window

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.

An important element in the natural ventilation design procedure is the flow-pressure characteristics of a window with a given opening area. The flow in the room is another important element that is often ignored in the design phase due to lack of relevant information on the air movement. This paper shows the outcome of experiments with the room air distribution. The results show that the velocity distribution in the occupied zone can be described by a semi empirical model.

In natural ventilation systems fresh air is often provided through opening of windows. However, the knowledge of the performance of windows is rather limited. Computation of natural ventilation air flow through windows is most commonly made using discharge coefficients, that are regarded as being constant. The reported results show that the discharge coefficient for a window opening cannot be regarded as a constant and that it varies considerably with the size of the opening area, the window type and the temperature difference.

The main barriers to choosing high-efficiency windows are lack of product awareness and cost considerations. As a result, residential construction professionals play a key role in promoting wise window choices to their clients.

Condensation on windows creates obscured view, can cause building damage, and may lead to mold growth and poor indoor air quality. The Canadian Standards Association (CSA) has developed new procedures to evaluate window condensation potential, using a combination of computer simulation and testing. This paper summarizes results of a study into various aspects of computer simulation related to the evaluation of condensation potential. These findings were used to assist in the development of the CSA procedures.

A currently unresolved problem in building design is the paradox between increasing demandfor good thermal insulation, and the requirement for ample levels of ventilation, to maintain ahealthy indoor environment. A possible solution to this problem is a supply air ventilatedwindow. This utilises an airflow between panes to pre-heat ventilation air to the building, andto reduce thermal convection losses thus reducing the window U-Value. At the base of thewindow is a vent to the external environment, allowing air inflow.

Within the EC-JOULE project "AIRLIT-PV", a new facade unit, integrating ventilation, daylighting, solar protection, intelligent local control and photovoltaic power, has been developed and is under evaluation by means of performance testing at four different test sites in Europe, both in test cells and in occupied buildings. This paper will summarise an extensive market survey, describe the shape and function of the unit and report on the first findings from the performance testing of the units. The ventilation performance will be emphasised.