Guidelines for improving natural daytime ventilation in an office building with a double-skin facade

Abstract

In recent years, there has been a great deal of interest in double-skin facades due to the advantages claimed for this technology in terms of energy saving in the cold season, protection from external noise and wind loads and their high-tech image. The advent of computers and other office equipment has increased the internal heat gains in most offices. Highly glazed facades, together with the extra heat gains from the electric lighting made necessary by deep floor plans and the wider use of false ceilings, have increased the risk of overheating. To preserve comfort and reduce cooling loads, it is important to apply natural cooling strategies, including natural ventilation. Some argue that double-skin facades are designed to improve natural ventilation in buildings by the stack effect, and to allow this even in situation in which it is generally not possible due to high outdoor noise levels and/or high wind speeds. But poor operation of the double-skin facade openings can generate disastrous scenarios such as the injection of hot air from the double-skin facade into the offices and the contamination of offices on the upper floors by used air from the offices on the lower floors. This article examines how natural ventilation can be utilised in an office building with a double-skin facade during a sunny summer’s day. It mainly considers natural daytime ventilation in relation to the orientation of the double skin and the speed and direction of the wind.