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.

Although several investigations on how to design airtight buildings have been performedand the results furthermore have been published, many designers and contractors are stillunaware of this knowledge. Therefore, the aim of this work is to collect existing knowledgeand put it together to a practical guide. The target groups are architects, designers, contractorsand building services engineers.This paper is a summary of the report "Good Airtightness - guidelines to architects, buildingdesigners and contractors "published in Sweden during the autumn of 1997 [1].

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.

Continuously rising energy costs, the demand for reduction of CO2-emission and theprohibition of CFC-containing refrigerants create a base for new concepts of air-conditioning(A/C) systems. A primary action must be the prevention of heat consumption and cooling loadby improvement of the building architecture. Additional the efficiency of the A/C process mustbe improved, in order to reduce the energy input.In most cases the target is to replace the dehumidification process, which normally is realizedby refrigerating cycles, by alternative systems.

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.

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.

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.

This research is part of project NATVENT (TM), a concerted action of nine institutions ofseven European countries under the Joule-3 program. It aims to open the barriers that blocks theuse of natural ventilation systems in office buildings in cold and moderate climate zones.Natural night-time ventilation cooling is a very effective means to remove the heat,accumulated in the building fabrics during office hours. Moreover, it requires no energy at all.Cooling with natural ventilation has it limits; more than 6 air changes per hour have no morecooling effect.

In this paper the energy impact of natural cross ventilation is examined conducting a set of crossventilation experiments in a well insulated apartment of a 5-storey building. The experimental resultscompared with simulation results derived from the combined use of the multizone air flow modelCOMIS and the thermal model Suncode.A 24-hour lasting natural cross ventilation experiment was conducted, to monitor thermal comfortventilation mainly during the day and night time cooling ventilation.