Sticking to the ‘rule’ every day can make your house feel warmer at night
Charlotte Smith Senior Lifestyle Content Editor
11:42, 20 Nov 2025Updated 11:51, 20 Nov 2025
Octopus Energy has shared the same advice as Martin Lewis once did(Image: Getty )
Octopus Energy is urging UK households to follow a ‘4pm rule’ as temperatures drop and energy costs remain high. The strategy has previously gained attention after being endorsed by Money Saving Expert (MSE) founder Martin Lewis, who suggests it can help retain warmth and potentially reduce bills.
He initially discussed it on ITV’s The Martin Lewis Money Show a few years ago, but with the cost of living crisis continuing to squeeze UK homeowners’ wallets, it remains applicable today. 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 optimise warmth in your property without depending too heavily on expensive central heating, reports the Mirror. Setting out the ‘rule’ on its website, Octopus Energy says: “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.” Detailing what to do, 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.”
Today, November 15, the sun will set between approximately 3.45pm and 4.25pm, depending on your location. Experts suggest closing your curtains around 4pm to retain the warmth inside your home, which may help you delay turning on your heating.
The guidance mirrors advice previously shared by Martin Lewis. At the time, he told viewers: “Use tactical curtains.” He was referring to energy-efficient curtains that help keep the heat in; these are usually thermal, lined curtains.
He added: “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.”
Keeping windows covered when it gets dark can help trap heat inTop curtains for retaining warmth indoors
The most effective curtains for keeping heat inside are thermal-lined ones crafted from thick, heavy materials like velvet or wool. These fabrics work brilliantly to block the cold from windows.
Opt for heavy fabrics with a high thread count, such as velvet, suede, or wool blends. These materials are naturally superior at retaining heat compared to lighter fabrics like silk or linen.
The effectiveness of thermal curtains lies in their lining. It’s important to opt for curtains that feature a special thermal or blackout lining. This lining typically comprises several layers of fabric, sometimes with foam or a rubbery back, which aids in trapping air and reducing heat loss.
For optimal results, ensure your curtains are a good fit for your window. They should extend a few inches beyond the window frame and reach all the way down to the floor.
This creates an effective seal, preventing cold air from entering the room. Installing a pelmet or valance at the top of the curtain rod can also contribute to heat retention by preventing air from flowing over the top.