Ventilation needs in dwellings must be determined on the basis of both requirements to theindoor air quality and necessary control of moisture conditions. As a first step towardsdevelopment of energy efficient ventilation strategies for demand controlled ventilation infuture dwellings theoretical analyses comprising a literature study and mathematicalsimulations have been carried out.

In order to assess the real performances of different demand controlled ventilation (DCV)systems, two of them were installed in meeting rooms of an office building.The first system is controlled by movement detection on terminal units and has been installedin a small meeting room which is regularly used.The second system is controlled by CO2 detection and frequency variation on fan. It has beeninstalled in a large meeting room (30 persons seated, up to 50 persons standing).The systems have proved to be energy saving with correct CO2 levels.

In this study, we investigated the indoor air quality (IAQ) in classrooms with exhaustventilation systems and in naturally ventilated classrooms. In the latter, we found peak CO2-concentrations of more than 4000 ppm. 1500 ppm was exceeded during 40 to 86% ofteaching time, dependent on class size. The windows were opened rarely in winter which ledto low mean air exchange rates of 0.20 0.23 h^-1. The operation of mechanical ventilationsystems improved IAQ considerably. Peak CO2-concentrations decreased to less than 2500ppm. 1500 ppm was exceeded for only 7 to 57% of teaching time.

The development of guidelines for performance based innovative mechanical ventilationsystems in residential and commercial buildings is included in the European Commissionproject TIPVENT Towards Improved Performances of Mechanical Ventilation Systems.The overall aim of TIPVENT is to promote improved performances of mechanical ventilationsystems and the introduction and implementation of innovative designs. The development ofperformance oriented procedures for designing, commissioning and maintaining mechanicalventilation systems plays a key role in the project.

A hybrid ventilation system is a two-mode system that can automatically switch between passive and mechanical mode at different times of the day or seasons of the year. Some ventilation systems, including the hybrid system, have been set up in a full-scale test house constructed in Tohoku University, Japan to assess their performance. In this paper, the performance of each system is described by giving measurement results.

This paper aims to identify major characteristics of hybrid ventilation systems, whereby a clear distinction is made between ventilation for Indoor Air Quality control and ventilation as part of a strategy for control of thermal comfort in summer. The aim is to identify the major differences between the various approaches and to develop some kind of rationale. Various building projects are used as illustration for the classification.

Within the EC-JOULE project "AIRLIT-PV", a new facade unit, integrating ventilation, daylighting, solar protection, intelligent local control and photovoltaic power, has been developed and is under evaluation by means of performance testing at four different test sites in Europe, both in test cells and in occupied buildings. This paper will summarise an extensive market survey, describe the shape and function of the unit and report on the first findings from the performance testing of the units. The ventilation performance will be emphasised.

The target in this study was to decrease the energy use for transportation of air (fanenergy) with a factor of three. Two real systems composed of existing componentswere constructed in a laboratory; a mechanical exhaust system and a balanced system.The flow rates through the systems were set at values according to the Dutch BuildingRegulations. This situation is called the reference situation. A number ofimprovements have been tested and studied.

A new method for providing ventilation in large enclosures, which utilizes the principle of 'selective withdrawal' of contaminants while ensuring energy-efficiency and allowing a better use of space, is presented in this study. The concept is based on dividing the enclosed space ventilation-wise into separate zones using a combination of horizontal partitions by stratification and vertical partitions by temporary walls. This gives a high degree of flexibility in the use of available space.