Energy simulations of a transparent-insulated office façade retrofit in London, UK

Transparent insulation materials (TIMs) have been developed for application to building facades to reduce heating energy demands of a building. The purpose of this research is to investigate the feasibility of TI-applications for high-rise and low-rise office buildings in London, UK, to reduce heating energy demands in winter and reduce overheating problems in summer. The energy performance of these office building models was simulated using an energy simulation package, Environmental Systems Performance-research (ESP-r), for a full calendar year. The simulations were initially performed for the buildings with conventional wall elements, prior to those with TI-systems (TI-walls and TI-glazing) used to replace the conventional wall elements. Surface temperatures of the conventional wall elements and TI-systems, air temperature inside the 20 mm wide air gaps in the TI-wall, dry-bulb zone temperature and energy demands required for the office zones were predicted. Peak temperatures of between 50 and 70°C were predicted for the internal surface of the TI-systems, which clearly demonstrated the large effect of absorption of solar energy flux by the brick wall mass with an absorptivity of 90 percent behind the TIM layer. In the office zones, the magnitude of temperature swings during daytime was reduced, as demonstrated by a 10 to 12 h delay in heat transmission from the external façade to the office zones. Such reduction indicates the overheating problems could be reduced potentially by TI-applications. This research presents the scale and scope of design optimisation of TI-systems with ESP-r simulations, which is a critical process prior to applications to real buildings.