Octopus Energy is advocating a "4pm rule" to UK households as temperatures plummet and energy costs remain high. The rule has previously grabbed headlines after being endorsed by Money Saving Expert (MSE) founder Martin Lewis, who maintains it can help retain heat and potentially reduce bills.

He initially discussed it on ITV's The Martin Lewis Money Show several years ago, but with the cost-of-living crisis still gripping UK homeowners tightly, it remains applicable. His team of specialists on the official MSE website also verified that, despite the segment being recorded in November 2022, "the tips still work".

The approach involves adhering to a particular rule at a designated time daily to maximise warmth in your property without requiring excessive reliance on expensive central heating. Backing up MSE, Octopus Energy states: "You'll keep more heat in your home with less energy if you pull your blinds or curtains before it gets dark, up to 17% reduction in heat loss."

It added: "Closing curtains in front of external doors can also help to block the cold out and trap the heat in."

Clarifying the procedure, the energy provider explained: "Whilst the sun is shining, keep curtains/blinds open to let in the free heat from the sun.

"When the sun sets, close curtains/blinds to keep the heat in and the cold out. Curtain liners (or even a shower curtain) can be added during the colder months to thicken existing curtains."

This time of year, the sun will set between approximately 3.30pm and 4.30pm, depending on where you are in the country. Experts recommend drawing your curtains around 4pm to keep the warmth inside your home, potentially delaying the need to switch on your heating.

This advice echoes a tip previously shared by Martin Lewis. He advised viewers to "Use tactical curtains."

By this, he meant energy-efficient curtains that help retain heat; these are typically thermal, lined curtains.

He further explained: "When the sun is shining, it is letting light and heat into the house, so you want the curtains open. When it gets dark, it's not, so you want to keep the heat in by closing the curtains. I know we all know that, but doing it rigorously can help insulate, especially if you line it with a fleece. There are lots of tips online on how to do that, and really cheaply-do it yourself."

Best curtains for keeping the heat inside.

The most effective curtains for retaining heat are those lined with thermal material and made from thick, heavy fabrics like velvet or wool. These materials are excellent at blocking out the cold from windows.

Opt for heavy fabrics with a high thread count, such as velvet, suede, or wool blends. These types of materials naturally excel at keeping heat in compared to lighter fabrics like silk or linen.

The effectiveness of thermal curtains lies in their lining. It's crucial to opt for curtains that boast a special thermal or blackout lining.

This lining typically comprises several layers of fabric, occasionally with foam or a rubbery back, which aids in trapping air and reducing the escape of heat.

For optimal results, ensure your curtains are a perfect fit for your window. They should extend a few inches beyond the edges of the window frame and reach all the way down to the floor.

This creates an effective seal and prevents cold air from entering the room. Installing a pelmet or valance at the top of the curtain rod can also contribute to retaining heat by preventing air from flowing over the top.