On sunny days the air in loft spaces tends to heat up even if the air outside is cold. I was thinking that all that heat goes to waste as it's insulated from the house by loft insulation.
While making some thermostatically controlled fans for an electronics project, the idea came to me of putting something similar into the loft to pump the warm air into the house on cold days.
Anyone have any ideas on this? Seems technically fairly simple, but maybe I've overlooked some reason why it wouldn't be a good idea...