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.

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 U.S. Environmental Protection Agency is seeking to improve the thermal quality of newhomes, most of which are being built in the sunbelt by large building development companies.Low-infiltration production (tract) homes need ventilation systems that satisfy the low-costpriority of the builders as well as the safety, health and low operating cost expectations ofhomeowners.

The main goal of IEA Annex 27 "Evaluation of ventilation systems" is to develop tools toevaluate ventilation systems in an objective way in terms of indoor air quality, energy,comfort, noise, life cycle costs, reliability and other building related parameters.To check the developed tools some measurements in real dwellings are necessary. Thedevelopment of the tools is in its final stage. During the AIVC conference some of these toolswill be presented. The indoor air quality tool is not yet ready.