Rising energy costs and climate awareness have increased the popularity of hybrid heating systems in Finland during recent years. These systems – when operating according to design – can significantly cut both energy costs and emissions. However, this may often not be the case in reality. Lack of proper commissioning was identified as one of the potential causes for challenges in the operation of hybrid heating systems. Key personnel from eight field sites comprising e.g. schools, shopping malls and apartment houses were interviewed to find out potential deficiencies in the commissioning process. The results from these interviews were then compared to identify common themes, and based on these, suggestions to improve the situation in the future were made. Some of the key findings include that in Finland, a designated commissioning provider is often not appointed to the projects, and the commissioning process mainly concerns the testing and handover phases.