title: Preliminary materials flow analysis for Aotearoa New Zealand’s building construction sector

authors: Nelson, Jacob Martin Bruton

abstract: This report describes the methodology used to produce a database of construction material flow in Aotearoa New Zealand and summarises the contents of that database. The database was produced as part of a wider research programme, Āmiomio Aotearoa, which aims to help New Zealand transition to a circular economy.
In order to assess the materials flowing through the building construction sector, the research focussed on residential dwellings, which constituted a larger proportion of the sector than commercial construction in terms of number of new buildings, floor area of new buildings, and the value of new buildings.¹ The building envelope, including the foundations, structure, cladding, roofing, insulation, and lining of the structure, was examined as it accounted for the largest portion of materials in each dwelling. The data was assessed through the four key stages of material flow: material input, construction, demolition and material output.
In terms of material input, timber was the most thoroughly documented material used in construction. An estimated 1.98 million tonnes of timber and timber-based products were supplied to the New Zealand market through local production and imports in 2021. Furthermore, it was estimated that roughly 10.4 million tonnes of ready-mix concrete were used in 2021. Meanwhile, approximately 850 thousand tonnes of steel are consumed within New Zealand annually. However, the amount of concrete and steel that is consumed in the building construction sector specifically is unknown.
An estimation of the materials used in the envelope of residential buildings, based on consent data, New Zealand building reports and standard residential building designs, suggested that concrete and masonry were the most used materials in construction, followed by timber, plasterboard, and metals. In total, it was estimated that 2.07 million tonnes of material were consumed in 2021 in the residential construction sector. A case study using purchase order data validated this estimation, showing that the key materials studied were all of the same magnitude.
Data on the number of demolitions in New Zealand was very limited, largely because consents are not required for the demolition of houses under three stories.² However, using some assumptions around census and new building consent data, it was calculated that roughly 5,488 residential demolitions occur annually in the current state of the industry.
Waste from the building construction sector was studied in terms of the whole construction and demolition sector, as well as the expected waste from residential construction and demolition. It was expected that the total construction and demolition sector produces roughly 3.6 million tonnes of waste annually, with an additional 1.4 million tonnes of material from construction being recovered. However, the study found that the differentiation between infrastructure, commercial, and residential construction waste was largely unmeasured.
The residential construction sector was estimated to produce 347 thousand tonnes of waste in 2021, of which 267 thousand tonnes was expected to go to landfill. This waste was produced from: The building envelope (147 thousand tonnes); the rest of the construction (49 thousand tonnes); alterations of residential buildings (25 thousand tonnes); and demolition of residential structures (126 thousand tonnes). Estimations indicated that concrete was the largest contributor to waste, followed by plasterboard and then timber.
The report also includes comments from industry experts to further portray the picture of the current state of material flow in the construction and demolition sector, and the issues faced with the production of waste.
Overall, this report is a first attempt to provide a picture of materials flowing through New Zealand’s building construction sector. Due to limitations of data currently being collected within NZ and available to the team within the timeframe of the project, the report has focused on estimating the materials used in the shell of residential buildings; detailing where and how materials are being recycled was out of scope. Contradiction with perceived state of the art recycling is likely due, at least in part, to assumptions that because materials can be recycled, they are indeed being recycled (as per our domestic recycle bins). Despite the data limitations, this report and associated database usefully indicate prime waste materials for incorporation into novel building materials and therefore provide insight to support the direction of future research. The report and associated database also provide a foundation which could be used to support further enterprise to provide a clearer picture of materials flows within the building construction sector.

text: Preliminary materials flow analysis for Aotearoa New Zealand’s building construction sector This report describes the methodology used to produce a database of construction material flow in Aotearoa New Zealand and summarises the contents of that database. The database was produced as part of a wider research programme, Āmiomio Aotearoa, which aims to help New Zealand transition to a circular economy.
In order to assess the materials flowing through the building construction sector, the research focussed on residential dwellings, which constituted a larger proportion of the sector than commercial construction in terms of number of new buildings, floor area of new buildings, and the value of new buildings.¹ The building envelope, including the foundations, structure, cladding, roofing, insulation, and lining of the structure, was examined as it accounted for the largest portion of materials in each dwelling. The data was assessed through the four key stages of material flow: material input, construction, demolition and material output.
In terms of material input, timber was the most thoroughly documented material used in construction. An estimated 1.98 million tonnes of timber and timber-based products were supplied to the New Zealand market through local production and imports in 2021. Furthermore, it was estimated that roughly 10.4 million tonnes of ready-mix concrete were used in 2021. Meanwhile, approximately 850 thousand tonnes of steel are consumed within New Zealand annually. However, the amount of concrete and steel that is consumed in the building construction sector specifically is unknown.
An estimation of the materials used in the envelope of residential buildings, based on consent data, New Zealand building reports and standard residential building designs, suggested that concrete and masonry were the most used materials in construction, followed by timber, plasterboard, and metals. In total, it was estimated that 2.07 million tonnes of material were consumed in 2021 in the residential construction sector. A case study using purchase order data validated this estimation, showing that the key materials studied were all of the same magnitude.
Data on the number of demolitions in New Zealand was very limited, largely because consents are not required for the demolition of houses under three stories.² However, using some assumptions around census and new building consent data, it was calculated that roughly 5,488 residential demolitions occur annually in the current state of the industry.
Waste from the building construction sector was studied in terms of the whole construction and demolition sector, as well as the expected waste from residential construction and demolition. It was expected that the total construction and demolition sector produces roughly 3.6 million tonnes of waste annually, with an additional 1.4 million tonnes of material from construction being recovered. However, the study found that the differentiation between infrastructure, commercial, and residential construction waste was largely unmeasured.
The residential construction sector was estimated to produce 347 thousand tonnes of waste in 2021, of which 267 thousand tonnes was expected to go to landfill. This waste was produced from: The building envelope (147 thousand tonnes); the rest of the construction (49 thousand tonnes); alterations of residential buildings (25 thousand tonnes); and demolition of residential structures (126 thousand tonnes). Estimations indicated that concrete was the largest contributor to waste, followed by plasterboard and then timber.
The report also includes comments from industry experts to further portray the picture of the current state of material flow in the construction and demolition sector, and the issues faced with the production of waste.
Overall, this report is a first attempt to provide a picture of materials flowing through New Zealand’s building construction sector. Due to limitations of data currently being collected within NZ and available to the team within the timeframe of the project, the report has focused on estimating the materials used in the shell of residential buildings; detailing where and how materials are being recycled was out of scope. Contradiction with perceived state of the art recycling is likely due, at least in part, to assumptions that because materials can be recycled, they are indeed being recycled (as per our domestic recycle bins). Despite the data limitations, this report and associated database usefully indicate prime waste materials for incorporation into novel building materials and therefore provide insight to support the direction of future research. The report and associated database also provide a foundation which could be used to support further enterprise to provide a clearer picture of materials flows within the building construction sector.

year: 2022

title: Triangular Bézier sub-surfaces on a triangular Bézier surface

authors: Chen, Wenyu

subjects: composition

abstract: This paper considers the problem of computing the Bézier representation for a triangular sub-patch on a triangular Bézier surface. The triangular sub-patch is defined as a composition of the triangular surface and a domain surface that is also a triangular Bézier patch. Based on de Casteljau recursions and shifting operators, previous methods express the control points of the triangular sub-patch as linear combinations of the construction points that are constructed from the control points of the triangular Bézier surface. The construction points contain too many redundancies. This paper derives a simple explicit formula that computes the composite triangular sub-patch in terms of the blossoming points that correspond to distinct construction points and then an efficient algorithm is presented to calculate the control points of the sub-patch.

text: Triangular Bézier sub-surfaces on a triangular Bézier surface This paper considers the problem of computing the Bézier representation for a triangular sub-patch on a triangular Bézier surface. The triangular sub-patch is defined as a composition of the triangular surface and a domain surface that is also a triangular Bézier patch. Based on de Casteljau recursions and shifting operators, previous methods express the control points of the triangular sub-patch as linear combinations of the construction points that are constructed from the control points of the triangular Bézier surface. The construction points contain too many redundancies. This paper derives a simple explicit formula that computes the composite triangular sub-patch in terms of the blossoming points that correspond to distinct construction points and then an efficient algorithm is presented to calculate the control points of the sub-patch.

year: 2011

title: Enabling conditions for professional development of te reo Māori teachers

authors: Franken, Margaret

subjects: Māori language teachers

abstract: The paper outlines a professional development programme for secondary school teachers of te reo Māori (under the auspices of Te Hiringa i te Mahara) conducted by a language teacher educator and an expert in Māori bilingualism and biliteracy. While the principles underpinning the programme reflect a strong task-based
orientation, the programme approached development needs for the teachers from the point of view of understanding “enabling conditions” (Franken, Rau, Ngata & Parata, n.d.) for effective language learning and teaching (see also Ellis, 2005),
rather than understanding task based learning and teaching per se. The programme drew on the current practices of the teachers and made use of epistemology of Māori language and Māori language learning. The paper presents observations from monitoring data collected during the programme supporting the claim that such an approach to the professional development of language teachers promotes a strong knowledge base and pedagogical reasoning skills (Richards, 1998), and in particular for te reo Māori teachers, fosters a sense of their own professional identity.

text: Enabling conditions for professional development of te reo Māori teachers The paper outlines a professional development programme for secondary school teachers of te reo Māori (under the auspices of Te Hiringa i te Mahara) conducted by a language teacher educator and an expert in Māori bilingualism and biliteracy. While the principles underpinning the programme reflect a strong task-based
orientation, the programme approached development needs for the teachers from the point of view of understanding “enabling conditions” (Franken, Rau, Ngata & Parata, n.d.) for effective language learning and teaching (see also Ellis, 2005),
rather than understanding task based learning and teaching per se. The programme drew on the current practices of the teachers and made use of epistemology of Māori language and Māori language learning. The paper presents observations from monitoring data collected during the programme supporting the claim that such an approach to the professional development of language teachers promotes a strong knowledge base and pedagogical reasoning skills (Richards, 1998), and in particular for te reo Māori teachers, fosters a sense of their own professional identity.

year: 2009