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Alessandro Premier is one of a team of researchers at the School of Architecture, Planning and Design at the University of Auckland. Photo: Supplied<\/p>\nIt was warm and humid on the morning of January 27, 2023, in Auckland, the kind of weather that makes everything feel sticky. Then the rain began. By 5pm, cars were floating down the road in Henderson, entire suburbs were underwater, thousands of people were evacuating their homes, and every fire appliance in the city had been deployed. It would become Auckland\u2019s wettest day in recorded history.<\/p>\n
Aftewards, almost 1200 homes across the city were condemned as posing an \u201cintolerable risk to life\u201d. Some of those houses had been completely destroyed by floodwaters or landslides, some were damaged, and others were completely unscathed but stood at the foot of unstable hillsides considered to be high risk.<\/p>\n
A house comprises 100 tonnes of waste on average \u2013 which meant the 1200 condemned homes were equivalent to a month\u2019s worth of rubbish from the entire city, according to Architecture Now\u2019s Andrew Barrie, a professor of architecture at the University of Auckland.<\/p>\n
\u201cConstruction wood waste is a challenging issue in New Zealand,\u201d says Gary Raftery, a senior lecturer in engineering at the university.<\/p>\n
Most wood waste goes to landfill. At best, it\u2019s chipped and used as fuel for cement manufacturing, or as compost or playground mulch.<\/p>\n
Now, University of Auckland researchers are figuring out how to salvage, assess, recycle and reclassify wood waste as viable building products \u2013 using the 1200 homes condemned by the 2023 floods as a test case.<\/p>\n
The goal: to make it possible for housing materials to go back into housing. \u201cIt\u2019s about activating circular economy processes within our built environment,\u201d says Alessandro Premier, one of a team of researchers at the School of Architecture, Planning and Design working on the project.<\/p>\n
How to recycle a house<\/p>\n
First, researchers must identify and quantify the house\u2019s materials within its walls, floorboards, and structural framing. Premier and colleagues used LiDAR and hand scanners to create virtual models of the condemned houses \u2013 each representing a particular housing style. \u201cSo, we have a repository of digital models that we can use to understand how much material we can effectively reuse, and how we can maximise that\u201d, says Premier.<\/p>\n
Timber-frame detached houses in New Zealand are quite similar, says Premier. Though they come in a variety of typologies, each has common features. \u201cWe have the villas, the bungalows, the state houses \u2013 you\u2019re probably living in one of them.\u201d<\/p>\n
The types of timber might be different \u2013 native timber was widely used up until the 1950s, then radiata pine became the dominant building material from the 1960s onwards. \u201cBut the construction typology in terms of the structural system is relatively similar,\u201d says Premier.<\/p>\n
The idea is that anyone deconstructing a house will eventually be able to look up the housing type and identify where there might be reusable, saleable, or recyclable materials.<\/p>\n
Can old materials be trusted?<\/p>\n
Salvaged timber can\u2019t be immediately reused in the structural framing of a house, says Raftery, because it\u2019s not certified to a certain strength, as new timber is.<\/p>\n
\u201cThere\u2019s a lot of technical challenges with using waste timber,\u201d says Raftery. \u201cThe big issue is quality control. So if there\u2019s no specific data to prove that the material that we\u2019re extracting out can be repurposed in structural applications, then no engineer will really be confident or want to put their own reputation at risk.\u201d<\/p>\n
Alessandro Premier is one of a team of researchers at the School of Architecture, Planning and Design at the University of Auckland. Photo: Supplied<\/p>\n
Raftery and his colleagues are working on changing that. Contractors disassembling Auckland\u2019s condemned houses are providing Raftery with plenty of samples: salvaged timber to test. He plans to identify its mechanical properties: strength, bendiness, toughness, and so on. \u201cThere\u2019s very little knowledge in terms of radiata pine as a species,\u201d says Raftery. \u201cWe don\u2019t really know what mechanical properties we can achieve, because over time timber loses strength \u2013\u00a0some species more than others.\u201d<\/p>\n
If there\u2019s a demand for salvaged timber, and if its strength can be guaranteed, it becomes feasible to do the work of extracting it from homes, removing metal or other contaminants, testing and recertifying it. \u201cThen the motivation is there,\u201d says Raftery.<\/p>\n
The challenge of creating a new market<\/p>\n
Making second-hand materials available for purchase is one thing: making people want to buy them is another.<\/p>\n
While structural components are tricky to reuse because they must be recertified for safety, other components are tricky to reuse because they\u2019re not perfect. Market demand is for brand-new products, says Premier. \u201cThere\u2019s a psychological approach that is related to embracing the ageing of materials,\u201d he says.<\/p>\n
It\u2019s possible for tastes to shift, he says; they already have, at least once. \u201cIn the past, especially when natural materials dominated, architects and clients were pretty much aware that materials were ageing, and they knew that, and they were accepting that,\u201d he says. \u201cNow it\u2019s a little bit more difficult for us to embrace this imperfection because we live in an industrialised society where everything needs to be perfect and new.\u201d<\/p>\n
Some elements of the condemned houses can be used straight away. \u201cThere are some materials, like timber slats, that can be reused for flooring easily\u2014but it will have an old look, and clients must like it,\u201d he says.<\/p>\n
What\u2019s missing is awareness about the importance of reusing materials, and the environmental difference they can make, says Premier. \u201cIt\u2019s very important that the architects, designers, the other stakeholders involved, understand the value,\u201d he says. \u201cIt\u2019s creating a second-hand material market that can be complementary to the standard products commercially available.\u201d<\/p>\n
The opportunity of using second-hand materials<\/p>\n
Reusing and recycling building materials is environmentally meaningful because it locks carbon away for decades, instead of releasing it back into the atmosphere \u2013 which happens when wood is burned, for instance.<\/p>\n
\u201cIn terms of sustainability, every building is designed for 50 years minimum,\u201d says Raftery. \u201cAnd that means that if you\u2019re able to [use] waste timber for another 50 years, it locks that carbon in for five decades again, rather than it being used in mulch in playgrounds or composting or something of that nature \u2013 because that\u2019s not going to lock the carbon in for that same level.\u201d<\/p>\n
It isn\u2019t just flood-damaged homes that could be part of a recycling system. A wide swathe of New Zealand housing is either coming to the end of its life or being updated to accommodate city growth. \u201cThere are a lot of different regions around Auckland that are undergoing sort of a generation change \u2013 Glen Innes, East Tamaki \u2013\u00a0where there\u2019s multi-residential housing being placed instead of older houses that are getting demolished,\u201d says Raftery.<\/p>\n
As our cities grow, it\u2019s possible to use elements of what came before as a trace of the past, says Premier. Housing deemed for demolition could act as a kind of \u201curban mine\u201d that locks in valuable reusable materials \u2013\u00a0preserving heritage all while contributing to sustainability.<\/p>\n","protected":false},"excerpt":{"rendered":"It was warm and humid on the morning of January 27, 2023, in Auckland, the kind of weather…\n","protected":false},"author":2,"featured_media":462854,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22],"tags":[1122,273,111,43,139,69,84870,147,11219,22190],"class_list":["post-462853","post","type-post","status-publish","format-standard","has-post-thumbnail","category-environment","tag-employment","tag-environment","tag-new-zealand","tag-news","tag-newzealand","tag-nz","tag-planetary-solutions","tag-science","tag-sustainable-future","tag-university-of-auckland"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/462853","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=462853"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/462853\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/462854"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=462853"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=462853"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=462853"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}