Shop cabinet and cool room sustainably « Alternative Technology Assn Forums

Alternative Technology Assn Forums » General

Shop cabinet and cool room sustainably

(30 posts) (11 voices)

Started 1 year ago by LaSource
Latest reply from LaSource

Tags:

cooling

LaSource
Member

Folks,

There is a great group of people starting a food co-op shop who want to know what they can do to make a double glass fridge in the shop and a cool room in the shed out the back greener.

It will be a leased property but the landlord is very open to working with them. Some funds may be available.

Anyone have any good ideas on how to reduce the impact ?

To stimulate the conversation here are a few brainstorms;
* Determine how to pre-cool the air
* Find new ways to exhaust the hot air generated and increase efficiency
* Develop best practices to keep the operation efficient (Eg; opening closing the cool room)
* Add thermal mass eg; Put tanks of water in the cool room to buffer fluctuations
* Additional insulation
* Add an air lock extra door
* Provide a window than can be used to pass food through rather than leaving the door open to let all the cool air out
* Turn off the cooling when allot of access will be occurring
* Create a waste height solid fence to catch cool air and slow its departure on opening.
* Ensure compressor is an efficient one

Do any of these make sense - have you a better idea ?

Tony

Posted Thursday 14 Oct 2010 @ 8:15:46 am from IP #
CunningPlansDept
Member

When you say pre-cool the air, are you cycling the air or using make-up fresh air or somesuch?

I think you've got it reasonably covered but I'd boil it down into a few key principles to use when looking at the set-up:
1) Keep external heat out (radiant, convective, conducted)
2) Maximise temperature differential at heat exchanger hot side
3) Minimise air exchange
4) Minimise what is being cooled and removed/replaced in the room (crates etc)

A suggestion for 2 is maybe an earth tube or drawing air from under the building or similar and running it past the heat exchanger.
And for 3 is to compartmentalise as much as possible, particularly in the fridge if it's vertical and you cant use a chest fridge.

Posted Thursday 14 Oct 2010 @ 10:03:13 am from IP #
PV2010
Member

LaSource

I have been looking at a product that optimises the compressor run cycle, I have had a meeting with the suppliers and the product looks reasonable. I have not checked up on the references they gave me but intend too before I determine if they are suitable for some projects I have in mind. It is commercially available if you want to follow it up. The unit I was looking at was for a cool room and was costed around $2500

http://www.smartcool.net/documents/media/Smartcool%20Magazine.pdf

CPD
On earth tubes ,I came to the conclusion that the risks and costs out weighed the benefits in humid regions especially when dealing with public/food.
Also with the underfloor air resource, recent experience has underlined that it is essential that any air intake is hermatically sealed from the air in the underfloor space. There is a high risk (apparently) of lots of nasties including Radon and whatever else was maybe "living" under there. I ended piping in air from the south side of the building to a floor vent (mechanical) and then extracting via a ceiling exhaust. The system is on a timer so it can night purge or be switched manually. I have a diagram but not sure how to post it on here,(just for interests sake).

Apparently LEDs love being fitted in cooler climates (<85C ), so any internal display lamps could be retrofitted. You can also get cheap T5's if you have a limited budget, I have used these before and they're super easy to install

Posted Thursday 14 Oct 2010 @ 11:46:59 am from IP #
Johnnojack
Member

Ideas? here's an old one. Heavy clear plastic strip curtain just inside coolroom door.

Posted Thursday 14 Oct 2010 @ 12:43:35 pm from IP #
dave lawrence
Member

any chance of creating an airlock between the coolroom door and the outside.?

Posted Thursday 14 Oct 2010 @ 7:52:30 pm from IP #
ghostgum
Member

I read about a supermarket that replaced the glass door fridge lighting with LED, on a motion sensor. If there was no one in the aisle, then the lights would turn off. As PV2010said , LEDs like running in cold conditions, unlike fluorescents. You can turn an LED on and off easily, with no warm up time.

Posted Thursday 14 Oct 2010 @ 10:31:25 pm from IP #
Buzzman
Member

Presumably as they are renting premises, the fridge and cool room are existing?

Retrofitting is always a pain in such circumsatances as cool rooms are usually 'built for space' rather than free-stanging like fridges.

The plastic strip curtain is a good idea, as is self-closing door (many are rollway or sliding, so tend to get left open.

Also, use of large plastic tubs rather than simply stacking stuff on open shelves or in open-sided crates. This means that when door is opened, cooled air INSIDE tubs does not fall to floor and seep out door, meaning less volume of air has to be cooled when door is closed, meaning motor cycles less often and for less time each cycle.

I'm talking 60L tubs - like double the size of a milkcrate but with solid sides. And they should have lids so no drips can contaminate.

Ideally have a custom-designed cool store pupose built so it is like a series of horizontal and seaprate fridge compartments, each with it's own thermostat. No glass doors, just good labelling on solid (insulated) multiple doors.

Then each visit to the cool store is like opening a small bar fridge, with a correspondingly small loss of cooled air.

Cool rooms are often located at rear of premises in less-well insulated area, or against the back wall which maybe receives direct heat from sun.....

So properly locating and insulating should be first principle.

Remember the old milkbar fridges? They had lids on top, so worked like a chest freezer when opened (ie: minimal loss of cooled air).

I have seen in some enlightened coffee shops, a 'well' in the bench next to the coffee machine which is chilled from underneath, so that milk in bottles stays cold but is easily and readily accessible without opening the actual fridge.

Eventually, display fridges will have separate compartments and separate doors, so if a higher door gets opened, less cooled air is lost, thus reducing cycling times.

But I do like the idea of LED display lighting on motion sensors. Cool!!

Posted Friday 15 Oct 2010 @ 4:47:52 am from IP #
LaSource
Member

Thanks all for the great ideas and advice. I will see what we end up doing and re-post.

Posted Tuesday 19 Oct 2010 @ 7:28:50 am from IP #
PV2010
Member

Yes great ideas, I'll try some of the soft approaches first instead of the high tec options ( and high cost $$$). It will be great to see how you go LaSource. I'll keep this thread updated with any successes (or failures) from my end

Posted Tuesday 19 Oct 2010 @ 10:03:33 am from IP #
Buzzman
Member

PV2010
The product of Smartcool's you looked at that was $2500..........was it the EMS or the ECO-3??

I have a minimart client with two large walk in coolrooms, older style, with single compressors.

Can you provide more info on your discussions??

Posted Thursday 21 Oct 2010 @ 7:32:42 am from IP #
dymonite69
Member

The ideal cool room looks like an energy efficient house with an air conditioner. Radiant barriers, lots of insulation, well sealed, entry air lock and thermal mass inside to buffer temperature changes. If you had slope down to the floor than less cold air will convect downward. Keep the compressor in a shaded and well-ventilated area.

Posted Thursday 21 Oct 2010 @ 9:26:37 am from IP #
PV2010
Member

Buzzman

I was told ( by the techie/dealer)the ECO3 was suitable for walk in chillers, the guy told me it was around $2500 (I usually work ex GST, so assume these costs also) this cost may include install and calibration I didn't check. The other unit the EMS came in at over $12000 installed ( i switched off at this point as it was more than I had to spend for the project). These larger units are for large building AC systems,which I wasn't interested in at the time. Anyway I have tried ringing North Sydney Council who have one but could not get through.
Basically the unit works by cutting the run cycle of the compressor and keeping it to a closer temperature band, the stopping of the compressor allows the compressor to keep cooler whilst reducing the power demand in that period it is off. He drew a good sketch demonstrating how a normal compressor runs through a cycle.
He said something like this .......
"......(for the temperature range to be delivered by the compressor and its cooling capacity)imagine a sinusoidal wave, as it comes from + down to the zero line (our optimum temperature) the compressor is shutoff, usually the cycle would take the temp through the - of the wave and pass the 0 point again.
Or describing it another way.... it would be like lopping off the - side of our sinusoidal wave.This is where the 'tweak' and efficiency savings come from"
The device is meant to be approved by a number of manufacturers and used by the some of big AC companies.
I haven't done enough homework on it to recommend it, give me a couple of weeks and I'll tell you if the walk-in chiller project is going ahead

Posted Thursday 21 Oct 2010 @ 10:20:08 am from IP #
dymonite69
Member

Does it work like an inverter AC.

Posted Thursday 21 Oct 2010 @ 11:00:09 am from IP #
Jeffbloggs
Member

Hmmm
Sounds like all they are doing is turning off the compressor prematurely (ie shorter more frequent cycles, smaller delta temp cycles) to allow the condenser to cool down before the next shortened cycle, which effectively increases condenser performance. I dunno if this works that well on a appropriately sized condenser module, or if the more frequent stop/starting of the compressor does it any good, even though there is possibly less overall running time. (Maybe be wary of the warranty conditions of your refridgeration appliances as well?)

Dyno69
Doesn't look like it from what I can tell. There doesn't seem to be any "analog" speed control of the compressor, only really a simulated "digital" speed control via increasing the on/off switching frequency at under 1Hz. Not really the same thing as an inverter AC unless you take the switching up to 50kHz or more and make it a switchmode power supply. Dunno if a standard compressor would be happy with that though.
BTW fully agree with your ideal cool room post. The better you can seal and insulate the cool room the less cooling and energy (ie smaller compressor) is required, spend more on the box than on the compressor is all I can say.

Posted Thursday 21 Oct 2010 @ 11:38:13 am from IP #
PV2010
Member

...mmmmmm, I hadn't thought about it to that degree but I reckon.....
the AC inverter works by changing the voltage/frequencey to control the electical load (compressor in this case). From the understanding I have the Smartcool products use switching rather than voltage regulation. Looking at the pictures of the product they look more like PLCs then VSDs ( I just read specs again of the Smartcool, it is not the same as an inveter/VSD control system)

Also the EMS is designed for large chiller based aircon systems, I don't have my notes but I believe it was a VAV type system rather than the smaller pack type. That also suggests it can be used with a VSD.
Great questions because I'll ask the manufacturer next time I speak to him!!!

Posted Thursday 21 Oct 2010 @ 11:47:44 am from IP #
Jeffbloggs
Member

A VSD (variable speed drive) is nothing more than a switchmode power supply in which the output waveform, voltage, current and frequency can be varied. This then drives an AC motor at a constant/variable preset speed. The AC-DC-AC conversion is only necessary so that the output waveform can be resampled by evening out the input waveform to DC. (ie battery charger to inverter in same device) That is why, from as far as I can tell from the links, that it only switches on or off ie "digital" IO. There is no compressor speed control. BTW PLC's can also have PWM, analog as well as digital In/Outs, and is commonly used to control a VSD via an analog 0-20mA signal.

Another point to maybe consider with an inverter or VSD controlled AC compressor is if the device is thermodynamically optimized to operate at variing speeds.

Posted Thursday 21 Oct 2010 @ 12:35:27 pm from IP #
PV2010
Member

Jeffbloggs

Your analysis confirms the functionality of the device in question. "It" only has the function for switching on and off, this is why (apparently)it is compatible with a number of different brands. The control of the switching then relies on the commissioning of the system, the suppliers were quite adamant of the skill set required for succesful commissioning.

Posted Thursday 21 Oct 2010 @ 12:48:13 pm from IP #
dymonite69
Member

" spend more on the box than on the compressor is all I can say."

Agree.

Posted Thursday 21 Oct 2010 @ 1:15:09 pm from IP #
marcusmucus
Member

Hello everyone,
Firstly its so great to find a forum like this and a big thanks in advance for any advice. We are in a very similar position to those that first started this thread. We are also a small organic veg co -op that has turned into a business. We are also living in a rental property and looking to install a cool room.

We are looking into something around 2.4x.2.4 x 2.4 or 3.6 x 2.4 x 2.4 and it will be positioned outside in a realativly shaded and protected spot. (flush against a east facing double story brick wall and under a huge locate tree).

So i have started looking around for some 2nd hand panels or complete units but have found it rather hard to source information of the best panels to buy as well as the most efficient cooling systems. Seems to me to be a pretty low priority in the industry.

so, my questions,

-Are there big differences in the r value of various brands of insulation paneling? .. and other environmental issues between types/companies in how they are manufactured? any advice?

-same goes for the cooling systems. do some companies make better/more efficent compressors/motors than others?..(we will be wanting a single phase drop in )

we are fairly limited with our budget and will really need to source the paneling 2nd hand, and possibly install ourselves. We will need a floor in the coolroom, would it be smart to put in a thicker floor , say 100mm- 150 mm?, any rough idea of a good price per m2 for panels?

Does anyone have a company they would recommend in Melbourne to help us, We have been approached by a few people, but my guts tell me to keep looking.

So many questions! so little time : )

thank you again for any replies we get

Posted Tuesday 26 Oct 2010 @ 4:17:54 am from IP #
Buzzman
Member

Most panels are EPS (expanded polystyrene) insulation sandwiched between two sheets of steel or aluminium.

As the steel is heavy, panel sizes are relatively small to enable ease of handling. Can be cut with basic power tools.

But are not cheap, and if available secondhand are probably damaged.

if you need to do something on the cheap, why not build a coolroom yourself? You can source EPS in large blocks (used for openings and penetrations in concrete slabs in the building industry which are cheap even if new.

First find a 240V plug in compressor that ca cope with the approc volume of the space you have to work in.

Build a shed using recycled or 'found' timber. Clad exterior in exterior ply (painted) or corflute - it only needs to keep water out. Waterproof roof with either waterproofing paint or tin roof or similar.

Line inside with plastic sheeting, carefully sealed, then EPS blocks inside this. Thicker blocks, better insulation (rule of thumb).

Attach strips of hoop iron to the studs thru plastic sheet, and allow them to protrude out past the layers of EPS blocks - sorta like brick ties in a brick veneer wall - then bend the ends of the strips over so they are flush with the surface of the blocks.

Then attach sheet metal or hard plastic sheet to the inside of this. Might be easier to use battens attached to hoop iron first. Seal joints and penetrations carefully.

Supply drain to take away any condensation, provide screens so insects cannot enter.

Attach compressor, install salgaved shelving, plastic tubs, whatever, plug in compressor and away you go!!

PS: Do not approach Council with this plan!!!!

Posted Tuesday 26 Oct 2010 @ 5:29:03 am from IP #
PV2010
Member

marcusmucus

As Buzzman alluded.... check your local Council's food storage guidelines before you begin construction, they can be a pain in the arse if your coolroom isn't up to scratch.

Posted Tuesday 26 Oct 2010 @ 10:59:15 am from IP #
marcusmucus
Member

hi Buzzman,

Thanks for such a detailed description, sorry to have wasted your time but i am planning on using the panels as i like the fact they are structual and ive just come off spending 8 months on another building project and i just cant loose anymore hair this year, so my tools are down.

So i have been told they use a modified circular saw blade (basically they shave the blade down to make a sharpened cutter) to cut the insullated panels?. anyone tried using a normal cicular blade to cut them before?

once again, thanks to everyone.

Posted Wednesday 27 Oct 2010 @ 2:10:04 am from IP #
LaSource
Member

It seems to me both retrofit and new builds have substantially different approaches available because existing systems have been built with cost and cheap electricity in mind. Also many commercial properties may have space limitations and reside within city heat islands. In commercial spaces you tend to see the adoption of one solution fits all, designs which are a balance of various factors (including cheap power).

Developing a low energy cool room may be quite simple but it may also be "unusual" which from experience our councils and government organisations are not very good at dealing with.

So lets take food storage and temperatures as well as the total volume required as the starting points and develop solutions that minimise unwanted inputs/Outputs and maximises the wanted input/outputs. Theoretically we could build a thermally suitable space with provisions to allow the scalable addition of efficient heat transfer and where necessary refrigeration according to the performance of our space (thus keeping energy low but allowing us to meet standards). Our space should include provisions for these add on coolers with the interference minimised (eg; Hot air output away from cool room).

Whilst this approach should support alternatives for Food co-ops they will also support the development of cool pantries and other requirements.

I like the idea of a insulated slab (Green Concrete) with shaded, straw bale walls, reflective and Infrared emissivity paints with usage features such as an entry airlock and waste height goods transfer windows (airlock). External night cooling of a fluid which can be pumped through the slab or chilled beams to reduce energy requirements further.

If I can get a good enough design I will build it.
Tony

Posted Wednesday 27 Oct 2010 @ 2:10:18 am from IP #
marcusmucus
Member

....and will you build us one too Tony? : )

Posted Wednesday 27 Oct 2010 @ 3:12:05 am from IP #
Buzzman
Member

One of the most obvious changes to cool room design is for individual 'bays' of shelving to be sealed from the main space.

In much the same way that domestic upright freezers rate higher for energy efficiency when they have solid plast drawers on each shelf rather than simple wire shelves or baskets.

When the freezer door opens, not all the cold air falls out on the floor, as it does with the wire basket types.

So too with commercial coolrooms. Haviong individual 'bays' that are sealed from each other even if only by a sheet of clear polycarbonate, and have doors to prevnt the loss of cold- dense air ever time the 'main' cool room door is opened, would mean the saving of a LOAD of compressor cycling time, and this is where I believe the main savings are to be made.

So marcumucus, I hear your pain, but the 'standard' 75-100mm thick coolroom panels will NOT provide adequate insulation for a cool room located outdoors - at lease, not for one hoping to run as efficiently as possibly.

You will need MUCH more insulation, plus all of the other suggestions made here - plastic strip door screens; separate sections etc etc.

And for cutting the panels, a standard "metal-cutting" sam balde is all that's required.

Their teeth are at a higher pitch to the standard wood-cutting blades, but are thinner, so can bind much more easily.

As Elmer might have said, be vewy vewy carefuw!

And plus 1 to all Tony's comments.

Mine were based entirely on your desitre to do it on the cheap.

So if you are resolute in your unwillingness to build a shed first, then once the coolroom has become a cubic structure, add 75X50 studs to the OUTSIDE of the coolroom, then add 75mm of additional EPS or Insulwool insulation, then a sheet of exterior plywood and a coat of paint.

Same on top, but use Colorbond or Zincalume on battens above the ply to proivide a 'tropical roof' effect with a clear space between coolroom and roof to help with conductive heat minimisation.

Even with the shade of the tree there will still be some sun and ambient air temp to conduct heat from.

Posted Wednesday 27 Oct 2010 @ 5:31:25 am from IP #
marcusmucus
Member

sorry to have hijacked this thread with my questions, but we are very much in need of a coolroom as the weather gets warmer. Thank you so much to all those that have contiuned to input, i will definetly consider adding a extra layer to the outside of the panelled box, (although i am unsure about how to real seal the new layer around the door).. anyway..

my basic question is about size, im considering 2.4 x 2.4 , or buying for the future and getting a 3.6 x 2.4...

What is the general rule of thumb to how much you can pack into a room, would a half full bigger room run the same as a very well packed smaller room?

what is the theories on how much you can pack in?

once again, thanks

packing a coolroom fairly fullk

Posted Saturday 30 Oct 2010 @ 6:23:53 am from IP #
amun-ra
Member

marcusmucus you are correct there is a blade made for the purpose of cutting panel we call them a thumper as they hammer the panel till it tears and also folds the cut to leave a safe edge for handling and the fitting or aluminium channel and trims.The floor is a very important part of the room so take special care to seal around the vapour barrier with loads of mastic I build coolrooms as part of my job. Be carful with second hand panel if its been taken out its usually for a good reason eg(stuffed)

Posted Saturday 30 Oct 2010 @ 9:10:30 am from IP #
Jeffbloggs
Member

marcusmucus
The smaller you make it the more cost effective and energy effective it is. Make it as big as you must to store what you need.
By increasing your exposed surface area with a bigger coolroom, you are increasing your energy losses or better said; heat gain from the environment. Compact storage (ie less wasted space because of ill fitting containers etc) of the cooled contents is a must, and limited, but still practical access (space) should dominate the design. Position your shelving around the room with just enough space in the middle to access the storage on both sides of the accessway. Ultimately the rounder (sperical) you make it, the less the exposed surface area, and the more interior volume. ie a cube is better than a rectangular box, pending your shelving layout(how many rows) and access requirements. Alternatively sliding shelf frames, like used in a library would be ideal, but can add some cost depending your shelf design/sizes.
Take Buzzmanns advice and put something around the coolroom, if it is not in a room of it's own. Nearly any building will improve the energy performance simply because of the radiative and convection heat gains from the environment.
Letting heat in is the enemy, not keeping the cool in.

Posted Saturday 30 Oct 2010 @ 11:17:09 am from IP #
Buzzman
Member

Most efficient coolrooms have an over-centre cam-lock on the door, or similar, which 'squashes' the soft rubber moulding on the inside of the door against the door frame and thus seals the opening.

The type that roll horizontally and don't have this type of catch usually leak around the corners, as they rely on the moulding simply deforming, rather than compressing.

For coolrooms, such catchs must have an interanl release mechanism to prevent people being locked inside.

But a plastic-strips-curtain in the doorway itself will help reduce the amount of cold air dunped every time it's opened.

Posted Sunday 31 Oct 2010 @ 5:40:57 am from IP #
LaSource
Member

A little side note on volume and surface area.

The volume increases faster than the surface area. The Surface area is where we will get heat gain.

If you may need to increase the size of cool room storage at a later date it would be wise to consider this at design time. Better enlarging the cool room than building a second one (thermally at least).

Perhaps you could build the larger room but only cool half of it with a fitted wall than can then be moved to increase the cooled volume (may present leakage). Until you increase the size you could use the spare space as an air-lock and perhaps invest less in its insulation and refrigeration until you really need it.

Tony

Posted Monday 1 Nov 2010 @ 7:55:53 am from IP #

RSS feed for this topic

Reply

You must log in to post.