After ten years of global research, Dr Matyas Gutai’s water-filled glass heating and cooling system has proved successful in four out of five of the world’s climates. The system consists of a small pump and pipe-connecting water-filled glass windows with a storage tank. When exposed to sunlight, the water trapped between the panes of glass absorbs heat, keeping rooms cool in warm seasons. When the glass reaches a particular temperature, the pump replaces the hot water with cooler water. The tank stores heat, and in cold weather, the piping process happens in reverse, heating the building via the pipes and windows. By replacing traditional windows with the water-filled glass versions, no further aesthetic elements such as tinted glass or shutters are needed. Two prototype homes use the windows, with the first Water House located in Kecskemet, Hungary, and Water House 2.0 located on the grounds of Feng Chia University in Taichung, Taiwan.