English

In the “Exemplary Buildings” program of the Brussels Capital Region, building owners and designers are challenged to realise building projects of both high architectural quality and superior environmental performance. After a project competition phase in which the Exemplary Buildings are selected, winning projects are supported by grants and expert guidance throughout further design development and construction. Building envelope airtightness is an important aspect during the follow-up, given its influence on the net energy demand.

To realize the concept of low-energy buildings, an increase in the thermal insulation performance of building parts, especially the openings that show poor insulation performance, is necessary. In addition, an adequate level of thermal comfort is also needed within residential buildings. We have developed window-applied dynamic insulation (DI), and verified thermal insulation performance in chamber and field tests.

Zero Energy Buildings require airtightness and mechanical ventilation systems to provide air changes and energy saving. These requirements contrast with the principles of natural ventilation. Through a case study located in Modena, Italy, a design strategy is proposed as a solution to integrate natural and mechanical ventilation systems at different times of the year to reduce the energy consumption in a newly designed high-density ZEB. The internal comfort evaluation for the warm season is then verified with a multizone dynamic simulation and a CFD analysis.

The article describes the results of an experimental campaign carried out at ITC-CNR in outdoor test cells to evaluate the energy performance and the related comfort level achieved through a coupled system made up of a dynamic window and a heat recovery unit.

The airtightness just after the end of a building phase is assumed to be relevant criteria for high energy performance. Testing on site the initial performance of the airtightness via the blower door test has become nowadays a common practice. This test is generally realized at the end of the construction works. What about the influence of ageing on the airtightness? Many questions exist on the durability of this initial performance.

This paper presents the new framework for the realization of reliable pressurization tests in Belgium and the provisions taken to widen the number of buildings where a valid pressurization test can be realized.

Airtightness becomes a more and more important parameter in the rationalization of the energy consumption.  The quality of the works during the construction process is essential. However, this particular step is on itself absolutely not sufficient to build airtight buildings. Airtightness has to be taken into account from the pre-project. For that, architects have to deal with a large bunch of items. Steps as the definition of the ambition level, the precise positioning of the airtightness barrier into the building are essential.

Higher insulation and air tightness levels of buildings, increase the risk on overheating. Ventilative cooling as passive technique can limit overheating and decrease cooling energy consumption. The national energy performance regulations (EPBD) determine whether, how and under which requirements ventilative cooling can assist to reduce cooling demand and overheating. Therefore, those regulations are a key factor in the market uptake of ventilative cooling. Without a realistic and achievable approach, ventilative cooling will marginally be applied in buildings.

The mixing of a tracer gas with zonal air was compared between two zones in an unoccupied test building in both the horizontal and vertical direction. A constant injection of sulphur hexafluoride (SF6) tracer gas was released into each zone separately and its concentration was measured at different positions within the zone. Variations in concentration were observed for different horizontal positions in the southern zone indicating incomplete mixing.

Passive cooling by night ventilation is one of the most promising approaches to reduce cooling energy demand of office buildings in moderate climates. However, the effectiveness of this system depends on many parameters.