Dr. Matyas Gutai of Loughborough University has developed and tested a new energy efficient building option, Water Filled Glass (WFG) windows. The WFG system holds water between layers of glass windows, allowing the sun to heat the water, providing insulation and sound proofing. The hot water is then pumped out, replaced, and stored in a water tank. When the temperature drops, the hot water is circulated around pipes to heat the building.