Advanced Glazing Solutions for Improved Energy Consumption and Thermal Comfort in Transportation Vehicles: Numerical and Experimental Evidences

Thermal management in electric vehicles is an extremely important topic since it has a direct impact on the mile range. In winter conditions in particular, the abundant heat coming from combustion in the thermal engine is not available and the HVAC system weighs heavily on the battery balance. The challenge is to minimize the vehicle consumption while keeping at the same time an acceptable level of thermal comfort for the driver and the passengers. The glazing can be an effective leverage of improvement of the vehicle cabin thermal performances and glazing solutions exist for summer and winter conditions. The main improvements are provided by the use of double glazed units (DGUs) and thin coatings to functionalize the glass surface; those solutions exist and are available commercially. With numerical calculations we confirm the large positive impact of the DGU on the heating power consumption of a city bus in winter conditions. While a single glazing cannot equal the performances of a DGU, we show that the use of the ComfortSky® low-emissivity coating provides an appreciable improvement. We discuss a methodology to experimentally characterize thermal comfort in transport vehicles. We demonstrate its technical feasibility and its relevance on two coaches in summer conditions. Both were equipped with DGU, but, in the coach where a low-emissivity ComfortSky® coating was used, a lower operative temperature was measured, indicating a better thermal comfort. The results of thermal comfort measurements can be used to further reduce the energy consumption by refining the HVAC settings.