Yes, you should make the most of any natural heat and energy that enters your home. So on warmer sunny days, you can leave the curtains open to let in light during the day and close them when the sun goes down.
By doing this, the curtains will act as an extra insulation layer and help to retain warmth – the same is true even in winter when you might be trying to leave the central heating off for as long as possible to combat rising energy costs.
For more handy hints and tips to keep your energy bills home while keeping cosy and warm, visit our dedicated blog, 23 ways to keep warm without turning the central heating on.