Experimental and simulation studies on the effect of suction opening orientation on solar vertical chimney

The zero energy building considered is a single storey building in Tiruchirappalli city retrofitted with various green features. This study investigated the effect of a suction opening orientation on a vertical solar chimney (VSC), integrated into a one-storey building. It was designed, manufactured and tested through selection of different suction openings for the entry of air, including right, left, front, back, both right and left and both front and back sides. Genetic algorithm (GA) calculates maximum air flow rate for a building with VSC for better suction opening, in Tiruchirappalli's dry, environmental conditions. GA is a useful technique for finding an improved suction opening specifically in the presence of a host of independent parameters which are large. The obtained results are related to fluid flow temperature distribution along the chimney, mass flow rate and air change per hour. The findings between the GA and the experimental results show sound agreement.     

建筑能耗统计方法探讨

建筑能耗统计是建筑节能的基础,但目前在建筑能耗的统计对象、能源种类、建筑分类等具体问题上存在模糊和争议,缺乏准确的建筑能源消耗统计数据。本文基于公开资料,研究提出适合我国国情的建筑分类方法和建筑终端能源消耗统计方法,并给出较为准确的我国当前建筑能耗数据。     

不同扩散体对建筑增强型垂直轴风力机气动性能的影响

为研究不同建筑扩散体对建筑增强型直线翼垂直轴风力机的气动性能与流场结构的影响,采用CFD数值模拟的方法,以NACA0021为叶片翼型的多叶片建筑增强型直线翼垂直轴风力机为对象,研究其在不同建筑扩散体及不同尖速比下的气动性能。结果表明:建筑增强型直线翼垂直轴风力机存在最佳尖速比;不同建筑扩散体对提高直线翼垂直轴风力机风能利用率影响较大,在所选取的8种建筑扩散体模型中,梯形建筑扩散体下的直线翼垂直轴风力机在尖速比为4.62时标准化风能利用率可达1.560 7,而A1翼型式建筑扩散体下的直线翼垂直轴风力机前后压差较小,风能难以利用。     

THE HIGH-RISE OPPOSING FACADE IN CLEAR SKY CONDITIONS—NOT ALWAYS AN “OBSTRUCTION” TO DAYLIGHT

The opposing building facade is an omnipresent feature for buildings in the urban commercial setting. In clear sky conditions, there are large surfaces of building facades that have the potential of reflecting sunlight incident on them. When the sun is behind a building (so that the solar facade azimuth is greater than 90°), the building opposite potentially acts as a passive daylighting device to it. The work discussed in this paper shows that the performance of this device varies for each floor and for different building densities. Using the ADELINE simulation software, a street with high rise buildings opposite each other is modelled in clear skies, and daylighting is calculated in rooms at different floor levels. Comparisons are made with daylighting of the same rooms without an obstructing building in order to observe the effect of the “obstructing building” to daylighting. Preliminary results indicate that the opposite facade of high rise buildings has the potential to be considered a passive daylighting device in particular contexts. As a passive device, the opposing facade could be given attention by urban designers and planners, as well as by those drawing up building legislation for the urban built environment. It would be desirable and important for users of the built environment, to determine future developments from the point of view of how opposing facades affect daylighting. This approach could have implications for energy efficiency and conservation and would utilise the free resource of solar radiation more effectively.     

Comparison of energy and exergy analysis of fossil plant,ground and air source heat pump building heating system

The energy and exergy flow for a space heating systems of a typical residential building of natural ventilation system with different heat generation plants have been modeled and compared. The aim of this comparison is to demonstrate which system leads to an efficient conversion and supply of energy/exergy within a building system.The analysis of a fossil plant heating system has been done with a typical building simulation software IDA–ICE. A zone model of a building with natural ventilation is considered and heat is being supplied by condensing boiler. The same zone model is applied for other cases of building heating systems where power generation plants are considered as ground and air source heat pumps at different operating conditions. Since there is no inbuilt simulation model for heat pumps in IDA–ICE, different COP curves of the earlier studies of heat pumps are taken into account for the evaluation of the heat pump input and output energy.The outcome of the energy and exergy flow analysis revealed that the ground source heat pump heating system is better than air source heat pump or conventional heating system. The realistic and efficient system in this study “ground source heat pump with condenser inlet temperature 30 °C and varying evaporator inlet temperature” has roughly 25% less demand of absolute primary energy and exergy whereas about 50% high overall primary coefficient of performance and overall primary exergy efficiency than base case (conventional system). The consequence of low absolute energy and exergy demands and high efficiencies lead to a sustainable building heating system.     

German and Norwegian policy approach to residential buildings’ energy efficiency—a comparative assessment

Buildings in private and domestic use are responsible for about 30% of the global greenhouse gas emissions attributable mainly to their need for heating and cooling energy. This corresponds to about 40% of the global final energy consumption. Therefore, a viable implementation of building energy efficiency policies is inevitable to realize a transformation of the energy system to mitigate climate change. Within the building sector lies a huge potential for emission reduction consisting in the renovation of the existing building stock and climate-friendly building guidelines applicable to new constructions, both adapting CO₂-neutral technology solutions. However, as there are several different pathways leading to a decarbonized energy system, there is always the question which political and technological solutions are most efficient, effective, and feasible. This paper aims to analyze building efficiency policy measures and instruments and the related technological solutions in two front-runner countries of the energy transition, possessing different structural conditions: Germany and Norway. We hence apply a comparative approach which allows us to present and assess the policies in place. The paper answers three research questions: (1) Which policies prevail in Germany and Norway to foster the deployment of energy efficient and decarbonized solutions for residential buildings? (2) How do these policies respond to country-specific barriers to the energy transition in the building sector, and (3) What effects do they have on the actual implementation of technological and societal solutions? This research provides a new insight to the highly relevant topic of energy efficiency in buildings in the context of international Intended Nationally Determined Contribution benchmarking and discusses some unsolved trade-offs in the translation of the global climate governance into the national building sector.     

350 MW机组主厂房布置优化分析

介绍了目前火力发电厂350 MW等级机组主厂房布置几种主要方案,分析了主厂房布置方案的设计思路、优化原则,提出优化建议;对主厂房布置进行模块化设计,通过对汽机房、锅炉房布置的优化、比选、组合,根据不同的情况得出最佳组合方式,以降低主厂房容积。分析表明:四大管道重量,减少建设周期和投资造价;经过综合比较,对于350 MW等级机组的主厂房布置,联合侧煤仓布置方案在主厂房容积、投资造价方面均具有明显的优势,最后以“华能荆门一期(2×350 MW)热电联产工程”为例,介绍了联合侧煤仓布置方案的优化过程。     

上海某图书馆建筑内外遮阳负荷研究

针对上海某图书馆建筑内外遮阳,采用计算法进行负荷计算,通过结果分析得到此图书馆在计算时刻下的日最大负荷值。从中可以看出除北向外,外遮阳都有不同程度的节能效果,而北向由于窗口不受太阳直射,没有遮阳效果;内遮阳的节能效果都随着材料的遮阳系数增加而增加。最后进行内外遮阳效果的对比,得到东、西向随遮阳板挑出长度增加,外遮阳节能效果更为显著;南向和北向以遮阳材料系数为0．5的内遮阳为佳。     

Energy and exergy analysis of fossil plant and heat pump building heating system at two different dead-state temperatures

In this paper, we deal with the energy and exergy analysis of a fossil plant and ground and air source heat pump building heating system at two different dead-state temperatures. A zone model of a building with natural ventilation is considered and heat is being supplied by condensing boiler. The same zone model is applied for heat pump building heating system. Since energy and exergy demand are key parameters to see which system is efficient at what reference temperature, we did a study on the influence of energy and exergy efficiencies. In this regard, a commercial software package IDA-ICE program is used for calculation of fossil plant heating system, however, there is no inbuilt simulation model for heat pumps in IDA-ICE, different COP (coefficient of performance) curves of the earlier studies of heat pumps are taken into account for the evaluation of the heat pump input and output energy. The outcome of the energy and exergy flow analysis at two different dead-state temperatures revealed that the ground source heat pumps with ambient reference have better performance against all ground reference systems as well as fossil plant (conventional system) and air source heat pumps with ambient reference.     

A critical appraisal of energy-signature models

The use of different energy-signature (ES) models for energy consumption predictions and building parameter estimations is reviewed. For predictions using time-steps of one day or longer, static ES models are found to be useful. Recommendations for the choice of model are given. The use of ES models for the estimation of building parameters, e.g. for an energy audit, should only be done with great caution, as there can be considerable errors. The development of more sophisticated dynamic models may solve some of the problems encountered with the static models discussed here.     

Evaluation of control strategies for different smart window combinations using computer simulations

Several studies have shown that the use of switchable windows could lower the energy consumption of buildings. Since the main function of windows is to provide daylight and visual contact with the external world, high visible transmittance is needed. From an energy perspective it is always best to have the windows in their low-transparent state whenever there are cooling needs, but this is generally not preferable from a daylight and visual contact point of view. Therefore a control system, which can be based on user presence, is needed in connection with switchable windows. In this study the heating and cooling needs of the building, using different control mechanisms were evaluated. This was done for different locations and for different combinations of switchable windows, using electrochromic glazing in combination with either low-e or solar control glazing. Four control mechanisms were investigated; one that only optimizes the window to lower the need for heating and cooling, one that assumes that the office is in use during the daytime, one based on user presence and one limiting the perpendicular component of the incident solar irradiation to avoid glare and too strong daylight. The control mechanisms were compared using computer simulations. A simplified approach based on the balance temperature concept was used instead of performing complete building simulations. The results show that an occupancy-based control system is clearly beneficial and also that the best way to combine the panes in the switchable window differs depending on the balance temperature of the building and on the climate. It is also shown that it can be beneficial to have different window combinations for different orientations.     

Analysis and optimization of the heat-insulating light concrete hollow brick walls design by the finite element method

Department of Public Works, owners and building proprietors are demanding high-capacity heat-insulating exterior masonry components specifically for further energy savings. For housing and industrial structures there is also a great interest in light building materials with good physical material behaviour, with respect to an energy conscious and ecological design, which fulfils all strength and serviceability requirements. The major variables influencing the thermal conductivity of masonry materials are illustrated in this work by taking blocks made from no-fine lightweight concrete and different mortar properties. The finite element method (FEM) is used for finding accurate solutions of the heat transfer equation for five different light concrete hollow brick walls. Mathematically, the non-linearity is due to the radiation boundary condition inside the inner recesses of the bricks. The conduction and convection phenomena are taking into account in this study for three different values of the mortar conductivity and three different values for the bricks. Optimization of the walls is carried out from the finite element analysis of five hollow brick geometries by means of the mass overall thermal efficiency and the equivalent thermal conductivity. Finally, conclusions of this work are exposed.     

A sensitivity analysis of a cost optimality study on the energy retrofit of a single-family reference building in Portugal

Improvement of the energy efficiency of residential buildings must ensure compliance with cost optimality criteria, assuming a specific lifespan of the building. At the same time, the energy retrofit of buildings ought to preserve their intrinsic architectural and heritage value. Portuguese residential buildings constructed before 1960 did not follow any energy efficiency rules. They represent 29% of the housing stock in the country and there is a high potential for increasing their energy efficiency. However, it costs more to implement envelope energy efficiency measures through retrofitting works than to provide for them in new buildings. An evaluation based on cost optimality criteria should therefore be performed. This work evaluates the energy performance of a Portuguese reference building typical of the pre-1960 building stock for different thicknesses of thermal insulation retrofit solutions (roof, facade, and ground floor) and systems. The study describes a sensitivity analysis that took a range of climate data, intervention costs, energy prices, discount rates, and energy needs into account. An energy needs factor dealt with the occupants’ habits and the effective reduction of energy consumption compared with the estimated energy needs.     

基于CIM的配电网综合采集应用平台

根据标准化、集成化、平台化的发展方向,结合配电网各应用系统的建设现状和应用需求,提出了配电网综合采集应用平台的建设思想。重点对该平台建设的3个主要问题进行了研究,即基于CIM建设标准的配电网底层模型．基于规约库和统一任务调度实现数据的集中采集及处理．基于权限实现配变监控、线损分析、电压统计等配电网数据的综合应用等．     

Temperature and power consumption measurements as a means for evaluating building thermal performance

A simple methodology is introduced to obtain an empirical relation between power consumption and indoor–outdoor temperature variations for a small residential building. The effects of house occupants, air/moisture leakage, material deterioration, etc. were not considered in the analysis. The Tuskegee Healthy House was used as a test building for the experiment. Empirical equations for power consumption as a function of temperature area differences were obtained from the measured data of winter 2009 with and without mechanically-induced ventilation fresh air, i.e. using fan “ON” and fan “OFF” condition, respectively. The equations were applied to the measured temperature data of winter 2002 to compare and evaluate the thermal performance of the test house. The equations agree favorably with the winter 2002 data revealing that there is no significant difference in power consumption values of winter 2002 and winter 2009 and, hence, no appreciable change in the thermal performance of the house. The methodology presented in the work can be utilized to compare and evaluate the thermal performance of a given building envelope from season to season and between the same seasons in different years.     

Simulating the thermal behaviour of a building during summer period in the urban environment

In this study an attempt is made to investigate the impact of the urban heat island (UHI) effect on the energy consumption of a building using both, an accurate, extensively validated, transient simulation model and a neural network one. The energy consumption is calculated for a typical building during the summer period at 20 different sites of the Greater Athens area with the aid of the TRNSYS model. It was found that the UHI affects significantly the thermal behaviour of the building, implying much lower cooling load cost and energy cost in the suburban areas. A neural network model was then appropriately designed and tested for the estimation of the energy consumption, employing as an input, the UHI intensity. The results of both methods were tested and compared and it was found that there is a good agreement between the cooling rate values calculated by the TRNSYS programme and those derived by the neural model. Moreover, the employment of the neural model helped in quantifying the contribution of each input parameter in the calculation of the cooling rate, and it was demonstrated that the UHI effect is a predominant parameter, affecting considerably the energy consumption of a building in the Mediterranean region.     

某智能大厦空调系统冷源方案比较

对某智能大厦空调系统冷源方案—水冷冷水机组与风冷冷水机组，分别从设备性能数据、设备初投资、全年运行维护费用、补水量、制冷性能、震动和噪声等方面进行比较。指出两种方案技术经济性比较相当，但由于群楼屋面未能提供足够空间放置风冷冷水机组，最终选用水冷冷水机组作为本项目的冷源方案。     

The development and utilization of microgrid technologies in China

The paper introduced the concept of a multilevel microgrid (MG), which starts at the building level and creates an MG at this level. The development process of MG in China was described in detail for the first time, including the key issues and the research direction. The prediction error and uncertainty analysis of wind power, photovoltaic power generation, load, and controllable generator components are given, respectively. The uncertainty distribution model is helpful to construct the objective function of minimizing the operating cost of MG. First, an hypothetical apartment building’s suitability for installation of solar panels, wind turbines, and solar thermal devices in Shanghai was analyzed, including the principles and characteristics of their electrical generation and energy collection. Compared to the analysis of a single building, the results are more comprehensive for simulating the loading of different buildings in a variety of situations. The mathematical model of peak load shaving in an MG was constructed, and the interior-point method was used to solve it. By simulation analysis, the variation of load curve and related parameters before and after peak load shaving was obtained. First, the average loading of an office building with and without the MG was compared, and the reduction rate in peak loading of a building was used to analyze whether there was additional storage and found the change rule. A neighborhood with the additional MG technologies and additional storage units is better than other existing literature in showing the effectiveness of peak- load reduction.     

Determination of optimum insulation thicknesses of the external walls and roof (ceiling) for Turkey's different degree-day regions

The external walls and roof of a building are the interface between its interior and the outdoor environment. Insulation of the external walls and roof is the most cost-effective way of controlling the outside elements to make homes more comfortable. Although insulation is generally accepted as a factor increasing the building costs, with the calculations we have shown that this is not the case. Fuel consumption and operational costs are reduced by increasing the thickness of the external walls and roof (ceiling), despite an increase in the investment costs. According to Turkish Standard Number 825 (TS 825), there are four different degree-day (DD) regions, and the required heat loads for the buildings in these regions exhibit large differences. Therefore, a method based on costs is needed for the determination of optimum insulation thicknesses of different DD regions. In this study, optimum insulation thicknesses for different DD regions of Turkey, namely, Izmir (DD: 1450), Bursa (DD: 2203), Eski?ehir (DD: 3215) and Erzurum (DD: 4856), have been determined for a lifetime of N years, maximizing the present worth value of annual energy savings for insulated external walls.