To achieve carbon neutrality in 2060 (China), building energy-saving has been highly concerned. University buildings have great energy-saving potential as part of energy consumption where 70% of energy loss is caused by heat transfer from the envelope. However, most of the research on energy-saving factors for envelopes is limited to a certain climate or a specific building type, and the optimal configuration of envelopes under different climatic regions has not been well solved. Therefore, the influence degree and appropriate parameters of each factor of the teaching-office building envelopes on energy consumption under different climates were analyzed in this paper by orthogonal design and numerical simulation. Results show that: (1) Solar heat gain coefficient (SHGC) and indoor air change rates (ACH) [the heat transfer coefficient of the exterior wall (K_wall) and ACH] are the main factors affecting the cooling [heating] load, the insulation form of the exterior wall (W_ins) and K_wall [W_ins and solar radiation absorption coefficient of exterior surface materials (ρ_s)] have less influence; (2) The important ranking and optimal level of the influence of each factor on the cooling (or heating) loads are related to local load demands; (3) For the annual load, K_wall and the heat transfer coefficient of the exterior window (K_win) is the focus of energy-saving in severe cold and cold zones, but their impact is not significant in Guangzhou and Kunming, and the high significance of SHGC is only shown in Hohhot, Lhasa, Guangzhou, and Haikou; (4) The annual load energy savings reach 39.64%–57.57% in different climates by optimizing all factors. The research results can provide directions and data references for the energy-saving design and renovation of educational building envelopes in different climates (China).

It is very different from that of ordinary buildings due to the unique operational characteristics of university teaching-office buildings, and the energy-saving potential is huge, among them, the building’s exterior envelope is an important factor in its energy loss. It is an important basis for building energy conservation to explore the influence of the thermal parameter of the building exterior envelope on energy consumption from the perspective of thermal theory. Meanwhile, most of the buildings are old in university, limited by the actual conditions, studying the energy-saving optimization scheme from the main influencing factors and actual characteristics is a prerequisite for achieving high efficiency and energy saving. Therefore, based on the actual characteristics of university buildings, the influence law of the thermal performance of the exterior envelopes on energy demands is explored in this study through numerical simulation, and an energy-saving optimization scheme is proposed based on the existing materials. The results show that: (1) For university buildings in Chengdu, the energy-saving effect of the interior thermal insulation in exterior wall is the best; (2) the effect of insulation material type on total annual load tends to be the same as the insulation thickness is increased and stabilizes after the energy savings rate reaches 20%; (3) the selection of facing materials with low solar radiation absorption coefficients for exterior wall and roof has a much higher impact on cooling loads than on heating loads; (4) the suitable range of the heat transfer coefficient of the exterior window is 2.5 ~ 3.5, and the solar heat gain coefficient is 0.1 ~ 0.5; (5) using the optimization scheme can be saved by 18% of the heating load, 33% of the cooling load, and 28% of the total load compared to the status quo. The research results can provide a theoretical basis and data reference for energy-saving renovation of educational buildings.