Thermal energy storage for buildings (phase-change materials, hot water tanks)

Buildings consume about 40% of global energy and produce roughly the same share of carbon emissions. Most of this energy gets wasted through poor insulation, inefficient heating and cooling systems, and outdated design practices.

The building sector moves slowly — most structures last decades, and retrofitting existing buildings is complex and expensive. Meanwhile, billions of people worldwide still rely on polluting fuels for basic needs like cooking and heating water, creating both climate and health problems.

Solving building energy waste requires both cutting-edge technology and practical approaches that work at massive scale. The opportunity is enormous: dramatically reducing emissions while making buildings more comfortable and affordable to operate.

Most buildings worldwide still burn gas, oil, or coal for heat, or use electricity from fossil fuel power plants for cooling. This creates direct emissions and locks in decades of future pollution.

Electrifying building heating and cooling is essential for decarbonization, but requires new technologies that work efficiently in different climates and building types.

Technologies that store heat or cooling for later use, allowing buildings to shift energy use to when renewable electricity is abundant. Phase-change materials absorb and release large amounts of heat as they melt and solidify. Advanced hot water tanks and other thermal storage can store energy for hours or days.