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The Paper deals with numerical computations, carried out, in order to predict the effects of natural convection on the thermal performance of porous material. In this paper the effect of natural convection in a horizontal porous layer will be discussed. The study of the above configuration is essential to understand the functioning of insulation of the type used in attics. The influence of natural convection on the thermal properties of mineral wool, loose-fill insulation, insulation made of small and large polystyrene balls are studied.

The necessity to provide and maintain high cleanness of air in the rooms of the highestcleanliness classes requires a proper adaptation of selection and designing methods for airfilters. The level of air cleanliness for such rooms is defined numerically by the determinationof the permissible number of dust particles whose diameters are equal or higher than the givenlimit values.

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.

A secondary analysis of the Dutch prevalence study by Zweers et al shows that office buildingswithout artificial cooling and with operable windows have a lower risk for health symptoms andcomfort complaints than office buildings with artificial cooling and sealed windows. Temperature ,simulations of various office buildings show that in the Dutch climate zone thermal comfortduring summer conditions is secured without the use of artificial cooling if a number of essentialdesign criteria are met.

Split-system air conditioning is increasingly usedapplications, owing to its low cost and installationboth for residential and commercialease. The indoor split-system unit iscommonly of the wall-mounted type and, due to its dimensions and position, very often itgives rise to appreciable air velocities and temperature gradients in the occupied zone of theroom. This work reports and discusses some experimental data collected in a test room withwall-mounted indoor unit, under different operating conditions.

The ventilation engineer's plan at the design stage could be influenced by many factors. It may also be different from the requirements for the final users of the spaces. In case of open-space design, which is getting popular due to its flexibility. It is more difficult to provide adequate ventilation to control the indoor air quality. Specially, when partitioning of the space is employed.

Recently well-insulated and well-airtightened houses are increasing in Japan. Those houses havesome problems of air quality because of formaldehyde from construction materials. Ventilationsystems have possibility to solve these problems. The authors have developed a simulation programfor designing building elements, equipment elements to keep balance among comfortabletemperature and humidity, good air quality and energy conservation. The effects of some ventilationsystems in multiple dwellings are revealed by the developed simdation program.

The objectives of thisinvestigation were to examine the dynamic water vapour sorption offurnishing materials and to compare the experimental results withpredictions obtained from the Moisture Admittance Model. Dynamic sorption measurementswere carried out for common building materials. The measurements were made by placingspecimens of the materials in a humidity chamber and varying the ambient humidity between46% and 90% RH at constant 22C. The weight of the specimens was monitored in situduring this procedure.

There is a growing demand for buildings to have a high indoor air quality environment. Twoof the main elements that contribute to this quality are temperature and air distribution withinthe occupied space. In modern office buildings particularly in hot climates, care must be takento design the most economical air distribution system that provides comfort for the occupants.There are many techniques available to predict the air distribution patterns in the space atdesign stage, but these are often not very accurate.

Few detailed comparisons of modeled ad measured pollutant concentrations in multizonebuildings have been published. The COMIS air flow and contaminant transport modelpermits simulation of the effects of building and HVAC operation, as well as the influence ofthe local meteorology, on air flows within the building. We have recently used this model tosimulate the release of a gas-phase tracer in a three-story, multi-room building located atDugway Proving Ground, Utah, USA.