humidity

Based on theoretical and experimental tests it was determined that the thermodynamic balancecondition in the working space of air-handling units (AHUs) of heating, ventilating and aircondltioningsystems (HVAC systems) is entirely defined by the humidity potential of thefinal parameters of air and water: @ = constant [1]. This makes it possible to put forward anew thermodynamic method for the analysis and calculation of heat and moisture exchange inAHUs of HVAC systems [2,3].

The present study introduces a humidity control apparatus which can hygienically and automaticlymaintain the appropriate humidity level of indoor air without either a water supply or drainage system.In humidification, the desiccant takes up water vapor from the outdoor air in the adsorption process,and releases it indoors by desorption. Therefore, no water supply is required to humidify. An apparatus havingno water supply is more hygienic, because it does not propagate bacteria and does notscatter the calcium and magnesium salts found in the water.

In residential buildings, air-conditioners are usually operated in intermittent mode. Thisintermittent mode may complicate many aspects of indoor environments. Indoor humidityexcess is a major problem, since humidity excess is associated with biological pollution andformaldehyde emission. This paper reports our monitoring of indoor air temperature andrelative humidity in a real life building in the hot humid Hong Kong climate. These monitoredresults indicate that, in residential buildings, occupants habits in using windows for naturalventilation exacerbate indoor relative humidity excess.

Air flow patterns in rooms can roughly be classified as one of three types: Displacement flow, source flow and mixed flow. Displacement flow in its original meaning is only used in special applications like clean rooms. Mixed flow is generally found in air-conditioned spaces, source flow which is frequently also called "displacement flow" is the usual type of flow in naturally ventilated spaces. This type had become more and more common in air-conditioned spaces in recent years.

House-dust mite antigens are a major contributor to allergic sensitisation. Since temperatureand humidity are crucial to house-dust mite physiology, there is considerable interest inreducing mite populations by controlling the indoor environment.

Three buildings are investigated to study the indoor air quality and the impact of the outdoorair pollution. These buildings, a swimming pool, a school and a nursery are located in anurban area. So, during experimental studies, typical outdoor and indoor pollutants such ascarbon monoxyde, nitrogen dioxyde, carbon dioxyde, and total volatile organic compoundsare monitored. Also, the relative humidity and the temperature are carried out. The analysisallows us to reveal several points.