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How to build a cheap Passive House

How to save energy through both societal and individual actions.

Re: How to build a cheap Passive House

Unread postby Zarquon » Wed 01 Feb 2017, 18:33:08

A free blower door test is nice. Can you get two - one before your next renovation project, and one after? Probably not...

They let this physicist play a while with a blower door:
http://physics.ucsd.edu/do-the-math/201 ... his-joint/
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Re: How to build a cheap Passive House

Unread postby KaiserJeep » Wed 01 Feb 2017, 22:17:37

baha wrote:Brrrr...sounds too cold to me.

Another reason to oversize the PV is to have more power on a cloudy day. On those days when you can't even tell where the sun is, a modern 7 kw system will still make about 1 kw. Enough to keep the frig, freezer, and internet running.


frankthetank is speaking of SW Wisconsin, which is well inland and Zone 4 on the map I showed you earlier, so he is discussing a climate that is 10 degrees colder than I would be on the shore of the lake.

baha, one reason I am considering BOTH Solar PV AND the wind turbine, is that the breezes are fairly constant in the beach areas of the lake, and frequently blow all night long, when PV output is zero, and electricity consumption very low. This may allow me to begin the morning routine including the 10 degree space heating thermostat bump-up and induction cooking of the breakfast meal, with full or nearly full batteries.

If you have an all-electric Passive House, the obvious primary HVAC system is a heat pump. In heating zone 7 I would agree that inexpensive air-to-air heat pumps are the way to go, and one should use the smaller sized units in individual zones, perhaps even zoning each room separately. In Wisconsin, the way to go is one largish variable speed central compressor unit, and individual evaporator units in each room/zone. The ground source heat pump is the selection here, even though it has a larger installation charge as one must either drill and grout a couple of geothermal wells or excavate and bury coils of plastic plumbing over a wider area. The geothermal system is not a DIY project, but the small air-to-air heat pumps could be, if one used pre-charged components and pre-charged plumbing lines.

Whether building a new Passive House or retrofitting an existing one to reduce energy consumption, educate yourself first. Even if you don't DIY anything, you need to be a knowledgeable consumer. In this topic as with most things, planning is everything.
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Re: How to build a cheap Passive House

Unread postby frankthetank » Thu 02 Feb 2017, 13:57:50

The 8 day cloudy stretch had little to no wind here (constant fog/stratus/drizzle). I live in a river valley so our winds are always much less (although in the spring that works to our advantage with warmer temps).

Today its in the teens, windy but the sun is shining bright. So today would be an excellent solar/wind day. My furnace has hardly run with the early Feb Sun warming the house very nicely.
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Re: How to build a cheap Passive House

Unread postby Tanada » Fri 22 Dec 2017, 11:48:37

frankthetank wrote:The 8 day cloudy stretch had little to no wind here (constant fog/stratus/drizzle). I live in a river valley so our winds are always much less (although in the spring that works to our advantage with warmer temps).

Today its in the teens, windy but the sun is shining bright. So today would be an excellent solar/wind day. My furnace has hardly run with the early Feb Sun warming the house very nicely.


How did your house weather the hot summer temperatures/ Were you able to stay more passive or did the A/C-fans have to run hard in the peak cooling months?

My home is in a fairly breezy spot at the corner of my community so we are the wind break for the neighbors instead of the other way around. This means significant losses to outside air even in the best of circumstances because the 1970's era construction does not have thick walls with heavy insulation, just 2x4 studs with 3" fiberglass and whatever insulation they put under the vinyl siding when they installed it. The attic fan for spring/fall cooling ensures we will never have a 'tight' building envelope but I am certain thicker walls and insulation would have made a huge difference. Unfortunately that kind of a retrofit is more cost than it is worth, better to tear down a house and just build an efficient one than to take on a project like that.
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Re: How to build a cheap Passive House

Unread postby GHung » Fri 22 Dec 2017, 12:40:38

Tanada wrote:
frankthetank wrote:The 8 day cloudy stretch had little to no wind here (constant fog/stratus/drizzle). I live in a river valley so our winds are always much less (although in the spring that works to our advantage with warmer temps).

Today its in the teens, windy but the sun is shining bright. So today would be an excellent solar/wind day. My furnace has hardly run with the early Feb Sun warming the house very nicely.


How did your house weather the hot summer temperatures/ Were you able to stay more passive or did the A/C-fans have to run hard in the peak cooling months?

My home is in a fairly breezy spot at the corner of my community so we are the wind break for the neighbors instead of the other way around. This means significant losses to outside air even in the best of circumstances because the 1970's era construction does not have thick walls with heavy insulation, just 2x4 studs with 3" fiberglass and whatever insulation they put under the vinyl siding when they installed it. The attic fan for spring/fall cooling ensures we will never have a 'tight' building envelope but I am certain thicker walls and insulation would have made a huge difference. Unfortunately that kind of a retrofit is more cost than it is worth, better to tear down a house and just build an efficient one than to take on a project like that.


It goes to how many obsolete structures we have from an energy standpoint. When we had a remodeling business, I sometimes pointed out the long-term costs people faced when refurbishing old structures. Many had a "This Old House" mentality, and wanted the charm of living in, and recycling, old structures, but didn't want to pay the costs of doing it right.

We found that foaming the walls and adding vapor barriers in the attic, along with a lot of blown-in attic insulation, was the most cost effective solution. Still, a lot of work and costs there. And adding air conditioning to an old leaky structure can be a horrible mistake, especially in humid environments. Condensation in the walls can destroy those buildings in a few years.

As for attic fans, etc,, wonderful things excepting the security issues a lot of people fear from leaving windows open. I grew up in the South with attic fans; cool the house at night so it stays cooler during the day. Times were different then, and crime wasn't such an issue. And we've always had dogs keeping watch.

Our house was over-built to modern standards in terms of insulation and sealed walls/ceilings, but was largely designed to be open to the outside, allowing prevailing winds to waft through in the summer. Over-hanging eaves allow plenty of winter sun in for passive heating (more effective than I ever dreamed or calculated), and provide shade in the summer, eliminating radiant solar heating in summer months, for the most part. All windows are opened in the spring and stay open until fall, especially the high windows in the open living area that allow hot air out. An older picture from the south here:

Image

Prevailing winds come in from the NW (left) and cool the whole house in summer. We grow seasonal vines to shade the west side in the evening. The master suite has a small AC unit for any nights that get sweltering, but doesn't get used a lot. The entire north side of the house is earth-bermed.

Of course, not too many people have six years to build their own house, or are in a situation to design a house like this, but I see most homes that are built more for aesthetics than function. If more homes were properly designed to be site-specific, and form followed function, they would be cheaper to live in and would require far less energy. A home like this also requires occupants to be involved in managing things and a willingness to adapt to seasonal changes; open and close windows and thermal curtains as conditions warrant, etc.

Easier to tell Alexa to turn up/down the thermostat, eh?

I've designed a few houses based on the concepts I used, mostly smaller homes, and hope to build one for my daughter in a year or two. We have a perfect south-facing site about 1000 feet from our current home. We may even build the smaller home for us and give this house to daughter and her kids. The prime directive is that all structures on the property be off-grid, passive/active solar, and no loans associated.
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Re: How to build a cheap Passive House

Unread postby Tanada » Sat 23 Dec 2017, 08:32:20

baha wrote:Tanada - Adding insulation to walls is a pain but it can be done cheap.


CHEAP???

Inigo Montoya wrote:You keep using that word. I do not think it means what you think it means.
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Re: How to build a cheap Passive House

Unread postby KaiserJeep » Sat 23 Dec 2017, 13:33:11

Cheap is of course a relative term. I believe what baha means is if you are paying for conventional construction, either a new structure or a remodel, adding another R10 of insulation under the drywall is cheap, only the material cost, because anybody who can hammer a nail or use a screw gun can do this. Then the drywall and finish carpentry expenses are (basicly if not exactly) the same as without the foam.

But you are correct as well, in general construction is not cheap.

My problem with what he is doing is entirely different, because I do not live in the relatively mild climate of the Carolinas. If I were to add 2" of interior foam to a house in either Wisconsin or Nantucket, the structure would rot. In a cold climate, there is a temperature gradient between the inside heated moist spaces and the outside cold dry spaces. Moisture transpires through the walls and if that temperature called the "dew point" were to occur in the fiberglass/wood conventional wall, moisture would soak the insulation, and the structure could form mildew or even dry rot. The form of add-on insulation he describes may work perfectly well in the South, but in colder climates, it is better to strip off the exterior cladding and add the foam to the existing sheathing. Then an additional layer of sheathing is used, along with a a rain barrier then a moisture-removing mesh that allows air to circulate under the siding to dry both transpired moisture and any rain leaks (perhaps from hurricane winds). In this type of construction, the dew point temperature is reached in the foam, where liquid water cannot exist. The water weeps out at the bottom of the siding as would any wind-driven rain.

If these topics interest you, allow me to reccomend: http://www.greenbuildingadvisor.com/
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Re: How to build a cheap Passive House

Unread postby GHung » Sat 23 Dec 2017, 15:46:03

baha wrote:Ghung - I wish you hadn't posted that pic...My wife saw it and said we are moving to the mountains :) Nice place! I always wanted a house built into the side of a south facing mountain, but women have this thing about windows :)


Women are right. Windows are wonderful and bring in plenty of light and fresh air. My solution to having almost half the exterior walls below grade was to put utility spaces, closets/storage and bathrooms towards the back of the house. Living spaces are on the window (south and west) side of the house. This also meets code because living spaces have to have more than one means of egress in case of fire (doors and windows). Inspectors don't care if bathrooms have windows as long as they have vent fans.

Utility rooms on the back (below-grade) side don't need to be heated/cooled either. Ours stay cool and comfy year 'round with no heating or cooling, and our root cellar is great for food storage; currently about 50 degrees. Thing is, our house actually cost less per square foot than many conventional homes around here. No windows or exterior siding to install or maintain on that side of the house. We just sprayed that green foam goo on the exterior of those concrete walls, added a lot of drainage, and backfilled. That waterproofing goo is guaranteed for 50 years but will likely last forever underground. The guy had a little pile of over-spray at one corner and I couldn't pull it apart after it cured. We've had no problem with condensation or mold in those spaces even though we live in a humid environment and don't run AC or dehumidifiers; something I had worried about.
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Re: How to build a cheap Passive House

Unread postby GHung » Sat 23 Dec 2017, 15:59:37

KJ said; .... the structure would rot. In a cold climate, there is a temperature gradient between the inside heated moist spaces and the outside cold dry spaces. Moisture transpires through the walls and if that temperature called the "dew point" were to occur in the fiberglass/wood conventional wall, moisture would soak the insulation, and the structure could form mildew or even dry rot...."


Even here in the South, my brother and I made a lot of money repairing damage as you describe. Humidity, AC in the summer and cold in winter (yes, it gets cold here) moves the dewpoint into not-sealed walls. People insist it's a leak somewhere, and don't want to hear that the entire envelope of their house was improperly constructed. Codes and inspectors now require well-sealed vapor barriers inside and out, as all air-conditioned structure should have. House wrap like Tyvek acts like Gortex and lets the wall breath a little without letting moisture in, but I've seem some house built that way get wall mold, especially around windows and doors. Tyvek will actually allow some water vapor to pass into the wall. Not good if that's where the dewpoint is.

Older houses generally didn't have these problems because they were so leaky, and didn't have AC in the humid summers.
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Re: How to build a cheap Passive House

Unread postby GHung » Sat 23 Dec 2017, 16:35:56

pstarr wrote:Ghung, you have accomplished a great deal. And should be proud. :) 8) It is an example that is sorely ignored in modern suburbia. They build only for garage and street access, instead of toward the sun. Cheaper to run utilities a few feet less then appropriate. Makes me so mad :-x


Thanks, P, though I admit there was a lot of luck involved. Also, there were times in my life when I struggled to pay for basic things like utilities. I spent a lot of time studying how I could build a forever home that largely heated, cooled, lighted, and powered itself. I stuck to some basics and just did it. Didn't take many vacations though. Jeez, it occurs to me the last time I flew was 22 years ago today.

Some folks aren't homebodies and I understand that, but, having seen enough of the world, I was lucky enough to find a place I belong, so I just dug in. It also probably gives the family a sense of stability; the "family home place", now with it's third generation living here since my daughter settled back here. I have to admit that the area is probably a little 'small-town' for her giant personality, but we keep her grounded for the most part. She's very "peak everything" aware, so struggles a bit. If she didn't have kids here in a great school (and an ex-husband, shared custody, all that), she would likely be in Alaska or Singapore, or somewhere else, but knows she can always come home, as do all the kids. They may have to live in an old camper for a while.... 8O
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Re: How to build a cheap Passive House

Unread postby KaiserJeep » Fri 29 Dec 2017, 15:35:12

baha wrote:And Yes, it will cause condensation on the windows, sometimes ice. You have to wipe them down in the morning and let them dry in the Sun. Moisture is something I still need to deal with...


Drying condensation sounds like a good thing. In Virginia my second house had aluminum triple track windows, no thermal breaks, and we sometimes had 1/2" frost layer on the frames in Winter, a maintenance headache I addressed each Spring.

Note GHung's post above about repairing houses without vapor barriers. The moisture you should be concerned with is that which you cannot see, concealed in your walls. I can't be specific, because I don't know about the existing vapor barriers or the vapor permeability of the foam you clad the interior with. You should read the website I linked to and then assess any required changes, vapor seals, vents, etc to keep your home structure and wall cavity insulation dry.

Best of luck. I have a similar desire to improve insulation on the Nantucket property, but today's labor costs are so high there, that I cannot make a mistake. I'm still learning by research.
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Re: How to build a cheap Passive House

Unread postby KaiserJeep » Mon 01 Jan 2018, 15:09:26

The idea with a vapor barrier is to put it in place under the outer wallboard. That's the implication of "barrier", you want to prevent vapor infiltration into the walls. When 2x6 exterior wall construction with 50% more insulation first became common a few decades back, taped plastic film was used over fiberglas batts. Every time the vapor barrier was pierced by new wall receptacle retrofits or even thoughtless picture hanging, water saturated insulation in the area would result. So they developed Kraft paper fiberglas batting, vapor permeable to allow the wall cavities to slowly breathe and dry out.

The exterior barrier is a rain barrier that prevents liquid water penetration but allows vapor to exfiltrate and drain away as liquid water, without saturating insulation or wooden framing. So the rain barrier is also vapor permeable, a barrier to liquid water only. In older houses where insulation is blown into empty wall cavities, the wooden sheathing is drilled into and plastic vents are installed in each wall cavity, one vent per each two feet of vertical stud height in each wall cavity. Then a rain barrier and ventilation mesh is used, and then siding which allows vapor to permeate while stopping rain.

You can't afford to get this wrong, you need to be informed about proper construction practices. You cannot simply add insulation where you want and how you want. Retrofitting smaller windows is another problem - it breaks the vapor barrier and the rain barrier both, and creates rot in each such window frame. Many houses were destroyed by window replacements before we understood that in the long run, you either need to order custom windows that exactly fit existing rough openings, or you need to peel back both the exterior and interior wall coverings, and re-frame the opening with a proper flashing system including a rubber membrane and the right caulk in the right places, and using vapor proof closed cell spray foam to fill voids on the inside. It has turned out that wood-eating insects are really fond of most open cell aerosol foams, especially damp ones.

Do the research first, then the construction. It's your house, man - don't destroy it with ill-concieved remodeling. I made my own mistakes before I learned, my first home was a Victorian with plaster walls, aluminum storm windows over 100-year-old wooden double-hung windows, a rubble stone foundation, no wall insulation, aluminum siding over rotting wood covered with lead paint. After about two decades of watching "This Old House", I understood all my mistakes.
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