Introduction to the field tests the main objective of the ChangeBest project is to support the development of marketable and successful energy efficiency services. For this reason, a guideline was developed to fill the observed gaps in the markets. This guideline has been used by several companies (ESCOs and Energy companies) in overcoming problems and successfully developing new or optimized Energy Efficiency Services (EES), which are then field-tested. For example, an optimized EES (Energy efficiency service) consists of an existing EES developed in another country, targeting a new customer group or using new technology. A further important condition for field testing is that the identified EES is explicitly connected to declared energy savings. At the present time, there are 37 partners from practice implementing field tests. The descriptions of this field tests and ideas from the partner from practice have been summarised in tables format clustered as • Service models• Field of application and• Customer segment finally each partner from practice will improve the developed and tested EES into a professional business case calculation model. This 3rd issue of the ChangeBest newsletter gives an overview of all field tests.