Developers will have to install heat pumps and solar panels in all new homes in England under new building regulations. It follows the government's Warm Homes Plan, which promised £15bn to help UK households pay for green technologies as part of efforts to cut fossil fuel use and drive down energy bills. Heating homes accounts for about a fifth of the UK's planet-warming emissions, so switching from gas and oil to heat pumps is seen as a key way to help meet net zero targets. Heat pumps run on electricity instead of gas, and are more efficient than traditional boilers. They warm buildings by absorbing and amplifying heat from the air, ground, or water. Air source heat pumps - the most common type - suck in outdoor air and pass it over tubes containing refrigerant fluids. The heat from the outdoor air causes the refrigerants to evaporate into a gas. Compressing the gas increases the temperature, and this heat is passed round the home.…