Transmittance optimization of tunnel shading shed for maximum energy savings and traffic safety: When replacing tunnel lighting in threshold zone

Abstract

Tunnel shading shed instead of tunnel lighting is one of the ideal ways to reduce the tremendous energy consumption at the entrance (section 2.1), but at present the length of tunnel shading shed and illuminance inside tunnel shading shed rarely meet the relevant technical requirements (section 2.2). Although some literature estimated the energy saving benefits of tunnel shading shed when replacing tunnel lighting in the threshold zone (section 2.2.1), there is no study on the conditions for maximum energy saving, the impact of energy saving on safety and the energy-saving efficiency in all time and all weather. To solve the above problems, suggest a multi-objective optimization condition of transmittance for maximizing energy savings improving traffic safety (section 3.3.2). In addition, propose an efficient sunlight simulation method based on finite element partitioning (section 3.3.1), derive a formula for precise energy-saving efficiency of tunnel shading shed (section 4.2.1), and analyze factors affecting energy-saving efficiency. The results show that: Suitable transmittance can simultaneously maximize the energy savings of tunnel shading shed (section 4.2.2) and improve traffic safety in the tunnel portal area (section 4.3). And the energy-saving efficiency on sunny summer days is not the greatest. It provides the theoretical and methodological support for making full use of sunlight and saving tunnel lighting electric energy.