Not even older, it's a standard heating technique in the UK and Ireland, even in modern homes built last year. You can use an air-to-water heat pump to retrofit

Not even older, it's a standard heating technique in the UK and Ireland, even in modern homes built last year. You can use an air-to-water heat pump to retrofit a condensing gas boiler. Some even come integrated in to the hot water storage tank - https://rointe.ie/electric-water-heaters/heat-pumps/ https://rointe.ie/electric-water-heaters/heat-pumps/ Theoretically you could indeed drive cool water to the radiators to cool the house, but you don't get the convection effect that a radiator produces when hot, nor thermal radiation. So you need to rely on transfer of heat from the air to the metal of the radiator, potentially with no airflow. Easier to open the windows. In the last 12 years, I've never wished I had a system to chill the air in my dwelling; Ireland is generally on the cool side (though this may change).