A programme of testing to evaluate a passive approach to whole‐house ventilation

Abstract

PurposeThe purpose of this paper is to describe a programme of research into an innovative approach to whole‐house ventilation with heat reclaim. In order to save energy, houses are now required to be constructed to a high level of air tightness. This poses potential problems of indoor air quality, condensation and mould growth, with implications for human health. Adequate and controlled ventilation is a necessity, and in Europe the adoption of mechanical systems incorporating heat reclaim has become the preferred technology. The relatively mild climate of the UK undermines the efficiency of these fan‐driven solutions. The programme of research has been to test the viability of an engineered system of natural ventilation for use in temperate regions.Design/methodology/approachThe system works by the combination of “supply air” windows and passive stacks. The windows have an air path for incoming ventilation that passes between panes of glass, the pressure drop across the windows to induce the air flow through them is provided by the passive stacks in kitchens and bathrooms. Passive stacks are an alternative to the use of extract fans; they have been included in the building regulations since their efficacy was proven by research carried out at the Building Research Establishment in the 1980s. “Supply air” windows are manufactured in Finland, and have also been researched in Canada. The research described in this paper is the first to combine “supply air” windows and passive stacks to form a system that is completely natural and operates without the use of electricity. It has been carried out over the course of a number of projects. Beginning with laboratory studies that established the design dimensions for the windows, followed by test cell measurements, and then installation in real buildings monitored, both empty and occupied. Each stage was validated in relation to simulation models.FindingsIt was demonstrated that window U‐values of down to 0.6 W/m2/°C can be achieved. It has been demonstrated in real building applications that a reduction in overall household heating consumption of 20 per cent is attained in dwellings where the system has been installed. User approval, which was the focus of the later projects carried out in Norwich, has also been high.Originality/valueThe windows have no special installation requirements and passive stacks are a catalogue component. The windows are designed as two separate sashes that are locked together by catches that can be undone to clean the space between the panes. The system is an alternative to mechanical ventilation heat reclaim systems, it is a simple low maintenance, low‐cost method that offers good indoor air quality as well as energy advantages, which has been shown to be particularly suited to the typical winter climate conditions in the UK.