The paper addresses the topic of energy savings in existing public buildings by designing an intelligent ICT-based service to monitor and control environmental conditions, energy loads and plants operation. A set of demonstrator buildings of the Politecnico di Torino and an interoperable web-based software and hardware solution for real-time monitoring and control are being implemented. So, lighting, heating, ventilation and air conditioning services, through both wired and wireless sensors networks will be connected and the running optimized. New control rules have been designed and tested in order to properly balance energy savings and comfort issues. The test cases have been modeled in DAYSIM (lighting simulations) and TRNSYS (thermal simulations). A combination of daylight harvesting and occupancy detection was proposed as lighting control strategies. For the thermal control presence detection and occupancy planning are used. In order to reach the best compromise, the time necessary to reach the set point temperature is estimated based on ambient conditions. First simulation results presented here show that it is possible to maintain user thermal and visual comfort while reducing the HVAC annual energy demand up to 13 % (for the presented cases) and the lighting electric consumption up to 50 %.