Plants don't make a building green

No.123 — Read old posts here.
Reading Time: 5 minutes

Somewhere along the way,
sustainability became a colour.
You would have guessed it by now.
Colour green.

Search for "sustainable architecture" today.
You'll get a page of glass towers wearing plants.

Concrete underneath.
Steel inside.
Air conditioning running all summer.
And a fringe of green hanging off every balcony.

Last week, the architectural historian Barnabas Calder wrote a line in Dezeen that we haven't been able to put down.

We read it and laughed.
Then we stopped laughing.
Because we used to do exactly this.

The confession

Before Tiny Farm Lab,
I worked in a corporate architecture office.
We were very good at green.

We drew planters into eleventh-floor balconies.
We compared mesh systems:
GI, stainless, powder-coated, cable net,
hunting for the one a creeper would actually climb.

We wrapped whole elevations in bougainvillea,
in render. We won presentations with it.

Nobody in that room was lying.
We believed it.

We believed that if enough green crept over the facade,
the building underneath would somehow be forgiven.

It wasn't.
The concrete was still concrete.
The glass still baked.
The AC still ran.

What is plant-washing?

It's when greenery stops being a component and becomes the argument.

The building is designed the usual way:
deep plan, sealed glass, mechanical everything,
and then vegetation is applied at the end.

Like a garnish.

Why does it keep changing its name?

Because the last word got caught.

"Greenwashing" was named and shamed,
so the industry moved on.

Now the same balcony planter arrives dressed as:

• biophilic design

• living wall

• green façade

• vertical forest

• bioponic wall - hydroponics, on a wall, with pumps and nutrient dosing

• bioclimatic tower

• forest city

Some of these are real ideas backed by real research.

Biophilia came from the biologist E.O. Wilson,
the idea that we carry an inherited
need to be near living things.

Stephen Kellert turned it into design principles:
light, air, prospect and refuge,
natural materials, water,
the seasons showing up indoors.

Notice how little of that requires a planter.

But "biophilic" sells better than
"we put the windows in the right place."

A word invented to reconnect people with life
now sells sealed boxes with foliage stapled on,
at a higher rate per square foot.

So what's actually wrong with it?

One.
The plants cost carbon long before they absorb any.

A facade that carries soil, trees and water has to carry weight.

Balconies get deeper.
Slabs get thicker.
Structure grows.

Milan's Bosco Verticale is the most celebrated
vertical forest in the world:
two towers, around 800 trees, 20,000 plants.

One analysis argues its structure is
roughly twice as heavy as a conventional building,
and so carries roughly twice the embodied carbon.

Cement is already around 8% of global emissions.
Buildings and construction together, about 37%.

You cannot plant your way out of that arithmetic.

Two.
The garden becomes an appliance.

A tree in the ground drinks rain.

A tree on the eleventh floor drinks pumped,
filtered, fertilised, computer-scheduled water.

Drip lines.
Sensors.
A plant room.
Nutrient dosing.
Replacement cycles.
A crane for the ones that die.

That is not nature returning to the city.
That is a machine wearing leaves.

Three.
It usually dies.

This is the part nobody photographs.

Look at our own cities.
Crores allocated for vertical gardens
on flyover pillars in Delhi and Mumbai.
Ribbons cut.

Then, a couple of seasons later, brown felt panels and dry drip pipes in Navi Mumbai, residents were complaining publicly about gardens that had shrivelled beside the railway station.

A wall of plants is not a wall.
It is a subscription.

Stop paying,
and it becomes litter.

Four.
And the dangerous one:
it buys permission.

The more convincingly a harmful building looks green,
the more harm the picture does.

Because it teaches an entire generation
what "sustainable" looks like:
tall, new, concrete, air-conditioned.
With leaves.

But aren't plants good?

Of course they are.

Shade is real.
A creeper on a west wall genuinely cools it.
A courtyard tree can drop the temperature around it.
Food on your roof is food.

What isn't real is the claim that a few plants clean your air.

That belief traces back to a 1989 NASA experiment run inside sealed chambers. A 2019 review of decades of studies found that ordinary ventilation does almost all of the work. To match those chamber results at home, you'd need something in the range of ten to a thousand plants per square metre.

Or you could open a window.
The problem was never the plant.
The problem is the plant being asked to do the building's job.

So what makes a building actually green?

The boring things.
The invisible things.

Not building at all,
where that's possible.
Reusing what already stands.
Building small.

Orientation.
Shade.
Cross ventilation.
Thermal mass.
A roof that overhangs its walls.

Materials from a few kilometres away,
not a few continents.
Hands that live nearby.
A building its own residents can repair.
And when it finally ends,
one that returns to the ground it came from.

None of this photographs well.

That's exactly the problem.
A camera cannot see a wall that never needed cooling.

One question to carry with you

Next time you see a tower with a forest on it,
try this.

Take the plants away.

What's left?

If what's left is honest, the plants are a gift.
If what's left needs the plants to be forgiven,
you're looking at a garnish.

Green isn't a colour you apply at the end.

It's a decision you make before the first brick.

Have you seen plant-washing near you?

Reply to this email with a photo — the dead vertical garden on your metro pillar, the empty planters on your office facade.

Love and light,
Raghav and Ansh

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