An ‘eco-cycle’ solution named the Hammarby Model, developed by Fortum, Stockholm Water Company and the Stockholm Waste Management Administration, is an integral energy, waste and water system for both housing and offices. The goal is to create a residential environment based on sustainable resource usage. Examples include waste heat from the treated wastewater being used for heating up the water in the district heating system, rainwater runoff is returned to the natural cycle through infiltration in green roofs and treatment pools, sludge from the local wastewater treatment is recycled as fertiliser for farming and forestry.