Energy Efficient Design
We are in the design stage of a new home.
Simple rectangle , first floor has north side against the hill side, east, west and south exposed. Second floor covers one half of the first floor leaving a exposed cement deck on the other side. All the second floor is above ground.
Entire building(except for a SIP roof) will be concrete. Most windows will be on the south side. All floors will be cement slab with pex for radiant heating when needed. Solar hot water with propane back-up.
ICF walls and deck(such as Insuldeck) was the plan but, we want to have as more mass than just the floors, to temper the heat, loss and gain. There will be a couple of interior concrete walls to support the second floordecks and will exposed to create mass.
If you were building the exterior wall, what would you do?
ICF’s or Formed concrete and then insulation on the exterior?
Jill
Replies
Precast Dow T-Mass. Working on two such designs as I'm writing this (different roof from your pref, though). From the outside in--2" concrete, 2" foam, 4" concrete. All factory built with perfect finish. All door frames and elec conduit installed. Manuf delivers and installs for about $15/sf fob factory.
http://www.international-precast.com/products/architecturalProducts.asp
Edited 5/16/2006 10:20 am ET by CloudHidden
I have looked at that system quite a bit. I have two concerns.
Real R-value where we will building. Sundance WY
Getting it there and getting it built. I am concerned that the costs of getting it to the site and finding a qualified builder will be a problem.
Please clarify "$15/sf fob factory" means cost at the factory and we pay to get it delivered and installed?
The "fob" part just meant that you pay freight...delivery charge. They install with the price of the wall. There are factories around the country. I don't represent the company, so I don't know all the locations...just the one closest to my target project site.As to R, your discussion can be with them or your designer. I believe they offer options on the insulation and wall thickness, but I don't know for sure. The standard wall assembly is fine for my project. I don't like their "up to R40" assertion, but am still fine with the assembly. Much of the advantage is from eliminating air infiltration. The insulation and the mass offer benefit if you design and site the house properly. More insulation offers benefit, of course, with the proviso that each additional inch offers less benefit than the prior inch. You gotta work the economics out for yourself and your needs...what's "enough"?A big advantage of this assembly is the connectors--they're fiberglass, so they don't have the heat transference of the assemblies that use welded wire on both sides with a through-wire. Also, getting a factory finish on both sides is a plus. Not like icf's where you still have to add something on each side for abrasion resistance, etc.
Thanks for the info!
I am going to take another serious look at T-mass. Interior mass combined with a finished surface for quick construction. It seams a win/win situation.
What are you using for your roof?
Sprayed polyurethane foam and sprayed concrete inside that. The shape will be curved--barrel vault with rounded end caps. The concrete roof/ceiling makes the structure one connected entity that should resist practically any natural disaster. The composition brings a comparable insulation/mass assembly to the roof as is in the walls.Besides the benefits for energy usage, and the inherent strength of the structure, it gives beautiful high curved ceilings instead of the typical flat sheetrock ceilings.
T-mass can also be PIP (poured in place) by a formed wall contractor. In case that makes it easier for you.
I hope to start my project in the next month - I'd be past my poured stage but I lost a month to permitting issues. My price for the foam and connectors was $3.10/sqft delivered from IA to WI - (ymmv)
Our house will be Tmass in the basement, SIP walls, Truss roof with blown in. Not as energy efficient as yours, but pretty good bang for the buck. Also an "efficient design". . .
http://jhausch.blogspot.comAdventures in Home BuildingAn online journal covering the preparation and construction of our new home.
I just got an email from the company.
"Effective April 1, 2006, Dow Building Solutions discontinued its sale of STYROFOAM* T-MASS Poured-In-Place (PIP) Insulation System, THERMOMASS* Building System and/or the STYROFOAM* Composite Connector System. As a result, we will be unable to fulfill your request for information on these systems."
http://www.thermomass.com/
Composite Tech. Corp (CTC) developed the system using Dow board. Dow thought they could do a good job marketing it, but I guess it did not work out.
As a result, CTC has brought the system back in-house but will still use Dow board.
CTC's number is - (515) 230-7577, ask for Cory.
Tell him that you got his name from someone that got his name from Rich at "Dalico" (sp?)
Sheesh, I almost had a heart attack!
I assume you are quoting per square foot of wall area - so that a 25'x50' two story with 30% windows would run about $32,000 for those materials. What are you planning on using for the roof assembly? I am looking at pricing out Lite-Deck forms for a roof/ceiling assembly on Rastra walls. Would consider alternatives that give me very high levels of fire protection. Thanks
I would like to know what opinion you fellows have of this insulated load bearing block for use in an energy efficient design. It says r3.5 per inch? http://www.greenkrete.com I am in no way associated with this company, just looking for opinions. (click on the products link on the left of the page and then on greenblok for a picture of the block)ThanksEdited 5/16/2006 5:56 pm ET by hulkster
Edited 5/16/2006 5:57 pm ET by hulkster
Think there's some smoke and mirrors going on with trying to be green. If you are going to have a thermal mass to store daily heat gains in and then release at night, you can't have and don't want any prouct with R3.5/in involved. It severely reduces heat flow into and out of the mass.
It's quite hard to believe a homgeneous concrete/insulation mix product will have an R value of 3.5!! E-mail them and ask for ASTM standard 236 tests of their product. No tests = no interest and move on!!!
>If you are going to have a thermal mass to store daily heat gains in and then release at night, you can't have and don't want any prouct with R3.5/in involved. It severely reduces heat flow into and out of the mass.Gotta disagree. Really, exterior insulation, including polyurethane foam at 6.5+/in, with thermal mass works exceptionally well. Mass needs the insulation to help effect the heat transfer in the proper direction at the proper time of day. That said, I didn't care for that block the poster linked that intermixed mass and insulatio--Greenblock--be/c (it seems to me) it dilutes the beneficial effect of each.
Hey Cloud- I've been thinking about ICFs and interior mass since you first posted the T-mass info. Is there any way to use ICFs on the exterior only, and steel or mdo or something as an interior form? I've never used ICFs, so I'm just throwing this out there. Maybe just the exterior insulation wouldn't be enough.zak
"so it goes"
Someone does make an icf with vinyl on the interior. ICF's aren't suitable for the stuff I do, so I don't research them in more detail than that.
>If you are going to have a thermal mass to store daily heat gains in and then release at night, you can't have and don't want any prouct with R3.5/in involved. It severely reduces heat flow into and out of the mass.
When I said this I was referring specifically to this block. If it's 3.5 per inch, how will it transfer heat into its mass quickly?
It's like your example of a mass wall also having R6.5 on the interior. How can that mass store the daily heat gains easily/quickly and and not allow the house to overheat (assuming it's a passive solar design)?
>I was referring specifically to this blockGotcha. It's weird to be both insulator and mass at the same time.
If it were me I'd go with the ICFs. From what you describe you'll already have plenty of thermal mass with the other masonry within the building envelope. ICFs are so easy to work with and fast. You'll have enough to do as it is.
While, I like ICF's, I am very interested in more mass. I also like the finished concrete walls.
We will be having the structure contracted up to "dry in". All other work from any siding and wall finishes to plumbing and electrical will be done by us. If the walls are in livable shape at dry in, it will allow us to get right to the rest of the building with-out delay. We can then go back to the wall surfaces when we want.
Our goal is to not have to spend "cash" to heat or cool this home. Mass and proper solar design will help with this. I do realize we can have too much mass, but this will be a large home and the radiant system in the floors will also help move the heat.
We also hope to use some liquid filled pex and a PAHS system to dump or reclaim heat depending on the system.
I do realize we can have too much mass, but this will be a large home and the radiant system in the floors will also help move the heat.
We also hope to use some liquid filled pex and a PAHS system to dump or reclaim heat depending on the system.
Jill, you've lost me. Too much mass is possible, but only with poor design. The result usually is an objectionably long period (with an active heating system running) for the interior air to reach comfortable temps. The design allowed the mass to cool too much.
You apparently have at least a passing familiarity with PAHS. Properly, the mass is never cooled beyond comfort. You're also trying to combine radiant floors with PAHS? It's a mismatch.
Are you also familiar with AGS (annualized geo solar) systems? You might find a better match with an active AGS system. Distinct similarities with PAHS, but usually combines an active system for moving heat. Almost never uses the house interior as the collector, which would work better with a radiant floor. Dearth of information about the nuts and bolts of the design (short of hiring the originator), but there's a guy in the NE currently trying to get that resolved.
Doesn't sound as if you've done heat loss, solar gain calculations. While your proposal doesn't appear to have any major flaws, I'd find it comforting to have a better idea of projected performance, particularly when you're adding active systems. Your climate is very similar to the original PAHS'. Are you getting away from Hait's design due to your second floor and not wanting to deal with that much backfill? Bear in mind that PAHS can look like about anything. Ignore Hait's architecture. It's the system that's important.
2 story PAHS can work. I designed one here for a client. The engineering for that much backfill got interesting. After scaring the crap out of the engineers I learned how to deal with it inexpensively with a technique from New Zealand. Unfortunately, was never built.
http://paccs.fugadeideas.org/tom/index.shtml is very simple PAHS system (if you haven't seen it). It's a page a guy in Florida put on his web site about our home. I now know a bit more about how our place works, but that'll give you the gist.
Good luck with your place.PAHS Designer/Builder- Bury it!
I have seen your home! Itis one of the reasons I have considered PAHS.
We are just finishing the house design, so no calcualtions yet. I like the idea of PAHS but not the earth tubes. We are going to be using evacuated solar tubes for our hot water. We are also putting in radiant tubes in the floor to move heat from the south side of the building to the north. The solar hot water will most likely create some excess in the summer. Usually we would put in a ground loop or loop to a pool or hot tub as a dump for the excess. I was hoping that we could somehouse use a form of PAHS to move and store that heat depending on the need.
As you can see, we are still learning and incorporating things to fine tune the final design.
Jill
Hi Jill,
LOL... Hard to not like the PAHS idea, totally passive heating/cooling. Thanks for the compliment.
I didn't use earth tubes primarily for fear of fungal incubation. UV treatment will solve that, but I didn't/don't want to add an active system. For you, in an arid climate, not much to fear. OTOH, if you're only concerned with storing excess heat, you don't need earth tubes. A common misconception is that earth tubes are a requirement for PAHS.
Your plan still isn't clear to me. Perhaps I'm dense. PAHS doesn't do a good job of moving heat from here to there. Remember: 6 mos for 20 feet. An active system might be better for you. That's why I mentioned AGS.
How far are you wanting to move heat? With a decent air system, preferably thermosiphon, 40' is no stretch. Pretty sure that can go considerably farther, but my experience stops at a 40' span. The steel roof structure gets very interesting about there.
The AGS originator is now (as usual) saying he's too busy to provide details but promises on Wednesday to have a response. The questioner is someone who's been involved with earth heat storage for awhile, not an unknown. I'm hoping that there will finally be some real information released. This is an old concern. Not something I pretend to fully understand. If it's something you want to tune in to, give me a buzz. Last time this came up, there was no information dissemination so I'm making no predictions.
As a PAHS enthusiast, I'm biased. But a functioning active system will somtimes be more appropriate, as (apparently) in your situation.
Please continue to make the effort to get a good understanding of the systems involved before you build. Not just for your success, but also to further the understanding of the whole process, particularly earth heat storage.PAHS Designer/Builder- Bury it!
The liquid filled pex in the floor will move heat from the south side of the building where windows will warm the floor to the north part of the building where sunlight will not directly hit the mass. It just moves the heat a bit faster than a passive system will. It will also "warm" the floors a bit in the winter if we want( such as in cold mornings).
In our present house, we have radiant in cement floors. I have it set up so that in the summer I can switch the flow of the water. In the summer I run all the water through the floor before it hits the water heater. It does raise the temp a few degrees and while I would not say it cools the house, it does keep your toes cool.
We will have no other "extra" heat in the new house other than radiant.
Jill
Hi VaTom,Quick question for you: How well would the PAHS system work in the deep South? Seems Md and Va are pretty evenly matched between winter and summer, but what happens when you get between Florida and East Texas?FYI, the average annual air temp in Tyler, TX is somewhere around 65F. Does that mean you could expect that temp? Also, does the higher humidity preclude PAHS?Thanks,
Ken++++++++++++++++++
The average pilot, despite the somewhat swaggering exterior, is very much capable of such feelings as love, affection, intimacy, and caring.These feelings just don't involve anyone else.
Hello Ken,
Love the internet. I see Tyler has been ususually warm so far this yr. But average annual heating degree days are 2105. Average cooling degree days are 2490.
We have 4166 heating, 1131 cooling. These are the numbers you want to consider for design.
The PAHS thermal flywheel will work in Tyler, easier than here. Notice how unequal we are (heating/cooling) and it still works fine. The original PAHS was Missoula, extremely unequal. No problem.
Humidity is a big deal, as you know, but has little to do with PAHS other than complicating earth tube design. I've been asked how I got annual heat storage without earth tubes. Not a problem. With PAHS, the house is the collector. In your case, you'd want it to be a smaller heat collector (not necessarily smaller house) than mine so you could dump more excess heat into your mass.
All this is extremely slow, house temp changing more than 3º/day is unusual. Everybody else here is running ac by now with days in the 90's, 71º out when I got up this am. We're at 70-71º inside. Our mass hit its lowest temp late spring, just in time to keep us cool until fall. Pretty sure I mentioned that this is not high efficiency, there's a large amount of heating/cooling going on. Just that we do nothing to make it happen.
We're serious about dehumidification, an active system that I haven't found a better replacement. Costs us $30/mo for the season- and yes, I'm complaining. A major improvement I installed a few yrs ago was a heat pump water heater. Used seasonally, it provides 50% of our required dehumidification as a byproduct of heating water at roughly 3x the efficiency of elec resistance. Would clearly work well there if your house is configured appropriately. Very efficiently takes heat out of the air to heat your water. Byproduct is (free) cool dry air. Doesn't get much better than that in a humid ac climate.
Did I mention I like PAHS?
Edit: Oops, just looked at your profile and found you don't live in Tyler. Planning a move?
PAHS Designer/Builder- Bury it!
Edited 5/30/2006 9:39 am ET by VaTom
Hey Tom:
Another question from a Texan, and I do live in Kerrville Tx...west of San Antonio. I am not sure about our heating/cooling days, but cooling is a lot more of concern than heating.
I have looked at earth tubes, still neutral at this time, and using stacked concrete block building with surface cement. In fact, I am waiting on the building permit to build my shop using that method. I discovered it at naturalhome.com
Still at the curiousty stage now.
john
Hi john,
There's an underground home near here, post&beam with dry-stack block infill. Maybe 20 yrs old, owners think it's great. Definitely not PAHS.
I knew nothing about cast-in-place concrete when I started, considered dry-stack. Now, I can safely say I see no reason to use block if there's a readymix plant in the vicinity. Concrete forming just isn't that difficult and the product is superior. DIY friendly.
Afraid I don't understand your question. Are you asking about degree days for Kerrville? A quick search didn't get Kerrville, but San Antonio has 1644 heating degree days and 2996 cooling degree days. Didn't list typical rh. That gets a little more difficult for PAHS (I wouldn't do earth tubes unless you can get safe dehumidification that way). You'd want zero solar gain and extra heat loss from the mass during winter to get an annual flywheel revolution with comfortable temps. No problem, just needs an adequate design. Rather than concentrating on heating, you'd want to look at using your brief winter to cool off your mass.
The mass doesn't care. It's insulated from air temps. More than just a big pile of dirt, there really is a heating and/or cooling system at work. Just totally passive. PAHS Designer/Builder- Bury it!
I was not really sure if I had a question ;>)
but I do think San Antonio numbers are close enough mine to use for the time being at least. I will have to look more into the cast in place that you are talking about. I have concrete ready mix plant nearby, so that part is no problem.
Thanks for the info.
john
I will have to look more into the cast in place that you are talking about.
My place was built with two helpers who knew less than I did. I'd read the book: Concrete & Formwork, ISBN0-910460-03-5. We used a pile of CDX ply with snap ties and wedges from a concrete material supplier, very old fashioned = cheap.
If you do it, have a spare vibrator on hand for every pour. They don't fail in storage.PAHS Designer/Builder- Bury it!
Hi, thanks for the reply.Yep, thinking of moving back there at some point, all depends :-)After the spike in temp and humidity this weekend up here, just got to wondering how that worked with PAHS. And after coaching a soccer game tonight just east of DC I'm real interested in dealing with humidity.Been interested in earth-sheltered homes since the late seventies and just wondered how you dealt with humidity.Just to make sure I understand, are you saying the flywheel effect will work anywhere -- but in high humidity you will have to have active dehumidifition? You just don't have to have cooling AND dehumidification?++++++++++++++++++
The average pilot, despite the somewhat swaggering exterior, is very much capable of such feelings as love, affection, intimacy, and caring.These feelings just don't involve anyone else.
Yup, it's hot and humid here a couple hrs' SW of DC too. Outside, that is.
Earth tubes are the "official" way to deal with excess humidity, and fine tune PAHS. Fear of fungal incubation (legionnaire's disease, et al.) scared me off. I now know how to purify the air with UV, but that's adding an active system and maintenance. Another thought was to use copper pipe for the earth tubes, but nobody I know has experimented yet.
Underground or above grade, humidity is humidity. Needs to be controlled both places. The only real difference is that we have no need of ac, therefore I don't get that dehumidification.
Well, there's also that very low 70's indoor temp which raises the relative humidity by cooling down the air I bring in for our .5 ACH. This time of year we are a little cooler than most houses using ac. Or maybe you have your ac set at 71º, in which case there's no difference. In a couple of months when our mass gets warmer that will change. We'll have lower rh without doing anything except letting the mass get ready for winter.
The flywheel has nothing to do with humidity, totally different subject. Most houses have no flywheel to speak of, but everybody has humidity to deal with. Yes, the flywheel can work anywhere. Including Alaska, according to one BTer. Sounds plausible, but I haven't look at any numbers. Hadn't actually looked at Texas before you asked.
Safe passive dehumidification is the holy grail. Actually, there's a process I've looked at a little, no conclusion, called air wells. The international society is primarily interested in using dew point to condense water out of air as a water source. What they ignore is the byproduct, cool dry air, which is at least as important to me. Not unlike heat pump water heaters.
Thanks for your interest.PAHS Designer/Builder- Bury it!
Well, there's also that very low 70's indoor temp which raises the relative humidity by cooling down the air I bring in for our .5 ACH.
Tom: Why don't you reduce the ACH so that you don't have to dehumidify so much. You're bringing a lot of water in with that much air exchange, especially when it's really humid oputdoors. Save $$$ on running fan + dehumidifier (or does the DHW heat pump just provide enough hot water to balance the need for dehumidification?)
You're right. I've considered reducing ACH.
Not real convenient so I haven't done anything. This week I noticed. Very good guess. When DW's not on the road we use enough hot water to mostly make up the difference. Probably a way to time the two concurrently, but that starts looking complicated and something else to break. Next house gets a utility room. Fan cost is negligible, dehumidification isn't. But we're picky about rh levels, have no intention of tolerating mildew.
Still a little suspicious about air quality (with lower ACH), but there's only one way to find out...
Believe I once before asked. You know much about radon?
You actually waded through all that PAHS stuff?
PAHS Designer/Builder- Bury it!
A bit!!
Radon occurs mainly in granites and shales, if I remember correctly. If its not in the aggregate for your concrete, then it may come in cracks in the floor, a gap around a plumbing stack in the floor, sump pit for P-traps for showers. baths, etc.
A test will only cost $80-$120. Do a longterm test, not something over a few days or a week. Based on the levels found, the rcommendations will vary from immediate action required to do something within a year or two .
If you have a positive test: Seal up all cracks, gaps in any concrete in contact with soil. Run HRV under positive pressure so as to force air out of the house into soils rather than sucking air in.
Another technique is to depressurize under slab using an inline fan with duct installed to drainage layer. This air gets vented to the exterior. Check that the negative pressure extends fully under the slab. Ocassionally, another fan system will be needed to fully do the job.
Edited 5/31/2006 7:25 am ET by experienced
LOL, I should have been more specific. Thank you. Most of that I already knew.
We have concrete, complete with cracks (duh). Particularly the floor, done by a guy (supposedly the best in the area) I'd never recommend. Poly under, but it obviously is going to leak some. This is a moderate risk radon area.
The question I didn't quite make clear, if reducing our ACH would likely make much radon difference. AND, given our .5 ACH, is there any point to a radon test? I obviously haven't. The kit instructions I've seen want you to stick it in your basement, close the doors and windows, and leave it in undisturbed air for awhile. Makes no sense here. This must be the short term type you're saying isn't adequate?
This is one of the reasons I positively pressurize the house.
PAHS Designer/Builder- Bury it!
Edit: Forgot to mention that we recently had an older friend over who, once again, started praising our air quality. Didn't really want to leave. On the drive to her home she quizzed me about air systems, primarily asking if such a thing could be adapted for a standard house with H AC (no V). This is typical here, unfortunately. An operable window is deemed to satisfy code required ventilation. I bugged the building inspectors on the issue. Got nowhere.
Looks like I need to start interviewing HVAC guys to try to find someone to recommend. Far from the first time this has happened. Needle in the haystack. <groan>
Edited 5/31/2006 8:55 am ET by VaTom
Looks like I need to start interviewing HVAC guys to try to find someone to recommend. Far from the first time this has happened. Needle in the haystack. <groan>
No! No! No! In the land of great entrepreneurs, looks like you need to fill out your vent. knowledge, start and manage a good ERV/HRV company where some real $$$$ can be made since there will be little competition.
Thanks, but no thanks. I'm old enough to know me pretty well. Lots of ways to make a living and I like what (little) I'm doing just fine. Acquaintance in Oregon twisted my arm hard trying to get me to promote my PAHS building. Same (lack of) success.
You're right about the opportunity. Wanna move down? I'll send referrals. Hey! You could satisfy your dream and push heat pump water heaters here. And if you wanna build passive heating/cooling systems, I'll show you how simple it is. What a deal! This is a wealthy area. Blanche isn't, but she'd pay you. Or at least offer to trade you from her large art collection.
Another friend made the mistake of consulting with me about the extravagant house he was having built. His builders' preferred H_AC guy told him he'd open the exterior door a couple of times/day and that was all the ventilation he needed. After that the search was on. Sometimes a little knowledge can be a dangerous thing. I warned him that involving someone (me) not directly connected to the house was trouble. He will be getting a substantially better house, but he had to earn it. And still doesn't have the indoor pool. Looks like I'll have to do that in a couple of yrs- if I find the time.PAHS Designer/Builder- Bury it!
I've heard mention a few times of the water heater heat pumps. Where would I go about researching these?
Just the 2 of us living here in NH in a small ranch - ~100 sf upstairs, half the basement finished. We use a dehumidifier in the basement from sometime in June into Sept. in order to keep it from getting soggy & smelly. Seems to cost about $30-40 per month.
Wondering if the heat pump idea would make sense to help with dehumidification and supplement the electric HWH we have now (which is fairly new).
Don
Likely your basement is too cool. I don't use my HPWH until we're consistently over 70º. But I'm no expert and there may be a HPWH that likes cooler temps than mine does. There was a great gov't site on them, but it disappeared. Best I've since found is http://www.energy.wsu.edu/ftp-ep/pubs/building/res/ht_pmp_water_htrs.pdf
Our HPWH is plumbed into our standard elec tank heater, keeping the elements from being turned on. I was looking for roughly 1/3 elec consumption when I bought it. Big surprise was the volume of dehumidified air. When the two of us are home, gives us half the dehumidification we need for our 20,000 cu ft with .5 ACH in a humid climate.
Oh, if your water heater has electronic controls (Lowe's best), my HPWH won't work automatically with it. The non-electronic models work great. Uses the tank thermostats to turn on and off the HPWH. Mine's an E.tech from Crispaire Corp in Cordele, Ga. If/when it dies, I'm immediately getting another one. This one was new-old stock (no warranty) on ebay, paid for itself in just over one season. I'm getting cheap water heating and free dehumidification. If your basement's warm enough and you have air circulation, jump on one.PAHS Designer/Builder- Bury it!
Thanks for the info.
This fits into the general theme of our house - energy efficiency isn't all that great, but payback for major improvements isn't really there either.
Don
>You're also trying to combine radiant floors with PAHS? It's a mismatch.Tom, let's say the challenge was put to you to provide heated floors with PAHS. Say the client just adored a warm floor in the winter and could not or would not live without it. Could it be done in a way that would take the chill off? If ambient temp is 68, then getting the floor to 80 or so? Rule of thumb is that floor temps will be 10 degrees above ambient for a steady state rfh system. Could it be done, or would it mess up the PAHS system balance? I'm guessing you're saying (via "mismatch") that it's unnecessary as a heat source, but would it somehow be a negative influence as a convenience? And you have a wood-stove or fireplace iir, so could a minimal rfh system (running modest temps) be an alternative for those with no interest in having a wood pile?
Edited 5/18/2006 12:20 am ET by CloudHidden
Highly unlikely a PAHS client you're describing. You're talking about someone who wants all the creature comforts available from "modern" HVAC systems. That much interest in an active system is counter-intuitive for a PAHS fan. One of the differences between you and me for instance.
Can be done of course. It would decrease the efficiency of PAHS. As you know, changing the temperature differential affects heat flow. Result will be increased reliance on the radiant heat source.
Further, better radiant floors have insulation under them, another problem. PAHS insulation is only on the outside of the heated mass. Simplicity personified. That under-floor insulation would be very detrimental both winter and summer.
Introducing an active system, particularly radiant flooring, will generally make AGS a better alternative, assuming some realistic numbers are forthcoming. If not, an interesting area open for experimentation. Ideally with a knowledge of similar failed systems.
Lots of ways to get the small supplemental heat we occasionally enjoy, including making the house more heat retentive. Our next house will be even better thermally designed, but not more insulated. PAHS Designer/Builder- Bury it!
>You're talking about someone who wants all the creature comforts available from "modern" HVAC systems.That's an interesting perspective. If we accept the premise that each method of building forces the client to compromise or give up on something, it'd be fun to compile a list on what the client is giving up with the different approaches. Philosophically speaking, I wonder if people realize what they are giving up, rather than just what they're getting. For example, how many people building a McMansion in FL really think and acknowledge, "Yes, I'm paying 500k to get the look that will impress my neighbors, and I readily accept that it will not provide me protection from hurricane force winds." Or whatever. Having to forego heated floors, or having to forego flat roofs and gable ends...I wonder how conscious homeowners are of the characteristics they're giving up to get something else.
"I wonder how conscious homeowners are of the characteristics they're giving up to get something else"
I think that is exactly the process I am in! I am balancing what I want with, my budget and my needs.
Wants- low future energy needs, a living enviroment that keeps me at a temp. that will I am happy with, floors that don't always require slippers.( not to hot not to cold!) A home that will appeal to the next buyer(If I ever have to sell) and not be a dark dank cave.
Needs- Timely construction that will be good in a fire situation. A budget that I can afford.
I am willing to put my money into a quality structure and give up the extra's( cabinets andinterior walls) until I can afford them.
Jill
Have you considered tip up concrete walls like the ones used to make factories and warehouses?
The outside can be insulated after they are up.
I am considering them. We liked the idea of a finished product. I just got prices back from on company. They were "crazy". I am waiting back on another. My problem right now is finding companies local to me. Northeastern WY.
Our other option is just have cement walls formed and then insulate the outside.
Jill
Hi,
"If you were building the exterior wall, what would you do?
ICF's or Formed concrete and then insulation on the exterior? "
Here is another possibility:
http://www.eere.energy.gov/buildings/building_america/pdfs/32765_vangeet_house_barley.pdf
Its a 1.8 MB pdf.
Describes the Van Geet home in CO. Uses dry stack concrete masonary units with 5 inches of rigid foam insulation outside, and an outer layer of stucco. This is a Building America research home -- some good design data is provided, including a simple metric on how much thermal mass is good. The home acheives about a 70% energy reduction over current code.
A bit more here:
http://www.builditsolar.com/Projects/SolarHomes/constructionps.htm#Stack
I guess the thing I am not clear on, and the paper does not describe is how the rigid foam is attached to the concrete blocks?
Gary
That first article is GREAT!. I have to reread it and study it but It has wonderful info.
Have not got the the second one yet!
jill
Here is another article I found.
http://mha-net.org/msb/docs/surfbond.PDF
Thats a really good writeup -- thanks -- Gary
Updating!
I have found two Thermomass(T-mass) companies close to our new home location.One is a precaster. One is a cast on site. I don't have numbers yet but working on that.
Now I need to do the calculations on mass and heating cooling needs. Could someone point me in the right direction to find the info to do this.
Jill
Hi,"Now I need to do the calculations on mass and heating cooling needs. Could someone point me in the right direction to find the info to do this."If you are looking for something that will predict the detailed thermal performance of your house with high mass walls (as opposed to just a simple furnace sizing program), then you might try the HEED software.
It is a full, hour by hour, simulation. It is capable of modeling various levels of thermal mass in walls, floors, and ceilings. I've not tried it for this, but it claims that both the heat absorbing and thermal lag properties of the mass surfaces are modeled. It also does all the solar gain, overhangs, ... type things.It was written to help California rate payers do energy cost saving studies, so the first level of the user interface is very easy to use -- you can define a full house in 5 minutes.
There is a whole other level hiding in the "Advanced" tab that allows you to do such things as defining additional thermal mass (and much more).There is not a lot of documentation on the advanced features -- about the best thing is to go to the screen of interest (eg thermal mass), and click the help button.The Evaluate tab provides a whole slew of graphic output for temps, ventilation, ... I find them nice, but a bit frustrating when you really want numbers -- if you persist way down the list there is some limited numeric output offered.You will need to separately download a weather file for your city from the EnergyPlus site -- the HEED site tells you how to do this.Best of all its FREE!!
You can get it here:
<http://www.aud.ucla.edu/heed>http://www.aud.ucla.edu/heed
As luck would have it, they just did a major new release yesterday.
If you give it a try, please let us know how it works out.Other options might be Energy10 (not sure how flexible it is on thermal mass) $300ish. EnergyPlus, which is also free, and can model just about anything, but has a MtEverest like learning curve. Or, to use the techniques described in the VanGeet house paper posted above.Gary
http://www.BuildItSolar.com