Half of all the energy consumed by human beings is used in or by buildings – but for the most part invisibly. Worldchanging has profiled a neat monitoring system by David Vogt at Kondra Systems that sets out to answer the questions: ‘how much power does that microwave take to pop that bag of popcorn? What about your toaster or coffee maker? How much power does that ‘energy efficient’ refrigerator actually use? And does it really make a difference if you turn all those lights off all the time?’ Vogt’s project answers these questions elegantly – only to raise a new one: having made the invisible visible, how might the users of buildings respond meaningfully to the information it reveals? I recently abandoned a half-finished book about knowledge maps because of this dilemma. I discovered that thousands of affective representations of complex phenomena have been developed in recent times including many to do with buildings. Physicists have illustrated quarks. Biologists have mapped the genome. Doctors have found ways to represent immune systems in the body. Network designers have mapped communication flows in buildings. Managers have charted the locations of expertise in their organizations. Our world is filling up fast with representations of invisible or complex phenomena. But most of them are made and used by specialists as objects of research. The design challenge is not just how to design them, but also how to deploy these representations in such a way that they change behaviour. A brilliant book by Luis Fernández-Galiano called Fire and Memory: On Architecture and Energy puts this second challenge into historical context: visualizations of complex phenomena can attract attention—but the development of a shared vision of where we want to be is the harder part. (My book on knowledge maps morphed into a chapter on systems literacy in my new book. An extract is online).