outdoor air

States that to control humidity it is necessary to remove moisture load from ventilation air. The combination of increased ventilation and air conditioning brings more humidity in from outdoors with a greater chance that condensation will occur on surfaces chilled by the cooling system. Suggests that rooftop equipment for cooling is frequently oversized. Considers the nature and dimensions of the moisture loads.

This paper presents a Chinese approach to ventilation and air conditioning, which are important measures needed to improve the indoor air environment of a building. They are important because improper design of a system may degrade the indoor air environment rather than enhance it. This is a situation that might be called sick air conditioning. Also, in circumstances where the outside air is heavily polluted air treatment is necessary to avoid worsening the indoor environment.

When natural ventilation is being used, the quality of the air inside a building depends on the quality of the outside air. What is the outside air quality trend in the urban environment and what are the forecasts for the future? How is air quality measured and what are the expected European standards for outside air quality in 2010? The implications of these developments for the hybrid ventilation of buildings close to roads and motorways are explained.

The CIBSE is to publish new guidance on environmental criteria later this year. This includes new material on Indoor Air Quality which provides a strategy for minimising indoor air quality problems in buildings and improving the effectiveness of outdoor air supply in controlling indoor pollution. This Chapter explains the reasons for this approach and the basis for the guidance given.

We analyzed 1994 sick leave for 3,720 hourly employees of a large Massachusetts manufacturer, in 40 buildings with 115 independently ventilated work areas. Corporate records identified building characteristics and IEQ complaints.

Perceived air quality, Sick Building Syndrome (SBS) symptoms and productivity were studied in a normally furnished office space (108 m3) ventilated with an outdoor airflow of 3, 10 or 30 L/s per person, corresponding to an air change rate of 0.6, 2 or 6 h-1. The temperature of 22°C, the relative humidity of 40% and all other environmental parameters remained unchanged. Five groups of six female subjects were each exposed to the three ventilation rates, one group and one ventilation rate at a time. Each exposure lasted 4.6 h and took place in the afternoon.