Architecture, Building and Planning - Research Publications

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    Towards zero life cycle GHG emissions apartment buildings in Lebanon
    Stephan, A ; Stephan, L (IOP Publishing, 2020-11-20)
    Abstract Buildings are one of the main drivers of greenhouse gas (GHG) emissions and their life cycle emissions need to be significantly reduced in order to address the unprecedented climate emergency. While there are numerous studies on zero operational energy and GHG emissions buildings, very few studies exist on buildings that aim to reach zero life cycle GHG emissions buildings. The apartment building typology is particularly challenging due to the very small roof area per apartment and the limited capacity for renewable energy generation. This study investigates a four-storey apartment building in Sehaileh, Lebanon and modifies it to reach zero life cycle GHG emissions through a series of measures targeting embodied and/or operational GHG emissions. Both a life cycle GHG emissions analysis and a life cycle cost analysis are conducted on all measures their combination, including the installation of a 50kWp photovoltaic array for the building. Results demonstrate that it is possible to achieve zero life cycle GHG emissions for that building typology and number of storeys, in a Lebanese Mediterranean climate, but at a net life cycle cost of ∼43 kUSD2020 over 50 years, compared to the base case guilding. Implications in terms of policy and further research are discussed.
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    The effect of data age on the assessment of a building’s embodied energy
    Crawford, R ; Stephan, A ; Ghaffarianhoseini, A ; Ghaffarianhoseini, A, A ; Nasmith, N (The Architectural Science Association (ANZAScA), 2020)
    Data used to quantify the embodied energy of a building, known as life cycle inventory (LCI) data, varies widely in temporal relevance. The energy associated with construction material production and building construction changes regularly due to improvements in manufacturing and construction processes, and energy mix and intensity. Older LCI data may not be representative of the current industry. Due to the time and costs involved in compiling LCIs, many studies rely on outdated data, yet no studies have considered the effect of data age on the analysis of a building’s embodied energy. A reliable embodied energy value is critical to ensure energy reduction efforts have been effective. This study compares the life cycle embodied energy of a typical Australian house using data from a 2010 and 2019 LCI database, compiled using an identical technique. The 2019 data lead to a 27.7% decrease in life cycle embodied energy. This reveals that the age of data may have a considerable effect on the value of a building’s embodied energy, indicating that LCI data should be regularly updated to respond to changes in manufacturing and construction processes as well as energy mix and intensity.
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    The life cycle embodied energy and greenhouse gas emissions of an Australian housing development: comparing 1997 and 2019 hybrid life cycle inventory data
    Allende, A ; Stephan, A ; Crawford, R ; Ghaffarianhoseini, A ; Ghaffarianhoseini, A ; Nasmith, N (The Architectural Science Association (ANZAScA), 2020)
    Data used to conduct a life cycle assessment, called a life cycle inventory (LCI), is rarely scrutinised and its effects on the results of an environmental assessment is understudied. Hybrid analysis is the most comprehensive technique to compile an LCI. It combines bottom-up industrial process data and top-down macroeconomic input-output data. This study compares two hybrid LCIs of construction materials, using the same technique, developed in 1997 and 2019. This paper evaluates the effect of LCI data on the life cycle embodied energy and greenhouse gas emissions of a recent housing development in Melbourne, Australia. The case study development consists of six different apartment buildings (~14,000m² gross floor area; 555 inhabitants) that have an improved environmental performance compared to business-as-usual. Results show that the 2019 LCI lead to a decrease in the life cycle embodied energy and greenhouse gas emissions over 50 years, from 39.1 GJ/m² to 32.2 GJ/m² (-17.6%) and from 2,338 kgCO2e/m² to 2,218 kgCO2e/m² (-5.1%), respectively. The embodied energy and greenhouse gas emissions ranking of some materials changed by up to five positions, while at the assembly level the top five assemblies did not change much. This analysis provides rare insights into the effects of hybrid LCI data on the life cycle assessment of built environment assets and implications for design.
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    EPiC: Introducing a database of hybrid environmental flow coefficients for construction materials
    Crawford, RH ; Stephan, A ; Prideaux, F (IOP Publishing, 2020-11-20)
    Abstract As worldwide consumption of materials continues to rise, there is growing pressure on material, energy and water resources and an increase in waste production and greenhouse gas emissions. A much more sustainable approach to the procurement of built assets is crucial to avoid exacerbating existing environmental pressures. Product and process-based environmental data is an important element in understanding how current and future built assets perform. This paper analyses environmental flow data for a range of construction materials contained within the Environmental Performance in Construction (EPiC) Database, a new, open access repository of hybrid environmental flow coefficients for construction materials. The structural paths of 131 construction materials are analysed to identify trends and contributors to embodied water, energy and greenhouse gas (GHG) emissions coefficients. The disaggregation and analysis of material coefficients shows the complexity of the material supply chains and provides insight into the key inputs and outputs resulting from the production of construction materials.
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    Tiny house, tiny footprint? The potential for tiny houses to reduce residential greenhouse gas emissions
    Crawford, RH ; Stephan, A (IOP Publishing, 2020-11-20)
    Abstract While considerable improvements to the energy efficiency of housing have been achieved over recent decades, the residential sector still represents a significant and increasing proportion of global greenhouse gas emissions. This is exacerbated by an increasing global population and living standards, demand for larger houses, and smaller household size. Tiny houses have emerged as a potential solution to this issue. While research exists on the environmental benefits of smaller housing, there is little on that of tiny houses. This study quantifies the life cycle GHG emissions of a tiny house, and their potential to reduce residential GHG emissions. A hybrid analysis and a dynamic energy modelling tool were used to quantify embodied and operational GHG emissions, respectively, for a tiny house located in Australia. The study shows that a tiny house may result in a 70% reduction in per capita GHG emissions over its life compared to a traditional Australian house. This indicates the potential of tiny houses to be a useful option for reducing GHG emissions in the building sector.
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    The influence of life cycle inventory approaches on the choice of structural systems to reduce the embodied greenhouse gas emissions of tall buildings
    Helal, J ; Stephan, A ; Crawford, RH (IOP Publishing, 2020-11-20)
    Abstract The construction of tall buildings generates a high spatial and temporal concentration of greenhouse gas (GHG) emissions. Research has shown that as building height increases, more resources per floor area are required to withstand the increasing effects of wind and earthquake loads. This has major implications for the environmental performance of tall buildings since the embodied GHG emissions (EGHGE) of structural systems tend to represent the greatest portion of the life cycle GHG emissions of tall buildings. In mitigating the effects of climate change, life cycle assessment (LCA) has been proposed as an early stage design tool to facilitate the choice of structural systems for tall buildings. However, international standards on LCA do not specify which of the three main life cycle inventory (LCI) approaches to use - process analysis, environmentally-extended input-output analysis or hybrid analysis. The aim of this paper is to evaluate the influence of LCI approaches on the choice of structural systems for tall buildings to minimise their embodied GHG emissions. The effects of LCI approaches on the choice of structural systems for tall buildings are evaluated using 10 tall buildings, ranging in height from 10 to 50 storeys, parametrically designed using finite element modelling. Two alternative structural systems are proposed and various LCI approaches are used to compare their EGHGE. The paper demonstrates that varying the LCI approach can significantly influence the values of EGHGE of structural systems for tall buildings by up to 116%. Notably, the paper demonstrates that, in minimising EGHGE, the adopted LCI approach can influence the choice of structural systems for tall buildings. The findings of this study confirm the need for clarity, transparency and comprehensiveness in the use of LCI approaches for comparative LCA studies, particularly in the structural design of tall buildings.
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    Towards a design framework for the structural systems of tall buildings that considers embodied greenhouse gas emissions
    Helal, J ; Stephan, A ; Crawford, RH ; Cruz, PJS (CRC Press, 2019-07-29)
    During the 1960s, the Bangladeshi-American structural engineer and architect Fazlur Rahman Khan proposed an influential design framework for the structural systems of tall buildings titled premium-for-height. Khan argued that the challenge of a structural engineer is to design structural systems that minimise the increase in structural material weight per gross floor area with increasing building height. However, in meeting the challenges of climate change and urbanisation, minimising the embodied environmental flows of tall buildings must also be a priority in structural design frameworks. This paper proposes to expand the premium-for-height framework for tall buildings by considering the embodied greenhouse gas emissions of structural systems using a hybrid life cycle inventory analysis method. Advanced structural analysis and a comprehensive consideration of building parameters are also proposed. To demonstrate the use and potential of the framework, embodied greenhouse gas emissions of six case study tall buildings are analysed. The results arediscussed and recommendations are made to improve the reliability of the more comprehensive framework.
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    A comprehensive database of environmental flow coefficients for construction materials: closing the loop in environmental design
    Crawford, RH ; Stephan, A ; Prideaux, F ; Agrawal, A (The Architectural Science Association, 2019)
    Life cycle assessment is increasingly used to quantify and reduce the environmental effects of buildings. Embodied environmental effects, resulting from material production and replacement as well as construction, are typically quantified using coefficients from readily available databases. However, most existing databases of embodied environmental coefficients for construction materials suffer from limitations, such as inconsistency in the life cycle inventory method used or system boundary incompleteness. This paper introduces a new database of hybrid environmental flow coefficients for construction materials, covering flows of energy, water and greenhouse gas emissions for over 100 common construction materials. The hybrid approach used combines bottom-up industrial process data and top-down macroeconomic input-output data, making it more comprehensive than process analysis and more accurate and specific than input-output analysis alone. A case study building is used to demonstrate the importance of using hybrid coefficients for improving environmental performance. This study shows that the use of process coefficients can lead to a significant underestimation of the total environmental effects associated with the construction of a building, by up to 64%. This has considerable implications for decision-making relating to building design, including the focus of improvement efforts. This database of coefficients will enable building professionals to more effectively analyse and improve the environmental performance of buildings. This will also help inform the focus of environmental policy and improve the implementation of life cycle thinking in environmental design.
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    Beyond the “premium-for-height” framework for designing the structural systems of tall buildings
    Helal, J ; Stephan, A ; Crawford, RH ; Rajagopalan, P (The Architectural Science Association and RMIT University, 2018)
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    Establishing a comprehensive database of construction material environmental flow coefficients for Australia
    Crawford, RH ; Bontinck, P-A ; Stephan, A ; Rajagopalan, P (The Architectural Science Association and RMIT University, 2018)