I am relatively new here (though I have spent a few months reading much of the forum content) so I hope this post is appropriate.

I am building a new home on my farm in the Fingerlakes region of NY, that my husband and I plan on spending the rest of our lives living in.  Lat 42.7978  unobstructed southern exposure.  The house is 30 ft 5 inches by 46 ft rectangle with a single roof line 5/12 pitch, 2 story on a Frost Protected Shallow Foundation, all 2X6 construction.  The ground floor will be stick built, and serve as an at level basement, but with all the plumbing and electric installed so it can be finished and turned into a one level living area if future needs dictate.  The main living area is the second story, what I call the main floor, and it is a custom built modular under construction at ManorWood Homes in PA.  The 2 biggest driving factors for why I chose this method were 1. cost - the house is going to cost $75.00 a square foot (included the total sq footage of both stories in this calc) with the price including the main floor completely finished with all appliances, furnishings and light fixtures and the ground floor sheetrocked, wired and plumbed, and 2. the contractor I hired to do the ground floor has worked extensively and for many years with the modular folks, and knows modulars extremely well, in addition to having the skills to do all the work without having to subcontract.  I am also doing some of the work, and am knowledgeable enough to be dangerous :o)

All the walls are R21 and the roof is R38, band joist R30.  The windows are all single hung vinyl with heat sealed seams, except for the 2 casement windows which are also vinyl, and one 5050 fixed window.  All are energy star, double pane, argon filled with a U-Value is .32 the SHGC is .31.  The Glass doors on the east side have a U-Value .28, SHGC .32 The Casement windows have a U-Value .31, SHGC .26  I did not have options on the quality of the windows or doors, this is what ManorWood uses.  I am planning on using thermal window covers of some sort.
 
The bathrooms and kitchens are located in the same place on both floors.  All the waterlines are PEX.

The FPSF has 12 inches of compacted slag and crusher run sited on a well drained section of silty clay loam.  We are putting 1 inch of Type IV XPS over a 6 mil moisture barrier, Rebar and wire mat, 1/2 inch Pex on 12 inch centers and will pour 6 inches of 4000 psf concrete.  We are putting 2 inches of Type IV XPS vertically around the perimeter from the top edge of the slab down to 4 feet, with ice and water shield around the top foot and flashing over that.  We are putting one row of 6 inch insulated block around the perimeter on top of the slab to act as a sill.  This area has less that 1500 air freezing index days, closer to 1300

Here are the first couple of things I would like advice on - should I go with 3 inches instead of 2 inches of foam around the perimeter?  Also we are planning on backfilling 4 ft deep against the foam with pea gravel and installing a french drain to daylight - is there something better than pea gravel for the back fill?

The concrete slab floor will be finished and I will probably stain and polish it and maybe install some tile at a future date.  The utility room on the ground floor will also act as a mud room and laundry, with a prep area for the food I grow, and have a small insulated cold room for storage of root vegetable and canned goods. The utility room will also have a dumbwaiter that will go up to the pantry on the main floor.  The radiant is in 4 zones, zones 1-3 with one loop each and zone 4 with 3 loops.

The ground floor has areas for a future bathroom, bedroom, eat in kitchen and sitting room. All the rooms have 8 foot walls.  Though all the walls will be partitioned and sheetrocked they will not be finished at this time, and there will be no sheetrock on the ceilings of the ground floor.  The east wall has the entry door which leads to the staircase to the main floor. We are building the stairs with a 6 inch rise, a landing and turn to make it easier to climb as we age.  The east wall has a casement window over the future kitchen sink, and a 3050 window in that wall.  The south wall has 8 3050 single hung windows in 4 mulled sets of 2 each.  The west wall has one 3052 window, one 2830 window and one 3044 window.  The north wall has an entry door to the utility/mud room - steel energy star half glass and one 3044 window.

The main floor has 8 foot walls and a cathedral ceiling throughout and has a kitchen which opens into a great room (dining and living room area) a library, bathroom and bedroom.  The east wall (the front of the house 30ft5 inch dimension) has a casement window over the kitchen sink, a french door that will lead out to a deck , and a sliding glass door that will lead out to a possible future conservatory on the south east corner of the deck.  The south wall (46 ft dimension) has 8 3050 windows in 4 mulled sets of 2 each, and a 5050 fixed window.  The west wall has 2 3050 windows, one 2632 window, the north wall has one 3050 window.

By going this route I had limited choices as to insulation - the walls are fiberglass, the cathedral roof is blown in cellulose with soffit vents and a ridge vent and baffles that are supposed to create a cool roof to control ice damming.  GAF 30 year roof shingles with ice and water shield, and Quest vinyl siding over house wrapped OSB.  I would have prefered sheathing the outside with foam board under the siding, but did not have that option.  For the ground floor I thought about SIPs, but my contractor does not do SIPs, and I decided I needed someone who could build to meet the requierments of the modular that would sit on it, as a higher priority.  SIPs were also more expensive, though would have been a better energy choice.  I plan on caulking every seam and joint in the ground floor walls before we insulate it, and foaming any entry points.  Are there any other things I should do to prevent air filtration and increase the effectiveness of the insulation?  I am also planning on putting 6 mil plastic over the craft paper of the insulation, so the sheetrock will have the plastic in addition to the kraft paper as a moisture barrier, especially as we aren't going to finish the ground floor sheetrock at this time.  Is this a good idea?  I would appreciate advice on this.

My biggest problem at this point is a heating system.  The house should receive significant solar gain - it is oriented true south - and the slab will provide sufficient thermal mass for the ground floor. I am planning on adding water tubes to the main floor to increase the thermal mass there.  We can not get natural gas, so electric, propane or oil are our back up heat options, all extremely expensive.  I have heated with wood stoves for the last 32 years and would really like to get away from that.  I had considered a wood burning boiler, but just don't feel that the technology is there yet, and really have no desire for huge water storage as needed with a Garn or one of those types of wood fired boilers.  It also gets harder to go out and get in the wood as we age.  I am considering a ground mounted solar thermal system to heat the water for the radiant ground floor, (and to heat DHW) with the ability to add radiators to the main floor if it is not warm enough.  I looked at adding an efficient propane condensing boiler, but if the house actually is as warm as I expect it to be, that would be $2700 dollars worth of boiler sitting around and doing nothing.  Would I be better off with a propane fired on demand hot water heater as back up?  If I ran the heat through the radiant floor all summer, would the ground under the house heat up enough to provide most of the heat during the winter, along with solar gain, and whatever heat the solar thermal panels generate during the winter?  I could cover the ground floor with thick wool carpet during the summer to keep the house from overheating - if that would work.  I have tried to access many of the tools mentioned in the various forums to do a good heat loss calc, but they just don't work with my old Apple puter.  I haven't found one I can use that takes the FPSF into account, though I am sure there must be one out there that will work with OSX 10.3.9.  All and any ideas and suggestions would be much appreciated.  It would be good to make a minimal investment in a heating system and live in the house through the first winter to get a better idea of the reality vs the theory of how well the house gains and retains heat.  It is easy to add more heat, but expensive to buy more system than you need and have it go to waste.

Also, does anyone have recommendations for a solar thermal and voltaic company?  I could probably install a system myself, but would need at least some guidance, if not a full install. Anyone good out here in the Fingerlakes? or Central NY?

I hope this inspires someone with some great ideas for me :o)  Thanks for taking the time to read this and for any ideas and suggestions you might have.

-Rosalinda

Rosalinda,

You really swung for the fences with that post. I don't know if your post was the longest on this site, but its one of the longest I've seen.

If I were you, I would simply spend about $500.00 and get an energywise analysis performed before you build. Go to -> http://www.energywisestructures.com/

They are very knowledgable engineers that can work with you, eventhough you are in New York and they are in Texas. They will even give you a 2 year guarantee on your energy rates.

Good luck....renangle

Best of luck

Unless they have changed, Energy wise does calcs. for Sips and Icf's only.

smartwall,

From what I just read on their website they do SIPS, ICF, and spray foam insulated walls for their tests, though that said, you are right in that it may not help this thread.

renangle

Using concrete floors for radiant heat and solar storage doesn't add up well. Imagine that the floor is propane or wood heated to 80F at 10am and suddenly the sun comes out. You will be opening windows to dump the heat and the floor won't store any solar energy. An active storage system (water tank) is more useful; even non radiant tubed interior passive storage systems only work to the extent you are willing to tolerate temperature swings (for example, are you ok with 80F at times and 60F at others?).

I agree on hiring an expert to do your design.

Hmmm, I thought the thermal mass of the slab and the water tubes were supposed to mitigate the swings in temperature, and that also the insulated area beneath the house would eventually reach a fairly stable temperature that would further stabilize the house temperature.

Actually 80 and 60 would be fine, I currently have my current 1000 sq ft wood stove heated house at about 60 to 65 day and 50 to 55 night. I also can't say I see anything wrong with opening a window and/or using the thermal shades if the house is too hot.

Does anyone exist who has the knowledge and desire to take ALL the variables of thermal mass, solar gain, ground temp and everything else into effect to design a system using solar thermal with some kind of propane backup? Where can I find this expert? Or am I just better off making a SWAG, living in the house through a winter, and then adding what I need to make the house comfortable?

Any advice on the back fill against the perimeter foam? Additional perimeter insulation? Sealing the inside walls of the ground floor? 6 mil plastic under the sheetrock?

Anyone in Central NY (or comparable climate) using solar thermal for radiant heat?

Thanks,
Rosalinda

Rosalinda,

The one thing that seems to stick out to me seems to be the decision to use fiberglass insulation along the perimeter walls and blown cellulous in the ceiling. Why not price using sprayfoam insulation along the perimeter walls (inside) rather than the fiberglass? I believe that is where you will get the most bang for your buck rather than consider using radient heat.

I would look at the technologies that you are considering and see which ones will provide you the quickest return on your investment. It appears that you have done a significant amount of research, so the information should be somewhat readily available.

I would also use hardiboard rather than vinyl outside, as I believe that the increased dollars spent there will not only make the house look a little better, but also have a more attractive resale value.

That is merely my opinion though.

renangle

You have a good sized slab for thermal mass on the ground floor. What is the total square ft of south facing windows? OK I reread it 8 times 15 square feet for windows. The SGHC for the windows is only around 0.31 so you are not going to get a huge amount of solar gain. 8*15*0.31 = 37.2 square feet of solar gain at 100% efficiency.
http://rredc.nrel.gov/solar/pubs/redbook/PDFs/NY.PDF
gives you the solar isolation, I used the numbers for Albany NY. I used the numbers for Flat plate, tilted to 90 deg (like a window).
For Nov- April you have 2.4,2.4,3.1,3.7,3.5,3.1 kwh/m^2/day
So 2.4+2.4+3.1+3.7+3.5+3.1 = 18.2* 30 days(average) = 546 kwh/M^2 /winter. Now to convert 37.2 ft^2 to meters multiply by 0.0929 = 3.45 M^2
So 3.45m^2* 546kwh/m^2/winter = 1887 kwh * 3412 btu/kwh = 6.4 Million btu/ winter of heat gain.
While this is significant, it probably represents ~10-20% of the total heat required for this house.
Are the overhangs designed to shade the windows in the summer? How much obstruction will the overhangs have of the windows in peak summersolar heating time?


I think you should do a few things, I don't know if you can insulate the whole slab if you use a FPSF foundation, but I would if I could 2" XPS would make me happier.

Second, you need to get someone to do Manual J calculations for you to find out what a realistic heat loss for your structure is. You are starting off with code MINIMUM insulation levels and windows in the house, so making passive solar work to provide a significant fraction of your heating in you application will be difficult and more expensive.
I would not use plastic over craft paper as you are creating a double vapor barrier. Use unfaced bats + plastic or better yet craft faced bats with no plastic. Wetspray cellulose would be preferable to fiberglass.

As far as the attic goes, if the trusses can take it, pay to have them blow cellulose to R 50-60 instead of r38

Thank you for the information, it is very helpful.

By buying a modular for the main floor (the thing that made building feasible given my budget), I am very limited in what I was able to change as far as insulation and siding etc. I upgraded the insulation to the maximum offered but had no choice as to what type. I upgraded the siding, but again had very limited choice. Still, doing it this way, despite the limitations, I was able to get the house configuration I wanted (2 story with main story up - will give us great views over the farm and lake) to my own design, light years better than the shack I have been living in the last 32 years.

Eric, won't the main story with the 145 sq ft of windows give me 7.8 million BTU/winter also? I am planning on adding 188 gals of water in solar tubes to the main story for thermal mass to stabilize the temps and solar gain.

The house has a 1 foot overhang all the way around.

Well I have requested a copy of the Manual J book from the library, so hopefully I will be able to get a good figure for heat load. Fortunately cooling has never been a problem here.

Radiant will just cost me the materials as I will install it myself. For a couple of grand I will have a great way to add heat to the house in a clean efficient manner, that can be used with several different water heating systems.

Resale is not an issue as I plan on dying in this house and my heirs will get what they get when they sell the place - not a concern for me. This was also a factor that made modular doable. The place needs to last me approx 35 years. Given an unlimited amount of money I probably would have built Timber Frame with SIPS - maybe in the next life..... I just want to make the most of what I can as far as efficiency and alternative energy, and your help doing that is much appreciated.

-Rosalinda

Rosalinda,

Unless you have a concrete floor, you should be careful as to how you place the solar tubes filled with water.  You could exceed the strength of the floor if the tubes are tall and bunched in a small area.

Alton,
My plan is to use 8 tubes 4 ft tall by 1 foot diam, with a fill of 23.5 gals each. With water weighing 8 pounds per gallon each tube will weight 188 pounds of water and 16 pounds of tube. I am planning on using a weight distribution pad under each tube.and spacing the tubes out along the south wall window areas. The modular has a double band joist all around the outside perimeter, so it should be adequate, but I will be cognizant of the weight distribution.
-Rosalinda

Can you list resource info for the solar water tubes? Hadn't thought of half height ones to get some benefit but not kill the view.

http://www.solar-components.com/tubes.htm

Rosalinda: there are many well-qualified professionals in the Finger Lakes. I suggest you visit the website of the Ithaca Green Building Alliance (IGBA) at www.ithacagreenbuilding.org to review the list of members.

Thanks for the link cnielsen56. I emailed one of their members a month or so ago but never heard back. This time I sent an email to the IGBA, so hopefully someone gets back to me.

-Rosalinda

I am getting ready to install my PEX before we pour the slab. I will keep it pressurized during the pour, but I was wondering what do you all do about all the sharp pointy bits on the rebar, wire ties and 6X6 wire mesh? Since the PEX etc needs to be walked on during the pour, isn't there a high risk of a puncture in the PEX?

For peace of mind I did a probably fairly insane thing, I taped every single pointy bit on the rebar and 6 inch by 6 inch wire mat, before installing my PEX for the radiant floor. The 16 hours it took was probably not necessary, but my PEX did pass the code inspection for holding pressure before and after the pour, so no punctures so far. Now I just have to prevent anyone from drilling into it.

Working with PEX for the first time was interesting, and I had counted on having a second pair of hands to help, but ended up doing it solo. The hardest part was once I carefully unrolled and measured out the lengths I needed - usually around 200 to 250 feet, transferring them to the slab base usually resulted in some re-tensioning and tangling of the loop - what a frustration that was. Adding fittings is a pleasure though and I can see that PEX and I will have a great long term relationship. Since I still haven't figured out what to heat the fluid for the radiant with, I will keep the temporary manifold I made in place.

On to the next challenge.....

-Rosalinda

Rosalinda.
You have put together a complex home and have well. It will probably not meet the 35 year specifications but then that's only my opinion. You appear to know that infiltration is the biggest thief of your heating dollars. Do not make the house completley air tight with out some fresh air exchange to prevent sick house syndrome.
You should be able to get a room by room breakdown of the heating loads (Manual J ) done by your HVAC contractor. Generally HVAC contractors use a rule of thumb or uneducated guess at heating loads and then add 15 to 50% just to make sure. So you buy a bigger unit than you need, this is OK in heating but bad in AC.
It is nice to see some one actually do their homework.
Regards
Joe Redburn
LEED AP
E3 Building Sciences
[email protected]
A suggestion for your DHW is to look into the instant on heaters. I have three of them in my house and love them. Solar hot water is an excellent source with the instant on as a back up.
Solar PV will be coming down in price and should be in your long range plans. Energy cost are due to go through the roof in the next decade.

Progress report: plans VS reality
edited for various reasons

-Rosalinda

Mr. Redburn, thanks for your comments. I am not sure why you said - Quote - It will probably not meet the 35 year specifications - Unquote Do you not think a factory built stick home will last for 35 years? Or are there components that you feel will fail in that time?

I am currently living in a mobile home built in 1960, that I bought used in 1977. I did add a couple of rooms to it, and have managed to keep it patched together to provide a roof over my head for the last 32 years, though it is definitely at the end of its useful life. Since it had a lifespan of 50 years, I would be surprised if I can't get at least 35 out of the modular. There are things I would have done differently if I knew when I started with the mobile home that I know now, such as I should have roofed over the entire structure instead of just parts of it.

I would be very interested in hearing more specifics of why you think it wont last 35 years, as it may give me insight into things that might be changed, improved or done to correct what you see as inherent weaknesses.

-Rosalinda