Tweedehuidgevel als voorverwarmer van ventilatielucht. Double facade as a preheater of ventilation air.

The double facade is an extra skin around the building giving a cavity between the inner and outer facade. This cavity can be used for the control of the indoor climate. In winter solar energy absorbed by the blinds in the cavity and the heat losses through the internal facade can be used to preheat the ventilation air and can then be compared with the heat recovery unit in a mechanical ventilation system. In summer solar heat gains can be reduced by the effective sunshading system in the cavity. Then unwanted solar radiation is removed by natural ventilation in the cavity. The efficiencies of all these possibilities are studied by the section Refrigeration and Indoor Climate Technology, TU Delft. In order to make an evaluation of the overall energy efficiency buildings with double facades are simulated and analysed on a year round basis. This article is mainly focussed on the following items: how should the double facade be controlled to get the highest efficiencies; can the double facade be competitive with the heat recovery unit of a mechanical ventilation system; what is the effect of various parameters such as the dimensions of the double facade?