Cyclic defrost models often don't have a heater.
I have a 217 litre Oracle fridge, it is made in China by Haier. Somewhere between 10 and 20 years old.
It has a manual defrost freezer, but rarely needs defrosting - maybe once every year or two?
The fridge has no visible evaporator, it is hidden behind the rear wall of the fridge compartment.
When it is refrigerating, the back wall frosts up a little, when the thermostat switches it off, the evaporator slowly defrosts due to heat leakage in through the back wall and from the air in the fridge being above freezing temperature. There is no defrost element. Defrost water drips down into a collection gutter at the bottom, and is piped to a collection pan on top of the compressor, where the warmth evaporates the water into the kitchen air.
It also has no mullion heaters or any other heating elements, condensation around the doors is prevented because the refrigerant line (the warm side) does a loop around each door opening, just behind the surface, before going to the evaporators in each side of the cabinet, so the waste heat that has been removed from the interior is now used to prevent moisture condensing around the doors - in older models this was prevented with a low power heating element.
So my fridge is very energy efficient, when it is not actively cooling, it uses zero energy. Having said that, technology has marched ahead since my fridge was made, you can buy frost free models now that use less power than my cyclic fridge.
The power star ratings in Australia are measured/tested with an ambient temperature of 32 degrees C, to allow for high temperatures in the North of the country. That's about 90 degrees F. It's a pretty harsh test by world standards, from vague memory the standard test in Europe is done at 25 degrees C?
My fridge is rated to use 320 KW/h per year, which is close to 1 KW/h per day. In my home where kitchen temperatures are often around 20 degrees C, I have measured our fridge to use under 0.5 KW/h per day, so about half the official figure. I live in the cool South. The best models of similar size in new models are rated at about 200 KW/h per day.
