Jeremy Baker

The stick built house I’m in the hot desert was designed for somewhere else. It gets hot during the day and cold at night. It needs help. I’m tired from going in and out ten times a day struggling with the broken evaporative cooler that isn’t working correctly. I can’t get anything done because this thing and the heat takes most of my energy. And it’s using a lot of water. I’d like to plant vines but the they have to be protected from all the hungry animals that would devour them. That means fences and other protections from the wind which will whip up and destroy things. Everything feels like a big project because the house was not designed well from the outset. I think they were snowbirds who never intended to live here in Summer. And did not plan on much gardening.
 My current bandaid fix is to funnel the water from the leaking evaporative cooler to a few trees so the water is not wasted. And to run the cooler at night. That’s what I should have done last night but didn’t. I loath bandaid fixes. I’d prefer to fix this house permanently so it doesn’t need much cooling.  But for now I’m looking at sail shades on the west and east side which are great but need huge posts or the wind will take them to the next county. And vines that cover areas that the sail shades dont cover but it’s too late for vines this season. So much is about timing.. This is the goal for next spring. Build planters in winter and plant in spring. And fix the old evaporative cooler. If it was my house I’d do a rammed earth addition to add mass and much more insulation in the roof. I’d build a tower on the roof to suck warm air out and draw cool air in from tubes buried under the rammed earth addition. I’m frustrated after studying this stuff for 30 years to end up with another poorly designed stick and drywall house. Built for somewhere but I dont know where lolz. I see broken down houses out here. As if someone just gave up. I fear I might end up like that. Starting over is hard. Sigh.

S Benji. The numbers help place the design in perspective. I was hoping a body of water might have a lower average temperature due to night time to cool down and if it has a small surface area exposed to sunlight but is deep. The deep ponds I’ve experienced are cold in the deep part and only warm in the shallow areas. Also I was considering burying the loops under the pond liner and deeper than 10 feet but that might reduce conductivity.
Evaporative loss is a concern here in the sunny windy low humidity desert. A small but deep pond might help with that. Also a wind berm might help.

Pumping 10 gallons or higher per minute sounds like a lot! I’d prefer to keep it lower than that. But I’m concerned that the size and investment of the geothermal loops might just be too much.

The cooling season is also the monsoon season with a average of 15” precipitation. So I’m curious to see how a swale and roof catchment  works.

I’m considering building a Adobe walled room around the E, W, and South side of the house and growing food in a passively conditioned space. With a high mass floor this might temper the house temperatures passively thus reducing the need for active cooling. The performance depends largely on night time temperatures.

Also, a green wall and perhaps green roof as are design possibilities as  you suggested. Thanks.

Douglas Alpenstock wrote:

Jeremy Baker wrote:

Douglas Alpenstock wrote:Please describe the "pond pit." I assume this is a water-filled dugout? How much volume, and how deep?

Hi Douglas. The pond pit is a borrow pit we got the soil from to place our shop/barn on as this is floodplain. It is silty clay. Presently it’s 20’x50’, and slopes down like swimming pool to 7’ deep.  I calculated it at about only 50,000 gallons presently ...

Thanks Jeremy. I just wanted to make sure I understood the system design you were proposing -- the heating/cooling capacity does not come from piping in the trench that contacts soil, but from the mass of water in the pond.

What typical soil temperatures would you expect in your trench, summer and winter?

This geothermal is fun to design. I understand the heating/cooling capacity comes from the pond but the trench from the house to the pond will only be 30” deep so I do not want the chilled or heated water to be affected by the soil temperature as it goes for the house to the pond or the pond to the house. Also I’m not sure if the heat pump reverses the direction it’s pumping the water when it switches from heating to cooling. It’s different concepts than I’m used to. I’ll look for soil temperature maps. I’m told the soil gets very warm in Summer so I’m thinking of floating solar panels to shade the pond (and reduce evaporation) and make it deep like at least 10 feet. Fun design challenges.

S Bengi wrote:ERV unlike HRV 100% helps in the summer AC season. I recommend getting one.

Yes, insulation and dealing with heat source will be a major help. Have you thought about a green roof. You could plant all your veggies up there, the plants and water will keep your house cool, and it will be a cool garden spot to hangout in. You probably only need  3inch of growing media (think hydropnic), with the water recirclulating so it uses less water and it cools the roof and it produces a harvest.  

Whats your average winter temp for me it is 30F for the coolest month (Jan) so if its even warmer for you, It's possible that just winter solar gains is all you need.

I’m inspired by these ideas to make this house habitable without being a big energy liability and food desert. We are currently still burning propane for heat. The average winter temperature is about 45 degrees. It’s frosty then sunny and warm to about 60 most winter days. So passive solar gain could work well here. I’m now inspired to make this a envelope house and build Adobe walls around the E,, W, and South with solariums to gain warmth. A hybrid Earthship sort of house. It would probably never perform as well as a Earthship but we are in mild southern New Mexico not cold northern New Mexico.

Douglas Alpenstock wrote:Please describe the "pond pit." I assume this is a water-filled dugout? How much volume, and how deep?

Hi Douglas. The pond pit is a borrow pit we got the soil from to place our shop/barn on as this is floodplain. It is silty clay. Presently it’s 20’x50’, and slopes down like swimming pool to 7’ deep.  I calculated it at about only 50,000 gallons presently but I might dig it out further. I was trying to stack functions by using the borrow pit for something. Also I wanted to see what the soil horizons are here. I’m considering making Adobe blocks and could use more of the soil for that. This would make the pit bigger. I was also having fun with the thought of a natural swimming pond. The edges of the pit are excavated  about 20” deep X 7 feet wide for gravel as filtration medium. Also as terraces to grow aquatic plants on sides of the pond One major issue is it will not seal without pond liner because the steep sides would not hold bentonite clay. If we bevel out the sides then bentonite or glaying might work.

I’ve had other fun ideas such as floating solar panels. Floating plants, a floating cabin, etc. Ponds and water can be fun.

I’ll add it’s currently completely dry presently as are all the cattle pits here that do not have water pumped to them. I’m channeling a swale to the pit and the roof runoff. I’m curious to see what it does during the monsoon. Im in the observation phase of the design. I’m going to fence it off to keep the cows from trashing it when it does have water. Our perimeter fence might get breached lol. Thanks for asking, what are you thinking ?

S Bengi wrote:ERV unlike HRV 100% helps in the summer AC season. I recommend getting one.

Yes, insulation and dealing with heat source will be a major help. Have you thought about a green roof. You could plant all your veggies up there, the plants and water will keep your house cool, and it will be a cool garden spot to hangout in. You probably only need  3inch of growing media (think hydropnic), with the water recirclulating so it uses less water and it cools the roof and it produces a harvest.  

I wonder if a green roof would work on this house. I’ve grown succulents on a small shed roof before. But I didn’t care about the resale value of the shed. I thought about building a shade structure around the south and west side of the house. It’s blazing hot there and the walls heat up. And misting but dont like using the extra water.
 Ive read your posts going way back in years. Thanks for all the positive input. I’ll consider these ideas.

S Bengi wrote:Yes HDPE is the way to go, I wasn't too sure what type of polypipe you were thinking of using.

I also think that you can get away with a 2ton system if your space is well insulation and you work on your sources of heat(baking/cooking/shower/etc). SO all you would have to do is scale all the number I gave you down by 50%.

ERV = Energy Recovery Ventilation, it basically send cool air outside and pull hot air into the house for ventilation, but will they are passing each other, they reach equal temp and so not all of your coolth or warmth is lost. You can throw it in the bathroom so that it is always sending bathroom air outside at say 40cfm, and then dump the filtered outdoor air in a shared space say the hallway/livingroom or the air handler. https://www.supplyhouse.com/Fantech-FIT70E-SE-Series-Energy-Recovery-Ventilator-4-Side-Ports-up-to-1200-Sq-Ft

If the house needs more than 2 tons cooling I’m moving ahah. The concept of a sand battery is a fun idea. Imagine being able to store much of the heat pumped out of the house all summer then reuse that heat in the winter. Of course it won’t be 100% efficient so would need some energy input.

I remember now. Energy recovery ventilator. Well, the heating season is so short I’m not sure it’s worth it. And I’m not sure the ERV helps during the cooling season which is the big load. I usually am forced to go North like bird but decided to get serious and build a system to cool the house. I may paint the roof white and line the attic with silver foil and all that stuff.

We don’t cook a whole lot. But it was 105 degrees here for 45 days straight last Summer. What’s a ERV?

Thanks S Benji.
I’m pretty sure we can get by with 2-3 ton GHP but will check that. House is only 1400 sq ft and well insulated. I may combine the geothermal heat pump cooling with a evaporative cooler as they are cheap. I’m going to take a screen shot of the numbers you posted and go over it. Why do you suggest PVC? I was under the impression that poly pipe HDPE is commonly used for GHP.