An organic food company has opened what it says is the world’s largest rooftop greenhouse atop the roofs of Tachen International and BrightonBest warehouses in Montreal, Canada.

The greenhouse spans 160,000 sq ft – roughly the size of three football fields, PHYS.org reports.

Lufa Farms is growing eggplants and tomatoes to “meet demand for locally sourced foods” in the center of Canada’s second-largest city.

“It is the fourth rooftop greenhouse the company has erected in the city,” according to PHYS.org.  “The first, built in 2011 at a cost of more than Can$2 million (US$1.5 million), broke new ground.”

Fully automated, the new greenhouse also has a water system that collects and reuses rainwater, resulting in savings of 90% compared to a traditional farm, PHYS.org reports.

“The advantage of being on a roof is that you recover a lot of energy from the bottom of the building,” allowing considerable savings in heating costs, company spokesman Thibault Sorret told AFP.

“We also put to use spaces that were until now completely unused.”

Lufa Farms, which employs 500 people, says it’s now able to feed almost 2% of Montreal with its greenhouses and partner farms.