new home build, Passive House questions

My wife and I are planning to build a new home next year and we have a lot of questions.

Let me outline our situations as best I can:
-We live in Manitoba Canada and plan to build just outside of Winnipeg so our winters are -35C and our summers can be +35C. Heating and cooling are the major issues I'm currently trying to work out.
-I'm working with a model right now that has 2000 square feet of living space spread out over two floors and no basement with about 800 being a separate suite that I can turn into our offices or develop as needed later (maybe a duplex)
-We're planning the basic south facing windows with thermal mass inside to collect as much winter sun as possible.

-I have no idea how to address cooling in the summer other then to introduce an air conditioner somehow into the system so any ideas on this would be greatly appreciated.
-For heating I'm thinking of using solar thermal hot water heating panels on the roof with a solar electric system to pump the water. I think we will have to use a large stratified water tank to store the heat energy and rely on a high efficiency HRV system to control heat loss with our air changes.
-The house wont be off grid but I don't want to rely on the grid for any of the climate control demands of the house.

Here is one of my key questions, I'm really liking the rocket mass heaters as a secondary heat source for the cold winter months however because its going to be a passive house how do I manage the air changes necessary to feed the mass heater with air? Can I plumb the exhaust into the HRV system so that we aren't just pulling raw cold air into the system? How would I deal with the steam and keep it from frost damning and plugging the HRV?

Should I look at another secondary heat option?

Very interesting project Sean. As Iam sure you know, building to the passive house certification level of performance will be an enormous challenge in your climate. Iam all for achieving the levels of airtightness and insulation that will be necessary but I have to question the financial feasibility of your solar thermal heated floors.

I think that if you do a good job on your passive solar design (but more importantly the air-sealing and insulation) then the solar thermal radiant floors will be a very expensive system to squeeze out more performance from the sun. As you mentioned it will be a VERY large storage tank to achieve the BTU requirements and solar thermal systems are notorious for trouble and maintenance.

Its sounds like you are familiar with Thorston Chlupps prototype house in AK and I would strongly recommend you get in touch and hire him for consultation if possible.

http://www.greenbuildingadvisor.com/blogs/dept/green-building-news/passivhaus-design-alaska-s-frigid-climate

I usually recommend avoiding combustion appliances like the plague but having a RMH, woodstove or masonry heater will probably be necessary in your climate as the backup heat source. I would suggest using Mini-split heat pumps as the primary heating system which will provide the cooling and dehumidification needs as well.

I dont think I understand your heat recovery ventilator (HRV) RMH question. Surely you dont mean exausting RMH into exahust of HRV? I would supply a makeup air duct directly to the the RMH or woodstove. I would take the money you plan on spending for the solar radiant floors and buy an extremely efficient HRV like the one made by Zhender.

Yea I was wondering about running the exhaust through an HRV... It seems like a really good way to recover as much heat as possible for the incoming air.

I guess the real thing plaguing my mind is that the RMH will require a lot of air to feed the fire, if I plumb in air direct from outside how do I make it air tight and how will -30C air effect the burn? The exhaust isn't so much a concern for me as the intake. It seems to me that the HRV would lose efficiency when a RMH is drawing more air into the house then the HRV is able to let out.

As far as the house I've nailed it down to either EPS on the exterior of advanced frame walls or possibly sip panels, there is a local manufacturer that makes an R48 sip panel that I think would be interesting for the walls and roof and then I'd just add a layer of R30 EPS to the roof system... all still theory.

Sean & Permies Cloud : have you been to> cchrc.org , C.old Climate Housing Research Center is a branch of University of Alaska, Fairbanks, you and I know Cold,
they know COLD!Both Through their site and in a good set of Videos on their channel at You-Tube (i do not usually recommend u-tube land at all, to much crap! ) they gently
educate the home owner and builders dealing with circa-cum polar climate issues Definitely worth a look, if you see something you find useful consider posting ! BIG AL !

P.S. in the wrong hands, and few heat exchanges SIPS panels have ruined thousands of buildings due to water vapor problems and mold mildew and rotting wood esp
laminated products ! A.L. Look for the term rain walls to under stand how it should be done ! al

Hello Sean,

-

I have no idea how to address cooling in the summer other then to introduce an air conditioner somehow into the system so any ideas on this would be greatly appreciated.

Proper design of fenestration to eave overhang ratio will address some, if not all of this. You can also consider a greenhouse for you solar collection that can be isolated from the main living structure.

-For heating I'm thinking of using solar thermal hot water heating panels on the roof with a solar electric system to pump the water. I think we will have to use a large stratified water tank to store the heat energy and rely on a high efficiency HRV system to control heat loss with our air changes.

I will probably will not be of much help to you as it sounds like you are going for the "technical-industrial" side of "green" architecture. Remember, the more technology you have the more you have to break down, and that is electricity dependent. Personally I would recommend some style of pièce sur pièce, Post-and-plank, timber frame, or combination there of.

http://www.lancestrale.ca/

-The house wont be off grid but I don't want to rely on the grid for any of the climate control demands of the house.

If you have the hose dependant on Technology, you have to think electricity and back up systems for it. Design without these constraints and you will not have these issues. The home should be designed to function perfectly well without tech, then what tech you use is simply a convenience, not a dependance.

Here is one of my key questions, I'm really liking the rocket mass heaters as a secondary heat source for the cold winter months however because its going to be a passive house how do I manage the air changes necessary to feed the mass heater with air?

You could bring it in from the outside directly to the fire box like on many wood stoves, though if the home is design to be draft proof, but permeable (breathable), you probably don't need to worry about it.

Should I look at another secondary heat option?

Not if you get the home design properly, though a methane or propane system for cooking would not be a bad thing.

Regards,

jay

Jay speaks of the tricky balance between technology, society and our dwellings. Stone tools and timber framing are forms of technology. I would argue that the technology of RMH is more complex than the technology of HRVs even though HRVs use electricity. HRVs are simply fans with dumb heat exchangers. They may be described as "technical industrial" but they are a much less risky technology than any combustion appliance. The desire to simplify is behind my advice to avoid solar thermal radiant floors.

HRVs work best when they have balanced airflows which can be hard enough as it is. Introducing an RMH to the equation upsets the balance and puts smoke, moisture, particulate and probably overly hot air into a technology not designed for it. Make up air supply ducts are relatively easy to make airtight.

Your concern about frigid supply air is sound. The Make up air duct could run through the mass of the cob or another path through the conditioned space which helps to heat it up. Once a fire is going, I think the CFMs are in the range of 10-60, not an extreme amount. Many people feel that the make up air should not be directly attached to the combustion appliance and be supplied in its general vacinity for fire concerns (backdrafting embers).

Al's statement about "thousands" of SIPs home failures is a gross exaggeration in my opinion. Maybe hundreds, but even that is a stretch and most of those failures are from poorly executed details like not sealing between the panels. Air leaks cause rot on SIPS AND conventional homes. SIPS homes are generally much more airtight than most construction.

Hello Brian,

For the sake of clarity, I will address each point the best I am able and leave it to the reader to make their own determinations or additional query.

I would argue that the technology of RMH is more complex than the technology of HRVs even though HRVs use electricity. HRVs are simply fans with dumb heat exchangers. They may be described as "technical industrial" but they are a much less risky technology than any combustion appliance. The desire to simplify is behind my advice to avoid solar thermal radiant floors.

I agree that a stone tool is technology but I do believe you are making an extreme in your comparisons that is a bit nonsensical, for neither a rock, timber frame, or RMH rely on much beyond the creators hands for it making, care, maintenance or refurbishing. None require the dependence of a failing grid system nor the complexities to generate electricity.

HRVs work best when they have balanced airflows which can be hard enough as it is. Introducing an RMH to the equation upsets the balance and puts smoke, moisture, particulate and probably overly hot air into a technology not designed for it. Make up air supply ducts are relatively easy to make airtight.

Of this there may be truth, but I do not recommend a HRV in general, as a home well designed need none.

Many people feel that the make up air should not be directly attached to the combustion appliance and be supplied in its general vicinity for fire concerns (backdrafting embers).

I would suggest that there are just as many that do recommend them, and many of these are fire and wood stove installers. When done correctly they have little chance of error such as backdrafting. As for my personal opinion, I have seen them work, and I have seen them not. In general, I do not see the need for them in most traditionally or naturally designed homes.

Al's statement about "thousands" of SIPs home failures is a gross exaggeration in my opinion. Maybe hundreds, but even that is a stretch and most of those failures are from poorly executed details like not sealing between the panels. Air leaks cause rot on SIPS AND conventional homes. SIPS homes are generally much more airtight than most construction.

Brian, if you have a background in general pest control, mold-fungus mitigation, or have dismantled many of these panel units after some time, then I would heed your opinion with both ears bent your way to listen closely. I do have that background, have serviced these panelling systems on numerous occasion (all installed to factor specification) and they are fraught with a myriad of challenges. They are a new technology, with a short time in actual application, and already show signs of dysfunction. I agree they are good for the manufacturing industry, great for speed and profit margins of contractors, but are difficult to service, augment, or modify. If you want to run a pipe, wire, or alter them, it is very invasive to say the least, and not easy to facilitate, which again is good for the contractor. Lastly the fact that they are "air tight" is an issue to many like myself, and I have no need for an "air tight" home only draft proof. I have, and may continue to use them in roof assemblies for certain forms of architecture, but that will be the extent of it I do believe.


Regards,

jay

Great points Jay. Didnt mean offense with the stone tool comment. I think finding the right balance of technology can be a tricky exercise when it comes to our dwellings and society in general. Its a fascinating subject with room for many viewpoints.

There are many paths to green building. I am definitely in the camp of reducing energy use of fossil fuels as much as possible. You are in the camp of natural building which aligns itself better with most of what the permies site is about. While monthly, energy use is the biggest source of most folks environmental footprints, its tough to argue against the sustainability of small, owner-built homes of natural materials. I think green building falls within this range and its a good thing to flesh out the advantages and disadvantages of both schools of thought.

The title and subject of Sean's post is passive house. Its a german born certification that focuses on energy use but many projects are achieving it through mostly natural materials. http://www.passivehouse.us/passiveHouse/PassiveHouseInfo.html

Now for the nitpick..
I dont think every home requires an HRV but I do feel every new home should be built tight enough to require mechanical ventilation. This might fall into the nitpick zone or it might be a fundamental difference between natural focused builders and more high performance "modern" builders. I think most natural builders see the benefits of mechanical ventilation and are beginning to include it.

I fail to see the difference between "airtight" and "draft proof". If a home is not getting fresh air from outside then the air inside is not as healthy as it could be. The current debate between Indoor Air Quality experts and building scientists is how much CFM of outdoor air introduction is ideal. A "draft proof" home with no mechanical ventilation has no control over the situation other than opening windows which works great sometimes but not all the times. Iam a fan of the most control possible and HRVs are a very simple technology that offer that. It could be that someday, HRVs will be considered the stone tool of healthy building (sorry couldnt resist!)

As for make up air, tight homes need it unless you want to constantly be opening windows which is a loss of control I personally would rather avoid during certain times of the year.

As for SIPS, I agree that they can cause problems. I disagree that problems you may have encountered were products and installations done appropriately. Either the manufacturer screwed up or the installer did. From my experience people have been more comfortable in their SIP homes and like them so much they insist on doing them again (even when I try to talk them out of it). I also disagree that they are good for a contractors profit margin as they are usually not. Contractors avoid them because they are different. I dont think SIPs installers or GCs specializing in them are getting rich and usually it seems they are making less because they are passionate about energy use to the point of losing money. Personally, I will probably avoid them moving forward or have the customer pay the deposit because a bankrupt company did not deliver and I lost more money than I ever made through SIPS which was not much to begin with.

Your point about accessibility is fair but I would argue that in ways this is a good thing. Look at Bensonwood's open built model for the ultimate accessibility, even more than conventional construction. http://bensonwood.com/innovation/index.cfm

Plumbing should be kept out of exterior walls anyways and as for wiring after the fact, keeping conduit to the interior and not opening up the exterior envelope is good for both SIPS and conventional walls. They typically offer more accessibility and flexibility than log and timber structures in my experience. Many cold climate builders work to keep all mechanicals inside the building envelope to avoid having it compromised by future inhabitants.

Oh and Sean, never install foam on the outside of SIPS. Maybe a more permeable insulation like Mineral wool but this complicates one of the best practices for SIPS; having a ventilated air space between them and the roofing or cladding.

Hey Brian,

Good stuff to discuss and debate as usual between us...)

It would be good for us at some point to start a Post thread entitled "Green Building and its two sides," or something like that. There is a big difference between what you promote in highly thermally efficient but very technologically and industrially dependant architecture, and what I do. I guess that kind of breaks it down right there.

Natural Green Architecture:

A structure that is 80% or more generated by local resources that come from the local environment or within a relatively short distance.

Zero, or extremely limited need for electrical-mechanical systems that are not also created on site, or in proximity.

Zero or extremely limited need for outside technology, or industrial manufacture support of any kind.

Highly thermally efficient.

Proven longevity as the systems are "inside dependent."

Industrial Green Architecture:

A structure that is 80% or more dependant on resources from outside the area, and manufactured by industry.

Highly depended on technology and industry to function mechanically and for maintenance of systems and structure over time.

Highly thermally efficient.

Questionable longevity as the systems are "outside dependant."

Now for the nitpick.. I dont think every home requires an HRV but I do feel every new home should be built tight enough to require mechanical ventilation. This might fall into the nitpick zone or it might be a fundamental difference between natural focused builders and more high performance "modern" builders.

Another difference between the two types of "green" architectural systems.

I think most natural builders see the benefits of mechanical ventilation and are beginning to include it.

I don't think I, or any reader of permies, would agree with that Brian. If you took 100 homes built within the format of "Natural Green Architecture," less than 20% would have, want, or need a HRV systems. They are just not part of the "Natural Green Architecture" building modality.

I fail to see the difference between "airtight" and "draft proof". If a home is not getting fresh air from outside then the air inside is not as healthy as it could be.

Come on Brian, we have covered this one before. The difference is simple. Without your HRV system working (which the don't when the power goes out,) when all the doors and windows are closed, a "Natural Green Architecturally designed" house is like having your head inside a sweater, and in a "Industrial Green Architecturally designed" house it is like having your head in a plastic (or Tyvek) bag.

The current debate between Indoor Air Quality experts and building scientists is how much CFM of outdoor air introduction is ideal.

Agreed, and most that I am following and reading are leaning toward the fact that well built/maintained vintage architecture was much more efficient than was once thought, with the air demands for the structure being more than met by simply ingressing and egressing the structure.

A "draft proof" home with no mechanical ventilation has no control over the situation other than opening windows which works great sometimes but not all the times.

It works just fine all the time, subjective view perhaps, but 10000 years of domestic design would seem to suggest otherwise, and we are not talking about the unmaintained or poorly built in this comparison.

As for SIPS, I agree that they can cause problems. I disagree that problems you may have encountered were products and installations done appropriately. Either the manufacturer screwed up or the installer did.

This one is not subjective, as I have serviced too many over the decades, and no matter what the manufacturer does, (or the installer) it will not stop rodents, ants, and other organisms from trying their level best from moving into the wall assembly wherever they can. That is just one of the many challenges over time, and the more time that goes on, the more challenges many of these homes are going to have in certain environments.

From my experience people have been more comfortable in their SIP homes and like them so much they insist on doing them again (even when I try to talk them out of it).

This could be very true, because even if the structure has issues, they are so well hidden within the internal structure, most folks don't even know they have a problem.

I also disagree that they are good for a contractors profit margin as they are usually not. Contractors avoid them because they are different. I don't think SIPs installers or GCs specializing in them are getting rich and usually it seems they are making less because they are passionate about energy use to the point of losing money.

If I was in error in this aspect it would be indicated in the market, which it is not. Panelized and stress skin system architecture is one of, (and in some areas) the fastest and most robust. So I stand by my observation, as the market is bearing witness to the truth of it.

I will also share that one of these manufactured home company representatives shared with me (and the wording is found within others companies internal documents.) give these homes a viable economic and functional life span of 20 to 30 years. I find that alarming, as it only supports the manufacturing industry, and the contractors that service them.

Your point about accessibility is fair but I would argue that in ways this is a good thing. Look at Bensonwood's open built model for the ultimate accessibility, even more than conventional construction. http://bensonwood.com/innovation/index.cfm

I know Ted personally and would not use his system as a good example for mainstream building modality. Very expensive to build for the average consumer, (not even possible to own by most) and out of context. Certain aspects of the system are well designed, while others are not. (this is subjective on my part as we have a history that goes back 30 years.)

Plumbing should be kept out of exterior walls anyways and as for wiring after the fact, keeping conduit to the interior and not opening up the exterior envelope is good for both SIPS and conventional walls. They typically offer more accessibility and flexibility than log and timber structures in my experience. Many cold climate builders work to keep all mechanicals inside the building envelope to avoid having it compromised by future inhabitants.

Agree in the general premise, but you still have wiring in most exterior walls and that reality must be accommodate for (regrettably.) You need more experience in well designed log and timbered structures as running mechanicals in them (particularly timber frames) is not a challenge at all if planned for. I would also add that modifing and augmenting is also much easier in "system designed architecture," no matter what the frame work.

Oh and Sean, never install foam on the outside of SIPS. Maybe a more permeable insulation like Mineral wool but this complicates one of the best practices for SIPS; having a ventilated air space between them and the roofing or cladding.

Cold roofs and rain screen walls that work in concert with each other are paramount in good modern design. Whether you clad the outside of a structure in 1" or 10" of foam have little bearing on that, as in either case, the Cold Roof and Rain Screen will still be designed for the outside of the architecture. WE definitely agree about the Mineral Wool insulation, as I am moving further and further away from foams and only toward more inert and/or natural insulative systems. Foam has its place but I am always looking for methods to avoid its application if possible.

JC Whitecloud, for some reason your posts double post are you double clicking the submit button?

I honestly find the debate in this thread is interesting but overall pointless. "Green Building" is great, I'm all for old ways and new ways. Honestly I'm mostly for the best ways. There is a ton of wisdom to the way things were done in the past and frankly a lot of Stupid practices as well. We have come a long way in the industry over the last 30 years but as always the problem is that one size does not fit all.

Right off the hop I gotta say profits are a non issue. When building you need to do your due diligence (most don't) and choose the best option for you. If that option includes someone making money and you getting what you want at a price you're willing to accept then who cares both parties win. We all need to develop an increase to survive and if that means you do it by gardening and barter then thats how you do it, if you charge people fee for service or goods then so be it. I know a lot of contractors and none of them are getting stupid rich of anything they do, the market really determines pricing. Not all are bakers or shoe makers, anyhow rant over.

I've done a lot of research over the last couple years on "Green Building" and I have a good bit of trades experience. I'm totally sold on better buildings and am very keen to put my money where my mouth is with my own build. That said I could really use specific responses. If there is a better more home grown way to build anything I'm game.

There are a ton of cool options for building. There is a newly completed earth ship near us and I really like the concept the owner/builders paid a fortune for the plans which had zero real local climate input and were drawn with what looked like pen. Is that green? I could have a architect with local knowledge draw me up a set of custom drawings for less then half of the cost of the one size fits all climates earth ship drawings. Whats important to me is performance of the building envelope. Your typical house should stand for 100+ years and if your burning a ton of fuel be it wood, gas or electricity to keep the place warm the impact over 100 years is way more then the impact of EPS or some other foam insulation. So in some climates further south, a cob house that relies on simple thermal mass to be comfortable would be an energy vacuum here in central Canada, plus the cold spots etc would make it really uncomfortable to live in.

I've looked at straw bale and I really like the concept, problem is that in order to hit the efficiency of near net zero heating that I'm looking for we would need to have a double bale wall and still a super insulated foundation/roof using a non natural product. Walls would be like 3.5' thick which is starting to verge on castle living. I've looked at cord-wood which I REALLY like but again I'd need to use super thick walls with a double run setup, super insulated foundation/roof and the labor input is extreme just for the walls. Labor costs even if they are my own have value. Simply using thermal mass doesn't work in my climate, you get a nice summer place and an ugly winter place, most people have no idea what -50C with windchill is like on a building let alone a human body.

So if you have an alternative that will work and not require an HRV then PLEASE explain. Actually if you have any really viable options I'm here to be sold . I am very much interested in affordable options that work in our climate, our buildings here are a mess, either old and hugely expensive to heat or new and badly built. There is so much good out there that just isn't being properly translated to the average Joe because of poor communication and a failure to address social realities. So if you don't mind the banter about ideals is great but we need real workable solutions.

I honestly find the debate in this thread is interesting but overall pointless. "Green Building" is great, I'm all for old ways and new ways. Honestly I'm mostly for the best ways. There is a ton of wisdom to the way things were done in the past and frankly a lot of Stupid practices as well. We have come a long way in the industry over the last 30 years but as always the problem is that one size does not fit all.

Sorry if Brian and I detracted from your query or that you found no value in them, and pointless. "Best way," is relatively subjective depending on your architectural values, financial abilities and/or skill sets in design and constructing the architecture you desire. Since I have spent over 35 years examining, documenting and disassembling vintage architecture I would have to disagree that much of what our forebears did with the resources they had could be called "stupid practices," in any way. Perhaps misunderstood by the novice observer, or not applicable to current building modalities, but I would seldom if ever cal them stupid. I have seen very little actual long term improvement in the domestic housing market, other than from a corporate or highly technical perspective. The ability to last even a single century for many of these homes is going to be a major challenge.

I know a lot of contractors and none of them are getting stupid rich of anything they do, the market really determines pricing.

If profit does not bother you and you get what you want, then that is a good thing. Most of the clients that can afford my services, typically do not care about profits either, only getting a structure that meets their architectural needs, goals and desires. I also know alot of contractors and developers, and I would say they are anything but stupid and most are very wealthy from their style of development, though that is currently shifting rapidly as the consumer public demands more for their dollar spent, and will not tolerate some of the old GC practices of doing business. I provide my guidance here on Premies free of charge for those that may not be able to normally afford consultation fees, in some cases I even help in person. You are more than free to hire me and I will charge you for the work that I do, as I am sure Brian would as well.

I'm totally sold on better buildings and am very keen to put my money where my mouth is with my own build. That said I could really use specific responses. If there is a better more home grown way to build anything I'm game.

I thought my recommendations in my first entry to your post provided as specific an answer to the level of questions you had asked, sorry if I failed at that. To address them more specifically, you are going to have to choose one of the myriad of building systems you have shared an interest in and ask very specific questions about them, otherwise the best I can do is generic answers.

There are a ton of cool options for building.

Yes there are, and if you chose one that you are considering over others we can discuss it.

Your typical house should stand for 100+ years and if your burning a ton of fuel be it wood, gas or electricity to keep the place warm the impact over 100 years is way more then the impact of EPS or some other foam insulation.

The architecture our group facilitates should last much longer than just a hundred years, and considering that some of the frames we use are already 250 years old, 100 more is nothing. Good architecture that is well designed should last well over 500 years, and 1000 is not unreasonable. As for thing like EPS foam, there longevity past even 50 years is in question considering there many environmental pitfalls, EPS foam is what we used in the lab to raise carpenter ants, and I have seen more than my share of wall voids hollowed out of the material by the invasive "wee-beasties" that like to borrow through it.

So in some climates further south, a cob house that relies on simple thermal mass to be comfortable would be an energy vacuum here in central Canada, plus the cold spots etc would make it really uncomfortable to live in.

That would all depend on the design of the cob house and its facilitation, if you had the work force, time and/or money, you could build a very thermally efficient cob house, though I agree I would not generally recommend it for your region.

Simply using thermal mass doesn't work in my climate, you get a nice summer place and an ugly winter place, most people have no idea what -50C with windchill is like on a building let alone a human body.

You have now mentioned straw bale, kubbhus (cord wood), and a few others, all it would seem do not meet your needs do to the required wall thickness. I would have to disagree with you about the efficiency of thermal mass walls, which is the principle of log architecture. I have help build and visited many of these types of homes, as far north as nearing the Arctic circle, and if well built and facilitated, they present as very efficacious during the long winters. This is especially true if the designs are augmented with additional thermal insulation like a mineral wool, of straw bale/kubbus mass. You are going to have to either use super efficient (and expensive) foams or other modern materials to obtain a "net zero," or even super efficient passive house, if you do not want walls thicker that 400mm to 600mm.

Affordable is a relative thing, as any of these super insulated homes are going to cost much more per square meter than average architecture. Since you do not even have a design modality selected yet we do not even need to discuss the applicability of HRV or any of the other details until you do. Some of your design interests may actually require an HRV system as Brian has suggested, while others may not.

If you want a recommendation for a choice after reading some of your views, I would suggest a Kubbhus of straw bale with timber framed superstructure. and a simple single floor design no greater that 180 square meters (~2000 sq ft.) This can be expanded or contracted depending on needs and budget. What ever you do you can expect to spend a minimum of $1600 per meter squared(~$150 per foot squared) for your suggested design goals.

Regards,

jay

Sean Rauch wrote:

-We live in Manitoba Canada and plan to build just outside of Winnipeg

http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/International/pvwattsv1_intl.cgi says 3.13 kWh/m^2 (992 Btu/ft^2) of sun falls on a south wall on an average December day in Winnipeg.

The stat file at http://apps1.eere.energy.gov/buildings/energyplus/cfm/weather_data3.cfm/region=4_north_and_central_america_wmo_region_4/country=3_canada/cname=CANADA says the average December temp is -14.1 C (6.6 F) with a -12.1 high.

-I'm working with a model right now that has 2000 square feet of living space spread out over two floors

... eg 32'x32'x16'-tall, with a 1024 ft^2 ceiling and 2048 ft^2 of walls.

-We're planning the basic south facing windows with thermal mass inside to collect as much winter sun as possible.

That could work. If the house has no internal heat gains and it's 75 F on an average day and 65 after 5 cloudy days in a row (with a 2^-5 probability), 65 = 6.6 + (75-6.6)e^(-5x24/RC) makes time constant RC = 759 hours. With US R30 walls and an R60 ceiling and R30 night- and cloudy-day window insulation and a 1/R = G = 1024/60+2048/30 = 85 Btu/h-F cloudy-day conductance, it would need C = 759hx85Btu/h-F = 64.8K Btu/F of room temp thermal mass, eg 64.8K/25 = 2591 ft^3 of concrete or 4048 ft^3 of cylindrical rock gabions, about 25% of the house volume, or more, with less night window insulation.

-The house wont be off grid but I don't want to rely on the grid for any of the climate control demands of the house.

It might have a shiny massy ceiling heated by passive air heaters, with a thermostat and a slow low-power ceiling fan to mix down hot ceiling air as needed to keep the house exactly 70 F for 5 cloudy days, or 70 F during the day and 60 at night. Here's a nice air heater: http://www.builditsolar.com/Projects/SpaceHeating/solar_barn_project.htm With hot ceiling air and colder air outdoors, you might use R2 twinwall polycarbonate with 80% solar transmission instead of a single layer in balmy Montana. Gary Reysa and I tried this scheme in 2010, with one big mistake, an uninsulated partition wall that turned the air heater into an air cooler at night... http://www.builditsolar.com/Experimental/dCube/Barra/BaraBox.htm

With no windows (use flat screen TVs and outdoor cameras), the house would need about (65-6.6)85 = 5K Btu/h or 119K Btu/day (collect 20K Btu/h for 6 hours) or 596K Btu for 5 cloudy days in a row. At (say) 160 F, a 1 ft^2 twinwall air heater would gain 0.8x992-6h(160-6.6)1ft^2/R2 = 460 Btu on an average day, so the house could have 119K/460 = 260 ft^2 of air heater glazing, eg an 8'x32' south wall. A 1024 ft^2 ceiling with a 3 Btu/h-F-ft^2 slow 2-sided airfilm conductance would be about 20KBtu/h/3KBtu/h-F = 7 F cooler than the hot air around it when collecting heat on an average day, and a 5.5"x32' air heater flow path with A = 14.7 ft^2 and H = 8' would make the air heater air (20K/(16.6x14.7sqrt(8)))^(2/3) = 9.4 F warmer than the air near the ceiling, so the ceiling would be 160-9.4-7 = 144 F on an average day.

A 1000 cfm ceiling fan could keep the house 70 F with a 70+5KBtu/h(1/3K+1/1K) = 77 F ceiling, and (144-77)C = 596K makes C = 4.3K Btu/F for 5 cloudy days in a row, ie 4.2 psf, eg 0.8 inches of water, or deeper water in trays that cover less ceiling area.

Have fun :-)

Nick

Nick Pine / The 'Permies Cloud' : have you seen the Kalwal and Lumira Aerogel window panels from> www.kalwal.com/aerogel.htm ?
And there are Evacuated(actually low pressure) Aerogel panels at very high R-50 ! Love to see them on the outside of a 'Rain Wall' ! BIG AL

allen lumley writes:

>... have you seen the Kalwal and Lumira Aerogel window panels from> www.kalwal.com/aerogel.htm ?

They look expensive, with 22% solar transmission, compared to $1.30/ft^2 twinwall from my local greenhouse supplier (Nolt's Produce in Leola, PA.)

Nick

nick pine wrote:allen lumley writes:

>... have you seen the Kalwal and Lumira Aerogel window panels from> www.kalwal.com/aerogel.htm ?

They look expensive, with 22% solar transmission, compared to $1.30/ft^2 twinwall from my local greenhouse supplier (Nolt's Produce in Leola, PA.)

Nick

Yes, but they are R-20!!!

I wanted to make my whole roof out them until I saw the price. I still might if I build my retirement studio.

Sean Rauch wrote:

-We're planning the basic south facing windows with thermal mass inside to collect as much winter sun as possible.

> That could work. If the house has no internal heat gains and it's 75 F on an average day and 65 after 5 cloudy days in a row (with a 2^-5 probability), 65 = 6.6 + (75-6.6)e^(-5x24/RC) makes time constant RC = 759 hours. With no air leaks or floor heat loss and US R30 walls and an R60 ceiling and R30 night- and cloudy-day window insulation and a 1/R = G = 1024/60+2048/30 = 85 Btu/h-F cloudy-day conductance, it would need C = 759hx85Btu/h-F = 64.8K Btu/F of room temp thermal mass, eg 64.8K/25 = 2591 ft^3 of concrete or 4048 ft^3 of cylindrical rock gabions, about 25% of the house volume, or more, with less night window insulation.

A 1 ft^2 R2 south window with 80% solar transmission and an R28 shutter (6" Styrofoam inserts that double as tables for 6 hours per day?) would gain 0.8x992-6h(75-6.6)1ft^2/R2 = 588 Btu/day, so you could heat the house with about 119K/588 = 202 ft^2 of such windows.

Windows with weighted insulated R3 curtains rolled up every morning by a solar panel driven 12v motor and then released when the sun went down would gain 588-18h(75-6.6)1ft^2/R5 = 342 Btu/day, so you could heat the house with about 119K/342 = 348 ft^2 of them. On a cloudy day, with the windows shuttered, the house conductance would be about 1024/60+348/5+(2048-348)/30 = 143 Btu/h-F, so it would need C = 759hx143Btu/h-F = 108790 Btu/F of room temp thermal mass, eg 108790/16 = 6800 ft^3 of cylindrical rock gabions, about 42% of the house volume.

A ft^2 of R4 south windows with 50% solar transmission would gain 0.5x992A = 24h(75-6.6)(1024/60+A/4+(2048-A)/30) Btu/day, which makes A = 998 ft^2 (eg a 16'x64' south window wall on a 16'x64'x16'-tall house) with G = 1024/60+1024/4+(2560-1024)/30 = 324 Btu/h-F, so it would need C = 759hx324Btu/h-F = 246118 Btu/F of room temp thermal mass, eg 246118/16 = 15382 ft^3 of cylindrical rock gabions, about 94% of the house volume.

With no shutters, A ft^2 of R2 south windows with 80% solar transmission would gain 0.8x992A = 24h(75-6.6)(1024/60+A/2+(2048-A)/30) Btu/day, which makes A = 5090 ft^2...

Nick

Mr Ken Koch wrote:

>Come on Nick! Where is the optimism factor?

As an optimistic alternative, the Winnipeg house could have R32 SIP walls and an R48 roof with a 1024/48+2048/32 = 85 Btu/h-F conductance and a frugal 300 kWh/mo (1421 Btu/h) of indoor electrical use and a 6.6F+1421Btu/h/(85Btu/h-F) = 23.3 F effective outdoor temp (see how nicely the units work out?), so it would only need 24h(70-23.3)85 = 95.2K Btu/day of solar heat.

At 80 F, a 1 ft^2 twinwall air heater would gain 0.8x992-6h(80-6.6)1ft^2/R2 = 573 Btu on an average December day, so the house could have about 95.2K/573 = 166 ft^2 of air heater glazing, eg an 8'x20' south wall.

An 8500 Btu/F 4"x1024ft2 radiant floorslab and 7K Btu/F of walls and furnishings would make time constant RC = 15,500Btu/F/(85Btu/h-F) = 182 hours. If the house is 72.3 at 3 PM on an average December day, it would be 23.3+(72.3-23.3)e^(-18/182) = 67.7 F by 9 AM the next morning, with no water flow in the floor.

On a cloudy day, with a 1Btu/h-F-ft^2x1024ft^2 slow airfilm conductance in series with a 1000 Btu/h-F 2 gpm water flow conductance, the floor could provide (70-23.3)85 = 3970 Btu/h of house heat with 70+3970/2000 = 72 F water.

The house needs 5x24x3970 = 476K Btu for 5 cloudy days in a row, eg a 476K/(140-72)/62.33 = 112 ft^3 tank cooling from 140 to 72 F, eg a 4'x10'x3'-tall plywood box with a 10'x16' folded EPDM liner or a 4'-tall x 6' diameter tank with 132 ft^2 of surface.

With R20 insulation, the round tank would lose 24h(140-70)132/20 = 11.1K Btu on an average December day. We could keep it 140 F with a separate 29 ft^2 twinwall air heater and a 1000 Btu/h-F car radiator and a 1000 cfm fan and a 2 gpm pump, or timeshare a slightly larger basic house air heater or a smaller deep-mesh air heater http://www.builditsolar.com/Experimental/DeepMeshCol/120116Test.htm

A larger air heater and tank could also provide hot water for showers.

Nick

Hi Sean I also live in Winnipeg. Passive solar or active solar. Both systems have a contribution for your application. In this climate definitely a glycol closed loop system for the active side, you don't want freezing.

We are thinking both.

Very nice. Let the sun shine. I am mulling over plans for straw bale, certainly labour intensive. My hope is this might eliminate the need for summer cooling. I like the rocket heater and planning to build one.

One of the consultants I work built exactly that southwest of the city just outside the perimeter.

Hey friends,

A classmate of mine is building a house, I just found out, and is 2 or 3 weeks to completion. This is in Boston, zone 6 or or 7+/-10 depending on the day (thanks global weirding). And I love the idea of passivhaus construction being something that seems pretty well established now and accessible to someone not yet on the permy bandwagon, but there's a lot of synthetic and, it appears, toxic building materials involved in this.

So, given that there's more to wade through than even I have time for, what should I tell her? anyone know a person she could consult with who could do something helpful at the 11th hour? someone who would educate her about the issues for going forward, maybe a future retrofit? she is open to change, intelligent, and has respect for my opinion, so I think it's a good opportunity to carry a message/infect hearts and minds.

Any suggestions most welcome.

Also, she and her husband are originally from the Dominican Repermies, in case that's important. I imagine they want to be really, really warm, for instance, not just New England warm.

Thanks!

J

I would strongly recommend looking into climate battery, passive annual heat storage, annualized geosolar, annualized thermal inertia. There is an entire subdivision built somewhere within a province or 2 of you using this principle for all its winter heat., and a geoff lawton video about a large greenhouse somewhere in northern bc using the principle. the basic principle is store the solar heat from summer in a huge thermal mass in the ground and use it to heat in winter. this is accomplished either passively or actively. there are hi tech and lo tech approaches, but well worth investigating, as even the hi tech approaches should not represent a very big cost increase per square foot.

another term 'seasonal thermal energy storage'
https://en.wikipedia.org/wiki/Seasonal_thermal_energy_storage

also
https://en.wikipedia.org/wiki/Drake_Landing_Solar_Community

http://www.norishouse.com/PAHS/UmbrellaHouse.html

http://permaculturenews.org/2015/01/09/how-to-build-a-geo-solar-greenhouse/

Maybe I am just a dumb yuppie...

Why don't you put the rocket stove as close to the intake as possible, then combust whatever comes in and use the stove to heat the same mass as is your primary source. You'll probably have some reduced efficiency but when I think secondary I think primary is broken, not working, or I don't wanna.

I remember when I worked the big HVAC industry they had a heat exchanger which reminded me of the DPF on a big CAT engine, intake goes N and S, outlet goes E and W for example please rotate to fit your need .If you are worried about your intake/outtake freezing why not do the same thing, light it on fire... Basically what the, "Fast Cat Light Off," is refering to is, the filter is clogged, we are going to douse with some accelerant and light the filter. Generally the manufacturer doesn't want the user loading the engine as this could result in an afterburner due to a raise in intake pressure.

Why not do this same thing but maybe use a bonfire and have a clean out underneath your heat exchanger? Then you can skip the electricity minus whatever additional cleaning is required.