My existing fridge and freezer are over 20 years old and there are better insulated quieter models available that use less than half as much electricity.
Being under the worktop without any rear ventilation uses 25-30% more electricity too because the heat has nowhere to go. The fridge also becomes a freezer in the summer because the trapped heat at the back affects the internal thermostat resulting a feedback loop until my carrots are sitting in a frozen pool of ice.
Not enough space
Before I can get a new fridge and freezer they need to fit under the worktop. There are two popular widths for these appliances (55cm and 60cm) and both of the existing ones are 55cm wide in a space designed for that size only. In order to get the models that I want to fit I need to find an extra 5cm of space because the new fridge is only available in 60cm wide.
The cabinets to either side are made of wood so I took one of them out and made it 5cm narrower:
The cabinet doors are now too wide for the cabinet so one of them needs to be made smaller:
There's now an extra 5cm of space so I can fit a 60cm and 55cm appliance under the worktop.
Not enough ventilation
The instructions for the new fridge and freezer come with warnings of damaging the compressor if there's no ventilation at the back. Some of the heat can escape over the top (to the front of the worktop) but not enough to stop an excessive build-up of heat in the summer.
I cut a long narrow ventilation hole in the back of the worktop and laser cut a cover for it out of plastic:
There's now enough ventilation for the heat to escape at the back. Be careful doing this with old appliances because my freezer immediately developed a condensation problem now that the excess heat was no longer warming the outer surfaces.