Optimization of the Dynamic External Shading Control for Railway Stations in China Based on Energy Use Intensity (EUI) of Lighting and HVAC Systems

Railway stations are normally designed with glazing façades and skylights to achieve aesthetic requirements and facilitate visual permeability, but this design can lead to significant energy consumption. The implementation of dynamic external shading systems together with appropriate control strategies can significantly reduce the energy consumption of HVAC systems. This study numerically investigated the lighting and cooling energy consumption of railway stations equipped with external shading systems under various climatic zones, window-to-wall ratios (WWRs), skylight-to-roof ratios (SRRs) and roller-shade performance. The study shows that lighting energy consumption varies most significantly when the shading activation threshold is set between 50 and 200 W/m2. The dynamic shading thresholds are influenced by natural lighting and solar heat gain, with the strategy changing from using natural light to reducing solar gain as the SRR increases. This study also provides the optimal activation thresholds and energy-saving rates for railway station buildings in different climatic zones using external roller shades for different external window scenarios. In Guangzhou, using roller shade A in a railway station under the maximum external window scenario achieves energy savings of 36.41%, while in Shanghai and Beijing, the energy savings are 18.12% and 23.13%, respectively. These results provide guidance for the use of dynamic external shading in railway stations in China and for the achievement of energy-reduction targets in the transport and building industries.