Renewable energy communities (REC) offer the possibility of joint production and supply of renewable energy sources. This article presents the framework conditions of REC in Austria and comprehensively analyses the financial and ecological effects of an REC using a newly developed analysis tool. The results show positive financial and ecological effects of the REC being investigated by introducing an external power supplier. A sensitivity analysis was applied to evaluate all parameters used in the simulation model and to identify the key influencing variables which are the grid electricity price, the inflation rate and the discount rate.