Cooling a tin shed observatory in summer ?

cventer · #1 16-10-2005, 04:48 PM

Hello All,

I am looking for some ideas to keep the temperature of my garden shed observatory down in summer.

I have a tin shed type observatory with fold off roof and during summer temps get VERY hot in here and I am concerned abbot the health of my scopes and electronics which are permanently mounted.

Anyone have any good suggestions regarding possible methods to cool this puppy down?

I have had suggestions to use exhaust type fans etc… which I can do, but if someone else has a proven design I would be interested in how you did it.

I was thinking something along the lines of Solar panel, 12 v battery with regulator to keep it charged but not overcharged. Some extractor fans up high and maybe a temperature switch that kicked the fans on when temp is above a certain degree.

Any thoughts or suggestions?

Best Regards
Chris Venter

acropolite (Phil) · #2 16-10-2005, 05:21 PM

Chris, might be an idea to insulate the shed and provide some airflow with small 12volt computer fans. Insulation will minimise the heat buildup and some airflow through the shed will keep the temps down. The solar panel idea is OK and you should be able to drive the fans directly without a battery, that way if the sun's shining the air is circulating and there should be no need for a thermostat. Another technique I've seen on hothouses is to raise the roof a little as the temperature rises to allow airflow by convection.

ballaratdragons (Ken) · #3 16-10-2005, 05:31 PM

Chris, I had a small tin shed when I lived briefly on the Central Coast and it used to cook in there.

How I solved the problem was not to drag the heat out by fans but to prevent the heat getting in. How I did this was I attached 4" x 2" (about 90mm x 45mm in metric I think) lengths of pine to the top and bottom of the roof (1 foot over on each end). Then I ran 2"x 1" pine down and hung it over the edge about 2 feet. Then I simply stretched the heaviest grade Shade cloth (light colour) on the 2" x 1" pine and it kept the sun off the tin preventing it from heating up. Then I placed 4 vents in the walls. One on each side up near the top and one on each side at the bottom and that gave air flow. It became a nice cool garden shed on hot days!!

If the temperature happens to rise a bit inside, the heat rises and escapes out the top vents causing it to drag cooler air in the bottom vents.

h0ughy (David) · #4 16-10-2005, 06:02 PM

insulation panels would help chris, I have been looking into this for some time. there is a product out there that sandwiched foam between colourbond panels. I wish I could remember the products name (it was on backyard blitz). there is also a insular product made of foil and air pockets that you could glue on the inside.

ballaratdragons (Ken) · #5 16-10-2005, 06:08 PM

If you want to insulate the inside just glue sheets of polystyrene (foam) to the inside of the roof & walls! Even polystyrene sheet at only 20mm thick won't let any heat through. If you want to paint it black (Or any colour) just use waterbased paint.

Using the method in my previous post and the polystyrene idea in this one would make it feel almost like a fridge!!

cventer · #6 16-10-2005, 06:39 PM

The ,main issue I have is that the roof needs to be kept very light. My roof actualy folds open like a book and lays back on itself, I lift it via a pulley system, but I still need to keep it as light as possble. Foam may be the go on the inside

Where can I buy suitable foam in large quantity to do the entire roof and walls ?

Regards
Chris

gaa_ian (Ian) · #7 16-10-2005, 07:02 PM

Chris
I would try Clark Rubber or similar
Or look up "Foam" in your local yellow pages online
There are people out there who Die cut foam of all sorts to size

asimov (John) · #8 16-10-2005, 07:49 PM

I can vouch for Kens Idea..I used to live in a glorified tin shed in Lightning Ridge NSW & it doesn't get much hotter than that place!

Astroman (Andrew Wall) · #9 16-10-2005, 08:06 PM

Also paint the whole shed glossy bright white, the more you can reflect the better you will be. Why else would they paint Observatories white. Mine is bright white I can stay in there all summer. No fans either.

ballaratdragons (Ken) · #10 16-10-2005, 08:14 PM

Chris,

Polystyrene (Styrofoam) Sheets can sometimes be purchased at Building supplies, or Insulation companies but cheaper from a manufacturer. If you have no luck, signwriters have it as they cut foam signs out of it! (they probably charge more though).

The product from Building supplies and Insulation companies might be better than the signwriter version as it is often lined on one side with silver foil for extra heat reflection.

ballaratdragons (Ken) · #11 16-10-2005, 08:20 PM

Oh, and don't forget the air vents top & bottom. Essential for air flow! You can get really small ones which will work fine. They are about 5" x 2" and have insect screen on them too! I think I paid about $7 each for them when I fitted them to a caravan.

slice of heaven · #12 16-10-2005, 09:23 PM

All the above will help, depends how much your need for cooling can justify the cost.

The white external coat is a big plus regardless of internal insulation.
Air flow as BD suggested is a cheap addition , whirlybirds work well.

A roofing blanket and batts would probably be my choice if you can remove your roof sheets and refit.
Sisalation (reflective foil with insulation attatched) is cheap and reasonable, its finished look will depend on how well it's fitted.

For styrofoam sheets I'd recommend the blue high density sheets for effectiveness.
There's a variety of products incorporating sheetmetal with insulation attatched, but expensive for one off, small projects.
Purline is a corrugated sheet with polystyrene attatched, ideal for roofing, easy to fit and with a great finish. Bondor (coolroom panelling) is a flat sheet polystyrene sandwich.

A word of warning about polystyrene though, it WILL retain heat once it's heated and will radiate heat back for hours after the sun goes down. The thicker it is the longer it takes to cool off, the thinner it is the less effective it is at keeping the heat out. NOT a recommended choice without an aircon or refrigeration unit.

Check out major the Insulation companies for something that suits your budget.

ballaratdragons (Ken) · #13 16-10-2005, 09:29 PM

The previous advertisement brought to you by 'Slick Insulation Company'

avandonk · #14 16-10-2005, 10:05 PM

I am in the throes of designing a garden shed (observatory).All the previous posts are correct to a degree (excuse the pun).There is nothing you can do to lower temperatures below ambient without an active system ie aircon!All you can do is have a high thermal mass and limit the incoming heat.This lowers thermal shock.If I feel uncomfortable then what is that doing to my optics!
A garden shed should be seen as that,temporary respite from the elements on the night!

Keep all the valuables where they belong where you are comfortable.Nice and dry and not sweating!And they can watch the telly!

Bert

By the way I am the only bloke for miles around whose house is his shed!

astroron (Ron) · #15 16-10-2005, 10:28 PM

I have had my observatory lined with polystyrene and sheets of ply and also ventilation for about 15years(built the observatory before the house) and the scope is always nice and cool even in Queenslands hotest days.astroron

cventer · #16 16-10-2005, 10:42 PM

Im not worried about cooling lower than ambient. Most days are around 29 - 34 degrees in summer. If the temp stays this hot in the observatory then I amnot worried about equipment. Its when I see the temp inside edging 45 - 50 that i get worried.

The whole point of an observatory is to leave your gear setup so you can get observing or imaging quicker. If you pull your scopes and camera off each time you would in my case nearly an an hour setup each time to get scopes on, counterweights on. Cables conected to DSLR, SBIG, Robofocus, Optec TCF focuser, dew heaters etc..., Scope balanced, pointing model rebuilt etc.... Just too much hassle not to mention the chance of stuffing it up , so my goal is to get the temp to an acceptable level.

I guess I could buy one of those Portable humidifier type airconditioners for summer and let it run. Power bill will be huge, but hey the scopes will be happy.

I think I will paint the roof white for starters, add some more ventilation top and botton, Add a couple of bathroom style exhaust fans up hig on the wall on either side and see how I go. Next stop after that is foam.... I Cant paint whole shed white as wife will object...

Best Regards
Chris

ballaratdragons (Ken) · #17 16-10-2005, 10:50 PM

Chris, are you able to grow plants around the shed? Plant shadows on the walls can actually drop temps inside sheds too.

astroron (Ron) · #18 16-10-2005, 10:58 PM

You only need the insulation to keep the air inside to ambiant temp during the day, then when the sun goes down off with the roof and let it cool with the night air.No need for all the electric gizmoes, a wirlygig for ventilationif you want. astroron

slice of heaven · #19 17-10-2005, 07:02 AM

Quote:

Originally Posted by astroron

I have had my observatory lined with polystyrene and sheets of ply

The ply is a good choice , wood is a great insulator.

Painting the roof white and adding ventilation will be a good start for minimal cost.

rmcpb (Rob) · #20 17-10-2005, 08:38 AM

My shed I keep my scope in is simply insulated with the roll out insulation material the roofers use under the colourbond roofs. Its easy to hook up, has a foil back to prevent bits from falling and really helps with the heat. I extended the eves over the edge of the shed to stop the walls getting blasted and have found they do not need insulation.