Simulation of a passive, climate controlling façade.

A new façade concept is being developed that aims to reduce the primary energy consumption of climate installations by making use of changes in both indoor and outdoor climate. Unlike other facades, this Climate Adaptive Skin utilises mostly passive technologies to create a comfortable indoor environment all year round. To determine the potential of the new façade design, its performance is being simulated using The Mathworks program 'Simulink'. The façade utilises technologies that are already available, but not commonly used within this context. To be able to use both daytime and night time temperatures, the façade is equipped with a stack of PCM plates that is able to buffer thermal energy: in summer, cool night temperatures are used to cool the indoor environment during the day, while in winter the PCM can be heated using cheap night time electricity to heat the office during the day. To reduce the amount of energy required to heat the PCM, the façade is equipped with an air-to-air heat exchanger that uses the waste heat from exhaust air to preheat incoming ventilation air when needed. The risk of overheating in summer is reduced by using thermotropic glass that changes from transparent to translucent white above a certain threshold temperature. Once white, the glass reflects a large part of the incoming solar radiation, while still transmits diffuse light, reducing the need for artificial lighting. Simulations indicate that it is possible to keep the indoor temperature within comfortable temperature limits throughout the year using climate data from 1995 which had a very warm summer. Only during a few days in mid summer the indoor temperature becomes too high for comfort because the outdoor temperature does not get below 19°C, not even at night, preventing the PCM to shed unwanted heat during the night and preventing form cooling down. Additional research using simulations and prototypes will improve the concept design.