Parliamentary Commissioner for the Environment Simon Upton sets out the case for protecting green space against the backdrop of 'irreversible' densification of NZ cities

As population growth and urban planning rules drive "irreversible" densification in New Zealand's cities we must protect urban green space, a form of infrastructure just as important as pipes and roads, the Parliamentary Commissioner for the Environment Simon Upton argues.

Upton says building high-rise apartments instead of low-rise infill development such as townhouses can help with this as it uses urban land more efficiently, reducing pressure to develop green spaces elsewhere in cities. He also suggests more attention could be given to counteracting the loss of private yards and gardens by improving public green spaces.

Meanwhile, Upton says the Medium Density Residential Standards (MDRS), allowing the building of up to three homes of up to three storeys on most residentially zoned sites in Auckland, Hamilton, Tauranga, Wellington and Christchurch without the need for a resource consent following bipartisan agreement between the Labour and National parties, will place "particular pressure" on private residential green space in the years ahead.

This is all detailed in a report issued by Upton on Thursday; Are we building harder, hotter cities? The vital importance of urban green spaces.

"Some may ask whether, in the midst of burgeoning demand for housing, the provision and protection of urban green space is really something that warrants attention. After all, every square metre of potentially developable land that is set aside as parks, yards, gardens or lawns cannot be used for housing," Upton says.

"It is important to respond to that question because the changes we are making to the shape and form of our cities are largely irreversible. If they are not executed skillfully, we risk building less liveable environments that we will have to live with forever. There are at least three particular concerns."

His first concern is what the loss of green space could mean for the health and wellbeing of city dwellers.

"Cities are frenetic, busy and often noisy places to live. Having places nearby to exercise or socialise, or simply to escape the day-to-day clamour of city life, plays a vital role in promoting good mental and physical health. The importance of urban green space was highlighted during recent Covid-19 lockdowns when movement restrictions meant access to nearby parks and reserves became a lifeline for many people," says Upton.

Extreme weather event reminder

His second concern centres around the environmental services green space provides.

"If we had forgotten the value of these services, recent extreme weather events have put them right back at the centre of everyone’s attention. In the 18 months it has taken to prepare this report a series of major storm events have left destruction in their wake across New Zealand. Daily and monthly rainfall records have been swept away in, for example, Nelson and Auckland. Ageing stormwater systems have been overwhelmed, flooding houses and businesses and leaving their owners with costly clean ups."

"These events have demonstrated the perils of creating large, hardened and impermeable surfaces that simply cannot cope with the sort of precipitation a warmer atmosphere is delivering. One response might be simply to harden up further - even more gigantic stormwater management structures and stouter defences of steep ground and coastal margins. But even if that worked, climate change is bringing temperature stress in its wake. Heat wave crises have not yet been acutely felt in New Zealand, but there is every reason to believe they will be - and when they are, a cityscape of concrete, asphalt and black roofs will serve only to amplify the discomfort of city dwellers and, in some cases, put lives at risk," Upton says.

"It is an irony that in an age of rising environmental concern, more people live in urban settings cut off from the natural environment than ever before. But urban dwellers are as dependent on the environment as they ever were. Green spaces continue to provide a range of vital services, including temperature regulation, stormwater management, air filtration, carbon sequestration and habitat provision."

Upton's third concern relates to the amenity or "placemaking" benefits urban green space provides.

"While visual amenity means different things to different people, the value proposition around denser urban living is generally considered to be improved by the presence of trees and vegetation. The value of these services - recreational, environmental and visual - is not constant in time," he says.

'Think very carefully about hasty development decisions'

Looking ahead Upton says the ongoing move to more densely populated cities and the emerging impacts of climate change are likely to make urban parks, reserves, gardens, vegetation and street trees more valuable.

"The difficulty of re-establishing green space once lost should cause us to think very carefully about hasty development decisions that future generations may live to regret," Upton says.

"I find myself increasingly irritated by the scores of documents that emerge from central and local government talking tritely about ‘quality urban environments’ in which people can ‘live, work and play.’ These soothing green noises are too often offered as a substitute for hard analysis. A determination to increase housing supply through denser, infill housing within the pre-existing boundaries of cities involves a necessary trade-off with the amount of private urban green space that will remain. The extent of that trade-off should be explicit and open to debate."

"This report does not seek to judge what the extent of that trade-off should be. Neither does it spend a lot of time on cultural, health and amenity values. While important, these are widely commented on. The focus, rather, is on the underlying environmental services that are too often taken for granted. I hope that this report will improve our understanding of how and where green space is changing, for what reasons, and what the likely consequences of those changes might be," says Upton.

"Importantly, it looks at the totality of green space, public and private, and attempts to signal the environmental services and values that need to be monitored and provided for as urban form and density evolve."

Government policies 'pose considerable risks for urban green space'

The report says between 1980 and 2016 green space per person fell by at least 30% in Auckland, and at least 20% in Hamilton with nearly all of this loss occurring on private residential land. Upton says two main factors have driven this trend; firstly infill development seeing the conversion of yards and sections into houses and driveways in existing urban areas, and secondly a shift towards larger houses on smaller sections in new subdivisions.

Two recent central government policy initiatives designed to encourage additional housing supply through intensification in major cities are now set to intensify this.

"One, the National Policy Statement on Urban Development (NPS-UD), will provide additional impetus for development ‘upwards’ in areas close to existing centres and public transport nodes. The other, the Medium Density Residential Standards (MDRS), will allow development ‘inwards’ across significant swathes of the urban area," Upton says.

"At the same time, the National Policy Statement for Highly Productive Land and the wetlands provisions in the National Policy Statement for Freshwater Management will further support housing intensification over development outwards."

First published in 2020, the NPS-UD requires Tier 1 councils, (Auckland, Tauranga, Hamilton, Wellington and Christchurch), to enable building heights of at least six storeys within metropolitan centre zones and a “walkable catchment” of existing and planned rapid transit stops, the edge of city centre zones, and the edge of metropolitan centre zones.

As Upton puts it, both the NPS-UD and the MDRS are responses to the rapid increase in house prices between 2013 and 2021 and are intended to improve housing affordability by requiring councils to increase the supply of land zoned for denser forms of development, primarily in already built-up areas. If reducing transport emissions and congestion is the goal, he says both the NPS-UD and MDRS are almost certainly preferable to development outwards.

"That said, both policies also pose considerable risks for urban green space. The MDRS in particular, with its focus on promoting medium-density infill development across broad swathes of our cities, has the potential to accelerate the ongoing reduction in private green space ... with little consideration apparently being given to how improved public green space could help to compensate for that," says Upton.

Because they apply to all residentially zoned areas, Upton says the MDRS are potentially more consequential, both for housing supply and green space, than the NPS-UD requirements. However, the actual impact will depend on market dynamics as well as the extent to which councils seek to carve out particular areas from up-zoning on the basis of "qualifying matters" identified in the Resource Management (Enabling Housing Supply and Other Matters) Amendment Act.

"The proposed plan changes notified by some councils, Auckland Council and Hamilton City Council, for example, identify concerns about infrastructure capacity and the loss of special character as a reason to exclude significant areas from up-zoning. It remains to be seen, as of October 2022, whether those decisions survive the scrutiny of the hearing processes that will follow," Upton says.

He also notes Auckland Council’s response to the MDRS explicitly recognises the cooling function trees provide, with its "Plan Change 78" to the Auckland Unitary Plan containing an objective requiring development to “reduce the urban heat island effects of development and respond to climate change, by providing deep soil areas that enable the growth of canopy trees.”

A recent episode of interest.co.nz's Of Interest podcast focused on the Medium Density Residential Standards in detail, which councils in the five biggest cities are now moving to adopt.

Apartments vs townhouses

Upton suggests outcomes from the NPS-UD and MDRS for green space are likely to be quite different.

"While multi-storey apartment buildings and low-rise terraced housing both tend to consume much of the green space available at individual sites, apartments do so while providing many more dwellings. All else being equal, that means less pressure to develop green space elsewhere in the city, but more recreational demand on pre-existing nearby parks."

"In the long term, the green space implications of the Government’s push for intensification will depend on the relative uptake of the NPS-UD and MDRS," he says. "Council decisions will be an important factor in this, but so will market dynamics."

He cites a number of reasons why the townhouses and terraced housing promoted by the MDRS might emerge as a market winner.

"Most obviously, no resource consent process - or public notification - is required to build them. For developers, that translates into time and cost savings. Townhouses are also less technically demanding and capital intensive to build, and there is very likely a smaller pool of developers with the resources to attempt larger, more complex multi-storey apartments," says Upton.

"Furthermore, townhouses and terraced houses typically come without body corporate arrangements - something which, anecdotally at least, can be a barrier to demand for apartment living."

The report uses examples from Auckland suburbs to highlight a move to smaller sections and larger houses. It says an average new dwelling in Papatoetoe in the 1970s had a footprint of 190 square metres and was situated on an 800 square metre parcel of land. By the 2010s, suburbs like Flat Bush had dwellings with an average footprint of 210 metres on sections of only 420 square metres.

"While that still leaves a considerable amount of space for lawns, gardens and trees to be established, in reality, sealed driveways, paths and patio areas are often preferred."

'Green space is infrastructure too'

Upton says the Government has recognised housing development enabled by the NPS-UD and MDRS will make increased claims on a range of existing infrastructure by requiring councils to provide enough development infrastructure to service expected growth, via the NPS-UD, and allocating funding, via the Housing Acceleration Fund, to help councils do that.

"No such consideration appears to have been made for public green space. That is surprising given that the aim of both policies is allegedly to improve urban wellbeing, both now and in the future, and to do so in a way that is resilient in the face of expected climate change."

Upton argues for what he describes as natural assets such as urban forests, wetlands, riparian strips and other types of green space to be considered as infrastructure.

He makes the point that most definitions of infrastructure include some reference to its built or human-made character. The 2011 National Infrastructure Plan, for example, defines infrastructure as “the fixed, long-lived structures that facilitate the production of goods and services and underpin many aspects of quality of life.”

"Definitions like this exclude natural assets such as urban forests, wetlands, riparian strips or other types of green space. On the one hand, that is sensible. Natural assets are fundamentally different to built assets: their creation requires decades to hundreds, if not thousands of years, and once established they do not depreciate in the way that built assets do," says Upton.

"On the other hand, natural assets provide many of the same services that built assets do. The United States Congress, for example, recently acknowledged the role that nature plays in filtering and absorbing stormwater."

"While debating naming conventions may seem peripheral, what is - and is not - classed as infrastructure has practical implications for funding sources and the suite of regulatory tools that are available to councils."

Upton points out the NPS-UD distinguishes between “development infrastructure” such as the three waters and roading infrastructure required to serve new developments, and “additional infrastructure” being things like open space and community facilities.

"Councils must be 'satisfied' that the latter 'is likely to be available' but are required to provide the former," he says. "There is no statutory requirement for territorial authorities to plan for or provide public green space in New Zealand."

The report highlights that building consent data shows the share of townhouses, units and flats in all new residential builds in NZ cities increased to about 55% in 2022 from about 10% in 2011. Over the same time period, the share of apartments being built remained roughly steady at about 10%, while the share of standalone houses fell from about 75% to about 30%.

'At the very time that urban green space is likely to be in greater demand, there is likely to be less of it available'

Looking at Statistics NZ's population forecasts for NZ cities, Upton says the populations of Auckland, Hamilton, and Tauranga are forecast to all grow by more than a third by 2043, or by 553,000, 57,900 and 49,300 people, respectively. Christchurch and Greater Wellington are also expected to grow over the same period, but more slowly, by 70,000 and 65,700 people, respectively.

Factoring in a forecast decline in household occupancy rates, the report says by 2043 an extra 208,100 households are expected to be needed in Auckland, 22,000 in Hamilton and 20,700 in Tauranga. This equates to around a 37% increase for all three cities from 2018 levels. Christchurch, the report says, can expect 28,400 more households by 2043, or about a 19% increase, with a 20% increase expected in Wellington City and the Hutt Valley, while Porirua City can expect something around 25%.

"As our cities grow, they will also increasingly feel the effects of climate change. That will mean increased heat and more frequent extreme rainfall events. Parks, yards, vegetated berms and trees can help to mitigate the impacts of both, but only to the extent that they remain healthy and functioning in what is likely to be a more challenging environment," says Upton.

"Climate change will make the environmental services provided by green space more important in future. At the same time, the ongoing shift towards townhouse and apartment living – and associated reduction in the size of sections and yards – will make the recreational offering provided by public parks and reserves more sought after. The reality is that, at the very time that urban green space is likely to be in greater demand, there is likely to be less of it available."

The report says currently about 30% of Auckland’s urban area is private green space. But expected population growth and intensification have the potential to reduce this area by five-to-10 percentage points over about the next 20 years, which would see about 3,000 hectares of Auckland’s existing private green space gone.

"Twenty years from now a typical Auckland suburb will likely be between 0.5 and 1.0 °C warmer on average due to climate change alone."

Upton points to a recent global review of urban heat modelling that sets out to estimate the contributions of various factors, including green space.

"This meta-analysis estimated that a 10% increase in green space reduced neighbourhood average air temperatures by 0.3 °C. Hence, the magnitude of the temperature change due to green space gains or losses could be as much as half that predicted for Auckland by climate change over the next 20 years. This back-of-the-envelope calculation suggests that the expected loss of urban green space will be noticeable in terms of urban heat in Auckland in coming decades."

"Moreover, the impacts of trees are likely to be even larger when the localised cooling impacts of shading are considered," he adds.

"Sophisticated stormwater models are available and are used to design larger new developments. But even basic models – like Auckland’s online stormwater device sizing tool – can give some idea of what is to come as the city fills in and covers up. Using the tool, stormwater flows for an area roughly the size of a city block in Auckland that currently has 55% impervious area and 45% green space were compared with expected flows from the same area if the green space was reduced to 35%. For a rainfall event that delivers 24 millimetres of rain in 24 hours, this reduction in green space will mean that an extra 38 cubic metres of rainwater will need to be managed. This represents an 18% increase in volume that needs to go somewhere - from just one rainfall event."

"The future Auckland suburb will also likely produce much higher peak flows into its receiving environment because water will move faster over the increased proportion of impermeable surfaces. With fewer green spaces available to filter the water and air, more pollution can be expected to be deposited in these environments too," Upton says.

Hotter suburbs more prone to flooding

In summary, he says urban intensification and climate change mean a typical Auckland suburb will be hotter and more prone to flooding in future. But, he says, neither of those problems is unavoidable.

"They can be solved by existing engineering options: air conditioning is increasingly being used around the world to offer respite during hot periods, and the capacity of traditional stormwater infrastructure can be upgraded to mitigate flooding risk. These engineered solutions come with costs. But more importantly, they provide none of the biodiversity, recreational and cultural co-benefits that make green space such an important element of a healthy, liveable city," says Upton.

"Before building or sealing over more, it would be worth considering whether a future largely devoid of backyard nature is really one we want to live in. Or, if that is to be the outcome of urban planning, whether significant new areas of public green space need to be created. This, like engineered solutions, will be costly – and difficult to achieve in inner-city areas."

Environmental "services" green spaces provide, including temperature regulation, stormwater management, air filtration and habitat provision, don’t just benefit individuals, Upton says.

"They benefit everyone around them. They are a form of infrastructure every bit as important as pipes and roads."

“The ability of our trees and parks to filter stormwater flows and cool their immediate surroundings can mitigate some of the heat and excess water that impervious surfaces generate. These services will be in even higher demand as our cities become hotter and more subject to extreme rain events in a changing climate.”

Upton's recommendations

The report ends with a series of recommendations, detailed below.

Recommendation 1: Statutory planning documents adopted by regional councils and territorial authorities should include more explicit provisions on green spaces based on consultation with their communities.

These provisions should identify the key environmental, recreational and cultural services that green spaces provide, the extent to which these could be compromised by urban development, and the steps councils will take to avoid their loss taking into account the likely future effects of climate change.

Recommendation 2. Amend the Local Government Act 2002 and the National Policy Statement on Urban Development to ensure that urban green space is one of the mandatory things councils must plan and provide for.

Recommendation 3: The Ministry for the Environment – Manatū Mō Te Taiao should require councils to regularly monitor and measure urban green space using a standardised and consistent approach.

Recommendation 4: The Ministry for the Environment – Manatū Mō Te Taiao should provide guidance on how that monitoring should be carried so that a consistent and comparable approach is applied across councils.

Recommendation 5: The Ministry of Business, Innovation and Employment – Hīkina Whakatutuki and the Ministry for the Environment – Manatū Mō Te Taiao should ensure that publicly funded research extends to:

a) improving our understanding of the biophysical functions provided by urban green space; and

b) developing the tools needed to measure, monitor and manage urban green spaces.

Recommendation 6: Councils and relevant government agencies (e.g. Kāinga Ora – Homes and Communities, Waka Kotahi NZ Transport Agency, Ministry of Education – Te Tāhuhu o te Mātauranga) should implement policies to improve the quality and/or quantity of green space in suburbs where it is in decline or in otherwise short supply. At a minimum, policies should be evaluated that:

a) on publicly owned land, improve green space in parts of the road corridor, in existing parks and schools, and in other ‘forgotten’ or neglected corners of public land

b) on privately owned land, provide incentives for landowners and developers to retain and provide shrubs and trees (rather than just grass) in yards and to encourage more vertical development (provided green space is preserved or significant new green space is provided for).

Recommendation 7: Councils should identify, and consider purchasing, peri-urban land for large areas of public green space earlier in the planning process.

Recommendation 8: Central government could help to enable peri-urban public green space provision by: a) clarifying councils’ ability to acquire land for future public green space using the compulsory acquisition powers provided by the Public Works Act 1981

b) enabling councils to use value uplift taxes to help pay for bulk public infrastructure (including the land required for larger areas of public green space).