Strategy for designing more energy efficient chiller plants serving air-conditioned buildings

In cities located in the subtropical regions, air-cooled chillers are commonly used to cool commercial buildings almost year-round, which accounts for considerable electricity consumption in the long term. This paper explains how a chiller plant should be designed to enable the chillers to operate frequently with maximum performance. Four design options with respect to the number and size of chillers were studied for a chiller plant satisfying the year-round cooling demand of a hotel. For each design option, the annual electricity consumption of chillers and pumps was assessed using a sophisticated chiller model. The assessment showed that an electricity saving of 10.1% can be achieved by installing a chiller plant with six chillers of three different sizes instead of four equally sized chillers. The results of this paper will give engineers and researchers a better idea about how to select chillers of different sizes and how chiller part load performance curves can be used to evaluate improvements in the energy performance of a chiller plant with alternative designs.     

Modelling of the coefficient of performance of an air-cooled screw chiller with variable speed condenser fans

Air-cooled chillers are generally recognized as energy intensive equipment in air-conditioned buildings in the subtropical climate. This paper considers how the use of variable speed condenser fans enables these chillers to operate more efficiently. The thermodynamic model of an air-cooled screw chiller was developed using the simulation program TRNSYS and validated using the field data and specifications of the chiller. The staging of condenser fans and the control of their speed in various operating conditions were described. A comparison was made on the coefficient of performance of the chiller in the steady state with various control strategies: head pressure control with constant or variable speed condenser fans; condensing temperature control (CTC) with constant or variable speed condenser fans. Potential improvements in the chiller COP due to the use of CTC with variable speed condenser fans were discussed. The findings of this paper are useful in developing more energy efficient air-cooled chillers.     

Explaining the adoption of energy-efficient technologies in U.S. commercial buildings

This paper investigates factors explaining the adoption of energy-efficient heating, cooling, window, and lighting technologies in U.S. commercial buildings. It presents multinomial logit models of technology adoption using the 2003 Commercial Buildings Energy Consumption Survey microdata set, examining, first, fundamental building components, and, second, energy-efficient adaptations. Key findings are that the choice of fundamental building components is strongly influenced by locational factors, the activities that are expected to take place in the building, and building-specific characteristics. Lighting technologies are an exception, and are poorly explained by these factors. By contrast, energy-efficient heating, cooling, window, lighting, and control adaptations appear to share common drivers, and are more likely to be adopted in newer, larger, more energy-intensive, owner-occupied buildings. These are the buildings that can best afford the up-front costs of innovation, which is often a design-intensive process. Absent policy interventions, the energy-efficient adaptations are unlikely to diffuse rapidly to the rest of the commercial building stock.     

An alternative approach for the performance rating of air-cooled chillers used in air-conditioned buildings

Air-cooled chillers are widely used to provide cooling energy for air-conditioned buildings at the expense of considerable electricity. The (Air-Conditioning & Refrigeration Institute) ARI standard 550/590 sets out a rating condition to specify the coefficient of performance (COP) of the chillers under part-load conditions. This condition was found to be insufficient to deal with diverse operating conditions under the multiple chiller arrangement. This paper proposes an alternative approach to specifying more precisely the chiller COP under part-load conditions. It is desirable to establish a set of part-load performance curves showing how the chiller COP varies with the condensing temperature at various combinations of chiller loads and outdoor temperatures. The results of this paper will give engineers and researchers a better idea about how to specify the upper limit of condensing temperature for more energy efficient chillers and how chiller COP curves help compare air-cooled chillers for buildings in any climate zone and to estimate the annual electricity consumption of chillers satisfying any given building cooling load profile.     

风冷热泵冷水机组用于高层建筑的空调设计

介绍了深圳一高层建筑的空调设计概况以及风冷热泵冷水机组机房的设计安装。分析了工程安装调试中出现的机房温度过高的原因,提出并通过评估确定了最佳的解决方案。     

批发市场商业建筑性能化防火设计浅谈

通过对西安某批发市场的防火疏散调查研究,了解了批发市场商业建筑的防火设计问题,主要内容包括设计火灾荷载、火灾场景设定、热释放率（HRR）、FDS防火软件的应用、日本疏散经验公式等,通过对上述内容的不同方法的运用。对结果进行了对比研究,从而研究现调查的批发市场商业建筑的防火疏散能力。     

An integrated performance assessment framework for water treatment plants

An innovative framework for the performance assessment of a traditional water treatment plant (WTP) is presented that integrates the concepts of reliability, robustness, and Quantitative Microbial Risk Assessment (QMRA). Performance assessment for a WTP comprised of three units (i.e., unit 1: Coagulation/Flocculation and Sedimentation; unit 2: Filtration, and unit 3: Disinfection) was conducted. Performance functions for units 1, 2, and units 1 and 2 combined, were constructed by integrating turbidity robustness indices. Performance function for chlorine disinfection was developed based on the difference between achieved and required CT values. A health-based performance function was developed by comparing the target daily infection rate to the site-specific infection rate. It was used to identify whether the health-based target was met during the failures of units 1 to 3. Results obtained from the proposed performance functions can be used by operators to ensure that multiple barriers perform successfully under variable conditions.     

Peak load characteristics of Sydney office buildings and policy recommendations for peak load reduction

Growth in peak period electricity demand has driven the requirement for a significant expansion of Sydney's electricity network. Energy efficiency and demand management activities in office buildings may be an alternative to electricity network augmentation, with significant economic and environmental benefits. This paper identifies and characterises trends in electricity peak demand in Sydney's office buildings, comparing a range of high and low energy consuming buildings. The paper assesses the potential for energy efficiency and demand management strategies in office buildings to reduce peak loads and hence defer electricity network augmentation. Base building electricity load data was analysed for a sample of 25 Sydney office buildings, along with Sydney electricity substation and temperature data. Peak loads for buildings with best practice energy performance were found to be 26% lower than for buildings with average energy performance, while annual electricity consumption was 57% lower. With these findings, this paper has assessed the effectiveness of current energy efficiency policy for peak demand management and has recommended strengthening energy efficiency policies in order to capture coincidental peak load reductions, as well as new policies specifically targeting peak demand management. It was found that these measures could offer significant potential to defer network investment.     

Development of envelope efficiency labels for commercial buildings: Effect of different variables on electricity consumption

After the first federal law on energy efficiency was published in 2001, the Brazilian government promoted several actions on energy efficiency, including the Federal Regulation for Voluntary Labeling of Energy Efficiency Levels in Commercial, Public and Service Buildings. Divided into three parts, lighting system, HVAC and building envelope, it is expected to become mandatory in 2013. This paper describes the criteria adopted to evaluate the envelope efficiency level, focusing on the development of a regression equation which provides an electricity consumption indicator. The envelope label is divided into five efficiency levels, from A (more efficient) to E (less efficient), identified according to the electricity consumption indicator. The linear regression equation considers variables such as window to wall ratio (WWR), SHGC, solar protection angles, building volume indicators and the roof U_value. The U_value of the walls was excluded from the equation due to its non-linearity. Its relation with electricity consumption depends on internal gains, exterior temperatures, building size and thermal capacity of the walls and could not be described by a linear regression equation. Some limitations were identified and shape factor limits were provided. The envelope efficiency label is obtained by the comparison of the electricity consumption indicator of the proposed building with the electricity consumption indicators of two other building envelopes presented.     

Energy efficiency benchmarks and the performance of LEED rated buildings for Information Technology facilities in Bangalore, India

This paper provides a summary of an energy benchmarking study that uses performance data of a sample of Information Technology facilities in Bangalore. Information provided by the sample of occupiers was used to develop an Energy Performance Index (EPI) and an Annual Average hourly Energy Performance Index (AAhEPI), which takes into account the variations in operation hours and days for these facilities. The EPI and AAhEPI were modelled to identify the factors that influence energy efficiency. Employment density, size of facility, operating hours per week, type of chiller and age of facility were found to be significant factors in regression models with EPI and AAhEPI as dependent variables. Employment density, size of facility and operating hours per week were standardised and used in a separate regression analysis. Parameter estimates from this regression were used to normalize the EPI and AAhEPI for variance in the independent variables. Three benchmark ranges - the bottom third, middle third and top third - were developed for the two normalised indices. The normalised EPI and AAhEPI of LEED rated building, which were also part of the sample, indicate that, on average, LEED rated buildings outperform the other buildings.     

商业建筑火灾场景设计的试验研究

当前,建筑防火设计规范向性能化方向发展。性能化防火设计所做的主要工作是火灾风险评估,而火灾场景设计是火灾风险评估的基础。以火灾荷载调查数据为基础进行典型商业建筑火灾场景设计的试验研究,设计大型购物中心内快餐店和运动休闲店两类店铺的燃料包并进行ISO 9705实体房间火试验,用于确定燃料包的燃烧特性,如热释放速率、毒性气体产生速率等。试验结果表明:快餐店和运动休闲店两个燃料包的火灾增长率处于中速火和快速火之间,并且偏向于快速火,两个试验的热释放速率的峰值都达到1MW左右,平均热释放速率快餐店为139kW,运动休闲店为191kW。试验结果可以为建筑设计师和消防工程师在火灾风险评估中设计火灾场景提供参考。     

An ETTV-based approach to improving the energy performance of commercial buildings

This paper aims to study the various parameters that affect the energy performance of commercial buildings in Singapore. The parameters are diverse, ranging from characteristics of construction of the walls and windows, to the various system settings and types within the building. Building energy performance is measured via two key indexes, namely, the Envelope Thermal Transfer Value (ETTV) and the annual cooling energy requirement (E_c). Parameters related to these two indexes are identified. An additional parameter, the solar absorptance of the wall, is further incorporated to calibrate the ETTV equation. A relative ranking on the functional parameters of ETTV has been performed to evaluate their effectiveness in lowering the ETTV of buildings. In addition, the impact of using cladding on ETTV is also studied. A correlation for E_c, expressed in the form of a simple linear equation, has been developed. This correlation accounts for the internal building loads, envelope loads, operating schedules and efficiency of the cooling equipment. Finally, ETTV and E_c have been employed to study the effects of chiller over-sizing and ventilation rates on building cooling energy. In the pursuit for better energy-efficient buildings, the approach presented in this paper contributes to the construct of sustainable energy-efficient built-environment.     

A systematic methodology for optimising the energy performance of buildings in Bahrain

Today, a great deal of effort is ongoing all over the world to find methods for optimising the energy performance of buildings. Such efforts can be seen in the European Energy Performance of Building Directive (EPBD). This directive aims to ensure energy saving and CO₂ emission reduction without compromising the local conditions and people's comfort. In the Gulf States, however, there is a need for such methods due to their economic and environmental benefits. This study introduces a simple but reliable methodology for optimising building energy performance in Bahrain. The methodology is based on building management systems (monitoring, analysing and targeting future performance), simulation tools and other technologies. This methodology was implemented using Visual DOE and was directly related to collectively gathered data gained form experimental works and practical applications. By means of the introduced methodology, energy consumption was obtained together with energy cost and CO₂ emissions. The applicability of this methodology was demonstrated through optimising a case office building in Bahrain.     

Optimization of the management of building stocks: An example of the application of managing heating systems in university buildings in Spain

The article presents the implementation of management measures that have reduced the gas consumption for space heating of a university building in Spain by 40%. The measures affect the use of the building, e.g., the use of its spaces, and the scheduling of its occupancy. They also affect the management of the heating system: a protocol for turning the system on and shutting it off has been developed.The work is part of a framework for action by the Technical University of Catalonia covering more areas and for a longer period of time, in which policies have been designed for managing buildings and a number of studies have been developed on the energy consumption of the university's buildings. The article highlights the work methodology proposed to achieve the energy savings calculated theoretically in a previous study. The implementation of these measures in the case, from November 2006 until May 2007, has reduced consumption from 113.2 kWh/m² to 68.7 kWh/m² a year; thus, the hypothesis has been validated. In addition, it was possible to examine methodological details more closely. Finally, the relationship between the people involved in the process (the building owners, managers and energy users) is a determining factor.     

关于建筑抗震设计最小地震剪力系数的讨论

介绍了GB 50011-2010《建筑抗震设计规范》关于楼层最小地震剪力系数规定的编写背景,及其与其他国家规范的相关规定的区别。论述了结构的最小地震剪力系数（剪重比）与设防烈度、场地特征周期、结构周期、振型、阻尼比等参数的关系。列举了位于不同地区（沿海和内地）、不同高度的超高层建筑设计,说明由于地震作用和风荷载不同,计算的楼层地震剪力系数、层间位移及墙、柱等构件轴压比也会不同。结构对地震作用与风荷载的反应不同,设计应区别对待。只要设计合理,大多数结构的最小地震剪力系数可以满足规范要求。对一幢超高层建筑结构进行全面剖析,综合比较,论证了各类参数之间的关系,证明我国规范关于楼层最小地震剪力系数的规定不但是必要的,也是合理可行的。     

Analysis and optimization of the use of CHP-ORC systems for small commercial buildings

The use of combined heating and power (CHP) systems is increasing rapidly due to their high potential of reducing primary energy consumption (PEC), cost, and carbon dioxide emissions (CDE). These reductions are mainly due to capturing the exhaust heat to satisfy the thermal demand of a building. However, when the CHP system is operated following the electric load, the recovered exhaust heat may or may not be sufficient to satisfy the thermal demand of the facility. When the recovered exhaust heat is more than the heat required, the excess is usually discarded to the atmosphere. An organic rankine cycle (ORC) can be used to recover the surplus exhaust heat to generate extra electricity. Therefore, combining the ORC system with the CHP system (CHP-ORC) reduces the electricity that has to be produced by the CHP system, thereby reducing the total PEC, cost, and CDE. The objective of this paper is to study the energetic, economical, and environmental performance of a combined CHP-ORC system and compare its performance to a standalone CHP system and a reference building for different climate zones. A comparison of a CHP-ORC system operating 24 h with a system operating during typical office hours is also performed.     

An experience on integrating monitoring and simulation tools in the design of energy-saving buildings

In this paper we describe the design and thermal behaviour of a bioclimatic Auditorium at the National University of La Pampa, used for teaching activities in Santa Rosa, La Pampa (Argentina). The building was monitored in winter and simulated with SIMEDIF for Windows, a code developed at the Non Conventional Energy Research Institute (INENCO, Argentina). Then, a new project of a similar building was proposed for General Pico city, and the obtained physical model was used to simulate the building under the summer temperatures of the new city. The building was redesigned and passive solar strategies were applied to reduce heating and cooling loads. The final layout and the monitored thermal behaviour of the new building in winter and summer are described. Without additional costc, the new building savings were 50% in heating requirements respect to the conventional layout, and 70% in the requirements of conventional energy for cooling.     

商住楼房沿街铺面的消防监督管理重点及对策

随着市场经济的繁荣发展,商住楼房沿街铺面的数量逐渐增多,满足了人们的多元化需求,加快了城市化建设进程.由于沿街铺面在空间布局、结构形式和经营性质等方面具有一定的特殊性,一旦发生火灾则会造成巨大损失,威胁人们的生命财产安全.因此,应该通过消防监督管理工作的实施,消除沿街铺面的火灾隐患,确保经营活动的顺利开展,保障社会和谐与稳定.本文将对商住楼房沿街铺面的火灾隐患进行分析,提出商住楼房沿街铺面火灾的主要原因,探索商住楼房沿街铺面的消防监督管理重点及对策.     

Energy performance of a cooling plant system using the inverter chiller for industrial building

The purpose of this paper is to clarify energy performance of the cooling plant system in the industrial building using actual measured operating data and numerical simulation analysis. One aspect of industrial buildings is that they have large energy consumption for manufacturing and air-conditioning compared with office and commercial buildings. Some examples of high-efficiency technologies installed in this particular cooling plant system are inverter chillers, integrated cooling towers and a free-cooling system. The inverter chiller which has been put on the market recently is state-of-the-art technology. The maximum COP of the inverter chiller reaches about 18 under certain conditions and integrated cooling towers make lower temperature cooling water as the whole capacity is large. Actual operating data indicates satisfied values for chiller and system COP during the running period and the simulation results show that the cooling plant system can cut down annual electric power consumption by about 48% compared with conventional cooling system.     

Strategic decision-making for intelligent buildings: Comparative impact of passive design strategies and active features in a hot climate

In the past years, there has been a growing interest among architects and entrepreneurs to include intelligence in buildings, as a way for achieving energy-efficient buildings that comply with stringent energy codes and national goals of reducing dangerous emissions, together with improving corporate image.