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Several questions about building green (ICF, cold Canadian weather, solar panels, etc)

C_Wolf | Posted in General Questions on

Just had a few questions related to green building, and I hope someone can help me out with answering my concerns below. Hope to learn as much as I can so I can eventually construct a green building! 

EDIT: This is a building I want to construct on an acreage of about 5-10 acres of land, so there would be no city water etc.  

(New construction idea I plan on building in future)

1. I like the idea of building a concrete home (ICF potentially), but the temperatures where I live concern me if it is possible to build in concrete while still maintaining decent R-value for ceiling and walls.

2. I would also like to go with a geothermal heat pump system that gives off radiant heat (pre-placed inside of concrete floor slabs).

3. The design I have come up with has a basement finished with rooms, main floor, second floor, and a roof accessed by stairs (the roof would be flat). 

Additionally, there is a two car garage attached, but nothing is above or below it in terms of main housing design.

4. The main portions of the roof would be for solar panels, and for summer time use I want to have the ability to have multiple long rectangular planter box’s up there for vegetables, but also the ability to have a nice quiet area for soaking up some sun. There is something about being elevated and in a quiet space that feels great. In addition to the planting, I would also like to have this area for bonsai plants I keep, and it is best to keep them outside away from wild life. 

5. The basement floor plan is 1023 sq ft, whereas the main floor plan is 1155 sq ft, the second floor, and the roof follow the same sq ft as the main floor 1155 sq ft. The garage is 24 ft by 24 ft 

Some of my concerns:
1. Sufficient insulation from ICF or other concrete alternatives with building. I hope to attain a R-value high enough to be sufficient for the weather I live in for half of the year (winter). The weather here can be quite severe or mild at times during winter, on average the weather is around -20 Celsius or so here, while as the more severe days would be -30 Celsius to -40 Celsius.

2. Can geothermal heat pumps be used to heat radiantly?

3. How effective would solar panels be during a Canadian winter? I think there is a way to calculate grey days, and determine how many panels you would need or estimate, but still curious should a person still hook up to main electricity for back up situations or just go completely green pure panels? I think having a back up is always a great plan especially in my climate where it is kind of essential.

4. I don’t plan on building this myself, but I do like the design I have. How does one go about constructing a green building of this style? Do I contact an architect and have them make official plans based off of my design I presented? Or what route would be best? 

5. Another concern I have is finding someone with experience who understands how to build with ICF (if I used that), or finding someone in general who understands about green building. 

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Replies

  1. Expert Member
    Dana Dorsett | | #1

    Is -20C the hourly mean temperature for weeks at a time, or is that the typical daily low for weeks?

    ICFs can be had with fairly substantial R-values, some with 5" or more of EPS on each side. How much were you looking for?

    There are code specifications for building with concrete that need to be adhered to. An architect or engineer is usually going to have a better idea on how to specify the type of concrete and reinforcement, footings etc needed than someone who has never done it.

    Yes, ground source heat pumps are quite often used for low-temperature hydronic heating such as radiant slabs.

    The effectiveness of solar PV in winter depends on your latitude, shading and local winter cloud cover, but there are weather databases that track historical weather and cloud cover averages going back decades for many locations in Canada. The average performance can be predicted, but with year on year variation. If you have reasonably close access to a power grid it's usually cheaper to hook up to the grid rather than buy a barn-full of battery to monitor & maintain. The types of equipment for controlling the PV array is substantially different between a grid-tied system and a battery system, so this is an important decision to work out the details on ahead of time.

    There is no such thing as "...completely green pure panels...".

    In general hooking up to the grid uses quite a bit less metal & material than off-grid systems with batteries, but if it's a kilometer or more from the house to the grid, off grid might still be lower impact.

  2. Trevor Lambert | | #2

    I personally don't think an ICF home can be considered "green". Of all the possible building materials, foam and concrete are near the top of the "worst" list when it comes to carbon foot print and other environmental effects. You almost have to use some amount of one or the other, or both, but selecting a design which maximizes both is not a green building. It's not inexpensive either.

  3. C_Wolf | | #3

    Hi Dana Dorsett,

    Thanks for replying back! Yeah, during winter season (4-6 months of the year) it slowly declines in temperature where the middle section for 2 months of that period is where it is mostly the worst. On average around -20 Celsius I would say, but depending on weather could be lower as well up to -40 Celsius if it is a bad storm.

    I'm uncertain about how much EPS on each side I would need, but I'd like to have r-values that relate to the area I'm in. I'm unsure of what values that would be maybe 20-30 r-value for exterior walls, and 60 r-value for roof or higher if possible. Again I'm not an expert at what would be required for these types of climates, but whatever is best suited is what I would wish to have.

  4. Expert Member
    Dana Dorsett | | #4

    A more specific location rather than some random temperatures could be useful for assessing what is best suited. That would help figure out the solar uptake too.

    2.5" + 2.5" EPS (= R21) is the thinnest offerings from some ICF vendors. That's not a very high R-value for locations where the hourly binned mean temperature is -20C over couple of months out of the year, such as Fort Severn ON.

    https://weatherspark.com/m/146534/1/Average-Weather-in-January-at-Fort-Severn-Airport-Canada

    Trevor's point is valid- there is a lot of greenhouse gas emissions in the making of concrete. Unless needed for structural capacity (any hurricanes coming your way?) there are lower-impact construction methods. And polystyrene insulation isn't exactly the most environmentally friendly insulating material either, but it's fairly impervious to frost/ice and has appropriate uses in arctic zones.

  5. Ethan Foley | | #5

    Where are you located? In Ontario where I design houses ~R-20 (effective) walls and R-60 ceiling is code-minimum.
    We recently did work on an existing off-grid house that had a new owner. The new owner had to run a generator VERY often, so we eventually decided the most economical solution was to connect him the the grid. And that cost $30,000! It get's pretty expensive to go off-grid in cold cloudy climates, and you have to be willing to live a certain lifestyle. I would advise connecting to the grid.

    ICF is a great product but not very "green", as Trevor noted. There are "greener" and cheaper methods for building if you are interested in using something other than concrete.

    Your building inspector will require a set of construction drawings before you get a permit, so take your design to a design firm with good knowledge of energy efficient building principles, otherwise you'll end up with a set of plans for a code minimum house or a set of plans with no details for unusual high performance details.

  6. GBA Editor
    Martin Holladay | | #6

    C. Wolf,
    You can't operate a ground-source heat pump ("geothermal") system from an off-grid electrical system in Canada. For more information, see "How to Design an Off-Grid House."

    If you want to live off-grid, your heating options are (a) a wood stove, or (b) a propane-fueled space heater with a through-the-wall vent.

  7. C_Wolf | | #7

    @Trevor Lambert,
    Thanks for getting back to me. True, there is better materials of course, but I live in an area where high winds with the potential of tornadoes can and do develop quite often. For that reason I feel like if I were to build a traditional wood framed house, and a tornado were to come (high unlikely, but I like to take into consideration these risks and scenarios because the environment is important to me even if the risk is low) and knock down or flatten my wood framed house, then I would essentially have several options ahead of me. 1. To move into an apartment, or buy another house in the city etc which would likely be a wood house as well, or rebuild another wood house / concrete house. If I were to build another wood house, then you can imagine that 1st house + 2nd house is a higher rate of labor and energy put into a house than building one concrete house. I do understand that initially the energy consumption required to build a concrete house is more than that of a wood framed house, but our environment is in a delicate state, and I can't take the risk of a fire burning down my house / tornado knocking it down just to be required to rebuild in the end essentially doubling my carbon footprint. Not to mention all of the fossil fuels being burned and put into the air if a fire was to occur likely makes it higher than double.

    @Dana Dorsett
    Hi again, thanks for getting back to me. I live in the province of Manitoba which is central of Canada you could say, and we experience some of the coldest temperatures out of most of Canada. This location is just north of the border (1 hour driving distance). This location would be similarly close to Minot or Grand Forks in USA, around 2-3 hours more north.

    @Yupster
    Manitoba province, about 1 hour north of the USA / Canadian border. Maybe I will consider connecting to the grid after all thanks for your input.

    So I should potentially go with 4" to 5" EPS on each side of the concrete to maximize r-value of exterior walls?

    @Martin Holladay
    Ahh thanks that is good to know! I guess I will be hooking up to the grid then, but I would still like to have some kind of backup way of providing heat to the building that excludes the requirement of being connected to the grid, and that isn't related to burning fossil fuels. Perhaps one way could be solar panels storing energy into batteries, and I could use those batteries to heat via an alternative source such as an electric element that is connected to the closed loop system of the house which heats the water / anti freeze supply to act as a temporary measure. I like a backup system simply because if the power goes out in winter it's not a good day. Is there any alternative way I could at least provide heat, or both heat and power to the building as a backup system?

    Thanks everybody for your input it is really valuable!

  8. Expert Member
    Peter Yost | | #8

    The most egregious component of concrete from an environmental perspective is the Portland cement. If you type in "Portland cement" in the GBA search bar, there are quite a few resources on the impact of this concrete component and alternatives.

    The biggest issue usually is getting a local ready mix plant to consider substitutes for Portland cement.

    Peter

  9. GBA Editor
    Martin Holladay | | #9

    C. Wolf,
    You wrote, "Perhaps one way could be solar panels storing energy into batteries, and I could use those batteries to heat via an alternative source such as an electric element that is connected to the closed loop system of the house which heats the water / anti freeze supply to act as a temporary measure."

    This is entirely unrealistic. At best, house batteries can supply about 3 days worth of electricity -- and that will only happen if you have no electric resistance heating appliances like electric stoves, toasters, hair dryers, or electric heaters. Even a minisplit heat pump won't work -- it might operate for 10 hours or so on a large battery.

    Here in Vermont, I can get 15 or 30 cloudy days in a row in November and December. Solar panels and batteries won't get me through -- even if the batteries have nothing to do with the heating system.

    In your case, if you are worried about power interruptions, use your wood stove.

  10. Jon R | | #10

    C_Wolf: You can review this for a guy who heats his off-grid Canadian house with PV solar. Small house, lots of insulation and thermal storage. While a heat pump would be thermally more efficient, he found resistance heat to be more cost effective. It's not clear to me if he ever uses fossil fuel backup (probably does).

    Using very large water tanks, one could go 2 weeks without significant power.

    http://electrodacus.com/DMPPT450/dmppt-presentation-v01.pdf

    1. GBA Editor
      Martin Holladay | | #11

      Jon,
      It's not clear from this PowerPoint presentation what this is about, but it sounds as if this is pencil-and-paper math -- not data from a completed house. I'd like to see a post-construction report that includes (a) actual construction costs, (b) 12 months of monitoring data.

      Absent that, count me a skeptic.

      1. Jon R | | #14

        From other sources: he has the house and lives in it. His thermal storage is reported to be good for 3 days (not much).

        I agree - more data needed. And it (offgrid with no fossil fuel use) won't make sense on a green or cost basis.

      2. Expert Member
        Dana Dorsett | | #15

        It would probably help his presentation if he were a native English speaker (I think he's Slovak, or Czech).

        His technology is a really basic DC power optimizer for the PV, which isn't a radical idea. DC power optimizers are standard fare in both grid tied and battery PV systems- he's just using it for thermal storage of the energy output rather than battery charge controllers or inverters. Storing the energy as heat in the thermal mass of the house is a bit more out of the ordinary, but doesn't violate the laws of physics.

        With enough panel you can do a lot even at 15% efficiency, and panels are getting cheaper faster than the rest of the components that make up PV solar power system. With fewer energy conversions the net efficiency can be quite good, and the cost of the equipment pretty low, but the flexibility of use leaves something to be desired. Most people would need or want adequate backup. (Wood stoves are pretty reliable, lo-tech, and work under all weather conditions.)

        From a cost, reliability, and longevity/lifecycle point of view it probably beats getting the heat out of ground source heat pumps for an off-grid system if you do both the load math and financial math. The control electronics (which he sells) and wire (for the embedded resistors) are pretty cheap and rugged. But this is definitely not for the average off-gridder doing their first house & heating system.

  11. Trevor Lambert | | #12

    There may be good reasons for building an ICF house, it's just that being green isn't one of them. I wouldn't have even commented if you hadn't referred to it a couple of times as green building.

    That said, I think your fear of complete annihilation of a wood-structure house is somewhat irrational, given the likelihood of it happening. If you applied the same level of caution to everything, you'd probably never leave your house. Note also that while an ICF house is very likely more tornado resistant, it's far from tornado proof. F4 and F5 tornadoes will knock down concrete buildings. F2 and lower probably won't destroy either an ICF or reinforced wooden house, which account for 95% of the tornadoes that land in Canada. An F2 will typically damage siding and rip shingles off the roof.

  12. flyingdutch | | #13

    C_Wolf: Being in the weather business, and reading all of the responses above (and also being a Canadian), I have to ask.......are you located in Elie, Manitoba? It may explain your tornado concerns....

    https://en.wikipedia.org/wiki/2007_Elie,_Manitoba_tornado

    Cheers Paul

  13. Lance Peters | | #16

    C_Wolf, I urge you to watch the APA webinar "After the Storm". This is a data-backed overview of tornado characteristics as well as a lengthy and thorough set of forensic investigations into wood framed structure damage from high wind events:

    https://www.apawood.org/after-the-storm

    It's important to set realistic expectations for the survivability of your future home. You could build an ICF house that has extremely strong walls, but if windows and doors are compromised by flying debris and the structure is pressurized, the roof can still lift off resulting in near complete destruction of the home anyway.

    Going beyond what's covered in that webinar, there are a full compliment of structural products available that go above and beyond their common building recommendations to tie structural members together and anchor them to the foundation. A well detailed wood framed house with some thoughtful wind resistance features can be very resilient in a storm.

    As others have pointed out, ICF construction is not "green". The two main ingredients are concrete and foam, both of which carry a high environmental impact.

    Another issue with ICF is the value. It costs a lot more to build with ICF, and while that approach usually leads to a well air-sealed structure (a good thing), the R-value of the structure is very low considering the cost. Several ICF companies I've seen promote their wall systems as performing FAR above their actual insulation value, one even claimed their R-20 walls performed at R-40 levels. That's simply untrue and misleading.

    ICF construction also has a lot of thermal bridging built in where floors meet walls. The inside layer of insulation is compromised at these locations and the effective R-value is cut in half (if inside and outside foam layers are the same thickness). If you have concrete floors which are highly thermally conductive, a lot of heat is lost. Adding foam thickness to the outside of the structure can reduce this effect, but that can add considerable cost.

    I got two quotes for an ICF foundation for our house and both quotes were roughly 45% higher than the cost of a simple poured foundation. Given that for an ICF foundation, the outboard insulation isn't doing much insulating below grade (the concrete core is thermally connected to the cold footings), there was no added value in ICF from my point of view.

    As far as your energy goals go, you'll need accurate solar insolation data for your area. Also, a good read on solar panel performance in Canadian winters is the Northern Alberta Institute of Technology (NAIT) study:

    https://drive.google.com/file/d/0B8iovcGawVd-Ri02Q090Y29Xbzg/view

    Spoiler: if you plan to depend on solar panels in winter, you better plan to clean them off. You also better plan to have a LOT of panels. You may want to get some help designing your system, and the system will depend on the thermal performance of your home's envelope so that will need to be a part of the plan.

    1. Lance Peters | | #17

      Here's a nice video pointing out some of the fastening strategies available to resist high wind loads:

      https://www.youtube.com/watch?v=o-PMi23aQ3k

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