The world's first farm-scraper

The world’s first farm-scraper gives new meaning to the idea of vertical farming.

Jian Mu tower

Some 4.4 billion of us live in cities, and that number is growing every day. Housing so many people is problematic. Traditional construction is damaging the environment and space is at an increasing premium. Feeding an expanding urban population in a nutritious and sustainable manner is, arguably, an even bigger challenge.

One solution could be for cities to produce more food themselves. This would reduce food miles and cities’ carbon footprints. But it would also require finding ways to increase urban agricultural land without making city living even more crowded. 

“There are roof gardens all over the world. But the problem is that this is usually very small scale – you can probably feed one family,” says Carlo Ratti, founding partner of CRA-Carlo Ratti Associati and director of the MIT Senseable City Lab. “Is there a way to look at new changes in hydroponic production and integrate them in the building environment so we can really produce scale?”

That is the challenge CRA hopes to address with its latest project – the Jian Mu Tower in city of Shenzhen in southern China. The 218 metre tower, spanning 51 levels, gives a whole new meaning to the term “vertical farming”, offering some 10,000 square metres of space for food production.

Dubbed as the first “farm-scraper” in the world, the building is designed to produce 270,000 kg of fresh produce per year. Fruit, vegetables, herbs and salad greens will be grown using an advanced soil-less farming technique known as aeroponics. Plant roots are suspended in the air, guaranteeing plenty of oxygen. Water and nutrients are then delivered via a fine mist spray, the dosage of which can be easily optimised with the use of an AI-supported “virtual agronomist”.

The system differs from traditional hydroponics, through which roots are placed in enriched water, the presence of nutrients and oxygen in which can be harder to monitor and control.

Farming without soil is seen as key to feeding a growing world population at a time when climate change and intensive farming are causing rapid loss of farmable soil. It is estimated that 1 per cent of topsoil is lost every year to erosion, largely caused by agriculture.1 If current levels of degradation continue, the world will run out of topsoil within 60 years, according to the United Nations.

Soil erosion infographic

In turn, the plants could help address the ecological footprint of the skyscraper and provide a new blueprint for greener buildings. That’s crucial in the fight against climate change because buildings account for 36 per cent of global energy use through their construction and operation. They are also responsible for nearly 40 per cent of energy-related carbon dioxide emissions.

One problem inhibiting urban sky scrapers is solar shading.

“When you have a tall building, a sky scraper, you need to shade from the sun,” notes Ratti.

In cities, the sun’s rays often reflect off the glass-covered facades of skyscrapers. This can lead to overheating (necessitating the use of energy-intensive air conditioning) and can also create glare on our ever-increasing number of screens, causing discomfort to the building’s users.

In the farm-scraper, by contrast, the plants will both absorb the sun’s rays for their own growth, while providing shade to the offices and shops which will populate the rest of the building.

On scale, such designs can make a big difference. Research shows that city temperatures are pushed up by the prevalence of heat-trapping surfaces, such as asphalt and concrete, and a lack of vegetation. That, in turn, increases morbidity and mortality.2

And the sun’s rays aren’t the only thing the farm will absorb. Afforestation, or growing more greenery, is key to reducing the levels of CO2 in the air and reducing the effects of climate change.

“You can get enough food to feed around 40,000 people and absorb around 20,000 kg of CO2 in a year,” Ratti says. “It’s a win-win for everybody.”

[1] "Dirt: The Erosion of Civilizations", D. R. Montgomery, 2012
[2] "Global urban population exposure to extreme heat", C. Tuholske et al, 2021