Tokyo office building turns tenant food waste into rooftop garden produce

Mitsui Fudosan Co., Ltd., Chugai Pharmaceutical Co., Ltd., Mandarin Oriental Tokyo and komham Inc. launched a rooftop garden project at the Mitsui No. 2 Building in Tokyo, closing the loop on food waste into compost to cultivate vegetables.

The project addresses urban food waste by collecting discarded ingredients and food scraps from Chugai Pharmaceutical’s employee cafe, KOM, and the Mandarin Oriental Tokyo hotel. The technology startup komham processes this organic matter using its Smart Compost machine, whose system breaks down organic waste efficiently and turn it into nutrient-rich compost.

Workers then apply the compost to the Mitsui No. 2 Building’s rooftop garden to grow various vegetables. Employees from the tenant companies participate in planting and harvesting the produce. The companies distribute the harvested vegetables to their internal cafeterias and allow employees to take them home. This creates a closed-loop resource cycle entirely within the premises.

Corporate sustainability efforts require practical implementation. This project brings environmental action directly to the workplace, an area where office workers often lack hands-on engagement. Mitsui Fudosan stated it aims to evolve office buildings from mere workplaces into spaces that generate new value through collaboration.