A new design of roof-integrated water solar collector is presented. It takes advantage of new synergies found between collector and roof. Its main concept is based on the use of water redistribution for changing the roof configuration. This design provides a low-cost system for household heating and cooling that could be even cheaper than conventional roofs with similar thermal qualities, by using fully its configurable property. In this sense, this design could help us to modify the deeply-rooted paradigm of the classic roof. (c) 2007 Elsevier Ltd. All rights reserved.