On the use of an energy certification database to create indicators for energy planning purposes: Application in northern Italy

Energy certification of buildings, mandatory under the European Directive EPBD provides interesting data on the thermo-physical properties and geometry of existing buildings. Although the energy certificate is intended to provide the characteristics of individual buildings, so stimulating the real estate market toward ever better energy performance, data management of the certificates issued over time, using a national or regional energy cadastre, makes available a data base which is useful for energy planning in the building sector.This paper provides the needed results of a benchmarking study on data from the energy cadastre of the Lombardy Region, northern Italy. By integrating data from the energy cadastre (175.778 energy certificates) with the statistical data obtained from the national census, indicators were obtained on the energy performance of existing buildings.The energy indicators obtained, characterised by building type and construction period, normalised as a function of Degree-Days, become an effective tool for energy planning at local and regional scales. In the specific case, the energy indicators have been used to estimate the potential for energy retrofit of existing buildings in the Lombardy Region. The same indicators can also be used by municipalities for energy planning at the municipal or district level.     

Development of a methodology for life cycle building energy ratings

Traditionally the majority of building energy use has been linked to its operation (heating, cooling, lighting, etc.), and much attention has been directed to reduce this energy use through technical innovation, regulatory control and assessed through a wide range of rating methods. However buildings generally employ an increasing amount of materials and systems to reduce the energy use in operation, and energy embodied in these can constitute an important part of the building's life cycle energy use. For buildings with ‘zero-energy’ use in operation the embodied energy is indeed the only life cycle energy use. This is not addressed by current building energy assessment and rating methods.     

Energy performance of an exhibition hall in a life cycle perspective: embodied energy,operational energy and retrofit strategies

Nowadays, the focus on the building energy consumption in the use phase prevails over an interest concerning the energy impacts linked to all the other phases of the construction process. However, reducing operational energy could lead to shifting the impacts from one stage to another. Thus, combining the study of strategies improving energy efficiency in the use phase with a life cycle approach is crucial. Exhibition halls are peculiar buildings from the geometry, construction and use points of view, rarely addressed in energy and life cycle energy analysis studies. Therefore, in this paper, a representative hall of the Milan Trade Fair is taken as a case study. A building energy simulation model is firstly calibrated in order to derive the operational energy for climatisation. The operational energy appears artificially low due to the short use period during the year. When compared with the calculated embodied energy of the envelope and structure, it is found that 57 years would be needed to balance energy spent in the construction and in the use phase. Further, some retrofit interventions are proposed and analyzed. Insulation interventions are not attractive from the economic payback time point of view. However, when the embodied energy of the retrofit interventions is compared with the energy savings in the use phase, interesting energy payback times are obtained. Therefore, this study puts in evidence on the importance of adopting a life cycle perspective, especially for buildings with low-intensity use. Eventually, the critical issues of the life cycle energy analysis are deeply discussed.     

The potential for large-scale savings from insulating residential buildings in the EU

Energy used in buildings is responsible for more than 40% of energy consumption and greenhouse gas (GHG) emissions of the EU and their share in cost-efficient GHG mitigation potentials is estimated to be even higher. In spite of its huge savings potential of up to 80%, achievements are very slow in the building sector and much stronger political action seems to be needed. One important step in this direction has been the recast of the Energy Performance of Buildings Directive (EPBD) in autumn 2009. However, strong national implementation including powerful packages of flanking measures seems to be crucial to really make significant progress in this important field. In order to directly improve political action, we provide a differentiated country-by-country bottom up simulation of residential buildings for the whole EU, Norway, Iceland, Croatia and Liechtenstein. The analysis provides a database of the building stock by construction periods, building types, as well as typical building sizes. It includes a simulation of the thermal quality and costs of the components of the building shell for new buildings as well as the refurbishment of the existing building stock. Based on this differentiated analysis, we show in detail what would be needed to accelerate energy savings in the building sector and provide a more precise estimate of the potentials to be targeted by particular policies. We demonstrate, e.g. that the potential of building codes set via the EPBD would be located mainly in those countries that already have quite stringent codes in place. We show as well the high relevance of accelerating refurbishments and re-investment cycles of buildings. By providing a clear estimate of the full costs related to such a strategy, we highlight a major obstacle to accelerated energy-efficient building renovation and construction.     

Analysis of embodied energy use in the residential building of Hong Kong

Energy use in buildings accounts for nearly half of the total primary energy use in Hong Kong. Until now, studies have primarily focused on energy conservation in building operation, even though recent research has indicated that the embodied energy used in residential buildings could account for up to 40% of the life-cycle energy used in residential buildings. Accordingly, this paper presents a study on the energy embodied in the residential building envelope of Hong Kong. A model for estimating the intensities of the embodied and demolition energy for buildings has been developed. Two typical high-rise residential buildings, the Housing Authority Harmony 1 and the New Cruciform blocks, are analysed based on the developed model. The results of the analysis provide an insight into the embodied energy usage profile in residential buildings in Hong Kong. Energy embodied in steel and aluminium ranks as the first and second largest energy demand and may account for more than three-quarters of the total embodied energy use in a residential building envelope in Hong Kong. This reveals those building components with significant potential for reduction in embodied energy demand.     

A case study for influence of building thermal insulation on cooling load and air-conditioning system in the hot and humid regions

Ensuring the effective thermal insulation in regions, where the cooling requirement of building with respect to heating requirement is dominant, is very important from the aspect of energy economy. In this study, the influence of thermal insulation on the building cooling load and the cooling system in case of air-conditioning by an all-air central air-conditioning system was evaluated for a sample building located in Adana, based on the results of three different types of insulation (A, B and C-type buildings) according to the energy efficiency index defined in the Thermal Insulation Regulation used in Turkey. The operating costs of the air-conditioning system were calculated using cooling bin numbers. Life-cycle cost analysis was carried out utilizing the present-worth cost method. Results showed that both the initial and the operating costs of the air-conditioning system were reduced considerably for all three insulation thicknesses. However, the optimum results in view of economic measurements were obtained for a C-type building. The thickness of thermal insulation for the buildings in the southern Turkey should be determined according to the guidelines for a C-type building.     

Potential impact evaluation: an ex ante evaluation of the Mediterranean buildings energy efficiency strategy

The building sector is among the largest energy users while offering cost-effective means of reducing energy use. Dynamics of energy efficiency improvements in the building stock are very slow due to the long life span of buildings and barriers such as high investment cost. A list of general policy measures to overcome the barriers to energy efficiency improvements in the Mediterranean (MED) area was proposed by regional experts in the framework of the MARIE project. These measures could be considered as a first draft of the MED buildings energy efficiency strategy. This study assesses the potential impacts of such measures, so as to inform on their effectiveness. The MARIE measures result in larger energy savings than an equally ambitious strategy based on ‘conventional measures’. However, the benefits of MARIE arrive slowly and show large variations among regions depending on the characteristics of their current building stock.     

Success factors of energy performance contracting (EPC) for sustainable building energy efficiency retrofit (BEER) of hotel buildings in China

Hotel building is a type of high-energy-consuming building and most existing hotel buildings need energy efficiency improvement in China. Energy performance contracting (EPC) is considered a win−win mechanism to organize building energy efficiency retrofit (BEER) project. However, EPC mechanism has been introduced into China relatively recently and many EPCs have not been successful in building energy efficiency retrofit projects. This research aims to develop a set of critical success factors (CSFs) of EPC for sustainable energy efficiency retrofit (BEER) of hotel buildings in China. Semi-structured interviews and a questionnaire survey with practitioners and other professionals were conducted. The findings reveal the relative importance of the 21 number of identified success factors. In order to explore the underlying relationship among the identified critical success factors (CSFs), factor analysis method was adopted for further investigation, which leads to grouping the 21 identified CSFs into six clusters. These are (1) project organization process, (2) EPC project financing for hotel retrofit, (3) knowledge and innovation of EPC, sustainable development (SD), and M&V, (4) implementation of sustainable development strategy, (5) contractual arrangement, and (6) external economic environment. Finally, several relevant policies were proposed to implement EPC successfully in sustainable BEER in hotel buildings.     

建筑系统节能初探

本文在建筑节能中引入了系统和载能体的概念,提出了建筑系统节能的思想,分析了研究建筑系统节能所涉及的时空范围及内容,把资源与能源在时空范围的输入与输出看作载能过程,通过载能流,简化了复杂的时空关系,基于此,用系统工程的研究方法,划分了建筑节能系统,探索了建模思路,提出建模方法,为优化建筑节能方案和对建筑系统能耗模拟分析软件开发又提供了新思路.     

In search of better energy performance in the Portuguese buildings—The case of the Portuguese regulation

The Energy Performance of Buildings Directive (EPBD) is an important European policy tool to improve energy performance of buildings and has been applied in 27 countries with specific adjustments.     

An energy benchmarking model based on artificial neural network method with a case example for tropical climates

Energy benchmarking is an important step in evaluating a buildings energy use and comparing it with similar buildings in similar climates. Depending on the benchmarking results, extra measures can be taken to reduce energy consumption when the subject building has been assessed to consume more than other similar buildings. This study presents the current state of energy benchmarking‐related research and available tools. An artificial neural networks (ANN)‐based benchmarking technique is presented as a highly effective method. The model specifically focuses on predicting a weighted energy use index (EUI) by taking into consideration various building variables, such as plug load density, lighting type and hours of operation, air conditioning equipment type and efficiency, etc. Data collected from laboratory, office and classroom‐type buildings and mixed use buildings in Hawaii are used to present the ANN‐based benchmarking technique. The developed model successfully predicted the benchmarking EUI for the buildings considered in the study. The model coefficient of correlation was 0.86 for the whole building benchmarking analysis, indicating a good correlation between the measured EUI and the ANN predictions. Additionally, the use of ANN benchmark model for predicting potential energy savings from retrofit projects was evaluated. Some of the benchmarking input variables were modified to reflect a potential energy savings from a retrofit project and the new input set was simulated with the ANN model. The preliminary results show that the developed ANN model can be used to predict energy savings from retrofit projects. Copyright © 2006 John Wiley & Sons, Ltd.     

Cost-optimal energy performance measures in a new daycare building in cold climate

New municipal service buildings must be energy effective, and cost-optimality is one of the criteria for selecting the suitable energy performance improvement measures. A daycare building in a cold climate was studied by means of simulation-based, multi-objective optimisation. Using a genetic algorithm, both target energy use and life-cycle cost of the selected measures were minimised. It was found that extensive insulation of the building envelope is not a cost-optimal method to reduce the daycare building energy use. Improving energy efficiency of the ventilation system, utilising solar energy on-site and employing a light control strategy are preferable ways of improving the building energy performance. Ground-source heat pump is a more cost-optimal heating system for the daycare building than district heating. The cost-optimal sizing of the heat pump is small, only 28% of the required maximum heating power.

Abbreviations: AHU: air handling unit; CAV: constant air volume; COMBI: comprehensive development of nearly zero-energy municipal service buildings; COP: coefficient of performance; DH: district heating; DHW: domestic hot water; EPBD: energy performance of buildings directive; EU: European Union; FINVAC: Finnish Association of HVAC Societies; GSHP: ground-source heat pump; HRU: heat recovery unit; IDA ICE: IDA Indoor Climate and Energy; LED: light-emitting diode; MOBO: multi-objective building optimisation tool; NSGA-II: Non-dominated Sorting Genetic Algorithm II; nZEB: nearly zero-energy building; PV: photovoltaic; TRY: test reference year; VAV: variable air volume; ZEB: zero-energy building     

Stochastic assessment of the energy performance of buildings

A building’s energy performance is a complex multi-dimensional metric consisting of a variety of parameters. Presented herein are the results of a stochastic analysis of the factors affecting a building’s energy performance. The analysis is based on the Dwelling Energy Assessment Procedure (DEAP) (amended for cooling loads) and the general guidelines prescribed by the European Energy Performance of Buildings (EPBD) Directive 2010/31/EU. Modifications to the DEAP model are made for investigating the effect of variable external weather conditions on a building’s energy performance, and to incorporate the additional energy requirement for cooling. Subsequently, a stochastic analysis for three dwelling types is performed to assess the impact of 68 factors on the energy performance of buildings, for 12 different regions in Europe. It is concluded that (1) the factors with the greatest impact on energy use are in descending order, the floor area, external weather conditions, dwelling’s envelope u value (roof, window, walls, and floors), the space heating system, ventilation, windows area and walls area; (2) the energy performance of a building follows a lognormal probability distribution function; (3) buildings in colder EU regions exhibit higher energy profiles and higher variability in their energy profiles than those in warmer regions.     

Retrofitting solutions for two different occupancy levels of educational buildings in tropics

Within the multi-functionality of educational buildings, the energy conservation potential can be very different. In addition, among different retrofitting solutions investigated involving interventions on the building envelope, ventilation strategies, artificial lighting systems as well as equipment upgrading, different saving potential would come from different aspects. The opportunities for energy saving potential from the overall point of view and from the detailed aspect view of different retrofitting solutions would be very useful and important for building renovation decision making. This study presents a detailed retrofitting study of two different educational buildings. One represents a building with average occupancy variation and containing mainly offices and labs. The other one represents a building with high occupancy variation and containing mainly lecture rooms and studios. This comparison of the results gives an idea of the different energy saving potential for different types of educational buildings. Principal component analysis is also adopted to investigate the detailed performance of one of the buildings which is influenced stronger by these retrofitting solutions.     

济南某酒店空调系统节能改造

对济南某星级酒店空调系统改造项目进行节能分析,探讨了对使用年限较长、建筑能耗较大的既有建筑空调系统进行节能改造的必要性。对该酒店空调系统设计的特点、设备配置以及装修配合等方面进行了分析,并就新旧空调方案进行了经济性比较,结果表明改造后空调系统具有较好的经济性和节能性,为同类型酒店的节能改造提供参考。     

建筑中的固化能耗

分析了建筑中能耗由运行能耗，固化能耗两部分组成；固化能耗的具体含义以及研究固化能耗的意义；提出固化能耗的测定的不准确性。这种不准确性来源于三个方面：1.固化能耗的隐蔽性；2．固化能耗测定的长期性；3．固化能耗的界定范围可变性。然而，固化能耗的量化并不要求得出“正确”或“准确”的数字，量化的意义在于通过不同材料固化能耗的比较给建筑师选择材料时提供一个科学化的依据。最后，提供了一些常用建材的固化能耗测定值，并提出降低建材固化能耗的策略方法。     

Embodied and operational energy of rural dwellings in India

On a global scale, buildings are responsible for significant energy consumption. While the energy intake of urban buildings has been studied well, there are barely any studies on rural dwellings. The current paper examines the embodied energy (EE), operational energy (OE) and life-cycle energy (LCE) of 27 rural dwellings spread across four climate zones of India. It is found that these rural dwellings use locally available least-processed natural materials with very low EE. However, with the advent of modern transportation, manufactured energy-intensive construction materials have reached rural areas. From the analysis it is seen that the EE ranges from 0.002 to 2.8?GJ/m², the annual OE from 0.006 to 0.053?GJ/m² and the LCE from 0.77 to 4.05?GJ/m² for the rural dwellings studied, with mass ranging from 1.13 to 3.6?t/m².     

Climate dependence of energy saving strategies in public buildings characterized by change of use: an original case study

In the perspective of reducing land occupation of built environments, the most efficient strategy is to increase the reuse of obsolete or abandoned constructions instead of designing new buildings. This is particularly true regarding public buildings, usually characterized by considerable dimensions. The paper is focused on this issue, particularly on its energy implications. It analyzes the headquarters of the “G. D’Annunzio” University in Pescara, Italy, initially designed for commercial use and later converted to a university building during its construction. The authors first carried out a numerical analysis of the building energy performance in its current state and then they proposed some improvement interventions evaluating their incidence on the annual energy balance of the building, showing how the most commonly used energy saving strategies do not give the best results in any case, being greatly influenced by the climatic zone in which the building is located. Starting from these considerations, the authors carried out the analysis by considering three different Italian climatic conditions so as to determine their influence on the building energy performance and to define the best strategy for energy requalification in each climatic zone.     

A review of occupant control on natural ventilation

According to IPCC (Intergovernmental Panel on Climate Change), the largest use of energy in commercial buildings is space heating in colder climates and air conditioning in hot climates. In Europe, the Directive on the energy performance of buildings EPBD (European Energy Performance of Buildings Directive) [1] provides a framework for national building performance regulations and calculation procedures. However, there are often large discrepancies between calculated and measured energy performance of buildings. One main reason is the behaviour of occupants, which is often not reflected in calculation models.This paper presents a literature review of various parameters influencing the effectiveness of occupant controlled natural ventilation. Additionally possibilities to implement these influences into calculation procedures/building simulation and adaptive thermal comfort evaluation are discussed.