New rules could affect nine in 10 rental properties in duchies of Cornwall and Lancaster and at Sandringham King Charles and Prince William could be forced to spend up to £10m upgrading hundreds of rental properties on their private estates to meet planned energy-efficiency rules. The government...
Source: [Guardian World](https://www.theguardian.com/uk-news/2026/aug/16/king-charles-and-prince-william-face-10m-energy-upgrade-bill-for-estates)