A techno-economic performance study of synergies between large-scale solar district heating systems and building renovations under Tibetan Plateau climate conditions

Tibetan Plateau has a long heating period due to the high altitude and cold winters, but the high price of traditional energy sources makes it difficult to meet the heat demand. The abundant solar energy resources in the Tibetan Plateau are very conducive to the construction of solar district heating (SDH) systems, which can well solve the heating problem. Building renovations reduce the system heat load while increasing the renovation costs, which affects the economics of the system. Based on the GenOpt-TRNSYS model, the effects of building renovations and reducing end supply/return water temperatures on system performance are investigated by the hybrid optimization algorithm. The results show that under the Tibetan Plateau climate, the building renovations do not have an advantage in terms of levelized cost of heat (LCoH), but significantly reduce the total cost of the system over its entire lifecycle. The ratio of pit volume to collector area can be significantly decreased through reducing the end supply/return water temperatures based on building renovations. The unit renovation cost (URC) break-even points under the two improvement measures have been determined, with the latter being significantly higher, by approximately 60 ¥/m2. The break-even point can quantify the necessity of building renovation when constructing a large-scale solar district heating system. These provide a reference for whether to carry out building renovations while constructing solar district heating systems under the Tibetan Plateau climate.