Caches often employ write-back instead of write through, since write-back avoids unnecessary transfers for multiple writes to the same block. For several reasons, however, it is undesirable that a significant number of cache lines will be marked \"Dirty\". Energy-efficient cache organizations, for example, often apply techniques that resize, reconfigure, or turn off (parts of) the cache. In such cache organizations, dirty lines have to be written back before the cache is reconfigured. The delay imposed by these write-backs or the required additional logic and buffers can significantly reduce the attained energy savings.