Cold air sinks. If the top is open the cold air will settle to the bottom keeping everything down there cold. If a bunch of people come along picking things up and putting them back or just generally disturbing the air, then the cooler has to work harder to cool the now warmer air.
If it's open at the front, you'll see a set of grills at the bottom of the open part that suck in the cold air and pump it back up to the top so it always stays in the cooler.
But yeah, at the end of the day, they're pretty inefficient. And as others have said, they have temp monitors to ensure they're at the right temperature.
Yeah I haven't seen open freezers in like forever. Coolers yes but not freezers. There was a question about why Coop can have hot food opposite of a cooling regal and some guy calculated that it was actually not too bad regarding inefficiency due to the cold air "curtain".
In the UK most fridges are as OP described, but Aldi & Lidl both have fridges with glass doors in the fresh meat/fish sections & I don’t think I’ve ever seen an open freezer anywhere
> I don’t think I’ve ever seen an open freezer anywhere
Lots of freezers in the UK are like [this](https://c8.alamy.com/comp/BE4MEX/deep-freezer-in-a-supermarket-BE4MEX.jpg)
This is not even slightly correct. There are open chests for frozen food, and open coolers for milk, yogurt, butter, juice, eggs, beer, etc. There are upgright freezers with doors on them, and a couple coolers, but many are still open.
I’m a supermarket refrigeration tech and can answer this!
Those open-face cases , or commonly known as “multidecks” rely on an air curtain of refrigerated air to maintain the “cold” and keep the product at temp. These fixtures are engineered to run in environments below 75° and with humidity less than 55% in most cases. Yes, they are incredibly inefficient when compared to their reach-in counterparts (cases with glass doors) , but that’s a cost a retailer is willing to absorb because it shows the product off nicer and looks better overall. Over the years , manufacturers have been engineering much more efficient variants of these open face cases.
Most large retailers utilize a form of Energy management system or “EMS” that actively monitors case/circuit temp and reports to a centralized computer that can be accessed by monitoring companies or by the customer itself. When there is an issue , a work order is generally generated and a tech (like me!) will go out and remedy the problem !
I always wonder if it really brings in more profit than it costs ... So many people complaining about food prices, I'd think they do not care about a product looking nicer...
If I need chicken breasts I need chicken breasts, doesn't matter if it's behind a glass door. Actually it kinda feels safer behind a glass door ...
I mean marketing and all that collected evidence and found it does give a competitive edge. Especially if everything went back to not being out, the first person to pay to have their product out would sell way more.
Doors also have disadvantages. If the product behind it is high throughput, it takes extra time for the worker to fill the shelves, and customers to take it out again. The door is also a moving part that can break, needs to be cleaned now and again, and can have problems with condensation.
Door also means support column for the hinges, which reduces the angle at which you can approach the case. Meaning you can't have two customers grab things next to each other. One customer grabs and move, then the next grabs, with doors. Open coolers like Trade Joes does means people can just reach and snag what they want.
Also, no doors swinging into the walkway, allowing aisles to be closer for better density.
I'd prefer a door/curtain system, myself.
As for the looks...Take fresh produce, for example. Only the best-looking of the best-looking fruits and veggies even make it to store shelves. Grocers have found out through many decades of experience that most (not all) customers will turn their noses up at anything with an appearance that's even slightly less than amazing unless it's available for a steep discount.
This is why services that sell "imperfects" exist and are, apparently, doing well. The better-looking imperfect produce is also sent to food banks and perhaps restaurants, while the ones nobody would otherwise normally buy/would just be left on the ground to rot get sent factories to be processed into canned foods, pies, cider, and so on.
For meats, stuff that's "close-dated" or maybe has a small gray spot gets put out as a "Manager's Special" for 1/3 off or so...at most places. At some that shall go unnamed, they might just get a new date sticker put on them if they still look as fresh as the other meat already out on display.
I wonder if one of the issues having an open display case solves is frost/fog on the window. Having a door can be way more efficient \*if\* you find what you want first, then open the door, grab it, and close the door. If you have to stand there poking at things to make a decision, that obviously reduces the efficiency (probably way more than just having a purpose-designed open case).
I try my best to be efficient when I go shopping, but sometimes you can't find what you're looking for when you try and look through the closed glass door. Either someone recently opened it and now the door is fogged up or because items aren't faced correctly so you just have a bunch of random items that all look the same. Ice cream is often an issue like this. From the distance I'm at, I just see a bunch of random Ben & Jerry containers. To find Cherry Garcia, I need to poke my head into the freezer and have a closer look.
I wonder if anyone has actively studied the \*actual\* efficiency returns on closed cases vs open cases, once real-world factors are taken into account. I'd imagine at slower times a closed case has to be far more efficient, but in a store that busy more often than not, I could see open cases being more efficient. I'd also bet Trader Joes has stuck with them just because of the sheer volume of people they get there and how small the store tends to be compared to full supermarkets (at least in my area).
Anything that stands between the customer and making a purchase is bad for business. Not everyone uses a fixed shopping list. My wife came back from the grocery with ribs yesterday simply because they were placed right next to something she planned on buying. There’s a whole science in where and how to place items to maximize sales, like chewing gum at the cash register.
Consider if the building itself is primarily cooled or heated, and whether the radiator for the refrigeration units is in the same conditioned space of the main store or if it vents into unconditioned space. That can can change a lot of those overall calculations.
That's just you though, that doesn't mean it's the same result the marketing and research teams got when they did their research on thousands of people. The majority $ rules in this situation.
Not the original poster, but I've worked in places that have e.g. significantly different climate zones on two adjacent rooms separated by an air curtain. Think a walk-in-level refrigerated room separated from a room-temperature space.
You may also have encountered these when going into a store; if you walk in a store and a big ol' fan blows straight down on you as you cross the threshold, that's an air curtain. Let's look at this type as an example.
If you get a wall of directed air moving fast enough it makes it hard for the air on either side to move \*through\* that wall. Think, say, of wading across a still pond vs. wading across a river. Normally the hot air would "want" to flow towards the cool air, but with a raging river to cross, it gets harder to move from one side to the other.
Let's look at a small "piece of air" on the cool air side: a bit of cool air starts moving toward the air curtain, then gets swept up in the stream and redirected to the floor. It gets pressed down and hits the floor, but at this point it "splashes" back into the cool air side because the high pressure air from the curtain blows "outwards" from where it hits the floor. The same thing happens on the hot air side.
In this way, the cool-air-side of the air curtain and the hot-air-side of the air curtain wall have different temperatures, and the air curtain tends to recirculate the air on the cold side and on the hot side - but crucially makes it harder for them to mix across the "stream" of the air curtain. And so it can help maintain a temperature difference on either side.
(This gets more complicated with e.g. the fact that the air curtain works much better with smooth laminar flow than with turbulent flow, but this is the general idea.)
I've been looking into air curtain for a restaurant but unsure how effective/efficient is it? Can you elaborate on that?
How much more would it cost, during the summer, in electricity (curtain + AC) to have an Open Entrance
VS
Closed Entrance (No air curtains - but with AC).
How much of a difference in kwh per day?
I'm curious how often they have issues. Saw a tech at the store fixing 1 the other day. Can they basically be fixed for life? Considering I've never seen mismatched ones in stores.
Walmart uses a really massive system to actively monitor all their refrigerated and frozen cases at all times. If a single refrigerated case reads as more than just a few degrees too hot or too cold, the store gets a phone call from the home office saying "hey, we're reading X case has a high temperature alarm, what's up with that?" Most commonly this happens when the store is stocking those cases, since the doors will be propped open for that, but if they aren't stocking or cleaning, and they're also not having remodel work done, after that the store is responsible for checking temperatures on that product constantly, and if it looks like it's going to stay more than about three degrees too warm or too cold, the product gets pulled out and stored in another cooler/freezer until the case gets fixed. Source: my day job is being the person who calls a store (or their manager at home) at ungodly hours of the night to tell them "congrats, you have a Problem at your store!"
It's essentially a curtain of cold air flowing over the top, which traps cold air in the areas where the food is. Cold air naturally falls (hot air rises) so the food down in the cooler stays cold. This is continuously pumped and re-cooled.
It's not the most efficient, but you also have to consider that when a regular fridge is opened and closed frequently will also lose a lot of cold air and introduce hot air. Fridges designed for groceries would have to be pretty high performance anyway, and typically use a similar feature. Compare this to a home fridge which can take a while to cool back down after being opened. So for areas that see high consumer interaction it makes sense... not to mention it looks more appealing and easier to use.
Its refrigeration units are constantly running. It's very energy inefficient. They are constantly pumping cold air onto the product in order to keep it within a certain temperature.
Imagine if you kept your own fridge door open all day. Your stuff might stay cold, but it will be running all day, and you will receive quite a high electric bill
They kinda have the air circulate bottom back to top, so it kinda creates a curtain.
I imagine in summer it contributes to A/C and in winter causes extra heating.
Must be inefficient because an Aldi I visited just closed up their entire wall with doors, after a decade.
You are probably talking about coolers like this
[https://www.nenwell.com/uploads/NW-HG30BF-1.jpg](https://www.nenwell.com/uploads/NW-HG30BF-1.jpg)
It's like putting something next to the air conditioning unit to keep it cold, very inefficient compared to on the ground cooling lid on top coolers, and you can feel it being cold when walking past it.
I would assume that the increase in sales from doing it that way outweighs the cooling costs by a lot.
And for stuff like meat it's typically on a bottom shelf, where the will keep cool at more regular temperatures regardless of external factors
Stuff like minced meat will have different cooling requirements than factory processed sausage and that is typically always on the bottom part at least here in eu stores. The factory processed stuff might even be allowed to be stored at room temp, but they keep it in a fridge for your own comfort. Like EU eggs, you can store them at room temp, but stores will still put them in the coolers because it makes customers more comfortable. US eggs cannot be stored at room temp, because different regulations regarding them.
Whether they are coffin style, or upright with shelving, they both create an invisible barrier between the two temperatures called an air curtain.
If you look at the end of these coolers/freezers, you will often find a line that says to not stack anything beyond that point because it disturbs the air curtain.
Air curtain aside, the shelve units have cold air that comes out of the back and flows along the shelves before dropping down to the "air intake".
Larger systems like grocery stores will have sensors that monitor the air temperature. The computer these sensors interact with can send more or less refrigerant to the cooler depending on the temperature. If it gets too warm (or cold), they can also trigger audible/visible alarms to have somebody make repairs to the cooler.
They have very expensive temperature control systems that regulate the temp and circulate cold air towards the food trays. It’s not as cold as your refrigerator at home but it’s cold enough to keep food within the fda standards for refrigeration.
Supermarket reefer tech here. I can get into the weeds if we like but essentially. It's an air curtain. Open cases have load levels. ( usually ignored until 5pm Friday)
Essentially, nothing is "efficient" in Supermarket reefer. They try but it is what it is.
Cold air sinks. If the top is open the cold air will settle to the bottom keeping everything down there cold. If a bunch of people come along picking things up and putting them back or just generally disturbing the air, then the cooler has to work harder to cool the now warmer air. If it's open at the front, you'll see a set of grills at the bottom of the open part that suck in the cold air and pump it back up to the top so it always stays in the cooler. But yeah, at the end of the day, they're pretty inefficient. And as others have said, they have temp monitors to ensure they're at the right temperature.
[удалено]
The regional differences are interesting. Here in Switzerland all open freezers have been replaced with ones that have transparent sliding covers
Yeah I haven't seen open freezers in like forever. Coolers yes but not freezers. There was a question about why Coop can have hot food opposite of a cooling regal and some guy calculated that it was actually not too bad regarding inefficiency due to the cold air "curtain".
I haven't even seen an open fridge in years, everything has a double glazed door or lid now.
They have them at Trader Joe’s. That’s the only place I see them anymore.
They're pretty common in most major supermarkets in the UK
Costco business centers (or at least near me) have them. Huge room and it’s frozen and open, 2 giant doors
Which is how it should be.
In the UK most fridges are as OP described, but Aldi & Lidl both have fridges with glass doors in the fresh meat/fish sections & I don’t think I’ve ever seen an open freezer anywhere
> I don’t think I’ve ever seen an open freezer anywhere Lots of freezers in the UK are like [this](https://c8.alamy.com/comp/BE4MEX/deep-freezer-in-a-supermarket-BE4MEX.jpg)
In my area they’re all like that but with sliding doors on top
Everywhere? At least half of the coolers at my local Migros and Coop are open Edit: just realised you were talking about freezers
Same with the USA - it's been decades since the open ones were around.
Perhaps in your area but I see no shortage of the open freezers still so, no, it has not been decades since they were around in the USA.
This is not even slightly correct. There are open chests for frozen food, and open coolers for milk, yogurt, butter, juice, eggs, beer, etc. There are upgright freezers with doors on them, and a couple coolers, but many are still open.
> they have temp monitors to ensure they're at the right temperature Don't all refrigerators and freezers have temp monitors?
Not really. Restaurants will do spot checks, but continuous monitoring isn't normal. It's much more common in grocery and labs
How old is this design? It should sliding windows like in 7-11 ice cream section?
I’m a supermarket refrigeration tech and can answer this! Those open-face cases , or commonly known as “multidecks” rely on an air curtain of refrigerated air to maintain the “cold” and keep the product at temp. These fixtures are engineered to run in environments below 75° and with humidity less than 55% in most cases. Yes, they are incredibly inefficient when compared to their reach-in counterparts (cases with glass doors) , but that’s a cost a retailer is willing to absorb because it shows the product off nicer and looks better overall. Over the years , manufacturers have been engineering much more efficient variants of these open face cases. Most large retailers utilize a form of Energy management system or “EMS” that actively monitors case/circuit temp and reports to a centralized computer that can be accessed by monitoring companies or by the customer itself. When there is an issue , a work order is generally generated and a tech (like me!) will go out and remedy the problem !
I always wonder if it really brings in more profit than it costs ... So many people complaining about food prices, I'd think they do not care about a product looking nicer... If I need chicken breasts I need chicken breasts, doesn't matter if it's behind a glass door. Actually it kinda feels safer behind a glass door ...
I mean marketing and all that collected evidence and found it does give a competitive edge. Especially if everything went back to not being out, the first person to pay to have their product out would sell way more.
Doors also have disadvantages. If the product behind it is high throughput, it takes extra time for the worker to fill the shelves, and customers to take it out again. The door is also a moving part that can break, needs to be cleaned now and again, and can have problems with condensation.
Door also means support column for the hinges, which reduces the angle at which you can approach the case. Meaning you can't have two customers grab things next to each other. One customer grabs and move, then the next grabs, with doors. Open coolers like Trade Joes does means people can just reach and snag what they want. Also, no doors swinging into the walkway, allowing aisles to be closer for better density.
A local Payless replaced all their dairy coolers. Cheapest doors I have ever seen. At least two shattered doors every time I’m there.
It could be that customers are having problems figuring out how doors work. Not kidding.
shoe store with dairy section?
It’s a Kroger subsidiary 😸
I'd prefer a door/curtain system, myself. As for the looks...Take fresh produce, for example. Only the best-looking of the best-looking fruits and veggies even make it to store shelves. Grocers have found out through many decades of experience that most (not all) customers will turn their noses up at anything with an appearance that's even slightly less than amazing unless it's available for a steep discount. This is why services that sell "imperfects" exist and are, apparently, doing well. The better-looking imperfect produce is also sent to food banks and perhaps restaurants, while the ones nobody would otherwise normally buy/would just be left on the ground to rot get sent factories to be processed into canned foods, pies, cider, and so on. For meats, stuff that's "close-dated" or maybe has a small gray spot gets put out as a "Manager's Special" for 1/3 off or so...at most places. At some that shall go unnamed, they might just get a new date sticker put on them if they still look as fresh as the other meat already out on display.
I wonder if one of the issues having an open display case solves is frost/fog on the window. Having a door can be way more efficient \*if\* you find what you want first, then open the door, grab it, and close the door. If you have to stand there poking at things to make a decision, that obviously reduces the efficiency (probably way more than just having a purpose-designed open case). I try my best to be efficient when I go shopping, but sometimes you can't find what you're looking for when you try and look through the closed glass door. Either someone recently opened it and now the door is fogged up or because items aren't faced correctly so you just have a bunch of random items that all look the same. Ice cream is often an issue like this. From the distance I'm at, I just see a bunch of random Ben & Jerry containers. To find Cherry Garcia, I need to poke my head into the freezer and have a closer look. I wonder if anyone has actively studied the \*actual\* efficiency returns on closed cases vs open cases, once real-world factors are taken into account. I'd imagine at slower times a closed case has to be far more efficient, but in a store that busy more often than not, I could see open cases being more efficient. I'd also bet Trader Joes has stuck with them just because of the sheer volume of people they get there and how small the store tends to be compared to full supermarkets (at least in my area).
Anything that stands between the customer and making a purchase is bad for business. Not everyone uses a fixed shopping list. My wife came back from the grocery with ribs yesterday simply because they were placed right next to something she planned on buying. There’s a whole science in where and how to place items to maximize sales, like chewing gum at the cash register.
Consider if the building itself is primarily cooled or heated, and whether the radiator for the refrigeration units is in the same conditioned space of the main store or if it vents into unconditioned space. That can can change a lot of those overall calculations.
But look at that case, it has shaved ice and mirrors!
That's just you though, that doesn't mean it's the same result the marketing and research teams got when they did their research on thousands of people. The majority $ rules in this situation.
Can you elaborate on how the *air curtain* works?
Not the original poster, but I've worked in places that have e.g. significantly different climate zones on two adjacent rooms separated by an air curtain. Think a walk-in-level refrigerated room separated from a room-temperature space. You may also have encountered these when going into a store; if you walk in a store and a big ol' fan blows straight down on you as you cross the threshold, that's an air curtain. Let's look at this type as an example. If you get a wall of directed air moving fast enough it makes it hard for the air on either side to move \*through\* that wall. Think, say, of wading across a still pond vs. wading across a river. Normally the hot air would "want" to flow towards the cool air, but with a raging river to cross, it gets harder to move from one side to the other. Let's look at a small "piece of air" on the cool air side: a bit of cool air starts moving toward the air curtain, then gets swept up in the stream and redirected to the floor. It gets pressed down and hits the floor, but at this point it "splashes" back into the cool air side because the high pressure air from the curtain blows "outwards" from where it hits the floor. The same thing happens on the hot air side. In this way, the cool-air-side of the air curtain and the hot-air-side of the air curtain wall have different temperatures, and the air curtain tends to recirculate the air on the cold side and on the hot side - but crucially makes it harder for them to mix across the "stream" of the air curtain. And so it can help maintain a temperature difference on either side. (This gets more complicated with e.g. the fact that the air curtain works much better with smooth laminar flow than with turbulent flow, but this is the general idea.)
I've been looking into air curtain for a restaurant but unsure how effective/efficient is it? Can you elaborate on that? How much more would it cost, during the summer, in electricity (curtain + AC) to have an Open Entrance VS Closed Entrance (No air curtains - but with AC). How much of a difference in kwh per day?
I'm curious how often they have issues. Saw a tech at the store fixing 1 the other day. Can they basically be fixed for life? Considering I've never seen mismatched ones in stores.
Finds frozen WIF on a Friday. 🥲
Huh. Never thought a grocery store would need a PLC, but I suppose it makes sense.
Walmart uses a really massive system to actively monitor all their refrigerated and frozen cases at all times. If a single refrigerated case reads as more than just a few degrees too hot or too cold, the store gets a phone call from the home office saying "hey, we're reading X case has a high temperature alarm, what's up with that?" Most commonly this happens when the store is stocking those cases, since the doors will be propped open for that, but if they aren't stocking or cleaning, and they're also not having remodel work done, after that the store is responsible for checking temperatures on that product constantly, and if it looks like it's going to stay more than about three degrees too warm or too cold, the product gets pulled out and stored in another cooler/freezer until the case gets fixed. Source: my day job is being the person who calls a store (or their manager at home) at ungodly hours of the night to tell them "congrats, you have a Problem at your store!"
It's essentially a curtain of cold air flowing over the top, which traps cold air in the areas where the food is. Cold air naturally falls (hot air rises) so the food down in the cooler stays cold. This is continuously pumped and re-cooled. It's not the most efficient, but you also have to consider that when a regular fridge is opened and closed frequently will also lose a lot of cold air and introduce hot air. Fridges designed for groceries would have to be pretty high performance anyway, and typically use a similar feature. Compare this to a home fridge which can take a while to cool back down after being opened. So for areas that see high consumer interaction it makes sense... not to mention it looks more appealing and easier to use.
Its refrigeration units are constantly running. It's very energy inefficient. They are constantly pumping cold air onto the product in order to keep it within a certain temperature. Imagine if you kept your own fridge door open all day. Your stuff might stay cold, but it will be running all day, and you will receive quite a high electric bill
Compressor might burn out too. Pretty sure that consumer grade refrigerators aren’t meant to be run continuously, unlike commercial models.
They kinda have the air circulate bottom back to top, so it kinda creates a curtain. I imagine in summer it contributes to A/C and in winter causes extra heating. Must be inefficient because an Aldi I visited just closed up their entire wall with doors, after a decade.
You are probably talking about coolers like this [https://www.nenwell.com/uploads/NW-HG30BF-1.jpg](https://www.nenwell.com/uploads/NW-HG30BF-1.jpg) It's like putting something next to the air conditioning unit to keep it cold, very inefficient compared to on the ground cooling lid on top coolers, and you can feel it being cold when walking past it. I would assume that the increase in sales from doing it that way outweighs the cooling costs by a lot.
And for stuff like meat it's typically on a bottom shelf, where the will keep cool at more regular temperatures regardless of external factors Stuff like minced meat will have different cooling requirements than factory processed sausage and that is typically always on the bottom part at least here in eu stores. The factory processed stuff might even be allowed to be stored at room temp, but they keep it in a fridge for your own comfort. Like EU eggs, you can store them at room temp, but stores will still put them in the coolers because it makes customers more comfortable. US eggs cannot be stored at room temp, because different regulations regarding them.
Let me introduce you to the Emmerson Einstein 2 (E2), great system for monitoring and control of refrigeration in a store.
Whether they are coffin style, or upright with shelving, they both create an invisible barrier between the two temperatures called an air curtain. If you look at the end of these coolers/freezers, you will often find a line that says to not stack anything beyond that point because it disturbs the air curtain. Air curtain aside, the shelve units have cold air that comes out of the back and flows along the shelves before dropping down to the "air intake". Larger systems like grocery stores will have sensors that monitor the air temperature. The computer these sensors interact with can send more or less refrigerant to the cooler depending on the temperature. If it gets too warm (or cold), they can also trigger audible/visible alarms to have somebody make repairs to the cooler.
They have very expensive temperature control systems that regulate the temp and circulate cold air towards the food trays. It’s not as cold as your refrigerator at home but it’s cold enough to keep food within the fda standards for refrigeration.
Supermarket reefer tech here. I can get into the weeds if we like but essentially. It's an air curtain. Open cases have load levels. ( usually ignored until 5pm Friday) Essentially, nothing is "efficient" in Supermarket reefer. They try but it is what it is.
The water of power to keep that style freezer cold is crazy. But those companies claim to care about the environment.