# Passive houses, you can heat them with a hair dryer



## begreen (Nov 8, 2013)

http://www.seattlepi.com/realestate/article/Seattle-gains-super-efficient-Passive-Houses-4684859.php
http://kuow.org/post/house-you-could-heat-hair-dryer
http://www.passivehouse.us/passiveHouse/PHIUSHome.html


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## Frozen Canuck (Nov 8, 2013)

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.


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## peakbagger (Nov 8, 2013)

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.


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## stoveguy2esw (Nov 8, 2013)

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


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## Jags (Nov 8, 2013)

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.


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## Seasoned Oak (Nov 8, 2013)

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.


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## peakbagger (Nov 8, 2013)

_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.


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## Jags (Nov 8, 2013)

peakbagger said:


> Highly unlikely, optimal house design...


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.


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## begreen (Nov 8, 2013)

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.


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## woodgeek (Nov 8, 2013)

stoveguy2esw said:


> 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



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).


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## DickRussell (Nov 8, 2013)

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.


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## woodgeek (Nov 8, 2013)

peakbagger said:


> 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.



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


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## DevilsBrew (Nov 8, 2013)

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.


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## begreen (Nov 8, 2013)

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.


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## Frozen Canuck (Nov 8, 2013)

DevilsBrew said:


> 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.



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.


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## DevilsBrew (Nov 8, 2013)

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.


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## begreen (Nov 8, 2013)

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


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## DevilsBrew (Nov 8, 2013)

Frozen Canuck said:


> 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.


 
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.


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## DevilsBrew (Nov 8, 2013)

begreen said:


> Look at Dec and Jan averages and I think you will find the NE ahead for sunshine.


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


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## BrotherBart (Nov 8, 2013)

DevilsBrew said:


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



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


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## begreen (Nov 8, 2013)

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


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## BrotherBart (Nov 8, 2013)

begreen said:


> Look at Dec and Jan averages and I think you will find the NE ahead for sunshine.



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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## woodgeek (Nov 8, 2013)

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.


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## Seasoned Oak (Nov 8, 2013)

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


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## Frozen Canuck (Nov 8, 2013)

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


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## jebatty (Nov 9, 2013)

peakbagger, I too accept the concept of the passive haus and at the same time realize that most of the media-hyped passive haus' are high end, out of financial reach of most people. But we all know it is not hard or particularly expensive to build a highly energy efficient home, even if it cannot be heated by a hair dryer. Besides, one passive haus in one location is not the same as a passive haus' in another location: local climate is important. 

The extra cost to build not being worth the cost, though, is not an easy conclusion. What we have now for homes, and have had in the lifetimes of most of us, is the benefit of "cheap" energy which allows us to waste energy rather than conserve it; plus, we have advances in technology that allow in new construction approaching and and even achieving the passive haus. "Cheap" energy though has a very large cost in today's world which we are not paying; instead we are taking out a loan from nature that we will not be able to pay back. If we paid the true and real cost of energy, all of us would do much, much more to conserve energy, and then the passive haus would be within reach.

I also think we have got to let go of the concept of payback. It is artificial and meaningless in the natural world. It's only meaning is in the superstructure that humans have built on the natural world foundation of balance and sustainability to advance the human concept of profit and wealth. That foundation cannot support anything for long that does not take great care to maintain the balance and sustainability of its foundation. The facts now clearly show that the balance and sustainability of the natural world that has been around for a very, very long time is in major jeopardy.


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## woodgeek (Nov 9, 2013)

I totally agree Jim. Some would point out however that the cost of energy required to make passiv haus worthwhile is significantly more than the current price of grid-tie solar w/o rebates (at least with most US lower 48 climates and solar resources).  So it is always cheaper (and uses less construction materials) to just build a lossier house with a bigger PV array.

I guess, as someone who was a kid in the 70s energy crisis who gave it a lot of thought back then, I am excited that we can now build 'net zero' houses for not much more than regular code houses.  And unlike the experimental houses of the 70s and 80s, they just work and are comfortable. And once a house is net zero, who cares if it meets passiv haus specs or not.  IMO, the whole idea of passiv haus is becoming outdated itself, in favor of building the cheapest possible net-zero house that is both durable and uses a minimum of embodied energy.


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## woodgeek (Nov 9, 2013)

Just to put in some numbers....my 2300 sq ft 1960 split level house is now patched up to the point of needing about 7500-8000 kWh of electricity for winter heat. It is coming in at around 5 BTU/sqft.hdd, which is about the level expected for current best building codes in the US. 

Passive house is basically 1 BTU/sqft.hdd, about 5x better than my old house or a new code house.  So, a 2300 sq ft passive house in my climate would only need 1600 kWh with a crappy ASHP; with a nice minisplit, that would only be maybe 1400 kWh for a season's heat.  As you know, I could make that much solar juice with a 1 kW PV array here in PA, at a incremental cost of something like $4k.  IF a structure that used twice as much as a passive haus, 2 BTU/sqft.hdd, cost $10-20k less to build (mostly by saving money on the windows), why wouldn't I go for that and just spend another $4k on the PV array?


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## jebatty (Nov 10, 2013)

I think I have resolved in my head that it is a wise use of cheap energy if it is used to achieve long term, substantial conservation of future energy use, particularly if the use eliminates or greatly reduces the need for future consumption of fossil fuels. I think solar electric, made from cheap energy, fits that criteria, as well as many other energy-saving construction techniques, e.g., passive haus type construction. 

Some numbers for my house. 1500 sq ft main level with full basement walkout, mostly finished into living space, 3000 sq ft total. Energy usage 2012-13: 4 cords of aspen for wood stove (primary space heating, electric backup); 6450 kwh for general service electric; 4300 kwh for electric heat to keep the walkout level livable during the winter and backup electric heat; and 1500 kwh for dhw; total 12,250 kwh. We have no air conditioning.

Converting 4 cords of aspen to btu = 2300 lbs/cord x 4 x 6050 btu/lb usable = 55,660,000. Converting kwh to btu = 12,250 x 3400 = 41,650,000. Total btu energy = 97,300,000. Hdd = 9500 (base 65). Btu/sq ft/hdd = 3.41 total energy usage.

Energy usage just for heat = 4300 x 3400 = 14,620,000 btu + 55,660,000 = 70,280,000 btu, which is 2.47 btu/sq ft/hdd.

Our house was built in 1956, we have replaced all windows and added considerable insulation. We are substantially better than the 5 btu/sq ft/hdd best building code standard. Our new 6.5 kw solar system is estimated to provide 8,580 kwh/year = 29,172,000 btu equivalent. Adjusted t*otal energy usage* as reduced by 0 carbon solar = 97,300,000 - 29,172,000 = 68,128,000 btu, which is 2.39 btu/sq ft/hdd.

I regard wood heat as 0 net carbon as well, so our estimated net carbon footprint is 68,128,000 - 55,660,000 = 12,468,000 btu = 0.44 btu/sq ft/hdd.


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## woodgeek (Nov 10, 2013)

Cool.  At a home heating index (HHI) of 2.47 BTU/sqft.hdd you would be closing in on net zero in a milder climate like mine (which I claimed above was doable at HHI=2).

Of course, you appear to have sized your new array to cover your plug loads and dhw.  Since the electric heating load could be offset by distributing some heat from the boiler (future plan?) with another cord of wood (to ~5 total), such a route would get you to a net-zero electricity and zero-fossil carbon point.  Nice.

A purely hypothetical wood free alternative based on minisplits at COP=3 (likely too optimistic in your climate) would be 70 MM BTU (heat) / 3414 (BTU/kWh) /3 = 7000 kWh (elec), which could be met easily by a 6 kW twin of your new PV array.  If you didn't already have the sunk cost of the boiler and storage, it would be interesting to compare the cost of an additional array + minis, (prob with a stand alone stove to help during Alberta clippers) to a wood boiler approach.

So a hypothetical net-zeroing exercise with your nicely retrofit 1950s house using just PV is a bit of a stretch, but not totally crazy.  IMO, the key enabling tech is the combination of the minisplit and grid tie PV.  With a COP=3, a given collector area of solar array can deliver 15%*3 = 45% of its incident energy as space heat BTUs, which sounds lousy until you realize that you can bank summer energy in the grid for use in the winter, not possible with solar thermal.


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## Seasoned Oak (Nov 10, 2013)

Well insulated home get heat from the residents as well. I know when we have a small gathering here the room temps keep going up even in winter. I purposely  cool down the house a day or 2 before. And this house is POORLY insulated.


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## jebatty (Nov 10, 2013)

An added plus for our house is that it faces SW, looks out over a lake, and the SW wall is mostly windows (R-8 center of glass). We get lots of passive solar heat gain in the winter with both direct sun and reflected sun off the snow cover on the lake. With 4' eaves the window are well shaded from summer sun. On sunny winter days we have little need for additional heat from the wood stove.

And you're right. Another cord of aspen would off-set our remaining carbon footprint. Ahh, the need for a simple and small wood to electric system.


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## peakbagger (Nov 10, 2013)

A  few comment on various posts

HVAC folks usually figure a person is roughly a 100 watt light bulb equivalent heat. Generally with gatherings, there is increased cooking and possibly refrigerator loads so there are some indirect sources.

I am not sure for humans but a piece of trivia is that a dairy cow puts out enough manure each day to generate 100 watts of power, A pig is 20 to 40 watts and a chicken is about 5.

In my opinion a major benefit to any house not just a passive house is independent inspection to make sure that the design is implemented in the field. Blower door tests are a good tool for infiltration but they do not do anything for poor or missing insulation unless foam is sprayed in which by default has better sealing. My modular house was built by a high end firm with a good reputation 20 years ago. When I opened up a wall for a retrofit I found the same quality issues as I see with standard construction, many small gaps not filled and insulation cut short and poor treatment of exterior wall outlets. If I was  stick built I would guarantee before a wall was sheetrocked that gaps were filled with spray foam and insulation was done right and I don't see that happening with conventional contractors. I may not get to passive haus but I expect I would substantially improve infiltration and convective loss.

NH has a model energy code that is fairly tight that is required of all new construction unfortunately, the enforcement is left up to local building inspectors and few actually check for compliance. Rather than building one of two passive houses to inspire the locality, I would rather see the overall build quality improved.

I have a lot of passive heating aspects in my house and on a sunny day they make a difference if I am home to open and close the blinds. Unfortunately the $500 plus per window cost for automated blinds isn't a good payback. I use them when I can but I expect most of those features assume a stay at home person and few households have the luxury these days.


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## Seasoned Oak (Nov 10, 2013)

peakbagger said:


> A  few comment on various posts
> HVAC folks usually figure a person is roughly a 100 watt light bulb equivalent heat. Generally with gatherings, there is increased cooking and possibly refrigerator loads so there are some indirect sources.


 I had about 8 people in my finished bsmt.(24x24) last week. Temp was going up about 1 Deg an hour. NO cooking just drinking. No other heat source. Bsmt has ZERO insulation.


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## pdf27 (Nov 10, 2013)

It should be remembered that 1 kWh of electricity in midsummer at midday isn't of the same value as 1 kWh of electricity at 6 pm in December - different generating plant will be used to make it, with associated different emissions. If your main local load is air conditioning, then going the Pretty Good House/large net zero PV array is optimal. If the main local electrical load is heating, you're going to need to have a much larger PV array to offset your emissions, at which point a Passivhaus approach is more suitable.


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## woodgeek (Nov 10, 2013)

so you don't believe PV on a grid battery is zero emissions?  Depending on the seasonal mix, couldn't it be negative carbon?  Around here the nuclear fraction is higher in the winter, and lower in the summer, so summer carbon intensity is higher for conventional power.


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## wazzu (Nov 10, 2013)

So just how much does one of these passive houses cost? I am guessing that for most of America it is way out of reach. Unless you can build these houses for a maximum of 200-250K it just won't work out for regular folks. The other thing is finding someone who actually knows how to build one where you live. It sure does cost a lot of money to be "green" or "sustainable".


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## woodgeek (Nov 10, 2013)

There are a lot of estimates out there from $10-100/sq ft extra cost of construction.  The following blog suggests that the cost of ownership is lower than a code house:

http://www.greenbuildingadvisor.com...n-misconceptions-about-passive-house-standard

IOW, if the extra cost is rolled into a mortgage, the additional mortgage payment is less than the energy savings per year.

Personally, I am skeptical of that.  If a current 2500 sq ft code house (properly constructed) has a winter heating bill of $1000 on a heat pump or nat gas, than the additional cost of the passive house would need to be <$20k and the final heating bill $0 for the 'additional mortgage costs less than energy savings'.

My WAG would be a cost conscious builder of a passive house would run at least $20-30 sq ft extra, maybe an extra $40-60k on a 3 bedroom house.  I think a PGH would be a significantly lower upcharge.....that is the point of the 'pretty good house' concept, minimum cost of ownership.

Of course, in a lot of the country houses are selling for north of $150/sq ft, even my estimate would only be a 15-20% upcharge.


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## Pettrix (Nov 10, 2013)

There is a lot of misconceptions about Passive House designs and costs. Let me start by saying that there are one story homes that use passive solar to heat them and there are homes that are one story which are also passive house certified. Two story homes are more common because lot sizes are small in most areas and building up is feasible, while building wide is not possible.

The older designed 1970's+ era passive solar homes could "overheat" but technology and science has come a long way since the 1970's. Today, the passive house design is done using mathematical calculations, physics, algorithms, and a fairly complex equation that in the end will design a home to be very comfortable in the summer and provide passive solar heating in the winter. All without the overheating problems of the 1970's era passive solar homes. 

Another misunderstanding about PH (passive house) is that they don't have proper ventilation and create a haven for germs and moisture. Nothing can be further from the truth. PH use the best air ventilation systems out there. A properly vented home is key to a PH design. The homes are built air tight and tested to achieve less than 0.60 ACH. The HRV/ERV mechanical ventilation systems are used to bring in fresh and filtered air into the home while removing stale air from the home. This creates a very healthy environment for the homes occupants and creates a very energy efficient home. More design information can be found here: http://intuswindows.com/passive-house/

We are fortunate in the USA (for now) that our utility costs are lower than other parts of the world. This will not last. As with anything, the costs of utilities continues to rise and why build an inefficient home that will remain standing for 50-100 years and be an energy hog? That's 100 years of high utility bills and wasted resources. PH is a scientific calculation and design that when utilized can create a home that is highly energy efficient, very comfortable, and has low heating bills during winter. All while utilizing the "free" heat of the winter sun.


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## rowerwet (Nov 10, 2013)

my parents ranch has large glass windows facing south, on sunny days the house gets enough heat from the sun to keep the house warm. Since it was built to weather "the coming ice age" (early 80's) they have saved a ton on oil. they still switched to pellets for heat in 2009. 
two story houses have the big advantage of "reusing" the heat generated during the day, as the upstairs bedrooms will be warm long after the sun has set. you don't get that with a ranch.


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## Pettrix (Nov 10, 2013)

rowerwet said:


> my parents ranch has large glass windows facing south, on sunny days the house gets enough heat from the sun to keep the house warm. Since it was built to weather "the coming ice age" (early 80's) they have saved a ton on oil. they still switched to pellets for heat in 2009.
> two story houses have the big advantage of "reusing" the heat generated during the day, as the upstairs bedrooms will be warm long after the sun has set. you don't get that with a ranch.



The above "issue" is addressed in a Passive House by utilizing *thermal mass* within the home. The thermal mass will moderate the homes temperature fluctuations and it will radiate heat during the off peak hours when the sun is set. So a ranch can have the same benefits as a two-story if the ranch utilizes thermal mass within the home. Thermal mass would be an exposed concrete floor or wall. Ceramic tiles will also work but exposed concrete works best. Having the southern sun hit the exposed thermal mass works best. It will put off "free heat" at night when the sun is gone.


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## woodgeek (Nov 10, 2013)

Pettrix, you seem to be conflating Passive Houses, defined as houses with heat losses and air leakage below certain thresholds (and nice HRV ventilation), with passive solar houses.   Passive Houses can utilize small amounts of passive solar gain, but do not need to.


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## byQ (Nov 10, 2013)

Pettrix said:


> The above "issue" is addressed in a Passive House by utilizing *thermal mass* within the home. The thermal mass will moderate the homes temperature fluctuations and it will radiate heat during the off peak hours when the sun is set. So a ranch can have the same benefits as a two-story if the ranch utilizes thermal mass within the home. Thermal mass would be an exposed concrete floor or wall. Ceramic tiles will also work but exposed concrete works best. Having the southern sun hit the exposed thermal mass works best. It will put off "free heat" at night when the sun is gone.



I'm building a small house and I'm following this concept. It costs no more to build a house facing south than in any other direction (unless obstacles are present like trees or street orientation) so every house built should do this - for free energy at minimal cost. And radiant heat is the best kind of heat.


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## jebatty (Nov 11, 2013)

> It costs no more to build a house facing south than in any other direction (unless obstacles are present like trees) so every house built should do this - for free energy at minimal cost.


Could not agree more. When we bought our house in 1990 we were not aware of the passive solar potential. It took some modifications, new windows, etc. to realize the potential, and it is fabulous. Plus we have a very bright house due to natural light, also reduced need for electric lighting, and the bright winter days help to compensate for the long, dark winter evenings and nights.


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## pdf27 (Nov 12, 2013)

woodgeek said:


> so you don't believe PV on a grid battery is zero emissions?  Depending on the seasonal mix, couldn't it be negative carbon?  Around here the nuclear fraction is higher in the winter, and lower in the summer, so summer carbon intensity is higher for conventional power.


I don't believe net-zero electricity consumption necessarily equates to net zero emissions - it's all going to depend on what the mix is when you're generating and when you're consuming. Where I am the winter consumption peak is much higher than the summer peak, and I'm far enough north that the PV contribution is close to zero in winter. You'd need to generate getting on for twice your consumption to break even, depending on exactly what time of day you use the power at.

http://www.gridwatch.templar.co.uk/ has got the whole UK data in 5 minute increments if you're interested...


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## woodgeek (Nov 12, 2013)

we agree.  I will have to look up the seasonal carbon intensity in the US, region by region, but I know the peak demand in all the US interconnects are in the summer, and they often discount power in the winter (to keep the nukes from throttling back).

My own usage follows a strong winter peak pattern (about 60% of total use Dec-Jan-Feb).  I used to buy that discounted (mostly) nuke power (for $0.075/kWh) for my winter heat.  When that deal went away, I switched to 100% local wind (at $0.135/kWh, currently).  Of course, your comment applies just as well in principle to my case if all the wind blew in the summer, and I 'bought' my wind power in the winter.

So I looked it up: http://en.wikipedia.org/wiki/Wind_power_in_Pennsylvania  Looks like a relatively constant resource, with a lull in the summer (when I use little power).

So, I don't fool myself that I am carbon neutral, but I am probably a lot lower carbon intensity than other options I have access to.


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## Floydian (Nov 13, 2013)

The Passivhaus vs Pretty Good House vs Code House+Net Zero discussion is an interesting one.

Here is my take...

Passivhaus-Likely beyond a reasonable ROI for most folks but as close as one can get to a guarantee of low energy usage and  the highest level of comfort. The PHPP software is probably the most advanced energy modeling tool available and if money is not an issue then going PH is great. If someone can afford this than achieving NZ would be a small additional cost.
Here is a PH that could certainly be heated by a hair dryer  http://www.greenbuildingadvisor.com/blogs/dept/green-building-news/striving-passivhaus-affordability . This house comes in at 3.1kbtu/ft sq/ yr beating the PH standard of 4.75k btu/ft sq/yr by over 30%. Yet to be determined if the 1.4 KW PV system can bring the house to NZ.
Another PH with affordability in mind http://www.greenbuildingadvisor.com/homes/passivhaus-budget . This in a not so demanding climate. Probably "only" a PGH in the northeast.

Pretty Good House-IMO this is the winner. High attention to air tightness with HRV/ERV, minimal thermal bridging with high R values, triple pane windows with orientation specific glazing(high solar heat gain on south windows)+proper overhangs for summer shading and a ventilated rainscreen. Basically everything that you get with PH just dialed down a few notches on performance and cost.
The important thing for me is that a PGH should be able to achieve a high degree of comfort with simple point source heating-a mini split or two with a small wood stove. Increased durability should also be part of the PGH vs the Code House.

Code House+NZ-My biggest problem with this approach is that I feel it is skimping on the enclosure. While achieving NZ is certainly a good thing, the Code house lags behind in the comfort game, requiring more heat distribution throughout the house to achieve the same level of comfort as the PGH. IMO the additional heating system cost should go into a higher performance enclosure to take advantage of increased durability, low energy requirements for the life of the building and simple point source heating/cooling with the most efficient mini splits(+wood stove). Then add the PV to get to NZ when funds allow in the future.

Noah


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## jebatty (Nov 13, 2013)

As our *total energy usage/year* is 97,300,000 btu, which is 28,618 kwh / 3000 sq ft = 9.5 btu/sqft/year.  Just for heating (we have no a/c) is 6.9 btu/sqft/yr. Subtracting out the solar, it comes to 6.7 btu/sq/ft/yr. On a net 0 basis, if wood is subtracted out as being net 0, then our *total energy usage/year is*1.2 btu/sq/ft/yr of fossil fuel energy.

For a 1956 house, new windows and added insulation, on a total energy basis, I would think anything less than 10/btu/sqft/yr probably qualifies as a Pretty Good House.


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## Floydian (Nov 13, 2013)

jebatty said:


> As our total energy usage/year is 97,300,000 btu, which is 28,618 kwh / 3000 sq ft = 9.5 btu/sqft/year. Just for heating (we have no a/c) is 6.9 btu/sqft/yr. Subtracting out the solar, it comes to 6.7 btu/sq/ft/yr. On a net 0 basis, if wood is subtracted out as being net 0, then our total energy usage/year is1.2 btu/sq/ft/yr of fossil fuel energy.



Jim,

It looks like you divided your KW by your square footage, so that would be 9.5kw/sqft/year. 97,300,000 btus/3000 sq ft=32.4K btu/sq ft/year. Still not a bad number for an upgraded 1956 house in your HDD area.

Passivehaus standard is 4.75K btu/sq ft/year (heating only).A 3000 sq ft PH would have a annual heat load of 14.2MM btus/year.

To me a PGH would be around 10K btu/sq ft/year. About double PH standard.

Noah


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## jebatty (Nov 13, 2013)

whoops!


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## Seasoned Oak (Nov 13, 2013)

Id like a  well insulated place but i wouldnt want to go too far as i would not have any use for the 
woodstove anymore.


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## Ehouse (Nov 13, 2013)

Seasoned Oak said:


> Id like a  well insulated place but i wouldnt want to go too far as i would not have any use for the
> woodstove anymore.




Me too.  I don't want a bigger wood stove and I can't get one much smaller without going to a ship stove.  I want to live in a house, not a contraption.


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## woodgeek (Nov 13, 2013)

Ehouse said:


> Me too.  I don't want a bigger wood stove and I can't get one much smaller without going to a ship stove.  I want to live in a house, not a contraption.



Bad news, your house IS a contraption.  Its just a subtle one.


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## Ehouse (Nov 13, 2013)

woodgeek said:


> Bad news, your house IS a contraption.  Its just a subtle one.




I know Geek, and I agree with you, and I'm also fascinated with the tech advancements and innovations ongoing, but I love the unmatchable 19th century architecture and wood work of my present home.  I have a high tech house on hold that I could probably heat with a hair drier, but to finish it would bankrupt me.  

For now, the best applications for innovative (or retro) tech for me are those that allow me to continue to live in this old rambling Victorian.


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## Badfish740 (Nov 13, 2013)

I'm going the "Pretty Good House" route and seeing what happens.  We have a 1200SF (counting the finished basement) one story ranch, which we're planning on squeezing two bedrooms out of the attached garage and at the same time sealing up the envelope of the house, applying 2 or more inches of foam board to the outside walls, and blown cellulose to the attic.  The goal will be R-25/30 walls and an R-60 ceiling.  I figure we'll be able to get more out of the wood heat and just the oil heat less, which would be good enough for me considering the relatively small investment it will take.


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## Seasoned Oak (Nov 13, 2013)

Badfish740 said:


> sealing up the envelope of the house, applying 2 or more inches of foam board to the outside walls, and blown cellulose to the attic.  The goal will be R-25/30 walls and an R-60 ceiling. .


How about the Finished Bsmt foundation,any insulation there?  And the Bsmt floors?


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## Badfish740 (Nov 14, 2013)

Seasoned Oak said:


> How about the Finished Bsmt foundation,any insulation there?  And the Bsmt floors?



About 1/2 of the basement is finished and has 4-5" of fiberglass batts in the stud bays-nothing spectacular.  The other half is unfinished and is utility space (where the oil and wood furnace reside).  No insulation in the floor.  The rim joist is stuffed with fiberglass all the way around though.  I will admit to not knowing much about how this affects the overall envelope of the house in terms of insulation, but I have to believe that making the house as close to airtight as possible (it's nowhere near that right now), and insulating the aboveground walls and ceiling much better would have to make a big difference in our overall comfort and oil usage.  Right now the house is leaky as heck and has R-5 walls/R-8 ceilings.  

In terms of investment it will be low for me because I'll be doing it all myself.  Air sealing will consist of me, my dad, my FIL, and A LOT of cans of Great Stuff.  The plan after that is a good application of Tyvek, then some foam board.  I'm still debating on how much.  2" x 4' x 8' foam runs about $34 a sheet at the local Lowes.  Luckily my house is small and simple (25' x 50' rectangle-one story)-I figure about 48-50 sheets will do it.  The really ambitious project would be to apply foam horizontally, tape the seams completely, and then apply an additional layer vertically with the seams taped again, and battens applied which will help hold the foam tight to the house and provide a nailer for the Hardi-plank siding which will finish it off.  The siding will need to be done anyway because we'll be moving some windows as a result of adding two bedrooms by converting our attached garage.  It's probably a few years off at this point, but I plan on documenting every step of it here and reporting on the results.


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