It seems that there is not a clear consensus among industry professionals on how green certificates should be valued, even though, there seems to be a consensus that certified properties are potentially valued higher than non-certified properties. This study aims to find out whether the potential extra value of a green certificate could be measured with real option valuation (ROV). Data was gathered from industry professionals using a standard discounted cash flow valuation method constructed in a spreadsheet. ROV was applied in the data using Collan's pay-off method. The results show that an average real option value of 985,000 Euro (or 8.8% premium to the average property value) was found for the green certificate. The main finding is that by examining the certificate as a real option, the potential extra value of a green certificate could be added into min and max case scenarios, thus, making it not necessary to alter the normal cash-flow scenario that should be based on the comparable data available from the market which is scarcely available for certified buildings.