English

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 France, mechanical cooling is increasingly used in office buildings. This situation isrelated to a demand for a better comfort, the increase of the thermal insulation and internalgains, and the changes in the building design.Nevertheless, in many cases, it is possible to achieve a thermally comfortable environmentby passive means - as thermal inertia, and solar protection of the external envelope - and useof low energy techniques as night or evaporative cooling.

IEA Annex 27 "Evaluation and Demonstration of Domestic Ventilation Systems" has been engaged in developing the evaluation tools for various aspects of their performance. This paper describes the evaluation tool for thermal comfort impact by ventilation systems. The tool is based on the experiment by using inside artificial climate chamber, focusing upon the temperature difference and cold air supply rate into the room. As the evaluation index, the percentage of living space volume where a specified thermal comfort condition is satisfied is used.

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.

Testing was performed in 9 restaurants to identify uncontrolled air flows and pressureimbalances, building and duct system airtightness, building air barrier location, pressuredifferentials, building air flow balance, and ventilation rates. All restaurants are depressurizedunder normal operating conditions, ranging from -1.0 to -43 pascals. Space depressurizationis a function of exhaust fan flow rates, missing or undersized make-up air, intermittentoutdoor air caused by the cycling of air handlers, dirty outdoor air and make-up air filters, andbuilding airtightness.

In this paper the potential of night ventilation techniques is investigated. Extended real scalemeasurements have been performed, in three buildings, under free floating and airconditioned operation. Two of the buildings have been studied by using a theoretical modeldeveloped in TRNSYS [1] software. Simulation results have been validated by using themeasured data. Specific studies concerning the indoor air temperature and the cooling load ofthe buildings have been carried out in order to identifj the influence of night ventilationtechniques on the buildings thermal performance.

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 paper deals with the interzonal air movement in a building, throughhorizontal openings, under natural convective conditions. These airflow phenomena areinvestigated experimentally, through a series of experiments in the stairwell of a full-scalebuilding, using tracer gas technique. The resulting time-dependent concentration evolutionoffers a means of analyzing the flow field. These cases are also simulated by a CFD code, thatuses the finite-volume method and incorporates a low-Reynolds k-E two equation turbulencemodel.

A passive tracer gas technique - the homogenous emission technique was utilised formeasuring the air distribution in a part of an office building with displacement ventilation.Measurements were made during one winter period and one summer period. During thewinter period the ventilation was run continuously, while on/off regulation was used duringthe summer period.

The planning parameters of a cooling system for ventilation, for example the vaporization andcondensing temperatures, heat capacity flow rates, design temperatures and designtemperature differences have a strong influence on the investment and operating costs.The target of this research is to find economically optimized design parameters byminimizing the present value of investment and the operating costs of the cooling system.