This paper reports some findings from IEA ECBCS Annex 35 about wind driven flow through building openings. Wind tunnel studies have been performed on simplified buildings, in order to know if pressure distributions on sealed buildings can be used to predict airflow through facade openings. A new parameter, the catchment area, is introduced by author.

A large opening has first been defined as "an opening where the flow is not fully unidirectional". Then an experimental setup has been installed to conduct wind tunnel measurements on several models of a circular disk, in order to characterize the pressure distribution on simple objects provided both with and without openings.

This paper intends to find a simplified method for the prediction of natural ventilation in a cross ventilated room . This method is based on the use of pressure boundaries instead of the modelling of a larger domain.

This paper reports experiments carried out in a scale model, about possibilities to use buoyancy forces to distribute air and heat through horizontal openings. Water and saline water have been used as operating fluids. This study focuses on the effect of a staircase on the fluid exchange through the horizontal opening. This research is planned to be carried on in a full scale 2 storey-building.

One of the main objectives of this pilot study in a Swedish school was to evaluate the hybrid ventilation system with respect to ventilation, IAQ, thermal comfort, use of electricity for ventilation. The monitoring phase, lasting 2 years, included continuous measurements of outdoor environment, indoor environment, energy use. The monitoring system was integrated with the building energy management system. The reduction in energy use for space heating in the buildings was important and the reduction in use of electricity for ventilation too.

This paper presents the European Research project RESHYVENT with its structure (partners and different work packages) , and its objectives : to develop demand controlled hybrid ventilation systems, including the development of four prototypes of hybrid ventilation systems for specific climates.

The aim of this study was to define whether energy savings and comfortable conditions are achievable along with a reduction or even suppression of the mechanical cooling systems.Three different cooling systems (mechanical standard air conditioning, hybrid cooling, mechanical ventilation cooling) were simulated for a typical US office space under 40 different US climatic data, to calculate energy consumptions.

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.