My idea is to replace the traditional sash windows in old British buildings with modern double-glazed ones, in order to reduce the heat loss and therefore save energy and reduce carbon emission. The manufacturers would need to produce new double-glazed windows adapted to the designs and sizes of the old single-glazed ones, in order to keep the same look of the building, without dramatically changing the national heritage. The government could replace the windows for the public for a reasonable discounted price, and use the old windows for recycling. This long-term solution does not require the public to change their lifestyle and does not restrict them in anything. People would live normally after the replacement, using less money and energy for heating.