy use and ventilation performance by using a test dwelling employingbalanced ventilation system. Experimental tests were directed with simulating the decrease of the airflow rates on terminals. Without cleaning, SFP based on the net air flow rate can indicate by 2.7 times compared with cleaned system.

In France, the performance of ventilation systems in existing buildings is poorly understood today and rarely checked. This article shows how a verification method for ventilation system performance, currently in operation in Sweden, can be applied in France.