Use Combination of Strategies to Cool Your Space




About: I am an artist/designer and run a small business called Minifacture, advanced fabrication lab. I only approve good food, good beer and good making.

As an art school graduate, it is almost natural to have no stable source of income. I have a studio on a top floor of an old brick building, and because the rooftop gets lots of sun all day and there seems barely any insulation between the ceiling and the rooftop, heat dissipation really kills me in the studio in summertime.

Yeah, turning on AC all day would make the space much more livable but that would use so much energy wasted if I don't do anything about the sizzling rooftop.

So here it comes: Passive, No tech(almost), cooling for rooftop and the space below.

It is a very simple and cheap(to make and to use) i'ble, and you can apply to pretty much anywhere with large surface area for evaporation!

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Step 1: Science Behind This Simple Project

This i'ble uses the principle called "evaporative cooling". When liquid turns into vapor it requires energy - in this case surrounding heat - and where the liquid evaporates is left with cooler temperature. This passive technology has been used for thousands of years, and still being used in many applications. Misting and evaporative coolers are good examples of this. Also your body sweats works the same way biologically as sweat dries out, surface of your skin is cooler. Rubbing alcohol evaporates much faster than water, thus it feels cooler when you blow it on your skin.

For more information for you curious heads, check out this Wikipedia page.

This video explains evaporation process concisely.

Step 2: Mateials

I had 4 meters of 19mm ID hose laying around so I started from there.


4 meters (16') of 19mm ID flexible hose

10 meters (33') of 16mm ID flexible hose

3mm drill bit

a few zip ties

(optional) hose clamp, if you want to detach the hose quickly.

hose adapters (3d printed)


I bought 16mm hose because it is cheaper than 19mm and the weight of the water it has to hold is less.

Total cost of material is around $10 or less.

Step 3: Drill Water Outlets

I used 3mm drill bit and made a thru-hole every 30cm (1 foot)

If the holes are too small (also in quantity) water pressure inside the hose can get pretty high and burst at some point. If the holes are too many and large, water may not get till the end of the hose, so don't make too large or too many, you can always make more if it isn't enough.

Step 4: Hose Adaptor

These are hose barbs and connector to a shower head in the studio.

Barbs diameters are 19mm and 16mm, and thread pitch is 1.7mm.

Printed with ABS and PLA with 0.2mm layer height and they work great.

Step 5: Connect Things Where It Needs to Be Connected

Use zip ties as hose clamps.

Check water pressure and adjust number of outlets.

Place hose strategically to cover most area. In my case, rooftop is very uneven so I placed it on the highest spot to let water travel the most area.

Step 6: Results

15 minutes after watering (for 3 minutes) temperature dropped dramatically. I didn't expect this much of temperature drop but it works pretty well.

Thanks for reading!

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    13 Discussions


    3 years ago

    You should get some white foam sheets and lay them down with some weight to keep them in place. Reflect the suns energy back up plus it adds a little insulation haha.

    3 replies

    Reply 3 years ago

    or go even cheaper and paint the roof white above your studio


    Reply 3 years ago

    maybe I should offer the landlord this. It may be one of the best solution without having to cause too much trouble in my case.


    3 years ago

    As many of you have good point, I should have mentioned this i'ble
    only works for specific condition which I am in. My studio is shared with 3
    other people, and I know the person who is a relative to the landlord.

    The landlord isn't really interested in keeping a good shape of
    the building nor want to rent out and make monthly income. There is complicated
    ownership among many relatives and thus half of the building is empty. I was
    lucky to rent a studio here for dirt cheap, probably only until the soon-to-be-done
    new development of the area

    The building does not have any insulation, and it was built on
    the fly, without any plan and blueprint. This type of practice was common during
    super rapid industrialization in Korea back in the 60s(which this building was
    built) and tens if not hundreds of neighborhood has been brutally re-developed
    only following the rules of profit and efficiency for the past decade. This
    neighborhood has recently gone through the decisions for gentrification but
    still no one knows when and how since there are lots of unoccupied
    buildings(uninhabitable) and the price of the land is around U$4000 / sq.ft. due
    to its good location in the city.

    Building anything on top
    of the roof requires going through changing of building registration which
    requires blueprint of the building, as well as landlord’s inclination. And yes,
    water isn’t free but it would be more efficient with a little help of passive
    evaporative cooling, than constantly cooling uninsulated space with direct
    sunlight, with A/C which won’t really cool down much. Also evaporative cooling
    obviously requires evaporation, and what I had to do was to let water run for
    3-5 minutes and let it dry.

    Here, electricity is
    owned(and monopolized) by the Government and the consumer rate is punishingly harsh for heavy users(over
    500 kWh/month), charging around 50cents per kWh compared to US average 12cents, for average US household usage(911kWh). For 911kWh it would result over $400 per month( There are many reasons for the high costs of consumer electricity but one of the main contributor is that the vast majority(95%) fuel (coal, natural gas, oil, and nuclear power consist 96% of total production( to be imported from overseas(

    In contrary water is locally sourced and plentiful(huge Han river across Seoul) thus the price is low. I did not run
    the calculation side by side since this I’ble was just a simple poor man’s way
    of cooling but I am almost certain A/C wouldn’t cut it in terms of energy
    consumption in this case.

    So much to talk about,
    but I wanted to answer most of the comments here. Anyways thanks for great
    ideas, inputs and comments! I could be wrong so leave a comment if you have
    anything to say. Thanks!


    3 years ago

    Why don't you try recycling old plywood and build a deck on top of your roof.

    If you leave about 3" clearance you would be forming an air chamber that will only transfer heat radiated by the plywood and little to no heat by conduction, mostly because of the convection that will be present in the false chamber.

    here is a little sketch

    1 reply

    3 years ago

    the only thing you conserve its your money, that water is not free. its made in factorys (allso you can have a pump in the basement for adding presure)and paid by the landlord and the other tenants.... The fact that you have your own/rent a studio... in a city... tells me that you make some money...

    If its yours. or if you plan to work there for a wile talk to your landlord for fixind the roof (the green membrane seems worn) maybe some insulation. better windows or shades, or reflective films for them, and yes a inverter type AC 12k btu its a good size (hi-end one cost 600usd) . 4-5Kw'h, in the worst case, when your windows are bad and "leak" it will work at fulll capacity so'(i don't know your kw price ) In my city for a consume of 40Kw i'l pay ~5usd per day... If you can't offord that well.... you know move:) down size-or invest.

    The evaporating cooling its not new, but you must ensure you have "some things" like perfect lining,much better water management ( pipe nozels. a"computer"). Some irigation hardware its nice, and maybe, maybe you manage to transorm it into a green roof/ roof garden.

    1 reply

    3 years ago

    as many have previous said, water is very dangerous and it can introduce risk of rust in RCC roofs. i.e reducing life of it. I had the same situation, I limewashed the top. It was a Huge difference, one can feel by touching limewashed and bare concrete. also now it radiates no heat in evening (compared to bare roof)


    3 years ago

    Adding to my collegues considerations you must keep in count that water can be very dangerous for roof integrity. Keep a surface humid for a long time can keep to disgregation depending on the material itself is composed. If your roof is cementified i think is not a good idea to keep it wet.


    3 years ago

    While this is an interesting approach to keeping the roof
    and your studio cooler, there are other more economical and environmentally friendly
    choices that would be better than to waste a precious resource as water. Such as cover the roof with white paint, which
    could be picked up cheaply or by asking a contractor(s) for their remains after
    they have finished a big project or even place an ad asking for leftover white
    paint. Of course you should seek
    permission from the building’s owner or management company.


    3 years ago

    Water ain't free either. Better is to have a roof garden/grass/etc.