Four Companies Launch Rooftop Farming Project Utilizing Food Waste: Creating a Closed-Loop Model from Composting to Cultivation and Utilization

Key Points of This Release

・Food waste from tenant companies and facilities is composted and used to grow vegetables on the rooftop farm of Mitsui Building No. 2. Harvested vegetables are utilized in employee cafeterias, establishing an in-building resource circulation model.

・Mitsui Fudosan, Chugai Pharmaceutical, Mandarin Oriental Tokyo, and komham have partnered to reduce food waste and promote resource circulation.

・Through harvesting experiences and other activities, the project enhances participants’ environmental awareness and strengthens collaboration among tenant companies.

Mitsui Fudosan Co., Ltd. (Headquarters: Chuo-ku, Tokyo; President & CEO: Shun Ueda; hereinafter “Mitsui Fudosan”), Chugai Pharmaceutical Co., Ltd. (Headquarters: Chuo-ku, Tokyo; President & CEO: Osamu Okuda; hereinafter “Chugai Pharmaceutical”), Mandarin Oriental Tokyo (Headquarters: Chuo-ku, Tokyo; Representative: David Kollas), and komham Inc. (Headquarters: Atsubetsu-ku, Sapporo, Hokkaido; CEO: Suno Nishiyama; hereinafter “komham”) have officially launched a full-scale rooftop farming project using compost derived from food waste at “Mitsui Building No. 2,” an office building operated by Mitsui Fudosan.

In this project, food waste generated at Chugai Pharmaceutical’s in-house café “KOM” and Mandarin Oriental Tokyo is collected and converted into compost using komham’s developed organic waste processor, “Smart Compost®.” The resulting compost is used to cultivate vegetables on the rooftop farm of Mitsui Building No. 2. The harvested vegetables are then used in employee cafeterias across the participating companies, aiming to establish a closed-loop system where resources circulate within the building, starting from food waste.

Amid growing interest in food waste reduction and resource circulation, businesses are increasingly expected to implement sustainable practices. However, office workers often lack accessible opportunities to engage in environmental activities. Mitsui Fudosan aims to transform office buildings from mere “workplaces” into spaces that create new value through collaboration with tenants and partners. Through this project, the company seeks to enhance participants’ environmental awareness, promote collaboration among tenant companies, and implement innovative sustainability initiatives in urban office buildings.

Photo: Employees from tenant companies planting seedlings and harvesting vegetables

Project Details

The project collects food waste from Chugai Pharmaceutical’s in-house café “KOM” and Mandarin Oriental Tokyo, converting it into compost using komham’s “Smart Compost®” organic waste processor.

The produced compost is used for vegetable cultivation on the rooftop farm, with opportunities provided for employees of tenant companies to participate in harvesting experiences. The harvested vegetables are used in tenant companies’ employee cafeterias or taken home by participants, aiming to establish a system where resources circulate within the building.

Additionally, the project serves as a platform for interaction among tenant companies, contributing to the creation of new added value within the office building.

Company Comments

[Chugai Pharmaceutical Co., Ltd.]

Environmental conservation is a key focus for our company, and fostering environmental awareness among each employee is also a critical objective. This experiential initiative provides a valuable opportunity for employees to experience environmental activities in their daily work, and we have received positive feedback from participants. We also find it highly meaningful that through collaboration with tenant companies and facilities, we can tangibly experience waste reduction and resource circulation within the office building.

[Mandarin Oriental Tokyo]

While we have previously worked on food waste reduction, this project allows us to discover new value by treating ingredients as recyclable resources. We find great significance in the circular process where previously discarded ingredients are reused as compost, grow into vegetables, and return to people’s hands. As a food-related business, we will continue contributing to the realization of a sustainable society.

[Mitsui Fudosan Co., Ltd.]

Mitsui Fudosan aims to transform office buildings beyond mere “workplaces” into spaces that create new value through collaboration with tenants and partners. This initiative creates an experiential opportunity for resource circulation, starting from the challenge of food waste and enabled by inter-company collaboration. We will continue contributing to a sustainable society through collaboration with tenant companies.

[komham Inc.]

Our mission is “improving living environments through microorganisms.” We have been researching and developing high-speed organic waste decomposition technology using our proprietary microbial consortium, “Komham.” We are delighted that the installation of “Smart Compost®” on the rooftop of Mitsui Building No. 2 has automated and streamlined the composting process, previously reliant on manual labor, contributing to stable resource circulation. Moving forward, we will continue supporting the further development of urban office building resource circulation models by utilizing data gathered from this project.

Sustainability at Mitsui Fudosan Group

The Mitsui Fudosan Group operates under the “&Mark” philosophy: “Continuously challenging to create new value through coexistence, co-living, and co-creation.” We view “social value creation” and “economic value creation” as two wheels of a car—creating social value leads to economic value, which in turn enables even greater social value creation.

In April 2024, upon establishing a new group management philosophy, the group identified six “Group Materiality” (key focus areas): “1. Contribution to Industrial Competitiveness,” “2. Coexistence with the Environment,” “3. Health and Vitality,” “4. Safety and Security,” “5. Diversity & Inclusion,” and “6. Compliance & Governance.” The group will address these material issues through its core business to contribute to sustainability.

[References]

・“Group Long-Term Management Policy” https://www.mitsuifudosan.co.jp/corporate/innovation2030/

・“Group Materiality” https://www.mitsuifudosan.co.jp/esg_csr/approach/materiality/