I am planning the build of a large (3000sqft+), off-grid, single level, multi-family home in Belize. The home site is on the west side of a hilltop with excellent steady breezes from the east. After discovering the earthship concept a few years ago, I became fascinated by the passive cooling aspects of the design, and I want to incorporate cooling tubes which will pass under the peak of the hill and directly into the eastern wall of the home. The eastern wall will act as a retaining wall, and will be dug into the hill side, which means that most of the prevailing wind will pass over my house. So by placing the cooling tubes under the peak of the hill, I will not only be able to capture some of that natural breeze, but also cool it before it enters the house. My question is about the tubes themselves, this is a hot humid climate, what should I be after in regards to:
1) Number of tubes?
2) Diameter of tubes?
3) Material for the tubes?
4) Length of the tubes?
5) Depth of the tubes?
In order to cool a 3000sqft home, I a guessing that I will need quite a bit of capacity, but I also am concerned that it I get a single large tube (say 24" diameter), then there will not be sufficient surface-area inside the tube for proper cooling to occur. So I'm thinking multiple smaller tubes would be better, but what size & how many is optimal is not easy for me to figure out. So I'm calling on the experience & wisdom of the permies to help me figure it out, thank you.
The next questions would be, if I can come up with an idea that will have a very high likelihood of success...what do I do about windows in the home? Do I reduce the amount of windows (increasing the very highly insulated wall area) and rely on the tube(s) for cooling, or do I maximize windows to supplement the cooling tubes?
edit - BTW, winters are of ZERO concern here. The coldest temps here are mid to high 50s (F) and we can add layers to deal with that....I am ONLY concerned about cooling and potentially dehumidifying the air.
If you're dug into the hill, you can use geothermal cooling, dig pipes into the ground to use earth's stable temperature of 13-14 C. As for the breeze pipes, they should be smaller, to cool the air down as it passes through. Bigger pipes and windows would just ventilate the space, but the air temp would still be outside temp.
The thermal battery doesn't work that well in Belize.
Because the air temp and house temp is already pretty much the temp of the soil 10ft deep, even between winter and summer. (Overall there is at most a 7F difference).
What you want to control is the rate of evaporation aka humidity. So having a underground house at 82F vs the outside temp of 89F is great but the humidity will be at 100% which actually make it feel alot hotter than outside.
I highly recommend that you vent the bathroom (steamy shower) and the kitchen (boiling water).
Given that the house will feel relatively comfortable, with its earth/cave temp. I recommend getting a dehumidifier to reduce the humidity.
...."..which means that most of the prevailing wind will pass over my house. So by placing the cooling tubes under the peak of the hill, I will not only be able to capture some of that natural breeze, but also cool it before it enters the house.."...
I’ve been in and out of the construction industry for 50 years. I’ve worked in 7 or 8 countries, I’ve done stick built, adobe, rammed earth, concrete glass and steel, gut rehab. I’ve underpinned in Napa Valley , tunneled in Poland and helped build an earthship. I have never seen cooling tubes that worked as the builder/client/designer hoped. NEVER. I’ve seen them lined with fungi and over run with a rat colony. I’ve personally only ever met one person who said that they worked; he was the designer builder of his own house.
The questions you ask need data to answer them not opinion, not even mine.
This is your idea.. ..”..which means that most of the prevailing wind will pass over my house. So by placing the cooling tubes under the peak of the hill, I will not only be able to capture some of that natural breeze, but also cool it before it enters the house ..”..
About the only thing that can catch a breeze is a sail. If you want a breeze to pass through a tube you’ll need fans to catch it and direct through your tubes. You mentioned the breeze comes from the east, I think, well that cool Atlantic breeze will bring humidity and salt that might rust your car in the garage and damage any electronics you have in the house if, the breeze gets in.
You’ve got constant wind and equatorial sun. In that situation I personally would use a wind generator and photo voltaic panels to power one of the new generation DC powered mini split air conditioners. They run on 48v and only run as they receive power. You have daytime sun and perhaps night time breezes.. you might have AC 24/7 and dehumidification.
A few general comments:
About those EF blocks …. they are a vapour barrier, they will maintain a lot of humidity in your house.
You’re planning on a single storey house with a roof area of 280 square metres! You ought to look up how many KW of solarenergy that will soak up during the day and pass into the house structure at night. I think you’re planning a Steam Oven of a house and I suggest you seek out a tropical climate architect/engineer to guide your house design.
You’re asking for data but none exist.
I wish you well.
Michael Reynolds tropical designs do not really resemble his Taos earthships.
Tropics designs are pretty similar. High ceilings, lots of ventilation, highly insulated roof. Those traditional thatch roofs--they breathe, insulate, and create evaporative cooling--that needs to be emulated in whatever roof material you choose.
"You must be the change you want to see in the world." "First they ignore you, then they laugh at you, then they fight you, then you win." --Mahatma Gandhi
"Preach the Gospel always, and if necessary, use words." --Francis of Assisi.
"Family farms work when the whole family works the farm." -- Adam Klaus
I would suggest the installation of a "Safari" roof over your house.
They are another layer, insulated if need be that shades and creates an air space between the two roofs.
It will take 40deg C off the roof itself and vastly reduce the heat input as explained by Steven.
John Daley Bendigo, Australia
The Enemy of progress is the hope of a perfect plan