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Journal Papers by Nalanie Mithraratne

Song, Y., Mithraratne, N., & Zhang, H. (2016). 'Life-time performance of post-disaster temporary housing: A case study in Nanjing', Energy and Buildings, 128: 394-404.

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.

Mithraratne, N. and Frank Low (2015) – ‘Hanging gardens in cities: potential benefits as a retro-fit’ in ‘The International Journal of Constructed Environment’ vol. 6(3), August 2015, pp.15-23.

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.

Ng P. K. and N. Mithraratne (2014) – ‘Lifetime performance of semi-transparent building-integrated photovoltaic (BIPV) glazing systems in the tropics, Renewable & Sustainable Energy Reviews, 31(0): 736-745.

Poh Khai Ng, Nalanie Mithraratne, Harn Wei Kua (2013) - 'Energy analysis of semi-transparent BIPV in Singapore buildings', Energy and Buildings, 66:274-281.

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.

Roof-top wind turbines for microgeneration in urban houses in New Zealand

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.

Conventional and alternative water supply systems: a life cycle study

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 ...

Water supply infrastructure and settlement patterns

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

Due partly to the government incentives introduced under the sky rise greenery initiative, green ... more Due partly to the government incentives introduced under the sky rise greenery initiative, green roofs are common in the tropical Singapore compared with the other eco-roof types. With limited land and natural resources within national boundaries Singapore is unique, as most system components for green roofs have to be imported from elsewhere while waste has to be incinerated. The main focus of green roof studies in this unique Singapore setting so far has been the in-use performance benefits in terms of cost, energy and water savings without considering the life time performance. However, resource costs as well as benefits need to be considered in the decision to promote any strategy. This paper discusses preliminary results from a study that aims to develop a life cycle carbon footprint based decision framework for selecting eco-roof strategies. The results indicate that the carbon footprint of green roofs depends on the construction details and system components used. The end-of-life waste disposal contributes significantly to the carbon footprint, even with system expansion to include avoided electricity generation as a result of green roof waste incineration, main method used for waste management in Singapore.

Proceedings of the Sustainable Buildings – Construction, Production and Technologies

Sustainable buildings seek not only to increase energy efficiency, but also to adopt renewable te... more Sustainable buildings seek not only to increase energy efficiency, but also to adopt renewable technologies in its design. As such, semi-transparent building-integrated photovoltaic (BIPV) is gaining popularity among architects and building designers, mainly due to its ability to contribute towards a zero-(or even plus) energy building. Semi-transparent BIPV windows not only generate electricity but also allow daylight into the building and reduce the need for artificial lighting. As with other window façade elements, their incorporation will however, increase the cooling load due to solar heat gains. This is even more pertinent in tropical climates where temperatures are high all year round. This paper examines the life cycle environmental performance of a commercially available doubleglazed semi-transparent BIPV module for window application under the tropical conditions of Singapore. Energy simulations were performed in EnergyPlus with measured data on optical, thermal and electrical properties of the semi-transparent BIPV glazing in tropical conditions. Subsequently, a life cycle assessment was conducted to determine the long term performance in terms of energy and carbon emissions.

Proceedings of the SB13 Singapore: Realising Sustainability in the tropics , Sep 9, 2013

Proceedings iNTA 2012 Conference: Tropics 2050

Blue and green are two eco-roof options commonly used to improve energy and storm water performan... more Blue and green are two eco-roof options commonly used to improve energy and storm water performance of buildings in urban centres. This paper presents the results of a study investigating whether blue roof is environmentally more preferable to green roof in Singapore. It discusses the thermal performance, and life cycle costs of blue roofs and green roofs in Singapore. A shallow roof pond on a glazed roof is compared with both extensive and intensive green roofs.

Proceedings iNTA 2012 Conference: Tropics 2050, 2012

Semi-transparent Building-Integrated Photovoltaic (BIPV) windows are gaining popularity among arc... more Semi-transparent Building-Integrated Photovoltaic (BIPV) windows are gaining popularity among architects and building developers due to its potential to enhance a building's energy efficiency. Semitransparent BIPV not only generates electricity and enhances the potential use of daylight but also decreases cooling demand through reducing unwanted solar gains. This complex behaviour of semi-transparent BIPV means that designers require performance-based tools that facilitate its integration in buildings. This paper proposes a framework for selection and application of photovoltaic windows in tropical Singapore. The paper discusses the process of deriving this framework that aims to provide a simplified approach for building designers that optimizes the BIPV integration and facilitates the wider uptake in building applications.

Proceedings of 2nd Computational Design in Engineering Conference, LCA: A business compass for sustainable development

Keywords: green roof, blue roof, white roof, life cycle assessment, carbon footprint

PLEA 2012 Conference: Opportunities, limits and needs towards an environmentally responsive architecture

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 benefits to tropical buildings instead of decreasing its energy efficiency.

Proceedings of 2nd New Zealand Life Cycle Assessment Conference, LCA: A business compass for sustainable development

Transport facilitates socio-economic activities by providing a direct link between various partie... more Transport facilitates socio-economic activities by providing a direct link between various parties and affects all aspects of modern life either directly or indirectly. Most discussions on sustainability concentrate on the transport mode and fuel use irrespective of whether it is passenger or freight transport that is being considered. This could be regarded reasonable as fuel use for land transport is significant in the annual energy expenditure of most countries and has been steadily increasing. While the UN reported a 12% increase in global CO 2 emissions due to transport between 2000 and 2005, 19% of New Zealand's total greenhouse gas (GHG) emissions in 2009 were also due to fuel combustion in the transport sector . Given the threat of climate change and the uncertainty surrounding oil supply, the current practices will not be economically or environmentally sustainable.

SB07 New Zealand Conference

Building assessment schemes provide an evaluation of the resource use in the construction industr... more Building assessment schemes provide an evaluation of the resource use in the construction industry. Most readily available assessment schemes are neither in a format easily understood by those involved in the construction industry nor provide results that promote more sustainable practices. Models developed with location-specific practices have been criticised for their inability to be used for global comparisons of sustainability of activities. The use of overseas data for environmental impact assessment, however, is not always representative of the implications for a given location and is therefore of limited value.

Song, Y., Mithraratne, N., & Zhang, H. (2016). 'Life-time performance of post-disaster temporary housing: A case study in Nanjing', Energy and Buildings, 128: 394-404.

Poh Khai Ng, Nalanie Mithraratne, Harn Wei Kua (2013) - 'Energy analysis of semi-transparent BIPV in Singapore buildings', Energy and Buildings, 66:274-281.

Roof-top wind turbines for microgeneration in urban houses in New Zealand

Conventional and alternative water supply systems: a life cycle study

Water supply infrastructure and settlement patterns

Paper presented at the Construction & Deconstruction: Building Today Saving Tomorrow Conference

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

Keywords: green roof, blue roof, white roof, life cycle assessment, carbon footprint

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)

The New Zealand government has initiated a strategy on greenhouse gas (GHG) footprinting for the ... more The New Zealand government has initiated a strategy on greenhouse gas (GHG) footprinting for the landbased primary sectors (under the Sustainable Land Management and Climate Change Plan of Action). A key part of this strategy is development of sector-specific approaches to GHG footprinting and management, and thirteen primary agricultural sectors have participated in projects to date. This paper focuses on the carbon footprinting studies undertaken for apples and kiwifruit. For both studies, the ISO 14040 and 14044 standards were followed for the analysis, as well as the PAS 2050 specification. Examples of issues that have arisen include: variability between different orchards, yield variability between years, data variability, carbon storage in soils, and allocation between different grades of fruit. The relative importance of these aspects in relation to determining the carbon footprint of apples and kiwifruit is discussed, and the implications for carbon management on a sector-basis are explored. options, and work towards development of strategies for reducing the carbon footprint (CF) on a sector-wide basis.

SB10 New Zealand Conference

12th European Roundtable on Sustainable Consumption and Production

Quantitative carbon labelling of products is currently fashionable. In the UK, the British Standa... more Quantitative carbon labelling of products is currently fashionable. In the UK, the British Standards Institution, sponsored by the Carbon Trust and Department for Environment, Food and Rural Aff airs (DEFRA), is producing a Publicly Available Specifi cation (PAS 2050) for assessing the life cycle greenhouse gas emissions of good and services. It is intended that "the PAS method may be used for a variety of formal and informal processes for improving and communicating the GHG performance of products and services. This includes processes for product improvement, Green Supply Chain Management, sustainable procurement, Environmental Management Systems, Environmental Product Declarations such as labels, consumer awareness campaigns and business reporting" (BSI, 2008). The Carbon Trust is also working with a number of other organisations to produce two further documents that will accompany the PAS: a Reductions Framework (PERF) and a Code of Good Practice. It has also devised a quantitative carbon label that is being trialled by a number of companies using the draft PAS methodology.

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

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.

Proceedings 12th International Sustainable Development Research Conference

Proceedings International Conference on Sustainability Engineering and Science

At present New Zealand is divided into three climate zones in terms of the Energy Efficiency Buil... more At present New Zealand is divided into three climate zones in terms of the Energy Efficiency Building Code requirements. Light timber framed construction type and the 'mass construction type' commonly used in the Auckland region do not satisfy the requirements for the colder climate region. In order to determine the total impact a particular building makes on the environment, operating as well as construction requirements over the useful life of such buildings should be considered. However, since buildings last for a long period compared to building materials and equipment -around 100 years -the data required for an analysis of life cycle energy and cost are numerous and analysis would be tedious and time consuming and often not practical for a practicing architect. This paper describes a method that has been developed at the University of Auckland for a detailed life cycle analysis of an individual house based on the embodied and operating energy requirements and life cycle cost over the useful life of the building with funding from the Public Good Science Fund of the Foundation for Research, Science and Technology of New Zealand. This design tool allows a building to be assessed at the design stage, so that various design options and strategies can be compared with one another and also to quantify the environmental impact of New Zealand house designs over their useful lifetime. Although the model is based on the generic construction types that are currently being used, it has been designed as an expert system so that updating the model database can be done with relative ease. The rest of the paper discusses the use of this tool to explore the optimum specification for house construction for the different climate regions of New Zealand in terms of life cycle energy and cost.

Dwelling, In ‘Living within a fair share ecological footprint’, Brenda Vale and Robert Vale (ed.), London: Thames and Hudson, March 2013, pp.84-95

Sustainable Living: The role of whole life costs and values

The contribution of water supply systems to climate change, In ‘Green CITYnomics: The Urban War against Climate Change’, Kenny Tang (ed.), Sheffield: Greenleaf Publishing, October 2009

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."

Greenhalgh, S., Mithraratne, N., Sinclair, R., Smith, A., McConachy, E. and Barber, A. - GHG Product Accounting Guidelines for the Wine Industry, MAF Technical Paper 2011/16, New Zealand, March 2011

MAF Technical Paper No 2011/16 (ISBN 978-0-478-37575-6 (on-line), Mar 2011

Hume, A., Mithraratne, N., Barber, A., Snelling, C. and East, A. – Greenhouse gas Footprinting and Berryfruit Production: Methodology and scoping study, Landcare Research Report LC0910/048, for Blackcurrants NZ Ltd. and the New Zealand Boysenberry Council Ltd, New Zealand, November 2009

Mithraratne, N., McLaren, S. J. and Barber, A. – Carbon Footprinting for the Kiwifruit supply chain: Report on methodology and scoping study, Landcare Research Report LC0708/156, for Ministry for Agriculture and Forestry, New Zealand, August 2008

Research on influences of wall design on embodied and operating energy consumption: A case study of temporary building in China

Energy and Buildings, 2023

Research on influences of wall design on embodied and operating energy consumption: A case study of temporary building in China

Energy and Buildings

The contribution of water supply systems to climate change

Life cycle performance of an average New Zealand house

Sustainable Living: the Role of Whole Life Costs and Values, 2007

Whole-Life Cost of Development Decisions : A Case Study

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...

Transport facilitates socioeconomic activities by providing a direct link between various parties... more Transport facilitates socioeconomic activities by providing a direct link between various parties and affects all aspects of modern life either directly or indirectly. Most discussions on sustainability concentrate on the transport mode and fuel use irrespective of whether it is passenger or freight transport that is being considered. This could be regarded reasonable as fuel use for land transport is significant in the annual energy expenditure of most countries and has been steadily increasing. While the UN reported a 12% increase in global CO 2 emissions due to transport between 2000 and 2005, 19% of New Zealand's total greenhouse gas (GHG) emissions in 2009 were also due to fuel combustion in the transport sector [1, 2]. Given the threat of climate change and the uncertainty surrounding oil supply, the current practices will not be economically or environmentally sustainable. Once constructed, the pavements on which land vehicles travel lock in resources (land and materials) for a very long time. International studies have estimated that up to 65% of total energy and emissions associated with passenger and freight transport result from indirect sources such as transport infrastructure, vehicle manufacture and fuel extraction [3, 4]. GHG emissions due to a kilometer length of a single pavement lane could vary from 80 to 500tCO 2 e over a 50 year period, with energy losses through tyre-pavement contact (known as rolling resistance), traffic delays, construction materials used, and material transportation being the main factors determining lifetime emissions [5]. Therefore the decisions on how pavements are constructed and maintained could be of utmost importance. New Zealand studies on pavement construction so far have been either limited to a single phase of pavement life (construction) [6] or to the use of alternative construction materials [7, 8].

Life-cycle resource efficiency of conventional and alternative water supply systems

12th Annual International Sustainable Development Research Conference, Apr 1, 2006

Energy analysis of semi-transparent BIPV in Singapore buildings

Energy and Buildings, 2013

ABSTRACT

1D and 3D Blood Flow Modelling for Patient Specific Cerebral Vasculature and Aneurysm

Journal of Biomechanics, 2008

Semi-Transparent Building-Integrated Photovoltaic Windows: Potential Energy Savings of Office Buildings in Tropical Singapore

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...

An experimental and numerical study of the dynamic behaviour of a counter-flow evaporator

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.

Hanging Gardens in Cities

The International Journal of the Constructed Environment, 2015

Water Supply Infrastructure & Settlement Patterns

The International Journal of Environmental, Cultural, Economic, and Social Sustainability: Annual Review, 2007

Life-time performance of post-disaster temporary housing: A case study in Nanjing

Energy and Buildings, 2016

Measures to minimise construction waste

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Hanging Gardens in Cities: Potential Benefits as a Retro-fit

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