Arbres urbains ou toitures réfléchissantes : quelle est la meilleure solution pour les villes afin de lutter contre la chaleur ?

Les arbres comme ceux-ci à Boston peuvent aider à rafraîchir les quartiers pendant les journées chaudes. Yassine Khalfalli/Unsplash, CC BY

Ian Smith, Boston University and Lucy Hutyra, Boston University

Lorsque la chaleur estivale s'installe, les villes peuvent commencer à ressembler à des fours, car les bâtiments et les chaussées emprisonnent la chaleur du soleil, tandis que les véhicules et les climatiseurs rejettent davantage de chaleur dans l'air.

La température dans un quartier urbain dans lequel il y a peu d'arbres peut être supérieure de 5,5 degrés Celsius à celle des quartiers voisins. Cela signifie que la climatisation fonctionne davantage, mettant le réseau électrique à rude épreuve et exposant les habitants aux pannes de courant.

Il existe des mesures éprouvées que les villes peuvent prendre pour rafraîchir l'air, par exemple planter des arbres qui fournissent de l'ombre et de l'humidité, ou créer des toitures réfléchissantes qui réfléchissent le rayonnement solaire vers l'atmosphère au lieu de l'absorber.

Mais ces mesures sont-elles efficaces partout ?

Nous étudions les risques liés à la chaleur dans les villes en tant qu'écologistes urbains, et analysons l'impact de la plantation d'arbres et des toitures réfléchissantes dans différentes villes et différents quartiers. Nos conclusions peuvent aider les villes et les propriétaires à mieux cibler leurs efforts pour lutter contre la chaleur.

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Cet article fait partie de notre série Nos villes d’hier à demain. Le tissu urbain connait de multiples mutations, avec chacune ses implications culturelles, économiques, sociales et – tout particulièrement en cette année électorale – politiques. Pour éclairer ces divers enjeux, La Conversation invite les chercheuses et chercheurs à aborder l’actualité de nos villes.

La magie des arbres

Les arbres urbains offrent une protection naturelle contre la hausse des températures. Ils apportent de l'ombre et libèrent de la vapeur d'eau par leurs feuilles, un processus similaire à la transpiration humaine. Cela refroidit l'air ambiant et atténue la chaleur de l'après-midi.

L'ajout d'arbres dans les rues, les parcs et les jardins résidentiels peut changer sensiblement la température ressentie dans un quartier, les quartiers arborés étant près d'1,7 °C plus frais que ceux qui le sont moins.

La comparaison des cartes de la végétation et de la température de New York montre l'effet rafraîchissant des parcs et des quartiers plus boisés. Sur la carte de gauche, les couleurs plus claires correspondent aux zones moins boisées. Les zones claires de la carte de droite sont plus chaudes. NASA/USGS Landsat

Mais planter des arbres n'est pas toujours simple.

Dans les villes chaudes et sèches, les arbres ont souvent besoin d'être irrigués pour survivre, ce qui peut mettre à l'épreuve des ressources en eau déjà limitées. Les arbres doivent survivre pendant des décennies pour atteindre une taille suffisante afin de fournir de l'ombre et libérer assez de vapeur d'eau pour réduire la température de l'air.

Les coûts d'entretien annuels, estimés à environ 900 dollars américains annuels par arbre à Boston, peuvent dépasser l'investissement initial de plantation.

La difficulté, c'est que les quartiers urbains denses, où la chaleur est la plus intense, sont souvent trop encombrés de bâtiments et de routes pour permettre la plantation d'arbres supplémentaires.

Comment les toitures réfléchissantes peuvent aider pendant les journées chaudes

Une autre option consiste à recourir aux toitures réfléchissantes. Recouvrir les toitures d'une peinture réfléchissante ou utiliser des matériaux de couleur claire permet aux bâtiments de réfléchir davantage la lumière du soleil vers l'atmosphère au lieu de l'absorber sous forme de chaleur.

Ces toitures peuvent réduire la température à l'intérieur d'un immeuble sans climatisation d'environ 1 à 3,3 °C et peuvent réduire la demande maximale de climatisation jusqu'à 27 % dans les bâtiments climatisés, selon une étude. Elles peuvent également procurer un rafraîchissement immédiat en réduisant les températures extérieures dans les zones densément peuplées. Les coûts d'entretien sont aussi plus faibles que ceux liés à l'expansion des forêts urbaines.

Deux ouvriers appliquent un revêtement blanc sur le toit d'une maison mitoyenne à Philadelphie. AP Photo/Matt Rourke

Cependant, tout comme les arbres, les toitures réfléchissantes ont leurs limites. Elles sont plus efficaces sur les toits plats que sur les toits en pente recouverts de bardeaux, car les toits plats sont souvent recouverts de caoutchouc qui emprisonne la chaleur et sont exposés à un ensoleillement plus direct l'après-midi.

Les villes disposent également d'un nombre limité de toits susceptibles d'être convertis. Et dans les villes qui comptent déjà de nombreux toits de couleur claire, quelques toitures supplémentaires pourraient contribuer à réduire les coûts de climatisation dans ces bâtiments, mais elles n'auraient pas beaucoup d'effet à l'échelle du quartier.

En évaluant les avantages et les inconvénients des deux stratégies, les villes peuvent concevoir des plans adaptés à leur situation pour lutter contre la chaleur.

Choisir la bonne combinaison de solutions de refroidissement

De nombreuses villes à travers le monde ont pris des mesures pour s'adapter à la chaleur extrême, avec des programmes de plantation d'arbres et de toitures réfléchissantes qui imposent des exigences en matière de réflectivité ou en encouragent l'adoption.

À Detroit, des organisations à but non lucratif ont planté plus de 166 000 arbres depuis 1989. À Los Angeles, les codes du bâtiment exigent désormais que les toits des nouvelles constructions résidentielles respectent des normes de réflectivité spécifiques.

Dans une étude récente, nous avons analysé le potentiel de Boston pour réduire la chaleur dans les quartiers vulnérables de la ville. Les résultats montrent comment une stratégie à coût maîtrisé pourrait apporter des bénéfices significatifs en matière de refroidissement.

Par exemple, nous avons constaté que la plantation d'arbres peut refroidir l'air de 35 % de plus que l'installation de toitures réfléchissantes dans les endroits où il est possible de planter des arbres.

Cependant, la plupart des meilleurs emplacements pour planter de nouveaux arbres à Boston ne se trouvent pas dans les quartiers qui en ont le plus besoin. Dans ces quartiers, nous avons constaté que les toitures réfléchissantes constituaient un meilleur choix.

En investissant moins de 1 % du budget annuel de fonctionnement de la ville, soit environ 34 millions de dollars, dans 2 500 nouveaux arbres et 3 000 toitures réfléchissantes ciblant les zones les plus à risque, nous avons constaté que Boston pourrait réduire l'exposition à la chaleur pour près de 80 000 habitants. Cela permettrait de réduire la température de l'air l'après-midi en été de plus de 0,6 °C dans ces quartiers.

Bien que cette baisse puisse sembler modeste, il a été démontré que des réductions de cette ampleur diminuent sensiblement les maladies et les décès liés à la chaleur, augmentent la productivité et réduisent les coûts énergétiques liés à la climatisation des bâtiments.

Toutes les villes ne bénéficieront pas de la même combinaison. Le paysage urbain de Boston comprend de nombreux toits plats et noirs qui ne réfléchissent qu'environ 12 % de la lumière solaire, ce qui rend les toitures réfléchissantes qui réfléchissent plus de 65 % de la lumière solaire particulièrement efficaces. Boston bénéficie également d'une saison de végétation relativement humide qui favorise le développement d'un couvert forestier urbain luxuriant, rendant ces deux solutions viables.

Phoenix, à gauche, compte déjà de nombreux toits de couleur claire, contrairement à Boston, à droite, où les toits sont principalement sombres. Imagerie Google 2025

Dans les endroits où il y a moins de toits plats et sombres pouvant être convertis en toitures réfléchissantes, la plantation d'arbres peut apporter davantage de bénéfices. À l'inverse, dans les villes où il reste peu d'espace pour planter de nouveaux arbres ou où la chaleur extrême et la sécheresse limitent la survie des arbres, les toitures réfléchissantes peuvent être une meilleure solution.

Phoenix, par exemple, compte déjà de nombreux toits de couleur claire. Les arbres pourraient être une option, mais ils nécessiteraient un système d'irrigation.

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Apporter les solutions là où les gens en ont besoin

La création de zones ombragées le long des trottoirs peut avoir un double effet en offrant aux piétons un endroit pour s'abriter du soleil et en rafraîchissant les bâtiments. À New York, par exemple, les arbres de rue représentent environ 25 % de la forêt urbaine totale.

Les toitures réfléchissantes peuvent être plus difficiles à déployer pour les autorités publiques, car elles nécessitent la collaboration des propriétaires. Cela signifie souvent que les villes doivent proposer des mesures incitatives. Louisville, dans le Kentucky, par exemple, accorde des rabais pouvant aller jusqu'à 2 000 dollars aux propriétaires qui installent des matériaux de toiture réfléchissants, et jusqu'à 5 000 dollars aux entreprises commerciales dotées de toits plats qui utilisent des revêtements réfléchissants.

À Boston, la plantation d'arbres (à gauche) et l'augmentation de la réflectivité des toitures (à droite) se sont avérées des moyens efficaces pour refroidir les zones urbaines. Ian Smith et al. 2025

De telles initiatives peuvent contribuer à étendre les bénéfices des toitures réfléchissantes dans les quartiers densément peuplés qui ont le plus besoin d'être rafraîchis.

Alors que les changements climatiques entraînent une augmentation de la fréquence et de l'intensité des vagues de chaleur urbaine, les villes disposent d'outils puissants pour faire baisser la température. En prêtant attention à ce qui existe déjà et à ce qui est faisable, elles peuvent trouver la meilleure stratégie en fonction de leurs besoins et de leurs réalités.

Ian Smith, Research Scientist in Earth & Environment, Boston University and Lucy Hutyra, Distinguished Professor & Chair of Earth and Environment, Boston University, Boston University

Cet article est republié à partir de The Conversation sous licence Creative Commons. Lire l’article original.

Canada could use thermal infrastructure to turn wasted heat emissions into energy

James (Jim) S. Cotton, McMaster University and Caleb Duffield, McMaster University

Buildings are the third-largest source of greenhouse gas emissions in Canada. In many cities, including Vancouver, Toronto and Calgary, buildings are the single highest source of emissions.

The recently launched Infrastructure for Good barometer, released by consulting firm Deloitte, suggests that Canada’s infrastructure investments already top the global list in terms of positive societal, economic and environmental benefits.

In fact, over the past 150 years, Canada has built railways, roads, clean water systems, electrical grids, pipelines and communication networks to connect and serve people across the country.

Now, there’s an opportunity to build on Canada’s impressive tradition by creating a new form of infrastructure: capturing, storing and sharing the massive amounts of heat lost from industry, electricity generation and communities, even in summer.

Natural gas precedent

Indoor heating often comes from burning fossil fuels — three-quarters of Ontario homes, for example, are heated by natural gas. Until about 1966, homes across Canada were primarily heated by wood stoves, coal boilers, oil furnaces or heaters using electricity from coal-fired power plants.

After the oil crisis of the 1970s, many of those fuels were replaced by natural gas, delivered directly to individual homes. The cost of the natural gas infrastructure, including a national network of pipelines, was amortized over more than 50 years to make the cost more practical.

Sources of greenhouse gas emissions in Ontario. (J. Cotton), CC BY

This reliable, low-cost energy source quickly proved to be popular. The change cut heating emissions across Ontario by roughly half throughout the 1970s and 1980s, long before climate change was the concern it is today.

Now, as the need to decarbonize becomes more pressing, recent studies not only emphasize the often-overstated emissions reductions benefits from using natural gas; they also indicate that burning this fuel source is still far from net-zero.

However, there’s no reason why Canadian governments can’t invest in new infrastructure-based alternative heating solutions. This time, they could replace natural gas with an alternative, net-zero source: the wasted heat already emitted by other energy uses.

Heat capture and storage

Depending on the source temperature, technology used and system design, heat can be captured throughout the year, stored and distributed as needed. A type of infrastructure called thermal networks could capture leftover heat from factories and nuclear and gas-fired power plants.

In essence, thermal networks take excess thermal energy from industrial processes (though thermal energy can theoretically be captured from a variety of different sources), and use it as a centralized heating source for a series of insulated underground pipelines connected to multiple other buildings. These pipelines, in turn, are used to heat or cool these connected buildings.

A substantial potential to capture heat similarly exists in every neighbourhood. Heat is produced by data centres, grocery stores, laundromats, restaurants, sewage systems and even hockey arenas.

In Ontario, the amount of energy we dump in the form of heat is greater than all the natural gas we use to heat our homes.

A restaurant, for example, can produce enough heat for seven family homes. To take advantage of the wasted heat, Canada needs to build thermal networks, corridors and storage to capture and distribute heat directly to consumers.

The effort demands substantial leadership from all levels of government. Creating these systems would be expensive, but the technology does exist, and the one-time cost would pay for itself many times over.

Such systems are already working in other cold countries. Thermal networks heat half the homes in Sweden and two-thirds of homes in Denmark.

District heating pipes being laid at Gullbergs Strandgata in Gothenburg, Sweden in May 2021. (Shutterstock)

The oil crisis of the 1970s motivated both countries to find new domestic heating sources. They financed their new infrastructure over 50 years and reduced their investment risks through low-interest bonds (loaned by public banks) and generous subsidies.

These were offered to utility companies looking to expand district energy operations, and to consumers by incentivizing connections to such systems. Additionally, in Denmark, controlled consumer prices served a similar function.

At least seven American states have established thermal energy networks, with New York being the first. The state’s Utility Thermal Energy Network and Jobs Act allows public utilities to own, operate and manage thermal networks.

They can supply thermal energy, but so can private producers such as data centres, all with public oversight. Such a strategy avoids monopolies and allows gas and electric utilities to deliver services through central networks.

An opportunity for Canada

Canada has a real opportunity to learn from the experiences of Sweden, Denmark and New York. In doing so, Canada can create a beneficial and truly national heating system in the process. Beginning with federal government leadership, thermal networks could be built across Canada, tailored to the unique and individual needs, strengths and opportunities of municipalities and provinces.

Such a shift would reduce emissions and generate greater energy sovereignty for Canada. It could drive a just energy strategy that could provide employment opportunities for those displaced by the transition away from fossil fuels, while simultaneously increasing Canada’s economic independence in the process.

Thermal networks could be built using pipelines made from Canadian steel. Oil-well drillers from Alberta could dig borehole heat-storage systems. A new market for heat-recovery pumps would create good advanced-manufacturing jobs in Canada.

Funding for the infrastructure could come through public-private partnerships, with major investments from public banks and pension funds, earning a solid and secure rate of return. A regulated approach and process could permit this infrastructure cost to be amortized over decades, similar to the way past governments have financed gas, electrical and water networks.

As researchers studying the engineering and policy potential of such an opportunity, we view such actions as essential if net-zero is to be achieved in the Canadian building sector. They are also a win-win solution for incumbent industry, various levels of government and citizens across Canada alike.

Yet efforts to install robust thermal networks remain stalled by institutional inertia, the strong influence of the oil industry, limited citizen awareness of the technology’s potential and a tendency for government to view the electrification of heating as the primary solution to building decarbonization.

In this time of environmental crisis and international uncertainty, pushing past these barriers, drawing on Canada’s lengthy history of constructing infrastructure and creating this new form thermal energy infrastructure would be a safe, beneficial and conscientious way to move Canada into a more climate-friendly future.

James (Jim) S. Cotton, Professor, Department of Mechanical Engineering, McMaster University and Caleb Duffield, PhD Candidate in Political Science, McMaster University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

How women are trapped in years of homelessness that often begin in their teens

Mary Vaccaro, McMaster University

Many women without children in their care who become homeless in Canada remain homeless for many years. Yet their experiences remain misunderstood and largely ignored because of the ways we define and measure homelessness in Canada.

I have worked in the women’s emergency shelter system in Hamilton, Ont., since 2012. I have met many women who have been navigating homelessness for years — with no permanent solution to their housing crisis. For my PhD in social work, I interviewed 21 women who had experienced homelessness for a year or longer in Hamilton. I asked them about their experiences, and through art-based activities, about their ideas for housing and support.

What I learned in the interviews, combined with existing research, highlights a hidden crisis. Within our current system resides a profound human cost that manages, instead of resolves, homelessness.

Many women who experience homelessness do so for far longer than the federal government’s definition of chronic homelessness, which is six consecutive months or 18 months over three years. Research from the United Kingdom that focuses on long-term and unresolved homelessness for women found that the ways women experience homelessness is to “go around in circles” without having their housing or support needs met.

Among the women I spoke with, more than half had been experiencing homelessness for 10 years or longer. Six of the the women said they have never had a safe place of their own to live for the entirety of their adult lives.

All of the women who participated in this project accessed the services offered by the homeless serving sector, including shelters and outreach workers, designed to resolve their homelessness. Yet none of these women were able to have their housing and support needs met.

This means their experience of homelessness has persisted for years, and even decades.

Homelessness often starts in their teens

More than half of the participants I spoke with first experienced homelessness before they turned 18. Their primary route into youth homelessness was gender-based violence. They ran away from home when they were teenaged girls to escape violence and became caught in a cycle of events that include: hospitalization, incarceration, staying in youth shelters, living in group homes and unsafe places.

The Pan-Canadian Women’s Housing and Homelessness Survey, as well as a study on Toronto youth, echo what the women I spoke with told me. Studies from the United States also confirm similar patterns — homelessness begins early in life for a majority of women, and is often followed by a chronic, chaotic churn of precarious housing and homelessness situations.

The women in my study described a frustrating and exhausting cycle of going among institutions such as hospitals, jails, emergency shelters, drop-in programs and transitional housing programs. They had all spent periods of time living outdoors, in encampments, in motels, with unsafe people and in other precarious and temporary housing arrangements. This phenomena is well-documented in existing Canadian research.

Better definitions, better data

The Canadian government defines those who have been homeless and using shelters for more than 180 days a year as experiencing “acute chronicity.”

Another term used by the federal government for individuals who have accessed shelters at least once in each of the last three years is “prolonged instability.”

People who meet one or both of these criteria are considered to have the highest housing needs in the country.

According to recent federal data, women and gender-diverse people across Canada experience slightly higher rates of acute chronicity than men (13.4 per cent for men, 15.4 per cent for women, and 13.9 per cent for gender-diverse people). But the real numbers for women are likely much higher due to under-reporting.

Research shows women remain invisible to official systems during periods of homelessness. For example, the available data relies solely on information about emergency shelter usage. It does not capture experiences of homelessness that occur outside of the shelter system.

Women are less likely than their male counterparts to access shelters and other formal supports. Instead, they rely on precarious, unsafe and temporary housing arrangements to navigate homelessness.

In Canada, there are also fewer emergency women-specific shelter beds than for men

Rethinking responses to long-term homelessness

For the women I spoke with, the official 180 days or three years that makes someone officially chronically homeless in Canada does not even begin to describe the length and complexity of their experiences of homelessness.

They described wanting to live in supportive, gender-specific housing programs that foster community and care. Highly supportive housing typically integrates health and social services and a range of other support services. This type of integrated housing does exist across Canada — examples are the Block Line Supportive Housing Program operated by YWCA Kitchener-Waterloo and the Women’s Building (Alpha House) in Calgary — but there is not enough of it.

The current measurements from the government of Canada fall short of capturing the complexity of the homeless experience for many Canadian women.

Government officials must therefore not only rethink their definitions of those in the most housing need, they must develop responsive housing solutions to meet the needs of women who have been homeless for many years.

Mary Vaccaro, Lecturer in Social Work, McMaster University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Five ways to make cities more resilient to climate change

John_T/Shutterstock

Paul O'Hare, Manchester Metropolitan University

Climate breakdown poses immense threats to global economies, societies and ecosystems. Adapting to these impacts is urgent. But many cities and countries remain chronically unprepared in what the UN calls an “adaptation gap”.

Building climate resilience is notoriously difficult. Economic barriers limit investment in infrastructure and technology. Social inequities undermine the capacity of vulnerable populations to adapt. And inconsistent policies impede coordinated efforts across sectors and at scale.

My research looks at how cities can better cope with climate change. I have identified five ways to catalyse more effective – and ultimately more progressive – climate adaptation and resilience.

1. Don’t just ‘bounce back’ after a crisis

When wildfires, storms or floods hit, all too often governments prioritise rebuilding as rapidly as possible.

Though understandable, resilience doesn’t just entail coping with the effects of climate change. Instead of “bouncing back” to a pre-shock status, those in charge of responding need to encourage “bouncing forward”, creating places that are at less risk in the first place.

After the Christchurch earthquake in February 2011, the New Zealand authorities “built back better”, improving building codes and regulations and relocating vulnerable communities. Critics suggested reconstruction provided too much uncertainty and failed to acknowledge private property rights. But the rebuild did encourage better integration of planning policies and land use practices.

Swales and sustainable urban drainage in Gorton climate resilient park, Manchester, UK. Paul O'Hare, CC BY-NC-ND

2. Informed by risk

It can be difficult to predict what the consequences of a crisis might be. Cities are complex, interconnected places. Transboundary risks – the consequences that ripple across a place – must be taken into account.

The best climate adaptation plans recognise that vulnerability varies across places, contexts and over time. The most effective are holistic: tailored to specific locations and every aspect of society.

Assessments must also consider both climatic and non-climatic features of risk. In 2015, in the UK, a flood affected one of Lancaster’s electrical substations, causing a city-wide power failure that took several days to rectify. In this instance, as with so many others, people had to deal not just with the direct impacts of flooding, but the ‘cascading’ or knock-on impacts of infrastructure damage.

Many existing assessments have limited scope. But others do acknowledge how ageing infrastructures and pressures to develop land to accommodate ever intensifying urban populations exacerbate urban flood risk. Others too, such as the recently published Cambridge climate risk plan, detail how climate risk intersects with the range of services provided by local government.

Systems thinking – an approach to problem-solving that views problems as part of wider, interconnected systems – can be applied to identify interdependencies with other drivers of change.

Good risk assessments will, for example, take note of demographics, age profiles and the socio-economic circumstances of neighbourhoods, enabling targeted support for particularly vulnerable communities. This can help ensure communities and systems adapt to evolving challenges as climate change intensifies, and as society evolves over time.

Complex though this might be, city leaders can access advice about improving risk assessments, including from the C40 network, a global coalition of 100 mayors committed to addressing climate change.

3. Transformative action

There is no such thing as a natural disaster. The effects of disasters including floods and earthquakes are influenced by pre-existing, often chronic, social and economic conditions such as poverty or poor housing.

Progressive climate resilience looks beyond the immediacy of shocks, attending to the underlying root causes of vulnerability and inequality. This ensures that society is not only better prepared to withstand adverse events in the future, but thrives in the face of uncertainty.

Progressive climate resilience therefore demands tailored responses depending on the population and place. In Bangladesh, for instance, communities are building floating gardens to grow crops during floods. These enhance food security and provide a sustainable livelihood option in flood-prone areas.

Floating vegetable gardens in Bangladesh. Mostafijur Rahman Nasim/Shutterstock

4. Collective approaches

Effective climate resilience demands collective action. Sometimes referred to as a “whole of society” response, this entails collaboration and shared responsibility to address the multifaceted challenges posed by a changing climate.

The most effective initiatives avoid self-protection, of people, buildings and cities alike, and consider both broader and longer-term risks. For instance, developments not at significant risk should still incorporate adaptation measures including rainwater harvesting or enhanced greening to lower a city’s climate risk profile and benefit local communities, neighbouring authorities and surrounding regions.

So, progressive resilience is connected, comprehensive and inclusive. Solidarity is key, leveraging resources to address common challenges and fostering a sense of shared purpose and mutual support.

Solar panels on the surface of a reservoir not only provide a source of renewable energy but also provide shade and therefore help conserve water. Tom Wang/Shutterstock

5. Exploiting co-benefits

The most effective resilience projects exploit co-benefits – what the UN calls “multiple resilience dividends” – to leverage additional benefits across sectors and policies, reducing vulnerability to shocks while addressing other social and environmental challenges.

In northern Europe, for example, moorlands can be restored to retain water helping alleviate downstream flooding, but also to capture carbon and provide vital habitats for biodiversity.

In south-East Asia solar panels installed on reservoirs generate renewable energy to reduce greenhouse gas emissions, while providing shade to reduce evaporation and conserve water resources during droughts.

In short, adaptation is obviously crucial for tackling climate change across the globe. But the real challenge is to deal with the impacts of climate change while simultaneously creating communities that are fairer, healthier, and better equipped to face any manner of future risks.

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Get a weekly roundup in your inbox instead. Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. Join the 40,000+ readers who’ve subscribed so far.

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Paul O'Hare, Lecturer in Human Geography and Urban Development, Manchester Metropolitan University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Ontario Professional Planners Climate Action Guide

The Ontario Professional Planners Institute (OPPI) in partnership with the Climate Risk Institute (CRI) and the Ontario Resource Centre for Climate Adaptation (ORCCA) have announced the publication of a Climate Change Adaptation Practice Guide.

The guide aims to recognize the important role Registered Professional Planners (RPPs) play in helping Ontario adapt to climate change as well as support individual communities in building resilience against the climate threats they may face. To read the guide (68 pages) click here

Large cities such at the Waterloo region have instituted a programme of High Performance Standards that are aimed at reducing greenhouse gas emissions. The plan is to engage with industry and the community to ensure a consistent set of standards that address climiate change. To read more, click here.

Net-zero homes are touted as a solution for climate change, but they remain out of reach for most

Net-zero homes play an important role in combating climate change. (Shutterstock)

Ehsan Noroozinejad Farsangi, University of British Columbia and T.Y. Yang, University of British Columbia

Net-zero homes use natural energy sources and are designed to use less energy and, as such, are considered important in the fight against climate change. But for the average Canadian, they’re still out of reach.

Net-zero homes are important for tackling climate change. This includes both net-zero energy (NZE) homes, which produce as much energy as they use each year, and net-zero carbon (NZC) homes, which don’t release any carbon dioxide.

Released in the summer of 2024, the Canada Green Buildings Strategy outlines a bold vision to transform the country’s building sector, aiming for net-zero emissions and enhanced resilience by 2050. This is a bold step forward, but transforming the sector will require sustained collaboration across all levels of government, industry and communities.

CTV News covers the federal government’s Green Buildings Strategy.

Net-zero homes use green energy sources and efficient designs to match the amount of energy they produce with the amount they use. They use strategies like thermal shells that use less energy, high-performance components and the addition of green energy systems.

Net-zero homes also help Canada reach larger climate goals by reducing the amount of carbon dioxide it releases into the air.

Purchasing and installing these technologies can be cost-prohibitive, but in the long run, homeowners both save money on power bills and reduce their greenhouse gas emissions.

Those who are unable to make changes to their homes can still live in a net-zero way by buying green power or carbon offsets.

The sustainable housing market

Net-zero homes are becoming more popular in Canada. To speed up building processes and reduce costs, builders are trying out pre-fabricated and modular building techniques.

In 2024, the Canadian federal government announced a $600 million package of loans and funding to help make it easier and cheaper to build homes. This funding will support innovative technologies like pre-fabricated and modular construction, robotics, 3D-printing and mass timber to build homes faster and cheaper.

The Net Zero Council of the Canadian Home Builders’ Association has also been important in enhancing standards and practices and promoting novel approaches that cut costs while still being environmentally friendly. In doing so, CHBA drives the adoption of cheaper, environmentally friendly technologies and processes, enhancing industry standards and practices across Canada.

While CHBA collaborates with government agencies, such as Natural Resources Canada to promote innovation and elevate industry standards. Government programs typically provide funding, technical support and policy guidance, whereas CHBA focuses on training, best practices and market development for its members.

Government research programs through CanmetENERGY also work to improve technologies and give builders and planners the tools they need.

There are several reasons that owning a net-zero home has not yet become widespread. These include: high initial costs, limited awareness and education, gaps in policy and regulation and market challenges including difficulties in scaling up and integrating net-zero technologies.

Future directions

To make net-zero homes accessible to all Canadians, a multi-faceted approach is required.

Increased subsidies and incentives and expanding financial support for both builders and buyers can lower barriers to entry. The government of Canada’s 2030 Emission Reduction Plan includes $9.1 billion in new investments over the next eight years — adding to the $17 billion announced in 2021 — to support decarbonization efforts.

Enhancing public awareness and developing educational campaigns highlighting the cost savings and environmental benefits of net-zero homes are both essential approaches to raising awareness and support.

Policy reform can accelerate adoption of net-zero homes. Examples include harmonizing building codes and introducing mandatory energy efficiency standards to accelerate adoption.

Supporting continued research into technical innovation and developing cost-effective materials and renewable energy systems will drive down costs. Investment in modern methods of construction should be prioritized to accelerate the transition toward sustainable and energy-efficient building practices.

Partnerships between governments, private developers and non-profits can bring together resources and expertise to scale net-zero housing initiatives.

The Sustainable Finance Action Council recommends steps to mobilize private capital to support decarbonization and climate resilience in the Canadian economy, including in the housing sector.

Solar panels the roofs of apartment buildings in Munich, Germany. (Shutterstock)

Successful international models

Several countries have demonstrated how net-zero homes can become a reality through innovative policies, community-driven approaches and public-private partnerships:

BedZED in the United Kingdom is the country’s first eco-village project. It uses community-focused design and renewables to significantly cut carbon footprints.

The Passive House standard is a German housing policy that sets a global benchmark for ultra-low energy consumption, emphasizing airtight construction and heat recovery.

California’s ambitious Zero Net Energy policies help reduce overall carbon footprints by driving cutting-edge home construction practices.

The Net Zero Energy House (ZEH) Program in Japan encourages advanced insulation, efficient appliances and rooftop solar.

The Netherlands is a leader in innovative, large-scale retrofitting for net-zero housing, most notably through the Energiesprong program.

These international models highlight that success lies in integrating strong policy frameworks, advanced technology and collaborative practices. They demonstrate that with the right mix of government support, industry innovation and residents embracing green choices, net-zero living can become more widespread.

Housing is an important part of how to address climate change. As Canada pushes to make net-zero homes more affordable, each step forward strengthens communities, reduces greenhouse gas emissions and helps homeowners save money.

Ehsan Noroozinejad Farsangi, Visiting Senior Researcher, Smart Structures Research Group, University of British Columbia and T.Y. Yang, Professor, Structural & Earthquake Engineering, University of British Columbia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

City of Mississauga Housing Task Force Report

The City of Missisauga has a four-year action plan to get more housing built and make it more affordable. Read the comprehensive report that will guide Mississauga’s housing efforts going forward here. 

Reform development charges, taxes and fees to help lower housing costs

In Canada, 95% of new homes are built by the private sector. The task force recommends 14 actions to help balance demand and incentivize more affordable housing development.

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Update building and design standards to boost supply and make building more affordable

Guidelines and standards should help good city-building, not hinder it. The task force recommends 7 actions that will help create efficiencies across the industry to increase supply.

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Transform zoning to unlock more housing

Zoning reform provides certainty for developers and can help streamline the development application process. The task force recommends 5 actions that help transform Mississauga into a dynamic urban city.

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Create sustainable program and funding for affordable housing to mobilize industry

Mobilizing the private sector can help meet the demand for affordable housing. The task force recommends 4 actions to help develop a sustainable, long-term funding program for affordable housing.

Why improving social housing could be remarkably simple (and affordable)

Nicky Shaw, University of Leeds and Simon Williams, University of Leeds

Tragedies in social housing, such as the Grenfell Tower fire in 2017 and the death of toddler Awaab Ishak due to damp living conditions in 2020, remain shocking. As a coroner commented at the time, “How in the UK in 2020 does a two-year-old child die as a result of exposure to mould?”

Since then developments like Awaab’s Law have increased landlords’ accountability for delivering decent homes. However, improvements to housing stock may appear to be happening at a snail’s pace, as shown by the tower block fire in Dagenham, east London, in 2024.

But capturing data and feedback from social housing tenants is notoriously tricky. This can be due to the range of ways tenants prefer to communicate (from digital tools to landlines, physical post and in-person) as well as limited willingness to engage with authorities. This means that tenant perspectives are frequently unheard.

As customers, if we purchase a product and something is wrong, we know we have consumer rights and can have the complaint acted upon. The social housing sector is different. It has become increasingly stigmatised, resulting in areas of social housing being associated with higher crime rates, social deprivation and inequality, mental health issues and addiction.

Consequently, social housing tenants include vulnerable people on low incomes, who often experience digital inequality and less agency and control over their home environment. They rely on social housing stock availability and on landlords for the state of repair of their home.

While tenants can of course raise concerns over quality and maintenance with their housing provider, their voice has frequently gone unheard, as exemplified by the case of Awaab’s parents. But it shouldn’t be difficult to change this.

My colleague and I share a longstanding interest in social housing service performance. We wanted to understand how technology might support improvement in the sector and help guard against issues like the ones mentioned above.

Social housing is not typically associated with high technology, due to the financial constraints typical across the public sector, combined with a sometimes limited appetite for innovation. Yet the potential opportunities to use tech to improve the tenant experience appeared bountiful. Or at least, that’s what we thought.

Our research was designed to explore how tenants’ future experiences of social housing might be improved through the application of technology. We collected data from 35 experts from global tech organisations, including Amazon Web Services, as well as organisations dealing with social housing policy, senior social housing leaders (chief executives, directors or heads of service), frontline staff and tenants.

While we weren’t surprised by the broad improvement areas identified (around property standards, service delivery, integration of technology and empowerment), we did not expect that so many of the issues could be solved with low-tech (or even no-tech) solutions.

We used the Delphi method, which is a way of getting an overall picture of the future by aggregating responses from experts in different disciplines. We asked how each expert thought the “tenant of the future” might look.

In our findings, it emerged that they believed customers (that is to say, tenants) will have higher expectations in a number of areas associated with their housing.

1. Property standards

This emphasised the need for decent homes. This means social housing organisations and landlords being more aware of the quality of their properties and, in particular, paying greater attention to insulation to help with the cost of living.

2. Human-centred services

This would emphasise the importance of a contact model where tenants can raise concerns or complaints face to face through a designated housing officer. This theme also suggested that re-evaluating the core purpose of social housing would be helpful, including the role of and contribution to the wider community.

For example, respondents suggested increasing levels of community engagement by involving tenants in decision making. This would not only increase their agency, but also help to reduce stigma and stereotypes around social housing. This is an area where low or no-tech solutions are possible. One respondent said: “Whilst digital can yield massive improvements to service delivery, it should not be a replacement for … conversations with tenants, including face-to-face engagement.”

3. Making use of technology

While we expected demands in this area to be high, suggestions were in fact surprisingly modest. Respondents suggested things like online forms or live chat functions, and the use of smart devices to reduce energy consumption, detect mould or monitor things like boilers, for example.

4. Tenant empowerment

Collecting feedback allows landlords to understand tenants’ needs and work with them to develop a more customer-centred approach to social housing.

Damp and mouldy property is one of the biggest issues in social housing. epiximages/Shutterstock

Realisation of these humble findings doesn’t feel unattainable or spectacularly unaffordable, yet history has shown us that the sector has struggled to overcome stigma and prejudice to effect change.

So what could be done? The government is moving to build new homes at speed. While this will improve availability of housing stock nationally, it won’t address issues around the quality of existing stock without substantial investment. Greater transparency around the quality of social housing is vital, alongside more robust reporting and repair processes.

While we don’t have all the answers, the importance of direct personal contact that we uncovered in our research actually feels quite heartwarming, giving the sense that tenants’ views and concerns actually matter.

Ensuring personal contact points between tenant and social housing provider should be a straightforward and affordable allocation of existing resources. This isn’t too much to ask and is definitely not rocket science.

Nicky Shaw, Senior Lecturer in Operations Management. Leeds University Business School, University of Leeds and Simon Williams, Associate Faculty, Leeds University Business School, University of Leeds

This article is republished from The Conversation under a Creative Commons license. Read the original article.