In Design Builder, the thermal comfort calculation is based on ASHRAE 55-2004 [10]: air temperature 24°C, relative humidity 50%, and MRT 31°C. To achieve this
thermal comfort standard, we further estimate the chiller capacities required under the different shading options (TABLE III). The percentages here indicate the ratios of chiller required to the estimated overall energy demand of the building floors. Clearly, scheme C (i.e. fitting the external louver system on the south-facing façade) is predicted to outperform the others. However, our current simulation shows that for the ICoSS building to deliver optimal thermal comfort for present time and 2050, it requires extra energy to mitigate the excessive summer heat even if an external louver system is fitted on top of its existing natural ventilation. Therefore, the challenge for further adaptive green building technologies is how to attain the amount of chiller-running energy required while minimizing carbon emissions.