Cooling a large restaurant / bar, evaporative / AC?

Heating and Cooling
1

Hi all

Friends of mine built a restaurant and bar which is around 280 SQM, basically a large high roof structure with some brick but also lots of glass on the sides.

The pitched corrugated roof is insulated, but apart from that they haven’t really considered actively cooling the space, to be honest I think they totally underestimated the additional heat generated by a bunch of people inside a venue.

Out of despiration they went to buy a couple of massive industrial fans between Christmas and new year, those you often see in large stores like Builders. They get air moving and make the space somewhat more comfortable, but the problem with them is they are loud as fudge and in my opinion totally spoil the vibe of the place.

One of the partners got a idea to add mist sprayers to the fans to make them more effective, but it won’t solve the noise problem. To give you a idea, yesterday morning I was there before opening time again, I played around on the newly installed sound system and got a lekker balance going in the different zones, background music in the restaurant and outside on the stoep, rugby replay in the background in the bar, but as soon as someone switched on the fans, it drowned out everything from the sound system, you might as well have just turned it off.

I don’t think aircons is really a option, the space is simply too big and the large stacking doors on both sides remain open all day. I have experience with massive portible aircons used in marquee tents for events and can imagine the result will be much the same, a huge amount of noise and no difference in temperature unless you stand right in front of it.

I read up a bit on evaporative coolers and it seams worth a try. Apparently they are just as loud as wall split aircons, so that will already be a win and they are apparently ideal for the climate in Gauteng.

Power consumption is also much less than aircons, they have solar and will have the capacity for a extra 3 or 4 kW draw.

The water use is also not a problem, the property have a strong borehole with a solar pump, so water is free.

does anyone have experience with evaporative coolers in large spaces, alternatively any other ideas?

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Where’s the place? Gauteng? Near the coast?

Evap coolers work in dry atmospheres. They work by the fact that when water evaporates it cools the air a bit. That’s why mist sprayers also work - tiny droplets evaporates where they are sprayed and thus cools the air.

They don’t work in high humidity places - e.g. not near the coast. That’s because the air is already much too saturated with water and thus more can’t evaporate easily.

My in-laws (who stay in Pretoria) have an evap-cooler for their house with outlets in 5 - 6 rooms and it is generally pretty amazing - not ever bone-chilling cold like an aircon and yet never super hot either. The unit also runs pretty low on energy - basically just a big fan and a pump to get the water into the panes where it can evaporate. Theirs is on the roof.

Once you know what to look for, they are actually surprisingly common around here in Gauteng - I see plenty of these on roofs:

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Inside the only sound we hear is the bit of air blowing through the vents in the ceiling. It is much more quiet than my 24k BTU split aircon - because there’s no fan inside blowing air around (my AC unit is about 5m away through effectively 2 walls, so that’s not the part we hear).

If I recall correctly, with an evap-cooler you have to have doors open because you’re effectively humidifying the air and thus you want to the high humidity air to “get out”. So it may be even better for a restaurant. But don’t quote me on this.

Of course, they do require water, and because they’re evaporating water, you’re going to likely find that whatever’s in the borehole water will cake onto the panes very quickly. So be prepared to swop those out reguarly. My borehole has seriously hard water, and I can imagine the calcium-carbonate caking up an evap cooler quickly.

There’s also a reason why they’re often called “swamp-coolers” – because if you don’t clean out those panes, they will start smelling like a swamp eventually as bacteria grow in them.

3 Likes
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Can filtering not reduce this effect?

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The place is in Gautengeleng. I also already read about the water quality, as with everything in our valley, due to the hard borhole water, gas geysers, heat pumps etc. all get filters to soften the water and also gets serviced more frequently than generally recommended.

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Another way, but we’re talking lots of money, is air curtains at the door (door can remain open, but the cold air is kept inside by a wall of air).

My inlaws in the Karoo has a “swamp cooler”, and it generally works alright, but it does raise the humidity in the room a lot.

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I think a lot of heat radiate through the roof and large windows which are not open, so I don’t think air curtains alone will make much of a difference here.

Chat GPT tells me if you install massive aircons and then also air curtains at the doors it will work.

But it says if installing big Evaporative coolers, you should not install air curtains because there must be constant airflow from outside.

It says you can install air curtains on smaller doors like the staff doors to the kitchen etc. but to leave the large stacking doors open when going the evaporative cooler route.

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This is effectively what supermarkets do, so the doors can be left open, but the inside can be air-conditioned. You still need a massive aircon to cool the inside. The air curtains however reduce your losses out of the doors. Comes at a cost though.

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Methinks the owners need to consult specialist in keeping large spaces cool.

Pretty sure it will cost a bit of money but if it is done right for the next decade or more at no extra costs, that would be a win.

2 Likes
9

An interesting side note here is one of the supermarket chains in the UK wondering how well directed all this cold air was, and how much it was costing them to cool that air.

They called in a formula 1 team (Williams) who did analysis of the airflows and found that a lot of air from deep freezes was spilling out and heading for the ground.

They designed little ̶c̶a̶n̶e̶s̶ vanes that could be fitted onto the lips and shelves of the deep freezes and redirect flow so that the cooled air was kept inside the deep freezes.

Result: reduced energy bill for the chain, and so reduced foot print.

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They use this method even in Clanwilliam’s “new” Spar and works great, and Clanwilliam gets pretty hot. But yes, you then still need the big aircons to actually cool it down.

Maybe a combination of evaporative cooler and aircon can work - Aircons really dry out the air and after a while it isn’t great. I got bad itching all over my skin this summer due to being in aircon rooms all day.