Double- or single-skin façades for low-carbon office refurbishments in the UK: A comparative case study

In the UK, 75 % of non-domestic buildings will still exist in 2050, andthe reduction of their emissions represents a major challenge for the UKgovernment to meet the greenhouse gases (GHG) target. There is a growingtendency towards the use of double-skin façades (DSFs) for officerefurbishments in Europe. In renovations, a DSF consists of an external glazedskin added in front of the primary building envelope and separated from it by anair cavity. DSFs have the potential to act as a thermal buffer in winter andenhance the performance of natural ventilation in summer, thus potentiallyreducing the energy consumption for heating and cooling in buildings.Limited knowledge exists about DSFs for office refurbishments and, morespecifically, the literature lacks comparisons between this technology and high-specsingle-skin refurbishments. A case study has therefore been selected to address thisgap and compare the performances of the two technologies. This chapter reportsfindings from the study of a cellular office building of the University of Brightonthat is currently undergoing a major refurbishment. The case study is analysed withthree scenarios: the building as it was, as it will be once the refurbishment is completedand as it could have been with a DSF. Detailed modelling and related energyfigures are achieved by means of building energy simulation tools and comparedagainst energy benchmarks.Results show that DSFs are a viable option for refurbishing existing officebuildings. The reduction of energy consumption with the double skin outweighsthat achieved with the single-skin refurbishment. Additionally, comfort analyses forall the scenarios considered showed that the risk of overheating with the doubleskinfaçade could be avoided by the use of shading devices to make sure that theenergy reduction is not at the expense of the building users' comfort. This studycontributes towards deepening and broadening the knowledge about performancesof DSFs within a refurbishment context and their potential advantages over highspecsingle-skin alternatives.