This study proposed a decomposition method based on the normalized quadratic shadow unit cost function to explore the determinants of the change in energy intensity in China from 1985 to 2010.The decomposition analysi...This study proposed a decomposition method based on the normalized quadratic shadow unit cost function to explore the determinants of the change in energy intensity in China from 1985 to 2010.The decomposition analysis indicates that (1) the improvement in technical efficiency dramatically reduced the energy intensity,whereas technological change played only a minor role,which could be attributed to a rebound effect;(2) the aggregated allocation effect was small because the change in the allocative distortion between capital and energy significantly enhanced energy intensity but was partly offset by the effect stemming from the change in the allocative distortion between capital and energy;and (3) the substitution of energy for labor increased energy intensity,but the aggregated substitution effect significantly reduced energy intensity because the substitution of capital for energy reduced energy intensity to a great extent.These findings were obtained at the national level and varied at die regional level.展开更多
相变材料(Phase change material,PCM)在建筑围护结构中的应用是一种改善室内热环境和居住舒适度的有效方法。为探索相变材料在夏热冬冷地区应用的节能潜力,对比研究了不同相变材料应用方法的节能效果,以能源使用强度(Energy use intens...相变材料(Phase change material,PCM)在建筑围护结构中的应用是一种改善室内热环境和居住舒适度的有效方法。为探索相变材料在夏热冬冷地区应用的节能潜力,对比研究了不同相变材料应用方法的节能效果,以能源使用强度(Energy use intensity,EUI)评价不同应用方法的建筑性能,旨在找出最优的应用方法。所用的相变材料以高密度聚乙烯球封装,并嵌入在XPS保温板中,形成XPSPCM板。研究结果表明:在制冷季,将XPSPCM板安装在建筑物墙体内表面时的EUI比其装在建筑物墙体外表面时降低了0.27~0.66kWh/m2,采暖季的降低幅度为0.68~0.88kWh/m2。综合考虑全年工况时,当XPSPCM板安装至建筑物墙体靠近内表面时EUI值最小。以EUI雷达图对比XPSPCM板集中于建筑不同朝向的应用效果,结果显示对于熔点为25℃的相变材料,相变材料集中布置于西向外墙时时建筑能耗最低。展开更多
The use of phase change materials(PCMs)in building enclosures is an efficient way to reduce the heat gain and/or loss in summer and winter.It was evident that the thermal performance of buildings with PCMs was affecte...The use of phase change materials(PCMs)in building enclosures is an efficient way to reduce the heat gain and/or loss in summer and winter.It was evident that the thermal performance of buildings with PCMs was affected by the outdoor air temperature significantly.However,the influence of humidity,which was serious in the humid subtropical climate was unclear.To explore the effect of PCMs under a humid subtropical climate,the thermal performance of a lightweight building outfitted with PCMs with a melting temperature of 25°C was investigated.The actual outdoor air temperature with a humidity of 40-90 RH%and wind velocity of 2-6 m/s blowing from the east,west,south,and north was assumed for the performance assessment.A simulated model was developed using EnergyPlus and verified against experimental data.The energy savings by using PCMs was reduced from 3.9%to 2.6%when the outdoor humidity increased from 40 to 90 RH%in summer.However,the savings was not obvious in winter.Annual energy savings decreased from 1.64%to 1.32%with humidity increasing from 40 to 90 RH%.For annual condition,the average energy savings was reduced from 1.43%to 0.92%when the wind speed increased from 2 m/s to 6 m/s.From an economic point of view,the investment payback period was less than 10 years when the PCM price was lower than 18.0 Yuan/kg.展开更多
基金the National Natural Science Foundation of China(grant number 71203018)the Humanities and Social Sciences Fund of the Ministry of Education(grant number 12YJC790248)the Fundamental Research Funds for the Central Universities for their support
文摘This study proposed a decomposition method based on the normalized quadratic shadow unit cost function to explore the determinants of the change in energy intensity in China from 1985 to 2010.The decomposition analysis indicates that (1) the improvement in technical efficiency dramatically reduced the energy intensity,whereas technological change played only a minor role,which could be attributed to a rebound effect;(2) the aggregated allocation effect was small because the change in the allocative distortion between capital and energy significantly enhanced energy intensity but was partly offset by the effect stemming from the change in the allocative distortion between capital and energy;and (3) the substitution of energy for labor increased energy intensity,but the aggregated substitution effect significantly reduced energy intensity because the substitution of capital for energy reduced energy intensity to a great extent.These findings were obtained at the national level and varied at die regional level.
文摘相变材料(Phase change material,PCM)在建筑围护结构中的应用是一种改善室内热环境和居住舒适度的有效方法。为探索相变材料在夏热冬冷地区应用的节能潜力,对比研究了不同相变材料应用方法的节能效果,以能源使用强度(Energy use intensity,EUI)评价不同应用方法的建筑性能,旨在找出最优的应用方法。所用的相变材料以高密度聚乙烯球封装,并嵌入在XPS保温板中,形成XPSPCM板。研究结果表明:在制冷季,将XPSPCM板安装在建筑物墙体内表面时的EUI比其装在建筑物墙体外表面时降低了0.27~0.66kWh/m2,采暖季的降低幅度为0.68~0.88kWh/m2。综合考虑全年工况时,当XPSPCM板安装至建筑物墙体靠近内表面时EUI值最小。以EUI雷达图对比XPSPCM板集中于建筑不同朝向的应用效果,结果显示对于熔点为25℃的相变材料,相变材料集中布置于西向外墙时时建筑能耗最低。
基金This work was supported by the National Key R&D Plan(2018YFE0111200)National Natural Science Foundation of China(52078053,51308051)+2 种基金the Science and Technology Department of Hunan(2019JJ30027)Hunan Association for Science and Technology(2017TJQ05)the C hangsha City Fund for Distinguished and Innovative Young Scholars(kq1905038).
文摘The use of phase change materials(PCMs)in building enclosures is an efficient way to reduce the heat gain and/or loss in summer and winter.It was evident that the thermal performance of buildings with PCMs was affected by the outdoor air temperature significantly.However,the influence of humidity,which was serious in the humid subtropical climate was unclear.To explore the effect of PCMs under a humid subtropical climate,the thermal performance of a lightweight building outfitted with PCMs with a melting temperature of 25°C was investigated.The actual outdoor air temperature with a humidity of 40-90 RH%and wind velocity of 2-6 m/s blowing from the east,west,south,and north was assumed for the performance assessment.A simulated model was developed using EnergyPlus and verified against experimental data.The energy savings by using PCMs was reduced from 3.9%to 2.6%when the outdoor humidity increased from 40 to 90 RH%in summer.However,the savings was not obvious in winter.Annual energy savings decreased from 1.64%to 1.32%with humidity increasing from 40 to 90 RH%.For annual condition,the average energy savings was reduced from 1.43%to 0.92%when the wind speed increased from 2 m/s to 6 m/s.From an economic point of view,the investment payback period was less than 10 years when the PCM price was lower than 18.0 Yuan/kg.
