China's energy consumption in the building sector: A Statistical Yearbook-Energy Balance Sheet based splitting method

China's energy consumption in the building sector (BEC) is not counted as a separate type of energy consumption, but divided and mixed in other sectors in China's statistical system. This led to the lack of historical data on China's BEC. Moreover, previous researches' shortages such as unsystematic research on BEC, various estimation methods with complex calculation process, and difficulties in data acquisition resulted in “heterogeneous” of current BEC in China. Aiming to these deficiencies, this study proposes a set of China building energy consumption calculation method (CBECM) by splitting out the building related energy consumption mixed in other sectors in the composition of China Statistical Yearbook-Energy Balance Sheet. Then, China's BEC from 2000 to 2014 are estimated using CBECM and compared with other studies. Results show that, from 2000 to 2014, China's BEC increased 1.7 times, rising from 301 to 814 million tons of standard coal consumed, with the BEC percentage of total energy consumption stayed relatively stable between 17.7% and 20.3%. By comparison, we find that our results are reliable and the CBECM has the following advantages over other methods: data source is authoritative, calculation process is concise, and it is easy to obtain time series data on BEC etc. The CBECM is particularly suitable for the provincial government to calculate the local BEC, even in the circumstance with statistical yearbook available only

Feasibilities of utilizing thermal inertia of district heating networks to improve system flexibility

The use of district heating network inertia (DHNI) has been regarded as an efficient and cost-saving method to improve the flexibility of the energy systems. However, the acclaimed benefits in most studies are found in specific cases with traditional middle-temperature systems. The cases where DHNI is not feasible are unclear and the applicability of DHNI in future low-temperature district heating (LTDH) systems requires further investigations. Therefore, this study applied a top-down methodology where the practical storage potentials of DH networks are evaluated based on field investigations of 134 Swedish DH networks and 25 Chinese DH networks with various sizes and demand densities. Empirical relationships between the heat density and storage potentials are established and analyzed. Then, bottom-level analysis from technical and economical aspects are conducted on a variety of application scenarios for DHNI, including different temperature levels, heat sources, control strategies and renewable energy profiles. It is found that in LTDH system, by raising the network temperatures to actively use the DHNI, the heat source efficiency is reduced regardless the size and density of the network and, thereby, making the DHNI infeasible. This implies that the DHNI is only applicable in middle-temperature systems with combined heat and power plant (CHP) as a heat source in the extraction mode. Furthermore, the back-pressure mode is not economically attractive. In summary, the results from a multi-scenario analysis identified limited benefits of the DHNI, implying a proper consideration of its roles in future works

Integrated platform to assess seismic resilience at the community level

Due to the increasing frequency of disastrous events, the challenge of creating large-scale simulation models has become of major significance. Indeed, several simulation strategies and methodologies have been recently developed to explore the response of communities to natural disasters. Such models can support decision-makers during emergency operations allowing to create a global view of the emergency identifying consequences. An integrated platform that implements a community hybrid model with real-time simulation capabilities is presented in this paper. The platform's goal is to assess seismic resilience and vulnerability of critical infrastructures (e.g., built environment, power grid, socio-technical network) at the urban level, taking into account their interdependencies. Finally, different seismic scenarios have been applied to a large-scale virtual city model. The platform proved to be effective to analyze the emergency and could be used to implement countermeasures that improve community response and overall resilience

A multi-criteria, long-term energy planning optimisation model with integrated on-grid and off-grid electrification – The case of Uganda

While electricity access is lowest in developing countries, the academic literature on generation expansion planning (GEP) has been informed almost exclusively by challenges in industrialised countries. This paper presents the first multi-objective, long-term energy planning optimisation model tailored towards national power systems with little existing power infrastructure. It determines the location, type, capacity and timing of power system infrastructure additions. Specifically, three novel generalisations of standard generation planning are introduced: (1) an expansion of the demand constraints to allow for industrial and household electrification rates below 100%, (2) a minimisation of sub-national energy access inequality in conjunction with minimising system costs considering environmental constraints, and (3) an integration of distribution infrastructure, explicitly including both on-grid and off-grid electrification. Using a specifically designed solution algorithm based on the ε-constraint method, the model was successfully applied to the previously unexplored Ugandan national power system case. The results suggest that while it is cost-optimal to maintain highly unequal sub-national access patterns to meet Uganda's official 80% electrification target in 2040, equal access rates across all districts can be achieved by increasing discounted system cost by only 3%. High optimal shares of locationally flexible on-grid and off-grid solar energy enable cheap sub-national shifts of generation capapcity. This paper strongly challenges the Ugandan government's nuclear energy and largely grid-based electrification expansion plans. Instead, it calls for solar concentrated power as a baseload option in the future and a focus on off-grid electrification which the model selects for the majority of household connections in 2040, even in a high-demand scenario.</p

Overview of Energy Management and Leakage Control Systems for Smart Water Grids and Digital Water

Current and future smart cities are moving towards the zero-net energy use concept. To this end, the built environment should also be designed for efficient energy use and play a significant role in the production of such energy. At present, this is achieved by focusing on energy demand in buildings and to the renewable trade-off related to smart power grids. However, urban water distribution systems constantly carry an excess of hydraulic energy that can potentially be recovered to produce electricity. This paper presents a comprehensive review of current strategies for energy production by reviewing the state-of-the-art of smart water systems. New technologies (such as cyber-physical systems, digital twins, blockchain) and new methodologies (network dynamics, geometric deep learning) associated with digital water are also discussed. The paper then focuses on modelling the installation of both micro-turbines and pumps as turbines, instead of/together with pressure reduction valves, to further demonstrate the energy-recovery methods which will enable water network partitioning into district metered areas. The associated benefits on leakage control, as a source of energy, and for contributing to overall network resilience are also highlighted. The paper concludes by presenting future research directions. Notably, digital water is proposed as the main research and operational direction for current and future Water Distribution Systems (WDS) and as a holistic, data-centred framework for the operation and management of water networks.</jats:p

Definition of reference buildings to determine the effect of energy renovation measures at a neighbourhood scale: application to a study case in Braga

Dissertação de mestrado em Sustainable Built EnvironmentThe building sector is one of the major contributors to energy demand and greenhouse gases emissions within cities and, at the same time, it has one of the largest cost-effective energy saving and emissions reduction potential. In this regard, renovation projects at a neighbourhood scale instead of building level are believed to present several benefits that allow getting more profitable and efficient solutions. In this context, the dissertation work sought to develop a methodology to define reference buildings that allows evaluating energy saving measures at a neighbourhood scale for a social housing context in Portugal. The accuracy of the method was assessed by comparing the energy performance of the neighbourhood, using in one case just the reference buildings while in the other the existing buildings. For the definition of the reference buildings, a cluster analysis - which is a multivariate statistical analysis technique that groups cases with very similar characteristics into a cluster – was used. For the energy performance analysis, numerical energy simulations were used. A parametric analysis considering thirteen different energy renovation measures on the building envelope was carried out. The methodology was applied to a case study on a neighbourhood located in Braga, generally designated as “Bairro das Andorinhas”. The results showed small variation differences in the comparison analysis at a neighbourhood level for both heating and cooling energy demand, reaching maximum variations of 4.9% and 3.4% respectively. The examination of each cluster demonstrated that the heating demand had, in general, a much larger gap than the cooling demand in terms of variation between detailed calculations of the existing buildings and the reference buildings. In addition, the maximum variation for the cluster oriented East- West was found on the wall intervention measures while in the clusters oriented North- South was on the roof and windows. Finally, the use of reference buildings seems to be a viable approach to evaluate energy saving measures at a neighbourhood scale due to the level of accuracy level of the method. Moreover, the application of cluster analysis on getting reference buildings appears to be a suitable technique to define these types of buildings.O setor dos edifícios é um dos principais responsáveis pelo consumo de energia e emissão de gases com efeito estufa nas cidades e, ao mesmo tempo, possui uma das maiores poupanças rentáveis de energia e maior potencial na redução das emissões. Nesse sentido, os projetos de renovação à escala do bairro, em vez de à escala do edifício, apresentam vários benefícios que permitem obter soluções mais rentáveis e eficientes. Neste contexto, o trabalho de dissertação procurou desenvolver uma metodologia para definir edifícios de referência que permitam avaliar soluções de reabilitação energética à escala do grupo de edifícios para um bairro de habitação social em Portugal. A precisão do método foi avaliada comparando o desempenho energético do bairro, usando em um caso apenas os edifícios de referência, enquanto no outro os edifícios existentes. Para a definição dos edifícios de referência, foi utilizada uma análise de cluster - que é uma técnica de análise estatística multivariada que agrupa casos com características muito semelhantes num cluster. Para a análise do desempenho energético, foram utilizadas simulações numéricas de energia. Foi realizada uma análise paramétrica considerando treze medidas de reabilitação energética na envolvente do edifício. A metodologia foi aplicada a um caso de estudo num bairro localizado em Braga, designado como "Bairro das Andorinhas". Os resultados mostram pequenas diferenças de variação na análise comparativa à escala do bairro para as necessidades de aquecimento e arrefecimento, atingindo variações máximas de 4,9% e 3,4%, respetivamente. A análise de cada cluster demonstrou que as necessidades de aquecimento apresentaram, em geral, diferenças maiores que as necessidades de arrefecimento, em termos de variação entre os cálculos com os edifícios existentes e os edifícios de referência. Além disso, a variação máxima para o cluster orientado em direção este-oeste foi encontrada nas medidas de reabilitação da parede, enquanto nos clusters orientados em direção Norte-Sul foram encontradas no telhado e nas janelas. Finalmente, o uso de edifícios de referência parece ser uma abordagem viável para avaliar medidas de reabilitação energética à escala do bairro, devido ao nível de precisão da metodologia. Além disso, a aplicação da análise de cluster na obtenção de edifícios de referência parece ser uma técnica adequada para definir esses tipos de edifícios