A shipyard is, by definition, a sealed surface: asphalt, concrete and steel. These materials absorb solar radiation all day long and release it back as heat — the urban heat island effect, felt by the people who work there.
In November 2022 we planted the first Biodiversity Island in an industrial setting in Portugal at the Lisnave shipyard, in Mitrena, Setúbal: 150 native trees and shrubs across roughly 50 m², using the Miyawaki method. 45 months have passed. In August we returned to measure.
The measurements
All readings were taken on 13 August 2026, at midday, with an infrared thermometer, within the same time window and metres apart.
Asphalt in full sun — 39.2 °C
Ship hull under repair — 37.7 °C
Inside the MiniForest — 28.0 °C
That is an 11.2 °C difference between asphalt and the inside of the vegetation, in the same place at the same hour. Not an estimate, not a projection: a measurement.
Why vegetation cools
A dense patch of native vegetation with a closed canopy works in three ways at once. It intercepts solar radiation before it reaches the ground, it evapotranspires — leaves release water vapour, which consumes energy and lowers air temperature — and it keeps the soil covered and moist, preventing heat from building up in the substrate.
The result is a microclimate. It does not cool the whole shipyard, but it creates a volume of cooler air where there used to be nothing but a reflecting surface.
Temperature is the easiest thing to measure
At 45 months, the Lisnave island no longer behaves like a plantation: it behaves like an ecosystem. The canopy has closed, the soil has leaf litter, and where there was sand and asphalt there are now insects, spiders and birds.
Biodiversity is harder to reduce to a single number than temperature, but it is the more important indicator. Temperature is simply what a handheld instrument can capture.
Nature-based solutions as infrastructure
This data matters beyond the project itself. It shows that nature-based solutions are not decoration in an industrial space — they are thermal infrastructure, with a measurable effect on the comfort of the people working on site.
And they are replicable. Any shipyard, factory, school or business park with an unused patch of land can have an island.
The next island
In November 2026 we plant the next island at Escola Sant'Lago, in Setúbal, again funded by Lisnave. It will be the fourth island the company has supported: two inside the shipyard and two in schools in the municipality.
To measure is to care.
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