For more than 100 years, temperature control has been the principal concern of our industry. That focus and our collective efforts have achieved immense improvements in the human condition – improvements so fundamental that they are usually overlooked and unappreciated, even by ourselves. We seldom reflect on what the world was like before the refrigeration of food and medicine, or before the availability of low-cost, reliable heat in the winter and cooling in the summer. However, in spite of- or because of- those achievements, the expectations of the public have moved higher.

A new model has been proposed for evaluating the discharge coefficient and flow angle at an inflow opening for cross-ventilation. This model is based on the fact that the cross-ventilation flow structure in the vicinity of an inflow opening creates dynamic similarity under the condition that the ratio of the cross-ventilation driving pressure to the dynamic pressure of cross flow at the opening is consistent. It was confirmed, from a wind tunnel experiment, that the proposed model can be applied regardless of wind direction and opening position.

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.

When do you know your ventilation ductwork needs cleaning, how do you go about it and what does hygienic mean? A new set of practical guides .. looks at addressing these issues.

More than three-fifths of the households in the U.S. heat or cool their homes with ducted forced air systems, so chances are good that air ducts are lurking within your walls, floors, or ceilings. These air ducts move conditioned air to warm and cool your family. They can be a great source of comfort-but more likely they are wasting energy and costing you money. Typical duct systems lose 25 to 40 percent of the heating or cooling energy put out by the central furnace, heat pump, or air conditioner.