Optimization of solar heating systems for office buildings in solar enriched areas with Time-zoned heating strategy

Abstract

Time-zoned heating combined with solar heating system can improve building energy conservation, but the combined system design method is significantly different from conventional systems. Therefore, this study proposes a general overall optimization design method for solar heating system with Time-zoned heating mode from the overall consideration of system operational performance and building heating effectiveness. In addition, a Dual-objective optimization model that balances economic and heating performance has been proposed. Take an administrative office building with Time-zoned heating mode in Lhasa as an example, this study provides a suggested range of design parameters based on the analysis of the effects of different ratio of heat storage tanks volume to solar collector area (Vt/Ac). The optimization of solar collector area, heat storage tank volume, auxiliary heat source power, are achieved by employing levelized cost of heat (LCOH) and non-guaranteed heating hours as the optimization objectives. The study results indicate that the optimal Vt/Ac ratios are 0.02–0.04 m3/m2 for better system operational performance and 0.02–0.08 m3/m2 for better building heating effectiveness. Non-guaranteed heating hours occur mostly during the initial 1–2 h of heating start-up on weekdays. Meanwhile, when the non-heating guarantee hours are limited to 3500–4000 h, the solar heating system design scheme obtained from the optimized model has a certain degree of economic viability. Reducing the cost of solar collectors and heat storage tanks can help obtain more competitive solar heating system design solutions. The research results can provide new method and reference for designing solar heating system with Time-zoned heating mode.