Things to aid cooling / avoid heat gain

[gtojohn]

Low cost radiant barrier, 250 sqft for $8
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[AC_Hacker]

Here's a technique that seldom gets used, intermittent spraying of water directly on the roof.

The cooling due to water spray is only part of the effect, but the real heat remover is the evaporation of the water. Intermittent spraying rather than continuous will give you the most bang for the buck.

Works great on a comp roof, not so good on a metal roof, because of run-off.

A misting hose is perfect, and watering timers with the ability to set intervals work wonders.

My gal used to suffer working in a country convenience store with a shed roof. Not much insulation, the owner was too cheap for A/C, so just huge fans.

She tried the idea and it dropped the temp inside the store 10 degrees F.

Happy gal.

Good idea.

-AC

[cwwilson721]

Some of us don't have/cannot get into our attic spaces, like myself: I live in a 16'x80' Metal sided mobile home, with a metal roof.

Our insulation is EXCELLENT, however. In winter, I can keep the inside of the house at a livable 54F with just 1 1500w space heater. So I know the insulation is fine...

However, I live in Alabama. HOT. Humid. Sunny. And, the "long" wall of the house is south facing. With metal siding. That combination makes for a VERY hot house in the summer, with EVERY stud in the 80' south wall a RADIATOR.

I mitigated that somewhat with a porch/deck roof that covers the main living/dining/kitchen space, and painting the roof with Arctic Cool White. But I was STILL having to run the A/C at full blast 16hours a day to get it even halfway comfortable in there (could still reach 90F).

So, I put a small (5000BTU) window unit in my living room, on the south side (shaded by the porch roof), and raised the thermostat of the central A/C 5-6 degrees.

It is now: MUCH more comfortable, lower humidity, the extra "cool" is on the hot wall, reducing heat gained into the house, and since my central unit runs <8 hours/day now (About noon-ish until sunset), that reduction alone saves me over $70/month in electricity.

Next step: Thermal break the siding from the wall studs, add radiant barrier behind the siding, and use a wood product for most of the siding on the south wall. I have solar thermal air and water heat for winter (6 distributed indoor "space heaters"), that use hot air during the sunny days, and the stored hot water for night time use. An added benefit is the 6 outside solar hot air collectors (16"x8') provide some 'break' from the heat gain. I expect DRASTICALLY reduced electric bills in the winter. 150w total with all 6 units "running", with water heat and fans, putting out ~12KBTU/hr max. Compare that to the electric furnace and DHW...

For this season, I'm happy tho. I'm running a 515w window unit to take care of most of the humidity issues, and the bulk of the house cooling. The central A/C now only comes on when the heat is too much for it.

[Daox]

Smart upgrades cwwilson721. Thanks for sharing.

[cwwilson721]

Originally Posted by AC_Hacker

Here's a technique that seldom gets used, intermittent spraying of water directly on the roof.

The cooling due to water spray is only part of the effect, but the real heat remover is the evaporation of the water. Intermittent spraying rather than continuous will give you the most bang for the buck.

Works great on a comp roof, not so good on a metal roof, because of run-off.

A misting hose is perfect, and watering timers with the ability to set intervals work wonders.

My gal used to suffer working in a country convenience store with a shed roof. Not much insulation, the owner was too cheap for A/C, so just huge fans.

She tried the idea and it dropped the temp inside the store 10 degrees F.

Happy gal.

Good idea.

-AC

This technique works WONDERFUL in low humidity areas, as do swamp coolers.

But, unfortunately, is a waste of water in my area. Humidity is WAY too high for either of those solutions to work. A swamp cooler would just dump humidity in the air here, with no cooling, and the water on the roof just makes the ground wet.

But, if in lower-humidity areas, both are excellent cooling solutions. IF you can use water like that (some areas are severely restricted in water use, or you do not have the water resources available, such as rain barrels/etc).

[AC_Hacker]

Originally Posted by cwwilson721

However, I live in Alabama. HOT. Humid. Sunny. And, the "long" wall of the house is south facing. With metal siding. That combination makes for a VERY hot house in the summer, with EVERY stud in the 80' south wall a RADIATOR.

Your trailer will be absorbing energy from all sides but, like you said, especially the south side.

I have had good luck using outside shade material, in addition to strategically located food-producing vegetation, that stops, or even better, utilizes solar energy before it reaches the house.

Below is the southeast side with a white exterior shade, but even better, new plantings put in just this year. The new "Fig" went in just this year, and has already produced two samples of coming attractions, as well as having set a second crop. "C-1" and "C-2" are newly-planted currants almost lost amidst the weeds (Bad AC, Bad gardener!!). "S" is a bed of strawberries (4 varieties), and "G" os a Korean Gobi bush that bears a very curious berry about the size of a grape. Also off to the left side, "T" is a patch of tomatoes and tomatillos. My strategy is to use a Permaculture idea and plant in layers, so the Fig will be highest (and will male the white shade unnecessary). Then the currants and Gobi will be the understory, and the strawberries will be the ground cover.

Here is the south side of my house, and you see the bamboo shade, and also delicious green seedless grapes growing along the top of the porch trim. At the bottom of the bamboo shade is an espaliade apple tree, shaped flat, and bearing six different wonderful apple varieties grafted to it.

\
I'm sure your deck roof helps... by the way, if you have some kind of double deck roof with air flow between even better.


Here's a shot of the west side of the house...

Here along the west side, I have planted a fig tree, which gives me figs and shade, and there is a hazelnut tree to the left of the fig tree that bears nuts and produces shade. Over the back of the house is a Bartlett pear tree, so delicious in the late summer!

I don't know if you own the property your trailer is on, but two or three 5 gallon buckets filled with dirt and planted with hops in the spring, would shade the sides and top of your trailer nicely.

Kudzu would work too, but the neighbors might rebel.

-AC

[cwwilson721]

Kudzu? Don't have to plant it. It just shows up around here...

I had a stand of trees in front of my house, but sold them for pulp wood (Paid for the house). Haven't replanted them because the energy savings in solar heat in the winter and DHW all year offsets the reduction in cooling costs in the summer.

Cannot afford a new roof right now, so that's out. And if I DO put one on, it will be a corrugated aluminum, with a 8' overhang along the entire south side, and will utilize PEX tubing for solar hot water (also in the peak ridge vent), 2" of insulation, and a 2" airspace underneath above the existing roof. Will have (on south roof) approx 1280 sqft of solar hot water collection, which, in my area, should give me ~240Kbtus/hr in winter. Even if it's only half, that's still 120K BTUs/hr or 720KBtu's for the day...Yeah. I only need 288k/day for the coldest day for the house heating needs, of which 72KBTUs are taken care of by the existing solar air heat. That leaves 216k for the house, and THAT leaves ~504K BTUs of "excess" capacity...So, I could almost heat the whole freakin neighborhood. Free. Except costs for pumps/controllers. (The heat output is already being done via a large collector I have already built, but it's HUGE, and would prefer to "build it into the roof")

My last winters energy costs were approx 120/mon for electric furnace and DHW. That will be almost 0 for the 4 month "heating season". So $480/yr "extra" (at least. Still making hot water for DHW). Putting up trees for shade will possibly reduce my current cooling cost from ~120/month to 80/mo, a saving of $40/mo for the 8 month "a/c season", so at best, it's a wash. Put up trees, my winter and DHW will go up. I save more $ and costs without the shade...

It all comes to balance. I got the savings in heat, and can't really trade that for cool...So, I have to do what I've done, and planning for

[AC_Hacker]

Originally Posted by cwwilson721

Putting up trees for shade will possibly reduce my current cooling cost from ~120/month to 80/mo, a saving of $40/mo for the 8 month "a/c season", so at best, it's a wash. Put up trees, my winter and DHW will go up. I save more $ and costs without the shade...

It all comes to balance. I got the savings in heat, and can't really trade that for cool...So, I have to do what I've done, and planning for

I'm not sure what kind of shade trees you have in there in Alabama, but where I live there are deciduous trees that have leaves during the summer (when you want the shade) and drop their leaves in the winter (when you want the solar gain).

Fruit trees are an example of deciduous trees.

-AC

[cwwilson721]

Yes. But the costs (of the trees/etc, and the reduction for DHW don't really add up (for me).

But, shade is a GREAT way to reduce heat gain. I just plan on doing it "whole hog" via the 80x8 "porch roof". Other benefits for me are a carport and a place to build my "solar shed" under the overhang. I'll lose the hot-air collectors I currently am using due to the shading, but will have a possibility of using a "fascia mounted" combo tube-type hot-air collector and rain gutter.

I'm just pointing out that there are more considerations, for me, than just shading via trees/etc. The entire house and systems have to be considered.

[gtojohn]

You could use an a/c condensate pump to pump your a/c drain water onto the roof. It would run as your a/c does. Its humid here too, they'll put out 5 gallons or more a day. The pump reservoir fills up 1 to 2 quarts before they drain. They push 17-21' of head, enough to squirts pretty hard. It wouldn't be too hard to make a little sprinkler head to cover more area. I understand how the swamp coolers don't work but spraying cold water on a 100F+ roof should remove some heat through conduction and I bet some through evaporation. You could capture the run off in the gutters for a 2nd use. For some quick and removable shade those triangle canopies are cheap and easy to install.