PR1997

A model for the application of probabilistic methods is the estimation of heat loss caused by convection and heat conduction through the material is developed. Temperature difference (delta T) between inside and outside of a building, air change rate (ACH) and coefficient of thermal transmittance (U-value) of the building structure are treated as random variables. The mean value and standard deviation of heat loss are estimated for different parameters of distribution for temperature difference, air change rate and thermal transmittance.

This study aimed to research the airtightness of the building envelope in apartments before and after renovation. Measurements were carried out in three apartment buildings. One to four apartments were examined in each building. Typical renovation measures included changing the windows and refurbishing the interior surfaces. In some cases the ventilation system was renovated as well. No special emphasis was placed on the sealing of the envelope. The airtightness of the apartments increased in most cases. There were, however, apartments that became leakier during the renovation.

This paper discusses summer cooling of buildings by means of natural ventilation. Computational fluid dynamics is used to predict the ventilation rate in a room with a Trombe wall. The effect of Trombe wall insulation on the room thermal environment is investigated. It is shown that to maximise the effect of ventilation cooling, the interior surface of a Trombe wall should be installed.

The year-round climate of Taiwan is warm and humid. Apart from the hottest months in summer, there are four months suitable for nocturnal ventilation to acquire indoor cooling. The urban Taiwanese apartments are small due to the limited usable land.

Temperature and cooling demand in a room summertime are influenced by numerous factors,like internal gains, ventilation, solar gain, behaviour of occupants, thermal inertia of the roomand outdoor conditions (climate).The thermal environment and cooling demand summertime are often analysed using detailedcomputer programs, which take into account the factors mentioned above (among others).Often the overview, transparency and some of the physical insight is lost using these advancedcomputer programs.In a predesign phase of a project it is preferable to do simple calculations of the thermalbeha

A method for estimating the reliability of mechanical ventilation systems in dwellings hasbeen developed. The analysis is based on component level reliability models interconnectedby so called fault-tree schemes. A simplified model for maintenance is included. Theanalysis procedure is applied on an central exhaust ventilation system and on a central supplyand exhaust ventilation system with heat recovery. For each system, three different qualitystandards have been defined and combined with three levels of maintenance. Work has alsobeen done on collecting relevant input data, e.g.

The paper outlines the value of roof intake air ducts to serve largely passively ventilatedand cooled buildings in urban areas. This approach improves air quality, reduces noisepollution and enhances security.A diagrammatic representation of night cooling using this approach is given followedby a description of experimental work at the Bartlett.

One of the first sorption-supported air-conditioning systems ("Desiccative Evaporative Cooling Systems") in an industrial building in Germany was installed in a printing office in Waiblingen, a town in southern Germany. The circumstances for such a system showed to be optimal, as the printing office is equipped with its own co-generation system delivering a considerable amount of waste heat. The experiences made with the system in the hot and humid summer of 1995 were very positive.

Natural passive stack ventilation (PSV) consumes no power and so produces no harmfulemissions, has no running cost, no noise of operation, requires little maintenance and becauseit involves no moving parts, operation is reliable. However, virtually all PSV systems aredesigned and constructed without incorporating heat recovery, leading to wasteful heat loss.The goal of the research reported here, is to develop a passive stack ventilation system withheat recovery for use in naturally ventilated buildings.The heat recovery unit is based on the heat-pipe principle.

In the present paper a model for steady-state thermal analysis of ventilated and unventilated light rook is proposed. The aim of the work is tostudy the influence of thermo-physical and geometric parameters of the roof and boundary conditions (solar radiation) on the entering heat flowand the temperature distribution within the roof structure.