Green Building Forum - AGS inter-seasonal storage project - Planning Permission awaited

AGS inter-seasonal storage project - Planning Permission awaited

Terry — Wed, 21 May 2008 21:47:23 +0100

Benj
I dont think the problem is in specifing a super insulated house as there are lots of examples around and more coming all the time. ie the detailing required is understood and documented.
The problem is converting the recommendations into actual bricks and mortar (or timber frame ) - particularly in the UK with the current level of education and the dominant mindset in the building industry.
It comes down to quality control of the detailing.

AGS inter-seasonal storage project - Planning Permission awaited

Jeff Norton (NZ) — Wed, 21 May 2008 22:05:52 +0100

IMO the point to AGS is that you do not need to go to great lengths in super insulation, air tightness details, large arrays of solar panels or specialist tradesman! it is about combining or balancing the most cost effective (money & energy) aspects of each element.

Using standard building practices with a little extra thought in the design (& simulation) stage should result in maximum benefit for minimum input, that is sustainable and market ready on a large scale.

AGS inter-seasonal storage project - Planning Permission awaited

fostertom — Wed, 21 May 2008 22:56:35 +0100

Nicely clarified, Jeff. With your own private non-fossil store of energy, you don't need to do all the saving and conserving stuff 100% perfectly. There's no particular limit to how much you can store, compared to your house's heat demand - just a question of how much collector area (of various kinds, incl. your windows) you have space for, and/or can afford. At the logical extreme, you could decide to spend all your money on collecting and storing, and none on insulation etc.! Meanwhile

Posted By: Terrythe detailing required is understood and documented ..... It comes down to quality control of the detailing.

and that will improve, given some little time.

AGS inter-seasonal storage project - Planning Permission awaited

Benj — Thu, 22 May 2008 05:36:17 +0100

Thanks Terry,
Your point illustrates exactly why I am building my own house and doing most of the work myself.
After reading Sue Roaf's Ecohouse book a couple of years ago, I dared to raise a couple of issues (such as nylon wall ties) with our then architect only to be told not to be so silly and to be happy with the generic box he was designing.
If some architects are so stuck in the mud, you can hardly expect builders to be worried about the finer points of keeping cavities clean and properly installing insulation.

AGS inter-seasonal storage project - Planning Permission awaited

stephendv — Thu, 22 May 2008 06:58:43 +0100

Benj, on the topic of wall ties: Are they the metal rods used to link the interior and exterior walls? Our new build will be thin masonry inside + insulation + stone on the outside and the architect has mentioned that we'll need to use metal rods to link the interior and exterior walls through the insulation. He also balked at the idea that these ties would contribute to the thermal bridging effect. What are they alternatives?

AGS inter-seasonal storage project - Planning Permission awaited

Benj — Thu, 22 May 2008 07:14:00 +0100

Stephendv

From what I can gather, metal rods most certainly will contribute to thermal bridging, especially the larger ones needed for wide cavities.
There are alternatives. Im looking into reinforced Basalt wall ties right now. They are called the Teplo tie and distributed by Magmatech over here.

AGS inter-seasonal storage project - Planning Permission awaited

ludite — Thu, 22 May 2008 08:12:04 +0100

stephendv. I don't believe it!! Thanks for that last link! I was thinking about sand as a thermal store myself and have just had a look at what they have to say. Amazing!

AGS inter-seasonal storage project - Planning Permission awaited

Benj — Thu, 22 May 2008 09:34:23 +0100

I think "collector area" is the key here.
In order to do away with insulation / airtightness etc you will be talking about a LOT of collector area which will have to be south facing (in the UK)
if something sounds too good to be true, it usually is ......

AGS inter-seasonal storage project - Planning Permission awaited

Mike George — Thu, 22 May 2008 10:42:23 +0100

I don't think anyone is suggesting that insulation and air tightness is done away with - I certainly am not.

AGS inter-seasonal storage project - Planning Permission awaited

fostertom — Thu, 22 May 2008 11:05:14 +0100

And I said "at the logical extreme", just to illustrate the point that truly inter-seasonal storage (which the sand idea is not) allows you to relax a bit about extreme, perfect insulation and airtightness, which Passivhaus etc relies upon.

AGS inter-seasonal storage project - Planning Permission awaited

Benj — Thu, 22 May 2008 11:09:15 +0100

I think Fostertom and Jeff Norton have implied that this technology will give us boundless amounts of almost free heat - so that we dont have to worry about insulation etc.
My argument is about the amount of collector area that would be required to make this viable - compare it to a patch of woodland - quite an efficient method of solar energy storage, yet no one is suggesting you could heat a house for a season on the wood produced from just a few square metres of trees ?

All im suggesting is the cost / benefit is not going to make this method useful to more than a handful of dwellings.

AGS inter-seasonal storage project - Planning Permission awaited

Mike George — Thu, 22 May 2008 11:13:47 +0100

Posted By: BenjMy argument is about the amount of collector area that would be required to make this viable

This requires Dynamic Thermal Simulation to quantify. It remains to be seen at present how big the thermal store needs to be

Posted By: BenjAll im suggesting is the cost / benefit is not going to make this method useful to more than a handful of dwellings.

We shall see - if we don't try new things - how will we ever progress

AGS inter-seasonal storage project - Planning Permission awaited

joe.e — Thu, 22 May 2008 11:22:10 +0100

Posted By: BenjI think Fostertom and Jeff Norton have implied that this technology will give us boundless amounts of almost free heat - so that we dont have to worry about insulation etc.
My argument is about the amount of collector area that would be required to make this viable - compare it to a patch of woodland - quite an efficient method of solar energy storage, yet no one is suggesting you could heat a house for a season on the wood produced from just a few square metres of trees ?

All im suggesting is the cost / benefit is not going to make this method useful to more than a handful of dwellings.

I was under the impression that trees actually didn't store all that much of the available energy from sunlight - 1% is the figure that sticks in my mind. What are the proper relative figures for woodland and the relevant means of collection discussed here?
I took the proposal to relate, in reality, to a very well insulated, very airtight house, and that the point was to take away the need for the extreme, expensive attention to detail needed for a completely passive house. It also doesn't sound like an inherently expensive system on the face of it - it's all straightforward, existing technology, just used a bit differently. So the cost/benefit ratio might be reasonable, viewed in the context of the potential savings in construction costs, especially given that some of the components might well get installed anyway.

AGS inter-seasonal storage project - Planning Permission awaited

Benj — Thu, 22 May 2008 11:49:26 +0100

Damn ! Ive just planted 4000 of them - I should have put something else in the ground!!

Sorry for being pedantic, but whats the difference between a "very well insulated, very airtight house" and a passive house.

AGS inter-seasonal storage project - Planning Permission awaited

stephendv — Thu, 22 May 2008 13:07:20 +0100

Posted By: BenjSorry for being pedantic, but whats the difference between a "very well insulated, very airtight house" and a passive house.

The german passivhaus standard quantifies exactly what the lower limit of "very" is.

AGS inter-seasonal storage project - Planning Permission awaited

chuckey — Thu, 22 May 2008 20:13:39 +0100

Fostertom, what caused me to say this is that I live in a house with 24" rock and rubble walls, so a lot of material here. When the sun shines the walls get hot on the outside and some of this heat is conducted into the room, a lot of heat is also conducted into the ground. When the sun goes in, the heat in the ground is then conducted up the walls and into space. So the effectiveness of using walls as a thermal store is the ratio of the time its getting pumped up with heat and the time the walls are pumping out heat. Idealy the interseasonal store should be totaly insulated so you can heat your rocks up to 90 deg C and regulate the heat output so the house only gets 20 deg C. For an existing house this is not really practical. Or at least very expensive. So I was thnking of getting the best bang for my bucks!
On the subject of the copper pipe and the insulation around the inner pipe, I feel that as this is the sole or perhaps one of two pipes getting the heat in and out of the ground, that its thermal efficiency should be good. With GSHP systems they use 10m of 22mm pipe per kW output. Another point brought up which I have thought about but not mentioned. Once the main pipe in installed a cutter is put on it to cut a 8" diam hole concentric with the pipe and say, 3 m deep. The cutter is withdrawn and insulation is then slipped over the main pipe. This is to minimise the heat input into the ground too close to the surface and its subsequent loss. No doubt an engineer would rebuild this as a 4" copper tube say 4 m long terminating in two plastic pipes sitting in a 4" diam rigid plastic pipe with insulation around them. So the pipe has only the copper heat exchanger bit in its active area.
As clear as mud?
Frank

AGS inter-seasonal storage project - Planning Permission awaited

David Olivier — Wed, 28 May 2008 18:20:39 +0100

To effectively store solar heat seasonally, I'd do as the Danes are doing in Marstal and other towns and build 10,000 m3 to 100,000 m3 insulated holes in the ground, filled with water. So far, nothing is very much cheaper. Stores this size also have a sufficiently low surface/volume ratio to hold heat well from summer to winter. Of course, one needs district heating to distribute the heat to buildings, but 65% of Denmark has district heating and it's still growing.

If you do the calculations, the volume of earth below a building needed to store say 5,000 kWh of heat at a 5K temp. difference is fairly large; i.e., above 2,000 m3.

David.

AGS inter-seasonal storage project - Planning Permission awaited

howdytom — Thu, 29 May 2008 10:13:40 +0100

I like your idea's frank,
but where do you source 4" copper pipe and at what cost ? the food industry uses 4" stainless steel pipe and its available second hand ! not as good a conductor but does that matter ?.
tom

AGS inter-seasonal storage project - Planning Permission awaited

fostertom — Thu, 29 May 2008 10:55:39 +0100

Posted By: David Olivier10,000 m3 to 100,000 m3 insulated holes in the ground

Why insulate? Not necessary, very costly, ineffective.

AGS inter-seasonal storage project - Planning Permission awaited

djh — Thu, 29 May 2008 22:03:38 +0100

Hi all, My first post here, so be kind :)

I'm very interested in inter-seasonal storage, as a result of wanting to build a zero-heat house that doesn't rely completely on passive thermal mass. That is, I want to be able to turn on extra warmth when I want to! But I have a bit of trouble getting my head around the various possibilities such as the type and size of thermal store and likely performance.

So I've read various publications such as the Tokyo paper but haven't seen much in the way of numerical detail. And I expect I could "do the calculations" but I also expect I'd make at least one mistake in either the analysis or the computation (numerical integration of PDEs as I understand it?). But something confirmed by experiment would make me feel more secure. So if anybody could provide any references to papers that provide models and/or quantitive analysis of actual houses, I'd be very grateful.

David, your 2000 m3 sounds a lot larger than David Mackay's 6 m radius in six months?
(<http://www.inference.phy.cam.ac.uk/sustainable/book/tex/cft.pdf> page 289)
I suspect that's telling me that it's impossible to store 5 MWh in the ground with only a 5 K delta T?

Tom, I'll be interested to see how a collector in the sunspace works out for you. I currently think that separate but fairly low-temperature facade collectors (a la Solarnor) are the way to go. It seems to me that the more decoupling there is, the better - between the collector, the storage and the building - but who knows what I'll think tomorrow.

Cheers, Dave

AGS inter-seasonal storage project - Planning Permission awaited

djh — Thu, 29 May 2008 22:05:16 +0100

Hmm, cruddy forum software! Of course the last > is not part of the URL! Dave

AGS inter-seasonal storage project - Planning Permission awaited

fostertom — Thu, 29 May 2008 23:09:52 +0100

Blimey - 14MB! but worth the wait, at first glance. A whole book - thanks djh.

Posted By: djhI expect I could "do the calculations"

That's cool - what is your trade, profession of background?

AGS inter-seasonal storage project - Planning Permission awaited

fostertom — Thu, 29 May 2008 23:15:45 +0100

Hey, this is quite a resource.
http://www.withouthotair.com/
http://withouthotair.blogspot.com/
Will keep me off the street for hours and days to come.

AGS inter-seasonal storage project - Planning Permission awaited

djh — Sat, 31 May 2008 18:20:28 +0100

Posted By: fostertom
Posted By: djhI expect I could "do the calculations"
That's cool - what is your trade, profession of background?

Well, I'm a computer geek by trade and a mathematician by training (back in the days when we used to count I, II, III, IV ...)

So, do you know of any AGS or other interseasonal storage papers with numbers? It's a nice idea but I haven't had much luck finding engineering data.

Cheers, Dave

AGS inter-seasonal storage project - Planning Permission awaited

fostertom — Sat, 31 May 2008 18:46:56 +0100

Apparently we're at the head of that game, FEA thermal modelling it more than doing physics calcs - though the software has all the physics built into its algorithms.

From http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=963 , this is about all there is. If you find anything else, please let me know:

http://www.primedesign.us/self_heating_houses/pahs_article_1.html - all you need to know, really, about John Hait's PAHS, the purist no-machinery concept
http://www.primedesign.us/self_heating_houses/self_heating_houses_files/frame.htm esp frame 18 of this Powerpoint by Engineer Joe Anderson
http://www.EinsteinCode.info to buy the ebook

http://www.greenershelter.org/index.php?pg=3 - all you need to know about Don Stephens' AGS, which judiciously uses machinery to make it work better, in more situations
http://www.greenershelter.org/TokyoPaper.pdf - ditto
http://www.greenershelter.org/index.php?pg=2 - comparison between PAHS and AGS

The penultimate one is the best intro â€“ gives the key features reqd, used in many different mixes/combinations.

AGS inter-seasonal storage project - Planning Permission awaited

davidHarris — Mon, 16 Jun 2008 17:41:49 +0100

Fostertom,
I am a bit puzzled by the idea of letting the heat into the room. If you could conduct it away instantly so that the room never heated up, great. But if the heat transfer was somewhat slow, the room would overheat quickly. Using Chukey's solar panels is fine (doesn't matter if they overheat a bit) or a greenhouse, but the main house? Have i missed something?

AGS inter-seasonal storage project - Planning Permission awaited

djh — Mon, 16 Jun 2008 23:31:19 +0100

Well, I did some fairly simplistic calculations, and I expect there are some errors but here's the rough results. I think that optimistically the losses from storing 5000 kWh in the ground might be between 140 W and 2700 W. Storing the same energy in a water tank gives losses between 210 W and 2350 W, but on a more conservative basis. Furthermore, I believe it's possible to use the losses from a water store as a heat source themselves, so its performance could be significantly better.

Against that, building large water tanks can be complicated and expensive. But I still don't see any arguments that completely persuade me one way or the other is better. I'd really like to see any evidence anybody is aware of - preferably built and measured but even models would be good.

Cheers, Dave

AGS inter-seasonal storage project - Planning Permission awaited

djh — Mon, 16 Jun 2008 23:32:50 +0100

Hmm, cruddy forum software! Again! It says "attachments" but it will only let me make one "attachment". Here are the figures for a water tank.

AGS inter-seasonal storage project - Planning Permission awaited

davidHarris — Tue, 17 Jun 2008 09:51:42 +0100

Another puzzle for me. Using UFH we are told to have insulation++ under the pipes. If using AGS am I correct in thinking that you would positiverly want NO insulation so that the saved heat in the ground can enter the house?

AGS inter-seasonal storage project - Planning Permission awaited

earthshipally — Thu, 15 Jan 2009 19:00:27 +0000

Reading this thread and others like it with great interest.

Building two "Earthship" lodges in central Scotland,

Plan on storeing lots of seasonal energy in the mass of the structure as well as the ground around it.

Clarification; The one meter per month rule average soil conductivity, Don Stevens (AGS) seems to suggest that 18' feet equals 12 months in one of his house diagrams!

Tom and Mike, do you have any further up to date information and data regarding your AGS studies?

Thanks