PR1997

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.

A difficulty when designing natural ventilation in office buildings is the lack of simple designtools.In order to be able to predict natural ventilation air flow rates and indoor air temperatures atthe design stage, a computer model has been developed within the EU-JOULE projectNatvent (TM). The program is an integrated model with a thermal and an air flow modelcoupled together.

Due to the lack of proper sensors for odours, the odour concept, involving the unitsolf and decipol, is of very little practical use with respect to automatic control of VAVsystems. However, the decipol level in a room may be predicted from the concentration ofCO2 and the amount of fresh air supplied. By using the CO2 level as a decisive variable ofthe occupant load within the room, the actual air quality (decipol level) can be predicted.Once the decipol level is known, it is compared to a given set point, thus enabling thecontroller to alter the air flow rate accordingly.