Image Credit: Kent Earle
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Editor’s note: Kent Earle and his wife, Darcie, write a blog called Blue Heron EcoHaus, which documents their journey “from urbanites to ruralites” and the construction of a superinsulated house on the Canadian prairies. GBA first posted a blog about their decision not to seek Passivhaus certification in May 2015.
The biggest question mark for us up to this point was, “how the heck are we going to heat this place?”
First, we should list a few conditions and limiting factors.
We had no natural gas to our site. This is probably a moot point anyway because even if we did have ‘natural’ gas we would not have used it. We did have a neighbor ask us if we would consider bringing it in. But this just seemed ridiculous. For a cost of $20,000 you can pipe in a non-renewable resource and then pay monthly fees for it for as long as it is available, and given the rising energy prices this cost is only going to go up and up.
We do have grid electricity at our site, but we intend to be net-zero or net-positive if possible. The power delivered to our site comes from the Queen Elizabeth power station which is a natural gas-burning. This is a big reason why people in places where you “must” choose from grid-tied power (which is often still coal) or ‘natural’ gas, select the apparent lesser of two evils and choose natural gas for heating/cooling and for appliances.
Still, there is a third option that people seem to forget: solar power! For less than or equal to the cost of bringing natural gas to our site, we can put solar panels on our roof with a battery and generate not only our own electricity for heating, but also our own power for running everything else in the house.
We are putting in a wood-burning stove as a backup heat source. Now, I know Passivhaus purists think that this is a bad idea and Wolfgang Fiest, the Passivhaus guru in Germany, has outright said that there are no wood-burning stoves that meet Passivhaus standard, but we don’t care. I know of nothing more comfortable than sitting next to a crackling fire. Also, wood is considered to be a renewable resource: cut down a tree for fire and plant a tree in its place. (I’ll write a separate post about wood-burning stoves later).
OK, so now that we have those issues out of the way, there were still huge decisions to make. Over the past few months I’ve read innumerable articles on heating options for northern climates in general and superinsulated houses in particular, as well as received everyone else’s biases on the optimal heat source. What I realized is that there are many different options and all of them have pros and cons.
The minisplit route
Most Passive Houses that I read about used a ductless minisplit heat pump, and the majority of these seem to be made by a Japanese company called Fujitsu. These are pretty cool little devices.
In a Passivhaus, the heat load is so low (usually between 10,000 to 15,000 BTU/hour — as an aside, most standard furnaces are 60,000+ BTU/h) that usually two of these little systems are sufficient for heating a 2,000-square-foot house with ease.
As the name implies, they do not use any ductwork, and essentially function like a space heater mounted on the wall. There is a pipe with refrigerant that passes through the exterior wall to an outdoor unit that draws air in, extracts heat from that air, and delivers a hot fluid (refrigerant) to the indoor unit. In the moderate climates of Asia, Europe, and the U.S., these are great. A major appeal is that in the summer these units act in reverse, providing air conditioning. In a northern climate like Saskatchewan, though, these are likely not the best option.
Previously these units would operate when the outdoor temperature was as low as -5°C (23°F). Fujitsu has recently come out with a new model for “extreme low temperature heating,” which will heat when the outdoor temperature is as low as -25°C (-15°F). Unfortunately, this is not sufficient for our cold Canadian prairie winters. Last year we had a record number of cold days for the winter: 58 days of -30°C (-22°F) or colder. A couple years ago for the entire month of December it did not get above -25°C (-13°F) for a high! There will be days, every year, when it is -50°C (-58°F) in the morning. That is insanely cold. If you have never experienced cold like that, it is really something to behold. Fujitsu would have to come out with a “Super-Duper Ridiculously Extreme Low Temp Heating” minisplit to cope with that, I’m afraid.
If we were to use the minisplit system then we would need to have backup heat sources in each of the rooms of the house, such as radiant wall panels or baseboard heaters. Although these are relatively cheap at less than $100 each, I must admit that I think they are ugly. Super ugly. Even the fancy ‘modern’ ones are ugly. I know, that shouldn’t be one of my criteria, but it is, I’m extremely particular and I think they’re ugly and cheap looking. And I think the minisplits are ugly too! Gah — the truth comes out.
You see, we like minimalism. Our house was going to be simply designed: no casing around doors and windows, no crown molding, no baseboards. Adding baseboard heaters just seemed like a mortal sin to my minimalist aesthetic.
Then there’s electric heat
Another option that was brought forward was to use an electric-resistance heating coil. Basically how this worked was like a typical forced air ducted system, but a little bit different. A no-brainer, must-have appliance for an airtight house is a ventilation system. If you don’t put one of these in then you are going to have serious problems from moisture build-up and air quality. We had already decided that we would use a Vanee HRV (this was developed by Dick Vanee through the University of Saskatchewan, who is credited with developing the first widely available and mass produced HRV system) in our place, which as with all other ERV/HRV systems, uses ductwork to each room or area of the house to deliver fresh air and draw out stale air.
Here’s how the heating coil works: It is mounted in the mechanical room in the supply air duct, thereby preheating the ventilation air before it is distributed to the house. The cool thing about this is that you can use the ductwork already present for the HRV system. This approach only works in a superinsulated house; in a conventionally built house you would need separate ductwork. For this reason, this approach leads to the claim by some that in Passive Houses, “conventional heating systems are rendered unnecessary throughout even the coldest of winters.” (This is a fairly misleading statement, as the suggested approach uses the pre-existing ventilation system to distribute space heat.)
There are a few downsides with this system, however. The longer the ductwork, the greater the heat loss prior to reaching its end point. We are a building a long narrow house and have one length of wall that is 48 feet.
Second, this is basically a forced-air system. An HRV flow rate is a lot less than a true forced-air system, but essentially you are just heating the air, not surfaces as is the case with “radiant” heat.
Third, this system cannot be well controlled. It is one system for the whole house. So in our living/dining room and master bedroom that get more solar gain, they would also get the same air heating, which could lead to overheating concerns.
Fourth, we would likely still need to supplement the system… and we’re not going to talk about that again.
The radiant floor option
A lot of conventional builders, and I’ll say “lay-people,” suggested in-floor heat. Actually they said if we didn’t use in-floor heat then we were idiots. OK, they didn’t quite call us that, but I felt their judgment. In-floor radiant heat is certainly appealing for a lot of reasons.
We planned to install a 1 1/2-inch concrete slab topper on the main floor of the house for passive heating purposes as well as the required 4-inch slab for the basement. And we also really like the aesthetic of nicely finished concrete floors (remember we are modern minimalists). But there was one problem: concrete floors are cold. When we told people that we might not use in-floor heat in the concrete, this is when their judging eyes showed themselves.
Second, in-floor heat is very comfortable without a doubt. We have several friends who have in-floor hydronic heat and walking into their house and feeling the warmth in the winter is very pleasing.
Third, you don’t actually see the heat system. It is embedded in the floors. No wall panels, no horrendous baseboard heaters.
Fourth, it can be zoned and controlled. Each room can have a thermostat installed individually with piping running specifically to each room with a sensor in the floor that allows for it to be controlled. This was a big bonus, because rooms like the mater bedroom and living/dining room do not need as much floor heat because the thermal mass and solar gain will heat these areas, whereas the north rooms and hallways do not have solar gain so would need to have a higher floor temperature.
OK, so you can begin to see where my bias was leaning. That is, until I started to read about radiant floor heating in superinsulated and well-built houses. (For links to some of these articles, see the “Related Articles” box above).
Too much heat for a not-so-crappy house?
Damn. The basic argument was that radiant in-floor is nice and makes sense in crappy houses. I don’t want a crappy house! Also the general agreement was that these systems were overkill. Passivhaus is called “passive” for a reason: the idea is to reduce the use of non-passive, mechanical systems. The heat load of 10,000 to15,000 BTU/h does not require a big system including a boiler, pump, and in-floor piping. In fact, when we talked to a couple friends who had built well-insulated houses with passive solar orientation, they told us that overheating in the winter did happen and they would have to open their windows in the dead of winter. This seemed crazy!
I had no straight answer and everything that I read either did not seem appropriate for our climate’s peak loads (coldest times of the year) or was apparently overkill. Sleepless nights were the result.
However, as I talked to others in the Passivhaus field, they admitted some problems with the Passivhaus model for a northern climate with frigid temperatures like ours. Passivhaus was really designed for moderate climates in Germany and a lot of the articles I had read were discussing moderate climates in the U.S.
Indeed, radiant floor heating would be overkill for those climates, but those climates do not get down to extremely low temperatures like ours.
Discuss options with the team
It was decided that the best means to make this difficult decision was to sit down as a team and discuss. We had a meeting with our team of four engineers, all trained in LEED building, one with Passivhaus certification and one with R-2000 (and extensive energy modelling) experience, along with the mechanical contractor and Darcie and I. We went through and made a list of advantages of each system — which essentially is what I wrote above.
In-floor hydronic heating was the clear winner.
All of my questions about setting up this system and my concerns about overheating were alleviated in this meeting. We would use our PV system to power a simple, small, two-element, 100% efficient electric boiler by Argo. (We did briefly play around with the idea of an air-source heat pump hot water heater from Germany for both in-floor heat and domestic hot water, but due to the high capital cost and potential issues of no one knowing how to service it here, we canceled this idea. The thought still seems intriguing, however, and in another few years this may become the best solution. Check out this article for more information.)
On the domestic hot water side, we selected a fairly straightforward, 47-gallon Bradford White high-efficiency electric-resistance hot water heater. We also planned to insulate this with its own extra insulated jacket. Really, in the end, it came down what is the simplest, most cost-effective solution to meet our needs.
As for overheating, the engineers would design the system so that areas hit with solar gain would not overlap with those of the in-floor system, while those not receiving solar gain could be controlled separately to deliver us the best of both worlds. On the extremely cold days, our little Norwegian wood-burning stove would take the edge off.
Boom. Decision made. Now I could sleep again.
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15 Comments
Don't underestimate those mini-splits.
For the record, a cold climate Fujitsu keeps running at -30C and colder, putting out a decent amount of heat, just not a manfacturer-specified amount of heat. The efficiency at those cold temperatures isn't nearly as good as it is at -20C, but it's still beating resistance heaters. The seasonal average efficiency in a PassiveHouse would be about twice that of resistance heating in a Canadian prairie climate, and it WOULD make a measurable difference in the power use.
Combined with a heat pump water heater (to give it some load in the shoulder seasons) the net reduction in power use could be substantial, but whether it had a lifecycle cost advantage over just doubling the size of the PV array would require a careful accounting, and it's a moving target in the face of rapidly falling costs for grid-tied PV, and rapidly evolving policy support & incentives for installing PV.
Radiant floors and passive solar can work fairly well together without overheating the space, when the tubing runs in north-south loops going from the rooms with the solar gain to those without. You don't have to skip actively heating those rooms with the floor.
heating with a space heater
I am in Iowa with hot, humid summers and cold dry winters. I have been retro insulating a 1950s Cape Cod and have about R-90 at the very peak of a gabled roof, and R-50 the rest of the roof and 75% of the walls of the first floor.
I removed the central air conditioner this summer and used two 5,000 BTU window units, one for each floor. The units had to run 24 hours per day to get rid of the humidity, outdoor temperature 95 degrees F with indoor temperature 65 F.
For heat I am using a space heater at 750 watts, which can increase to 1500. So far so good, so will be removing the furnace. Insulating takes up space, but removing the central air conditioners and using a $10 space heater and a couple window units does free up indoor and outdoor space.
I am willing and glad to experiment and tolerate moderate temperature differences so am satisfied to go this route.
We came to the exact same conclusion
Great article! Building a 1200 s.f. well-insulated house in Northern Ontario this summer, we went through the *exact* same process and reached the same conclusions. We originally planned to go with a mini-split paired with baseboard/cove heaters, but hated the aesthetics of it (we also went very minimalist) and were worried about cold concrete floors and uneven (room to room) heating. Instead, we embedded PEX in our concrete slab (the concrete is our finished floor) and are heating it with a little 7kw electric boiler. It was surprisingly affordable and has proven to be incredibly comfortable so far. The one room without floor heat (the mechanical room) is uncomfortably cold on the feet (even though the slab is well-insulated), so I think we made the right choice. We have had no problems with overheating--it has been extremely even. We also have a small wood stove for backup, and to help keep our electricity bills down in the depths of winter. Anyway, floor heat has been much maligned lately, but I do think it still has a place, especially here in Canada.
A 3/4 ton PTHP would use half the power
Erich: In your climate replacing one of the window AC units with a package terminal heat pump (PTHP) would free up a window, and would use half the power for space heating. It's more than $10, it may still have a reasonable ROI on energy use savings, and is well under the cost of a 3/4 ton mini-split. As a DIY you can install one for under $1000.
The Amana DigiSmart PTHPs even come in a 7000 BTU cooling flavor as well as bigger ones (9k, 12k and IIRC even bigger). The 7K unit puts out about 6800 BTU/hr in heat pump mode at average Iowa mid-winter tempertures, which is about the same amount of heat as a 2000 watt space heater, and it has a backup resistance heater if it can't keep up in heat pump mode. The 9000 BTU/hr unit puts out about 8000 BTU/hr in heating mode.
A 7000 or 9000 BTU DigiSmarts run $700-800 at internet pricing, throw in another $100 for the wall-mounting sleeve and another $50-100 for the circuit breakers & wiring. Even if you're only spending $500/year on heating with a space heater, the ROI is still pretty good for a PTHP in a zone 5 type of climate. (Not so much in Canadian midwestern coolth though. They autotomatically switch to resistance heating when it drops below -5C, but run the heat-pump at temps above that.)
Hope you are sleeping well.
I had quite a smile on my face...I suppose of self recognition, as you made your way through the spooky forest of choices for your bitchin' cold climate house. I am in a similar climate, no that is not true, hardly anywhere outside of Manitoba is similar to Saskatchewan. (Inside Canadian joke). I think you made some good choices. Although Dana Dorsett has defended the air source heat pump, he is somewhat hesitant when it comes to the ROI. I can assure you the Roi will never pay for itself over the lifetime of heat pump when compared to the same investment in PV. The cop is barely above resistance heater for 3 months of the year. Then your solar kicks in in the shoulder season and the heat pump is not needed just when it would actually have a decent cop! I think you did well and can sleep soundly. Perhaps the only comparable reference to your HDD is Thorsten Chlupp up in Alaska with his 14,000 HDD. His solution was seasonal storage in water (5000 gallon indoor tank) heated by solar in the 3 seasons the sun actually shines, and supplemented with masonry stove and insulated exterior window shutters. In your latitude the solar is not bad through the winter in Sask. If you had a nice in ground super insulated 10,000 gallon tank you would probably get close to zero electric demand. Of course its all a hobby at this point, you are all ready economically and comfortably there with your choices.
We went the mini split route
We went the mini split route but it wasn't as effective as we'd hoped. Thanks for this post. Got some very helpful information here that I intend to put to good use.
PTHP
The DigiSmart states: "Extended Heat Pump Heating: Heat pump models will operate in the heating mode down to as low as 24°F outdoor ambient temperature."
I do have an interior portable heat pump, which has one intake hose and one exhaust hose. The heat pump is supposed to be used only with the exhaust hose, without an intake hose, but that depressurizes the house, causing outdoor temperature to be pulled in, so the house does not warm up in cold temperature. I plan to experiment with it to see how it works in cold weather with both hoses attached.
I expect the heat bill will be under $200.
The 11.7 EER of the DigiSmart for cooling is about the same as the under $100 air condiitioner's 11.1.
HP or not HP
Sounds like a great project. I would wonder if the economics of installing a radiant floor with an electric boiler is cost effective . If the floor plan and heat load lends itself to a mini-split, I struggle with the concept of using straight resistance heat as the primary heating source. Most mini splits will deliver about 60% of their nameplate heating output at the bottom end.Usually enough for a Passive design.
A mini-split also functions with minimal parasitic losses in distribution. Granted, it is allowing fringe areas of the home to be a bit cooler, but it is superinsulated, right?
I agree with the use of a woodstove. It is just nice to have if you need it. I am loathe to make holes in my buildings for things like flues, but that is the price to pay and I am willing to make it.
Good luck with your home!
Pond as the heat source?
If using a heat pump would there be merit in using a pond, or even well water (about 10 C in most of the prairies) for the cold end of the pump. You would need to lay insulated water lines to the bottom of the pond, but this would give you a source of 4 C water (Assumes pond depth of at least 15 feet. Alternately you could pump 10 degree water from your well, and drop colder water into your pond.
Backing up the backups
Heat distribution vs space BTU requirements vs BTU efficiency are always fun arguments to watch.
For all times it is not sub zero outside, a heat pump is always going to be able to deliver more efficient BTU than your electric strip heat (or hydronic heat pump.vs electric water boiler). The cost-benefit or payback of this more expensive system is up to the user and the situation. If you live in the arctic (and it sounds like you might!) then a heat pump has some serious competition from gas/propane/oil/electricity as far as cost per btu delivered over the lifetime of the unit... but for everyone else in more reasonable climate zones where you are above 10 degrees F these findings may not actually apply and a heat pump could still win by a huge factor...but...
Now, as another user commented and your article alludes to, if your superinsulated home only needs a 1500watt heater for 1 month out of the year, and you need no additional heat the rest of the year, the efficiency of the heat pump is moot if it wont pay for itself in savings over 20 years. Even if strip heat is 10x more expensive per btu delivered, but a fraction of the cost installed, the strip heat inefficiency per BTU is a moot point. This is a critical point to make and I am glad you have addressed it. I am unsure how to summarize this better.
My personal anecdote is that I use a mitsubishi mini split heat pump in climate zone 5 with a tropical 5,500 heating degree days at base 65F. Sure it gets down to -5 degrees every winter, but the pump can easily keep up and at a much higher COP than strip heating. On the worst days with sub zero temps and the wind howling they do struggle to maintain over 60F, but then again I live in a less-than-code-house built in the 1960s, not even close to a superinsulated house. Perhaps I should have spent that heat pump money on insulation instead (oh the loss of sleep continues!).
Of course those worst case blizzard situations are also when the power goes out, so no amount of electric backup anything would help. I am very glad you have a wood stove. I personally have a gas stove I can light with a match to keep things from freezing when the grid goes down. The lights go out and I start baking everything. Many solar systems no longer have this off-grid functionality, so always make sure you backup your grid heat source with something manual!
We have long bouts in the single digits here and it is tough, I cant imagine living in the arctic with -13F highs and -50+F lows! Goodluck out there and I believe you made the right choice for your climate!
Dana, PTHP and mini splits in such cold weather
PTHP... IMO suck!! Why? No way can I listen to one blow air.
Mini splits also blow air. For a superinsulated cold climate I like the idea of going with money spent on solar panels. Generac now sells whole house generators specifically designed for off grid.
Things are rapidly changing.
For me, I love the idea of reducing the need for power. And reduce it even more for when the sun shines less. At night, use LESS. WINTER USE LESS. Summer... use LOTS!!!
One of the main thing about myself is I found long ago that I am bored way to easily. So I am pretty darn good at almost all the trades. Why? Well it squashes boredom. So the idea of dealing with living in concert with the amount of sun energy available day verses night, summer verses winter is for me... FUN! and another way to combat boredom!!
Dana, PTHPs... make too much dang irritating noise imo. What say you?
Kent, great article and I concur with your choices. bravo for doing such do diligence.
UFH [Under-floor heating]
Some thoughts on UFH, I got it right the second time, my design, installation and living with it.
I installed hydronic UFH in my second home. Pex pipe in four inches of reinforced concrete, on top of six inches of polystyrene. This worked very well in the winter and indeed during most of the year, but some days it was impossible to live with. The problem, concrete takes forever to cool. On a typical morning the room is a comfortable 22C, you sit watching the birds in the snow outside your picture windows, then the sun comes out, suddenly the room is 50C or more. You are boiling, you can't breath, you run round opening windows.
Having learnt a lesson, my current home has pex pipe laid in the top of six inch thick polystyrene, with a light weight t&g OSB floor topped with fitted carpet. This holds little heat and responds quickly to temperature change. It is controlled by two wireless thermostats, one in the bathroom that controls the bathroom and bedrooms, the other in our dining room that controls the other rooms. Both can be moved anywhere in the home, the dining room one sits on our sideboard or on the coffee table by my seat. They control the air temperature, in which we live our lives. They are set at 22C and flick between 22C and 21.5, they control motorized valves and our natural gas modulating boiler. the temperature holds good at 22.3C for hours on end. The floor stays around 23 to 27C – the walls, ceilings at 22C comfortable to the point where you forget its cold outside. Of course the temperature still rises on sunny days – usually to no more than 26C.
Using a Weather Station complete with memory, attached to my computer I can monitor our room temperature 24/7. There is a discrepancy between the temperatures shown on the thermostats and those on the Weather Station, which is correct I don't know, but one showing 22C the other 22.3C I can live with.
Great Prroject
Great project folks! Just a couple of experiences we had.
We installed an almost identical system (we used an indirect water heater, piped into the hydronic system) in a house we built in Panorama Ski Resort a few years ago. It wasn't anywhere near Passive and not even close to Pretty Good. The climate was cold and winters long in a long narrow valley, where, when we saw the sun, was for about 4 hours a day. But the system worked very well (only issue we had with the Argo was that years after the install, the heat exchanger cracked causing a major leak in the basement), but the timing of turning on/off had be fine tuned for quite awhile. But all in all it kept the house toasty.
Fast forward a few years and we built an almost -passive in a mountainous region of Northern Italy. Temps to -15C in the winter, usually very sunny. We installed a hydronic system in a self -levelling compound. It was a complete waste of money! We have NEVER turned it on. The house performs so well with just sunlight (massive windows), great airtightness (ACH=.72) and massive insulation (R=80 in roof and R-60 in walls). Seriously, if we are cool, we plug in a 2000W space heater for a couple of hours, or invite some friends for dinner (or bake bread!).
So, yes it is indeed a dilemma. What to use for heating, and how much.
We are now on a new project in southwestern Ontario. We are taking an old Victorian (1902) and doing a complete energy retrofit. I have noticed that the vast number of "experts" are using software packages that are wholly unsuitable for a well insulated and tight house. My consultant was using the Carrier forced air software package, which doesn't allow a lot of "tweeking". He couldn't understand the concept of an ACH below 1.0! My experience shows that getting the right heatloss numbers is a major hurdle, but then once you have those, choosing the right system is a matter of personal taste (forced air, warm feet, electric vs. natural gas, and so on). In our case we are going to try a hybrid approach. We have decided to try using a ceiling mounted ductless minisplit (hidden in the floor joists) for AC and heat in the shoulder months (15K BTU units are around $1200 Canadian. They are not the low temp units, but should work well to -15C), and our "cold" weather heat will be hydronic (in slab in the basement and under joist for the remainder).
All the best and good luck!
Similar situation
I am currently building a 2 storey, 1200 sq ft home in the Yukon. I am going through the same situation with the heating. My goal is to achieve the highest EnerGuide rating as possible on a small budget.
I am planning an using a ductless minisplit but can't decide on the unit. The multi zone units are much less efficient and more costly to install. I'm considering 2 small units, one on each floor or just a single unit large enough to for the whole house, installed in the open kitchen/living/dining area.
For back up heat I will have a woodstove and an electric coil heater in the HRV supply. You mentioned the same design with the HRV heater but still requiring back up heat in each room. Did you consider using in floor electric heat to avoid the "ugly" baseboard heaters? Probably a much cheaper choice than the hydronic radiant heat.
I'm interested in hearing about your approach to achieving the low ACH.
Heating in a cold climate - so many options
When I initially wrote this post over a year ago on our own blog (blueheronhaus.com) I really was not sure that the decision we had made was the best one. Now that we are living in the house, I'm happy to report that it is performing as well as I'd hoped it would. That being said, going back and preparing this to posted on GBA, I was, to be honest, a bit nervous as to what the community might say. I'm glad to read the positive replies and comments on the post. I'd found that as soon as you venture down the road to an energy efficient home, the options for heating, insulation, and wall construction could be incredibly overwhelming. There really is no "right" answer. In our case, it was ultimately a balance of comfort, efficiency, cost, and aesthetics.
Greg - in regards to your post and specific questions. As I said, it's no doubt a difficult decision to determine what the best heating source is for a very cold climate like ours and yours. What you're planning seems like a good solution with multiple heat sources. In our situation we desired a consistent heat source, with the back-up being the wood stove for those extremely cold days, when the power goes out or simply for the enjoyment of a crackling fire. We did briefly consider the electric-resistance in-floor heating, but that was going to be more difficult for us to embed in the concrete floor which we were planning to do regardless (thermal mass and I just like concrete floors). I'd used electric in-floor heat in our previous home's bathroom and found that this worked very well with a ceramic tiled floor. I think this would work well in a bathroom, kitchen and laundry with a similarly tiled floor. Particularly if you were going to also have hardwood or carpeted floors in other rooms (which due not allow conduction of heat through those materials very well). In such a house, one might use the mini-split, baseboard heaters or electric coil for the rest of the heating needs.
On the airtightness side, we used a standard 6 mil poly vapour barrier with Tescon Profil tape around the windows and doors to assist as this is the primary area of air leakage. Of course all seams of the vapour barrier were adhered with acoustical sealant and tape as well.The 16" of dense packed cellulose in the walls provides a significant contribution to the airtightness factor. At our preliminary blower door test, we reached 0.80 ACH, which I was pretty happy with for the first test. We subsequently tightened the house up so I will be interested to see what our final blower door test reaches. Our goal is to reach the 0.60 ACH, but truthfully, I won't lose sleep if we don't make that number.
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