The ventilation rate in a building depends on many things, one of which is the air temperature. The air temperature in turn depends in part on the ventilation rate. The effects of this relationship are generally overlooked in both thermal and ventilation models. To study this effect a model has been developed which integrates the models GAINE and SILONA developed at CSTB. This allows the prediction of the natural ventilation rates caused by the actual temperatures in the building.

This report presents the results from the registration throughout a month of relative humidity, temperature and outdoor air exchange as well as the concentration of carbon dioxide in each room of an inhabited single family house, in which all rooms are ventilated by a mechanical balanced ventilation system with variable air volume. The outdoor air rate is controlled by the relative humidity, which is kept on a value adequate to reduce the living conditions for house dust mites and prevent condensation on the indoor surfaces of the building.

Draughts due to air inlets are one of the problems to be solved for improving the global performance of mechanical ventilation systems. The CSTB full scale test cell "EREDIS" has been used to quantify draughts risks due to air inlets by measuring air temperatures and velocities with known boundaries of wall temperatures and fresh air. The results allow to improve the design of these inlets and to give advices for a better use in residential buildings. Works are now going on for comparing the experimental results to the ones calculated with a CFD code.

For more than 20 years, energy recovery systems have been operated successfully in European countries in comfort and industrial ventilation systems in order to reduce the heating and cooling capacity as well as to reduce the annual energy consumption for the treatment of supply air. By 1991 the total heating capacity of all installed energy recovery systems in Europe was about 60.000 MW and the equivalent of the annual energy savings was about 10 million tons of oil.

The new building and HVAC technology was used when an EBES multistorey residential building was built in Helsinki. In the EBES system the building structures are used as an installation space for the heating, piping, ventilation and electrical systems. Building structures are also used as a storage for heating and cooling energy. The main objectives of the overall EBES system are to improve the indoor air quality and energy economy and at the same time to improve the quality of the construction process and reduce costs.

Air extraction in the kitchen is an essential element in all ventilation strategies for dwellings. This can be done by natural ventilation or mechanical extraction. In practice, the use of mechanical kitchen hoods is very common in Belgium. As part of a research carried out for the Belgian IWONL/JRSIA, the laboratory for Hygrothermics and Indoor Climate of BBRI carried out measurements to evaluate the efficiency of kitchen hoods. The test procedure applied at BBRI is a mix-up of two existing standards.

Good indoor air quality in buildings becomes such a major concern that new design recommendations emerge in many countries (USA, Nordic Countries,...). Improvement of the interior environment should not beat the expense of higher energy consumption. Heat recovery systems are one appropriate answer to this challenge. However, additional energy savings could be achieved by applying demand controlled ventilation when the internal loads vary significantly. A CO2 controlled ventilation system has been installed in a conference room with high variable occupancy in mid 91.

Experiments were carried out in four naturally ventilated offices to measure the indoor environmental parameters such as air velocity, turbulence intensity and air temperature at three vertical levels, Air change rates for various indoor and outdoor climates were detetmined. The concentration of carbon dioxide in the room was monitored. Subjective assessment was made to evaluate the thermal comfort and indoor air quality in the offices. The effect of opening windows and doors on the indoor comfort conditions was also investigated.

During the last decade several surveys in Sweden have indicated that the indoor climate in existing schools is unsatisfactory, therefore a thorough project was carried out in Växjö). The indoor climate was investigated in three schools during 1989. Detailed measurements were made of ventilation (e.g. rates, air exchange efficiency), indoor air quality (e.g. CO2) and thermal comfort (e.g. air velocity). The main results were: high indoor temperatures, low air velocities and high concentration of CO2. Improvements were made in all three schools during 1990.

The study deals with the theoretical and experimental simulation of gas leaks in buildings. Such simulations may provide helpful information about the flow characteristics and dangerous concentrations as a function of the ventilation system (if any), the geometrical features and the thermal constraints on the room, and eventually about the positioning of gas monitoring devices.