With recent advances in artificial intelligence (AI), built environment (BE) is getting more and more closely linked to energy. A macroscopic view of smart energy (SE) and smart built environment (SBE) is provided in this paper. Categories of smart energy systems (SESs) are divided according to the trade forms. Objectives of SBE include minimizing non-renewable energy to maintain sustainable BE, minimizing carbon exhausted to guarantee green BE, and minimizing capital cost to provide economically affordable BE. The transient fraction of power (FP) in SESs has to be controlled to obtain the optimal fraction of energy (FE). The optimal FE values depend not only on system size and time scales but also on SBE objectives. A weighted maximum volume criterion is proposed to take sustainability, green, and affordability into account. Results are compared with those optimization results based on a single objective. Methodologies for promotion of SESs from technology, system optimization, demand forecasting, and holistic design views are presented. The corresponding solution for SBE is illustrated. Challenges for future SESs for SBE are also discussed.