One main objective of demand response is to release grid pressures imposed by building peak demands through changing end-user electric usage in response to electricity price changes. Conventional demand response in heating, ventilation and air-conditioning (HVAC) systems is performed in an uncoordinated way which merely focuses on individual-building-level economic benefits. However, its building-group level performance, which is the real concern to grid, has not been systematically evaluated. Thus, using operation data of real buildings, this study evaluates performance of conventional demand response at building-group-level under common electricity pricings. The evaluation results disclose major limitations of conventional demand response due to lack of coordination. Under time of use pricing, conventional HVAC demand response cannot effectively and efficiently reduce peak demand at building-group-level. Under dynamic pricing, conventional HVAC demand response can cause a new undesirable peak demand at building-group-level which could be much larger than the original one and impose stress on grid. Coordinating demand response of individual buildings can solve these limitations. With improved performance at building-group-level, simple coordinated examples have been given to demonstrate the need of coordination in conventional demand response. The study results show the significance of coordination in demand response and the grid pressures imposed by building peak demands can be better released if coordinated demand response implemented. (C) 2016 Elsevier B.V. All rights reserved.