This field study was organised to track differential pressure relationships in critical care units of a metropolitan hospital. Maintaining design pressure balances is essential to control risk of airborne disease transmission within these units. the pressure differentials that exist between two patient isolation facilities (positive and negative) and their surrounding spaces were monitored continuously for one week.

Residential ventilation systems can be categorized as supply, exhaust, or balanced systems.This effort focused on establishing a design methodology for central-fan-integrated supplyventilation systems. Air flow measurements were taken for 7.6 m lengths of 12.7 cm through22.9 cm diameter flexible ducts, with a 15.2 cm wall-cap, at duct pressures of -10 Pa to -120Pa. Using these measurements and field experience, a five-step method was developed as aguide for sizing and installing the ventilation system.

The HVAC components are usually made of galvanised sheet metal which is covered by a corrosion protection and also lubricant oils are used in machine tools in manufacturing of the components or ducts. The aim of this study was to test and develop a consistent method to determine oil concentrations on component surfaces. Two swiping methods and a filter contact method were tested. In al of them the analysis based on IR-spectrometry. The results show that oil concentration is quite high and unequally distributed on the surface of the sheet metal containing corrosion protection oil.

Different ground-coupled earth-to -air heat exchangers have been constructed in many residential and occupational buildings in Switzerland to precool or preheat the incoming air. Many technical and energetic facts favour such systems. The objective of this study was to determine if microbial growth occurs within these tubes and if adverse health effects must be considered. The results show large reductions in viable bacteria and spore concentrations along the tubes and very low concentrations in the supply air compared to the outdoor air.

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.

Air handling units do not always function as planned: airflow rates are often larger than required, the recirculation rate is not at its set-point value and parasitic shortcuts sometimes decrease dramatically the ventilation efficiency. A dedicated diagnosis, based on the tracer gas dilution technique can easily detect such dysfunction, and help to cure the defects.

The role of outdoor spaces’ design as well as the mutual correspondence among urban microclimate, indoor air climate and air quality, have been specifically investigated for the case study of the Central Athens Area. A comprehensive urban design proposal

Air exchange rates of ten residential buildings were measured according to ASTM-E741-83 using SF6 as a decaying tracer. Air exchange rates were also predicted based on the characteristics of the HVAC system, openings (such as windows), leakage areas, pertaining average wind speed, average indoor/outdoor temperature difference and wind and stack coefficients. It was found that measured air exchange rates were higher by 34% than those predicted if the literature coefficients were used.

The feasibility of designing ventilation routes in the house with passive ventilation system is investigated using the numerical experiments and the measurements on its ventilation rates and indoor air quality. As a result, the ventilation design using the used-air in the rooms on the second floor is proved to be one of the simplest ways to keep good indoor air quality. And the required airtight level of the house with the ventilation design is lower than that with the general ventilation design where the air is supplied to every room.

Energy-saving improvements in the thermal properties of buildings often have an adverse effect on indoor air quality, leading to risks of structural deterioration. In these cases, the air change rate inside dwellings must be increased while ensuring that flued gas appliances continue to function correctly. The proposed ventilation system is a cross between natural draught and controlled mechanical ventilation. It activates natural ventilation of the dwelling by means of the induction principle.