Nalanie Mithraratne | Massey University (original) (raw)
Journal Papers by Nalanie Mithraratne
Temporary housing is crucial to disaster recovery, due to the demand for large numbers within a s... more Temporary housing is crucial to disaster recovery, due to the demand for large numbers within a short period. The short life cycle and unique functional requirements associated with temporary housing could lead to significant environmental impacts. However these have not been adequately investigated. This paper focuses on the life cycle performance of light-framed temporary housing in China with local technologies, taking Chinese electricity mix of each process and domestic transportation distances into consideration. The research selects four popular temporary housing in China, calculates the material requirements and compares the life cycle impact of different wall assemblies based on Future House built in Nanjing. While energy consumption and greenhouse gas emissions are used as surrogate indicators of environmental impact, total life-time impact is established by including construction energy, operating energy, maintenance energy and end-of-life energy and corresponding greenhouse gas emissions. It was found that the life cycle energy of post-disaster temporary housing is much higher in comparison to low energy buildings with construction energy contributing 65% to life cycle energy due to unique requirements. The results also show that life cycle energy of post-disaster shelters could be reduced by using recycled materials, lighter structural materials and light wall cladding materials.
Green roofs and walls are increasingly being incorporated in urban centers to enhance visual appe... more Green roofs and walls are increasingly being incorporated in urban centers to enhance visual appeal and
livability. However, holistic evaluations that quantify environmental, social, and financial implications of these measures
are limited, as well as those that use a long-term perspective. At the same time, the discussion tends to revolve around the
perceived benefits rather than the established or quantified ones. This paper, using a holistic evaluation of a project that
received the Singapore Skyrise Greenery Platinum award in 2011, argues that the strength of the case for adopting or
incentivising green strategies in high-rise buildings in the city-state is negative from a resource- and cost-footprint
perspective. Assessment methods to quantify social values of the greenery strategies in buildings, such as therapeutic and
biophilic benefits, are currently non-existent, as the established evaluation methods such as life cycle assessment focus on
the production stages rather than the use phase. While the results reported here stem mainly from the inherited building
characteristics, incorporating these greenery strategies at the early design stages and using a careful system design can
reduce the burden.
Study energy-saving potential of semi-transparent BIPV windows in Singapore buildings;.Six module... more Study energy-saving potential of semi-transparent BIPV windows in Singapore buildings;.Six modules were simulated with previously measured properties;.Results indicate positive and negative electrical benefits, with double-glazed modules performing better;.All modules exhibit better energy-efficiency as compared to common window technologies;.Results suggest that semi-transparent BIPV windows may have potential to increase high-rise buildings’ energy efficiency.Buildings consume large amounts of energy and semi-transparent building-integrated photovoltaic (BIPV) has the potential to increase their energy efficiency. BIPV windows affect building energy consumption through solar heat gain, daylighting and electricity production. This study examines six commercially-available semi-transparent BIPV windows; four single-glazed and two double-glazed. A new index was formulated to evaluate the overall energy performance of semi-transparent BIPV in terms of increase/decrease of cooling energy, artificial lighting energy and generation of electricity. Parametric simulation studies based on different window-to-wall ratios and orientations to obtain annual energy consumption was performed for the case of Singapore. Selected results of semi-transparent BIPVs were also compared against commonly used window types such as single-glazing, doubled-glazing and low-emissivity windows. The results showed the potential to adopt semi-transparent BIPV across all orientations in tropical countries such as Singapore. A variety of design strategies optimizing the window-wall-ratio for various orientations will be necessary to achieve the highest electricity benefit with different modules.
Microgeneration using roof-top wind turbines is at present not common in New Zealand. It is, howe... more Microgeneration using roof-top wind turbines is at present not common in New Zealand. It is, however, being trialled by the electricity network company, Vector, in a range of urban locations. Limitations of size mean roof-top wind turbines may not satisfy the total energy requirement of New Zealand houses. Ensuring structural stability and complying with stringent noise standards in New Zealand are further issues. In addition, roof-top turbines may be inefficient in terms of net energy and carbon emissions, performance indicators that are fundamental for the adoption of this technology. This paper considers the feasibility of using roof-top wind turbines in urban houses in New Zealand and, using life cycle assessment, evaluates the net energy and carbon emissions associated with their use. The results indicate that the electricity-generating potential of centralised wind farms in New Zealand using large turbines is 11.3–7 times the generating potential of roof-top turbines mounted on urban houses. In spite of this the roof-top turbines that are currently being trialled, could have the potential to reduce the energy and carbon intensity of New Zealand electricity by 81% and 26%, respectively.
Research on urban development to date has tended to focus on buildings and their performance in t... more Research on urban development to date has tended to focus on buildings and their performance in terms of associated energy and environmental impacts. Although, many detailed studies of residential buildings have been carried out, these studies usually concentrate on the house itself without consideration of the infrastructure systems. Alternatives to traditional infrastructure systems are necessary due to increasing demand for sustainable development. Life cycle analysis is a tool which is capable of evaluating ...
The state of the physical sustainability of any residential development is influenced by its spat... more The state of the physical sustainability of any residential development is influenced by its spatial organization. The design most suited for the infrastructure systems which serve a particular development in turn would depend on the number of dwelling units in a settlement and the number of occupants in each dwelling unit. Infrastructure development could either be a new installation or an addition to an existing system, and the best option for either case would be quite different. This paper evaluates the extent to which the spatial characteristics of residential developments determine the kind of infrastructure system that can be employed based on water supply for a series of urban settlements with varying residential densities, in Auckland, New Zealand. The true cost of water supply systems is assessed using a life cycle approach, which incorporates not only the initial construction but also maintenance, replacement and final demolition of systems over the useful life. Residential density/settlement patterns most conducive for mains water supply are identified in terms of life-cycle energy and carbon dioxide emissions by detailed analysis of various land use patterns and the existing mains water supply system in Auckland.
Globally designers are concentrating on minimising the impact their buildings make on the environ... more Globally designers are concentrating on minimising the impact their buildings make on the environment. Although many claim their buildings to be sustainable, unless an objective analysis is carried out, it is not possible to determine the impact that a particular building has on the environment. This paper describes a method that has been developed at the University of Auckland for a detailed life cycle analysis of an individual house in New Zealand based on the embodied and operating energy requirements and life cycle cost over the useful life of the building.
Conference Papers by Nalanie Mithraratne
Paper presented at the Construction & Deconstruction: Building Today Saving Tomorrow Conference
Construction and demolition waste represents a significant wastage of natural resources and energ... more Construction and demolition waste represents a significant wastage of natural resources and energy while also contributing to air pollution. Measures to reduce construction waste include flexibility in design of new buildings and recovery of materials and components from existing buildings or adaptation of existing buildings to new uses. Although prolonging the building life through designing for adaptation can reduce the rate of demolition, the low rate of renewal of buildings means that material recovery and whole building reuse are equally important in minimising construction waste. While quality of recovered material/component depends on the original design and recovery process, there is a lack of measures to promote the use of recovered materials. Changes in decision making on how buildings are designed, demolished and reused can therefore significantly improve the resilience of building stock and reduce the adverse impacts. While theoretical underpinnings of designing for deconstruction or adaptation of existing buildings are well established, their practice depends more on location, policy issues and incentives. The paper discusses the preliminary findings from a research project which aims to develop a set of guidelines on designing for flexibility based on life-time environmental and financial performance of alternative strategies and generate data on relative environmental performance of recovered construction materials/components compared with their virgin alternatives used in Singapore.
Paper presented at ‘Fifth International Conference on The Constructed Environment’
Green roofs and walls are increasingly being incorporated in urban centers to enhance visual appe... more Green roofs and walls are increasingly being incorporated in urban centers to enhance visual appeal and livability. However, holistic evaluations, that quantify environmental, social as well as financial implications of these measures, are limited, let alone those that use a long term perspective. At the same time, the discussion tends to revolve around the perceived benefits rather than the established or quantified.
This paper, using a holistic evaluation of a project that received Singapore Skyrise Greenery Platinum award in 2011, argues that the strength of the case for adopting or incentivising green strategies in high-rise buildings in the city state is negative from a resource and cost footprint perspective. Assessment methods to quantify social values of the greenery strategies in buildings, such as therapeutic and biophilic benefits, are currently non-existent as the established evaluation methods such as life cycle assessment focus on the production stages rather than the use phase.
While the results reported here stem mainly from the inherited building characteristics, incorporating these greenery strategies at the early design stages and the careful system design can reduce the burden.
Proceedings of 3rd New Zealand Life Cycle Association Conference, Sep 3, 2014
Proceedings of the Sustainable Buildings – Construction, Production and Technologies
Proceedings of the SB13 Singapore: Realising Sustainability in the tropics , Sep 9, 2013
Proceedings iNTA 2012 Conference: Tropics 2050
Proceedings iNTA 2012 Conference: Tropics 2050, 2012
Proceedings of 2nd Computational Design in Engineering Conference, LCA: A business compass for sustainable development
PLEA 2012 Conference: Opportunities, limits and needs towards an environmentally responsive architecture
Proceedings of 2nd New Zealand Life Cycle Assessment Conference, LCA: A business compass for sustainable development
SB07 New Zealand Conference
Temporary housing is crucial to disaster recovery, due to the demand for large numbers within a s... more Temporary housing is crucial to disaster recovery, due to the demand for large numbers within a short period. The short life cycle and unique functional requirements associated with temporary housing could lead to significant environmental impacts. However these have not been adequately investigated. This paper focuses on the life cycle performance of light-framed temporary housing in China with local technologies, taking Chinese electricity mix of each process and domestic transportation distances into consideration. The research selects four popular temporary housing in China, calculates the material requirements and compares the life cycle impact of different wall assemblies based on Future House built in Nanjing. While energy consumption and greenhouse gas emissions are used as surrogate indicators of environmental impact, total life-time impact is established by including construction energy, operating energy, maintenance energy and end-of-life energy and corresponding greenhouse gas emissions. It was found that the life cycle energy of post-disaster temporary housing is much higher in comparison to low energy buildings with construction energy contributing 65% to life cycle energy due to unique requirements. The results also show that life cycle energy of post-disaster shelters could be reduced by using recycled materials, lighter structural materials and light wall cladding materials.
Green roofs and walls are increasingly being incorporated in urban centers to enhance visual appe... more Green roofs and walls are increasingly being incorporated in urban centers to enhance visual appeal and
livability. However, holistic evaluations that quantify environmental, social, and financial implications of these measures
are limited, as well as those that use a long-term perspective. At the same time, the discussion tends to revolve around the
perceived benefits rather than the established or quantified ones. This paper, using a holistic evaluation of a project that
received the Singapore Skyrise Greenery Platinum award in 2011, argues that the strength of the case for adopting or
incentivising green strategies in high-rise buildings in the city-state is negative from a resource- and cost-footprint
perspective. Assessment methods to quantify social values of the greenery strategies in buildings, such as therapeutic and
biophilic benefits, are currently non-existent, as the established evaluation methods such as life cycle assessment focus on
the production stages rather than the use phase. While the results reported here stem mainly from the inherited building
characteristics, incorporating these greenery strategies at the early design stages and using a careful system design can
reduce the burden.
Study energy-saving potential of semi-transparent BIPV windows in Singapore buildings;.Six module... more Study energy-saving potential of semi-transparent BIPV windows in Singapore buildings;.Six modules were simulated with previously measured properties;.Results indicate positive and negative electrical benefits, with double-glazed modules performing better;.All modules exhibit better energy-efficiency as compared to common window technologies;.Results suggest that semi-transparent BIPV windows may have potential to increase high-rise buildings’ energy efficiency.Buildings consume large amounts of energy and semi-transparent building-integrated photovoltaic (BIPV) has the potential to increase their energy efficiency. BIPV windows affect building energy consumption through solar heat gain, daylighting and electricity production. This study examines six commercially-available semi-transparent BIPV windows; four single-glazed and two double-glazed. A new index was formulated to evaluate the overall energy performance of semi-transparent BIPV in terms of increase/decrease of cooling energy, artificial lighting energy and generation of electricity. Parametric simulation studies based on different window-to-wall ratios and orientations to obtain annual energy consumption was performed for the case of Singapore. Selected results of semi-transparent BIPVs were also compared against commonly used window types such as single-glazing, doubled-glazing and low-emissivity windows. The results showed the potential to adopt semi-transparent BIPV across all orientations in tropical countries such as Singapore. A variety of design strategies optimizing the window-wall-ratio for various orientations will be necessary to achieve the highest electricity benefit with different modules.
Microgeneration using roof-top wind turbines is at present not common in New Zealand. It is, howe... more Microgeneration using roof-top wind turbines is at present not common in New Zealand. It is, however, being trialled by the electricity network company, Vector, in a range of urban locations. Limitations of size mean roof-top wind turbines may not satisfy the total energy requirement of New Zealand houses. Ensuring structural stability and complying with stringent noise standards in New Zealand are further issues. In addition, roof-top turbines may be inefficient in terms of net energy and carbon emissions, performance indicators that are fundamental for the adoption of this technology. This paper considers the feasibility of using roof-top wind turbines in urban houses in New Zealand and, using life cycle assessment, evaluates the net energy and carbon emissions associated with their use. The results indicate that the electricity-generating potential of centralised wind farms in New Zealand using large turbines is 11.3–7 times the generating potential of roof-top turbines mounted on urban houses. In spite of this the roof-top turbines that are currently being trialled, could have the potential to reduce the energy and carbon intensity of New Zealand electricity by 81% and 26%, respectively.
Research on urban development to date has tended to focus on buildings and their performance in t... more Research on urban development to date has tended to focus on buildings and their performance in terms of associated energy and environmental impacts. Although, many detailed studies of residential buildings have been carried out, these studies usually concentrate on the house itself without consideration of the infrastructure systems. Alternatives to traditional infrastructure systems are necessary due to increasing demand for sustainable development. Life cycle analysis is a tool which is capable of evaluating ...
The state of the physical sustainability of any residential development is influenced by its spat... more The state of the physical sustainability of any residential development is influenced by its spatial organization. The design most suited for the infrastructure systems which serve a particular development in turn would depend on the number of dwelling units in a settlement and the number of occupants in each dwelling unit. Infrastructure development could either be a new installation or an addition to an existing system, and the best option for either case would be quite different. This paper evaluates the extent to which the spatial characteristics of residential developments determine the kind of infrastructure system that can be employed based on water supply for a series of urban settlements with varying residential densities, in Auckland, New Zealand. The true cost of water supply systems is assessed using a life cycle approach, which incorporates not only the initial construction but also maintenance, replacement and final demolition of systems over the useful life. Residential density/settlement patterns most conducive for mains water supply are identified in terms of life-cycle energy and carbon dioxide emissions by detailed analysis of various land use patterns and the existing mains water supply system in Auckland.
Globally designers are concentrating on minimising the impact their buildings make on the environ... more Globally designers are concentrating on minimising the impact their buildings make on the environment. Although many claim their buildings to be sustainable, unless an objective analysis is carried out, it is not possible to determine the impact that a particular building has on the environment. This paper describes a method that has been developed at the University of Auckland for a detailed life cycle analysis of an individual house in New Zealand based on the embodied and operating energy requirements and life cycle cost over the useful life of the building.
Paper presented at the Construction & Deconstruction: Building Today Saving Tomorrow Conference
Construction and demolition waste represents a significant wastage of natural resources and energ... more Construction and demolition waste represents a significant wastage of natural resources and energy while also contributing to air pollution. Measures to reduce construction waste include flexibility in design of new buildings and recovery of materials and components from existing buildings or adaptation of existing buildings to new uses. Although prolonging the building life through designing for adaptation can reduce the rate of demolition, the low rate of renewal of buildings means that material recovery and whole building reuse are equally important in minimising construction waste. While quality of recovered material/component depends on the original design and recovery process, there is a lack of measures to promote the use of recovered materials. Changes in decision making on how buildings are designed, demolished and reused can therefore significantly improve the resilience of building stock and reduce the adverse impacts. While theoretical underpinnings of designing for deconstruction or adaptation of existing buildings are well established, their practice depends more on location, policy issues and incentives. The paper discusses the preliminary findings from a research project which aims to develop a set of guidelines on designing for flexibility based on life-time environmental and financial performance of alternative strategies and generate data on relative environmental performance of recovered construction materials/components compared with their virgin alternatives used in Singapore.
Paper presented at ‘Fifth International Conference on The Constructed Environment’
Green roofs and walls are increasingly being incorporated in urban centers to enhance visual appe... more Green roofs and walls are increasingly being incorporated in urban centers to enhance visual appeal and livability. However, holistic evaluations, that quantify environmental, social as well as financial implications of these measures, are limited, let alone those that use a long term perspective. At the same time, the discussion tends to revolve around the perceived benefits rather than the established or quantified.
This paper, using a holistic evaluation of a project that received Singapore Skyrise Greenery Platinum award in 2011, argues that the strength of the case for adopting or incentivising green strategies in high-rise buildings in the city state is negative from a resource and cost footprint perspective. Assessment methods to quantify social values of the greenery strategies in buildings, such as therapeutic and biophilic benefits, are currently non-existent as the established evaluation methods such as life cycle assessment focus on the production stages rather than the use phase.
While the results reported here stem mainly from the inherited building characteristics, incorporating these greenery strategies at the early design stages and the careful system design can reduce the burden.
Proceedings of 3rd New Zealand Life Cycle Association Conference, Sep 3, 2014
Proceedings of the Sustainable Buildings – Construction, Production and Technologies
Proceedings of the SB13 Singapore: Realising Sustainability in the tropics , Sep 9, 2013
Proceedings iNTA 2012 Conference: Tropics 2050
Proceedings iNTA 2012 Conference: Tropics 2050, 2012
Proceedings of 2nd Computational Design in Engineering Conference, LCA: A business compass for sustainable development
PLEA 2012 Conference: Opportunities, limits and needs towards an environmentally responsive architecture
Proceedings of 2nd New Zealand Life Cycle Assessment Conference, LCA: A business compass for sustainable development
SB07 New Zealand Conference
7th International Conference on Life Cycle Assessment in Agri-Food Sector (Keynote paper)
SB10 New Zealand Conference
12th European Roundtable on Sustainable Consumption and Production
Proceedings Rainwater and Urban Design 2007
Talking and Walking Sustainability, 2nd Conference of New Zealand Society for Sustainability Engineering and Science, Jan 1, 2007
5th Australian Life Cycle Assessment Conference
Proceedings 12th International Sustainable Development Research Conference
Proceedings International Conference on Sustainability Engineering and Science
In New Zealand the building and construction industry makes a significant contribution to the eco... more In New Zealand the building and construction industry makes a significant contribution to the economy. The residential sector which makes up about two thirds of the building and construction industry in New Zealand is unique due to the high rate of home ownership compared to other countries and the rapidly increasing and changing population. The need to improve performance in terms of energy use to reduce the greenhouse gas emissions attributable to the residential sector is now widely recognised. However, there is little evidence about the life cycle performance of NZ houses in terms of energy, cost and environmental impact, as these have not been studied in detail so far. This research focuses on the life cycle performance of common NZ house types in the Auckland region where one third of the New Zealand population live.
Due to the current practice of changing ownership at relatively short periods of about seven years, decisions related to design and construction of NZ houses are based on short-term concerns. However, as buildings last for long periods compared to many other products it is essential to evaluate buildings based on the life cycle performance. Further, sustainable use of building materials, reduction in waste, recycling or reusing the waste materials are not concerns of those who are involved in the construction industry in New Zealand at present.
The aim of this research therefore is to identify and rank the critical factors that influence the life cycle performance of New Zealand houses in the Auckland region. In order to achieve this, common construction types currently used in the construction of NZ houses are identified and an extensive literature survey is carried out to identify the theory and practice of life cycle energy, cost and environmental impact of buildings. This information is then used to generate a computer model, which could be used to examine the current construction practices and design decisions over the useful life of the houses using established methods adapted from the previous work of other researchers but based on the conditions representative of New Zealand practices. The model could be used by designers at the sketch/detail design stages to assess the life cycle performance of their designs.
The results demonstrate that floor, walls and roof represent the bulk of the embodided energy and therefore preliminary energy calculations for these elements could aid in the initial screening of design and construction types appropriate for any situation. The life cycle embodied energy of NZ houses is only around 20% of the total life cycle energy based on the common construction types studied. This is comparable to the figures reported by previous research. Although heavy construction with reduced maintenance requirements over the useful life recorded lower life cycle embodied energy the reduction was not significant.
The results show that of the operating energy, which is the dominant component of the life cycle energy, about a third is for space heating a third for water heating and the balance third is for other uses. The space heating energy requirement could be significantly reduced by increasing the level of insulation. Although increasing the level of insulation could increase the embodied energy, for a standard non-optimised house this alone could reduce the life cycle energy dramatically. This was clearly evident whether or not operating energy other than space heating was included. Although bigger houses and those located in the colder climates use more life cycle energy, use of additional insulation showed a dramatic reduction in life cycle energy and therefore the overall impact. Therefore, reduction in life cycle energy is not reliant on the use of thermal mass, which is less common in New Zealand. Although, additional insulation increased the life cycle cost marginally it could buffer the owner against any sudden increase in energy prices while providing improved comfort and health benefits.
The space heating energy is the only component of total operating energy that depends on design and construction of the building. However, the other operating energy requirements such as water heating and lighting could also be improved at the design stage by the inclusion of measures such as, highly insulated hot water cylinders, solar hot water systems, fuel switching and energy efficient compact fluorescent light bulbs, etc. Whether these would be replaced with identical or similar products when replacement becomes necessary at the end of their useful life by the homeowners would decide the success of such measures.
The results also highlighted the importance of finishes used in NZ houses. Due to shorter replacement cycles, finishes contribute significantly to the total life cycle impact in terms of energy, cost and greenhouse gas emissions. Therefore in terms of life cycle performance not only the mass of the element but also the replacement cycle is equally important.
Life cycle greenhouse gas emissions of NZ houses follow a pattern similar to life cycle energy, as these emissions are mainly due to the energy use. Use of additional insulation could reduce the greenhouse gas emissions significantly. Furniture and domestic appliances although not reliant on the design and construction type contribute significantly to both life cycle energy and greenhouse gas emissions over the useful life of the building due to their relatively short lifespan. Energy used for the operation of appliances was about 20% of the total operating energy over the useful life. Therefore, these items make a significant contribution to the total performance although their replacement requirements and performance are not clearly known. Research into life cycle requirements of furniture, domestic appliances and equipment used in NZ houses and environmental impacts of New Zealand building materials is therefore essential for better understanding of the life cycle performance of NZ houses.
New Zealand Transport Agency Research Report 462, Dec 2011
The aim of the project was to establish the whole-of-life environmental performance of passenger ... more The aim of the project was to establish the whole-of-life environmental performance of passenger and freight movement that uses roads and rail. The performance indicators selected were life cycle energy consumption, life cycle stormwater contamination, and life cycle GHG emissions. This study was based on process assessment and considered material use, transport requirements, on-site machinery use, and fuel use. The impacts of traffic delays and rolling resistance were not considered. The study was undertaken in New Zealand between October 2009 and March 2011 using data for the year beginning July 2007 and ending June 2008.
The results suggest that the environmental impact of pavements can be altered by earthworks (especially in hilly terrains), choice of construction system, and wearing-course construction. Rail emissions can be influenced by the source of the steel rails used. For passenger transport, fuel use is the dominant factor; for freight transport, infrastructure, vehicles and fuel are equally important. However, the use of rail for passenger and freight transport leads to far greater reductions in energy and carbon emissions when
compared against all modes of road transport. The results derived using New Zealand data are significantly different from those using European data. It is therefore essential to use local data in evaluations of transport policies and actions."
MAF Technical Paper No 2011/16 (ISBN 978-0-478-37575-6 (on-line), Mar 2011
Energy and Buildings, 2023
Sustainable Living: the Role of Whole Life Costs and Values, 2007
International studies have shown inefficiency between management of the capital cost for a new co... more International studies have shown inefficiency between management of the capital cost for a new commercial building and its operational costs (typically 10 times larger than capital cost over 25 years). Normally, the capital cost is heavily managed, while the operational cost is poorly known through design-stage modelling assumptions. Post-occupancy empirical assessments of whole-life cost are rare. In New Zealand, sustainable buildings have been encouraged by legislation and government policy, although developers are reluctant to employ measures to ensure greater resource and energy efficiency in new buildings due to the perception that these could be costly. There is, therefore, an inequity in numbers of sustainable buildings developed by the public sector and the private sector. This paper examines the Landcare Research office building in Auckland, which experimented with low-impact design principles, as a case study to gain improved understanding of the annual cost performance in...
12th Annual International Sustainable Development Research Conference, Apr 1, 2006
Energy and Buildings, 2013
ABSTRACT
Journal of Biomechanics, 2008
This study investigated the energy savings and performance of a semi-transparent photovoltaic win... more This study investigated the energy savings and performance of a semi-transparent photovoltaic window in Singapore's tropical climate. Combining photovoltaic technology with windows allows multifunctional performance enhancements as electricity generation, solar heat gain reduction and daylighting contribute to overall energy efficiency. The aim of the study was to improve the design of semi-transparent photovoltaic windows by identifying its total energy savings when installed in various orientations of a building located in the tropics. A standard floor of a building with PV windows was modelled and an annual simulation was performed in EnergyPlus. The simulation was repeated with single and double-glazed windows, instead of the PV windows, under the same conditions. The results indicate that the optimum WWR for east and west facades is 30% while for north and south facades it is 100%. A comparison also shows that semi-transparent BIPV can potentially provide plus-energy benefi...
Life-cycle studies of houses have concentrated on the physical building, excluding the support sy... more Life-cycle studies of houses have concentrated on the physical building, excluding the support systems that are essential for the successful operation of the house, while studies of support systems, such as water supply, usually concentrate on performance improvements and not on the implications of the use of a particular system on the overall residential development. Lifecycle analysis is capable of evaluating competing alternatives based on their environmental performance. This paper examines the impact of water supply systems selection on the environmental performance of individual houses in urban New Zealand using a life-cycle analysis model. The analysis is based on life-cycle energy, environmental impact and cost. Results suggest that the impact of the water supply system on the total performance of the house is negligible when other operating energy uses such as space and water heating are considered. Nevertheless, rain water harvesting systems supplying a household s total w...
Reticulated water supply systems, standard practice in urban areas, suffer from water losses due ... more Reticulated water supply systems, standard practice in urban areas, suffer from water losses due to leaks and pipe bursts, and for satisfactory service need a high level of investment and intervention. Due to growing concern over future water shortages in urban areas, localized measures such as rain tanks are being widely promoted as a more sustainable alternative: they can promote improved water management through behavioural changes, thereby reducing the overall consumption. The two systems, however, vary widely in terms of scale, useful life, and level of service, and it is impossible to assess accurately the relative long-term sustainability performance without a detailed life-cycle analysis. Using the results of a life-cycle study of reticulated supply and rain tanks for urban houses in Auckland, New Zealand, which concentrates purely on the environmental performance, this paper argues that rain tanks may not be the most sustainable option in all situations - while rain tanks a...
The aim of the project was to establish the whole-of-life environmental performance of passenger ... more The aim of the project was to establish the whole-of-life environmental performance of passenger and freight movement that uses roads and rail. The performance indicators selected were life cycle energy consumption, life cycle stormwater contamination, and life cycle GHG emissions. This study was based on process assessment and considered material use, transport requirements, on-site machinery use, and fuel use. The impacts of traffic delays and rolling resistance were not considered. The study was undertaken in New Zealand between October 2009 and March 2011 using data for the year beginning July 2007 and ending June 2008. The results suggest that the environmental impact of pavements can be altered by earthworks (especially in hilly terrains), choice of construction system, and wearing-course construction. Rail emissions can be influenced by the source of the steel rails used. For passenger transport, fuel use is the dominant factor; for freight transport, infrastructure, vehicles...
International Journal of Refrigeration, 2001
The dynamic behaviour of a counter-flow, water-heated evaporator is studied experimentally and nu... more The dynamic behaviour of a counter-flow, water-heated evaporator is studied experimentally and numerically. The frequency distribution of the random oscillations of the mixture-vapour transition point and the superheat temperature at the exit of the evaporator is obtained for steady operation of the system. These oscillations are well correlated. The transition point movement is found to cause fluctuations in the refrigerant temperature over 1 m downstream of its range of motion. Step changes in the refrigerant flow rate and the heating water flow rate demonstrate the non-linear characteristics of the evaporator where the time constants for step increases and step decreases of the same magnitude differ significantly. The distributed model predicts the variation of the superheat temperature and the evaporator pressure following step changes in the inputs with good accuracy.
The International Journal of the Constructed Environment, 2015
The International Journal of Environmental, Cultural, Economic, and Social Sustainability: Annual Review, 2007
Energy and Buildings, 2016