Comprehensive research has dealt with the question whether property markets show price premiums for buildings that feature ‘green’ characteristics such as low energy consumption or a building certification. We expand existing research by raising and answering the question if housing properties that were explicitly advertised to feature ? ‘green’ ceating technology based on renewable energies or ‘brown’ heating technology based on fossil energies or even obsolescent technology come with significant price differences in association with these technological differences. For this purpose, we perform large-sample geoadditive regression analyses on the basis of a private dataset, which originally contains more than 3 million raw observations from German residential properties of 2015. We indeed find significant impact on housing prices, which is specifically visible in the form of a ‘brown’ discount for properties that are powered by fossil-fueled energy systems. From our findings, we suggest that low-energy consumption levels may still lead to price discounts c.p. if it is caused by mainly building-related quality and system-related measures stay unperformed.