Can you build a "green" house in the Adirondacks?

[chairrock]

When they installed our Water Furnace, the well driller drilled one 400 foot hole about 10 feet from our house. They installed closed loop plastic pipe with only 20 feet of well casing at the top to protect the pipe from disturbances. They pumped grout into the raw bore, to the bottom, to insure a solid connection between the earth and pipe.I believe they measured 55 degrees.They said it was high!
They hit water at 120 feet.Our water well is about 100 feet from the geothermal well. Our drinking water was cloudy for a few days until everything settled down. We love our system. They upgraded our duct work, etc as a retrofit...Our hot water tank is preheated by waste heat from the furnace. We have never had to supplement heat with our woodstove in 5 years..Finger Lakes....also we have AC now. I don't see how cold weather would effect the systems efficiency with a deep well system. Perhaps with a ground shallow loop... we have 15 acres but all is wood lot except for the front lawn which is also our septic leach field...they drilled the bore in 6 hours....

[montcalm]

When they installed our Water Furnace, the well driller drilled one 400 foot hole about 10 feet from our house. They installed closed loop plastic pipe with only 20 feet of well casing at the top to protect the pipe from disturbances. They pumped grout into the raw bore, to the bottom, to insure a solid connection between the earth and pipe.I believe they measured 55 degrees.They said it was high!
They hit water at 120 feet.Our water well is about 100 feet from the geothermal well. Our drinking water was cloudy for a few days until everything settled down. We love our system. They upgraded our duct work, etc as a retrofit...Our hot water tank is preheated by waste heat from the furnace. We have never had to supplement heat with our woodstove in 5 years..Finger Lakes....also we have AC now. I don't see how cold weather would effect the systems efficiency with a deep well system. Perhaps with a ground shallow loop... we have 15 acres but all is wood lot except for the front lawn which is also our septic leach field...they drilled the bore in 6 hours....

I'd guess it has to do with the effectiveness of the loop in pulling the amount of energy needed in the time you need it.

I was under the impression from a previous post if those requirements can't be met they'll install another loop, but that's extra cost.

[mooregm]

Regarding efficiency with closed units, the efficiency is based on incoming water temperature. That's related to the soil temperature around the loop and ability of the loop to transfer to/from the soil. In November, the incoming temperature will be natural ground temperature -- low 50s. Open loop and closed loop will perform about the same, though closed loop will only approach soil temperature in continued use, not reach it.

As you begin pulling heat from the loop, it draws heat from the surrounding soil, lowering the surrounding soil temperature. During weeks like this one, where we have hit negative outside temperatures on multiple days, the heat pump runs for 12+ hours a day. Our has ran for 24 hours straight jumping between first, second & third stages. In this case, the soil around the loop continues to lower in temperature and instead of returning 52 degree water, it will lower over time to returning 35-45 degrees, and in proportionally smaller loops even lower. The heat pump unit will be sending 20-30 degree water back into the loop. Efficiency is directly proportional to that temperature difference between say 100* fan coil and the entering water temperature.

In a worst-case smaller-sized loop, this effect is the same as with air-sourced heat pumps in cold weather where they cannot deliver rated BTUs, and thus why there are emergency resistance elements in ground sourced heat pumps. In a properly designed ground source system, they are not needed. Both the ground and unit must be able to sustain the necessary BTUs.

On surface loops buried several feet below ground, it's normal for soil to drop 10-15 degrees -- though it will go up/down over the winter based on usage. For drilled loops, the same applies with some pluses and minuses. The largest plus is being in ground water which will transfer heat faster into the adjacent soil, and thus into the loop. The downside is usually having less tubing and the incoming/outgoing adjacent to each other. Above ground temperature does not impact the loop directly -- assuming it is sufficiently buried.

Here is a link to live systems in the Buffalo area from a reputable installer. They show detailed history for several hours and towards the bottom month-by-month. Take a look at them and note the temperatures.

http://buffalogeothermalheating.com/live-systems/

The one I looked at:

http://welserver.com/WEL0713/

Note the annual entering water temperature graph -- water temp from loop entering the heat pump. At -5 months (August) it was in the low 60s from the A/C mode pushing heat into the ground, then come winter lowered to where it is today in the upper 30s.

Another one that is hurting and might be better served with a larger loop. It's down to ~30 degrees: http://welserver.com/WEL0663/

For reference, my 3-ton unit has the following ratings at 30 and 50 degrees:
-- 50 degrees: 34,600BTU output w/ COP=4.58
-- 30 degrees: 26,300BTU output w/ COP=3.81

~24% drop in output means more runtime with at a ~17% drop in efficiency. Efficiency obviously plummets if it gets to the point of turning on resistance backup heat.

[mooregm]

"Another one that is hurting and might be better served with a larger loop. It's down to ~30 degrees: http://welserver.com/WEL0663/"

Actually, looking at that one again, the description says it is two drilled wells along Lake Ontario (read high water table). I'm sure they wanted to do more, but the cost of additional holes vs efficiency needs to be balanced.

[John H Swanson]

I thought U was just the reciprocal of R - but I guess what I've seen there is an assumption where convection and radiation were ignored.

PS. This whole post might be too much information....

As I understand it, U being the reciprocal of R is for outside surface temp to inside surface temp however not outside air temp to inside air temp as there is an insulation effect from the air interface at the outside and inside surfaces. Knowing this theory, I will often laydown if I'm waiting and I'm cold when outside. The complete equation is:

U= 1/((1/ho)+sum of R+(1/hi)) The "i" and "o" are subcripts

hi is the inside film coefficent which assumes still air and is surface orientation dependent.
For wall=1.46 (R=0.68), For ceiling=1.63 (R=0.61), For pitched (catherdral type) ceilings=1.60 (R=0.62); and For floors=1.08 (R=0.92) Though I have seen the ceiling value used for floors. Not sure if that was an error.

ho is the outside film coefficent which is equal to 6 (R=0.17) regardless of the surface orientation for winter heating analysis. It assumes 15 mph wind and a table is used for corrections to different wind speeds as previously mentioned. The ho is 4.0 for summer cooling analysis and it assumes 7.5 mph wind.

So for heating you get R=0.68+0.17=0.85 for free. Don't celebrate too loudly. Perhaps this is why it is sometimes ignored. Except perhaps not in the case of designing winter tents where its doubled. And there are another bunch of equations and table data that come into play depending on the size of the space between the walls and the orientation.

This is TMI: There are different "hi" values if the surfaces are reflective and these amounts depend of the emissivity value. For example the wall coefficient will go from 1.46 to 0.59. So there is a benefit to a foil surfaces. you get and effect of another ~+1R. Only practical if you're in a U or R pissing match.

This comes from the ASHRAE Handbook-Fundamentals. THE standard. My version is 1981. ASHRAE is the American Society of Heating Refrigeration and Air-Conditioning Engineers. The guys who live breathe and eat this stuff. The experts.

[John H Swanson]

- Minimizing surface area is most important. We didn't talk about this, but this seems self evident in that heat flux is the true metric of total loss. Question: calculation of 1 story vs 2 story build.

You pulled me in. I'm going to build that spreadsheet to calculate heat loss for a house. Just heat loss without a heating system analysis. I'm not up for building the solar gain spreadsheet yet but that would show the net heat requirement...

I'll assume one or 2 story structure
Everything will be input cells for flexibility. wall construction, wall area, window area, basement wall construction, roof insulation. I'm not doing cathedral ceilings. Inside layout wont matter much.

Then I'll look at:
2 story 20x30 inside footprint
1 story 20x60 inside footprint
1 story 30x40 inside footprint

While you say heat flux is the true metric of heat loss, I have to disagree. Heat flux (shell heat loss) is a partial consideration. There is also Latent and Sensible heat loss due to infiltration. As I mentioned in an old house design this accounts for up to 50% of the heat loss. Shell losses are important but so is having a tight house.

I'll include the infiltration losses in the spreadsheet

[montcalm]

Here is a link to live systems in the Buffalo area from a reputable installer. They show detailed history for several hours and towards the bottom month-by-month. Take a look at them and note the temperatures.

http://buffalogeothermalheating.com/live-systems/

The one I looked at:

http://welserver.com/WEL0713/

Note the annual entering water temperature graph -- water temp from loop entering the heat pump. At -5 months (August) it was in the low 60s from the A/C mode pushing heat into the ground, then come winter lowered to where it is today in the upper 30s.

Another one that is hurting and might be better served with a larger loop. It's down to ~30 degrees: http://welserver.com/WEL0663/

Looking at the 24 hour data they show, you can see a large effect of this is the effectiveness of the loop as a heat exchanger.



They are pulling down 10* or so just cycling the pump on and off.

When you look at the annual, there is some effect of depletion of the thermal reservoir though.



I wouldn't have thought that to be an issue, especially down at 300-400'. It looks like they are nominally around 50* with no loads.

[montcalm]

You pulled me in. I'm going to build that spreadsheet to calculate heat loss for a house. Just heat loss without a heating system analysis. I'm not up for building the solar gain spreadsheet yet but that would show the net heat requirement...

I'll assume one or 2 story structure
Everything will be input cells for flexibility. wall construction, wall area, window area, basement wall construction, roof insulation. I'm not doing cathedral ceilings. Inside layout wont matter much.

Then I'll look at:
2 story 20x30 inside footprint
1 story 20x60 inside footprint
1 story 30x40 inside footprint

While you say heat flux is the true metric of heat loss, I have to disagree. Heat flux (shell heat loss) is a partial consideration. There is also Latent and Sensible heat loss due to infiltration. As I mentioned in an old house design this accounts for up to 50% of the heat loss. Shell losses are important but so is having a tight house.

I'll include the infiltration losses in the spreadsheet

My nightmares have finally come true and I've been relegated to engineering management. That is, facilitating meetings and floundering technically whilst everyone else does all the work. Only thing I'm missing is that $150k/year paycheck


Right - I'm with you on the infiltration - I guess I had assumed in a bullet further down that would be minimized. I'm willing to do the tedious work of taping seams and spray foaming cracks. If I didn't I would spend the rest of my life thinking of all the things I did wrong and be fantasizing on how to do it better next time.

[John H Swanson]

Well I have the beta version done. I wimped out on the basement as it takes more work and I'll get to that later. I just assumed an outside temperature below the floor for now.

I did what is called a design day evaluation. Where you calculate the heat loss per hour at a select temperature where 99% (or 97.5%) of the time it will be warmer than that temperature. These temperatures are published for many towns, but that is pre-global warming for my data. For instance Plattsburg is -13F and Glens Falls is -11F. I chose -15F for your benefit though its an imput.

I'd have to describe all the construction details but they are largely as I have discussed. I did not reduce windows so they contribute 22% to the total heat loss (considering infiltration) or 40% to the shell loss. I would look to reduce them though you need some for code. Same with 2 doors.

In the end the energy at design conditions was about 18,000-20,000 btu per hour. If you have a 2 story structure, you save 5-10% but you add some more side wall area this way and you might want to add 4 more windows on these walls and that knocks down the savings to about 0.

That said I did not account for wind on the taller building but as we saw that is probably not a factor. Net net, I would build the house you want - one story or 2.

If you have an idea of the size and window sizes, I can input the numbers

[montcalm]

NY code requires all bedrooms to have to points of egress: typically a window and a door. Personally, in my own bedroom I shade them all and only use it for sleeping or watching TV. But I also don't want to be trapped in a fire.


The other day I was thinking about surface area, and if I'm not mistaken, the lowest surface area to volume shape would be a sphere, so that explains why ultra-efficient futuristic homes would use this design i.e. domes. Perhaps not enough benefit to offset the construction difficulty.

Then we'd go to a cylinder, I believe. Again, a PITA to construct, but I know there was a movement at one time to build octagonal homes, and I saw a few built in the 80's. They look really great too. Not sure I'd want the added construction difficulty though. It's surely not enough to offset any efficiency gain or every builder out there would be using them.

So after that, it's a square. This is likely where I'd end up, or slightly rectangular based on layout. Boring, conventional, but easy to build.

So I was then thinking that long and narrow single story is probably most difficult for in terms of heat efficiency, but it's quite great for solar panels. Reference: Earthships.



I'm not going to build an earthship but perhaps a south facing roof at 45* (12:12 pitch) on a single story would be good for solar. Hopefully steep enough to shed heavy snow, but low enough I could use a extension brush to clean off light snow on the panels. I had also thought about having a small access staircase to do this. To me that's one major PITA about solar panels and something I wish there was a better solution for. I've thought of a number of crazy ideas from compressed air to wiper systems, but I doubt any of them would be as effective as good old manual labor.

Maybe even get crazy and do a split pitch roof, something flat and shallow on the north side and steep on the south side.

My guess is though, 45* would be pretty good for our latitude. 60 or so would be best for winter although practically it may not be great in that you'd probably only get a row or two of panels in before it would become prohibitively tall.

[montcalm]

In the end the energy at design conditions was about 18,000-20,000 btu per hour. If you have a 2 story structure, you save 5-10% but you add some more side wall area this way and you might want to add 4 more windows on these walls and that knocks down the savings to about 0.

20k btu/hr is pretty good. That's about 5.7kW. With a COP of a heat pump of 4.6 that's about 1.25 kW power consumption. Not bad for for -15F.

Still be tough to generate enough electricity from solar through the day just to meet that though. And of course night is going to be tough. Perhaps charging the slab throughout the day would be enough to stabilize overnight. I think that'd be a design goal. Maybe use wood during those cold days and use solar to charge the slab for overnight.

For where I'm looking, -15F is not out of the question. It's probably very much in the question. Inlet had overnight/morning temps of -18F yesterday.



Also, I should add, the 20x30 2-story is my current house, minus the small addition. We have (2) 48x72", (6) 30x40" and (9) 28x30" windows. I wouldn't go any smaller than they are, and may not be legal per code as it wouldn't be large enough for a fire escape route. I only have 2 doors in the 20x30 structure - one in the addition, but I wouldn't do this.

A few things I don't like about the two-story design:

- it's really hard to heat evenly upstairs to downstairs. But this may be somewhat a function of poor design - lots of thermal bridging and uninsulated, unheated, unregulated basement.

- I lose at least 80 sq. ft. of floor space to my stairwell (which is a lot in a small house) and probably more functionally.

- solar is up high. Nice for getting above the trees, but not so great for clearing snow.

[John H Swanson]

I've been thinking about it and I changed my mind on the difference of the 2 story vs. 1 story. While its great to see a change of 20%, I once again realize that the energy efficiency game is one of many small improvements. 2-3% each over many design details can add up.

For the analysis, I had reduced the wall thickness to have 2 studs and a 3.5" space between them - 13" overall. Easy to buy and install 3.5" fiberglass batts. I was reluctant with a wall 15" thick. Easy enough to change in the design but I'n not sure if thats where I'd put my money.

I think the important thing is to attack the weakest link or the biggest loss. In this case it would be air leakage, doors, and windows and the floor but the last one is not as would be I had considered. I assumed a single door but with the thick walls one could install a double insulated door - one opening in and one opening out. Like a stom door but a solid core. I just put that into my model and it dropped the design day btus by 344 btus if it was done on both doors.

With regard to the basement, if the floor is well insulated than there will be little heat going to the basement. Fine by me if it's cold but perhaps not if you consider that extra living space. One can always add heat there.

Concerning the house shape, the big advantange to rectangular is that it allows more windows to be positioned on the southern wall so solar gain can be optimized. For efficiency purposes, you want to have utility space on the north wall with as few windows as possible and position most windows on the south side. With a rectangular house you get more window room on the south and a few on the east and west. With a square house, windows are more distributed to the south east and west. Its one of those small differences that give you a few percent - this time with solar gain.

For the roof, yes, it might be good to have a non symetrical pitch roof with a 50 degree tilt angle on the south side and a more shallow one on the north side. If you had a cat walk along the roof line to access brushing the PE panels when snow did not slough, then you could make the mounting of the PE panels such that the bottoms could be moved away from the roof by several inches to lower the tilt angle for the summer months. One ajustment made in March and September. The catwalk could also be an overhang to shade the south windows in summer.

[montcalm]

Some rough solar calcs:

27x44' (golden ratio) single story structure, with 12:12 roof pitch gives about 19' on the hypotenuse without considering overhangs.

Using a 65x43" 330 watt panel, you could fit as many as 40 panels for a 13.2kW system.

Go back in this thread and use my footprint and est. roof angle and I think was at 13 panels for a 4kW system - which would not meet my needs even with NG.

Clearly a single story has this as a huge advantage provided you're willing to trim back trees enough for it to work.

I had also consider single story to be superior in your "free" thermal mass storage. Obviously not free as pouring and building a foundation with a larger area is going to cost significantly more, but the amount of storage is doubled.

[montcalm]

This is supposedly a 1200 sq. ft. layout. I think it's 20x60'. It won't quite meet code here, but I think that's easy to fix. Add a door in the dining room (bedrooms apparently only need one window or an exterior door). I'd probably shuffle that laundry room around, make another small office/bedroom and split the closet on the master and existing bedroom. And a stairwell into the basement.

But if the top side were south facing, this would be an ideal solar layout. Maybe just do some small windows in the bathrooms for some natural light. Maybe one in the kitchen.

This can only do 32-33 panels on a symmetric 12:12 roof. Perhaps a design like this that is this narrow should move to a shed-type roof?

[John H Swanson]

This is supposedly a 1200 sq. ft. layout. I think it's 20x60'. It won't quite meet code here, but I think that's easy to fix. Add a door in the dining room (bedrooms apparently only need one window or an exterior door). I'd probably shuffle that laundry room around, make another small office/bedroom and split the closet on the master and existing bedroom. And a stairwell into the basement.

But if the top side were south facing, this would be an ideal solar layout. Maybe just do some small windows in the bathrooms for some natural light. Maybe one in the kitchen.

This can only do 32-33 panels on a symmetric 12:12 roof. Perhaps a design like this that is this narrow should move to a shed-type roof?

If it weren't for a passion for this stuff I'd be thinking about asking a fee.
Let me see what I can do to evaluate it....