New home builder looking for some advice
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T-SoxUser is Offline
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18 Oct 2016 10:33 AM
First off I'd like to say thank you for this sight! My wife and I are planning on starting a new house in the next few months. In researching building design I stumbled upon this sight and I've learned a TON. Had I not found this place I would have just slapped up the normal energy hog home and thought nothing of it. We are trying to build this home mortgage free so the budget is tight. I plan on doing most of the work myself as I worked in construction for awhile (but that was 10 years ago). The house we are building is a simple 32x52, single story rectangle ranch with basement. The basement will eventually be finished but not right away. I need to preface all this by saying that I will have to pick my construction techniques carefully. I am drawing the plans myself so they won't have an Engineering stamp. This is fine and will save us several thousand dollars but I have to stick with known building practices. I've already spoken to the building inspector and he has been pretty open to most things but I need to provide the documentation (building code) to back up anything that isn't Engineered. After doing some reading here, my plan is posted below.
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18 Oct 2016 10:33 AM

ICF basement walls. I have experience with ICF. I have built several houses and commercial buildings with it. I know the local Logix block supplier so he is willing to loan me the bracing for free if I buy the blocks.


The floor slab will get 2-3" of Poly Iso under it.


The sill plate for the second floor will be held back to the edge of the Concrete core on the ICF.


The second floor will be 2x6 walls with Rockwool insulation(R 23) covered outside with a 2-3" layer of Poly Iso. With the sill plate held back, I can run the Poly Iso right down to the outside foam on the ICF and seal it to help with the thermal bridging on the floor. This should get me close to R40 walls very economically.


The roof with be trussed. It will be sealed and blown full of Cellulose. I'm guessing around R50-60.
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18 Oct 2016 10:46 AM
This brings me to my dilemma...

My plan was to do Radiant heat in the basement slab and staple up under the main floor. I have some experience with this and my wife the warm floors some of our friends have. Plus I was given a large amount of O2 Pex and aluminum plates by a friend that over bought for his house. I have almost enough to do the whole main floor.

I've had a few heat loss Calcs done on the preliminary design and they came in around 18-22k BTU's.

From the things I've read here, I might want to rethink this plan. Reading about Mini splits, heat pumps ect ect has gotten me wondering which way to go.

What would the experts here recommend? I understand this is a 1000 foot view. I'm just looking for some kind of direction to keep moving forward.

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18 Oct 2016 11:05 AM
Sorry for all the rambling but some more info I thought was pertinent. I live in southern PA, Zone 5. Mostly heating climate and the lot I will be building on is windy pretty much all of the time.

Thanks
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18 Oct 2016 11:05 AM
Poly iso is not rated for direct ground application. XPS is the standard in 15-25 PSI for residential.

Still a room-by-room Manual 'J' would be in order before committing to any equipment selection. I design many homes, new and used, and used a mini-split in my home and shop but they are not for everyone .

It can be difficult to design with a mini-split for multi-zone, multi-level structures. You also lose the ability to integrate humidity and filtration control. I have turned to Unico for these tasks in many of my designs.

Where will you build?
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18 Oct 2016 11:09 AM
I forgot about Poly Iso not being rated for ground contact. You forget a lot in 10 years. I guess that's why I'm here. XPS will be used under the slab.
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18 Oct 2016 11:23 AM
A slab HR emitter is as good as it gets for both acquisition cost and HR emitter performance. I would recommend EPS under the slab in lieu of XPS. If you already have the plates for a below-floor HR emitter, your acquisition cost for this floor becomes reasonable too. You will take a HR emitter performance hit with this below-floor emitter, but if you don’t add much R-value in how you finish this floor, you will be okay.

HR floor heating can be accomplished with heat pump systems (e.g., Daikin Altherma, etc.), but your low load building may make finding one of an appropriate size and acquisition cost challenging. NextGen makes some very nice HR appliances for low load applications (4, 6, 8, 12 and 14.4 kW) that takes the complexity out of the install and are very DIY friendly if an electric boiler makes sense in your location. The 6 KW is rated for 20,478 Btu/h. Otherwise, a mod/con gas boiler might be something to consider. You certainly need a good room-by-room heat loss analysis before designing a HR floor heating system. There is information about all this and free heat loss analysis and HR design software on our website.
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18 Oct 2016 11:45 AM
OK,

That is good to hear. My Wife will be happy.

Gas is a no go on this particular lot. It's remote so gas would need to be Propane, trucked in and held in a tank. Very expensive around here. Electric would be nice as it's almost a set and forget solution and with the windy lot, I am looking into a possible solar / windmill system in the future. Electric is around $.06 kwh here.

Believe it or not, the Next Gen Boiler was at the top of my list. They seem to be very well priced for everything included.

A room by room heat loss analysis is on my to do list as soon as I finalize the interior design. I have used some of the calculators on your site but they can be intimidating for a novice. I do appreciate them being available though.
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18 Oct 2016 01:08 PM
The flooring plan is an engineered Bamboo throughout the house with tile in the bathrooms. From what I've read Bamboo is an R0.50. This along with the subfloor should work out to around an R1.60 in most of the house and R1.12 or so in the bathrooms. This should work our good so that the bathroom floors feel slightly warmer with the same water temp. Or at least that's the plan.
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18 Oct 2016 02:37 PM
One more thing that confuses me (one of many)...

I know from reading here that I will need to look at mechanical ventilation. What should I be looking at that is DIY friendly?

I have read a lot about HRV's but I'm not sure if that is within my capabilities or not.
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18 Oct 2016 05:00 PM
A few comments...

XPS is blown with HFC134a (automotive AC refrigerant) mixed with a few other HFCs, that has a lifecycle greenhouse gas footprint over 1000x CO2. As it loses its blowing agents over a few decades it's performance drops from the labeled R5/inch to R4.2/inch. EPS is blown with pentane (about 7x CO2), and is R4.2/inch on day 1, and pretty much ever day thereafter. And it's cheaper per labeled-R than XPS. The only reason to go with XPS in a radiant floor application is if you are stapling the PEX to the foam, and only the top inch needs to be XPS for that better staple retention.

There are many reclaimers of roofing foam that can supply sub-slab EPS, XPS or wall polyiso at a fraction of the cost of virgin stock. Any reclaimed goods are greener than virgin stock, since the envirnomental hit has already been taken- you're just extending the benefits. For design purposes, assume any reclaimed XPS is it's fully depleted R4.2/inch, and any reclaimed polyiso should be assumed to be R5/inch when used in an exterior sheathing application in a zone 5 climate. Search the local craigslist for the terms [rigid insulation], and you'll often find a local supply. Stock comes & goes, so if you find the right stuff at the right price, nab it and store it (off the ground, protected by tarps.) In my neighborhood the typical price for reclaimed 3" fiber faced polyiso in near-perfect condition is about $15-20 per 4x8 sheet, but I've seen it as cheap as $10. Reclaimed roofing EPS or 2" polyiso is usually $10-12 /sheet @ 3". There is at least one vendor that ships anywhere in the lower 48 (and I think they have a depot in WV somewhere), which is Nationwide Foam ( http://nationwidefoam.com/ ), but the shipping adds up. Always buy 10% extra for the occasional sheet too damaged to be of much use, or installer errors, etc.

As you noted, when you place the foundation sill properly you can have the exterior of the wall-foam co-planer with the exterior of the ICF foam for a perfect thermal break over the foundation sill & band joist. Use an EPDM sill gasket as a capillary break. If you are in termite territory, use copper Z-flashing from the structural sheathing out over the ICF foam. It will be a thermal bridge, but it will keep termites from tunneling through the foam into your framing unseen.

Caulk the sheathing to the framing in every stud bay for air tightness, making the sheathing the primary air barrier.

A 2x6 16" o.c. R23 rock wool wall with half inch CDX and half inch gypsum will run about R15 "whole wall" after accounting for the thermal bridging. Adding 3" of polyiso adds another R15 (derated for climate), which makes it really an R30-ish wall, not an R40 wall, even though it might be close to R40 at center-cavity. But that's OK. In a zone 5 climate that is sufficient wall performance for a Net Zero Energy house with a PV array that fits on the roof, if the other factors are up to snuff. See Table 2, p10 of this document:

https://buildingscience.com/sites/default/files/migrate/pdf/BA-1005_High%20R-Value_Walls_Case_Study.pdf

Note, those are "whole assembly" performance numbers, not center-cavity. You would be looking at the row for zone 5.

For tips & details on hanging thicker foam see: http://www.greenbuildingadvisor.com/blogs/dept/musings/how-install-rigid-foam-sheathing

For homes at that performance point it's usually cheaper and easier to use ductless (or ducted) mini-split heat pumps for both heating & cooling rather than staple up floors. In southern PA it's about 1/3 the cost of heating with a condensing propane boiler. There are hydronic chillers (eg Chilltrix) that could fill the bill too, but it's a lot more expensive to install, and comes with some design risk, whereas mini-splits are a "system in a can", with fewer ways to screw it up (though the more idiot proof they make things, the more creative the idiots become. :-) ) An IRC code min house that size will have a heat load at 0F of about 27,000 BTU/hr. If you build to the BA-1005 rough specifications you'll be under 20,000 BTU/hr, and could heat the whole above grade floor with a 1.5 ton mini-ducted Fujitsu. The basement could be heated with a water heater (electric or propane) if you run the PEX in the slab, but the heating load will be ridiculously low. A half-ton Mitsubishi FH06 would more than cover the load, but if it's broken up into several rooms a 3/4 ton mini-ducted Fujitsu would probably be a better choice.

The Lunos ductless HRV system works pretty well if your floor plans are reasonably open, about $1000 per pair and are an easier DIY than bigger deal ducted versions. You'd want at least one pair for the upstairs, and another for the basement. You can probably wait on the basement pair until you're using it as living space, but if the location tests high for radon it's time to pull the trigger on the basement ventilation.

https://foursevenfive.com/product/lunos-e%C2%B2/

Got a ZIP code? (For estimating outside design temp, solar radiant potential for roofop PV, and other climate particulars.)
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19 Oct 2016 07:56 AM
Pex staples into type II or denser EPS insulation just fine with the barbed staples and holds tight through a floor pour. other than that mistake, Dana gives you good advice.
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19 Oct 2016 02:56 PM
Thank you both!

It looks like I'm at least headed in a good direction. I guess even a blind squirrel finds a nut once in a while!

I'll do some more reading on the insulation. I like the idea of staying Green whenever possible but the budget will constrain some of these decisions unfortunately. If $ wise it makes sense, I'm all for it.

I figured the walls would come in somewhere between R30 - R40. That's why I said Close to an R40. I guess it was closer to R30 than R40 than I thought.

I know of two guys within a few miles of the site that sell foam insulation. One sells reclaimed Poly Iso stock (he may be able to get EPS) that is like new for $20 a 3" sheet. The other sells "factory seconds" for $18 a 3" sheet. I'm not sure which one is better?

I'm not opposed to any heating system. I'd like to find something DIY friendly though. I'll be doing as much as I can myself to keep to our Mortgage free goal so something not complicated to design and install. I have no problem doing my homework to learn though.

Same goes for the ventilation.

I looked at the Lunos system. I like the simplicity of it. I'm guessing I would have to allow for these in the ICF or risk a nightmare later on.

We're building in Zip code 15530. I would post up a layout but I can't figure out how. It's a mostly open Ranch with central Kitchen, Dining and living room area. Master bed and bath to one side. two bedrooms, a laundry and bath to the other. As far as the stapling the tubing, I will probably wire mesh the floor and zip tie the tubing to the mesh.
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19 Oct 2016 03:16 PM
Ok, I got a little more info on the insulation.

Vendor A sells reclaimed stock. He doesn't know when he will get stock or what he'll get. His is paper backed Poly Iso. Price is $20 a sheet for 2" Poly Iso which he has right now. 3" is $22

Vendor B has "factory seconds". He can get whatever I want. He sells mostly foil backed Poly Iso but he can get XPS for sure and thinks EPS wouldn't be a problem with a little bit of a heads up when I need it. Price is $20 a sheet for 3" sheets of either.

Vendor B is also only 2 miles away for the job site.
If I'm willing to drive a couple of hours I can get 3" EPS for $16 a sheet.
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19 Oct 2016 03:39 PM
Ok, one more thought. Sorry for my ranting but I'm really excited about this.

Would I be better off switching out the Rockwool for Wet sprayed or dense packed Cellulose? I'm not sure I can even find anyone that does wet spray around here (maybe I can rent the equipment?) but I put Cellulose in our current home with good results.
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19 Oct 2016 05:43 PM
Posted By T-Sox on 19 Oct 2016 03:16 PM
Ok, I got a little more info on the insulation.

Vendor A sells reclaimed stock. He doesn't know when he will get stock or what he'll get. His is paper backed Poly Iso. Price is $20 a sheet for 2" Poly Iso which he has right now. 3" is $22

Vendor B has "factory seconds". He can get whatever I want. He sells mostly foil backed Poly Iso but he can get XPS for sure and thinks EPS wouldn't be a problem with a little bit of a heads up when I need it. Price is $20 a sheet for 3" sheets of either.

Vendor B is also only 2 miles away for the job site.
If I'm willing to drive a couple of hours I can get 3" EPS for $16 a sheet.


Factory seconds polyiso is usually a cosmetic issue, say a dinged/torn facer or a bit of surface waveness, but it's fine. At $20/sheet for 3" is about 1/3 the cost of the A1-prime stuff. Most foil faced polyiso is 1-1.5lbs per cubic foot density, which is fine for walls, and easier to air seal (with a high quality aluminum tape, such as Nashua 324a, sold at box stores) than fiber faced goods.

Most fiber faced polyiso is 2lbs density, and is harder to ding-up, and has a higher compression strenght needed for "walkable" membrane roof insulation. If you were planning to do a cathedralized ceiling with foam above the roof deck, it would be preferable than the foil faced stuff.

$20/sheet for 3" EPS is pretty steep for factory seconds. $16/sheet is more like it, but, I'm used to seeing it even cheaper than that. $20/sheet for 3" XPS is in the range of what I've seen for factory seconds or reclaimed goods though. Whether it's going to be worth the trip to save $4/sheet for 3" EPS is your call.

The difference in whole-wall R between R23 rock wool and damp sprayed or dense packed cellulose is less than R1. The R-value of the cellulose will be about R20, but at 2.5lbs (typical damp sprayed dry density) or 3.5 lbs (dense packed) it has enough thermal mass to have a small but measurable effect, which improves net performance. From a fuel use point of view it's pretty much a wash if the rock wool is installed perfectly. It's easier to get a perfect full-fill/no-voids installation with cellulose. Cost wise dense packing can be pretty expensive compared to batts or damp sprayed, so get quotes if you're cost sensitive. (Who ISN'T cost sensitive? )

The 99% outside design temp for Berlin PA is going to be around +8F, give or take a couple which isn't a very severe constraint for mini-split heat pumps. (see: http://articles.extension.org/sites/default/files/7.%20Outdoor_Design_Conditions_508.pdf ) Propane is running about $2.65/gallon in PA right now (cheaper than the 5 year average), and electricity is running about 13.75 cents/kwh.

Burned at 95% efficiency in a boiler the 91,600 BTU/gallon source fuel energy delivers about 87,000 BTU of heat into the heating system, so for a million BTU of heat (MMBTU) it takes 11.5 gallons, which at $2.65/gallon costs ~$30.50/MMBTU. To that is an additional cost for pumping & control power.

A right sized mini-split will have a seasonal average coefficient of performance (COP) of better than 3.0 in your location, but if you screw it up sizing wise it may only hit a COP of 2.5. A best in class mini-split can hit 3.5, but for now let's run the numbers at a COP of 3.

Electricity in a resistance heater delivers 3412 BTU/kwh (it's metric to English units constant). So per MMBTU it would take 293 kwh/MMBTU to heat with electric baseboards or an electric boiler, which would cost ($0.1375 x 293=) $40.20/MMBTU, which is more expensive than propane. But at a COP of 3 it only takes 98kwh, at a cost of (98 x $0.1375=) $13.48/MMBTU, which is less than half the cost of heating with condensing propane.

At a COP of 3.5 it would be $11.55/MMBTU, or about a third the cost of heating with propane.

When rooftop PV is cheaper than grid retail (and it might be already, with subsidies applied) it gets even cheaper to heat with a mini-split. Propane is a commodity, which rises and falls in price with supply & demand. Wind & solar are technology, that only gets steadily cheaper as manufacturing volumes grow (called"learning curve" in economic circles). In the US small scale rooftop PV is already pretty close to grid-retail at levelized lifecycle cost, and it's guaranteed to get cheaper. In Australia where the rooftop PV market is maturing and more competitive it's already less than half the US cost, using the same panels, inverters, and racking systems. The contractors take lower margins, and they have lower advertising & marketing cost, since the customers already understand the product and it's economics. Within the lifecycle of a heating system I fully expect US prices for rooftop PV to be well below what they're paying in Australia today which would be cheaper than your grid retail even without subsidizing the solar.

The effects of ever cheaper wind and solar will have a deflationary effect on electricity pricing, which has already been proven true in states with significant amounts of either, which leads me to think that you will be significantly better off in the coming 10-20 years with heat pumps, even if you don't install the solar on your house, and even if they extend the gas grid to your house.
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20 Oct 2016 01:08 PM
I'm almost positive I have seen both these guys selling it for $15 a sheet. My guess is the price goes up as the temperature goes down. I'll keep an eye on it and wait till spring to see if it gets any cheaper.

I've pretty much settled on Electric as the power source for heating. I just need to pick the delivery method. My wife wants the warm floors, I want the lowest power usage. I have been looking at air to water heat pumps but I'm a little afraid the design work will be over my head.

I've spoken to a couple of the HVAC distributors in the area and they are pushing me away form Mini spits. We get some 2-3 day runs where the temp stays well under zero every year. Sometimes -10 to -15. They're saying the mini split will leave me cold during those times. More homework to do I guess.

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20 Oct 2016 04:03 PM
Air to water heat pumps require more design skills and have an inherent risk.

The cheaper and lower risk way out is to install an electric boiler to heat the floors, but control it with a floor thermostat, then maintain the ambient air temperature with heat pumps. If you set the floor thermostat to a comfortable 72F (and use overnight setbacks) and set the heat pump to 73-74F everybody is happy. The floor system eliminates a cold floor from stratification, but the much higher efficiency heat pump carries the vast bulk of the heat load.

If taking this approach using mini-splits it's worth springing for the wall thermostat. They are a few hundred USD, but it will allow you to set the room temperature more precisely. Wall-coil type mini-splits sense the room temperature by the temperature of the incoming air at the ductless head, which will be different from the average room temperture, and will often vary a bit with outdoor temperature. Without the radiant floor the offset doesn't much matter- if you're too cool, bump it up a couple of degrees with the remote, if too warm bump it down, but don't worry too much about the temperature number that is being displayed. But if you want the bulk of the heat to come from the mini-split rather than the floor you have to be sure that it's setpoint is no lower than the floor's setpoint temperature.

Subzero temperatures are not a problem if you install cold-climate minisplits. Mitsubishi cold climate mini-splits have a specified output at temperatures as low as -13F, and Fujitsu's cool climate mini-splits are fully specified down to -15F. My outdoor design temp is +5F, but it hits negative double-digits in my area at least once every handful of years too (hit -16F this past February during an extended cold snap), and of the people I know heating with Mitsubishis sailed through the cold snaps without complaint. One of those people works in my office, and I specified the equipment for him. I'm sure I would have had hell to pay if his wife was on his case about them keeping up. :-) And that was in a 2x4 framed 1920s antique, nowhere near as efficient as your house.

I know a guy in Quebec who heats his place with four 3/4 ton Fujitsus, in a location that regularly sees -25F temperatures during cold snaps every winter, and sometimes even -30F. According to him when it's -25F outdoors the mini-splits still keep up- the house stays, but the exit air begins to feel pretty tepid rather than the "warm summer breeze" temps they deliver when it's "only" -15F. The output capacity isn't specified in the engineering manuals for when it's below -15F, but it's still putting out significant heat.
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21 Oct 2016 09:11 AM
Good to know the mini splits are still an option.

I will definitely put PEX in the basement slab but I'm thinking I'd like to stick with one heat source upstairs. It would make things simpler and most assuredly cost less. When the basement is finished I will most likely use a drop style ceiling to keep the utilities accessible. If the in slab flooring is heating, the upstairs floors should never be "cold" It might not be "warm" but it should never be cold. At least that's the way I'm going to try and pitch it to the wife :-)

Right now, It's a toss up between the under floor radiant (I keep saying staple up but it would really be an aluminum plate system) and a mini split. I'm leaning towards a ducted model. The second bathroom and the kid's rooms are a little remote. I'm somewhat worried they would stay chilly without heat. Plus if I run the ducting into the rooms I might be able to use them for the ventilation system as well.

Below is a crude, not to scale drawing to give you an idea of the layout we're looking at right now.

http://i450.photobucket.com/albums/qq225/GKG-MO/floor1_zpsjtc0vxau.png

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21 Oct 2016 10:24 AM
It is hard to beat the performance of mini splits. If you also need AC, mini splits become an even more compelling option. However, some people find mini splits to be a drafty eyesore heating approach that can adversely affect furniture placement in an otherwise well designed living space. HR heated floors are extremely comfortable and are not intrusive (i.e., are invisible, quiet, not drafty, and don't affect furniture placement).

In addition to accomplishing a good room-by-room heat loss analysis, one should also accomplish a good return-on-investment (ROI) analysis before selecting a heat source. If you invest in constructing a good building envelope (i.e., a building envelope that will remain well insulated and well sealed for the life of the building) that creates a very low load building, heat source performance has a lesser effect on your monthly operational costs and the ROI breakeven point for the higher performance and typically higher expense heat source options becomes longer and perhaps even non-existent. In short, there is a point of heat source performance ROI diminishing returns just like there is point of insulation R-value ROI diminishing returns.

As such, it is always best to first invest in constructing a good building envelope that is appropriate for your building location/climate. Then accomplish the heat loss and ROI analysis to make a well educated and appropriate heat source selection. I think some folks vastly exceed the ROI point of diminishing returns and will never recover their acquisition costs.
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