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Passive houses, you can heat them with a hair dryer

Post in 'The Green Room' started by begreen, Nov 8, 2013.

  1. begreen

    begreen Mooderator Staff Member

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  2. Frozen Canuck

    Frozen Canuck Minister of Fire

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    Yes we keep advancing as an industry. Next step insert people & a ventilation system & done. Need a small heating system in some locations (here) when the house is empty. Nice to see after all these years of stick framed bang them together boxes that fill every suburb. The best of these squeeze out every available BTU before venting & replacing with fresh air, even waste water heat recovery. In your location BG a hair dryer may be over kill for most of the year.
    The kids are really what is driving this, they want nothing to do with Mom & Dad's suburbia or the energy waste that comes with it.
  3. peakbagger

    peakbagger Minister of Fire

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    There are some arguments out there that passive haus's are overkill. I.E. the extra cost to build them is not worth the savings. In my area they are the province of architects and high end builders and are built for "snob" appeal and require ideal sites that are pretty rare. Nothing wrong with the concept but I figure, installing a few more PVs and net metering so I can run a heat pump and a couple of cords for real cold weather with a smaller more cost effective house is the way to go but I realize that I am stating an unpopular concept.
  4. stoveguy2esw

    stoveguy2esw Minister of Fire

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    only thing that would worry me with that type of structure is the potential for what you call a "sick" house where no cross ventilation can allow germs and such to linger, as well as moisture.

    full disclosure; i really havent studied up on this so they may have developed ways to combat this
  5. Jags

    Jags Moderate Moderator Staff Member

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    Is anybody aware of a passive house floor plan that isn't two or more stories? Going forward, I will not own another two story home.
    PapaDave likes this.
  6. Seasoned Oak

    Seasoned Oak Minister of Fire

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    Sure beats going broke paying heating bills. Around this area there are still homes with ZERO insulation,old leaky doors,windows.They are Barely slowing down the wind Different reasons for all of it. Some dont know better,some are rentals,some get their heat free from the Govt.
  7. peakbagger

    peakbagger Minister of Fire

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    Is anybody aware of a passive house floor plan that isn't two or more stories?
    Highly unlikely, optimal house design is to try to get as close as possible to a dome to minimize exterior surface area and a two story will have far less surface area per interior volume than a one story . There are also some nice passive ventilation options that work with two stories that don't work well with a one story. Of course improperly designed passive solar homes from years back are infamous for roasting their owners out of the second floor during the day time.
  8. Jags

    Jags Moderate Moderator Staff Member

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    Hence every old farm house being two story. Yeah, I get why it is done. I am sure a ranch home can incorporate some of the passive tech and then throw some PV at it and you will end up with close to the same outcome, I guess.
  9. begreen

    begreen Mooderator Staff Member

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    You could do a pretty well insulated single-story house. Its energy footprint could be quite low, particularly if it doesn't have to be too large.
  10. woodgeek

    woodgeek Minister of Fire

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    All such houses come with mechanical ventilation and a heat exchanger for 24/7 fresh air at a predetermined rate. In contrast a standard house will be overventilated 80% of the time, and underventilated 10% of the time (when the temp diff in/out is near zero).
  11. DickRussell

    DickRussell Member

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    True, some advocates of building much better houses than in the past argue that the Passive House requirements are overkill for much of the USA. Some builders in the Portland, ME area got together and came up with a set of guidelines for the "PGH" (Pretty Good House), which puts you into the realm of superinsulation and reasonably tight construction (better than even Energy Star Version 3), without going overboard on the specs.

    Passive House requirements call for a blower door test giving no more than 0.6 ACH at the standard 50 pascals depressurization. Actually, anything below 1.0 to 1.5 is quite good, and in climate zone 6 (much of New England) Energy Star Version 3 allows up to 3.0, if I've got it correctly. Either way, you cut heat loss by doing all you reasonably can to tighten up the house at construction time. But then you really need to provide mechanical ventilation both to provide fresh air for the occupants and to keep the humidity down (yes, even in the dead of winter with bone-dry air outside). There are standards from ASHRAE and a newer alternate standard from Building Science Corporation spelling out how much ventilation air is appropriate. And of course to cut the heat loss due to ventilation, the incoming and outgoing air exchange heat in a heat exchanger (HRV, or heat recovery ventilator). There is just no justification anymore for claiming "the house can't be too tight - it has to breathe." The occupants have to breathe. The house has to avoid moisture accumulation issues.

    With a superinsulated house, if you like heat from a wood stove, the unit required is much smaller than for an "ordinary" (leaky) house, because the house just doesn't leak heat anywhere near as fast. Then it makes sense to provide combustion air with a directly connected outside air kit (OAK), about which there have been threads on this forum.
    Floydian and Laszlo like this.
  12. woodgeek

    woodgeek Minister of Fire

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    Not unpopular. In the states, there is more of a bias towards envelopes with maybe 2x the heat load of a passive house (still 60% less than current best 'code', but not 80% lower) along with a big PV array to get to net zero. Pencils out cheaper than a passiv haus with a smaller array, and both are net-zero. The concept is called by many the 'pretty good house':

    http://www.greenbuildingadvisor.com...og/pretty-good-house-better-building-standard
    Floydian likes this.
  13. DevilsBrew

    DevilsBrew Minister of Fire

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    Honestly, I'm burned out from the exaggerated claims of the media and those based in the NW. Maybe I'm a green realist. A hair dryer? Seriously? Stick the house in Cleveland or Buffalo and prove that it can be heated with a hair dryer. Go for it. :)
    wazzu likes this.
  14. begreen

    begreen Mooderator Staff Member

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    Nothing exaggerated about the facts. The Pac NW climate is similar to England and parts of France. In some New England places I would think the goal would be easier to achieve with more sunny days than here.
  15. Frozen Canuck

    Frozen Canuck Minister of Fire

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    Actually we are getting close to that up here. Several builders regularly getting under 10 btu/sq ft. Holy grail for this area is likely 5 btu/sq ft. So at those energy consumption rates, once you factor in all of the residual heat of actually living in a structure cooking, bathing etc. Well you are really close & thats up here. So in the PNW sure, totally doable.

    Believe me I am/was one of the biggest sceptics when it comes to this & the claims that followed...but it does pencil out. I know this as we have built a few up here, sort of trials & learning opportunities, learned a pile from those involved, daily jobsite meetings with all crews by architect & engineers, plenty of conversation about the minutia of each aspect of building.

    Actually when you look at it all, in many situations they could be considered a tad conservative with their figures.
  16. DevilsBrew

    DevilsBrew Minister of Fire

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    The average amount of sunshine in NW Ohio, Western PA, and Upstate NY equals or is less than many places in the PNW. Add to that the temps. Winter lows in Seattle average in the 30s. That is toasty.
  17. begreen

    begreen Mooderator Staff Member

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    Look at Dec and Jan averages and I think you will find the NE ahead for sunshine. As Frozen Canuck pointed out, construction techniques have progressed to the point where this is a moot point.

    FWIW my BIL heats his 2300 sq ft house most of the winter in NY state with their built in pizza oven and a greenhouse. Can be done
    Last edited: Nov 8, 2013
  18. DevilsBrew

    DevilsBrew Minister of Fire

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    Passive design is great. I have no problem with it and want to use it in a future home BUT...go through a real winter and then print the story. Live in an area that rarely has clear skies all year long. Solar power is useless here.
  19. DevilsBrew

    DevilsBrew Minister of Fire

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    Buffalo, Cleveland, Erie, Pittsburgh, and Rochester are not part of NE.
  20. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    He said "the" NE. Meaning the North East. Not New England.
  21. begreen

    begreen Mooderator Staff Member

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    I have lived in NY and WA and CT. Without a doubt the northeast gets a lot more sunshine in the winter. NY sun.JPG WA sun.JPG
  22. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    Ain't it the truth. Took a Cessna up from Bellingham Airport one day and wandered up to Vancouver and back. On top there was nothing but solid clouds as far as the eye could see. Had to go down on the deck to see any sights.
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  23. woodgeek

    woodgeek Minister of Fire

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    Of course, I think the claim is that the passive haus can be heated with a 'hair dryer' or 1.5 kW or 5000 BTU/h without any passive solar input. So y'all are arguing about sun for no obvious reason. Its just square footage and R-value, etc and they can def get the heat demand that low even when its cold outside. The bigger point is that the min cost of ownership is usually a cheaper, less well insulated structure that can be heated by two hair dryers (actually one small 10 kBTU/h minisplit) and a smallish, grid-tied PV array to run it.
    Last edited: Nov 8, 2013
    Floydian likes this.
  24. Seasoned Oak

    Seasoned Oak Minister of Fire

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    No threat of ventilation starvation in my house. The humidity goes as low as 25% in winter.
  25. Frozen Canuck

    Frozen Canuck Minister of Fire

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    Ummm...yes we refer to that in the biz as over ventilation. A bad thing.

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