The paper presents examples of hybrid ventilation and control strategies in office and educational buildings from the IEA ECBCS Annex 35 HybVent case studies. The purpose is to extract the lessons learned in the case studies about the control strategy used. The conclusions are that in each building project the control strategy has to be carefully designed and operated, not only in relation to the general building design and the ventilation systems in the building, but also in relation to occupants habits, reactions and expectations to indoor climate and comfort.
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.
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.
Update on the IEA ECBCS Annex 35 project on hybrid ventilation systems. Discusses hybrid ventilation air flow process, climate data and air flow around buildings, pressure distribution on building surfaces, air flow characteristics of openings, air flow characteristics for other elements, air flow in and between rooms in a building, and air flow process for whole systems.
Discusses the new concept of hybrid ventilation, and the objectives of IEA ECBCS Annex 35 research in this area. Important areas of research are the development of control strategies, theoretical and experimental studies, the development of a decision tool, the implementation and demonstration of hybrid ventilation, reporting and expected results.
The international project Annex 35 "Hybrid ventilation in New and Retrofitted Office Buildings was accepted by the IEA at the Energy Conservation in Buildings & Community Systems Executive Committee Meeting in Washington June 1 997. The first year, starting August 1 1997, was a preparatory year and the four year working phase started August 1 998. The Annex have participants from 1 5 countries: Australia, Belgium, Canada, Denmark, Finland, France, Germany, Greece, Italy, Japan, Norway, Sweden, The Netherlands, United Kingdom and USA.
Current thermal comfort standards and the models underpinning them purport to be equally applicable across all types of buildings, ventilation systems, occupancy patterns, and climate zones. A recent ASHRAE-sponsored research project (RP-884) critically evaluated this by statistically analysing a large thermal comfort field research database from 160 buildings scattered all over the would (n=22,000).