Natural Air Conditioning

Sorry if this is the wrong forum. Wasn't sure where to put it.

So it's 40C (104F) here the past few days. If often goes up to 48C.
I'm wondering what more I can do to keep my house cool without AC. I have a solar system, it's good but not enough to run AC.

I live in an old stone barn, 2ft thick walls, single storey with a 2-layer terracotta tile roof. Built directly on the bedrock. The sun beats down on the roof all day, so by 4pm I'm suffocating. I spray myself with water and have a standing fan, which is nice, but by 4pm the humidity from all the water I'm spraying, plus me and the dog panting all day adds to the swampiness. The sun doesn't go down until 9pm so there's at least 5 hours of sweltering I have to go through before I can escape outside.
I leave the window and door open all night but it doesn't cool down much. Morning temp outside is 15C, inside it's 25C.

Option 1 is 5cm cork insulation sheets on the ceiling. It's expensive (1200 EU total) but I'm told it's worth it. It will take me until next summer to save up enough.
Option 2 is to knock in another window for ventilation at night. Cheaper by half, but this won't really help me at 4pm though.
Option 3 is to cover the walls outside with clay. But that still leaves the roof to get baked.

Anyone have an opinion on which option will have the most affect?  I'll probably end up doing all 3 eventually, but that will take a couple years so I'd like to know which one would be better to do first.  

I can't start any of these projects until the winter, so in the meantime, if any of you clever folks have any tricks for how to keep the house cooler during the day I'd really appreciate it.  

40 C?! Yuck. I complain if it hits 35. My AC free apartment dwelling aunt in Europe very carefully manages heat like that with windows blinds, windows open on the cool side, and fans to keep cool - but doesn't have an uninsulated roof above.

Roof insulation would be my preference for that situation. Having lived in houses with good and poor roof insulation - it makes a massive difference in the summer. Also shutters or blackout or insulating blinds/curtains for the windows during the day.

I wonder if rolls of that reflective insulation ( brand name here is reflectix) would help? On the ceiling or cut to fit the windows on the sunny side?

Does the insulation have to be natural? Would foam board or fiberglass or rock wool insulation be cheaper than cork? R value is really what you are looking for.

Could you get a ceiling fan? I find them far more effective in keeping me cool than even several floor fans.

Could you whitewash the house and possibly even the roof - white tends to reflect light and therefore be cooler.

For night time ventilation, if you decide to knock in another window, I would suggest making it in a place that allows you cross breeze between it and an existing window.  Do you have a vent near the roofline or a window that can be opened to allow hot air to escape at night, and encourage cooler outside air to be drawn in through the lower levels?  

This stuff webpage
Works great covering our hot hot south patio. If you could manage to attach it to your roof, and extend it out past the roof a ways it might help eliminate a lot of the solar gain during the day.  It's kind of expensive but easy to work with and I've used it several years with no degradation by UV.
Actually the link I gave goes to some that is 70% block, mine is 90%.

We also have outdoor curtains made of it on all south and west windows. And we only open windows when outside temp is equal or lower than inside.

Hi Anna;
I Agree with Catie;   The roof is your weakest link in trying to stay cool.
Adding any insulation there will be the most effective use of your money and time.
An extra window or two would be very nice but with two foot rock walls the labor/cost is not cheap.
Heavy curtains and a ceiling fan, will help as well.
Depending on the cost ,shade cloth would certainly deflect some of that heat.  But not if it blows off every time the wind picks up.
How bad is the humidity?  I suspect it is high.  
If the humidity is not to bad then a swamp cooler (evaporation cooler) could help and they use little power so your solar set up could run it.
You can make your own.
Do you have a good supply of nice cool water? Water dripping on a burlap curtain (or any material) with a fan behind will produce a cool breeze.
Channeling that water away and out to a garden or just a good drainage point is the challenge with a home made evaporation cooler.

I feel your misery. We have a small log cabin with awesome western views... we also can get the high heat that by afternoon can be sweltering.  Thank goodness there is little humidity here!
We do the best we can, by opening all night, using fans to transfer the air. heavy curtains indoors and roll down shade cloth on the west facing windows,  ceiling fans.
Someday's its just too hot and there is not much to do about it. If you can go swimming, if not then light airy clothes and stay in the shade outdoors until it cools enough to stand being indoors.

thomas rubino wrote:Hi Anna;
Depending on the cost ,shade cloth would certainly deflect some of that heat.  But not if it blows off every time the wind picks up.

It is expensive, at least for me. I made a net with about 2' squares of polyester cord, also UV stable and have two layers one above and one below the cloth like a sandwich. The cloth is attached between them with short pieces of cord tying the two nets together. At the edges the two nets are joined and used as the tie downs, all the stress is on the nets, it's handled some pretty strong winds.

I've lived in a similar environment now in three houses on concrete pads made of masonry, with and without a concrete structure under the roof. The difference is night and day. Whatever you can do to insulate yourself from the roof will really make a difference, whether that is cork or anything else. Not sure what your winters are like but it will probably also help you keep your heat inside your house when you're cold.

Your house is beautiful!  There are a number of good ideas here that I do not want to repeat. So to go in a new direction, have you considered a reflective coating  for the roof?  I am not suggesting to destroy those beautiful tiles, but rather a space blanket like tarp to tie onto the roof....or portions of it.  On a much smaller scale, I have had success using a space blanket as a tent fly when hiking I  the desert.

How is your water supply? Running a sprinkler on the roof does AMAZING things for lowering temperatures, even in higher humidity.  

Hi R Scott,

Good point. That takes us to the possibility of a swamp cooler.

I studied a few examples of those coppo roofs to understand how they are constructed, but I had trouible getting a clear image of same.
Your roof looks new and may have been constructed with ventilation built into the roof structure. Coppo tiles were used to create an airflow under the tiles.

However, if its possible to get inside the roof and see if battens are exposed, you may be able to fasten reflective sheet under the tiles.
You need a gap of about 2 inches for the material to reflect well.

Then install wool type batts [ earth wool, fibreglass, wool ] insulation on the ceiling as thick as you can afford. I use 300mm depth of the batts.

I live in Bendigo, Australia where 40 C is common in summer.

If there is a cavity in the roof, a powered roof vent will ensure built up heat will be drawn out during the day and at night.
Mine are operated thermetically, in that when the cavity temperature gets to 25C they come on and stop when its below 25C.

The construction of a middle eastern style wind tower  will also help.

You have heat gain during the day from the sun and heat lost during night from the colder air.

I would reduce heat gain during the day by:
1) shading all the walls and windows on the outside with trees/shrubs/curtain/etc
2) painting the roof white, spraying water on the roof, having trees shade the roof esp in the afternoon.
3) removing the hot air at the top of the house with some type of chimney/fan/vent
4) venting the bathroom and kitchen, so that the humid air goes directly outside vs spreading to the entire house. likewise for hot air (oven/stovetop/shower/etc)
6) Increasing the airflow during the night esp at dawn when the air is coldest, can you power a fan from the solar battery
7) Maybe spray the outside wall down at night with cold water so that it can quickly lose all that extra heat.

Perhaps you can give us a few more details of the building.
I have experience that may help.
Some questions;
- Do you have to keep the exterior stone walls as they are?
- Do the walls allow moisture to enter the house?
- Do you have any roof space or a pitched, triangular roof?
- Are you handy with hands?
- Can you shade the walls easily?
- How does the sun hit the house as the day passes/
  - from the side, across the back [low wall] to the other side?
  - Or from the side across the front taller stone wall?
- What temperatures do you get inside of hot days?
- Does it cool down every night?
- How tall are the ceilings?
- Does the ceiling have concrete beams running one way and terracotta beams inserted
 on or into those beams running the otherway?

Stone walls by their very nature bad news.

From Building with stone, problems
"The reason is that with so much uninsulated thermal mass, the house tends to take on whatever the average temperature is outside and just stay there...so in the winter it will be very cold,
and in the summer it might be very hot. The way to overcome this is to add a layer of insulation in the shell somehow.
This can be done in various ways, such as making a double stone wall with an insulated cavity in the middle,
or by putting insulation over the stone (preferably on the outside) and applying a stucco or plaster over this. "

In Australia with a dry heat I use a lot of shade, so if you house was here I would initially shade each wall that faces the sun with shade clothe.
It would be fastened at the top of the wall and be fastened to the ground say 900mm to 1-5M from the wall.
This will allow breezes to pass the wall.
Assuming you cannot attach anything to the roof because of laws, high winds or for cultural reasons, the roof lining I spoke of earlier with insulation over the ceiling.

I would then add a venting system to get hot air out either during the day  and / or at night.
The best systems use electricity and really cause large volumes of air to move. The ones that rely on wind, luck or heat thermals dont usually work at night and do not move a lot of air.

I use a lazer thermometer and measure and record in a diary what is going on, to track improvements with their effect.

I have assumed a few things;
- you cannot paint the roof
- electricity is available
- you can carry out some tasks yourself
- you cannot spray water around, or dont want to.
- you cant wait for trees etc to grow.

If you lay a drip hose along the peak of the roof, it should help a lot. I know someone else said to use a sprinkler, but I've had trouble with the water finding gaps that rain misses, because the sprinkler was sending the water in a different direction than normal. But a drip hose should work without causing leaks inside.

I am no "expert" here but, I have seen and felt the following idea work in real life  I have used it in a desert environment AND it is very simple.  Terra Cotta tubes dripped with water early in the day is passively cooled with air dynamically moving through the tube by convection.  The previous mentioned convection causes air movement and not only is natural but quite satisfying.

Here is a link to one version, anyone can create their own improvements:  https://www.treehugger.com/low-tech-terracotta-tube-air-conditioner-ant-studio-4858405

We have a similar problem, we have a/c though our machine room doesn't have any a/c.  Weather forecast is "excessive heat warnings" with triple digits.

Our problem is all the machines are starting to overheat. If the one for our phone system goes out we will be without any phone service.

I suggested freezing bottles of water, then have a fan blowing over the frozen bottles.  That would help cool the room.  This might be something that might work for you.

Here is how to make a DIY swamp cooler:

https://www.instructables.com/id/Swamp-Cooler-1/




Here are some pictures I found on Pinterest to give you some ideas:

a couple of good ideas here use of shade sails to shade the roof is always a good idea. Because you are in a stone building one thing that comes to mind.. plant a lot of Vines so the vines will climb the walls an eventually onto the roof.. It creates a wonderful micro climate. make sure you do irrigation so the vines always have enough moisture to expire around the house.  I would also recommend if you can putting up a radiant barrier as mentioned a couple inches from the roof. Best if you have great ventilation at the soffit level The heat will find its way out.  Last couple of things.. put up netting and loose blow in about 2 ft of cellulose insulation(it cheap). Then put up some sort of sheet goods like sheet rock .. get it well sealed around the perimeter of the walls your walls already are pretty tight being 2 ft thick.  Between everything you will be able to let your ac do its job.  Do not know how big your house is.. but where you are likely have high humidity.  Running a dehumidifier may also have a major impact.

I just had a crazy idea: what about using a sprinkler hose to drip water down your roof? The evaporation should cool your roof tiles significantly.  Very cheap to do if water isn’t too scarce where you live.

Your house seems so right for keeping cool except for the roof. Nice thick walls!  Stone!   I have a metal roof on my little Tuff shed. I put R Max Foam board insulation between the 2 x 4's on the roof and the walls, and it made a big difference!  It has aluminum foil on each side, which helps too.  But I do still deal with muggy heat by late afternoon.  It was over 100 for over two weeks here in Arizona, which may sound normal for Arizona, but I do live in the high desert.  Over 100 is not the norm at this elevation.  I use a double layer of Reflectix, covered in Tu Tuf, a white inert vapor barrier type of plastic, by Sto-Cote, to block the windows, whenever the sun starts to pour in.  I rotate them and open and close windows accordingly.  Lots of Round Robin'ing!  LOL But it does help!  I too, have a little dog, and drench myself, in hopes of maintaining some form of cool in front of my fan!  I think cool thoughts and drink lots of ice water.  :)

Don't get me wrong, I am very grateful for each season.  I am also grateful when we move on to the next one!  LOL

Fickle Creatures Aren't We!  :)

There is a "silver mine*" in Missouri Ozarks that is a natural for AC and heating. The "mine" started from the bottom and followed a slim silver vein up the hill - until they decided to attack it from the top. The resulting tunnel is about 300' long. At the bottom during the heat of summer, there is a chilly breeze coming from the opening all day. From the top, during the winter, there is no snow around the top opening because of the heat rising from it.

If you have a hill, it might be interesting to burry a pipe bottom to top deep enough to capture some ground transfer.

RileyG
*@37.5527778,-90.4372222

The trouble is you probably have more cold than heat so doing things to accommodate the heat would be counterproductive for most of the time. We're in S. FL and when we added radiant barrier in our attic, stapled  to the beams, it made a huge difference.  Now we have a white metal roof and that does most of the reflecting. But now, in the winter we don't have the benefit of warm air coming in from the attic.  No matter because heat is more a problem here.

Could you temporarily attach radiant barrier under your tile roof somehow?

The original poster hasn't responded to any of these suggestions, lots of them good!

I don't think a radiant barrier placed on the inside of the roof will accomplish much. Keeping the heat out of the massive stone walls and roof is the primary goal. Whitewash is a very inexpensive way to start, I just don't know if it will "stick" to the roof tiles. It actually reacts with masonry to chemically bond to the surface, so if it will, it is a durable as well as inexpensive way to increase reflectance. Lime + water and a pinch of salt is all that's needed to make whitewash. We whitewashed our stucco walls in Wisconsin and it did a great job.

That's not enough though. Inside this stone house the ceiling appears to be the gabled roof. I would install a flat ceiling at whatever height, be sure the attic area above it is well vented, and insulate the new ceiling with 30-50cm of loose fill insulation. This is the single biggest improvement that could be made to reduce overheating, and to reduce the winter heating need as well.

If it is possible, insulation on the outside of the west, then the south, then the east walls would be the most productive order in which to proceed for improving interior living conditions. Likely to cost more than the new interior ceiling with insulation above it.

I would be installing some 600mm roof whirlybirds to extract heat from inside, if you can run some metal duct from beneath some trees to lower bottom of external doors so as to keep airflow through the house, then when you have the money, remove the roof and install 100mm reinforced Hebal ceiling then reinstate metal roofing with 100mm rock wool insulation underneath and reinstall the whirlybird vents, but you will need to make sure you get flow through ventilation

echoed:

👍Do you have a vent near the roofline or a window that can be opened to allow hot air to escape, and encourage cooler outside air to be drawn in through the lower levels?👍  

If the indoor air temperature at ceiling level is higher than the outdoor air temp, you need to vent your ceiling/attic, somehow... even if it's just a cross-breeze between opposing vents or upper windows. Otherwise, you are living in a Dutch oven.  

At night... you've got a usable Temperature Differential? Use natural convection:
Once you have a high vent/window open, after sundown, when ground level air is cooler than your indoor air, bring that cooler air in... keep it cool... bring it in through rooms that get no outdoor sun exposure to their walls, roof, whatever.

[Passive Annual Heat Storage] is something to research for ideas. New or renovating construction... Trombe walls... whole systems using underground airways using the thermal mass of the soil to dissipate heat, return cool air...

Good luck!

Someone else has already mentioned nets across the roof and then growing vines over them to create shade.  This can also give a great crop of cucumbers, beans etc if you can get them off the roof.

The other solution that comes to mind if you have some land around the house is to dig a trench about 2ft deep and about 60ft long and line it with a tube that come up inside the house.  The air pulled into the house through the tube is cooled by the time it reaches the vent inside the house.  Bill Mollison covers this in the Designer's Manual and I think he used it a lot in Africa.  My Designer's Manual is in storage right now or I would give more precise details.

I'm wondering why radiant barrier wouldn't at least stop the heat coming in from the roof. We have a walk-in attic (rare in S. FL) and before the radiant barrier we could feel heat radiating from the ceilings.

My parents installed some misters along the roof of their carport. I was AMAZED at how much cooler their garage was and how even that little bit of mist kept the people cool too!

Maybe soak the roof tiles with water and cover with live sod? Keep watered with drip lines.

I am guessing if your temps get that high you are probably in a dry climate.  Maybe consider either an evaporative cooler (swamp cooler) that blows moist air into the home to cool the air by evaporation, or some sort of water feature inside to cool the air by evaporation.
https://www.newair.com/blogs/learn/what-are-evaporative-coolers

Trees.

Someone mentioned it before and there are other things you need to handle as well (like insulation). But the best time to plant a tree is twenty years ago, the second best is right now. Long term, trees planted along the southern perimeter (if you're in the northern hemisphere) will make a huge difference.

Trees not only provide shade, but they perform evapotranspiration (https://en.wikipedia.org/wiki/Evapotranspiration). Basically the heat energy from the sun is being used by the tree, not just being absorbed, like in the case of a roof.

Follow other people's advice, but get started on some large shade trees. Get them a sufficient distance away so as not to hurt your foundation, and play around with height and spacing so that at maturity they're doing exactly what you want.