UK households are being urged to try a simple freezer trick using bags of water to help cut energy use as winter approaches. A savings expert has suggested filling unused gaps in freezers with sealed bags of water, saying a fuller freezer leaves less space for warm air to enter when the door is opened.
How the trick works
Sam Whillance, savings expert at discount platform Deal Town, previously told The Mirror: "Most of the energy your freezer uses goes towards cooling down the air that comes in when you open the freezer door."
Whillance added: "So, when your freezer is full, there is less room for warmer air to come in, and the items that are in there will help to cool down any warmer air that does sneak in."
Filling the gaps
For households with plenty of unused freezer space, the suggestion is to use sealed bags filled with water to occupy some of the gaps. The bags should be strong and suitable for freezing, with enough room left for the water to expand as it turns to ice. Reusable ice blocks or bags of ice can also be used.
"If you do not have enough food inside the freezer to keep it full, using things such as ziplock bags filled with water, ice blocks or even just bags of ice can help prevent warmer air from entering," Whillance said. "These items are cheap and effective."
Other ways to save energy
However, households do not need to buy extra food simply to fill their freezer. Freezing leftovers before they spoil can be a useful way of making use of spare space while also cutting food waste. Containers and bags should be labelled and older food kept where it can easily be seen to avoid meals being forgotten at the back of the freezer.
A fuller freezer should also not mean one that is packed so tightly that it cannot operate properly. Food should be arranged securely, the door needs to close fully and any air vents inside the appliance should be kept clear. Households can also make better use of available space by flattening bulky food into suitable reusable freezer bags.
Another simple way to avoid unnecessary energy use is to keep the freezer door open for as little time as possible. Knowing where different foods are stored can reduce the amount of time spent searching, limiting the amount of warm kitchen air entering the freezer.
The advice comes as interest in household energy costs appears to be increasing. Analysis of UK Google search data by OKPromo found that searches for "energy bills" were up 64% compared with the same period last year, comparing August 28 to September 26, 2026, with the same dates in 2025. Cristian Constantin said: "The rise shows energy bills returning to attention as colder weather approaches."
The freezer tip should not be seen as a guarantee of a specific saving on energy bills, but rather as a small efficiency measure that can be used alongside other sensible habits. Keeping the freezer organised, avoiding unnecessary door opening, maintaining clear vents and making sure food is used before it spoils can all help households make better use of the appliance as winter approaches.
