Concept: The Green Cocoon: A Pergola-like Trellis to Shade Hot Baking Roads with Lush Green Foliage

Roads and carparks can get inhumanely hot in summer. These plug-n-play green shading modules can be installed over any road or car park to reduce the ever-increasing crisis of urban heat.

Katie Patrick | Action Designer
Urban Canopy


The Green Cocoon: Easy-to-install shading pergolas for car parks and roads.

Hello World Labs has come with a great idea to cool cities down in the increasingly hot days of summer. It’s called the Green Cocoon — a green vegetation cover that shades roads and carparks. The Green Cocoon is a a set of modular vertical poles, horizontal spans, planters, and living plants that fit together with the ease of IKEA furniture. The Green Cocoon can be installed over spans of public roads with about the same infrastructure cost as installing a sign pole. Once the vertical and horizontal beams have been installed, pre-grown vines are planted in the planter units and encouraged to grow over the Green Cocoon structure. Within a short time, the foliage will cover the structure, and the road or parking lot will be “cocooned” in lush green foliage. It will prevent the immediate area from heating up to astronomical temperatures on hot days, and will create a beautiful urban feature for locals and visitors to love. See below:

After: Artist’s rendering of a Green Cocoon installed on the main street of Flint, MI.
Before: Main St. in Flint, MI with no Green Cocoon.

Inspiration — green shade structures

Green shade structures have already been used many times in beautiful and environmentally beneficial applications all over the world. However, existing ones have all been for residential or small-scale applications, and have only been used to cover paths or narrow alleys. But they don’t need to stay that way! We can reinvent the concept of living shade structures to apply to large commercial and civic developments.

Living green shade structures around the world. They’ve been small so far, but they could be more substantial.

Why we need The Green Cocoon— the urban heat crisis is real

Cities are getting hotter than ever. The vast amounts of asphalt and concrete used in cities stores the sun’s heat and creates what’s called an urban heat island — which means your city may be 10F degrees hotter than nearby parks and suburbs. You can easily see, in thermal images taken of cities on hot days, that one of the major culprits is roads. The black asphalt used on roads and car parks heats up like a frying pan, and can sometimes top 200F degrees on a hot day! Read a full article on the urban heat crisis here.

In this thermal image you can see many of the very hot surfaces, shown in red, are roads.
The urban heat island: the concrete and asphalt in cities absorb heat making them up to 10C hotter than surrounding areas. Red color indicates highest temperatures, blue the lowest.

This Urban heat causes all sorts of serious problems. High summer temperatures cause thousands of air conditioning units to be turned on at the same time. This demand creates a huge spike in the electricity grid, requiring additional power plants to be fired up to cater to everyone’s AC. This demand is so high that in New York City, it actually doubles the total demand on the grid during the summer.

Electricity demand over 24 hours by season in NYC: Summertime nearly doubles the demand on the grid. Source: 2017 Power Trends Report, New York Independent Systems Operator

Urban heat is also a serious health problem. Every heat wave leaves a wave of mortality in its wake from heat stroke, as well as an average of an additional 30,000 hospital admissions for heat-induced illness.

Urban heat also worsens air pollution by accelerating the chemical reactions that create smog.

Urban heat even increases the rate of violent crime and rape.

Read a full article on the many dimensions of the urban heat crisis here.

But the good news is that vegetation (grass, trees, foliage etc.) is remarkably good at near-nullifying the heat-trapping powers of asphalt. When we can shade these hot, dark surfaces with a tree or vine, their temperature-raising powers mostly dissipate.

Why we need more green space — it’s a health imperative

Many studies show the indisputable health benefits of green space.

The most elegant and delightful finding is simply that green spaces makes us happier:

“Having access to even small green spaces can reduce symptoms of depression for people who live near them. The impact was strongest for residents of poorer neighborhoods — they showed at least a 27.5 percent reduction in the prevalence of depression.” — Source: Effect of Greening Vacant Land on Mental Health of Community-Dwelling Adults

Seeing a view of nature, or even a just a photograph of a natural setting leads to people taking less pain medication after surgery:

“Patients exposed to nature images were significantly more likely to switch from strong analgesics to weaker painkillers during their recovery than patients in the other conditions — indicating that the nature images influenced patients’ postoperative pain.” — Source: Pain in its Environmental Context: Implications for Designing Environments to Enhance Pain Control

More green spaces and trees also reduces crime:

“This systematic literature review demonstrated overwhelmingly positive associations between urban green space and decreased violence and crime.” — Source: Green Space, Violence, and Crime: A Systematic Review

Looking at a green roof for 40 seconds lowers increases concentration:

“Participants who briefly viewed the green roof made significantly lower omission errors, and showed more consistent responding to the task compared to participants who viewed the concrete roof.” — Source: 40-second green roof views sustain attention: The role of micro-breaks in attention restoration

Green space is good for children’s brains:

“Children who attended schools with higher outdoor greenspace had a greater increase in working memory and a greater reduction in inattentiveness than children who attended schools with less surrounding greenness.” — Source: Green Spaces Influence the Cognitive Development in Children

“Primary schoolchildren who have been raised in homes surrounded by more greenspace tend to present with larger volumes of white and grey matter in certain areas of the brain.” — Source: Being Raised in Greener Neighborhoods May Have Beneficial Effects on Brain Development

Trees and plants also absorb air pollution:

“It was found that air samples taken from sites with less green space frequently had high concentrations of all fractions of aerosolized particulates than other sites, whilst sites with high proximal green space had lower particulates, even when vehicular traffic was taken into account.” — Source: Does urban forestry have a quantitative effect on ambient air quality in an urban environment?

Green space encourages people to walk and bike, which makes them healthier:

“Recent estimates show that physical inactivity, linked to poor walkability and lack of access to recreational areas, accounts for 3.3% of global deaths.” — Source: World Heath Organization

Our Vision

Imagine exciting, vibrant, and healthy cities thick with thriving vegetation. We’ve seen a rise in the green wall and green roof installations recently. But there is more we can do with greenery and with all the urban spaces that aren’t roofs and walls. Imagine an entire city that was draped in an urban canopy of foliage! It could be the most beautiful city on earth. See below:

The future of cities: covered in foliage. Artists’ impressions.

What The Green Cocoon includes

Cities can order modules of poles and arches. We size the parts to fit the requirements of the space, and choose fast-growing vine plants to suit the location. Customers receive a kit including the following:

  • Vertical poles
  • Horizontal spans
  • Connectors
  • Planter units
  • Soil for planters
  • Plants
  • Watering and drainage plan
  • Ongoing maintenance plan

Why The Green Cocoon is a good idea

  • It increases mental health of nearby residents and workers.
  • Cuts down peak load during summer by cooling the surrounding buildings.
  • Provides a tourist attraction, similar to the New York High Line.
  • Helps to filter air pollution.
  • May decrease crime.
  • Increases property values of nearby and adjacent buildings.
  • Propels economic, community, and cultural development in and around The Green Cocoon.
  • Increases the desirability and livability of the city as a whole.
  • Provides international positive press coverage and social media activity about the location.
  • More cost effective than competing car park shade coverings.

Call to action

Interested in getting The Green Cocoon installed in your city or campus? Hello World Labs can build it for you. Email our founder Katie Patrick at kp[at] to arrange a proposal. We’d love to build this concept for you!

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Katie Patrick | Action Designer
Urban Canopy

Environmental Engineer | Author of How to Save the World | Learn climate action design and how to gamify sustainability at