The performance of various kinds of ventilation systems (mechanical supply, mechanical exhaust, mechanical supply and exhaust, crawl space supply and hybrid exhaust) was evaluated in a full-scale test house during heating period. The concentration method (SF6 tracer gas) was used to measure the ventilation air flow rates to each roomntilation. Results of experiments are presented, showing the air distribution between floors and rooms.

This paper presents a numerical study of hybrid ventilation in densely populated multi-storey urban apartment units. Seven cases are presented with variation of parameters such as outdoor air temperature, apartment floor heat source and built-in fan power : 3 cases with natural ventilation and 4 with hybrid ventilation. An analysis of thermal comfort and pollutant transport is made from the calculation results.

Results of IEA ECBCS annex 35 Hybvent case studies about the control strategy used in buildings with hybrid ventilation are summed up in this paper : it is easy to design a suitable control strategy for hybrid ventilated cellular offices, but it is much more difficult for the landscapes offices mainly due to automatic central control of windows.

This paper demonstrates that the distribution and area of ventilation openings affects significantly the air flow rates in a hybrid ventilation system.

The use of a hybrid cooling system using radiant cooling panels with wind-induced cross ventilation is described in this paper. Its performance is compared to the hybrid system using underfloor air-cooling. The radiant cooling panels system appears more energy efficient and brings more thermal comfort than the under-floor air cooling system.

This study was undertaken in IEA ECBCS Annex 35 to model a hybrid-ventilated room and to implement control strategies. An experimental cell was designed and simulations were performed after having adjusted the thermal models to experiments. The hybrid ventilation proved more performant than traditional ventilation systems.

Sixteen countries world wide have participated to this international programme (IEA ECBCS Annx 35) running from 1998 to 2002 about "Hybrid ventilation in new and retrofitted office buildings" . All results of the project are published in a booklet and a CD ROM. They have also be published onthe AIVC CD (see AIRBASE recording number 14923).

A poor ventilation in buildings costs considerable amounts of money for hospitals and businesses.10 % of hospital acquired infections are directly due to an airborne route. The quantity and the quality of air supplied is important but also the way it is introduced into spaces. A change of the Wells Riley equation (establishing a link between the likelihood of infection, the infective agent production rate, the exposure time, the pulmonary and room ventilation rate) is proposed to take into account ventilation eefectiveness.

This paper gives the results of a field study in Danish office spaces with displacement ventilation systems. Draught was identified as a serious problem. Half of the 227 occupants were not satisfied with indoor air quality. Occupants counteract draught discomfort in blocking air supply diffusers or asking the maintenance staff to increase the supply air temperature. So a very careful design for displacement ventilation is required in order to perform satisfactorily in practice.

Thermal comfort for 227 occupants in 8 office buildings with displacement ventilation was investigated. The occupants' thermal sensation was close to the predictions by the PMV index. The main conclusion is that draught is the major local discomfort factor for the occupants, mainly at lower leg. The effect of vertical temperature gradients on occupants local discomfort did not appear as evident.