10167880H-WIN: Hackney Window Innovation for Net ZeroClosedProcurementInnovate UK_H-WIN: Hackney Window Innovation for Net Zero_ is a demonstration project led by Water-Filled Glass Ltd in partnership with the London Borough of Hackney. It will trial an innovative, energy-saving window retrofit technology in a real-world setting to support the UK's transition to Net Zero. Traditional glazing is a major cause of energy loss and overheating in buildings, responsible for up to 40% of heating and cooling energy demand. Water-Filled Glass (WFG) is a patented system that replaces the insulating gas in double glazing with circulating treated water. The water absorbs and stores heat during the day and releases it at night or in colder weather, creating a more stable indoor environment and reducing reliance on heating and cooling systems. WFG can cut energy loss through windows by up to 72% compared to standard double glazing. The _H-WIN_ project will install WFG units in a Hackney-owned building, alongside sensors and a control system to monitor energy and comfort performance. The goal is to gather practical insights into how the system performs in everyday use, how it's installed, and what benefits it delivers for carbon savings and building users. This evidence will support Hackney's decision-making on wider adoption and help WFG Ltd prepare for commercial rollout. WFG offers a practical retrofit solution for public buildings, allowing major improvements in performance without replacing the entire window. It reduces disruption, preserves daylight, and lowers costs -- key benefits in live settings like schools and offices. By working closely with the London Borough of Hackney, this project will help bring an innovative UK technology closer to market, support affordable decarbonisation, and contribute to the Net Zero transformation of the UK's building stock.