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  • 1. Cao, x
    et al.
    Yuan, Y
    Xiang, B
    Sun, L
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Numerical investigation on optimal number of longitudinal fins in horizontal annular phase change unit at different wall temperatures2018In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 158, p. 384-392Article in journal (Refereed)
  • 2. Chen, X
    et al.
    Su, Y
    Aydin, D
    Bai, H
    Jarimi, H
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Raffat, S
    Experimental investigation of a polymer hollow fibre integrated liquid desiccant dehumidification system with aqueous potassium formate solution2018In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 142Article in journal (Refereed)
    Abstract [en]

    Hollow fibres have been studied as the substitute for metallic materials due to the advantages such as light weight, corrosion resistant and low cost in heat and mass transfer applications. A novel polymer hollow fibre liquid desiccant dehumidification system, in which a cross-flow hollow fibre module (fibre inside diameter=1.4mm) serves as the dehumidifier, is presented in this paper. This novel hollow fibre integrated liquid desiccant dehumidification system can be used in an air conditioning system to provide a comfortable indoor environment for hot and humid area. Compared with other conventional liquid desiccant dehumidifier, the polymer hollow fibre has a very small diameter which leads to significantly increased surface area. Moreover, the porous feature of the hollow fibre module can help to eliminate any liquid desiccant droplets carryover into the process air. As a less corrosive and more environmental friendly working fluid, aqueous potassium formate (KCOOH) solution has been selected. The dehumidification performance of the proposed system were analysed experimentally under the conditions of incoming air temperature in the range of 30°C to 45°C. The variations of dehumidification sensible and latent effectiveness, moisture removal rates were studied by varying the incoming air velocity from 0.65 m/s to 4.5m/s. With the various values of incoming air relative humidity in the range of 55% to 75% and the solution concentrations between 36% and 62%, the experimental obtained latent effectiveness are in the range of 0.25 to 0.43 and the sensible effectiveness are in the range of 0.31 to 0.52, which is in a satisfactory agreement with the empirical correlation of effectiveness-NTU in the literature.

  • 3. Chen, X.
    et al.
    Su, Y.
    Aydin, D.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Ding, Y.
    Reay, D.
    Law, R.
    Riffat, S.
    Experimental investigations of polymer hollow fibre integrated evaporative cooling system with the fibre bundles in a spindle shape2017In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 154, p. 166-174Article in journal (Refereed)
    Abstract [en]

    Due to the advantages of light weight, corrosion resistant and low cost, hollow fibres have been studied as the substitute for metallic materials. A novel hollow fibre integrated evaporative cooling system, in which the hollow fibre module constitutes as the humidifier and the evaporative cooler, is proposed. This novel hollow fibre integrated evaporative cooling system will provide a comfortable indoor environment for hot and dry area. Moreover, the water vapour can permeate through the hollow fibre effectively, and the liquid water droplets will be prevented from mixing with the processed air. In order to avoid the flow channelling or shielding of adjacent fibres, the fibres inside each bundle were made into a spindle shape to allow maximum contact between the air stream and the fibre. The cooling performances of the proposed novel polymer hollow fibre integrated evaporative cooling system were experimentally investigated under the incoming air temperature in the range of 26 °C to 32 °C and relative humidity of 25%–35%. The effects of air velocities on the cooling effectiveness, heat and mass transfer coefficients, specific water consumption and pressure drop across the polymer hollow fibre module were analysed. Two sets of experimentally derived non-dimensional heat and mass transfer correlations were summarized, which could be favourable for the future design of polymer hollow fibre integrated evaporative cooling system.

  • 4. Duan, Zhiyin
    et al.
    Zhan, Changhong
    Zhang, Xingxing
    De Montfort University.
    Mustafa, Mahmud
    Zhao, Xudong
    Alimohammadisagvand, Behrang
    Hasan, Ala
    Indirect evaporative cooling: Past, present and future potentials2012In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 16, no 9, p. 6823-6850Article in journal (Refereed)
    Abstract [en]

    This paper reported a review based study into the Indirect Evaporative Cooling (IEC) technology, which was undertaken from a variety of aspects including background, history, current status, concept, standardisation, system configuration, operational mode, research and industrialisation, market prospect and barriers, as well as the future focuses on R&D and commercialisation. This review work indicated that the IEC technology has potential to be an alternative to conventional mechanical vapour compression refrigeration systems to take up the air conditioning duty for buildings. Owing to the continuous progress in technology innovation, particularly the M-cycle development and associated heat and mass transfer and material optimisation, the IEC systems have obtained significantly enhanced cooling performance over those the decade ago, with the wet-bulb effectiveness of greater than 90% and energy efficiency ratio (EER) up to 80. Structure of the IEC heat and mass exchanger varied from flat-plate-stack, tube, heat pipe and potentially wave-form. Materials used for making the exchanger elements (plate/tube) included fibre sheet with the single side water proofing, aluminium plate/tube with single side wicked setting (grooved, meshed, toughed etc), and ceramic plate/tube with single side water proofing. Counter-current water flow relevant to the primary air is considered the favourite choice; good distribution of the water stream across the wet surface of the exchanger plate (tube) and adequate (matching up the evaporation) control of the water flow rate are critical to achieving the expected system performance. It was noticed that the IEC devices were always in combined operation with other cooling measures and the commonly available IEC related operational modes are (1) IEC/DEC system; (2) IEC/DEC/mechanical vapour compression system; (3) IEC/desiccant system; (4) IEC/chilled water system; and (5) IEC/heat pipe system. The future potential operational modes may also cover the IEC-inclusive fan coil units, air handle units, cooling towers, solar driven desiccant cycle, and Rankine cycle based power generation system etc. Future works on the IEC technology may focus on (1) heat exchanger structure and material; (2) water flowing, distribution and treatment; (3) incorporation of the IEC components into conventional air conditioning products to enable combined operation between the IEC and other cooling devices; (4) economic, environment and social impacts; (5) standardisation and legislation; (6) public awareness and other dissemination measures; and (7) manufacturing and commercialisation. All above addressed efforts may help increase the market ratio of the IEC to around 20% in the next 20 years, which will lead to significant saving of fossil fuel consumption and cut of carbon emission related to buildings.

  • 5. Freitas, Iuri
    et al.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Green building rating systems in Swedish market: A comparative analysis between LEED, BREEAM SE, GreenBuilding and Miljöbyggnad2018In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 153, p. 402-407Article in journal (Refereed)
    Abstract [en]

    In Sweden, there are four most commonly used green building rating systems, which are LEED, BREEAM SE, GreenBuilding and Miljöbyggnad. In this study, each of them is analyzed under the aspects of certification process, implementation cost, educational needs and the variety of categories. SWOT method is further applied to extract the strengths, weaknesses, opportunities and threats of each of the rating system in a direct and indirect manner, making it clearer to choose among various options when considering the individual needs of each project in practice. 

  • 6. Gu, Yaxiu
    et al.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Han, Mengjie
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Chen, Xiangjie
    Yuan, Yanping
    Techno-economic analysis of a solar photovoltaic/thermal (PV/T) concentrator for building application in Sweden using Monte Carlo method2018In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 165, p. 8-24Article in journal (Refereed)
    Abstract [en]

    The solar energy share in Sweden will grow up significantly in next a few decades. Such transition offers not only great opportunity but also uncertainties for the emerging solar photovoltaic/thermal (PV/T) technologies. This paper therefore aims to conduct a techno-economic evaluation of a reference solar PV/T concentrator in Sweden for building application. An analytical model is developed based on the combinations of Monte Carlo simulation techniques and multi energy-balance/financial equations, which takes into account of the integrated uncertainties and risks of various variables. In the model, 11 essential input variables, i.e. average daily solar irradiance, electrical/thermal efficiency, prices of electricity/heating, operation & management (OM) cost, PV/T capital cost, debt to equity ratio, interest rate, discount rate, and inflation rate, are considered, while the economic evaluation metrics, such as levelized cost of energy (LCOE), net present value (NPV), and payback period (PP), are primarily assessed. According to the analytical results, the mean values of LCOE, NPV and PP of the reference PV/T connector are observed at 1.27 SEK/kW h (0.127 €/kW h), 18,812.55 SEK (1881.255 €) and 10 years during its 25 years lifespan, given the project size at 10.37 m2 and capital cost at 4482–5378 SEK/m2 (448.2–537.8 €/m2). The positive NPV indicates that the investment on the selected PV/T concentrator will be profitable as the projected earnings exceeds the anticipated costs, depending on the NPV decision rule. The sensitivity analysis and the parametric study illustrate that the economic performance of the reference PV/T concentrator in Sweden is mostly proportional to solar irradiance, debt to equity ratio and heating price, but disproportionate to capital cost and discount rate. Together with additional market analysis of PV/T technologies in Sweden, it is expected that this paper could clarify the economic situation of PV/T technologies in Sweden and provide a useful model for their further investment decisions, in order to achieve sustainable and low-carbon economics, with an expanded quantitative discussion of the real economic or policy scenarios that may lead to those outcomes.

  • 7.
    Han, Mengjie
    et al.
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    May, Ross
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Wang, Xinru
    Pan, Song
    Yan, Da
    Jin, Yuan
    A novel reinforcement learning method for improving occupant comfort via window opening and closingManuscript (preprint) (Other academic)
  • 8.
    Han, Mengjie
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics.
    May, Ross
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Wang, Xinru
    Pan, Song
    Yan, Da
    Jin, Yuan
    Xu, Liguo
    A review of reinforcement learning methodologies for controlling occupant comfort in buildings2019In: Sustainable cities and society, ISSN 2210-6707, Vol. 51, article id 101748Article in journal (Refereed)
  • 9.
    Han, Mengjie
    et al.
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Xu, Liguo
    May, Ross
    Pan, Song
    Wu, Jinshun
    A review of reinforcement learning methodologies on control systems for building energy2018Report (Other academic)
    Abstract [en]

    The usage of energy directly leads to a great amount of consumption of the non-renewable fossil resources. Exploiting fossil resources energy can influence both climate and health via ineluctable emissions. Raising awareness, choosing alternative energy and developing energy efficient equipment contributes to reducing the demand for fossil resources energy, but the implementation of them usually takes a long time. Since building energy amounts to around one-third of global energy consumption, and systems in buildings, e.g. HVAC, can be intervened by individual building management, advanced and reliable control techniques for buildings are expected to have a substantial contribution to reducing global energy consumptions. Among those control techniques, the model-free, data-driven reinforcement learning method seems distinctive and applicable. The success of the reinforcement learning method in many artificial intelligence applications has brought us an explicit indication of implementing the method on building energy control. Fruitful algorithms complement each other and guarantee the quality of the optimisation. As a central brain of smart building automation systems, the control technique directly affects the performance of buildings. However, the examination of previous works based on reinforcement learning methodologies are not available and, moreover, how the algorithms can be developed is still vague. Therefore, this paper briefly analyses the empirical applications from the methodology point of view and proposes the future research direction.

  • 10. He, W.
    et al.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Solar Heating, Cooling and Power Generation — Current Profiles and Future Potentials2019In: Advanced Energy Efficiency Technologies for Solar Heating, Cooling and Power Generation / [ed] Xudong ZhaoXiaoli Ma, Springer, 2019, p. 31-78Chapter in book (Refereed)
    Abstract [en]

    Due to the large amount of consumption of the fossil fuels, the ecological environment has suffered serious pollution and damage. Solar power technologies provide the best solution to the current energy and environment issues. In past decades, global solar thermal capacity increased rapidly, and now it has been used worldwide to provide heating, cooling and power generation. However, after years of development, solar energy utilization technology still faces problems such as low efficiency, high cost, difficulty in energy storage and unstable energy supply, which have been seriously restricting its applications. This chapter briefly summarizes the concept and classification of solar heating, cooling and power generation. Furthermore, some technology development and potential applications relating to solar heating, cooling and power generation are discussed.

  • 11. He, Wei
    et al.
    Hong, Xiaoqiang
    Zhao, Xudong
    Zhang, Xingxing
    University of Hull.
    Shen, Jinchun
    Ji, Jie
    Operational performance of a novel heat pump assisted solar facade loop-heat-pipe water heating system2015In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 146, p. 371-382Article in journal (Refereed)
    Abstract [en]

    This paper aims to present an investigation into the operational performance of a novel heat pump assisted solar façade loop-heat-pipe (LHP) water heating system using both theoretical and experimental methods. This involved (1) development of a computer numerical model; (2) simulation of the operational performance of the system by using the model; (3) test rig construction; and (4) dedicated experiment for verification of the model. It was found that the established model is able to predict the operational performance of the system at a reasonable accuracy. Analyses of the research results indicated that under the selected testing conditions, the average thermal efficiency of the LHP module was around 71%, much higher than that of the loop heat pipe without heat pump assistance. The thermal efficiency of the LHP module grew when the heat pump was turned-on and fell when the heat pump was turned-off. The water temperature remained a steadily growing trend throughout the heat pump turned-on period. Neglecting the heat loss of the water tank, the highest coefficient of the performance could reach up to 6.14 and its average value was around 4.93. In overall, the system is a new façade integrated, highly efficient and aesthetically appealing solar water heating configuration; wide deployment of the system will help reduce fossil fuel consumption in the building sector and carbon emission to the environment.

  • 12. He, Wei
    et al.
    Hong, Xiaoqiang
    Zhao, Xudong
    Zhang, Xingxing
    University of Hull.
    Shen, Jinchun
    Ji, Jie
    Theoretical investigation of the thermal performance of a novel solar loop-heat-pipe facade-based heat pump water heating system2014In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 77, p. 180-191Article in journal (Refereed)
    Abstract [en]

    The aim of the paper was to present a dedicated theoretical investigation into the thermal performance of a novel solar loop-heat-pipe façade based heat pump water heating system. This involved thermo-fluid analyses, computer numerical model development, the model running up, modelling result analyses and conclusion. An energy balance network was established on each part and the whole range of the system to address the associated energy conversion and transfer processes. On basis of this, a computer numerical model was developed and run up to predict the thermal performance of such a system at different system configurations, layouts and operational conditions. It was suggested that the loop heat pipes could be filled with either water, R134a, R22 or R600a; of which R600a is the favourite working fluid owing to its relatively larger heat transfer capacity and positive pressure in operation. Variations in the system configuration, i.e., glazing covers, heat exchangers, would lead to identifiable differences in the thermal performance of the system, represented by the thermal efficiency and COP. Furthermore, impact of the external operational parameters, i.e., solar radiation and ambient air temperature, to the system's thermal performance was also investigated. The research was based on an innovative loop-heat-pipe façade and came up with useful results reflecting the thermal performance of the combined system between the façade and heat pump. This would help promote development and market penetration of such an innovative solar heating technology, and thus contribute to achieving the global targets in energy saving and carbon emission reduction.

  • 13. He, Wei
    et al.
    Zhang, Gan
    Zhang, Xingxing
    University of Nottingham.
    Ji, Jie
    Li, Guiqiang
    Zhao, Xudong
    Recent development and application of thermoelectric generator and cooler2015In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 143, p. 1-25Article in journal (Refereed)
    Abstract [en]

    Energy crisis and environment deterioration are two major problems for 21st century. Thermoelectric device is a promising solution for those two problems. This review begins with the basic concepts of the thermoelectric and discusses its recent material researches about the figure of merit. It also reports the recent applications of the thermoelectric generator, including the structure optimization which significantly affects the thermoelectric generator, the low temperature recovery, the heat resource and its application area. Then it reports the recent application of the thermoelectric cooler including the thermoelectric model and its application area. It ends with the discussion of the further research direction.

  • 14. Hu, J
    et al.
    Chen, W
    Yin, Y
    Li, Y
    Yang, D
    Wang, H
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Electrical-thermal-mechanical properties of multifunctional OPV-ETFE foils for transparent membrane buildings2018In: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 66, p. 394-402Article in journal (Refereed)
    Abstract [en]

    ETFE (ethylene tetrafluoroethylene) foils integrated organic photovoltaic cells (OPV) have attracted considerable attention in recent years due to the achievement of sustainability. As building materials, multifunctional OPV-ETFE foils could produce electricity, store thermal energy and possess structural capability. In this case, electrical, thermal and mechanical properties coexist and influence each other due to photovoltaic/thermal effects. Understanding the fundamental mechanism is significant to analyze and design corresponding structures. This paper concerns coupled properties of OPV-ETFE specimens with controlled experiments. One-parameter and two-parameter analysis of two typical specimens are performed to investigate essential properties. Experimental observations show that within normal working conditions, electrical properties are relatively independent but that thermal-mechanical properties are related to each other. Yield stress, yield strain and elastic modulus are calculated from stress-strain curves; these mechanical properties are comparable with those of original ETFE foils at the same temperature. It is concluded from temperature-stress curves that yield point has a critical effect on temperature-stress correlation and that mechanical properties of double OPV specimens are better than those of single OPV specimens. Generally, these mechanical properties could provide basic insights into evaluation of energetic performance and structural behavior of transparent membrane buildings.

  • 15. Huang, P
    et al.
    Fan, C
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Wang, J
    A hierarchical coordinated demand response control for buildings with improved performances at building group2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 242, p. 684-694Article in journal (Refereed)
    Abstract [en]

    Demand response control is one of the common means used for building peak demand limiting. Most of the existing demand response controls focused on single building’s performance optimization, and thus may cause new undesirable peak demands at building group, imposing stress on the grid power balance and limiting the economic savings. A few latest studies have demonstrated the potential benefits of demand response coordination, but the proposed methods cannot be applied in large scales. The main reason is that, for demand response coordination of multiple buildings, associated computational load and coordination complexity, increasing exponentially with building number, are challenges to be solved. This study, therefore, proposes a hierarchical demand response control to optimize operations of a large scale of buildings for group-level peak demand reduction. The hierarchical control first considers the building group as a ‘virtual’ building and searches the optimal performance that can be achieved at building group using genetic algorithm. To realize such optimal performance, it then coordinates each single building’s operation using non-linear programming. For validations, the proposed method has been applied on a case building group, and the study results show that the hierarchical control can overcome the challenges of excessive computational load and complexity. Moreover, in comparison with conventional independent control, it can achieve better performances in aspects of peak demand reduction and economic savings. This study provides a coordinated control for application in large scales, which can improve the effectiveness and efficiency in relieving the grid stress, and reduce the end-users’ electricity bills.

  • 16.
    Huang, Pei
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology. City University of Hong Kong.
    Fan, Cheng
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Wang, Jiayuan
    A hierarchical coordinated demand response control for buildings with improved performances at building group2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 242, p. 684-694Article in journal (Refereed)
    Abstract [en]

    Demand response control is one of the common means used for building peak demand limiting. Most of the existing demand response controls focused on single building’s performance optimization, and thus may cause new undesirable peak demands at building group, imposing stress on the grid power balance and limiting the economic savings. A few latest studies have demonstrated the potential benefits of demand response coordination, but the proposed methods cannot be applied in large scales. The main reason is that, for demand response coordination of multiple buildings, associated computational load and coordination complexity, increasing exponentially with building number, are challenges to be solved. This study, therefore, proposes a hierarchical demand response control to optimize operations of a large scale of buildings for group-level peak demand reduction. The hierarchical control first considers the building group as a ‘virtual’ building and searches the optimal performance that can be achieved at building group using genetic algorithm. To realize such optimal performance, it then coordinates each single building’s operation using non-linear programming. For validations, the proposed method has been applied on a case building group, and the study results show that the hierarchical control can overcome the challenges of excessive computational load and complexity. Moreover, in comparison with conventional independent control, it can achieve better performances in aspects of peak demand reduction and economic savings. This study provides a coordinated control for application in large scales, which can improve the effectiveness and efficiency in relieving the grid stress, and reduce the end-users’ electricity bills.

  • 17.
    Huang, Pei
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Lovati, Marco
    EURAC Research, Bolzano, Italy; University of Trento, Trento, Italy.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Hallbeck, Sven
    NIBE Climate Solutions, Sweden.
    Becker, Anders
    Ferroamp Elektronik AB, Spånga, Sweden.
    Bergqvist, Henrik
    LudvikaHem AB Bobutiken, Ludvika, Sweden.
    Hedberg, Jan
    LudvikaHem AB Bobutiken, Ludvika, Sweden.
    Maturi, Laura
    EURAC Research, Bolzano, Italy.
    Transforming a residential building cluster into electricity prosumers in Sweden: Optimal design of a coupled PV-heat pump-thermal storage-electric vehicle system2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 255, article id 113864Article in journal (Refereed)
    Abstract [en]

    Smart grid is triggering the transformation of traditional electricity consumers into electricity prosumers. This paper reports a case study of transforming an existing residential cluster in Sweden into electricity prosumers. The main energy concepts include (1) click-and-go photovoltaics (PV) panels for building integration, (2) centralized exhaust air heat pump, (3) thermal energy storage for storing excess PV electricity by using heat pump, and (4) PV electricity sharing within the building cluster for thermal/electrical demand (including electric vehicles load) on a direct-current micro grid. For the coupled PV-heat pump-thermal storage-electric vehicle system, a fitness function based on genetic algorithm is established to optimize the capacity and positions of PV modules at cluster level, with the purpose of maximizing the self-consumed electricity under a non-negative net present value during the economic lifetime. Different techno-economic key performance indicators, including the optimal PV capacity, self-sufficiency, self-consumption and levelized cost of electricity, are analysed under impacts of thermal storage integration, electric vehicle penetration and electricity sharing possibility. Results indicate that the coupled system can effectively improve the district-level PV electricity self-consumption rate to about 77% in the baseline case. The research results reveal how electric vehicle penetrations, thermal storage, and energy sharing affect PV system sizing/positions and the performance indicators, and thus help promote the PV deployment. This study also demonstrates the feasibility for transferring the existing Swedish building clusters into smart electricity prosumers with higher self-consumption and energy efficiency and more intelligence, which benefits achieving the ‘32% share of renewable energy source’ target in EU by 2030.

  • 18. Lei, S.
    et al.
    Shi, Y.
    Yan, Y.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Numerical study on inertial effects on liquid-vapor flow using lattice Boltzmann method2019In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 160, p. 428-435Article in journal (Refereed)
    Abstract [en]

    Liquid-vapor flow in porous media is studied in this article. To fulfill this goal, a double-distribution-function lattice Boltzmann (LB) model is proposed based on the separate-phase governing equations at the representative elementary volume (REV) scale. Importantly, besides the Darcy force and capillary force, which were commonly included in previous studies, the LB model in this article also considers the inertial force characterized by the Forchheimer term. This feature enables the model to offer an effective description of liquid-vapor flow in porous media at low, intermediate and even high flow rates. We validated the LB model by simulating a single-phase flow in porous media driven by a pressure difference and found its results are in good agreement with the available analytical solutions. We then applied the model to study water-vapor flow in a semi-infinite porous region bounded by an impermeable and heated wall. The numerical simulation reveals the flow and mass transfer characteristics under the compounding effects of inertial, Darcy and capillary forces. Through a comparison with the results given by the generalized Darcy's law, our numerical results directly evidence that the inertial force is a dominating factor when a fluid passes through porous media at an intermediate or high flow rate.

  • 19. Li, G.
    et al.
    Tang, L.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Dong, J.
    Xiao, M.
    Factors affecting greenhouse microclimate and its regulating techniques: a review2018In: IOP Conference Series: Earth and Environmental Science, 2018, Vol. 167, no 1, article id 012019Conference paper (Refereed)
    Abstract [en]

    This paper reviews factors affecting greenhouse microclimate and its regulating techniques towards upgrading the greenhouse applications in the area of southeast China which have little or very basic technology integration. The microclimate of greenhouse is apparently influenced by the shape and its orientation, the wind direction, the property of covering material, and the use of insect-proof screen as they eventually affect the total solar radiation, the thermal characterises, and the flow pattern inside. The natural ventilation and sun block are the most common method to cool the greenhouse, but more efficient evaporative cooling such as pad-fan system, misting/fogging system and roof sprinkler are required with extreme temperatures. The earth to air heat exchanger and the heat storage using phase change material may be used for heating or cooling throughout the year which are more economic and energy-saving than other traditional thermal technologies. The reviewed knowledge provides insights into upgrading greenhouse applications in Ningbo area towards more sustainable and efficient greenhouse farming.

  • 20. Li, G
    et al.
    Tang, L
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Hao, J
    Xiao, M
    Dong, J
    Numerical and experimental investigations on improving the efficiency of Clean-In-Place procedures in closed processing systems: A review2017Conference paper (Refereed)
    Abstract [en]

    This paper reviews the recent numerical and experimental investigations on improving the efficiency of Clean-In-Place procedures thus saving operation energy. The paper covers the fouling of equipment surfaces, the concept of CIP and its operation practices, the physical factors controlling the efficiency of CIP procedures with a special attention being paid to the hydrodynamic force of the cleaning fluids. The studies show that CIP efficiency dependents on many factors, such as the type of soil to be removed, the cleaning time, the temperature of cleaning agent, and the favourable hydrodynamic force of the moving liquid. Among the hydrodynamic factors, the wall shear stress and its fluctuation rate reported to be the dominating factor for cleaning straight circular pipes. Whilst for cleaning of more complex geometries and areas difficult to clean, the controlling factor may also include the flow pattern, flow exchange, flow turbulence, and the property of the recirculation zone.

  • 21. Li, Guozhen
    et al.
    Tang, Llewellyn
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Dong, Jie
    A review of factors affecting the efficiency of clean-in-place procedures in closed processing systems2019In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 178, p. 57-71Article in journal (Refereed)
    Abstract [en]

    This paper reviews the current state of researches on improvement of Clean-In-Place (CIP) procedures in closed processing system thus saving energy, with a special attention paid to the hydrodynamic effects of cleaning fluid and the numerical and experimental approaches to investigate the identified controlling factors. The paper discussed the fouling problems of processing plants and the importance of sufficient CIP procedures, the forces contributing to cleaning with a special focus on the hydrodynamic effects. In general, it is possible to enhance hydrodynamic removal forces by local introduction of, among others, high wall shear stress and fluctuation rate of wall shear stress without consuming more energy. A theoretical model of particle removal in flow was also reviewed which supports the factors identified. The paper therefore further reviewed and compared the current state of modelling and experimental techniques on CIP improvement. To simulation the CIP process, it is necessary to consider 3D time-resolved Large Eddy Simulation with a Hybrid RANS-LES WMLES as Sub-Grid-Scale model because it captures both the mean and fluctuation rate of flow variables, while affordable for industrial flows. The wall shear stress measurement techniques and cleanablity test methods were also discussed and suggested.

  • 22. Li, Guozhen
    et al.
    Tang, Llewellyn
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Xiao, Manxuan
    Dong, Jie
    Effect of solar radiation and natural ventilation on temperature distribution in a greenhouse: a numerical study2017Conference paper (Refereed)
  • 23. Liu, G
    et al.
    Xiao, M
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Gál, Csilla V
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Chen, X
    Liu, L
    Pan, S
    Wu, J
    Tang, L
    Clements-Croome, D
    A review of air filtration technologies for sustainable and healthy building ventilation2017In: Sustainable cities and society, ISSN 2210-6707, Vol. 32, p. 375-396Article in journal (Refereed)
    Abstract [en]

    Urbanization increased population density in cities and consequently leads to severe indoor air pollution. As a result of these trends, the issue of sustainable and healthy indoor environment has received increasing attention. Various air filtration techniques have been adopted to optimize indoor air quality. Air filtration technique can remove air pollutants and effectively alleviate the deterioration of indoor air quality. This paper presents a comprehensive review on the synergistic effect of different air purification technologies, air filtration theory, materials and standards. It evaluated different air filtration technologies by considering factors such as air quality improvement, filtering performance, energy and economic behaviour, thermal comfort and acoustic impact. Current research development of air filtration technologies along with their advantages, limitations and challenges are discussed. This paper aims to drive the future of air filtration technology research and development in achieving sustainable and healthy building ventilation.

  • 24. Liu, Haoyang
    et al.
    Zhang, Xingxing
    Saffa, Riffat
    A Novel Vacuum Window System2011In: Proceeding 10th International Conference on Sustainable Energy Technologies, Istanbul, Turkey, 04th -07th September 2011, 2011Conference paper (Refereed)
  • 25. Liu, Shengchun
    et al.
    Hao, Ling
    Rao, Zhiming
    Zhang, Xingxing
    University of Nottingham.
    Experimental study on crystallization process and prediction for the latent heat of ice slurry generation based sodium chloride solution2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 185, p. 1948-1953Article in journal (Refereed)
    Abstract [en]

    The research on the crystallization process is a fundamental task for the investigation of freezing properties of ice slurry. This paper presents an experimental study on the influence of concentration on essential parameters of the crystallization process for the ice slurry produced from sodium chloride solution using a scraped surface heat exchanger. It was found that the liquid temperature experiences four different segments during the whole crystallization process. This trend keeps accordance with the result from literature and it was used to verify the accuracy of the experiment test. It was also observed that the concentrations of sodium chloride solution have significant effects on several freezing properties of the ice slurry generation. The curves obtained in this paper are useful to predict the freezing point and the solidification time in practice. Additionally, a mathematical correlation between the latent heat and concentration was developed eventually by polynomial fitting the curve gained from experiments. The error between the fitting curves and original experimental data was no more than 5%. Totally, during the ice generation process, it is of great significance that the concentration of brine solution can be adjusted to meet the cooling capacity requirement according to the fitting curves and mathematical correlations obtained in this paper.

  • 26. Liu, Xuezhi
    et al.
    Liu, Huolong
    Zhang, Xingxing
    University of Hull.
    Zhao, Xudong
    Transmission network expansion planning by improved simulated annealing approach2014In: SOP Transactions on Power Transmission and Smart Grid, ISSN 2380-0003, Vol. 1, no 1, p. 1-8Article in journal (Refereed)
    Abstract [en]

    The transmission network expansion planning problem is effectively solved by the improved simulated annealing approach. A mixed integer nonlinear programming model of this problem is formulated using the DC power flow model. The detailed process of simulated annealing algorithm has been improved, and applied to 6-bus and 24-bus systems. The solutions obtained by the improved SA approach are compared with solutions found using LINGO software. Numerical results have shown that the proposed approach requires less time to obtain local optimal solutions.

  • 27. Liu, Xuezhi
    et al.
    Zhang, Xingxing
    University of Hull.
    Zhao, Xudong
    Liu, Huolong
    Damping control for power system based on state observer2014In: SOP Transactions on Power Transmission and Smart Grid, ISSN 2380-0003, Vol. 1, no 1, p. 9-19Article in journal (Refereed)
    Abstract [en]

    In this work, design of damping controller for Power System based on state observer is studied. The linearized state equation model of multi-machine power system is built, which includes four-order generator model and three-order excitation model. The power system damping characteristic is improved using feedback control based on the states that are estimated by full-order and reduced-order observer. The simulation results using a four-machine two-area system is utilized to validate the effectiveness of the proposed method.

  • 28. Lu, Lu
    et al.
    Yan, Yuting
    Zhang, Xingxing
    Li, Junming
    Zhao, Xudong
    Theoretical Study on City Gas Pipeline Leakage and Diffusion2013In: Proceeding 13th International Conference on Sustainable Energy Technologies, Hong Kong, 28th -30th August 2013, 2013Conference paper (Refereed)
  • 29. Lu, Lu
    et al.
    Zhang, Xingxing
    University of Hull.
    Yan, Yuting
    Li, Jun-Ming
    Zhao, Xudong
    Theoretical analysis of natural-gas leakage in urban medium-pressure pipelines2014In: Journal of Environment and Human, ISSN 2373-8324, Vol. 1, no 2, p. 71-86Article in journal (Refereed)
    Abstract [en]

    With widespread deployment of the urban natural gas industry, the energy security is now becoming one of the priorities in practice. Gas leakage may occur from the pipeline during the collection and transportation process. This article therefore presented a theoretical study on the urban natural gas pipeline leakage in order to provide the basic theory of the rescue policy making in emergent occasions. The investigation was undertaken through the fundamental analysis based on derivation of gas leakage models. The gas leakage model was applied to analyze the pressure, temperature and flow rate of gas leakage over time under both the steady-state and dynamic conditions. Two main impacting factors, pressure and hole size, were subsequently discussed. It is concluded that for the steady leakage the flow rate increases with the increase of pipeline pressure and hole size. And the distribution of pressure, temperature, density and velocity were calculated along the pipeline. For the unsteady leakage, the time of leakage is very short under different initial pressure and hole size, and the total leakage and average leakage rates were analyzed.

  • 30. Lu, Lu
    et al.
    Zhang, Xingxing
    Zhao, Xudong
    Numerical simulation of gas pipeline leakage and diffusion2014Conference paper (Refereed)
  • 31. Luo, H.
    et al.
    Liang, X.
    Lu, J.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Applicability analysis of insulation in different climate zones of China2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 142, p. 1835-1841Article in journal (Refereed)
    Abstract [en]

    In this paper we evaluated the applicability of the widely-used passive design strategy i.e., insulation, in three typical climate zones of China. Software IES VE was used for modelling and simulation of performance of insulation in a residential house. The practical behavior patterns of Chinese family from survey were utilized for analyzing the thermal characteristics of the house. Four parameters of the results were selected for analyzing the performance of insulation in three cities of China. The conditions varying in time periods and locations were compared on the basis of the simulation.

  • 32. Ma, Tianqi
    et al.
    Jia, Zhenyuan
    Li, Hongqi
    Zhang, Xingxing
    Zhao, Xudong
    Optimization of Integrated Energy Process in China Industrial Compressed Air System2013Conference paper (Refereed)
  • 33.
    Myhren, Jonn Are
    et al.
    Dalarna University, School of Technology and Business Studies, Construction.
    Heier, Johan
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Hugosson, Mårten
    Dalarna University, School of Technology and Business Studies, Business Administration and Management.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    The perception of Swedish housing owner’s on the strategies to increase the rate of energy efficient refurbishment of multi-family buildings2018In: Intelligent Buildings International, ISSN 1750-8975, E-ISSN 1756-6932Article in journal (Refereed)
    Abstract [en]

    Improving the energy performance of existing buildings is crucial for reaching both EU and national climate and energy targets. The main objective of this study was to map challenges that Swedish housing owners perceive when making energy-efficiency refurbishments. A secondary objective was to compare how well these challenges relate to national strategies. The study applied a combined methods approach with audience response meters and in-depth qualitative semi-structured interviews. The housing owners express the view that they have sufficient knowledge of national ambitions to improve the energy performance of buildings and welcome the new building regulations. Despite this supposed knowledge and the current economic situation with beneficial loans, the refurbishment rate still remains low. The housing owners explain that they are concerned about the ‘performance gap’ and request more accurate energy performance predictions. They are also waiting for proof that all sustainability goals can be reached in reality. Probably, too few projects fulfilling ambitions in all categories: economically, socially and energy-wise have been followed up and demonstrated nationally. The new national information centre on refurbishment of buildings may help to spread information about such projects, raise awareness and thus increase the refurbishment rate.

  • 34. Pan, S.
    et al.
    Wang, H.
    Pei, F.
    Yang, L.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    An investigation on energy consumption of air conditioning system in Beijing subway stations2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 142, p. 2568-2573Article in journal (Refereed)
    Abstract [en]

    This paper initially depicted on the energy consumption of air conditioning systems in Beijing subway stations. An investigation was conducted among ten underground subway stations to the examination of practical operation conditions of their cooling units. The overall field testing included information such as air conditioning system formation, equipment types, system operation parameters, energy consumption and system operation efficiency. The results showed that the COP value of refrigerators in the tested subway stations were generally high at about 4.4 in average. Nevertheless, the mean EER and SCOP values were nearly 27% and 48% lower than the average COP value due to the large amount of energy consumption in water pumps, cooling towers and fans. There was a big difference among each station in terms of the instantaneous power consumption of air conditioning systems. The most energy consuming station was nearly seven times higher than the least one. It was observed that there was a lack of maintenance and system operation strategy for these underground air condition systems. A promising potential for energy saving was found out within the air conditioning systems in Beijing subway stations.

  • 35. Pan, S
    et al.
    Xiong, Y
    Han, Y
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Xia, L
    Wei, S
    Wu, J
    Han, Mengjie
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    A study on influential factors of occupant window-opening behavior in an office building in China2018In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 133, p. 41-50Article in journal (Refereed)
    Abstract [en]

    Occupants often perform many types of behavior in buildings to adjust the indoor thermal environment. In these types, opening/closing the windows, often regarded as window-opening behavior, is more commonly observed because of its convenience. It not only improves indoor air quality to satisfy occupants' requirement for indoor thermal comfort but also influences building energy consumption. To learn more about potential factors having effects on occupants' window-opening behavior, a field study was carried out in an office building within a university in Beijing. Window state (open/closed) for a total of 5 windows in 5 offices on the second floor in 285 days (9.5 months) were recorded daily. Potential factors, categorized as environmental and non-environmental ones, were subsequently identified with their impact on window-opening behavior through logistic regression and Pearson correlation approaches. The analytical results show that occupants' window-opening behavior is more strongly correlated to environmental factors, such as indoor and outdoor air temperatures, wind speed, relative humidity, outdoor FM2.5 concentrations, solar radiation, sunshine hours, in which air temperatures dominate the influence. While the non-environmental factors, i.e. seasonal change, time of day and personal preference, also affects the patterns of window-opening probability. This paper provides solid field data on occupant window opening behavior in China, with high resolutions and demonstrates the way in analyzing and predicting the probability of window-opening behavior. Its discussion into the potential impact factors shall be useful for further investigation of the relationship between building energy consumption and window-opening behavior.

  • 36. Pan, Song
    et al.
    Du, Saisai
    Wang, Xinru
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Xia, Liang
    Liu, Jiaping
    Pei, Fei
    Wei, Yixuan
    Analysis and interpretation of the particulate matter (PM10 and PM2.5) concentrations at the subway stations in Beijing, China2019In: Sustainable cities and society, ISSN 2210-6707, Vol. 45, p. 366-377Article in journal (Refereed)
    Abstract [en]

    The particulate matters (PM10 and PM2.5) inside urban subway stations greatly influence indoor air quality and passenger comfort. This study aims to analyze and interpret the concentrations of PM10 and PM2.5, measured in several subway stations from October 9th to 22nd, 2016 in Beijing, China. The overall methodology was based on the Statistical Package for Social Science (SPSS) software while General linear model (GLM) and correlation analysis were further applied to examine the sensitivities of different variables to the particle concentrations. The data analysis showed the average overall mass ratio of PM concentrations inside subway station is about 68.7%, much lower than outdoor condition (79.6%). In the areas of the station hall and platform, the real-time PM10 and PM2.5 concentrations varied periodically. In working and operation offices, all rooms had much higher PM concentrations than the outdoor environment when its pollution level was level 3, in which the facility room reached the highest level, while the closed meeting room had the lowest. Correlation analysis results indicated that PM10 and PM2.5 concentrations were mutually correlated (average R2 = 0.854), and a strong linear correlation (R2 = 0.897) of the subway-station PM concentrations to the outdoor PM conditions, regardless of the outdoor atmospheric PM concentrations pollution level was. Nevertheless, the impact of passenger number and temperature & humidity on the station PM concentrations was less, when compared to the outdoor environment. This paper is expected to provide useful information for further research and design of effective prevention measures on PM in local subway stations, towards a more sustainable and healthier built environment in the city underground. 

  • 37. Pan, Song
    et al.
    Pei, Fei
    Wang, Hongwei
    Liu, Jiaping
    Wei, Yixuan
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Li, Guoqing
    Gu, Yaxiu
    Design and experimental study of a novel air conditioning system using evaporative condenser at a subway station in Beijing, China2018In: Sustainable cities and society, ISSN 2210-6707, Vol. 43, p. 550-562Article in journal (Refereed)
    Abstract [en]

    Air conditioning system (AC) contributes significantly to the energy consumption of underground metros. In China, most metro stations are designed with water-cooling centralized air conditioning (WC-AC) system, it has been found that several serious problems are brought by this conventional system, such as large space occupying, water leaking, cooling tower noise and low system efficiency. In order to solve these problems, a novel energy-efficient AC system incorporating an independent evaporative condenser (EC) has been proposed and installed at Futong metro station in Beijing, China. A series of pilot measurements were conducted to analyze the cooling performance and energy consumption of this novel EC-AC system. During the testing period, the average refrigeration efficiency of COP, SCOP and ACOP in A and B side is up to 3.8/3.9, 3.4/3.4 and 2.5/2.3. At the same time, some operation problems such as unbalanced working condition have been identified during measurement. The research indicates that such EC-AC system could be a feasible solution to enhance the energy efficiency and reduce the operational costs and carbon emission in metro stations.

  • 38. Pan, Song
    et al.
    Wang, Xingru
    Wei, Shen
    Xu, Chuanqi
    Zhang, Xingxing
    University of Nottingham.
    Xie, Jingchao
    Tindall, Jess
    de Wilde, Pieter
    Energy waste in buildings due to occupant behaviour2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 105, p. 2233-2238Article in journal (Refereed)
    Abstract [en]

    Occupants’ behaviour has a significant impact on the energy performance of buildings. A good understanding of how occupants use a building provides a possibility of promoting the building's energy efficiency through changing occupant behaviour. Building simulation has been adopted as a useful method by building engineers for quantifying the effects of changing occupant behaviour on the building's energy consumption and indoor environment. However, due to the lack of real measured data with respect to how occupants use the building, such simulation work has relied on assumed behavioural patterns, which significantly reduces the reliability of the predicted results. This paper describes a longitudinal study monitoring occupants’ heating, window opening and cooling behaviour in an office building throughout summer, transitional and winter periods. These behavioural data were then used to drive dynamic building performance simulation to predict the energy saving potential of changing behaviour. Comparison with predicted results by assumed behavioural patterns reflected that improperly assumed behavioural patterns may either overestimate or underestimate the energy saving potential of changing behaviour, especially for unextreme behaviours.

  • 39. Pan, Song
    et al.
    Wang, Xinru
    Wei, Yixuan
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Gál, Csilla V
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Rend, Guangying
    Yan, Da
    Yong, Shi
    Wu, Jinshun
    Liu, Jiaping
    Cluster analysis for occupant-behavior based electricity load patterns in buildings: a case study in Shanghai residences2017In: Building Simulation, ISSN 1996-3599, E-ISSN 1996-8744, Vol. 10, no 6, p. 889-898Article in journal (Refereed)
    Abstract [en]

    In building performance simulation, occupant behavior contributes to large uncertainties, which often lead to considerable discrepancies between actual energy consumption and simulation results. This paper aims to extract occupant-behavior related electricity load patterns using classical K-means clustering approach at the initial investigation stage. Smart-metering data from a case study in Shanghai, China, was used for the load pattern analysis. The electricity load patterns of occupants were examined on a daily/weekly/seasonal basis. According to their load patterns, occupants were categorized as (a) white-collar workers, (b) poor or older families and (c) rich or young families. The daily patterns indicated that electricity use was much more random and fluctuated over a wide range. Most households of the monitored communities consumed relatively-low electricity; the characteristic double peak with higher level of consumption in the morning and evening were only apparent in a relatively small subset of residents (mostly white-collar workers). The weekly analysis found that significant load shifting towards weekend days occurred in the poor or old family group. The electricity saving potential was greatest in the white-collar workers and the rich or young family groups. This study concludes with recommendations to stakeholders utilizing our load profiling results. The research provides a rare insight into the electricity-use-related occupant behaviors of Shanghai residents through the case study of two communities. The findings of the study are also presented in a meaningful way so that they can directly aid the decision-making of governments and other stakeholders interested in energy efficiency. The research results are also relevant to the building energy simulation community as they are derived from observations, and thus can have the potential to improve the efficiency and accuracy of numerical simulation results.

  • 40. Petrovic, B.
    et al.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Wallhagen, M.
    Eriksson, O.
    Life cycle assessment of building materials for a single-family house in Sweden2019In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 158, p. 3547-3552Article in journal (Refereed)
    Abstract [en]

    The Nordic countries have shown great interest in using Life Cycle Assessment (LCA) in the building sector compared to the past years. Sweden has set up an objective to be carbon neutral (no greenhouse gas emissions to the atmosphere) by 2045. This paper presents a case study of a single-family house “Dalarnas Villa” in the region Dalarna, Sweden within a 100-year perspective. The assessment is implemented using a new software based on hard data agreed by Environmental Product Declarations (EPDs). It focuses on building materials, transport distances of the materials, and replacement of essential construction materials. The LCA in this study demonstrates the environmental impact related to building materials from production and construction phase including transport, replacement and deconstruction phase. The study does not cover energy use and water consumption. The results show that the building slab made by concrete is the part of the construction most contributing to CO2e, while the wood frame and cellulose insulation have low environmental impact. Replacement of materials takes nearly half of total environmental impact over 100 years. Having a large share of wood-based products, make greenhouse gas emissions remains low.

  • 41. Petrovic, Bojana
    et al.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Wallhagen, Marita
    Eriksson, Ola
    Life cycle assessment of a wooden single-family house in Sweden2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 251, p. 113-253, article id 113253Article in journal (Refereed)
    Abstract [en]

    To understand the reasons behind the large environmental impact from buildings the whole life cycle needs to be considered. Therefore, this study evaluates the carbon dioxide emissions in all stages of a single-family house in Sweden from the production of building materials, followed by construction and user stages until the end-of-life of the building in a life cycle assessment (LCA). The methodology applied is attributional life cycle assessment (LCA) based on ‘One Click LCA’ tool and a calculated life span of 100 years. Global warming potential (GWP) and primary energy (PE) are calculated by using specific data from the case study, furthermore the data regarding building materials are based on Environmental Product Declarations (EPDs). The results show that the selection of wood-based materials has a significantly lower impact on the carbon dioxide emissions in comparison with non-wood based materials. The total emissions for this single-family house in Sweden are 6 kg CO 2 e/m 2 /year. The production stage of building materials, including building systems and installations represent 30% of the total carbon dioxide equivalent emissions, while the maintenance and replacement part represents 37%. However, energy use during the in-use stage of the house recorded lower environmental impact (21%) due to the Swedish electricity mix that is mostly based on energy sources with low carbon dioxide emissions. The water consumption, construction and the end-of-life stages have shown minor contribution to the buildings total greenhouse gas (GHG) emissions (12%). The primary energy indicator shows the largest share in the operational phase of the house.

  • 42. Qiu, Zhongzhu
    et al.
    Zhao, Xudong
    Li, Peng
    Zhang, Xingxing
    University of Hull.
    Ali, Samira
    Tan, Junyi
    Theoretical investigation of the energy performance of a novel MPCM (Microencapsulated Phase Change Material),slurry based PV/T module2015In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 87, p. 686-698Article in journal (Refereed)
    Abstract [en]

    Aim of the paper is to present a theoretical investigation into the energy performance of a novel PV/T module that employs the MPCM (Micro-encapsulated Phase Change Material) slurry as the working fluid. This involved (1) development of a dedicated mathematical model and computer program; (2) validation of the model by using the published data; (3) prediction of the energy performance of the MPCM (Microencapsulated Phase Change Material) slurry based PV/T module; and (4) investigation of the impacts of the slurry flow state, concentration ratio, Reynolds number and slurry serpentine size onto the energy performance of the PV/T module. It was found that the established model, based on the Hottel–Whillier assumption, is able to predict the energy performance of the MPCM slurry based PV/T system at a very good accuracy, with 0.3–0.4% difference compared to a validated model. Analyses of the simulation results indicated that laminar flow is not a favorite flow state in terms of the energy efficiency of the PV/T module. Instead, turbulent flow is a desired flow state that has potential to enhance the energy performance of PV/T module. Under the turbulent flow condition, increasing the slurry concentration ratio led to the reduced PV cells' temperature and increased thermal, electrical and overall efficiency of the PV/T module, as well as increased flow resistance. As a result, the net efficiency of the PV/T module reached the peak level at the concentration ratio of 5% at a specified Reynolds number of 3,350. Remaining all other parameters fixed, increasing the diameter of the serpentine piping led to the increased slurry mass flow rate, decreased PV cells' temperature and consequently, increased thermal, electrical, overall and net efficiencies of the PV/T module. In overall, the MPCM slurry based PV/T module is a new, highly efficient solar thermal and power configuration, which has potential to help reduce fossil fuel consumption and carbon emission to the environment.

  • 43. Ren, Guangying
    et al.
    Sunikka-Blank, Minna
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    The Influence of Variation in Occupancy Pattern on Domestic Energy Simulation Prediction: A Case Study in Shanghai2017Conference paper (Refereed)
  • 44.
    Shen, Jingchun
    et al.
    Dalarna University, School of Technology and Business Studies, Construction.
    Copertaro, Benedetta
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Sangelantoni, L.
    University of L'Aquila, Italy.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Suo, H.
    Guangzhou University, Guangzhou, China.
    Guan, X.
    Guangzhou University, Guangzhou, China.
    An early-stage analysis of climate-adaptive designs for multi-family buildings under future climate scenario: Case studies in Rome, Italy and Stockholm, Sweden2020In: Journal of Building Engineering, E-ISSN 2352-7102, Vol. 27, article id 100972Article in journal (Refereed)
  • 45.
    Shen, Jingchun
    et al.
    Dalarna University, School of Technology and Business Studies, Construction.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Copertaro, Benedetta
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    An early-stage analysis of climate-adaptive designs for multi-family buildings under future climate scenario: case studies in Rome, Italy and Stockholm, Sweden2019In: Article in journal (Refereed)
    Abstract [en]

    This paper presents a preliminary case study for climate-adaptive residential multifamily building designs located in urban centre at early stage, to allow thermal comfort and minimum energy use from today to the last part of 21st century. The generated future climate data combined with comfort model assessment has been proposed as a new way including future climate scenarios in preliminary building design for two representative sites, in Rome, Italy and Stockholm, Sweden. The existing vulnerability to the expected climate conditions from psychometric analysis indicates that: (1) the climate trend in Rome would gradually lead to more failures in the majority of conventional adaptive design measures, as the cooling and dehumidification demands would rise from 5.3% to 23.6%, while the heating and humidification demands would decrease from 27% to 16%; (2) the climate trend in Stockholm would result in an increased comfort period by exploiting more adaptive design measures, since the heating and humidification demands would be reduced from 67% to 53%. However, the cooling and dehumidification demands would increase slightly from 0% to 1.5%. Accordingly, four main key risks are identified: 1) overheating would become a rising increasing public health threat for buildings in Rome that rely exclusively on natural ventilation; 2) open questions remain for the design team in the area of correct cooling load selection, additional space for the future installation and the effectiveness of current cooling device etc.; 3) occasional heat waves and gradual rising humidity levels are expected to be a vulnerable topic for conventional lightweight building in Stockholm; 4) buildings with a heavy heating load would tend to have greater cooling demand, especially those with poor ventilation resources or greater internal gains. In conclusion, it is suggested that envelope optimization, whichever climate type, is one of the most efficient and effective adaptation measures towards future climate conditions.

  • 46. Shen, Jingchun
    et al.
    Zhang, Xingxing
    He, Wei
    Xu, Peng
    Zhao, Xudong
    Design, Fabrication and Experimental Study of a Loop-heat-pipe based Solar Thermal Facade Water Heating System2015Conference paper (Refereed)
  • 47. Shen, Jingchun
    et al.
    Zhang, Xingxing
    University of Nottingham.
    Yang, Tong
    Tang, Llewellyn
    Cheshmehzangi, Ali
    Wu, Yupeng
    Huang, Guiqin
    Zhong, Dan
    Xu, Peng
    Liu, Shengchun
    Characteristic study of a novel compact Solar Thermal Facade (STF) with internally extruded pin-fin flow channel for building integration2016In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 168, p. 48-64Article in journal (Refereed)
    Abstract [en]

    The fully building integrated Solar Thermal Facade (STF) systems can become potential solutions for aesthetics architectural design, as well as for the enhancement of energy efficiency and reduction of operational cost in the contemporary built environment. As a result, this article introduces a novel compact STF with internally extruded pin–fin flow channel that is particularly suitable for the building integration. A dedicated simulation model was developed on basis of the heat transfer and the flow mechanics. A prototype of this STF was fabricated and then it was tested under a series of controlled environmental conditions. The experimental validation illustrated a good agreement with the simulation results, indicating the established model was able to predict the STF’s thermal performance at a reasonable accuracy (i.e. mean deviation of less than 5.46%). The impacts of several operational parameters, i.e. equivalent solar radiation, air temperature, air velocity, water mass flow rate and inlet water temperature, on the STF thermal performance were then discussed respectively. Given the baseline testing condition, the collector efficiency factor F′ is almost 0.9930, leading to a relatively high nominal thermal efficiency at about 63.21%, which demonstrates such STF, with simpler structure, lower cost and higher feasibility in architectural design, can achieve an equivalent or better thermal performance than recent bionic STF or the conventional ones. It is also concluded that the thermal efficiency varies proportionally with solar radiation, air temperature, and mass flow rate of water, but oppositely to air velocity and inlet water temperature. A sharp decreasing trend of this STF’s thermal efficiency against the (Tin − Ta)/I was observed under the given operational conditions, which indicates current STF design is only suitable for pool heating, domestic hot water and radiant space heating in areas/climates with warm ambient air temperature and sufficient solar radiation. The overall research results are beneficial for further design, optimization and application of such STF in various solar driven systems, including the provision of hot water, space heating/cooling, increased ventilation, or even electricity in buildings. Such STF technology has the potential to boost the building energy efficiency and literally turn the envelope into an independent energy plant, creating the possibility of solar-thermal technologies deployment in high-rise buildings.

  • 48. Shen, Jingchun
    et al.
    Zhang, Xingxing
    University of Nottingham.
    Yang, Tong
    Tang, Llewellyn
    Shinohara, Hiroyuki
    Wu, Yupeng
    Wang, Hong
    Pan, Song
    Wu, Jinshun
    Xu, Peng
    Experimental study of a compact unglazed Solar Thermal Facade (STF) for energy-efficient buildings2016In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 104, p. 3-8Article in journal (Refereed)
    Abstract [en]

    This paper presents a real-time experimental measurement of a novel compact unglazed solar thermal facade (STF) system at outdoor environment in Shanghai, China for about a whole summer week. It demonstrates the daily average solar thermal efficiency fluctuated from 40% to 45.5%. The overall result indicates the advantages of the STF with simple structure, low cost and high feasibility in architectural design for energy-efficient building application, especially at future district or city levels.

  • 49.
    Shen, Jingchun
    et al.
    University of Nottingham, Ningbo.
    Zhang, Xingxing
    University of Nottingham.
    Yang, Tong
    Tang, Llewellyn
    Shinohara, Hiroyuki
    Wu, Yupeng
    Wang, Hong
    Pan, Song
    Wu, Jinshun
    Xu, Peng
    Optimizing the configuration of a compact thermal facade module for solar renovation concept in buildings2016In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 104, p. 9-14Article in journal (Refereed)
    Abstract [en]

    Solar concepts show potentially an improved cost-performance (energy) ratio when applied as the integrated parts of building renovations. This paper reported a compact solar thermal facade (STF) module with the internally extruded flow channel suiting for solar renovation concept in buildings. A few of impact factors were considered for the parametric study in order to optimize the STF's configuration for various applications through the validated simulation model. The overall research results are expected to be useful for further improvement in the thermal performance of solar renovation measures.

  • 50.
    Shen, Jingchun
    et al.
    University of Nottingham, Ningbo.
    Zhang, Xingxing
    University of Nottingham.
    Yang, Tong
    Tang, Llewellyn
    Wu, Yupeng
    Jin, Ruoyu
    Pan, Song
    Wu, Jinshun
    Xue, Peng
    Conceptual development of a compact unglazed Solar Thermal Facade (STF) for building integration2016In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 96, p. 42-54Article in journal (Refereed)
    Abstract [en]

    This research aims to develop an initiative modular unglazed Solar Thermal Facade (STF) concept initially for hot water generation to facilitate the integration of solar energy with buildings. The new STF concept is simple structure, low cost, and aesthetically appealing with easy installation but is expected to achieve the equivalent thermal efficiency as the conventional STFs. It delivered alternative design in terms of material, colour, texture, shape, size, architectural design, installation method, array connection, hypothetical system application, and solar coverage. Two common design variants i.e. (a) the STF cladding system and (b) the prefabricated STF wall system were described respectively for existing and new low-rise building typologies. Interaction of inclination, orientation, and insolation were discussed for the optimum STF position on the building. Four currently available methods for installation of such STF with buildings were summarized and three typical array connection methods were identified. The decentralized connection was recommended for different types of STF hot water systems. It is customary to design for a solar coverage of 50 to 60 percent for water heating in detached houses; in apartment buildings 30 to 40 percent are more commonly assumed. The concept design in this paper hereby illustrates the precedence for the hypothetical function by the creation of new ideas and also forms up the physical structure or operating principle for the investigations in near future.

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