There are already numerous small-scale solar energy collectors on the roofs of buildings in many cities in China, which are used to provide domestic hot water in most circumstances. However, these separated small-scale solar energy collectors usually do not work sufficiently as expected, particularly for fear of pipe freezing crack in severe cold winter. On the other hand, these distributed small-scale solar energy collectors would have very convenient access to local district heating system. Hence, the buildings can consume the thermal energy from local district heating system and simultaneously produce heat to local district heating system when the solar energy collectors on their roofs are available. Therefore, the buildings can become solar heat prosumers to local district heating system. In this study, a configuration on solar heat prosumers is proposed to integrate with a general district heating system. Then a thermo-hydraulic model is developed to simulate the energy performance of distributed small-scale solar heat prosumers in district heating system. The proposed model is validated in a real life case study in a north Chinses city. The simulation results showed that the solar energy penetration was about 13% of the total heat consumption in heating season of 120 days.
Building stock is a key determinant in building energy modelling and policy analysis. However, official statistics on total floor area of urban residential stock in China only exist up to 2006. Previous studies estimating Chinese urban residential stock size and energy use made various questionable methodological assumptions and only produced deterministic results. This paper presents a Bayesian approach to characterise the stock turnover dynamics and estimate stock size uncertainties. Firstly, a probabilistic dynamic model is developed to describe the building aging and demolition process governed by a hazard function specified by a parametric survival model. Secondly, with each of five candidate parametric survival models, the dynamic model is simulated through Markov Chain Monte Carlo (MCMC) to obtain posterior distributions of model-specific parameters, estimate marginal likelihood, and make predictions on stock size. Finally, Bayesian Model Averaging (BMA) is applied to create a model ensemble that combines the model-specific posterior predictive distributions of the stock evolution pathway in proportion to posterior model probabilities. This Bayesian modelling framework, and its results in the form of probability distributions of annual total stock and age-specific substocks, can provide a solid basis for further modelling and analysis of policy trade-offs across embodied-versus-operational energy consumption and carbon emissions of buildings in the context of sectorwide transition towards decarbonising buildings.
This study proposed the operation planning of the battery energy storage systems (BESS) to maximize the economic value in terms of life-cycle cost considering both the electric power self-consumption and peak load reduction. Toward this end, a bi-objective optimization model was developed in consideration of the economic net profit as well as the battery aging. An economic simulation was then conducted to create a configuration of the most cost-effective operation planning. As a result of the case study, the operation with limits on selfsufficiency rate and peak load reduction could raise the self-sufficiency rate by up to 22.1% and reduce the peak load by up to 29%, while the net present value (NPV) of the BESS was US$7,067.9 lower compared to the operation without such limits. The customers of the BESS with the PV systems can maximize their economic profits and the policy makers can establish plans for economic support schemes to improve the environmental performance of the BESS with the PV system.
Many countries have introduced various renewable energy sources to reduce carbon emissions. However, installing the renewable energy system without any energy storage system often fails to consume all of the produced energy, which then ends up being wasted. This study evaluated the economic performance of the surplus electricity trading of energy prosumer through three different business models. The proposed method can help energy prosumers to determine the business model with the highest profits and to evaluate the economic feasibility of peer-to-peer electricity trading for the future improvement.
Windows are a key design element that can affect the building energy performance and occupant psychological satisfaction. While smaller windows can increase building energy performance, they can also lower occupant psychological satisfaction. Despite the importance of determining the optimal window size by considering the building energy performance and occupant psychological satisfaction and their trade-off relationship, few studies have proposed a window size that considers both aspects. To solve this problem, this study proposed the following framework capable of accounting for both aspects in determining the optimal window size: (i) experimental settings for measuring the occupant psychological satisfaction based on the window size; (ii) virtual environment creation using SketchUp, 3dsMax, and the Unreal engine; (iii) measurement of occupant psychological satisfaction using questionnaire survey; (iv) measurement of building energy performance using SketchUp and EnergyPlus; and (v) selection of the optimal window size using the Pareto optimal solution. Using the proposed framework, even non-specialists of virtual reality or energy simulations can easily measure building energy performance and occupant psychological satisfaction by SketchUp modeling. Based on the building energy performance and occupant psychological satisfaction measured as such, the optimal window size can be determined according to building usage and conditions as well as client requirements.