Passive Thermal Comfort Strategies in Residential Projects

Passive Thermal Comfort Strategies in Residential Projects

ArchDaily‘s Green dealt with Passive Thermal Comfort Strategies in Residential Projects. It is well informed regarding today’s main concerns of green building and is by Camilla Ghisleni and translated by Tarsila Duduch.

The picture above is of ArchDaily’s previous article on the Middle East: The Latest Architecture and News. Its caption is GOLD: Eco-Techno Park: Green building showcase and enterprise hub. Image Courtesy of Holcim Foundation.

This article is sponsored by Saint-Gobain

Passive Thermal Comfort Strategies in Residential Projects

Passive Thermal Comfort Strategies in Residential Projects, The House of Silence / Natura Futura Arquitectura © Lorena Darquea
The House of Silence / Natura Futura Arquitectura © Lorena Darquea

There was a time when people appreciated self-contained architecture, in which the building envelope would not function as a moderator between the climate outside and the interior environment but rather as an inert and independent barrier. Countless mechanical devices and electrical ventilation, heating, and cooling equipment. A real machine.

Today, architects are increasingly concerned with the interaction between architecture and the environment in which it is inserted, thus assuming responsibility for the thermal comfort of interior spaces, using design strategies for natural climate control.

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As a result, the design process involves more and more strategies called passive systems, which are mechanisms to naturally moderate temperature, to achieve harmony between the natural and the built environment, taking into consideration the particularities of each space, such as local micro-climate and its natural resources.

Although these strategies may vary considerably depending on the location of the project, there are a few basic principles that should always be followed to ensure the achievement of passive systems. In addition to the indispensable role of natural ventilation and lighting, passive measures also include the use of appropriate materials that can contribute to thermal mass, as well as specific design elements, such as indoor greenery and reflecting pools, among others.

To better understand the main passive design strategies for thermal comfort, here are some residential projects that demonstrate their application.

Natural ventilation is one of the most common passive design solutions and is used to move fresh air through the interior spaces thanks to air pressure variations. In cross ventilation, for example, by placing the openings on opposite sides of the room, the pressure difference promotes airflow, as is the case of the Lee House, designed by Marcio Kogan and Eduardo Glycerio, in which large sliding doors lower the temperature of the main living area, or in the FVB House with its red wooden lattices, allowing air to circulate throughout the residence.

FVB House / Claudia Haguiara Arquitetura © Christian Maldonado
FVB House / Claudia Haguiara Arquitetura © Christian Maldonado

Still on the subject of ventilation, one can also take advantage of the stack effect in which the warmer and denser air rises and the cooler air descends. In this case, double-height ceilings are used to favor this air exchange, as seen in the Sloth’s House in Guarujá, São Paulo, which also features a combination of great lighting, cross-ventilation, and requires no air conditioning.

Sloth's House / Nautilo Arquitetura & Gerenciamento © Alessandro Guimarães
Sloth’s House / Nautilo Arquitetura & Gerenciamento © Alessandro Guimarães

Furthermore, the use of interior courtyards is a century-old design strategy that contributes towards the passive cooling of buildings, such as the Infiltrated Patio House, built in the hot climate of Mérida, Mexico, or the House of Silence and the House Among Trees, both in Ecuador, one featuring a partially covered courtyard with little vegetation, the other a fully open courtyard with large plants.

House Among Trees / El Sindicato Arquitectura © Andrés Villota
House Among Trees / El Sindicato Arquitectura © Andrés Villota

When it comes to natural lighting, it is important to also pay attention to shading, aside from the basic principle of large sunlit surfaces for cold climates. A well-designed sunscreen should control solar gain in the hottest seasons without blocking it during the winter or interfering with the entrance of natural daylight. For this purpose, many design elements can be employed, the most popular of which is the brise-soleil, as used in the Boipeba House, made of wooden slats, or in the Soul Garden House, with metal perforated panels.

Boipeba House / daarchitectes © Michel Rey Photographe
Boipeba House / daarchitectes © Michel Rey Photographe

The Cobogós, as seen in the Lima House or the L106 House, two projects that are an ocean apart but in very similar climates, are a genuine Brazilian invention used very often because they allow airflow while preventing solar radiation.

L106 House / Pereira Miguel Arquitectos © Fernando Guerra | FG+SG
L106 House / Pereira Miguel Arquitectos © Fernando Guerra | FG+SG

Moreover, in the history of Brazilian buildings, we can also see the remarkable use of verandas and large eaves, illustrated here by an architectural classic, Lina Bo Bardi‘s Valéria Cirell House, enclosed by a cozy veranda originally covered with straw.

AD Classics: Valéria Cirell House / Lina Bo Bardi (2010). Image © Pedro Vannucchi
AD Classics: Valéria Cirell House / Lina Bo Bardi (2010). Image © Pedro Vannucchi

Building materials are also fundamental when it comes to thermal comfort through passive strategies. For buildings located in very hot climates, some materials can help in the house’s “transpiration” and also serve as a thermal barrier that prevents solar gains. As for buildings in colder climates, they can increase thermal inertia by retaining heat and releasing it during the night. Some materials that have high thermal capacity are concrete, brick, solid clay, and stone, found in various projects such as the Half Buried House, which uses the soil to create appropriate thermal inertia for the local climate, and the Family House in La Pereda, both in Spain.

Half Buried House / eneseis arquitectura. © Andrés Flasjzer
Half Buried House / eneseis arquitectura. © Andrés Flasjzer

Water is one of the oldest and most efficient methods of passively cooling a building, especially in dry climates. Evaporative cooling is a process of removing heat from the environment or material through water evaporation. An example of this is the Nivaldo Borges Residence, by Lelé, another emblematic work of Brazilian architecture, where gardens and a striking reflecting pool permeate the private living area and study room, and a more contemporary example is the Bacopari House, by UNA Arquitetos, in São Paulo.

AD Classics: Nivaldo Borges Residence / João Filgueiras Lima. © Joana França
AD Classics: Nivaldo Borges Residence / João Filgueiras Lima. © Joana França

Finally, we must not overlook the impact of vegetation, both indoors and outdoors, as it plays an important role in reducing solar radiation and achieving a microclimate that provides better thermal comfort conditions. Among many examples that use vegetation as a design strategy, we have here the MM Tropical House, which, as the name implies, is situated in a tropical environment in Southeast Asia, and therefore uses vegetation as a tool to minimize solar gain.

MM Tropical Suburb Town House / MM++ architects. © Hiroyuki Oki
MM Tropical Suburb Town House / MM++ architects. © Hiroyuki Oki

Some projects also feature vegetation on the rooftop which provides greater thermal comfort inside the building, thus reducing energy consumption for heating or cooling the environments. The LLP House, in Spain, is an interesting example because, to maximize the environmental and thermal performances, following the clients’ request to create a passive house, the construction features not only a roof garden but also a compact built environment, solar capturing and protection, thermal resistance, and cross ventilation.

House LLP / Alventosa Morell Arquitectes © Adrià Goula
House LLP / Alventosa Morell Arquitectes © Adrià Goula

The search for a building with high levels of thermal comfort through passive design requires architectural creativity and ingenuity, often thinking of new ways to apply different materials or revisiting vernacular techniques. However, to correctly execute these design strategies, it is imperative to be familiar with the particularities of the building site, understanding the orientation of the sun and the direction of the winds. Moreover, successful projects usually combine different strategies to achieve the best thermal comfort conditions.

Related articles
How to Design for Optimal Thermal Comfort (And Why it Matters)
Cross Ventilation, the Chimney Effect and Other Concepts of Natural Ventilation

Jordan aims for Green with a 10-million tree campaign

Jordan aims for Green with a 10-million tree campaign

The picture above is of Jordan times.

Land degradation affects the vast majority of the MENA region, mainly through desertification. However, as more land becomes bereft of life across the region because of climate change, deforestation ensuing for years on end, the United Nations some years back, warned that a rise in socio-political instability could lead to dwindling resources. All across the MENA region, as the ground is getting hotter, drier and deadlier, it would be more challenging to tackle practical measures that can help to salvage and, in some cases, revitalise the degraded resources that remain. For instance, desert country Jordan aims for Green with a 10-million tree campaign. Here are Mussa Hattar’s explanations.

Desert country Jordan aims for Green with 10-million tree campaign

Jordan aims for Green with a 10-million tree campaign
Eucalyptus and carob saplings are planted near the forest of Kufranjah, north of Jordan's capital Amman, part of a reforestation
Eucalyptus and carob saplings are planted near the forest of Kufranjah, north of Jordan’s capital Amman, part of a reforestation effort that aims to reach 10 million trees in 10 years

On a bare hill in Jordan’s verdant Ajloun region, dozens of people plant saplings as part of a reforestation effort that aims to reach 10 million trees in 10 years.

“The trees in our region are beautiful,” says 11-year-old Mohammed al-Ananza, helping his father Mustafa plant a carob sapling.

“It’s a real shame that we have lost so many to fires… We should work together to protect them,” he says as they work near the Kufranjah forest north of the capital Amman.

Forests make up only one percent of the desert kingdom’s territory, according to the agriculture ministry, though Jordan also has an estimated 23 million orchard trees, half of them olives.

Forest fires strike almost every year in the Middle Eastern country due to high summer temperatures, in a trend scientists expect to intensify with climate change.

The blazes are often started by picnickers’ barbeques or carelessly discarded cigarettes.

There were 499 fires in wood and forest areas last year alone, according to the agriculture ministry.

“We must make up for what has been lost in the fires,” said Belal Qtishat, head of the nature protection department at the environment ministry.

“It’s the only way to fight desertification and climate change and to protect biodiversity.”

Jordan aims for Green with a 10-million tree campaign
The tree planting campaign began in Kufranjah, which one official described as "Jordan's lungs", to make up for what h
The tree planting campaign began in Kufranjah, which one official described as “Jordan’s lungs”, to make up for what has been lost in fires


Mahmoud al-Ananza watched on as his grandson and son got to work on the hill in Kufranjah.

The family has volunteered but agriculture and environment ministry employees were also among the 150 people in charge of planting 30,000 trees in the area.

“I was born here and I can tell you that if you plant cypress trees, eucalypts, olives, carob or oak, they will grow on their own,” the man in his 70s said, wearing a traditional red-and-while keffiyeh scarf.

The programme focuses on species that, after the initial phase of taking root, can survive without a lot of additional water.

Mohamed Daoudia, agriculture minister at the time of the project’s launch last month, said fires were the biggest problem for Jordan’s wooded areas.

“Illegal tree felling only represents one percent of the damage to forests,” he told AFP.

In October, 50 hectares (over 120 acres) of olive and forest trees burnt in the Ajloun region, while a year earlier in Jerash province, 80 hectares went up in flames.

Qtishat, of the environment ministry, said the reforestation project aimed to rehabilitate only “the regions fit for doing so”.

“We don’t plan to cover the whole kingdom with trees because each part of the country has its own special features,” he said.

Jordan aims for Green with a 10-million tree campaign
Jordanian officials hope the tree-planting programme will help to fight desertification and climate change, as well as protect b
Jordanian officials hope the tree-planting programme will help to fight desertification and climate change, as well as protect biodiversity

Benefits for bees

The aim of the first stage is to create forests in Karak and Tafila provinces south of the capital, planting in each area 30,000 commonly found trees like eucalyptus, jujube and carob.

The campaign began in Kufranjah, which Qtishat described as “Jordan’s lungs”.

The kingdom also plans to work on fire prevention by setting up monitoring posts and patrols, providing its civil defence with specialised vehicles and carrying out forest surveillance using drones.

Former minister Daoudia described the reforestation programme as both “ambitious and realistic”.

He said results would be seen in the next four to five years, and that the greening campaign would also benefit bees and honey production.

Jordan produces an average of 250 tonnes of honey a year.

“Our nurseries produce 2.5 million forest trees a year and 500,000 fruit trees. So in theory, we could plant 10 million trees in four years,” Daoudia said.

“But we decided on 10 years in order to do the job well.”

Explore furtherForests’ long-term capacity to store carbon is dropping in regions with extreme annual fires

Sustainable water management key to scaling up bioenergy production

Sustainable water management key to scaling up bioenergy production

International Institute for Applied Systems Analysis elaborates on how Sustainable water management key to scaling up bioenergy production.

This is happening as part of Bioenergy technologies to have significant potential to scale up by 2050. The peoples, governments, and businesses will have to achieve this sustainability and do it; these have to readjust some of their habits. Anyway here is :

Sustainable water management key to scaling up bioenergy production

To avoid a substantial increase in water scarcity, biomass plantations for energy production need sustainable water management, a new study shows.

The picture above is for illustration and is of Divdiscourse‘s Limiting water stress risks.

Bioenergy is frequently considered one of the options to reduce greenhouse gases for achieving the Paris climate goals, especially if combined with capturing the CO2 from biomass power plants and storing it underground. Growing large-scale bioenergy plantations worldwide, however, does not just require land, but also considerable amounts of freshwater for irrigation – which can be at odds with respecting Earth’s Planetary Boundaries. An international team of scientists has used their most detailed computer simulations to date to calculate how much additional water stress could result for people worldwide in a scenario of conventional irrigation and one of sustainable freshwater use.

“Irrigation of future biomass plantations for energy production without sustainable water management, combined with population growth, could double both the global area and the number of people experiencing severe water stress by the end of the century, according to our computer simulations,” says lead author Fabian Stenzel from the Potsdam Institute for Climate Impact Research (PIK), who developed the research idea for this study while participating in the Young Scientists Summer Program (YSSP) – IIASA’s flagship initiative for mentoring young scientists. “However, sustainable water management could almost halve the additional water stress compared to another analyzed scenario of strong climate change unmitigated by bioenergy production.”

Both political regulation and on-farm improvements needed

“Sustainable water management means both political regulation – such as pricing or water allocation schemes – to reduce the amounts of water taken from rivers as well as on-farm improvements to make more efficient use of the water,” explains study coauthor Sylvia Tramberend, a researcher in the IIASA Water Security Research Group. “This could include cisterns for rainwater collection or mulching to reduce evaporation. Moreover, sustainable water management includes the preservation of reliable river flows to ensure undisturbed ecosystems in and alongside rivers. Up- and downstream river management may in fact require international cooperation calling for more transboundary river management, as well as between different water users – that’s the challenge ahead for integrated water resource management.”

Largely unmitigated global warming together with population growth would increase the number of people under water stress by about 80% in the simulations. Enhanced use of bioenergy with carbon capture and storage could limit climate change: When plants grow, they take up CO2 from the air and build it into their trunks, twigs, and leaves. If this biomass is burned in power plants and the CO2 is captured from the exhausts and stored underground (carbon capture and storage (CCS)), this can eventually help reduce the amount of greenhouse gases in our atmosphere – scientists call this ‘negative emissions’.

In many scenarios, these are seen as necessary for meeting ambitious climate mitigation targets if direct emission reductions proceed too slowly, and to balance any remaining greenhouse gas emissions that are difficult or impossible to reduce, for instance potentially in aviation, certain types of industry, or in livestock production.

Water scarcity remains a huge challenge

“According to existing scenarios, biomass plantations could increase by up to 6 million km2 if global warming is to be limited to 1.5°C by the end of the century, the more ambitious of the two temperature targets of the Paris Agreement,” says coauthor Dieter Gerten from PIK. “We used these scenario inputs to run simulations in our high resolution global vegetation and water balance model to explore the freshwater implications. While substantial irrigation implied in a bioenergy plus CCS scenario including population growth suggests a 100% increase in the number of people facing water stress, combining it with sustainable water management brings the number down to 60%. This, of course, is still an increase, so challenging tradeoffs are on the table.”

Regions that already suffer from water stress today would be most affected in the climate change scenario, like the Mediterranean, the Middle East, northeastern China, South-East and southern West Africa. In the bioenergy plus CCS scenario without sustainable water management, high water stress extends to some otherwise unaffected regions, like eastern Brazil and large parts of Sub-Saharan Africa. Here, large biomass plantation areas in need of irrigation are assumed in the scenario analyzed.

Sustainable Development Goals and Planetary Boundaries must be taken into account

Climate mitigation is one of the Sustainable Development Goals (SDGs) the world has agreed to achieve. The water–energy–environment nexus studied in this research highlights that pathways to sustainability must consider all affected SDGs.  

“The numbers show that either way, sustainable water management is a challenge to be addressed urgently,” says coauthor Wolfgang Lucht, head of PIK’s Earth System Analysis research department. “This new study confirms that measures currently considered to stabilize our climate, in this case bioenergy plus CCS, must take into account a number of further dimensions of our Earth system – water cycles are one of them. Risks and tradeoffs have to be carefully considered before launching large-scale policies that establish biomass markets and infrastructure. The concept of Planetary Boundaries considers the whole Earth system, including but not limited to climate. Particularly the integrity of our biosphere must be acknowledged to protect a safe operating space for humanity.”


Stenzel, F., Greve, P., Lucht, W., Tramberend, S., Wada, Y., Gerten, D. (2021). Irrigation of biomass plantations may globally increase water stress more than climate change. Nature Communications DOI: 10.1038/s41467-021-21640-3  

About IIASA:

The International Institute for Applied Systems Analysis (IIASA) is an international scientific institute that conducts research into the critical issues of global environmental, economic, technological, and social change that we face in the twenty-first century. Our findings provide valuable options to policymakers to shape the future of our changing world. IIASA is independent and funded by prestigious research funding agencies in Africa, the Americas, Asia, and Europe.

3 Reasons Construction Companies Need to Digitally Transform Now

3 Reasons Construction Companies Need to Digitally Transform Now

FORConstructionPROS explains how 3 Reasons Construction Companies Need to Digitally Transform Now.

As the pandemic continues to change the way businesses run, construction companies have begun to realize the importance of going digital. It is by Tom Stemm of Ryvit.

The need for digitization in construction has been made clear by the pandemic and by other industries that have successfully overcome their operational challenges through the introduction of digital products and services.

Digital transformation has been a key area of investment for businesses over the past decade and is expected to only continue. Even with the pandemic wreaking havoc on business spending worldwide, overall digital transformation spending was still forecasted to increase by 10% in 2020.

The construction industry has lagged behind other industries in this respect, being notoriously reliant on outdated technology and operating in deeply entrenched business silos. Despite this, there is still progress. The pandemic forced companies to innovate, and construction businesses that introduced safety and communication technologies are highly likely to keep them once the pandemic is over. It’s clear technology will continue to play a major role in transforming safety, communications and operations. 

Covid 19 Changes Here To Stay ProcoreProcore

How the Pandemic Increased the Need for Efficiency

Prior to COVID-19, construction companies were experiencing high demand and increasing revenues, despite their slow adoption of new technologies and a lack of digital maturity. Once the pandemic hit, this changed rapidly. The construction industry lost a total of $60.9 billion in GDP in the U.S. alone, with an estimated reduction to 6.5 million jobs, down from 7.64 million since February 2020. 

Furthermore, inefficient on-site workflows that relied on paper trails and outdated communication methods became even more difficult to work with once social distancing measures were implemented. As a result, businesses have been forced to look for digital solutions that can unlock new operational efficiencies and enable service delivery with reduced manpower. 

Why are Construction Companies Struggling to Innovate?

The need for digitization in construction has been made clear by the pandemic and by other industries that have successfully overcome their operational challenges through the introduction of digital products and services. Construction companies, however, often work on projects with extremely different requirements. The processes and systems that are in place for one project have to be coordinated with a variety of contractors, subcontractors, suppliers, and business divisions. These projects are often one-offs and are rarely replicated. Consequently, business leaders who might be enthusiastic about digital transformation might be unsure how to go about achieving it. 

3 Reasons Construction Companies Need to Digitally Transform Now

The gap between field and office workers is growing 

Construction operations have always been broken down into individually operating business divisions, and slower collaboration between divisions has caused a significant increase in lead time. The enforced necessity of remote work has only made communication between teams a greater challenge. 

Between offices, remote workers, contractors and suppliers, any on-site observations made regarding material quality, for instance, have to go through several communication channels before new materials can be procured. This communication chain can cause great confusion, delay delivery time and create animosity between contractors and employees. 

The introduction of a unified communication channel allows construction teams to increase collaboration, aligning the different stakeholders on the requirements and schedules of each project. A digital solution also allows communication to occur in real time. Many on-site employees still use physical paper forms to take notes while inspecting the site and communicating the information on the form can take time. An integrated communications platform keeps everyone up to date and reduces the time it takes for key information to cross business divisions.

Productivity and effectiveness are key to delivering results

Construction businesses tend to be entrenched in outdated processes that limit productivity. McKinsey reported that productivity growth in the construction industry has increased a mere 1% a year over the last 20 years. This lags behind counterparts in other industries, who are increasing productivity at almost three times the rate. This inefficiency is estimated to cost the global economy $1.6 trillion a year. 

Construction Productivity Costs Mckinley

With the demand for construction services increasing rapidly and the construction workforce aging to a large extent, efficiency and improved productivity can be the difference between an overwhelmed workforce and a satisfied clientele. McKinsey found that firms that introduced digital systems for procurement, supply-chain management, better on-site operations and increased automation had improved productivity 50% over firms that relied on analog solutions. 

Through the use of technologies such as AI, IoT and VR, construction businesses can modernize each stage of their operations from planning to execution. This reduces the amount of time spent revising designs, seeking approvals and calculating the resources needed for any changes in the project. 

There is an increased focus on health and safety

The pandemic has caused many people to pay more attention to health and safety standards in all types of workplaces. For construction businesses, this focus on safety and health is not new. Despite its efforts, according to the U.S. Bureau of Labor Statistics, the construction industry has one of the highest fatality rates, with 9.5 fatalities per 100,000 full-time equivalent workers. Construction companies are under pressure to minimize construction accidents by improving on-site safety and protection guidelines, and provide improved support to workers who need it. 

The introduction of technologies such as exoskeletons, AR glasses and wearable monitoring devices has made achieving higher safety standards possible. When technology works in tandem with production, it can increase on-site safety standards by reducing human error and improving response in case of an adverse event. When this technology is integrated, business leaders also have a holistic view of their operation and can identify potential safety problems early. 

Businesses and industries that transformed themselves early have displayed the benefits of adopting modern applications and systems. Technology has made improving safety standards, appealing to a new generation of workers and increasing operational efficiency, more achievable than ever before. Construction companies must transform and now is the time. 

Could plastic roads make for a smoother ride?

Could plastic roads make for a smoother ride?

The BBC‘s Could plastic roads make for a smoother ride? By Chermaine Lee is an eye-opener in one right way of ridding the World of those nasty tons of polymer derivatives that are encombering the World. When energy is transitioning from fossil fuels to renewables, it is more than reasonable to make fair use of that material. It would be even more useful if all those hydrocarbon related stranded assets have some usage in future infrastructural development. But that is another story.

From lower carbon emissions to fewer potholes, there are a number of benefits to building a layer of plastic into roads.

On a road into New Delhi, countless cars a day speed over tonnes of plastic bags, bottle tops and discarded polystyrene cups. In a single kilometre, a driver covers one tonne of plastic waste. But far from being an unpleasant journey through a sea of litter, this road is smooth and well-maintained – in fact the plastic that each driver passes over isn’t visible to the naked eye. It is simply a part of the road.

This road, stretching from New Delhi to nearby Meerut, was laid using a system developed by Rajagopalan Vasudevan, a professor of chemistry at the Thiagarajar College of Engineering in India, which replaces 10% of a road’s bitumen with repurposed plastic waste.

India has been leading the world in experimenting with plastic-tar roads since the early 2000s. But a growing number of countries are beginning to follow suit. From Ghana to the Netherlands, building plastic into roads and pathways is helping to save carbon emissions, keep plastic from the oceans and landfill, and improve the life-expectancy of the average road.

By 2040, there is set to be 1.3 billion tonnes of plastic in the environment globally. India alone already generates more than 3.3 million tonnes of plastic a year – which was one of the motivators behind Vasudevan’s system for incorporating waste into roads.

It has the benefit of being a very simple process, requiring little high-tech machinery. First, the shredded plastic waste is scattered onto an aggregate of crushed stones and sand before being heated to about 170C – hot enough to melt the waste. The melted plastics then coat the aggregate in a thin layer. Then heated bitumen is added on top, which helps to solidify the aggregate, and the mixture is complete.

Many different types of plastics can be added to the mix: carrier bags, disposable cups, hard-to-recycle multi-layer films and polyethylene and polypropylene foams have all found their way into India’s roads, and they don’t have to be sorted or cleaned before shredding.

As well as ensuring these plastics don’t go to landfill, incinerator or the ocean, there is some evidence that the plastic also helps the road function better. Adding plastic to roads appears to slow their deterioration and minimise potholes. The plastic content improves the surface’s flexibility, and after 10 years Vasudevan’s earliest plastic roads showed no signs of potholes. Though as many of these roads are still relatively young, their long-term durability remains to be tested.

By Vasudevan’s calculations, incorporating the waste plastic instead of incinerating it also saves three tonnes of carbon dioxide for every kilometre of road. And there are economic benefits too, with the incorporation of plastic resulting in savings of roughly $670 (£480) per kilometre of road.New roads in India built near large urban centres are mandated to use waste plastic in their construction (Credit: Getty Images)

New roads in India built near large urban centres are mandated to use waste plastic in their construction (Credit: Getty Images)

In 2015, the Indian government made it mandatory for plastic waste to be used in constructing roads near large cities of more than 500,000 people, after Vasudevan gave his patent for the system to the government for free. A single lane of ordinary road requires 10 tonnes of bitumen per kilometre, and with India laying thousands of kilometres of roads a year, the potential to put plastic waste to use quickly adds up. So far, 2,500km (1,560 miles) of these plastic-tar roads have been laid in the country.

“Plastic-tar road can withstand both heavy load and heavy traffic,” says Vasudevan. “[It is] not affected by rain or stagnated water.”

Similar projects have emerged around the world. The chemicals firm Dow has been implementing projects using polyethylene-rich recycled plastics in the US and Asia Pacific. The first in the UK was built in Scotland in 2019 by the plastic road builder MacRebur, which has laid plastic roads from Slovakia to South Africa.

MacRebur has also found that incorporating plastic improves roads’ flexibility, helping them cope better with expansion and contraction due to temperature changes, leading to fewer potholes – and where potholes do happen, filling them in with waste plastic otherwise destined for landfill is a quick fix. The UK government recently announced £1.6m for research on plastic roads to help fix and prevent potholes.The plastic that goes into roads would otherwise go to landfill or the incinerator (Credit: MacRebur)

The plastic that goes into roads would otherwise go to landfill or the incinerator (Credit: MacRebur)

In the Netherlands, PlasticRoad built the world’s first recycled-plastic cycle path in 2018, and recorded its millionth crossing in late May 2020. The company shredded, sorted and cleaned plastic waste collected locally, before extracting polypropylene from the mix – the kind of plastic typically found in festival mugs, cosmetics packaging, bottle caps and plastic straws.

Unlike the plastic-tar roads laid in India, the UK and elsewhere, PlasticRoad doesn’t use any bitumen at all. “[PlasticRoad] consists almost entirely of recycled plastic, with only a very thin layer of mineral aggregate on the top deck,” says Anna Koudstaal, the company’s co-founder.

Each square metre of the plastic cycle path incorporates more than 25kg of recycled plastic waste, which cuts carbon emission by up to 52% compared to manufacturing a conventional tile-paved bike path, Koudstaal says.

But once the plastic is inside a path or road – how do you make sure it stays there? Might the plastic content be worn down into microplastics that pollute soil, water and air?

Ordinary roads, tyres and car brakes are already known to be a major source of microplastic pollution. Koudstaal says that plastic-containing paths do not produce more microplastics than a traditional road, as users don’t come into direct contact with the plastic.Plastic bags can be hard to recycle, but they are an ideal ingredient for plastic in roads (Credit: Alamy)

Plastic bags can be hard to recycle, but they are an ideal ingredient for plastic in roads (Credit: Alamy)

The other potential point where microplastics could be released from the paths is from below: the paths are designed to allow rainwater to filter through them, trickling down through a drainage system beneath the path’s surface. But Koudstaal says microplastics are unlikely to leave this way either: “The bike paths include a filter that cleans out microplastics, and ensure rainwater infiltrates into the ground cleanly.”

Gurmel Ghataora, senior lecturer at the department of civil engineering at the University of Birmingham, agrees that using plastics in the lower surfaces of the road minimises the risk of generating additional microplastics. “It is inevitable that such particles may be generated [at surface level] due to traffic wear,” he says.

With India home to one of the world’s largest road networks, growing at a rate of nearly 10,000km of roads a year, the potential to put plastic waste to use is considerable. Though this technology is relatively new for India, and indeed the rest of the world, Vasudevan is confident that plastic roads will continue to gain popularity, not only for environmental reasons, but for their potential to make longer-lasting, more resilient roads.

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