Life cycle energy analysis of eight residential houses in Brisbane, Australia

Life cycle energy analysis (LCEA) of eight residential buildings in and around Brisbane, Queensland, Australia, is undertaken in this study. Energy used in all three phases of construction, operation and demolition are considered. It is found that the main contribution to the operational energy in residential buildings is from use of general appliance. The choice of building materials is shown to have significant effects on the embodied energy for the production, construction, maintenance and demolition phases. From this study, it is shown that the embodied energy may vary from 10% to 30%, while the operational energy may vary from 65% to 90%. The demolition energy generally accounts for less than 4% of life cycle energy.

Life-Cycle Energy Analysis of a Modular/Off-Site Building School

This paper is concerned with assessing the building’s the energy efficiency and qualities of a modular design for the education industry, in order assess the long economic benefits. The research includes a life-cycle energy and cost analysis of the school building design, predicting the impact on the operational cost of the building as a result of the addition of photovoltaic panels. The paper also includes a comparative study between the ECO Modular Solutions building, and a current standard prefabricated school building, quantifying the savings in CO2 emissions and savings in cost.

Life-cycle energy analysis of building integrated photovoltaic systems (BiPVs) with heat recovery unit

Building integrated photovoltaic (BiPV) systems generate electricity, but also heat, which is typically wasted and also reduces the efficiency of generation. A heat recovery unit can be combined with a BiPV system to take advantage of this waste heat, thus providing cogeneration. Two different photovoltaic (PV) cell types were combined with a heat recovery unit and analysed in terms of their life-cycle energy consumption to determine the energy payback period. A net energy analysis of these PV systems has previously been performed, but recent improvements in the data used for this study allow for a more comprehensive assessment of the combined energy used throughout the entire life-cycle of these systems to be performed. Energy payback periods between 4 and 16.5 years were found, depending on the BiPV system. The energy embodied in PV systems is significant, emphasised here due to the innovative use of national average input–output (I–O) data to fill gaps in traditional life-cycle inventories, i.e. hybrid analysis. These findings provide an insight into the net energy savings that are possible with a well-designed and managed BiPV system.

A comprehensive framework for assessing the life cycle energy of building construction assemblies

Environmental decision making during the building design process has typically focused on improvements to operational efficiencies. Improvements to thermal performance and efficiency of appliances and systems within buildings both aim to reduce resource consumption and environmental impacts associated with the operation of buildings. Significant reductions in building energy and water consumption are possible; however often the impacts occurring across the other stages of a building‘s life are not considered or are seen as insignificant in comparison.

Previous research shows that embodied impacts (raw material extraction, processing, manufacture, transportation and construction) can be as significant as those related to building operation. There is, however, limited consistent and comprehensive information available for building designers to make informed decisions in this area. Often the information that is available is from disparate sources, which makes comparison of alternative solutions unreliable and risky. lt is also important that decisions are made from a life cycle perspective, ensuring that strategies to reduce environmental impacts from one life cycle stage do not come at the expense of an increase in overall life cycle impacts

A consistent and comprehensive framework for assessing and specifying building assemblies for enhanced environmental outcomes does not currently exist. This paper presents the initial findings of a project that aims to establish a database of the life cycle energy requirements of a broad range of construction assemblies, based on a comprehensive assessment framework. Life cycle energy requirements have been calculated for eight standard residential construction assemblies integrating an innovative embodied energy assessment technique with thermal performance simulation modelling and ranked according to their performance.

Optimising the life cycle energy performance of residential buildings

A holistic approach to low-energy building design is essential to ensure that any efficiency improvement strategies provide a net energy benefit over the life of the building. Previous work by the authors has established a model for informing low-energy building design based on a comparison of the life cycle energy demand associated with a broad range of building assemblies. This model ranks assemblies based on their combined initial and recurrent embodied energy and operational energy demand. The current study applies this model to an actual residential building in order to demonstrate the application of the model for optimising a building’s life cycle energy performance. The aim of this study was to demonstrate how the availability of comparable energy performance information at the building design stage can be used to better optimise a building’s energy performance. The life cycle energy demand of the case study building, located in the temperate climate of Melbourne, Australia, was quantified using a comprehensive embodied energy assessment technique and TRNSYS thermal energy simulation software. The building was then modelled with variations to its external assemblies in an attempt to optimise its life cycle energy performance. The alternative assemblies chosen were those shown through the author’s previous modelling to result in the lowest life cycle energy demand for each building element. The best performing assemblies for each of the main external building elements were then combined into a best-case scenario to quantify the potential life cycle energy savings possible compared to the original building. The study showed that significant life cycle energy savings are possible through the modelling of individual building elements for the case study building. While these findings relate to a very specific case, this study demonstrates the application of a model for optimising building life cycle energy performance that may be applied more broadly during early-stage building design to optimise life cycle energy performance.

A comprehensive framework for assessing the life-cycle energy of building construction assemblies

Building environmental design typically focuses on improvements to operational efficiencies such as building thermal performance and system efficiency. Often the impacts occurring across the other stages of a building's life are not considered or are seen as insignificant in comparison. However, previous research shows that embodied impacts can be just as important. There is limited consistent and comprehensive information available for building designers to make informed decisions in this area. Often the information that is available is from disparate sources, which makes comparison of alternative solutions unreliable. It is also important to ensure that strategies to reduce environmental impacts from one life cycle stage do not come at the expense of an increase in overall life-cycle impacts. A consistent and comprehensive framework for assessing and specifying building assemblies for enhanced environmental outcomes does not currently exist. This article presents the initial findings of a project that aims to establish a database of life cycle energy requirements for a broad range of construction assemblies, based on a comprehensive assessment framework. Life cycle energy requirements have been calculated for eight residential construction assemblies integrating an innovative embodied energy assessment technique with thermal performance modelling and ranked according to their performance. © #2010 Earthscan ISSN: 0003-8628.

An early-stage design decision-support tool for selecting building assemblies to minimise a building's life cycle energy demand

The significant effects of the building industry on the natural environment are well documented and improving the environmental performance of buildings is an on-going challenge. This is particularly the case for projects with restrictive budgets and timelines and because many existing environmental assessment tools are designed to be used too late in the design process. The use of tools during the early design stages may assist in achieving greater improvements in a building’s environmental performance. However, user-friendly tools with the ability to comprehensively compare environmental information between various building assemblies and materials, which can be easily adopted during the early design stages of a project, are not readily available. This paper presents the progress to date in developing a tool which supports building designers in identifying and selecting preferred building assemblies with the aim of minimising a building’s life cycle energy demand. The tool is based on comprehensive energy performance data for a broad range of building assemblies across all Australian climate zones. Allowing for adjustments to a set of pre-defined and user-defined assemblies the designer is able to see how assemblies perform in relation to each other. This provides valuable information to support decision-making relating to minimising the life cycle energy demand of buildings.

Energy conversion factors [and life cycle costing and cost analysis papers] /

Mode of access: Internet.

Using input-output data in life cycle inventory analysis

The impacts on the environment from human activities are of increasing concern. The need to consider the reduction in energy consumption is of particular interest, especially in the construction and operation of buildings, which accounts for between 30 and 40% of Australia's national energy consumption. Much past and more recent emphasis has been placed on methods for reducing the energy consumed in the operation of buildings. With the energy embodied in these buildings having been shown to account for an equally large proportion of a building's life cycle energy consumption, there is a need to look at ways of reducing the embodied energy of buildings and related products. Life cycle assessment (LCA) is considered to be the most appropriate tool for assessing the life cycle energy consumption of buildings and their products. The life cycle inventory analysis (LCIA) step of a LCA, where an inventory of material and energy inputs is gathered, may currently suffer from several limitations, mainly concerned with the use of incomplete and unreliable data sources and LCIA methods. These traditional methods of LCIA include process-based and input-output-based LCIA. Process-based LCIA uses process specific data, whilst input-output-based LCIA uses data produced from an analysis of the flow of goods and services between sectors of the Australian economy, also known as input-output data. With the incompleteness and unreliability of these two respective methods in mind, hybrid LCIA methods have been developed to minimise the errors associated with traditional LCIA methods, combining both process and input-output data. Hybrid LCIA methods based on process data have shown to be incomplete. Hybrid LCIA methods based on input-output data involve substituting available process data into the input-output model minimising the errors associated with process-based hybrid LCIA methods. However, until now, this LCIA method had not been tested for its level of completeness and reliability. The aim of this study was to assess the reliability and completeness of hybrid life cycle inventory analysis, as applied to the Australian construction industry. A range of case studies were selected in order to apply the input-output-based hybrid LCIA method and evaluate the subsequent results as obtained from each case study. These case studies included buildings: two commercial office buildings, two residential buildings, a recreational building; and building related products: a solar hot water system, a building integrated photovoltaic system and a washing machine. The range of building types and products selected assisted in testing the input-output-based hybrid LCIA method for its applicability across a wide range of product types. The input-output-based hybrid LCIA method was applied to each of the selected case studies in order to obtain their respective embodied energy results. These results were then evaluated with the use of a number of evaluation methods. These evaluation methods included an analysis of the difference between the process-based and input-output-based hybrid LCIA results as an evaluation of the completeness of the process-based LCIA method. The second method of evaluation used was a comparison between equivalent process and input-output values used in the input-output-based hybrid LCIA method as a measure of reliability. It was found that the results from a typical process-based LCIA and process-based hybrid LCIA have a large gap when compared to input-output-based hybrid LCIA results (up to 80%). This gap has shown that the currently available quantity of process data in Australia is insufficient. The comparison between equivalent process-based and input-output-based LCIA values showed that the input-output data does not provide a reliable representation of the equivalent process values, for material energy intensities, material inputs and whole products. Therefore, the use of input-output data to account for inadequate or missing process data is not reliable. However, as there is currently no other method for filling the gaps in traditional process-based LCIA, and as input-output data is considered to be more complete than process data, and the errors may be somewhat lower, using input-output data to fill the gaps in traditional process-based LCIA appears to be better than not using any data at all. The input-output-based hybrid LCIA method evaluated in this study has shown to be the most sophisticated and complete currently available LCIA method for assessing the environmental impacts associated with buildings and building related products. This finding is significant as the construction and operation of buildings accounts for a large proportion of national energy consumption. The use of the input-output-based hybrid LCIA method for products other than those related to the Australian construction industry may be appropriate, especially if the material inputs of the product being assessed are similar to those typically used in the construction industry. The input-output-based hybrid LCIA method has been used to correct some of the errors and limitations associated with previous LCIA methods, without the introduction of any new errors. Improvements in current input-output models are also needed, particularly to account for the inclusion of capital equipment inputs (i.e. the energy required to manufacture the machinery and other equipment used in the production of building materials, products etc.). Although further improvements in the quantity of currently available process data are also needed, this study has shown that with the current available embodied energy data for LCIA, the input-output-based hybrid LCIA appears to provide the most reliable and complete method for use in assessing the environmental impacts of the Australian construction industry.

Life cycle cost analysis of silicon and organic building integrated photovoltaic systems (BiPV)

Despite the undisputed benefits associated with photovoltaic (PV) technology, the financial barrier acts as the major hurdle before it is seen as a commercial competitive form of renewable energy. Many studies have been performed outlining the life cycle energy benefits of PV technology. However, there has been limited number of studies dedicated to the life cycle cost impacts. The aim of this paper is to identify whether life cycle cost analysis is the best approach to determining the cost contributors or savings associated with this technology. This paper has been structured similarly to previous life cycle energy studies to consider the cost implications involved within each area of the products lifecycle. Amongst many new developments, traditional silicon based units have been challenged by the introduction of new organic systems; and recent studies highlight that these systems offer major cost reductions. Based on an analysis of current literature, this paper identifies that the recent growth and development of both organic and silicon based systems have had a considerable effect on the cost of PV cells. The competitive nature of the renewable energy market will also impact on a life cycle cost analysis; and any potential findings will valid for a limited timeframe.

Plant oils as fuels for compression ignition engines: a technical review and life-cycle analysis

As an alternative fuel for compression ignition engines, plant oils are in principle renewable and carbon-neutral. However, their use raises technical, economic and environmental issues. A comprehensive and up-to-date technical review of using both edible and non-edible plant oils (either pure or as blends with fossil diesel) in CI engines, based on comparisons with standard diesel fuel, has been carried out. The properties of several plant oils, and the results of engine tests using them, are reviewed based on the literature. Findings regarding engine performance, exhaust emissions and engine durability are collated. The causes of technical problems arising from the use of various oils are discussed, as are the modifications to oil and engine employed to alleviate these problems. The review shows that a number of plant oils can be used satisfactorily in CI engines, without transesterification, by preheating the oil and/or modifying the engine parameters and the maintenance schedule. As regards life-cycle energy and greenhouse gas emission analyses, these reveal considerable advantages of raw plant oils over fossil diesel and biodiesel. Typical results show that the life-cycle output-to-input energy ratio of raw plant oil is around 6 times higher than fossil diesel. Depending on either primary energy or fossil energy requirements, the life-cycle energy ratio of raw plant oil is in the range of 2–6 times higher than corresponding biodiesel. Moreover, raw plant oil has the highest potential of reducing life-cycle GHG emissions as compared to biodiesel and fossil diesel.

Life-cycle analysis of energy and greenhouse gas emissions of automotive fuels in India: Part 2-Well-to-wheels analysis

In this second of the two-part study, the results of the Tank-to-Wheels study reported in the first part are combined with Well-to-Tank results in this paper to provide a comprehensive Well-to-Wheels energy consumption and greenhouse gas emissions evaluation of automotive fuels in India. The results indicate that liquid fuels derived from petroleum have Well-to-Tank efficiencies in the range of 75-85% with liquefied petroleum gas being the most efficient fuel in the Well-to-Tank stage with 85% efficiency. Electricity has the lowest efficiency of 20% which is mainly attributed due to its dependence on coal and 25.4% losses during transmission and distribution. The complete Well-to-Wheels results show diesel vehicles to be the most efficient among all configurations, specifically the diesel-powered split hybrid electric vehicle. Hydrogen engine configurations are the least efficient due to low efficiency of production of hydrogen from natural gas. Hybridizing electric vehicles reduces the Well-to-Wheels greenhouse gas emissions substantially with split hybrid configuration being the most efficient. Electric vehicles do not offer any significant improvement over gasoline-powered configurations; however a shift towards renewable sources for power generation and reduction in losses during transmission and distribution can make it a feasible option in the future. (C) 2015 Elsevier Ltd. All rights reserved.

Effects of ethanol on vehicle energy efficiency and implications on ethanol life-cycle greenhouse gas analysis.

Bioethanol is the world's largest-produced alternative to petroleum-derived transportation fuels due to its compatibility within existing spark-ignition engines and its relatively mature production technology. Despite its success, questions remain over the greenhouse gas (GHG) implications of fuel ethanol use with many studies showing significant impacts of differences in land use, feedstock, and refinery operation. While most efforts to quantify life-cycle GHG impacts have focused on the production stage, a few recent studies have acknowledged the effect of ethanol on engine performance and incorporated these effects into the fuel life cycle. These studies have broadly asserted that vehicle efficiency increases with ethanol use to justify reducing the GHG impact of ethanol. These results seem to conflict with the general notion that ethanol decreases the fuel efficiency (or increases the fuel consumption) of vehicles due to the lower volumetric energy content of ethanol when compared to gasoline. Here we argue that due to the increased emphasis on alternative fuels with drastically differing energy densities, vehicle efficiency should be evaluated based on energy rather than volume. When done so, we show that efficiency of existing vehicles can be affected by ethanol content, but these impacts can serve to have both positive and negative effects and are highly uncertain (ranging from -15% to +24%). As a result, uncertainties in the net GHG effect of ethanol, particularly when used in a low-level blend with gasoline, are considerably larger than previously estimated (standard deviations increase by >10% and >200% when used in high and low blends, respectively). Technical options exist to improve vehicle efficiency through smarter use of ethanol though changes to the vehicle fleets and fuel infrastructure would be required. Future biofuel policies should promote synergies between the vehicle and fuel industries in order to maximize the society-wise benefits or minimize the risks of adverse impacts of ethanol.