Energy Saving Potential of Rooftop Greenhouses: Case Study of a Multi-Story Residential Building in a Cold Climate

As urban areas grow and face climate-related challenges, rooftop greenhouses (RTGs) offer a promising approach for Controlled Environment Agriculture (CEA) to enhance urban food production while providing potential energy-saving benefits. However, the energy performance of RTGs integrated with mid-rise residential buildings, which represent a substantial proportion of the existing urban housing stock in cold climates, remains poorly understood. This study investigated the influence of RTG integration on the energy demand and indoor thermal conditions of a four-story residential building across cold-climate regions. Dynamic simulations using IDA-ICE were performed to analyze the influence of different glazing and shading configurations, comparing rooftop and ground-based greenhouse scenarios and host building performance. RTG integration reduced the host building’s annual heating demand by 6.2–7.6%, with thermal buffering primarily benefiting the top floor, where heating demand decreased by up to 24.2%, while lower floors remained largely unaffected. No summertime overheating risks were observed. Compared to a ground-based greenhouse, the RTG had a lower heating energy use by 2.8–14.6% depending on glazing and shading configuration, by using free heat from the host building. This study highlights the potential of RTG integration as a passive energy-saving measure, while supporting sustainable urban food production, contributing to more sustainable and climate-resilient cities.