A case study for the evaluation of realistic energy retrofit strategies for public office buildings in the Southern Hemisphere

The building sector offers significant opportunities for reducing the energy consumption with considerable economic, environmental and health benefits. Governments can lead the way by retrofitting existing public buildings to reinforce their commitment to improve energy efficiency. Similar design standards, end-uses and operational profiles are usually established for public buildings based on the services they offer. Retrofitting a public building can therefore serve as an ideal test-bed for energy efficiency measures for other buildings within a particular service category. This study first analysed the current electricity consumption of a public office building in Mauritius, located in the Southern Hemisphere. A complete model of the building was created, validated and then simulated to investigate the impact of realistic retrofit strategies on the electricity consumption. Results showed that lighting retrofit achieved the most significant reduction while measures that improved the thermal envelope of the building resulted in smaller energy savings. The possibility of exploiting solar energy was explored by simulating a 70 kW_p photovoltaic system installed on the roof. An equivalent of 8.5% of the annual electricity consumption of the building could thus be generated. A financial analysis is also presented for all retrofit scenarios in terms of annual return and payback period.     

Policy options towards an energy efficient residential building stock in the EU-27

The EU-27 residential building stock offers high potential for energy efficiency gains. The policies already in place or proposed to improve the energy efficiency and thus the environmental performance focus on new buildings and major renovations of existing buildings. However, there might be additional measures that could lead to further energy efficiency improvements. In particular, the installation of roofs or windows that show a high thermal efficiency outside major renovations offer a large improvement potential. In this study, the potential environmental and economic impacts of two types of such policy options were analysed: first, measures that require high energy efficiency standards when roofs or windows have to be replaced; and, second, measures that accelerate the replacement of building elements. The results suggest that the two policies offer the potential for substantial additional energy savings. In addition, the installation of energy efficient building elements comes at negative net cost. When the replacement of building elements is accelerated, however, the additional costs do not outweigh the energy cost savings.     

福建省夏热冬暖地区居住建筑节能率目标的研究与实施建议

作为福建省居住建筑设计强制性标准的核心内容,节能率目标的确定关系重大。本文采用常见的建筑节能计算软件,对福建省夏热冬暖地区南、北区建筑实现60%节能率所对应的围护结构性能指标进行计算,并结合工程实际、成本和经济社会效益等方面进行可行性分析,提出合理的节能率要求及实施方法。     

Optimum, technical and energy efficiency design of residential building in Mediterranean region

Jordan heavily relies on imported oil and gas for meeting its energy need as the same time the construction sector consumed more than half of the total electricity consumption in Jordan in 2008. In order to provide the occupants with thermal comfort at least cost, applying energy saving measures into early design stage can be significant to achieve this goal.This paper discusses an assessment of best orientation of the building, windows size, thermal insulation thickness from energetic, economic and environmental point of view for typical residential building located in Mediterranean region. The results show that about 27.59% of annual energy consumption can be saved by choosing best orientation, optimum size of windows and shading device, and optimum insulation thickness. The Life Cycle Cost (LCC) is reduced by 11.94%. The specific energy consumption per square meter is 64 kWh/m² a.     

Automatic generation of energy conservation measures in buildings using genetic algorithms

Building energy simulations are key to studying energy efficiency in buildings. The state-of-the art building energy simulation tools requires a high level of multi disciplinary domain expertise from the user and many technical data inputs that curb the usability of such programs. In this paper an IT tool is presented, which has the capability of predicting a building's energy utilization configuration based on the reported annual energy and a few non-technical inputs from the user; and correspondingly generates cost effective energy conservation measures for the intended savings.The approach first identifies the system variables that are critical to a building's energy consumption and searches for the combination of these parameters that would give rise to the annual energy consumption as reported by the facility. Genetic algorithms are utilized to generate this database. A statistical fit is formulated between the system variables and the annual energy consumption from the database. Using this correlation, system configuration for the target energy efficiency is determined with corresponding energy conservation measures. A cost analysis is carried out to prescribe the most cost effective energy conservation measures. Competency of the tool is demonstrated in the paper through case studies on three geographies with different climate conditions.     

Elaboration of energy saving renovation measures for urban existing residential buildings in north China based on simulation and site investigations

It is necessary to determine whether to implement a retrofit measure or not based on its energy saving and economic benefits, when conducting a retrofit project. The common way to do that is to set up a building simulation model and calculate its energy saving and economic benefits. Because of the great discrepancy between the actuality and the building simulation model, it is very important to use the factual energy use to calibrate the model, so as to accurately predict the benefits of retrofit measures. Although the energy efficiency retrofit of residential buildings in north China is implemented in a large scale, it seldom knows whether the commonly used retrofit packages are optimized. Therefore, a typical residential building is selected in Beijing, and the energy saving and economic benefits of different retrofit measures are analyzed using a simulation model calibrated with its actual space heating energy use, and the optimized retrofit packages are put forward. Results shows the retrofit of space heating system is a very attractive measure due to its relatively low investment but good energy saving benefit, and roof retrofit is also cost effective, while window retrofit and wall retrofit are not economic to conduct separately. Four optimized retrofit packages are figured out to realize the 50% and 65% reductions of space heating intensity required in the energy efficiency standards, which have less investment costs compared with currently widely used packages, and the retrofit packages for the 65% reduction is more cost-effective than the packages for the 50% reduction.     

Optimum insulation thicknesses for building walls with respect to cooling and heating degree-hours in the warmest zone of Turkey

Thermal insulation is one of the most effective energy conservation measures for cooling and heating in buildings. Therefore, determining and selecting the optimum thickness of insulation is the main subject of many engineering investigations. In this study, the determination of optimum insulation thickness on external walls of buildings is comparatively analyzed based on annual heating and cooling loads. The transmission loads, calculated by using measured long-term meteorological data for selected cities, are fed into an economic model (P₁−P₂ method) in order to determine the optimum insulation thickness. The degree-hours method that is the simplest and most intuitive way of estimating the annual energy consumption of a building is used in this study. The results show that the use of insulation in building walls with respect to cooling degree-hours is more significant for energy savings compared to heating degree-hours in Turkey's warmest zone. The optimum insulation thickness varies between 3.2 and 3.8 cm; the energy savings varies between 8.47 and 12.19 $/m²; and the payback period varies between 3.39 and 3.81 years depending on the cooling degree-hours. On the other hand, for heating load, insulation thickness varies between 1.6 and 2.7 cm, energy savings varies between 2.2 and 6.6 $/m², and payback periods vary between 4.15 and 5.47 years.     

Building typologies as a tool for assessing the energy performance of residential buildings - A case study for the Hellenic building stock

Successful strategies towards minimizing the energy consumption and greenhouse gas emissions attributed to the building sector require knowledge on the energy-related characteristics of the existing building stock. Despite the numerous studies on energy conservation applications in buildings, current knowledge on the energy-related characteristics of the building stock still remains limited. Building typologies can be a useful instrument to facilitate the energy performance assessment of a building stock. This work is based on a harmonised structure for European building typologies (TABULA) developed for residential buildings, but the methodology may be extended to the tertiary sector as well. National typologies are sets of model buildings with characteristic energy-related properties representative of a country's building stock. The model buildings are used as a showcase for demonstrating the energy performance and the potential energy savings from typical and advanced energy conservation measures (ECMs) on the thermal envelope and the heat supply system. The proposed Hellenic residential building typology is presented for the first time along with an assessment of various ECMs that are used for an estimate of the energy performance of building stock in Greece in an effort to meet the 9% indicative national energy savings target by 2016.     

A methodology for energy-efficient renovation of existing residential buildings in China and case study

Energy-efficient renovation had been accepted widely as the best solution for aging residential buildings. In order to guide such real projects in China and maximize the benefits in energy, environmental and economic fields from these activities, this article developed a methodology to assist decision-makers to design energy-efficient renovation plan in the early stage of design phase, and used a case study to demonstrate how to apply it. Following it, a suitable energy-efficient renovation plan, integrating all effective and available energy-saving measures, could be put forward for the subject building, and its effects on reduction of energy consumption, CO₂ emission and cost be evaluated accurately. The results showed that from the viewpoint of reducing energy consumption and CO₂ emission, energy-efficient renovation was worth being implemented to upgrade the existing residential buildings in China, but from the economic view, governments should provide certain subsidy for such real projects and increase electricity price.     

计算机模拟在建筑节能设计中的应用

依据DBJ13—62—2004《福建省居住建筑节能设计标准实施细则》,从节能率、成本、建筑热舒适性、节能方案适宜性等方面对比分析了规定性指标节能设计法与动态权衡计算设计法的优劣。得出计算机仿真模拟技术在建筑节能设计中应用的重要性。     

基于BIM的小型节能建筑生命周期环境影响和成本分析

被动式超低能耗建筑通过被动式设计策略、高性能的围护结构和高效的设备体系降低其使用阶段能耗。零能耗建筑在此基础上,采用太阳能光伏发电等可再生能源系统,进一步降低不可再生能源消耗。这两类节能建筑的材料和设备系统的隐含能耗、环境影响和成本通常高于一般建筑,同时对构件的后期维护和替换提出了更高的要求。因此,有必要从生命周期的范畴分析其环境和经济效益。建筑信息模型（BIM）能够为建筑项目的建造、运行和拆解等阶段提供多专业共享的数据平台。本文基于BIM,通过LCA和LCC方法对一座小型住宅建筑在不同节能目标情景下的生命周期全球变暖潜势值（GWP）、一次能耗（PE）和成本（LCC）进行分析和比较。结果表明,零能耗乃至正能源建筑在降低一次能耗和GWP方面具有明显优势,被动式超低能耗建筑也具有良好的环境效益。在经济效益方面,由于住宅建筑能源价格较低,如果按近年的价格指数计算,零能耗建筑和被动式超低能耗建筑的初建成本和后期构件替换成本增量将抵消其使用阶段节约的能耗成本,因此生命周期成本高于普通节能建筑。如果未来50年能源价格涨幅超过建筑安装价格涨幅,那么零能耗建筑在生命周期成本方面将具有优势。     

Optimisation of opaque components of the building envelope. Energy,economic and environmental issues

The European Directive 2002/91 will enforce the Member State to promote the implementation of new measures, instruments and calculation methodology to improve the buildings energy performances. The thermal performance and quality of the Italian residential buildings is generally poor, depending on the age of the building stock and the lack of application of the existing energy regulations. This study aims at demonstrating the global benefits of good insulated building envelopes. Energy benefits are easy to understand, meanwhile the economic issues are critical, since the final users see them as an additional useless extra cost for the dwelling at the purchase phase, with small attention to the future managing costs. The study demonstrates that significant economic advantages come out from high–performance building envelope. The study also shows that environmental extra loads due to a bigger use of the insulating material is paid back in few years, with consistent social benefits, if the life cycle of the building is taken into account.     

Energy efficiency and economic feasibility analysis of cogeneration system driven by gas engine

A cogeneration system driven by gas engine is proposed and studied. The cogeneration system can provide electricity generation and cooling/heating for buildings. The cogeneration system has a large potential for energy saving and economical benefits. Primary energy rate (PER) and comparative primary energy saving are used to evaluate and compare the performances of the cogeneration system and conventional separate system. The comparative primary energy saving of the cogeneration system is more than 37% compared to conventional separate system at the required energy flows. The total annual income, the total annual saving and payback period of the cogeneration system are used to analyze its economy. The calculation result of economic analysis shows that the cogeneration system has a good economic benefits.     

Investigation on energy performance and energy payback period of application of balcony for residential apartment in Hong Kong

The provision of balcony to the living room of a residential flat offers a number of merits including improved view enjoyment, enhanced ventilation and increased planting space. In addition, a balcony can act as an overhang and provide solar shading as well as electricity saving of the air-conditioning system. This paper reports the findings on the energy and environmental impact due to the provision of a balcony. In this study, a typical residential flat with balcony constructed at the living room was modeled and the energy performance was investigated with the use of the typical weather data set of a subtropical city, Hong Kong. The effects of balcony's orientation and glazing material of window were also evaluated. It was found that the residential flats facing various orientations (N, E, S, W, NE, SE, SW and NW) can offer substantial energy saving in air-conditioning system due to the shading effect of balcony. The building case with southwest facing balcony and clear glass glazed window gave the highest saving percentage of 12.3% in annual air-conditioning consumption. In terms of cost payback period, the values were estimated as 25.9 years (based on extra construction cost of a balcony) and over 100 years (based on extra purchasing cost), respectively. On the other hand, the energy payback period was 22.4 years for this building case. The provision of balcony to the living room of residential flat was found environmentally feasible in Hong Kong.     

夏热冬暖南区居住建筑节能的设计优化——以泉州市“见龙亭”小区项目为例

文章通过对"见龙亭"小区工程案例介绍,论述了处于夏热冬暖南区的居住建筑节能设计中采用性能性指标设计对居住建筑节能优化的技术应用和现实意义,该优化设计方法对较大区域和居住小区建筑节能具有明显的社会经济效益。     

西安地区既有居住建筑节能改造初探

针对西安地区既有居住建筑能耗大的问题,本文通过论述既有居住建筑改造现状和能耗现状,并对其能耗进行分析,指出西安地区既有居住建筑节能改造的重点在于围护结构的改造和周边环境的改进。同时,提出了相关的节能改造措施,希望能为西安地区既有居住建筑节能改造提供参考。     

呼和浩特市既有住宅热环境与节能改造分析

以呼和浩特市城区老旧多层住宅建筑为研究对象,采用以EnergyPlus为计算核心的DesignBuilder软件对其在原有情况下的室内温度、热舒适度以及建筑能耗进行分析,并对不同房间、不同楼层的室内热环境进行分析。根据内蒙古地区最新居住建筑节能设计标准对研究对象进行不同部分围护结构改造。以原有建筑能耗做对比,分析不同改造措施的节能效率。分析在采用节能改造措施后的住宅室内的温度、热舒适度及能耗的改善情况,提出呼和浩特市乃至内蒙古地区老旧多层住宅的热环境及节能改造措施。     

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.     

PKPM软件在建筑能效测评中的应用

以安徽省合肥市某居住建筑为例,介绍了PKPM软件在建筑能效测评中的应用。描述了该建筑在PKPM软件环境下的建模过程,并通过PKPM软件对该建筑的全年能耗进行了模拟,计算了其相对节能率。计算结果表明,该建筑的相对节能率达6.29%,符合安徽省对居住建筑的节能要求。     

利用建筑能效测评技术对建筑节能改造的研究

2008年江苏省建设厅颁布了《江苏省建筑节能管理办法》,专门增设了省级节能减排(建筑节能)专项引导资金,用于实施大型公共建筑和居住建筑既有建筑节能改造、建筑节能成熟适用技术推广等建筑节能重点工程领域。镇江扬中市西来桥镇幸福花苑一期始建于20世纪80年代,没有按照节能设计标准建造,选取具有代表性的32#楼进行建筑能效测评与节能改造研究,对推动江苏省居住建筑节能改造具有十分重要的意义。