In the smaller Tesco and Co-Op they have drinks and other stuff in big open-fronted fridges, but the drinks are always really cold.
How do they work? Are they just more powerful than a home fridge (which wouldn't do much if you left the door wide open) or is there some scientific sorcery at work?
No sorcery. They blow the cold air inwards, so that helps to keep the cold in. There's bound to be some mixing of hot and cold air, but the thermal capacity of air is quite low, and they just have powerful motors to compensate.
They drop a curtain of cold air from the top, and try to capture as much of it as possible at the bottom to be recycled, so it's not lost into the supermarket isles, although when you have an isle with open refrigerated units both sides, it normally needs warm air blown down from the ceiling to keep the walk space comfortable. They are much more powerful than a domestic fridge, but they are still built to be as efficient as possible given the design contraints of an open front (which your fridge isn't). Nowadays, they don't operate in isolation, and are part of the whole design for the supermarket aircon system.
When the store is closed, an insulated roller blind will be pulled down the front to make the units more efficient.
We've had a good summer, so I have to make a special effort to remember to take a jumper with me when visiting the supermarket. :)
The temperatures of the aisles in some shops are incredibly low. Indeed in one local shop the floor in front of the units feels close to freezing. Must take my IR thingy with me sometime soon.
I would really like to know what their electricity bills are like.
In some supermarkets they appear to be experimenting with leaving the slatted transparent curtains in place during opening hours.
The smaller Tescos have started putting sliding doors on their fridges, the ones that don't give you enough time to reach in and grab a can of drink before they shut & trap your arm.
And as they're due for replacement, most large supermarkets are replacing them with glass fronted cabinets.
The first time I saw this was in Amsterdam, and there was a notice next to the fridges telling all and sundry the impressive amount of reduction in CO2 production they caused each year. It was possible from the figures on the notice to work out the (quite short) payback period of installing them.
They didn't at the very recently expanded and fully refitted Morrisons here. Nor at the very recently opened Lidl (though their cool cabinets seem to spill less than those in other shops - and their low-level refrigerators and freezers both have effective lids). Nor, somewhat longer ago, when they refitted parts of Asda (definitely including cool cabinets) nor the ground-up new Sainsbury.
I am hoping that they do - as the coolth can be unpleasant. And at the end of the line we are paying for their profligate waste.
Maybe I'm going into the wrong supermarkets, then.
Or the right ones... :-)
In message , at 20:17:49 on Sun, 8 Sep 2013, alan remarked:
I noticed this during the recent heatwave. Sainsbury's also put up signs apologising.
I was in a tiny Co-op in a heatwave a few years ago (just down the road from where Roland used to live). It's roughly the size of a one-car garage, with
3 aisles, and about half of it is open fridges. The fridges were working hard, so they were pumping out lots of heat out the back.But the shop is unventilated, so the heat was coming out the back of the fridges, spilling into the room, and coming back into the front of the fridges again. It was one big viscious circle of heat-pump positive feedback, and the room got hotter and hotter.
Theo
On 08/09/2013 20:57, John Williamson wrote: ...
I've seen that for frozen foods, but not for chilled.
Colin Bignell
I suspect it reduces sales as, where I have seen it tried, the curtains have since gone. Certainly I find they make it more difficult to see what is on the shelves.
Colin Bignell
The open displays can only cool a certain amount below the room temp. If the room temp is not controlled, or cannot be kept below the max which still allows the refrigerated display to work, then they will need to close the display front. It will make them more efficient, but it will also significantly dent sales.
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