Heat

The last couple of days have been particularly difficult.  A weekend, but it might as well be a week day as I can’t do anything that I had planned anyway – too hot.

So I decided to run some tests, to see what is going on.

First, current Bureau of Meteorology reports:

Frankston 19.6oC, Cranbourne 21oC, Melbourne 27.5oC

Local temp in the backyard: 35oC.  And this is not the hottest time of the day yet – Melbourne is expected to reach 39oC, 12oC hotter than current.  Wonder what my backyard will be then?  I expect we will hit 44-46oC locally, as has also been the case in recent weeks.

The sun is currently beating on the northern and eastern walls of the shed.

External Shed Conditions:

Ambient: 35oC

North Wall: 52oC
East Wall: 46oC
West Wall: 37oC
South Wall: 37oC
Northern PA Door: 56oC
Southern PA Door: 36oC
Roller Door: 55oC

Internal Shed Conditions:

Ambient: 31oC

North Wall: 34oC
East Wall: 39oC
West Wall: 34oC
South Wall: 35oC
Northern PA Door: 50oC !
Southern PA Door: 35oC
Roller Door: 46oC !

So what are the take-aways from this?  First, overall, the insulation is achieving some degree of block to heat transfer directly through the walls.  It could do better, but it is not the weakest spot in the shed.  I didn’t bother assessing the mezzanine area – there is a lot of heat buildup up there – probably a good 5-8oC higher, which would have been assisted if the whirlybirds hadn’t disappeared off the materials list at some stage in the process.  I’ll probably have to add a couple back on at some stage if the upper area is ever going to be useful (in summer) for anything but storage.

The eastern wall (given the time of day) is still showing the effects of the earlier morning sun, so the limit of the insulation was exceeded – it being a 39oC radiator into the shed, pushing up the ambient temp.

The weakest spot is definitely the doors – each being like having a 50oC radiant heater sitting there.  The PA door is hot and is a compromise to the boundary, but it is the roller door that is really letting the heat through.  If I ever expect to get any control over the shed conditions, the roller door issue will need to be addressed.  The PA doors can at least have insulation attached to them.  Surprisingly, the window did not seem to be a particular cause of issues – anything that was near the window and exposed to direct sun of course copped it.

Air conditioning the shed is not an option currently – the size of the unit required is a bit too expensive to think about.  I do wonder if an evaporative unit would make any difference?  Increasing insulation on the shed walls would also be an option, but only after some of the lower hanging fruit has been plucked, and the cost (and lack of ease of insulating after construction) will also be a real factor.

In the meantime, the shed is 4oC below external ambient, not exactly the 10oC I was told to expect.  And that is without the insulation compromised further with laserlight.

That may be currently workable (just) (although as the day progresses, the heat will continue to build), but I can’t do any filming out there – dripping in perspiration is not exactly the look I want on camera!

How have others solved the heat issue in their sheds?

22 Responses

  1. Hi Stu,
    I built a lined shed with timber frame so don’t have the heat issues compared to an unlined shed. When I lived in Melbourne we had an evaporative cooler in the house (and connected workshop). On a 41degC day it was 24 degrees inside the house, an astounding result for something that costs almost nothing to run compared to a refrigerative aircon. If I lived in a place where hot days are almost always dry days (like Melbourne) then I would have another evap in a a heartbeat. In Qld however I have a 25kw 3 phase aircon, just as well I have a roof full of solar cells.

    • Thinking the house evap needs an upgrade – the unit is too small for the house. Might find itself on the roof of the shed!!

  2. I whole “heatedly” agree with the roller door issue. …”like having a 50 degree radiant heater”… I have two facing west. In the arvos with them open, shed is about the same as external temp.

  3. To reduce the heat from the roller doors, I did two things:
    I glued this stuff from inside the shed: http://www.amazon.com/Reflectix-BP24050-24-Inch—50-Foot-Insulation/dp/B0009XCJA2/ref=sr_1_2?ie=UTF8&qid=1391307160&sr=8-2&keywords=buble+insulation

    I also, added a shade cloth outside the shed, so that it creates the shade on the roller doors, and this helped quite a bit.

    • Forgot to say that this bubble wrap insulation on the back of the roller door does not create any problems for opening or closing the door.

      • I was thinking that might work – just the roll becomes a bit larger in diameter – not a problem for my install.

        • I would have had some left over insulation (an entire, unopened roll) from the shed build, but it seems to be a commonly accepted practice that the builder gets to take any left-over materials that he wants after completing the job. Can’t say I understand that personally – if material has been ordered (over-ordered), then that belongs to the job as far as I am concerned, and the shed owner. If they clearly do not want any left over that is one thing, but otherwise simply taking left over materials (including a full, unopened roll of insulation), that the owner paid for and would want to use elsewhere, well, what is that?

          • Has always been the way. The supplier only supply enough to build. If over supply it goes back. If they had under supplied, due to the builder cutting it wrong or wind damage for example, they would have sent a new roll out pronto.

          • Ah – that makes sense. It wasn’t clear from all the calcs and costings etc if the final supply list had the same quantity of materials as the quote. Presumably they are a little different then, so there is that possibility that there will be an oversupply, and in that case it makes it perfectly legitimate for it to be taken away on completion of the job. That is also a good thing, as it means as a purchaser you pay for the shed, and not for the materials supplied. If they want to overorder to ensure everything works smoothly on the day, that is their prerogative (and it only eats into their cost margins at worst).

            Thanks for the clarification Dave!

  4. Yes, Stu.
    It’s Don from Perth here. I had a colour bond shed with a wall height of just 2010mm. I had it lined with styrene foam sheets overlaid with 9mm MDF sheets. There was a reverse cycle air cond at 3000Kj cooling. It wasn’t adequate at all mate. I said “had” above, speaking in the past tense, because on 12th Jan, a rear neighbour’s tree fell across our place, wiping out the back wall of the house, a large patio, my fence and my ENTIRE shed. It was at 11:45 pm. Hours earlier I was at the bench clamping up boards in the relative cool of the evening. I am lucky. All insured . Nine machines were crushed and splattered. Repairs take lots of time. Most machines are unserviceable. My soon-t–be new shed will have a wall height of 2745mm and an air cond at 5600 Kj cooling at least. Walls and roof will carry insulation. Not a fun time here at moment. Good luck with your projects mate. Don.

    • Bloody hell – that is a pretty poor result. Even the idea of a machine being “splattered” – must have been a hell of a tree. Sounds like even machines that are serviceable should become the property of the neighbour, and he owes you a whole replacement set. A tree that decided to take revenge on a shop that chops timber – bet that tree will be found in many projects from here on!

      I’ve been carefully documenting each and every tool and machine that ends up in the new shed for insurance purposes. No way I’d be in a position to replace the workshop if the same thing happened without the backing of an insurance company.

  5. I have a brick garage with a tin roof that I have just retrofitted with Super 15 Foil Board. It made a big difference, however when I walked up to the front of the shed that faces north and has a roller door, the temperature escalated and the door is impossible to touch on these 40+ days. The solution for me was to drape a piece of 90% shade cloth in front of the door. Not a very elegant solution some may say, but it is one that I can live with, and at least I can touch the back of the door and not burn my fingers now, and it does substantially reduce the temperature inside the shed.

  6. Yep.. My dad did the same with roller door. It has had the insulation on it for a couple for years now. amazing the difference it made..

  7. The main problem with evaporative is that they use water to cool down the air therefore blowing damp air into the area to be cooled, this would play havoc with the moisture content of any timber in the shed

    • Was a bit curious about that, more for the machines (CI) than the timber. On a hot day when evaporative would have any effect, temperature is through the roof and humidity is through the floor – that’d play havoc with any timber out there anyway I’d have thought?

      • It would effect anything you build while the timber has a high moisture content, the ideal situation is to make something in as near to the climatic conditions at its in use location (about 2% diff max) otherwise you will have expansion/shrinkage problems as the item adjusts to the new conditions. Timber never dries out, it always has a moisture content of one level or another even after a finish has been applied

        • So having an evap cooler in the shed is actually a good idea then, considering the items, once finished, will be going into a house with the same 🙂

          I normally simply do not have the luxury of matching shed conditions to house conditions, either in timber storage or while making the items. Fortunately through good luck or good planning, I haven’t had any adverse results from excessive timber movement.

          My sheds have always been little hot houses, with wildly varying humidity conditions depending on the weather and time of year.

  8. I have enjoyed all comments here. Currently am in shed as light breeze gets shed temp (down) to 30 degrees internal and external. ( Warragul) I suppose there is a lot of latent heat in my rolled-up shed doors?

    All shed orifices are open. Am looking for a min. over night temp of about 16 degrees around 6AM. I’ll go to bed then. Lucky for some!

    • Unfortunately here, by the time it is cool, it is too late to do anything without disturbing the neighbours.

      In time, I’ll have the lathes up and running, and as they are quiet machines that will give me something to do!

    • shed is cool. … with a few bugs… I’ll be here until about 10am !

  9. I just use a fan – works for me.

    • Not so good when filming however – creates too much noise. Tends to be my option too when I’m just out there doing my own thing.

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