Living offgrid with small solar system(s)

[splitlid]

^but what about hamsters in wheels?

I reckon 25 hamsters on separate wheels should generate enough power to run the pump that will feed the sprinklers to cool the roof.

imagine what an army of hamster could do.

Take over the world.same as we do every night PInky.

[George Harmony]

Why do you want to stop this thread. @naam said b4 there are no alternatives. Now you just said water immidiately cools under a zinc metal roof.

So if a model of my house is like attached pict and there is no attic it means i can cool my room(s) if i have zinc metal roof.

Im just looking for alternatives to achieve an acceptable inside temp.

[bankruatsteve]

Yeah. i think so. Not sure you will notice it much though.

[Muhendis]

cooling any medium with a cooler medium is neither fiction nor reinvention of the wheel

And it thoroughly pee's off many people who see it as a waste of water.

extremely efficient however is misting the condenser units of the aircons with water which can increase cooling capacity easily to 50% and more depending on water/ambient temp delta t.

Don't they do that already for production of legionella?

[Muhendis]

Why do you want to stop this thread. @naam said b4 there are no alternatives. Now you just said water immidiately cools under a zinc metal roof.

So if a model of my house is like attached pict and there is no attic it means i can cool my room(s) if i have zinc metal roof.

Im just looking for alternatives to achieve an acceptable inside temp.

The name of the game is not allowing things to get hot in the first place. Arrange to keep the sun off the roof. A secondary light weight roof would be a good way to go. The secondary roof would have an air gap between it and the primary roof which would allow air to flow between the two. The air gap would need to be big enough to make the transmitted radiant heat from the secondary negligible.

If the two roofs have a carefully controlled air gap they would make a brilliant supercapacitor too

[Naam]

cooling any medium with a cooler medium is neither fiction nor reinvention of the wheel

And it thoroughly pee's off many people who see it as a waste of water.

extremely efficient however is misting the condenser units of the aircons with water which can increase cooling capacity easily to 50% and more depending on water/ambient temp delta t.

Don't they do that already for production of legionella?

condensers are outside, mist evaporates on hot condensers, legionella can breed only in water.

you are mixing up compressor/condenser units with cooling towers which are ideal places for any bacteria breeding.

.................

[Naam]

The name of the game is not allowing things to get hot in the first place. Arrange to keep the sun off the roof. A secondary light weight roof would be a good way to go. The secondary roof would have an air gap between it and the primary roof which would allow air to flow between the two. The air gap would need to be big enough to make the transmitted radiant heat from the secondary negligible.

If the two roofs have a carefully controlled air gap they would make a brilliant supercapacitor too

[Naam]

Yeah. i think so. Not sure you will notice it much though.

the immediate cooling effect is equivalent to the fan effect of a baby's fart in Bangkok's main train station.

[George Harmony]

@naam, if you have time pls read this and give your usual "german style" opinion.

http://www.solaripedia.com/13/39/405/az_rooftop_sprinkler.html

[bankruatsteve]

Yeah. i think so. Not sure you will notice it much though.

the immediate cooling effect is equivalent to the fan effect of a baby's fart in Bangkok's main train station.

For example... we run water over the roof of our chicken house when it's HOT and it immediately feels cooler underneath. It doesn't last much longer than running the water but it does provide some relief. I think more than a baby fart.

I've also been at some restaurants that run a constant trickle of water over their metal roof (covering a non-enclosed space) and that does seem to help deflect what would otherwise be radiant heat to the underneath.

[Muhendis]

Naam....What you seem to be saying is that by spraying water mist onto the (external) condenser heat exchanger, the heat therein is more effectively removed. Perhaps the condensed water vapour from inside the room could be used for this although it may not be sufficient to achieve maximum improvement.

[Naam]

Yeah. i think so. Not sure you will notice it much though.

the immediate cooling effect is equivalent to the fan effect of a baby's fart in Bangkok's main train station.

For example... we run water over the roof of our chicken house when it's HOT and it immediately feels cooler underneath. It doesn't last much longer than running the water but it does provide some relief. I think more than a baby fart.

I've also been at some restaurants that run a constant trickle of water over their metal roof (covering a non-enclosed space) and that does seem to help deflect what would otherwise be radiant heat to the underneath.

my comments have to be taken in context with "cooling" a home which does not have pressured water supply and extremely limited energy sources.

correct is of course that a constant water spray on any surface reduces material heat and therefore radiation.

but "reducing heat radiation" does not equal "immediate cooling effect" (my reference "baby fart").

[Naam]

Naam....What you seem to be saying is that by spraying water mist onto the (external) condenser heat exchanger, the heat therein is more effectively removed. Perhaps the condensed water vapour from inside the room could be used for this although it may not be sufficient to achieve maximum improvement.

it's not only the initial delta t water/ambient that cools the fins but the additional cooling effect of water evaporating.

using very cold condensate from the inside units is a double edged sword because of its corrosiveness (hungry water). your assumption that the quantity is insufficient is correct.

[Naam]

@naam, if you have time pls read this and give your usual "german style" opinion.

http://www.solaripedia.com/13/39/405/az_rooftop_sprinkler.html

sorry George but that's another wet dream of a wannabe inventor to which my baby fart comment applies except if the water sprayed on the roof is icecold and sufficient in quantity. does not apply in your case.

Edited May 11, 2016 by Naam

[George Harmony]

Again stubborn George. In my case water is no problem at all. Also groundwater. Sprinkling a roof for couple of hours thus no problem with my tiny pumps hehehe....see the thai vid posted by me for @gary before, page 28.

If its working for a chicken shed why not for my tiny house?? Give me a good reason. Ofcourse it wont work like an aircon but if inside it will be cooler, why not give it a try.

Attached pict screenprint sprinkler system thai vid page 28.

[George Harmony]

Let me put it this way:

If i dont sprinkle it will be hotter inside.....right or not??

[IMHO]

^but what about hamsters in wheels?

I reckon 25 hamsters on separate wheels should generate enough power to run the pump that will feed the sprinklers to cool the roof.

imagine what an army of hamster could do.

Take over the world.same as we do every night PInky.

I still think a solar heat powered stirling engine make more sense

[IMHO]

Again stubborn George. In my case water is no problem at all. Also groundwater. Sprinkling a roof for couple of hours thus no problem with my tiny pumps hehehe....see the thai vid posted by me for @gary before, page 28.

If its working for a chicken shed why not for my tiny house?? Give me a good reason. Ofcourse it wont work like an aircon but if inside it will be cooler, why not give it a try.

Attached pict screenprint sprinkler system thai vid page 28.

If using ground water, just bear in mind that your roof might not look very pretty for long

[IMHO]

Let me put it this way:

If i dont sprinkle it will be hotter inside.....right or not??

It should cool down your attic, yes. How much effect it has on the rooms below solely depends on how good your insulation is.

I can say that in my houses, it wouldn't do much - we get maybe only 2-3c of heat gain through the ceilings each day, and that's all happened by mid-afternoon anyway. We use ventilated soffits all the way around our house though, so as soon as there's any breeze, the attic is getting cooled naturally, and completely free.

[Naam]

If its working for a chicken shed why not for my tiny house?? Give me a good reason.

give me good definition of "tiny house" and section sketch of structure.

[George Harmony]

I found a model roof/house/cabin the same as mine. House is 5*9m plus attached to the right behind 3*3m. There is no attic. Roof frame is from 4mm thick hollow steel.

This pict is from somewhere on internet and my walls are brickswall.

Above all windows and doors there are floating roofs(canopy).

Circulation of air by passive cooling is i think ok. Plus fans is with such a roof also ok till now. Only when its not raining and outside its very hot inside can reach 30c. Evening i dont have any problem, average 26-27c and sleeping with the breeze of my usb fan fantastic hehehehe

[George Harmony]

Still a mess, still not ready, some picts inside

[George Harmony]

If using ground water, just bear in mind that your roof might not look very pretty for long

as posted b4 i use a pvc-pipe-well. I filter it with 3 filters before entering my watertank. The pipe enters my tank is at the same level as the highest level of my roof. In one hour my tank is full again and the remaining peak hours i can with simple adjustment sprinkle my roof with that filtered (colder) water.

Ive read somewhere that a guy in aus circulate water from a big barrel to/trhough his roof at night time. Cause of the night radiation he gets cold water early in the morning in his barrel which he uses for his evaporate coolers. Also an idea to get cold(er) water. Tiny pumps do not draw a lot.

[Jing Joe]

Why do you want to stop this thread. @naam said b4 there are no alternatives. Now you just said water immidiately cools under a zinc metal roof.

The name of the game is not allowing things to get hot in the first place. Arrange to keep the sun off the roof. A secondary light weight roof would be a good way to go. The secondary roof would have an air gap between it and the primary roof which would allow air to flow between the two. The air gap would need to be big enough to make the transmitted radiant heat from the secondary negligible.

Hi GEORGE Just so happens I wanted to have less rain noise on the tin roof over one big bedroom so I used heavy grade, U/V rated shade cloth with about 100mm gap over that bedroom.

It worked so well and the noise reduction (as measured) is same as some sound deadening sheet material 12mm in another bedroom over the 50mm polystyrene heat insulating ceiling.

No need here to increase the insulation to stop the sun heating the house, just needed "raindrop disintegration". Polystyrene is useless against noise.

Used vertical 125mm long spacers of black poly pipe 25mm dia, with split bottom ends bent and secured with one each of the existing roofing screws. Over the top of the then 100mm poly pipe posts is a tight wire system to hold the mesh up.Lengthwise and then a few diagonals. I drilled holes very near top of posts for the wire to pass through to secure. The ends of these were also secured by existing roofing screws..

Then the mesh on top was stretched tight with those black butterfly clips for the purpose,latching on the edges and again with suitable short lengths of wire were secured to existing roof screws. They squeeze together with mult-igrips. The gauge of fencing wire was easily kinked with pliers as many times as needed to tighten the wires.

George, If this wasn't enough cooling effect to keep the sun off your roof, one could spray water and see how evaporation would go. Not an expensive project and a very simple and light way to shade the roof. Obviously your heat input to the house from the roof causes you grief. Mine doesnt but used to before the 50mm polystyrene sheets.

[George Harmony]

Thanks for the tips @jingjoe. Yeah, indeed a metal roof, although mine is the tickest i can get here, its very noisy when its raining hard. Someone said b4 if i wanted to store rain water later use metal roof. Thats why i did it. Ill try to follow your tips

[Naam]

metal roof

when we lived in the wilderness of the African bush the house had a mirror-polished aluminium roof. no attic insulation, ceiling some sort of thick cardbord 25mm thickness, attic naturally ventilated, aircon demand absolute minimum!

and when it rained heavily we liked it

[George Harmony]

I talked about metal. But i think mine is zinc aluminium. Like this.

Aircon demand minimum @naam. Why did you not put such a roof in your current house???

[George Harmony]

Yeah. i think so. Not sure you will notice it much though.

the immediate cooling effect is equivalent to the fan effect of a baby's fart in Bangkok's main train station.

For example... we run water over the roof of our chicken house when it's HOT and it immediately feels cooler underneath. It doesn't last much longer than running the water but it does provide some relief. I think more than a baby fart.

I've also been at some restaurants that run a constant trickle of water over their metal roof (covering a non-enclosed space) and that does seem to help deflect what would otherwise be radiant heat to the underneath.

This morning with some rest wood ive made a temporarely floating roof with zinc aluminium. Its now rather hot and perhaps you can fry an egg on it. Then i spray ground water and it cools immediately. This a room just build not plastered yet. I think the heat in de rooms comes mainly by/through the roof. Soon i will install a sprinkler system on the roof.

[George Harmony]

If its working for a chicken shed why not for my tiny house?? Give me a good reason.

give me good definition of "tiny house" and section sketch of structure.

Ive answered. So, whats your opinion.

Here is a case study:

Example:

A 100,000 sq. ft manufacturing facility has a metal roof with 2-in. of fiberglass insulation, 325 tons of mechanical cooling, and an inside design temperature of 78 F. The fiberglass has a U-value of 0.14. Using ASHRAE criteria, CLTD is determined to be 71.4 F.

q = (0.14)(100,000)(71.4) = 999,600 Btu/hr heat load.

Dividing this by 12,000 Btu/hr (one ton of air-conditioning) gives a dry solar roof heat load of 83.3 tons. That is over 25% of the buildings total heat load.

It is understood that a roof gets very hot in the summer and creates a tremendous amount of heat gain in a building, but this problem is too often accepted as a fact of life. There is a solution.

To reduce the load on air conditioning systems, a growing number of companies are cooling the building from the top down using water. Evaporation is a natural way of cooling.

When one gallon of water evaporates, it absorbs about 8,000 Btu's. Evaporative roof cooling is based on this fundamental principle.

Roof cooling began over 60 years ago. Ponding, rather than evaporation, was the original concept. Although it had some drawbacks, the overall results were very satisfactory for this cooling concept. Ponding was good, but would not work on all roofs, and had too many negative effects on the roof. Engineers worked to change the concept of roof cooling from a ponding to an evaporative technique.

If well water is available, the operating cost for a roof cooling system is next to zero.

http://m.plantengineering.com/index.php?id=9539&tx_ttnews%5Btt_news%5D=32901&cHash=abc58f7252585592c396e1f8006ecb76 Edited May 12, 2016 by George Harmony

[Naam]

I talked about metal. But i think mine is zinc aluminium. Like this.

Aircon demand minimum @naam. Why did you not put such a roof in your current house???

as per your suggestion i will use tomorrow a time machine (powered by a 7ah battery) to go back to october 2005 (see picture) and change the roof tiles to zinc aluminium.

if my wife asks why i will tell her "H@rmonic Indo-George told us so!"