Refarmed: using buildings’ residual heat and biowaste to support rooftop greenhouses

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Danish Refarmed uses the concept of "building-integrated agriculture" to create very short local production and supply circuits.

High-impact buildings (producing a lot of waste and excess heat) are equipped with rooftop greenhouses which turn all that waste into value - to support low-impact food production. Symbiosis is created between the building below and the plants grown on the roof, and the result is healthy, fresh, local produce, reduced energy use and waste and increased transparency and traceability.

Residual heat and biowaste from the building below, as well as solar power from panels and rainwater support the plants grown in the greenhouse. In this way, locally-grown food can be sold in the supermarket two floors below. Excess heat from the supermarket below (Bilka, in this case) will heat the greenhouse throughout the year and rainwater will be used to irrigate the plants and provide what is needed for aquaponic production of fish and plants. Biowaste from a restaurant downstairs will also be used for compost, with both economic and environmental benefits.

Main results
  • Thanks to the symbiosis between plant growing and the building, expenses are around one third less than conventional farming, primarily due to the use of residual heat.
  • Greenhouse gas emissions are also reduced: for example, Refarmed lettuce will produce around 0.04 kg CO2e less. With a production of 160 000 units, that adds up to an annual reduction of 6 400 kg of CO2e.
  • By using residual heat (instead of using energy to create it), rainwater (instead of fresh water) and biowaste (i.e. less fertiliser), rooftop farming will emit 46 tonnes/year of CO2 less than traditional farming.