AbstractNowadays it is necessary to reduce the energy consumptions of the built environment. This problem has led, in the last years, to a series of regulations to promote high performance systems. These can create a new way of building that is aware of the energetic consumptions. Besides the systems to use the solar radiation to produce energy (as active solar systems i.e. solar thermal collectors and photovoltaic modules) there are the passive solar systems such as the greenhouse. The greenhouse systems have a great potential to improve quality of living and energy performance of the buildings. However, it is now important to adopt a valid evaluation method to assess the project efficiency. There are already spreadsheets (for example SERRA 5000, based on Method 5000 and SERRA 832, based on UNI EN 832/2001) which can evaluate energy performance and verify the effectiveness. The purpose of this research concerns the update of the existing spreadsheets for the winter (UNI EN ISO 13790/2008) and the definition of added spreadsheet for the summer period. In order to test this evaluation method, a case study has been evaluated and discuss.