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• Building-level hybrid RE systems support net-zero development goals and climate change mitigation. • Energy planning is multi-dimensional, and is affected by uncertainties. • A life cycle thinking based fuzzy decision support model is presented for identifying optimal hybrid building energy mix. • A combinatorial multi-objective optimisation was adopted considering the most viable RE technologies in the local market. • Solar PV and geothermal heating are the optimal residential energy choices for BC, under the selected case study scenario. The increasing concerns about the environmental and economic impacts of conventional centralised energy generation and fossil fuel usage have prompted an interest in renewable-based decentralised energy systems. Implementing such systems at building level can facilitate the development of net-zero energy buildings. Energy system planning is a multi-faceted problem that involves technical, economic, environmental, and social dimensions, and affects multiple stakeholders at different levels. A multi-objective optimisation approach is needed to identify the optimal energy choices at building level, while paying attention to stakeholder priorities and other constraints. The objective of this study is to develop a model to identify the optimal mix of renewable energy (RE) while also accounting for uncertainties, which can be integrated at building level with life cycle thinking. A framework was proposed for planning an optimised hybrid RE system at building level to support the net-zero development goals. The optimisation model was developed considering the objectives of minimising energy system cost, maximising operational cost savings, minimising the life cycle environmental impacts, and maximising the RE fraction. A combinatorial optimisation approach was adopted to reflect the practical engineering aspects of energy planning problems based on technologies available in the market. The developed framework was demonstrated through a case study conducted for an average multi-unit residential buildings (MURB) located in British Columbia, Canada. The results indicated that under the defined stakeholder priorities and constraints, ground source heat pumps and solar photovoltaics (PV) are the optimal energy choices for MURB, and the optimal energy system combination supplied 44% of the building's energy demand through RE. The findings will inform and guide community developers and other stakeholders with an interest in residential buildings, on the most suitable clean energy options for their building project during the pre-project planning stage. [ABSTRACT FROM AUTHOR]

• Energy upgrade is promoted by interprovincial coordinating of economy and resource. • Energy upgrade is determined by change of farmers' preference for low-quality energy. • Energy upgrade can be promoted together in agriculture and rural life. Rural energy upgrade in developing countries is an essential part of the world climate mitigation work. To systematically promote rural energy upgrade, we took the case of China and used a spatiotemporal model to investigate the spatiotemporal characteristics of energy ladders in agriculture and rural life of developing countries. The proportion of clean energy consumption in agriculture showed an interprovincial competition effect, whereas the proportion of oil consumption in rural life showed a demonstration effect. Severe reliance on coal hinders energy upgrade. Urbanisation has improved the clean level of energy use in agriculture but does not significantly affect the in rural life. Technological progress has increased the proportion of clean energy consumption but has little impact on the proportion of oil and gas consumption. The abundance of coal resources has prompted the massive use of coal and coal-fired power. Energy-use habit promotes the use of all types of energy. Except for that of gas, the consumption of different types of energy in agriculture and rural life mutually promotes. In summary, the development of energy technologies should be established based on the regional resource endowment and economic development level. Also, subsidy principles for clean energy projects should be established based on the development level of the agriculture and residents' income. Rural energy upgrade is coordinated with urbanisation and the modernisation of the agriculture and rural life styles while paying attention to the mutual promotion between the agriculture and rural life. During the change of the energy-use habit under policy guidance, attention must be paid to interprovincial cooperation. Finally, a reasonable market mechanism should be established to promote energy upgrade. [ABSTRACT FROM AUTHOR]