Accounting for one third of global energy-related carbon emissions, the construction and operation of buildings are crucial for mitigating climate change. Decarbonization potentials of embodied and operational energy use in buildings are worth exploring from a life-cycle perspective. This paper focuses on the individual building level and collects the latest cases, to offer a comprehensive and timely understanding of the assessment and reduction of building life cycle carbon emissions (LCCEs). As for the collected cases, the operational process accounts for the largest share of building LCCEs, averaging 67%, followed by the production and construction phase, averaging 31%. Carbon emissions from the demolition process are relatively low, averaging 2%. The most commonly used method for assessing LCCEs is process-based, combining the activity level and carbon emission factors. Advanced technologies such as building information modelling and building performance simulation have been employed in recent years to assess embodied and operational carbon emissions effectively. Different approaches are proposed for the decarbonization of each stage in the building life cycle. In the production stage, the effective approaches could be optimizing the building structure, improving the material performance, and using bio-based materials, etc. Prefabrication technology is helpful to decarbonize the construction process. Energy conservation and electrification, renewable energy integration, and smart energy management can effectively reduce the building's operational carbon emissions. Beyond the life cycle, recycling waste materials is proven to have great environmental benefits. Further studies are suggested to trade off the embodied and operational carbon, to fully explore building life-cycle decarbonization potentials.

The penetration rates of intermittent renewable energies such as wind and solar energy have been increasing in power grids, often leading to a massive peak-to-valley difference in the net load demand, known as a “duck curve”. The power demand and supply should remain balanced in real-time, however, traditional power plants generally cannot output a large range of variable loads to balance the demand and supply, resulting in the overgeneration of solar and wind energy in the grid. Meanwhile, the power generation hours of the plant are forced to be curtailed, leading to a decrease in energy efficiency. Building demand response (DR) is considered as a promising technology for the collaborative control of energy supply and demand. Conventionally, building control approaches usually consider the minimization of total energy consumption as the optimization objective function; relatively few control methods have considered the balance of energy supply and demand under high renewable energy penetration. Thus, this paper proposes an innovative DR control approach that considers the energy flexibility of buildings. First, based on an energy flexibility quantification framework, the energy flexibility capacity of a typical office building is quantified; second, according to energy flexibility and a predictive net load demand curve of the grid, two DR control strategies are designed: rule-based and prediction-based DR control strategies. These two proposed control strategies are validated based on scenarios of heating, ventilation, and air conditioning (HVAC) systems with and without an energy storage tank. The results show that 24–55% of the building’s total load can be shifted from the peak load time to the valley load time, and that the duration is over 2 h, owing to the utilization of energy flexibility and the implementation of the proposed DR controls. The findings of this work are beneficial for smoothing the net load demand curve of a grid and improving the ability of a grid to adopt renewable energies.