Net Zero (house and two cars) in Minnesota

Discussion in 'Environmental Discussion' started by Zythryn, Nov 9, 2015.

  1. Trollbait

    Trollbait It's a D&D thing

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  2. Mendel Leisk

    Mendel Leisk Lapsed Cargo Cultist

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  3. Zythryn

    Zythryn Senior Member

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    Lensovet had sent me a few questions which he gave me permission to respond to here (as I figured some others might be interested in as well).

    In order:

    The walkway between the garage and house is there for a few reasons.
    First, it allows us some distance between the house and garage to cut down on the amount of shading we get on the solar panels on the garage roof.
    Second, it unseated, but insulated, so we decided to use it as a type of 'mudroom'. We added a gardening workstation there as well.
    This allows us to maintain a more efficient shape for the heated part of the house.

    Tile over hardwood? We chose porcelain tile mainly due to the thermal mass and the fact it will transfer the heat from infloor radiant tubing much better than wood.
    Lower maintenance and easier to clean were also big factors in the "pros" column.

    Not sure I understand the siding question? What else would you use?
    The siding acts as the first layer of protection against the elements. This may also be a regional thing. Here in the Midwest, anything other than siding is pretty uncommon.
    There are a few houses with brick facades, a few stucco houses. In both cases, they tend to not stand up to the freeze/thaw cycles as well and frankly, I just don't like the looks or expense.

    The steel roof will outlast any asphalt shingles, perform better and is 100% recyclable. It also stands up better to our weather than slate tiled roofs used in other parts of the country.

    Tesla's solar roof? I love the concept, but want to see the details. "Solar Shingles" have been around a while. Their efficiency has always been rather poor.
    Regardless though, we already have our solar panels in place, so it isn't anything I am planning to do until they need replacing in 30 years or so.

    The three car garage is a bit of a luxury. We probably would have done a 2 car garage if it were not for the fact that we needed more roof space for panels ;)
    That said, having room for both cars and storage is really nice.

    The landscaping was awesome. The most difficult task was probably the boulder wall which is detailed in the blog.
    We went with all local plants, four rain gardens with overflow from the first to second in each pair.
    We have a little bit of turf and no irrigation system. The turf is a variety of tall fescue that should require no watering.
    Once the plants are established, they should require no watering except maybe in the worst of drought conditions.

    The lot is about 125'x125'
    The house is 2437 sq' total (that doesn't include the garage).
    Upstairs alone is just shy of 1300sq' although the basement is a used daily and really is part of our home, so I don't quite understand the exclusion (many people do this, I am not singling you out).
     
  4. Mendel Leisk

    Mendel Leisk Lapsed Cargo Cultist

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    Good point about steel roof, being recyclable. Asphalt shingles are probably 100% NON recyclable?
     
  5. fuzzy1

    fuzzy1 Senior Member

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    Another advantage of standing seam steel roofs is that solar panels and racks can be mounted with no roof penetrations to eventually fail and leak. All the hardware is bolted to clamps on the seams. Wiring goes into conduits that drop over the end and down the siding, not through the roof into the attic.
     
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  6. Zythryn

    Zythryn Senior Member

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    Excellent point, which was also part of our thinking.
     
  7. lensovet

    lensovet Not your typical youngin :)/BP Brigade 207

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    Yep, in California I think siding is a rarity. In NJ i would say most houses have siding but stucco and brick are quite common as well. Feels like a less recyclable or stable material. What's the life expectancy on it?

    I completely get the basement being used daily and that is my ideal home as well. However I have never understood whether home sellers include this square footage or not and was just curious about the "primary" living space (kitchen/dining areas/living/sleeping areas) in thinking what's an "appropriate" square footage. 1300 sq ft is actually less than I expected so I'm glad to see that it still works.

    Can you share more about the heat pump? How many wells were drilled, is the system open or closed, air vs. water, and what kind of heat pump you got? Are you doing hot water cogeneration for it as well? And how exactly are you heating your water since you don't have natural gas?
     
  8. Zythryn

    Zythryn Senior Member

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    The Hardi-Board has a 30 year warrantee and is engineered differently for different climate zones.

    We do plan to be able to live on the main floor when we can't handle stairs anymore.
    The only thing that would have to be upstairs if we built 'on slab' would have been the mechanical room.
    Otherwise we have an exercise room, and music corner and my dream game room.
    If we need it, we can convert downstairs into an apartment, complete with kitchenette, its own entry and bedroom.

    I have a blog entry that mentions a lot of that at Category: GeoThermal - Driven to Net Zero
    Basically, 14 100 foot deep wells in a geo thermal, closed system.

    We use GeoComfort heat pumps. One for the radiant heat and one for our domestic hot water.

    Dinner time, but I would be happy to go into more detail later...
     
  9. Zythryn

    Zythryn Senior Member

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    We now been in the house for 4 months, with three full months of detailed data.
    I have a blog entry up with all sorts of charts (yes, I am a data geek).
    Ever try to lose weight without using a scale? - Driven to Net Zero


    Between October 1st and December 31st we are net positive. We generated about 230kWh more than we used in that time period.
    I expect we will chew through the rest of that by the end of January, depending upon how sunny it is.

    I also estimated we would drive about 8000 fewer miles on our cars each year, due to moving closer to the city center.
    It looks like I underestimated. Now, I am thinking it is closer to 14,000 fewer miles.
    If that holds up, we may be have a sizable surplus at the end of our first year:cool:
     
  10. Zythryn

    Zythryn Senior Member

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    Our first winter was a great success.
    The heating was more than adequate with just the heat pump as well as very comfortable.

    Overal, from Oct 1sr to April 1st our entire house (including two electric cars) used just under 8000 kWh. Our modeling software calculated we would use about 11,500 kWh.

    We have just over 1,000 kWh surplus coming out of winter. Net Zero for the year looks to be 'in the bag' (y)

    Our first winter is in the books! - Driven to Net Zero
     
  11. tochatihu

    tochatihu Senior Member

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    Zythryn gets well-deserved respect here for 'doing it' and telling us about it. I would also mention one accumulator website for performance of commercial and residential renewable energy:

    PVOutput

    If this thread piracy is not ill-received, perhaps others will link to additional websites they know about.

    Fans of graphical data will not be disappointed by pvoutput. You know who you are :)
     
  12. Zythryn

    Zythryn Senior Member

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    We had a pleasant surprise today.
    Geo Comfort, the manufacturer of our Geo thermal system, made a video a month or so ago.
    They just released it!


    In short, and to update it, in the almost 10 months living here, we have found that the house is not only extremely energy efficient.
    We also have found ourselves healthier, with more free time, and driving less than we used to.

    Another update. With just over three months to go until recording of data started, we have a surplus of 4400 kWhs. AC is using a bit more energy now than in May, but much less than heating did.
     
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  13. Zythryn

    Zythryn Senior Member

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    We just got word that our LEED certification came through.
    Out home reached LEED Platinum!
    We had earlier received Green Star + certification as well as Energy Star Home.

    We have one certification left that we are waiting for. It is called Living Building Challenge. Part of that certification requires a full year's data. That full year will be complete October 1st.
     
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  14. iplug

    iplug Senior Member

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    Did you upgrade to your heat pump water heater from a natural gas or electric resistance heater? What specs and how much energy use (kWh) annually before and after, if you have this data?

    We're probably going to change our natural gas water heater in the next couple years for an air sourced heat pump one. Current water heater is 15 years old.
     
  15. iplug

    iplug Senior Member

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    @Zythryn, do you clear snow from your solar panels in the winter?
     
  16. Zythryn

    Zythryn Senior Member

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    I have, but not all the time.
    When I do, I get the lower one or two rows. The top slides off or melts pretty quick after that.
    We have optimizers on each panel such that each panel will still produce some power even if it is partially covered.
     
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  17. iplug

    iplug Senior Member

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    @Zythryn, what service panel size do you have?

    Like most homes built in recent years, ours came with the 200 Amp standard. After a couple vehicle charging stations, in the process of switching out a gas water heater to a heat pump, existing pool pumps, spa, electric clothes dryer, electric ovens, AC, etc, it looks like any more electrical upgrades would require a larger panel ampacity for us.

    Part of our issue is the service panel’s main bus capacity rating. We installed solar panels a few years ago and added more earlier this year taking us up to ~11.5kW. Also, when the price is right, we would likely add a home battery storage solution. Since electricity would flow bi-directionally, this would potentially require a higher amperage service panel for reasons of peak shaving electricity received and electricity delivered back through the bus.

    With your geothermal system, vehicle charging stations, and plan on installing three Tesla Powerwalls soon, have you been able to hold at 200 Amp service?
     
    #37 iplug, Oct 8, 2017
    Last edited: Oct 8, 2017
  18. Zythryn

    Zythryn Senior Member

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    We now have a full year of energy data and it’s now official we are living in a net zero energy house:D:ROFLMAO:
    At the end of twelve months, we have produced 9,000 more kWh than we used:eek:


    • We produced 5% more than modeled.
    • Last winter was warmer than the 1980-2010 average (I expect this to happen more often than not)
    • We drove a LOT less than we had predicted
    The biggest single factor was the cars. We used over 4000kWh less than we had anticipated.

    We have two 200Amp panels. We have 300A Service to the house, but wanted lots of extra room on the panels.
    We have a 100A subpanel in the garage for the car chargers and normal garage stuff.
     
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  19. lensovet

    lensovet Not your typical youngin :)/BP Brigade 207

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    Wait how does this work, two 200A panels + a 100A panel = 300A? lol
     
  20. Zythryn

    Zythryn Senior Member

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    The 100A panel is a sub panel of one of the 200A panels.
    We had this setup at our old house. It makes expansion much easier in the future.
     
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