Effect of glazing ratio on thermal comfort and heating/cooling energy use

Glazing ratio (GR) or window-to-wall area ratio is an important factor that affects thermal loads. It also has impact on thermal environment because solar radiation through windows and warm/cold window surface temperature in different seasons. In this study, GR of 30 and 100% was compared to see their impact on thermal environment and energy use.

The study was performed based on a simple office model equipped with fan-coil system located in Paris. Air temperature-based thermostat control and operative temperature-based thermostat control were compared for both GR conditions. As expected, with 100% GR, the offices used more heating and cooling energy.

Total heating energy increased about 140–150% and cooling energy increase 55–60%. Compared to 30% GR, thermal comfort became worse. During working hours, the air temperature change became higher with 100% GR. Statistics showed that there were less occupancy hours within ±0.7 (PMV) when 100% GR was used.

Thermal conditions of north office were better than south office. The results also showed that with operative temperature control thermal comfort can be better for both north and south office. Based on the results, operative temperature control would be better to keep comfortable thermal environment for offices with high GR.