Energy performance criteria in the Hong Kong building environmental assessment method

The Hong Kong Building Environmental Assessment Method (HK-BEAM), an environmental assessment method for air-conditioned office buildings, has been developed by the Real Estate Developers Association (REDA) for use in Hong Kong. Two versions of the scheme have been developed; one for new office premises and the other for existing office premises. HK-BEAM embraces a variety of issues related to the global, local and indoor environments. The efficient use of electricity forms a major part of the assessment. The basis for the energy performance assessment method, and the criteria for obtaining the relevant credits are described and discussed.     

Benchmarking energy use assessment of HK-BEAM,BREEAM and LEED

The Hong Kong Building Environmental Assessment Method (HK-BEAM), Building Research Establishment Environmental Assessment Method (BREEAM) and LEED were formally launched in the 1990's. How well the certified and rated buildings compare with each other of an interest to building designers and policy makers. This paper describes how the baseline buildings, performance criteria and the credit scales of the three schemes compare with each other. By statistical analysis of the energy assessment results of 60 HK-BEAM certified buildings and the available data for BREEAM and LEED, it seeks to ascertained of buildings scoring excellent energy performance under different schemes belong to the top 5% in the market. Through this exercise, a systematic approach to benchmark the energy assessments across schemes has been established. With people nowadays paying greater attention to the environmental issues and the rapid development of the environmental schemes in various parts of the world, this study forms a good basis for future benchmarking of energy assessment schemes across nations.     

Benchmarking Hong Kong and China energy codes for residential buildings

Mandatory energy codes to curb energy use of residential buildings have been formally launched in China for more than two decades but little has been publicized in literature. Similar codes are not available for residential buildings in Hong Kong, but most residential buildings in Hong Kong, especially public housing estates, are HK-BEAM certified to demonstrate their compliance with regulatory and basic design requirements. Given HK-BEAM is internationally recognized and there are doubts about the effectiveness of the China codes, how the energy efficiency of the HK-BEAM certified buildings compare with buildings in compliance with the China codes is of interest to most building designers and policy makers. This paper describes how the energy efficiency of a case study building in compliance with the China codes compare with the one in compliance with HK-BEAM. The energy simulation by HTB2 and BECRES reveal that the case study building in compliance with the China codes is 51.1% better in energy use. In the study, the relative impact of each compliance criterion on energy use and cooling load has been quantified by sensitivity analysis. The sensitivity values indicate that energy use is most sensitive to air-conditioning operation hours, indoor design temperature, coefficient of performance (COP) of the room air-conditioners (RAC) units, and the envelop characteristics. The results of this study indicate that a HK-BEAM certified building cannot satisfy the China codes requirements. This provides good reference to the policy makers, the building owners, and to the China and Hong Kong Governments when considering reciprocal recognition of building energy codes.     

Energy performance assessment of existing dwellings

The existing buildings stock in European countries accounts for over 40% of final energy consumption in the European Union (EU) member states, of which residential use represents 63% of total energy consumption in the buildings sector. Consequently, an increase of building energy performance can constitute an important instrument in the efforts to alleviate the EU energy import dependency and comply with the Kyoto Protocol to reduce carbon dioxide emissions. This is also in accordance to the European Directive on the energy performance of buildings (EPBD), which has come to effect on 4 January 2006. The energy performance assessment for existing dwellings (EPA-ED) is a new methodology supported by software, developed in the framework of a European project that focuses on energy related issues for existing residential buildings, in line with the EPBD. This paper presents an overview of the method and software that can be used to perform building energy audits and assess buildings in a uniform way, perform demand and savings calculations, provide owners with specific advice for measures to improve energy performance, issue an energy performance certificate for existing buildings, and include some representative results from the pilot studies performed in several European countries. Also the sister-method EPA-NR, on non-residential buildings, currently under construction, is introduced.     

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.     

Using indicators to profile energy consumption and to inform energy policy in a university—A case study in Ireland

The services sector has the least amount of energy end use data available, which poses significant challenges to companies within the sector attempting to benchmark their energy performance and inform energy management decisions. This paper explores through a case study analysis the use of simple performance indicators and how additional data and new metrics can greatly enhance the understanding of energy trends and in particular the assessment of building energy performance. The country chosen for the analysis is Ireland, where the services sector has experienced high energy demand growth since 1990 (4.1% annually) compared with the EU-15 (1.5% annually). Despite this growth, the available energy data is poor, in particular for the public service sub-sectors. The case study chosen is an institution within the education sub-sector, University College Cork. The paper presents some simple energy performance indicators that have been used to date to inform energy policy. The paper then introduces new approaches and tools for assessing energy performance in buildings and how these may be utilised to improve the energy policy decision making and energy management. It discusses how these approaches are been implemented for buildings with separate functions, presents some initial results and discusses future planned work.     

Infrared thermovision technique for the assessment of thermal transmittance value of opaque building elements on site

Due to new regulations in the field of energy saving, international standards concerning energy requirements of buildings have been developed. In this field, during the design phase, one of the most important parameters to be considered is the value of heat losses coefficient through the envelope. Anyway, very often a great difference is experienced between predicted performance of building elements as calculated using the methods prescribed in technical standards, and the one considering as-build conditions, particularly in the field of building renovation where the envelope thermal transmittance value must be measured on site. Till now, the only method accepted by international standards is the heat flowmeter (HFM) that presents some restriction and some uncertainty in the results. In this study a faster and less invasive method is proposed, the infrared thermovision technique (ITT) whose full potentiality has never been investigated yet, in order to acquire quantitative data of real thermal transmittances of the building envelope in a quasi-steady state condition. The theoretic background is presented together with the application in three case studies. The results indicate that, following a specific methodology, it is possible to record significant data useful to perform a proper assessment of energy performance of existing buildings.     

Enhancing the sustainability and energy conservation in heritage buildings: The case of Nottingham Playhouse

Today, there is a growing interest in developing energy efficient buildings since it is estimated that buildings account for about 40% of the total primary energy consumption in the world. In relation to existing buildings, energy efficiency retrofits have become an important opportunity to upgrade the energy performance of commercial, public and residential buildings that may reduce the energy consumption, demand and cost. In this paper we cover the energy efficiency deep retrofit process that has been carried out for Nottingham Playhouse theatre building for the aim of enhancing its environmental performance and analysing the energy efficiency gained after implementing certain proposed modifications. It is a nationally protected historic building, listed as Grade II1 on The National Heritage List for England (NHLE). The building has had insulation enhancement, doors modifications, solar energy installations, energy-saving lights, in addition to improved heating and air conditioning system. The paper presents a novel methodology; and its results indicate significant improvements in the building's energy performance which is demonstrated using infrared thermographic images and data logger sensors where significant energy savings to the building's thermal performance are obtained. The energy saving measures have been completed while maintaining the heritage building's general appearance and architectural features, which have received a Commendation Certificate from The Nottingham Civic Society for this achievement.     

European residential buildings and empirical assessment of the Hellenic building stock,energy consumption,emissions and potential energy savings

The existing building stock in European countries accounts for over 40% of final energy consumption in the European Union (EU) member states, of which residential use represents 63% of total energy consumption in the buildings sector. Consequently, an increase of building energy performance can constitute an important instrument in the efforts to alleviate the EU energy import dependency (currently at about 48%) and comply with the Kyoto Protocol to reduce carbon dioxide emissions. This is also in accordance to the European Directive (EPBD 2002/91/EC) on the energy performance of buildings, which is currently under consideration in all EU member states. This paper presents an overview of the EU residential building stock and focuses on the Hellenic buildings. It elaborates the methodology used to determine the priorities for energy conservation measures (ECMs) in Hellenic residential buildings to reduce the environmental impact from CO₂ emissions, through the implementation of a realistic and effective national action plan. A major obstacle that had to overcome was the need to make suitable assumptions for missing detailed primary data. Accordingly, a qualitative and quantitative assessment of scattered national data resulted to a realistic assessment of the existing residential building stock and energy consumption. This is the first time that this kind of aggregate data is presented on a national level. Different energy conservation scenarios and their impact on the reduction of CO₂ emissions were evaluated. Accordingly, the most effective ECMs are the insulation of external walls (33–60% energy savings), weather proofing of openings (16–21%), the installation of double-glazed windows (14–20%), the regular maintenance of central heating boilers (10–12%), and the installation of solar collectors for sanitary hot water production (50–80%).     

城市规模的建筑能耗研究综述

城镇化速度的加快导致城市建筑能耗的快速增加,因此,城市规模的建筑能耗研究得到人们更多的关注。综述了国内外城市规模的建筑能耗研究现状。首先讨论城市建筑能耗分析与单体建筑能耗分析的差异,主要从4个方面论述,包括如何在城市环境中定义单体建筑、能耗数据获取、单体与群体建筑负荷差异、城市建筑之间的相互作用。然后将先前研究根据3个标准分类,分别是空间规模、建筑类型、能耗模型。综述表明,与城市规模的交通能耗研究相比,建筑能耗研究还处于非常初级的阶段,主要原因是缺少城市规模的群体建筑信息和能耗数据。同时,城市地理信息系统(GIS)的完善和新型统计学方法如贝叶斯和空间分析方法的出现,为城市规模建筑能耗的研究提供了新的机遇。     

上海地区办公建筑能耗的简化评价方法

针对既有办公建筑能耗评价方法,使用建筑“能效当量能耗”这一统计量来评价建筑能源使用情况,因为在“能效当量能耗”的计算过程中剔除了与能源使用效率无关因素的影响,评价结果更加客观.但既有方法需要获得详细的建筑信息,制约了其适用性.根据一定限制条件下既有方法的评价结果与应用单位面积能耗得到的评价结果之间的相似性,提出简化的能...     

A new methodology towards determining building performance under modified outdoor conditions

Great efforts have been made to establish the influence of the urban climate upon the energy consumption of buildings. While many scientific articles present measured data of increased energy consumption due to building surroundings, this paper aims to present a straightforward methodology for the assessment of building performance under modified outdoor conditions. Designers and urban planners should benefit from the results of this paper in their evaluation of proposals to decrease building energy consumption. A number of examples are discussed in order to illustrate the methodology outlined.     

A cost effective approach to design of energy efficient residential buildings

The objective of this study is to identify cost-optimal efficiency packages at several levels of building energy savings. A two-story residential building located in Jordan is selected as a case study. DesignBuilder software is used to predict the annual energy usage of a two-story residence in Irbid, Jordan. Real-time experimental data from a single isolated controlled room was used to verify the proposed model. In addition to energy analysis, the economic, environmental, and social benefits of the proposed design have been investigated. The sequential search optimization approach is used to estimate the minimum cost of the building while considering various design scenarios. In addition, the impact of various energy conservation techniques on residential buildings is assessed, and the payback period for each program is calculated. Ultimately, the optimal combination of design to achieve energy efficiency measures has been identified in several climate regions. The simulations results predict that the annual electricity consumption can be reduced up to 50% if the proper combinations of energy conservation measures are selected at the lowest cost. The payback period is 9.3 years. Finally, energy efficiency measures can lead to a total of 9470 jobs/year job opportunities.The study provide practical framework to link between energy performance criteria and economic goals of building. Linking the energy performance requirements to economic targets provides guidelines for homeowners, contractors, and policymakers for making a suitable decision regarding the retrofitting of existing residential buildings. The study focuses on developing new methodologies that support minimizing costs during a building's lifecycle while maximizing environmental benefits which can not be identified by a series of parametric analyses using individual energy-efficient measures.     

A review of benchmarking, rating and labelling concepts within the framework of building energy certification schemes

Energy certification schemes for buildings emerged in the early 1990s as an essential method for improving energy efficiency, minimising energy consumption and enabling greater transparency with regards to the use of energy in buildings. However, from the beginning their definition and implementation process were diffuse and, occasionally, have confused building sector stakeholders. A multiplicity of terms and concepts such as energy performance, energy efficiency, energy ratings, benchmarking, labelling, etc., have emerged with sometimes overlapping meanings. This has frequently led to misleading interpretations by regulatory bodies, energy agencies and final consumers.This paper analyses the origin and the historic development of energy certification schemes in buildings along with the definition and scope of a building energy certificate and critical aspects of its implementation. Concepts such as benchmarking tools, energy ratings and energy labelling are clarified within the wider topic of certification schemes. Finally, a seven steps process is proposed as a guide for implementing building energy certification.     

The use of normative energy calculation beyond building performance rating

Standardized building performance assessment is best expressed with a so-called normative calculation method, such as defined in the Committee for Standardization/International Organization for Standardization (CEN/ISO) calculation standards. The normative calculation method has advantages of simplicity, transparency, robustness and reproducibility. For systematic energy performance assessment at various scales, i.e. at the unit of analysis of one building up to a large-scale collection of buildings, the authors' group developed the Energy Performance Standard Calculation Toolkit (EPSCT). This toolkit calculates objective indicators of energy performance using either the monthly or hourly calculation method as specified in the CEN/ISO standard for building energy calculation. The toolkit is the foundation for numerous single, medium-scale and large-scale building energy management applications. At the largest level, applications should be able to manage hundreds or thousands of buildings. The paper introduces two novel applications that have the normative calculation at their core: (1) network energy performance modelling and (2) agent-based building stock energy modelling.     

Establishing target-oriented energy consumption quotas for buildings

The energy assessment of public buildings is currently emerging as an imperative of the Chinese government. However, in setting the overall control targets for entire regions, effective and specific energy consumption quotas (ECQs) for individual buildings are not specified. In this paper, in an effort to meet the energy conservation targets of the 12th Five-Year Plan, new methods for establishing target-oriented and equitable ECQs are proposed and applied in the assessment of a particular group of government office buildings in Beijing. The respective annual ECQs for electricity and gas were established for each building, and a corresponding year-end assessment was conducted. The core concept of the methods could be applied to other types of buildings and this concept could therefore provide important guidance for future policymaking.     

An object-oriented energy benchmark for the evaluation of the office building stock

Energy benchmarking is useful for understanding and enhancing building performance. The aim of this research is to develop an object-oriented energy benchmarking method for the evaluation of energy performance in buildings. Statistical analysis of the four-year monitored energy consumption data for office buildings was conducted. The results show that the energy use intensity follows the lognormal distribution with the Shapiro–Wilk normality test. Based on the lognormal distribution, the energy rating system for office buildings has been established. An object-oriented energy use intensity quota determination model has been developed. This research provides practical tools that enable decision-makers to evaluate a building's energy performance and determine the energy benchmark.     

Using intelligent clustering techniques to classify the energy performance of school buildings

The present paper deals with the energy performance, energy classification and rating and the global environmental quality of school buildings. A new energy classification technique based on intelligent clustering methodologies is proposed. Energy rating of school buildings provides specific information on their energy consumption and efficiency relative to the other buildings of similar nature and permits a better planning of interventions to improve its energy performance. The overall work reported in the present paper, is carried out in three phases. During the first phase energy consumption data have been collected through energy surveys performed in 320 schools in Greece. In the second phase an innovative energy rating scheme based on fuzzy clustering techniques has been developed, while in the third phase, 10 schools have been selected and detailed measurements of their energy efficiency and performance as well as of the global environmental quality have been performed using a specific experimental protocol. The proposed energy rating method has been applied while the main environmental and energy problems have been identified. The potential for energy and environmental improvements has been assessed.     

Green roofs; building energy savings and the potential for retrofit

Green roofs are a passive cooling technique that stop incoming solar radiation from reaching the building structure below. Many studies have been conducted over the past 10 years to consider the potential building energy benefits of green roofs and shown that they can offer benefits in winter heating reduction as well as summer cooling.This paper reviews the current literature and highlights the situations in which the greatest building energy savings can be made. Older buildings with poor existing insulation are deemed to benefit most from a green roof as current building regulations require such high levels of insulation that green roofs are seen to hardly affect annual building energy consumption.As over half of the existing UK building stock was built before any roof insulation was required, it is older buildings that will benefit most from green roofs. The case for retrofitting existing buildings is therefore reviewed and it is found there is strong potential for green roof retrofit in the UK.