Systems Thinking is Needed to Achieve Sustainable Cities

Why a just transition to sustainable cities depends on quality, affordable housing

As city populations grow, a critical current and future challenge for urban researchers is to provide compelling evidence of the medium and long-term co-benefits of quality, low-carbon affordable housing and compact urban design. Philippa Howden-Chapman (University of Otago) and Ralph Chapman (Victoria University of Wellington) explain why systems-based, transition-oriented research on housing and associated systemic benefits is needed now more than ever.

The quality, ownership, affordability and security of housing all make critically important contributions to the health and wellbeing of individuals and communities. This is becoming increasingly important as we grapple with the climate and biodiversity crises. Yet, in many countries, affordable good-quality housing is underprovided, particularly in the private rental housing sector, where a focus on return on investment means more of these homes tend to be in poor condition.  Globally, more households cannot save enough to become owner-occupiers, or afford market rents, and public housing demand often outstrips supply. Increasing numbers of people are living in sub-standard houses, slums, or are homeless, which is additionally concerning as these communities are more vulnerable to epidemics like COVID-19 and the impacts of climate change (Howden-Chapman et al. 2023). Therefore challenging, critical pathways and system transitions in urban development need to be designed and followed, such as strategies for more compact development, to improve our chances of attaining higher quality housing and more sustainable communities (Chapman & Howden-Chapman 2021; Rydin et al. 2012).

Housing quality, wellbeing and sustainability

Far-sighted socially invested landlords, like governments, have clear incentives to develop on land that is not prone to flooding or landslips, and to provide necessary infrastructure for public and community housing. However, in the absence of interventions from government or others, slum dwellings are often built on vulnerable land, such as flood plains and steep valley slopes, which can lead to large death tolls during extreme climate events, e.g. heavy rainfalls and floods. This is deeply concerning as these, and other events including fire, are burgeoning threats as climate change accelerates. Poor quality housing and people on lower incomes are also more vulnerable to damage from natural hazards, e.g. earthquakes, which is especially concerning for ‘Pacific Ring of Fire’ countries like Aotearoa New Zealand (AoNZ) (Howden-Chapman et al. 2014). Housing quality and location are therefore intrinsically linked to the exposure of occupants to risks that affect their health and wellbeing.

In the next 5 years, countries and cities will have to make major, tangible progress in mitigating and responding to the climate crisis. The United Nations Environment Programme states that countries need to cut GHG emissions by 42% by 2030 to keep warming within 1.5^oC (UNEP 2023a). Globally, buildings generate between 21% (IPCC 2022) and 37% (UNEP 2023b) of energy-related carbon emissions. This figure is estimated to be around 20% in AoNZ when the embodied carbon building products is included (Grant et al. 2021). A major societal risk comes from new construction of homes due to large amounts of embodied carbon in construction materials which is released into the atmosphere during the manufacturing process (Ürge-Vorsatz 2021). Thus, approaches to minimising embodied emissions, such as accelerating the use of bio-based materials like cross-laminated timber (which lock in carbon) to replace concrete and steel are needed.

Public housing, compact design and sustainable communities

Public housing encompasses state, social, and community housing (Howden-Chapman 2004; Mansour et al. 2022). Providing adequate quality public housing reduces societal vulnerability and promotes the sustainability of the homes and communities and the wellbeing of occupants. When broader societal considerations are incorporated into urban planning, value is placed on upgrading existing homes, ensuring occupant welfare, and importantly, ensuring homes are closer to amenities, such as parks, schools, places of work and public transport. In 2019, global transport was estimated to generate about 23% of energy-related carbon emissions (IPCC 2022); in AoNZ the estimate is about 40% of carbon emissions. Thus, sustainable communities also involve ensuring cities are compact and better served by public and active transport like cycling and walking is a critical part of functional urban systems.

When capital is provided by the state, the houses are public assets, which, in turn, can be leveraged to increase capital to improve the stock of affordable housing. Other potential sources of funding for social and community housing may be from trusts, charities and non-governmental organisations, (although tenants can receive government subsidies). However, where funding social housing comes from private sector borrowing, the debt may be converted to equity, leading to the gradual privatisation of community housing which may be less likely to consider citing of developments within easy access to essential public amenities and jobs.

AoNZ’s Public Housing and Urban Regeneration Programme

Governments must carefully assess counterfactual and competing investments in the housing and urban development domain in order to understand wider impacts for wellbeing and sustainability. The systems approach recognises that the important elements of what people strive for are integrally linked. Urban wellbeing and sustainability are clearly connected outcomes, each of which depends on the quality of housing, a community’s access to low-carbon energy and transport provision, and other infrastructure investment.

The Public Housing and Urban Regeneration Programme (PHUR) in AoNZ exemplifies urban systems thinking focused on the goals of wellbeing and environmental sustainability (https://www.sustainablecities.org.nz/our-research). It is providing an exemplar of the UN Sustainable Development Goals framework to highlight the co-benefits of public housing and urban regeneration for health and wellbeing and sustainability (Howden-Chapman et al. 2017; Nilsson et al. 2018). The multi-disciplinary researcher team of social scientists, epidemiologists, Māori and Pacific researchers, economists and engineers collaborate to provide robust and timely advice for policy makers on the importance of public housing and urban regeneration.  Both qualitative and quantitative data are used in the modelling to identify and distil the key causal relationships and system effects, such as the links between housing location and design, wellbeing and carbon emissions.

The PHUR programme assesses housing policies in terms of advancing widely supported wellbeing goals, using whole-of-society costs and benefits. The aim is to encompass a wide range of factors that enable people to live fulfilling lives. To assess public housing in terms of sustainability, we are measuring the most critical environmental variables: CO₂ emissions embodied in housing construction; and operational CO₂ emissions associated with housing energy use and tenants’ travel patterns.

To assess public housing in terms of broad wellbeing goals, our methods, apart from interviews and surveys, include analysing tenants’ social and economic outcomes before and after they become tenants. We use the (deidentified) unique Stats NZ integrated data infrastructure (IDI), which collects details of all contacts the NZ population has with government services, e.g. social services, hospitals, education, police, etc.  

There is little research that analyses the systemic benefits of public housing investment compared to investment in social and community housing. In PHUR, we explore the relative strengths and weaknesses of different models of housing provision and examine the implications for the wellbeing and health of occupants, using indicators such as the desirability of neighbourhoods (indicated by tenants’ sense of place), and the environmental sustainability of the models (informed by GIS data to determine distances from housing to local amenities). Allied research can also help identify how urban green space contributes to addressing the biodiversity crisis, through strategies for design, maintenance and expansion of urban green space (Blaschke et al. 2024).

Conclusion

The major challenge facing cities in the near term is how to plan and accelerate a just transition to a more sustainable way of life. Critical and often lagging sectors in this transition are housing and transport, which of course depend on infrastructure such as pipe and power networks, and underlying systems of sound and stable governance. Governments need to consider interactions among sectors (such as land development driving transport emissions) and spillover costs or co-benefits for wellbeing, health and environmental sustainability. Systems-based, transition-oriented research in this area is critical if governments are to make well-informed decisions regarding the future of their cities.

References

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Rydin, Y., Bleahu, A., Davies, M., Dávila, J.D., Friel, S., Grandis, G.D., Groce, N., Hallal, P. C., Hamilton, I., Howden-Chapman, P., Lai, K.M., Lim, C., Martins, J., Osrin, D., Ridley, I., Scott, I., Taylor, M., Wilkinson, P. & Wilson, J. (2012). UCL-Lancet Commission: Shaping cities for health: the complexity of planning urban environments in the 21st century. The Lancet, 379(9831), 2079-2108.

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Ürge-Vorsatz, D. (2021). 1.5⁰C of global warming: can we still get there?  Insights from the urban development sector. In L. Grant, H. Viggers & Howden-Chapman P (Eds.), Improving Buildings, Cutting Carbon. Steele Roberts, Aotearoa.

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