Embodied emissions abatement—A policy assessment using stochastic analysis

Policymakers traditionally focus on regulating operational energy use in buildings, ignoring other life cycle components such as embodied energy even though this may account for a significant portion of life cycle emissions. Data relating to embodied energy and emissions in buildings is limited. However, stochastic techniques can be used to estimate the distribution of such emissions from buildings. This helps policymakers identify which instruments are appropriate for achieving emissions reductions. A primary aim of this paper is to demonstrate this approach using a sample of apartment buildings in Ireland. A Monte-Carlo simulation suggests that the average probability distribution of embodied greenhouse gases in a sample of Irish apartment buildings is characteristic of a Wakeby distribution with a long tail which can be targeted for improvement through the implementation of appropriate policies. Two policies are investigated: one regulatory whereby the embodied emissions of building materials are limited to the 80th percentile of their current distributions; and one informational where buildings are given an embodied emissions rating. It is estimated that such policies could result in an average reduction of 450 gCO₂-eq/€ for the sample of apartment buildings analysed and could result in savings of €2bn to EU-27 countries in avoided carbon credits.     

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.     

Need for an embodied energy measurement protocol for buildings: A review paper

Buildings consume a vast amount of energy during the life cycle stages of construction, use and demolition. Total life cycle energy use in a building consists of two components: embodied and operational energy. Embodied energy is expended in the processes of building material production, on-site delivery, construction, maintenance, renovation and final demolition. Operational energy is consumed in operating the buildings. Studies have revealed the growing significance of embodied energy inherent in buildings and have demonstrated its relationship to carbon emissions.Current interpretations of embodied energy are quite unclear and vary greatly, and embodied energy databases suffer from the problems of variation and incomparability. Parameters differ and cause significant variation in reported embodied energy figures. Studies either followed the international Life Cycle Assessment (LCA) standards or did not mention compliance with any standard. Literature states that the current LCA standards fail to provide complete guidance and do not address some important issues. It also recommends developing a set of standards to streamline the embodied energy calculation process.This paper discusses parameters causing problems in embodied energy data and identifies unresolved issues in current LCA standards. We also recommend an approach to derive guidelines that could be developed into a globally accepted protocol.     

Net energy analysis of domestic solar water heating installations in operation

The potential of solar water heating systems to reduce domestic energy use is frequently acknowledged. However there are two factors that are rarely discussed when studying this technology. Firstly the real performance of the installed systems in operation, and secondly a life cycle perspective of its energy use. These two issues are reviewed in this paper, and a field study in Ireland is also presented. In the review, some studies show that measured real performance of domestic solar water heating systems can be lower than expectations. Concerning their life cycle energy performance, existing studies show that the initial energy investment for the systems (their embodied energy) is a small portion of the energy savings over their lifetime with calculation paybacks generally lower than 2 years. On the field study carried in Ireland, representative of a maritime north European climate, the ‘energy payback’ based on the expected energy savings is between 1.2 and 3.5 years, values comparable to previous studies considering the less favourable climate and installation characteristics. However the measured energy savings generally worsened the life cycle energy performance of this technology and thus increased the energy payback period. The study concludes that while there is a real potential for life cycle energy savings through domestic solar water heating installations, devising mechanisms to ensure proper design, installation and operation of systems is essential for this technology.     

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.     

Assessment of CO2 emissions reduction in a distribution warehouse

Building energy use accounts for almost 50% of the total CO₂ emissions in the UK. Most of the research has focused on reducing the operational impact of buildings, however in recent years many studies have indicated the significance of embodied energy in different building types. This paper primarily focuses on illustrating the relative importance of operational and embodied energy in a flexible use light distribution warehouse. The building is chosen for the study as it is relatively easy to model and represents many distribution centres and industrial warehouses in Europe.A carbon footprinting study was carried out by conducting an inventory of the major installed materials with potentially significant carbon impact and material substitutions covering the building structure. Ecotect computer simulation program was used to determine the energy consumption for the 25 years design life of the building. This paper evaluates alternative design strategies for the envelope of the building and their effects on the whole life emissions by investigating both embodied and operational implications of changing the envelope characteristics. The results provide an insight to quantify the total amount of CO₂ emissions saved through design optimisation by modeling embodied and operational energy.     

A generalized window energy rating system for typical office buildings

Detailed computer simulation programs require lengthy inputs, and cannot directly provide an insight to relationship between the window energy performance and the key window design parameters. Hence, several window energy rating systems (WERS) for residential houses and small buildings have been developed in different countries. Many studies showed that utilization of daylight through elaborate design and operation of windows leads to significant energy savings in both cooling and lighting in office buildings. However, the current WERSs do not consider daylighting effect, while most of daylighting analyses do not take into account the influence of convective and infiltration heat gains. Therefore, a generalized WERS for typical office buildings has been presented, which takes all primary influence factors into account. The model includes embodied and operation energy uses and savings by a window to fully reflect interactions among the influence parameters. Reference locations selected for artificial lighting and glare control in the current common simulation practice may cause uncompromised conflicts, which could result in over- or under-estimated energy performance. Widely used computer programs, DOE2 and ADELINE, for hourly daylighting and cooling simulations have their own weaknesses, which may result in unrealistic or inaccurate results. An approach is also presented for taking the advantages of the both programs and avoiding their weaknesses. The model and approach have been applied to a typical office building of Hong Kong as an example to demonstrate how a WERS in a particular location can be established and how well the model can work. The energy effect of window properties, window-to-wall ratio (WWR), building orientation and lighting control strategies have been analyzed, and can be indicated by the localized WERS. An application example also demonstrates that the algebraic WERS derived from simulation results can be easily used for the optimal design of windows in buildings similar to the typical buildings.     

Beyond the EPBD: The low energy residential settlement Borgo Solare

The European Directive on Energy Performance of Buildings (EPBD) imposes the adoption of measures for improving the energy efficiency in buildings. These measures should take into account the local weather conditions as well as internal thermal environment and cost-effectiveness. In this respect, Italy is a very interesting benchmark. For Northern Italy, the climatic context is particularly difficult to deal with cold winters and hot summers. The legislations are changing very rapidly, but has not fully adapted to the local context. The considered methodology still involves winter heating while summer cooling is addressed in incomplete and inadequate ways. The energy issue is addressed only partially as final energy consumption, but with little attention to LCA. Moreover, the belief that the buildings with high energy savings are too expensive, and therefore not attractive from economic point of view. For these reasons, it is very important to develop case studies to demonstrate the effectiveness of sustainable energy in architecture, according to a holistic approach. This paper describes a detailed techno–economic analysis for Borgo Solare project, an extremely advanced and innovative residential settlement designed on sustainable architecture concepts. One of the most innovative aspects of the project is that it is not just an experimental operation but Borgo Solare is a real urban district, which will be built without public funds and should be inhabited by common people. Excellent energy performance, therefore, must be accompanied by affordable market prices. The energy and economical analysis is presented taking into account also the embodied energy of the building. The results on the performance of a sample building (case study) of this settlement are reported, according to different construction standards: prior to EPBD, present from the EPBD and more efficient developed specifically for the project. It has been shown that using the better design practices and technologies the higher initial embodied energy in a low energy building could quickly paid back during its life span. The economic analysis, in the same way, evidences that higher initial investment in case of energy efficient building could become economically convenient during the life span of the building. This kind of analysis is essential to determine the actual sustainability of a building.     

Life-cycle energy of residential buildings in China

In the context of rapid urbanization and new construction in rural China, residential building energy consumption has the potential to increase with the expected increase in demand. A process-based hybrid life-cycle assessment model is used to quantify the life-cycle energy use for both urban and rural residential buildings in China and determine the energy use characteristics of each life cycle phase. An input–output model for the pre-use phases is based on 2007 Chinese economic benchmark data. A process-based life-cycle assessment model for estimating the operation and demolition phases uses historical energy-intensity data. Results show that operation energy in both urban and rural residential buildings is dominant and varies from 75% to 86% of life cycle energy respectively. Gaps in living standards as well as differences in building structure and materials result in a life-cycle energy intensity of urban residential buildings that is 20% higher than that of rural residential buildings. The life-cycle energy of urban residential buildings is most sensitive to the reduction of operational energy intensity excluding heating energy which depends on both the occupants' energy-saving behavior as well as the performance of the building itself.     

Life cycle energy and greenhouse emissions analysis of wind turbines and the effect of size on energy yield

Wind turbines, used to generate renewable energy, are typically considered to take only a number of months to produce as much energy as is required in their manufacture and operation. With a life expectancy of upwards of 20 years, the energy produced by wind turbines over their life can be many times greater than that embodied in their production. Many previous life cycle energy studies of wind turbines are based on methods of assessment now known to be incomplete. These studies may underestimate the energy embodied in wind turbines by more than 50%, potentially overestimating the energy yield of those systems and possibly affecting the comparison of energy generation options. With the increasing trend towards larger scale wind turbines, comes a respective increase in the energy required for their manufacture. It is important to consider whether or not these increases in wind turbine size, and thus embodied energy, can be adequately justified by equivalent increases in the energy yield of such systems. This paper presents the results of a life cycle energy and greenhouse emissions analysis of two wind turbines and considers the effect of wind turbine size on energy yield. The issue of incompleteness associated with many past life cycle energy studies is also addressed. Energy yield ratios of 21 and 23 were found for a small and large scale wind turbine, respectively. The embodied energy component was found to be more significant than in previous studies, emphasised here due to the innovative use of a hybrid embodied energy analysis approach. The life cycle energy requirements were shown to be offset by the energy produced within the first 12 months of operation. The size of wind turbines appears to not be an important factor in optimising their life cycle energy performance.     

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.     

Solar Versus Green: The Analysis of a Norwegian Row House

There are, presently, two schools of thought when it comes to designing buildings that promote sustainable development. One school emphasizes materials use and “green” buildings, while the other emphasizes energy use and low energy/solar buildings. The promoters of “green” buildings often claim that the reduced energy use during operation of the low energy and solar buildings is counteracted by the increased embodied energy in these buildings. This paper describes the results of a study of embodied energy and energy use in operation during the lifetime in a wooden row house. The house, designed and built as a solar house with very low energy use during operation, is located in southern Norway. It features both passive and active solar measures. In the study, the built version is compared with four other versions: two versions where the house is designed according to the requirements of the new Norwegian Building Code, one version where the house is designed according to present standards in Norway, and one version where the house is designed according to the principles used by the architects presently building “green” buildings in Norway. The results, which are also compared with some results from German studies, show that solar buildings have a lower overall energy use, when both embodied energy and energy use during operation are taken into account. The results also show that there should be little difference between the approaches of the two schools of thought. The best buildings will generally be those that are both solar, low energy, and “green”.     

Analysis of energy saving optimization of campus buildings based on energy simulation

The energy consumption of campus buildings has specific characteristics, because of the concentrated distribution of people’s working time and locations that change in line with distinct seasonal features. The traditional energy system design and operation for campus buildings is only based on the constant room temperature, such as 25°C in summer and 18°C in winter in China, not taking into consideration the real heating or cooling load characteristics of campus buildings with different functions during the whole day and whole year, which usually results in a lot of energy waste. This paper proposes to set different set-point temperatures in different operation stages of public and residential campus buildings to reduce the heating and cooling design load for energy station and total campus energy consumption for annual operation. Taking a campus under construction in Tianjin, China as an example, two kinds of single building models were established as the typical public building and residential building models on the campus. Besides, the models were simulated at both set-point room temperature and constant room temperature respectively. The comparison of the simulation results showed that the single building energy saving method of the peak load clipping could be used for further analysis of the annual energy consumption of campus building groups. The results proved that the strategy of set-point temperature optimization could efficiently reduce the design load and energy consumption of campus building groups.     

Method for rating energy performance of public buildings

This paper discussed a comparative study of several state-of-art methods for determining building energy consumption benchmark. A new approach, which combined the idea of “building benchmark” and “operational benchmark” in its rating system, was proposed. A case study was conducted which applied the proposed approach to benchmarking an existing office building in Tianjin. Besides, the calculation of benchmarks of the reference building model and real building model using the rating method in eQUEST was also considered. Furthermore, the simulation results of the reference building model were taken as the baseline to divide real office buildings into different energy performance grades.     

Influence of infiltration on energy consumption of a winery building

With the wide use of light steel structure in industrial buildings, some problems such as air leakage, water dripping and condensation and so forth occur during the construction and operation phases. Through the onsite testing of a winery building in Huailai County, Hebei Province in China, the influence of infiltration on energy consumption in industrial buildings was studied. The pressurization test method and moisture condensation method were used to test the infiltration rates. The results show that the winery building is twice as leaky as normal Chinese buildings and five times as leaky as Canadian buildings. The energy use simulation demonstrates that the reduction of the infiltration rate of the exterior rooms to 1/3 and the interior rooms to 1/2 could help decrease a total energy consumption of approximately 20% and reduce a total energy cost of approximately $ 225000. Therefore, it has a great potential to reduce the energy consumption in this type of buildings. Enforcement of the appropriate design, construction and installation would play a significant role in improving the overall performance of the building.     

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。     

Prediction of thermal buffer zone effectiveness in real‐size buildings—An experimental and analytical study

Global warming is caused by greenhouse gas (GHG) emissions produced from the use of fossil fuel–based energy sources. Buildings consume about 30% to 35% of the global energy use, which makes buildings a major contributor to the global warming problem. A long‐term plan has been established at the Thermal Processing Laboratory (TPL) at McMaster University to investigate the use of various renewable energy–based technologies to achieve net‐zero energy buildings (NZEB) in Canada. This paper presents results of an investigation of the effectiveness of using a thermal buffer zone (TBZ) in real‐size buildings. A TBZ is a closed passage built around the building that allows air to passively redistribute heat energy from solar radiation received on the south side throughout the building. A TBZ offers an effective solution of the overheating problem usually experienced on the south side of the building, and at the same time, it helps in reducing the heating load of the north side of the building. An experimental setup employing TBZ in a lab‐scale model of a typical building floor has been built. An analytical model of the TBZ has been developed. The experimental data has been used to validate the developed analytical model, which then was used to predict the performance of the TBZ implemented in a real‐size building floor, considering four cases. Results of the first three case studies considering the use of TBZ in cold and hot climates, with and without thermal insulation, show that the predicted effectiveness of TBZ could reach 117% and 72.5% in the winter and summer, respectively. Results of the fourth case study considering the effect of integrating a fan with the TBZ show that a fan is beneficial up to a certain fan power, beyond which the use of the fan would not be feasible. Results presented herein confirm that the TBZ is an effective means of integrating solar energy into buildings, thereby reducing buildings' fossil fuel–based energy consumption.     

Review of groundwater cooling systems in London

The environmental impact of the UK building stock has increased the pressure on architects, engineers and building operators to reduce the use of air conditioning in favour of more passive cooling solutions. Good progress has been made in this direction but many passive solutions are limited to new-build projects. For existing buildings, and those for which mechanical air conditioning cannot be avoided, low energy cooling capability can be incorporated to improve significantly overall efficiency. This paper focuses on one such low energy capability – cooling using groundwater, which has gained popularity in recent years in the London area. Among the reasons for this are the excellent energy efficiency and the increasing viability of water extraction systems. The paper shows that groundwater cooling technology can be incorporated into newly-build and existing buildings to help reduce the environmental impact of the UK building stock.     

Innovation,low energy buildings and intermediaries in Europe: systematic case study review

As buildings throughout their life cycle account for circa 40% of total energy use in Europe, reducing energy use of the building stock is a key task. This task is, however, complicated by a range of factors, including slow renewal and renovation rates of buildings, multiple non-coordinated actors, conservative building practices and limited competence to innovate. Drawing from academic literature published during 2005–2015, this article carries out a systematic review of case studies on low energy innovations in the European residential building sector, analysing their drivers. Specific attention is paid to intermediary actors in facilitating innovation processes and creating new opportunities. The study finds that qualitative case study literature on low energy building innovation has been limited, particularly regarding the existing building stock. Environmental concerns, EU and national and local policies have been the key drivers; financial, knowledge and social sustainability and equity drivers have been of modest importance; while design, health and comfort and market drivers have played a minor role. Intermediary organisations and individuals have been important through five processes: (1) facilitating individual building projects, (2) creating niche markets, (3) implementing new practices in social housing stock, (4) supporting new business model creation and (5) facilitating building use post-construction. The intermediaries have included both public and private actors, while local authority agents have acted as intermediaries in several cases.     

Asset and operational benchmarking for office buildings in Greece

The aim of this paper is to compare the asset and operational rating of buildings by the creation of a thermal model in TRNSYS 16 in order to simulate the thermal behaviour of a multi-storey (seven floors) office building that belongs to BYTE Computer S.A. located in Athens, Greece. Then based on the validated building model, the generalisation of this method is investigated for the creation of a virtual database for office building energy benchmarking in Greece. The data collected for the case-study building are based on engineering plans and studies, on in-situ measurements and mainly on the building management system (BMS) already implemented in the building. The building is modelled in detail by splitting it into 45 thermal zones. The simulation results are compared with the measured values provided by the BMS for two periods (winter and summer). The processing of the results leads to conclusions regarding the reliability of the model, the accuracy of asset rating compared to operational rating, as well as its usefulness in evaluating building retrofitting scenarios and its application as a general energy audit model for office buildings in Greece.