Architecture, Building and Planning - Research Publications
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ItemBuilding service life and its effect on the life cycle embodied energy of buildings(Elsevier, 2015)The building sector is responsible for significant energy demands. An understanding of where this occurs across the building life cycle is critical for optimal targeting of energy reduction efforts. The energy embodied in a building can be significant, yet is not well understood, especially the on-going ‘recurrent’ embodied energy associated with material replacement and building refurbishment. A key factor affecting this ‘recurrent’ embodied energy is a building's service life. The aim of this study was to investigate the relationship between the service life and the life cycle embodied energy of buildings. The embodied energy of a detached residential building was calculated for a building service life range of 1–150 years. The results show that variations in building service life can have a considerable effect on the life cycle embodied energy demand of a building. A 29% reduction in life cycle embodied energy was found for the case study building by extending its life from 50 to 150 years. This indicates the importance of including recurrent embodied energy in building life cycle energy analyses as well as integrating building service life considerations when designing and managing buildings for improved energy performance.
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ItemComparing a territorial-based and a consumption-based approach to assess the local and global environmental performance of cities(Elsevier, 2018)In the framework of pressing local and global environmental challenges it is essential to understand that cities are complex systems dependent on and linked to the rest of the world through global supply chains that embody an array of environmental flows. Cities are thus a complex articulation that intertwine local and global challenges which rely at their extended hinterland for their resource use and pollution emission. To assess the environmental sustainability of an urban area in a comprehensive manner, it is not only necessary to measure its local and direct environmental performance but also to understand and take into account its global and indirect environmental counterparts. This paper presents a comparative analysis of a territorial-based and a consumption-based approach to estimate both direct and embodied resource use and pollution flows for the case of Brussels Capital Region (Belgium). The territorial-based approach is based on local energy, water and material consumption measured data as well as measured data on waste generation and pollution emissions. The estimation of indirect resource use and pollution emissions (or consumption-based approach) is based on the regional IO-tables of the city-region of Brussels extended with multi-region input-output tables, taking into account the global flows of consumption. The comparison of these two approaches is particularly relevant in the case of cities that have limited productive activities and limited or no extraction of materials as the impact on the hinterland is often underestimated or neglected by local (environmental) policies which are only based on territorial-based figures. The results show that the indirect primary energy use, GHG emissions and material use estimated by the consumption-based approach is more than three times higher than local measures indicate. The embodied water use, estimated via IOA, was over 40 times higher than the local water consumption. These results show that territorial-based approach using local data underestimate the resource needs and pollution emissions of a city and can therefore be insufficient or even be misguiding. By mapping the origin of embodied flows it is in fact possible to illustrate the open character of an urban economy and its dependence on the global hinterland. Finally, this paper discusses the possibility and relevance to combine these two approaches to create a hybrid framework that measures the full environmental performance of cities both accurately and comprehensively.
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ItemDirectionally selective shading control in maritime sub-tropical and temperate climates: Life cycle energy implications for office buildings(Elsevier, 2016)Scheduling directionally selective shading devices to increase or decrease their level of occlusion relative to the total incoming solar radiation has the benefit of controlling solar heat gain during a variety of sky conditions and allowing more constant illuminance levels to be achieved within a building. In this study, hourly sky condition and annual solar angles were used to describe the tilt of the slats of an external directionally selective shading control for an external venetian blind on an office building in Melbourne and Brisbane, Australia. The life cycle energy demand associated with this shading control was compared to a static base case with an external overhang and internal venetians. The analysis was extended to the HVAC system which was sized to account for the effect of the shading on solar gain and the artificial lighting requirement. It was found that the embodied energy of the HVAC and shading components accounted for between 21.7% and 25.5% of the total life cycle energy of these systems over 25 years. There was a reduction in embodied and operational energy requirements over a 25 year life cycle for the external venetian blind control of 24.9% for Melbourne and 24.0% for Brisbane relative to the static base case. Based on the simulation results, office buildings with equator facing facades located in similar climates and latitudes may have the potential for equivalent life cycle energy reductions when external directionally selective shading controls are employed to moderate overheating and daylighting.
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ItemThe economic value of low-energy housing(Taylor and Francis, 2016-01-01)This paper explores a new perspective towards understanding barriers to ascertaining the economic value of low-energy housing. It examines why the economic value of low-energy housing is less transparent in active markets; this is investigated from the valuation principle perspectives of embodied energy and operational energy in residential dwellings. The focus is placed on the composition of energy consumption associated with the housing product life cycle. Low operational energy of a dwelling is linked to consumer preference by the inter-temporal value estimate of expected benefits. However, “low” embodied energy housing is an ecological construct and does not appear to be directly linked to short-term market value or an expected (intuitive) economic motive. This “gap/disconnect”, alongside some practical “barriers” in the market economy, has created a challenge in deriving the economic value of low-energy housing. The barrier to economic value of low-energy housing is methodological and by adopting a life cycle approach to assessing and measuring energy in a house that incorporates embodied energy and operational energy, greater clarity can be achieved which may lead to a better informed market, enhancing transparency and allowing consumer choice to direct and value the broader benefits of low-energy housing.
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ItemBarriers to improving the environmental performance of construction waste management in remote communities(Elsevier, 2017)The construction sector represents one of the most significant contributors to global waste production and is responsible for over 30% of the waste that ends up in landfill. Sending construction waste to landfill results in a broad range of environmental consequences including: degradation of land, habitat destruction, contamination of soil and groundwater, and release of methane. There is a growing awareness of the need to divert construction and demolition (C&D) waste from landfill for reuse or recycling. This helps maximise the value of the resources embodied in these materials and reduce the demand for virgin raw materials and the associated environment effects resulting from their extraction, processing and manufacture. However, diversion of C&D waste to reuse or recycling in remote communities can be difficult and costly. This poses a significant challenge for improving the environmental performance of construction waste management in these communities. A housing refurbishment project in Alice Springs, a remote town in central Australia, was used to identify the barriers associated with improving the environmental performance of construction waste management in remote communities. This study considers the materials removed as part of the demolition phase of the project. Material types and quantities were documented and on-site and off-site waste management practices observed. Reasons for waste management decisions were recorded. The study identified a range of barriers to improving the environmental performance of construction waste management in remote communities. These include cost and time associated with on-site waste management, industry culture, lack of education, competing project priorities, and lack of financial incentive. Greater incentives to encourage the diversion of C&D waste from landfill are needed, in particular. This and other strategies for improving construction waste management practices in remote communities must be targeted at the context of individual communities though, due to their unique characteristics.
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ItemDeveloping an integrated framework for assessing the life cycle greenhouse gas emissions and life cycle cost of buildings(Elsevier, 2017)With building-related greenhouse gas emissions(GHGE) having more than doubled since 1970, they represent one of the largest and most attractive opportunities for climate change mitigation. However, current focus has mainly been on reducing operational GHGE leaving building embodied GHGE (i.e. the GHG emissions associated with the extraction, manufacture and transportation of materials, and the building construction process itself) largely ignored. These embodied emissions have been estimated to represent between 10% to 97% of a buildings total life cycle GHGE. It is thus critical that decision-making in relation to buildings is based on a life cycle perspective. One of the main barriers to this approach is the uncertainty surrounding the financial implications of life cycle GHGE reduction strategies. Despite project cost being a key driver for decision-making, building developers, designers and owners have insufficient knowledge or appropriate tools to adequately consider these life cycle costs and balance them against GHGE savings. Several methods exist for quantifying the costs of a building, such as life cycle costing (LCC). However, LCC and life cycle GHGE assessments are often used in isolation. This study will address the urgent need to move towards integrating these assessments by developing a framework that can be used to ascertain the important relationships and trade-offs between financial and GHGE performance of various building-related GHGE reduction strategies. This framework can be used as part of the building decision-making process and help create a low carbon, affordable built environment.
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ItemComparative assessment of embodied energy of recycled aggregate concrete(Elsevier, 2017)Concrete waste can be recycled to produce an aggregate product; referred to as recycled concrete aggregate (RCA). While RCA is mainly used as a road base filler material, it has the potential to replace natural coarse aggregate (NA) in structural concrete. In determining the environmental performance of the resultant concrete product from this substitution, referred to as recycled aggregate concrete (RAC) against its counterpart, natural aggregate concrete (NAC), it is important to consider the effects of the entire life cycle including the upstream processes associated with each. This paper evaluates “cradle-to-gate” embodied energy (EE) of RAC received at a construction site, in comparison to NAC, using the input-output-based hybrid approach, using an Australian context. The paper constructs a model to evaluate EE of RAC and analyses the incremental energy of RAC as opposed to NAC, to identify what contribute to the difference out of four primary factors discussed in previous research. It was found that the EE of RAC is marginally different to that of NAC by +2.1 to −1.1%, and the variation was subject to the magnitude and direction of the four factors considered. The mix composition, primarily the binder composition, was found to have the highest contribution to the difference, significantly standing out from the direct energy difference between RCA and NA, difference of sourcing distance between RCA and NA and the difference of direct manufacturing energy between RAC and NAC.
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ItemA framework for assessing the environmental benefits of mass timber construction(Elsevier, 2017)The construction industry represents one of the most significant contributors to human-induced environmental damage. Many of the negative consequences on the environment result from the extraction, processing and manufacture of construction materials and components. This includes the depletion of raw material, energy and water resources; loss of habitats; contamination of water and soil; reduced air quality; and climate change. The production of some of the most common construction materials, such as concrete, steel, glass and aluminum are of most critical concern. There is a growing awareness of the need for a greater use of renewable materials that not only reduce resource depletion, but also address the range of other environmental issues. Cellulose-based materials, such as timber and straw are a commonly used renewable alternative. While timber has been used in construction for many centuries, there has been a recent resurgence in the use of timber as a replacement for traditional concrete and steel structures, particularly in response to these pressing environmental imperatives. Mass timber construction (MTC) is seen as a potentially viable alternative for dealing with these issues while at the same time meeting the demands of modern buildings, such as increasing height, speed of construction and fire resistance. Most existing research on MTC has been centered on its structural performance and fire resistance. There is a general lack of understanding of how this form of construction performs from an environmental perspective, which is critical given this is considered as one of its main strengths. This study establishes a framework for assessing the environmental benefits of MTC. The aim is to provide a streamlined approach to enable key building project stakeholders to assess the potential for MTC to provide environmental benefits over traditional construction methods in a particular building project. This can provide useful guidance for decision-making in relation to the use of MTC.
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ItemImproving the uptake of hybrid life cycle assessment in the construction industry(Elsevier, 2017)With building-related greenhouse gas emissions(GHGE) having more than doubled since 1970, they represent one of the largest and most attractive opportunities for climate change mitigation. However, current focus has mainly been on reducing operational GHGE leaving building embodied GHGE (i.e. the GHG emissions associated with the extraction, manufacture and transportation of materials, and the building construction process itself) largely ignored. These embodied emissions have been estimated to represent between 10% to 97% of a buildings total life cycle GHGE. It is thus critical that decision-making in relation to buildings is based on a life cycle perspective. One of the main barriers to this approach is the uncertainty surrounding the financial implications of life cycle GHGE reduction strategies. Despite project cost being a key driver for decision-making, building developers, designers and owners have insufficient knowledge or appropriate tools to adequately consider these life cycle costs and balance them against GHGE savings. Several methods exist for quantifying the costs of a building, such as life cycle costing (LCC). However, LCC and life cycle GHGE assessments are often used in isolation. This study will address the urgent need to move towards integrating these assessments by developing a framework that can be used to ascertain the important relationships and trade-offs between financial and GHGE performance of various building-related GHGE reduction strategies. This framework can be used as part of the building decision-making process and help create a low carbon, affordable built environment.
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ItemMethodology for the integrated assessment on the use of recycled concrete aggregate replacing natural aggregate in structural concrete(Elsevier, 2017)Recycled concrete waste in the form of recycled concrete aggregate (RCA) is presently used mostly as a road base filler in Australia. However, instead of producing natural aggregate (NA) to manufacture natural aggregate concrete (NAC) to use in structural concrete, there is potential to use RCA to manufacture recycled aggregate concrete (RAC). While the material performance of RAC compared to NAC is analysed in the existing literature, it is not evident whether the use of RCA in structural concrete results in financial and environmental benefits. Previous literature analysing these aspects mostly focuses on a single area of investigation. This paper presents an integrated methodology for the assessment of the use of RCA replacing NA in structural concrete, considering technical, financial, environmental and social perspectives. Cost-benefit assessment (CBA) has been used to evaluate the internalised impacts as well as external costs concerning the use of both RAC and NAC. The scope of each discipline-focused assessment is presented demarcating the relevant scope for further study, and the specific tools and methodologies to be adopted are specified. Finally, amalgamating the different discipline-focused assessments, a unique approach for comparing a sustainable, alternative raw material for concrete, is presented in this paper.