air conditioning

Tests have been performed on several ceiling air diffusers supplied with low air temperatures (6 to 16°C - 90% humidity) to study water vapour condensation on diffusers surface. Results show that a supply air temperature of 11°C avoids most of condensatio

Flow and heat transfer calculations have been operated in a typical office room equipped with a displacement ventilation and a chilled ceiling system. Results show quasi-periodic flow when the values of internal thermal loads are high. They also show lateral oscillations of the plumes above heat sources which create after impact on the cold ceiling recirculating flows in the room.

States that existing standards and models are not sufficient to characterise the satisfaction and pleasantness for end-users which is provided by heating or air conditioning. The project described here was devised with the aim of using sensory evaluation techniques in the design of HVAC systems. A dual evaluation is used for sensory evaluation in the food cosmetics, phone and automotive industries, comprising of sensation measurements carried out be a small panel of trained expert assessors and preference studies performed by a large panel of representative consumers.

States that the PMV model is in good agreement with high-quality field studies in buildings with HVAC systems, located in cold temperate and warm climates, which were studied in both summer and winter. Occupants may sense the warmth in non-air conditioned buildings in warm climates as being less severe than the PMV prediction, probably because of low expectations or because too high an estimate of metabolic rate. Introduces an extension to the model which includes an expectancy factor to be used in non-air conditioned buildings in warm climates.

Gives a report on thermal comfort and IAQ studies of an under-floor air-conditioning (UFAC) system in a hot and humid climate. In order to predict the airflow pattern of the supply air jet and to determine the occurrence of thermal stratification in the office room, thermal comfort parameters were measured at predetermined grid points within an imaginary plane. The authors also used Fanger's thermal comfort index to detect the occupants' thermal sensation, and measurements were made of the concentration levels of dust and carbon dioxide.

Air conditioning systems are often held to have effects upon the workforce. This research tried to assess whether continuous exposure to air-conditioning during working hours had any observable effect on health or not. A comparison was made of absence due to sickness recorded by the employers' doctors over two years in two groups of workers employed in similar jobs in the French National Electric and Gas Company in Western France. One group spent most of their time in air conditioned offices but the other worked in a natural atmosphere.

Sensitizations to fungi that can be isolated when the fungi are removed from air conditioners are often shown by people suffering from various symptoms while in air conditioned rooms. It was shown that by using specific challenge tests fungal spores in air conditioners can give rise to allergic symptoms. The specific therapy prescribed for these reactions was hyposensitization. After this therapy, more that 70% of the patients could live and work again in air conditioned rooms without developing symptoms.

This study compared the prevalence of sick building syndrome among two groups of public service workers in Perugia, central Italy. 525 were employed in an air conditioned building with fan-coil units in every room and 281 in three naturally ventilated buildings. All the subjects completed a questionnaire about work-related SBS symptoms with an occupational medicine specialist.

This research studies the effects of air conditioning on blood pressure and the heart rate. It is based on studying the blood pressure and pulse of 32 young healthy Nigerian volunteers after they had been in an air-conditioned room from between 60 and 90 minutes. The same measurements were made under the same conditions with the air-conditioning switched off. The mean systolic blood pressure (SBP) was 115.3 +/- 11.5 mm Hg with air conditioning (AC) and 108.5 +/- 10.1 mm Hg without air conditioning. This difference was statistically significant.

Describes a study which was aimed at investigating whether relations between symptoms of sick building syndrome and measured environmental factors existed within state of the art air conditioned buildings with satisfactory maintenance programmes expected to provide a healthy indoor environment. Studied five buildings, using a questionnaire followed by a detailed environmental survey.