New Ventilation solutions
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Leader |
Technical University of Denmark, Civil Engineering - Building Physics and Services (DTU – BPS) |
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| Authors |
Christian Anker Hviid, Ph.d., Ass. Prof. |
Ventilation of a building is the process of supplying outdoor air to the occupants of a building and extracting the same amount of used or contaminated air. Ventilation is also used to remove excess heat from a room.
To supply air to a room without creating draught is tricky. Sensation of draught arises when the human skin is exposed to a combination of high air velocities, cold temperatures and fluctuations. It is challenging to meet these objectives while ensuring correct and uniform air quality in all places in a room. New concepts that simplify ventilation design and increase the robustness of the system are needed.
Diffuse ventilation ceilings are a concept that uses the acoustic ceiling and the space above to distribute air to the room. The advantages are lower pressure drops by a factor of 10, non-impulse supply for a draught-free environment and the possibility of supplying air with low supply temperature because the ceiling acts as a radiant cooling panel.
This contribution is based on the work package «WP4 New ventilation solutions» sub-project of the ERACOBUILD project «School Vent Cool - Ventilation, cooling, and strategies for high performance school renovations».
We investigate a promising concept, diffuse ceiling ventilation, in real conditions in a school. Diffuse ceiling ventilation simplifies ventilation supply drastically. The concept uses the acoustic ceiling and the space above to distribute air. The advantages are lower energy consumption, draught-free supply and the possibility of supplying much cooler and fresher air to the persons in the room. At the same time acoustics are improved.
Measurements were performed in a classroom during class to test the performance. The risk of draught around the occupants has been assessed by measurements of local air velocities and temperatures. To disclose zones of stagnant or short-circuiting air, the air change effectiveness was measured with tracer gas in several locations. All measurements were performed with two air flow rates of approx. 5 and 10 l/s per person and did not show evidence of any problems. The results were very good and supported previously found results from laboratory test. Thus the concept is competitive to conventional ventilation supply.
The combination of two building elements into an integrated solution points to cheaper and faster implementation, especially in school renovation projects.
Research papers
- Integrated ventilation and night cooling in Classrooms with diffuse ceiling ventilation: Presented at Ökosan 2011, Graz, Austria. 
- Energy efficient window opening for air quality control in classrooms
- Implementation of ventilation in existing schools - a design criteria list towards passive school: Presentad at Passivehouse 2012, Brussels, Belgium. Paper + Presentation