English

Nowadays it is rather common with demand controlled ventilation in public buildings and offices. The purpose of demand controlled ventilation is to adapt the ventilation to the varying needs of the occupations. In dwellings it is rather unusual with demand controlled system. The main reason for that is the high investment cost for the system. The outdoor air used for ventilation in dwellings is therefore not effectively used. For example in a mechanical exhaust ventilation system 50 % of outdoor air is leaving the house without being used of the people.

The installation of packaged heat recovery ventilation (HRV) systems has recently become common practise in new homes in Canada. Despite improvements in product quality and reliability, HRV systems are only capable of providing safe, continuous, efficient and effective ventilation if homeholders have a understanding of the basic operation and maintenance procedures and the system's interaction with other house systems. Furthermore, homeholders must be able to perceive the value of HRV systems if they are expected to operate them.

The work concentrated on estimating the effects of building leakages and terrain parameters on the air infiltration. The analysis was performed mainly using a multi zone airflow model Movecomp with which the building and its ventilation system could be described in detail. The computations were performed for a flat in a 418-storey building. The highest infiltration occurred in an untight two-facade flat in open terrain. The calculations gave valuable information on the effect of the location of the leakage.

ASHRAE has developed a draft of a measurement standard, Standard 129, entitled "Standard Method of Measuring Air Cliange Effectiveness." This standard defines a method of measurement for measuring air change effectiveness in mechanically ventilated spaces, and provides a discussion of how the values of air change effectiveness may be used to demonstrate compliance with ASHRAE 62-1 989.

The use of IR detectors to steer the ventilation is in principle an attractive approach for optimising the ventilation according to the occupants needs. In order to evaluate the performances under real conditions, one of the BBRI office buildings in Limelette (some 31 offices with in total 51 persons and a variable occupation load) was equipped with a mechanical supply ventilation system in which each terminal is controlled by an IR detector.

The IEA Annex 27, "Evaluation and Demonstration of Domestic Ventilation Systems" is aiming at developing tools by using the most developed computer models and equations available including modul development. Before staring up all the simulations an in depth review of the variables influencing the evaluation of a ventilation system have been done and a report is to be published. All parameters are needed to be mapped so that realistic assumptions can be made for the simulation phase.

Airtightness and infiltration rate measurements in office and other commercial buildings have shown that these buildings can experience significant levels of air leakage [1,2]. The energy impact of air leakage in U.S. office buildings was estimated based on the analysis of a set of 25 buildings used in previous studies of energy consumption [3,4]. Each of these buildings represents a portion of the U.S. office building stock as of 1995.

A breakthrough in ventilation research was made once it was realized that ventilation principles based on mixed flow patterns are not optimal and that further energy savings can be achieved if an alternative technique could be developed. Several researchers, particularly in the Nordic countries, have shown by theoretical studies that replacing mixed ventilation flow by displacement flow increases ventilation efficiency. This also results in decreased air supply volumes and thus decreased energy requirements. In addition, lower air velocities may reduce problems of comfort and noise.

A preliminary study of the potential for using central forced-air heating and cooling system modifications to control indoor air quality (IAQ) in residential buildings was performed. The main objective was to provide insight into the potential of three IAQ control options to mitigate residential IAQ problems, the pollutant sources the controls are most likely to impact, and the potential limitations of the controls. Another important objective was to identify key issues related to the use of multizone models to study residential IAQ and to identify areas for follow-up work.

To achieve acceptable indoor air quality (IAQ), ASHRAE Standard 62-1989 recommends the use of the alternative IAQ procedure. The IAQ procedure can treat both constant-volume and variable-air-volume (VAV) with constant or proportional outside airflow rates. The relationships in Appendix E of the standard must be used in conjunction with the IAQ procedure to directly calculate indoor air contaminant concentrations in an occupied space.