Final house design

Well, after twelve revisions and eight months of planning, designing, redesigning, changing, scrapping, planning, and redesigning some more we’ve finalized the house design at last. It’s funny, we had been so sure of what we wanted and didn’t want before, but gradually this all changed. I’m super happy with the design. And although it is different in some ways from our original plan (i.e. basement, open kitchen/living/dining room), it is more true to our original vision then we had ever expected: a quaint, simple, modern farmhouse. It’s crazy to think about how far our design gradually strayed from this original vision before we finally were guided back towards the root of what we wanted.

In a lot of ways designing the house has been a full circle – as we meandered away from our vision, only to come back to it. It was also an evolution. The final product was far better than what we had ever originally envisioned. So I suppose you must go through the process. You are never going to get what you want the first time through, despite how confident we felt that we knew exactly what we wanted. We didn’t. We needed to explore. We needed to think about all kinds of scenarios and possibilities before finally discovering what it is that we really want.

And so, here it is. I cannot wait to see this become a reality.

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Is Passivhaus Appropriate for a Cold Canadian Climate?

This is something I’ve been wrestling with since we decided on building a super-insulated, highly energy efficient home. And really this is something that I think a lot of builders, architects, and designers of eco- and green homes have been debating about since the Passivhaus concept came to North America in the past few years. When we initially got going on our project I was pumped on the possibility of ‘not needing an active heating system’ – as Passivhaus enthusiasts have touted their homes on. However, that really is not quite true.

Although many of these Passivhaus homes in Europe don’t necessarily use a boiler or furnace as we do in Canada, they do still technically require some way of heating. Often that is a heating coil attached to the existing ventilation unit that warms the incoming ventilated air. For our house, the possibility of using such a system simply made no sense. Passivhaus often justifies some of its standards on “user comfort.” Certainly I agree that user comfort is critical, however, in order to meet some of the rigorous standards of Passivhaus, people have tended to sacrifice comfort to meet the certification. For example, in our project, indeed, we could have used this method of heating as a secondary option, but it would not be sufficient to meet all of our heating needs despite the super-insulation. Furthermore, we need a thermal mass (concrete floor) to take advantage of the solar gains to cut down on our heat load. Those of you who have walked around on a cold concrete floor know that this is pretty uncomfortable (as a physiotherapist, I cannot count the number of people I see who complain about knee, back and foot pain due to walking on concrete floors at work). That being said, a warmed concrete floor is very pleasant, and strangely comfortable. Given that we wanted a concrete floor for both thermal mass and aesthetics, it made no sense to me not to use in-floor hydronic heat. In this case, we had to choose user comfort over Passivhaus standards.

Another major criticism of Passivhaus standards is both the annual energy consumption and annual heating/cooling consumption standards. These standards are very strict at 120 kWh/m.sq./yr and 15 kWh/m.sq./yr. I’ve previously written about these as well. But is this actually possible to attain in a very cold Canadian climate? Indeed this has been shown to be possible in a handful of projects in Canada. But not that many. Why is that? Recently we’ve run our numbers through the HOT2000 software, which is a Canadian software for energy efficient homes to calculate energy consumption. It’s not as thorough as the PHPP Passivhaus software, but it’s pretty good, and a lot cheaper to have done.

Ok so here are our numbers:

House size 1240 sq.ft (main floor) + 1240 sq.ft (basement) = 2480 sq.ft of treated floor area = 230 m.sq of total treated floor area.

Estimated Annual Space Heating Requirement: 7159 kWh / 230m.sq. = 31.13 kWh/m.sq/yr

Estimated Annual Electrical Space Heating (minus expected wood stove use): 2342 kWh / 230 m.sq. = 10.18 kwh/m.sq/yr
Estimated Annual DHW Heating: 3409 kwh
Estimated Annual Appliance: 8760 kWh
TOTAL ENERGY CONSUMPTION: 19,328 kWh / 230 m.sq = 84.04 kWh/m.sq/yr
First let me explain a couple things. One, we expect to use our wood stove a lot in the winter. I love a wood fire, there is something incredibly comforting about watching wood burn. Two, I do think that the annual appliance use is on the high side and I would also argue that our total space heating is also a bit high when comparing it to the Mill Creek NetZero house, an eco-house project using the same wall system in a similar climate. Nonetheless, let’s give these numbers some context:
Our House Projected Annual Space Heating = 31.13 kWh/m.sq/yr
Our House (minus wood stove heat) Annual Space Heating = 10.18 kWh/m.sq/yr
vs.
Passivhaus Annual Space Heating Standard = 15 kWh/m.sq/yr
Ok, so you can look at the comparison numbers I’ve provided above for Passivhaus and the average Canadian home versus our place at 31.13 (overall heat requirement) and 10.18 (electrical space heating requirement). Both of these numbers are A LOT less than the Canadian average. I’ll use the 31.13 number because it is the highest possible use we would need in an extremely cold year without using any wood heat. That is 77.3% less than the average house in Canada! Pretty awesome! And yet, it is twice as high as the Passivhaus standard!!
I’ll remind you that we are using the following: R100 ceiling, R56 above grade walls, R32 below grade walls and R32 under slab insulation. We are also having significant south glazing and minimal north glazing. We will be installing the highest efficient fiberglass windows and we expect the airtightness of the house to meet the Passivhaus standard of 0.60 air changes per hour at 50 pascals. So, WTF?
The bottom line here is that Saskatchewan is a lot friggin’ colder than Germany. The number of heating degree days in Germany in 2014 was 3100. The number of heating degree days in Saskatoon in 2014 was 6035. Well, that’s about twice as much, which would account for our need for twice the heating load – makes sense! Therefore, I have a hard time understanding how the standards of German Passivhaus can be applied to a very cold Canadian climate.
If we look at the overall Total Energy Consumption (84.04) however we are actually significantly lower than the Passivhaus standard of 120. This begs the question of, in Germany, what is accounting for the 105 kWh/m.sq/yr difference of energy if not for heating? Is their appliance and hot water use that much higher? Or is this particular standard higher to account for the larger homes and buildings that are typically built with Passivhaus? (This brings up another criticism of Passivhaus penalizing smaller homes. Check out this article for an exhaustive list of criticisms of Passivahus in North America. Passivhaus US and Canada have recognized the limitations of the European standards and are taking steps to try to modify these to be appropriate in North America. However at this time, the standards are still up for debate).
Anyways, what do these numbers really mean, except to compare apples (Germany) to oranges (Saskatchewan)? We weren’t going to be pursing Passivhaus certification anyways (at an approximate $10,000 price tag for certification, I’d rather put that money into solar panels). But I think it provides an interesting discussion. In the end we will be building a highly efficient, super-insulated house that will consume about 75-80% less energy than the average Canadian house. We truly won’t know our overall energy consumption until we actually live in the house so all of these numbers are a bit arbitrary.
Yes, you can build a “true” Passivhaus on the prairies, but you’d be looking at making huge financial investments and sacrificing comfort to meet the standards.
I’m reminded of a discussion I had with a local energy efficient home builder recently. He said: “Anyone can build an extremely energy efficient house with enough money. But to build one on a budget, now that is something impressive.”
In the end, we are building on a budget, which should come in at or below the cost of building your average stick framed house and our energy bills (100% electric) should be in the range of $100/month. I think I can live with that.

Choosing a super-insulated wall system

After deciding on the mechanical system of the house we needed to choose what type of wall system we were going to use. As I’ve learned, for an Eco-house, there’s more than one way to skin a cat! (who came up with that saying?!) Again, it was a matter of weighing the advantages of each and ensuring that our contractor felt comfortable with whatever system we decided on.

Passivhaus tends to utilize a double-wall system, although there is no set way to do this, as long as you meet the Passivhaus criteria.

Examples of Passivhaus wall systems.

This method is nothing new, there are many houses from the 1970s that utilized a system of a 2×6 wall at 16″ on centre (o/c) and offset with a 2×4 wall 16″ o/c for an interior wall. Nonetheless, biggest concerns in ensuring an exceptional envelope of a Passivhaus or any other super-insulated home is: thermal bridging and airtightness (and to a lesser degree the overall R-value).

Thermal bridging is basically an easy pathway for heat to flow out of your home. In a conventional single 2×6 wall, this happens every 16″ as the 2×6 piece of wood is connecting the inside to the outside with out a “thermal break”.  This is why a R19 insulation in a 2×6 house actually has a lot less R-value.

Airtightness is how leaky is your house? While thermal bridging can be limited by proper construction design. Airtightness can really only be ensured while on-site building the house. Airtightness is tested with a blower door test and is rated based on “air changes per hour a 50 pascals of pressure.” As previously mentioned, Passivhaus standard is 0.6 ACH. The Canadian R2000 is 1.5 ACH.

 R-value is of course also important, but less so than reducing thermal bridging and ensuring excellent airtightness. This is because R-value is a rating of the “effectiveness of insulating materials.” You could have an R50 house, but if it is leaky and has thermal bridging it will not function like a “true” R50 house.

In the last 10 years, there have been numerous high-performance, high-tech wall systems that have been developed such as Insulated Concrete Forms (ICF – concrete poured into thick pieces of foam) and Structured Insulated Panels (SIPs – OSB laminated to the inside and outside of a big piece of foam), both of which eliminate thermal bridging altogether by not utilizing timber at all.

ICF
SIPs

Passivhaus’ use a variety of options, though many that I’ve read about use some form  of double-walled systems often with SIPs on the outside and 2×4 timber framing on the inside. An 8″ thick SIPs panel is about R33 on it’s own so add that to the R11 of a 2×4 wall and you get a well-insulated house with minimal thermal bridging.

We had already decided that we would be best served, given our rural location and 55km distance from town, to pay our contractor to be at the site working – instead of driving back and forth with lumber. As such, we wanted to utilize a company that could provide either a prefabricated wall systems (which could be erected very quickly on site) or a “kit” (all of the wood cut to size to be put together like a model). Because we have a large shop on site, the materials can be all shipped at once and stored inside. Also, this significantly reduces onsite waste and chance of error.

One of the companies we looked at was Pacific Homes out of Victoria BC, who our builder has worked with on previous projects. This company produces a “Smart Wall” system – a prefabricated timber wall that eliminates thermal bridging and significantly increases R-value. A standard 2×6 wall is R19. The 2×6 Smart Wall is R31.

We compiled a list of “attributes” for each option that we felt were most important in our decision-making process:

– R-value

– Airtightness

– Ease of construction

– Construction labour time

– Material waste

– Total cost (time/money/energy)

Options for walls were as follows:

1.  Pacific Homes 2×6 Smart Wall with 4″ of rigid foam (EPS) on the outside. 

This option was appealing due to it’s low cost and simplicity. However that simplicity quickly got tossed as we are quite certain that we want to use cedar siding on the house. Trying to secure cedar siding to foam is not possible without significant strapping and labour to ensure everything is kept in place. This would work for stucco, but it would not be ideal for us. R-value of about R45. Airtightness might be less than other options given that this is really a single-wall system.

2. Pacific Homes 2×6 Smart Wall with offset 2×4 standard wall at 16″ o/c.

This is a simple option as well. The outer wall would be prefabricated  and shipped. Given the prefabrication, the house could be framed with roof, windows and doors installed in 2 weeks (same as option #1). The internal framing could be done after and standard cellulose batts used inside. The good thing about this over the first is that the plumbing and electrical would not pass through the 2×6 outer wall therefore eliminating potential air leakage. The cost of this one was quoted at about $5000 more than option #1 due to the extra 2x4s and insulation batts. R-value for this was R41.

3. 14″ thick ICF

ICF uses styrofoam forms with concrete poured into it. It’s appealing for a few reasons: no thermal bridging, super strong walls (disaster protection), has a good R-value (R48) and is naturally airtight (expect in the corners and around openings which of course need to be sealed like any other system). It’s a bit controversial though and quite a bit more costly in terms of time, money and energy. It is a labour intensive project and we simply did not think it would be worth it in our case.

4. 8″ SIPs with 2×4 standard wall at 24″ o/c

SIPs are touted as an energy conscientious option that can be installed extremely quickly. A 2000 sq.ft house can be erected in two days. SIPs uses two sheets of OSB laminated to a slab of EPS foam. It is very strong and does not require further framing. The R-value of an 8″ wall is R33 so combined with a 2×4 wall at 24″ o/c you get R44. I thought this would be a pretty excellent option. SIPs are only marginally more expensive then a standard wall system (and when you factor in the reduced labour cost, it is negligible) and are quite a bit less than ICF. Unfortunately, SIPs have been found to have some pretty serious problems with moisture build-up, airtightness problems, and early decay. None of those sounded good to me. Sorry SIPs, not for us.

5. 16″ Deep Wall System

One of the engineers on our team had worked with a group from Edmonton AB who utilized a “Deep Wall System.” I had never heard about this, but was intrigued.

Deep Wall System – Mill Creek Net Zero House, Edmonton AB

Essentially this uses a 2×4 wall 16″ o/c on the outside and 2×4 wall 24″ o/c on the inside. A 3/8″ thick piece of OSB is cut 16″ inch wide for the header and footer. The 2x4s are spaced and secured to the headers and footers with a 3/8″ OSB sheet on the outer wall. Essentially you make a box with a mesh on the inside. The 16″ cavity is filled with blown in high density cellulose. This gives an incredible R-value of R56! As if that’s not impressive enough, the material cost of building is about the same as a standard 2×6 wall (not including cost of extra labour time for framing mind you). The airtightness on the Riverdale NetZero house was 0.59 ACH and the Mill Creek NetZero house was 0.36 ACH. Amazing. As I later found out, the energy guru and one of the creators of the Saskatchewan Conservation House  (the house that inspired Wolfgang Feist and led to the German Passivhaus Institut), Rob Dumont, developed and used this exact method on his house in Saskatoon SK.  He built his house in 1992 and at the time was considered to be the most well-insulated house in the world (the airtightness was also an incredible 0.47 ACH). Why didn’t they just tell us that in the first place!? There would have been no decision-making necessary. We would have just done what he did.  We will still have a company cut all of the lumber to size and ship as a package. Although this system will take a bit more time to complete (due to framing labour) the advantages of this wall system for us far exceeded the other options.

I’m super excited for our super-insulated and locally developed wall system.

-K

Initial House Design Process

I thought we had a pretty clear idea about what we wanted in the house. We also trusted our designer to help guide us in the details. Our priority was to find an optimal balance of energy efficiency, maximizing the view, and the aesthetics of a modern design, while also respecting our budget.

Our aesthetic draws us to simplistic modern vernacular houses. These simple shapes (square or rectangle) also happen to be ideal for energy efficiency – less angles make for less escape points of energy and thermal bridging at corners. Additionally, these shapes allow for easier transfer of air and heat throughout the interior of the home. A peaked roof can be made to orient at the correct angle for solar exposure of a PV system.

That’s all well and good, but we also had this amazing view in front of us:

IMG_2293

As if fate had made it so, the views were south and east. If we’d been north facing we would be in a bit of trouble for energy efficiency – in fact, we would probably fail.

When considering energy efficient and passive solar principles, you need thermal mass. The sun hitting a thermal mass like stone, tile or concrete allows it to warm the surface and passively radiate that heat for the remainder of the day. It just so happens that we quite like concrete floors. These can be very beautiful surfaces that you can polish, grind, or stain. Naturally these all add some cost to the finishing of concrete, however the costs are significantly less than adding flooring overtop. We need the concrete for the slab anyways, so why not use it for our thermal mass and our finished floor?

The more I read about energy efficient design principles, the more and more pleased I was to find that a lot of our aesthetics were coinciding with optimal energy modelling.

Our basic house idea was for a 1700-2000 sq.ft bungalow or 1.5 storey with three bedrooms (although we are DINKs now [dual income no kids], we will likely have some rug rats (concrete rats?) running around at some point)  and two bathrooms. Also, we wanted a living room and separate media/rec room. Because we will be canning and storing a lot of our own food a large pantry was also necessary. We want to have a lot of connection to the outdoors, not just through the windows, but also a few exit points to access a deck space and various parts of the yard.

As I’ve previously written, we’d spent quite a bit of time going through Pinterest and numerous design magazines choosing our inspiration photos. As part of our early design process, we also went through and measured the room sizes we liked in our house and those of some friends and family whose room sizes we thought were nice. Still the details of how it functioned needed to be put together. This is where the designer is key.

Crystal Bueckert, our designer, is great. At our first official design meeting she basically listened to us and did the first design exactly as we’d asked. We waited with excited anticipation for the first draft to come back. About two weeks later she sent it to us. Not only did she send us a floor plans but also a 3-D model with a virtual walk-through on our laptop and iPhone. We were so excited to see what it would look like. We opened it up and… we totally hated it!

She had done exactly what we had asked but we absolutely didn’t like it. It was not what we had envisioned at all. Ok, I’m being a bit hard on it. There were a couple things we liked and there was some things that had potential, but overall it was not good. At all.

design1

The next design we revised a number of our thoughts and really tried to think about how we wanted the house to flow. We abandoned the 1/2 storey idea and went to a bungalow. We also changed the position of the living room and kitchen, which made a very significant change to the layout of the entire house… Although we wanted a relatively ‘open concept’ house (from both an energy efficiency and style point of view), we did not want it overly open and in the first design it was just too open.

The second design was a lot closer to what we were going for. Except for one big thing: we recognized that the kitchen/living room/dining room placement was actually a lot better in the first design, although the rest of the house worked WAY better than the first go around. Still we were getting closer.

design2

Sadly, the third version was a bit of a mess, we had considered moving the mechanical room to the attic to free up floor space as we really wanted to keep it under 2000 sq.ft total. That quickly came to a halt when I had a nightmare about the water heater breaking, spewing water through the ceiling and down the walls – destroying everything I cared about. I told Crystal that we had to fit the mechanical room into the main floor. We also wanted (Darcie said ‘needed’) to switch the kitchen and living room again – a massive design change again.

I’m confident the fourth design is going to be very close to the final product. The layout flows beautifully and to solve the space problems we actually went smaller. Shrinking the size from 2300 sq.ft in design #2 to 2050 sq.ft. There are a few minor changes to make, but I feel like we are about 90% completed.

design3

Now that we had the layout near completion we needed to figure out the big questions of wall systems and mechanical heating/cooling.

-K

Heating a super-insulated airtight house in a cold Northern climate

The biggest question mark for us up to this point was, “How the heck are we going to heat this place?”

First there are a couple of caveats:

  1. 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 neighbour ask us if we would consider bringing it in. But this just seemed ridiculous to me. For a cost of $20,000 you can pipe in a non-renewable resource, 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.
  2. We do have power to 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-based) or ‘natural’ gas will often select the apparent lesser of two evils and choose natural gas for heating/cooling and 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 up solar panels and generate not only our own electricity for heating, but also our own power for running everything else in the house.
  3. We are putting in a wood burning stove as a back-up 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 firewood and plant a tree in its place.

Ok, so now that we have the prerequisite information out of the way, there were still huge decisions to make. Over the past few months I’d read innumerable articles on heating options for northern climates and in particular, super-insulated houses, as well as received everyone else’s biases on the optimal heat source. I soon realized that there are dozens of different options and all of them have their own pros and cons.

Most Passive houses that I read about used a “Mini-split heat source”, the majority of which were made by a company called, “Fujitsu” out of South Korea. These are pretty cool little devices. The popular choice with most houses I read are the ductless mini-split. In a Passivhaus, the heat load is so low (usually between 10,000 to 15,000 BTUh – as an aside most standard furnaces are 60,000+ BTUh) that usually two of these little systems are sufficient for heating a 2000 sq.ft 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, preheats it and delivers it to the indoor unit for distribution. In the moderate climates of Asia, Europe and the US these are great. A major appeal for these is that in the summer they act in reverse providing air conditioning. However, in a northern climate, such as Saskatchewan, though these are likely not the best option. Previously these units would be able to preheat air as low as -5°Celsius (23°F). Fujitsu has recently come out with a new model for “Extreme Low Temp Heating”, which will heat up to -25°Celsius (-15°F) outdoor temperatures. Unfortunately, this is still 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°Celsius (-22°F) or colder. A couple years ago for the entire month of December it did not get above -25°Celsius (-13°F) for a high! There will be a few days, every year, when it is -50°Celsius (-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” mini-split to cope with that I’m afraid.

If we were to use the mini-split system then we would need to have back-up heat sources in each of the rooms of the house such as radiant wall panels or baseboard heaters to manage the cold whenever it dropped below -25°Celsius (-13°F). Although these radiant heaters are relatively cheap at less than $100 each, I must admit that I think they are kind of ugly. Well, uper 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 mini-splits 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 moulding, no baseboards. Adding BASEBOARD HEATERS just seemed like a mortal sin to our minimalist aesthetic.

Ok, breathe…

Another option that was brought forward was to use an electric reheat coil. Basically how this worked was like a typical forced air ducted system, but a little bit different. A no-brainer must-have 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, mold and air quality. We had already decided that we would use a Vanee HRV (this was developed by Dirk Vanee through the University of Saskatchewan who is credited with developing the first widely available and mass produced HRV systems) 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. How the reheat coil works is by being mounted in the mechanical room at the outlet to the fresh air thereby preheating the 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, but only because it is a super-insulated house, in a conventionally built house you would need separate ductwork. For this reason, this leads to the claim by some that in Passive Houses “conventional heating systems are rendered unnecessary throughout even the coldest of winters” (a fairly misleading statement) as it uses the pre-existing ventilation system.

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. Secondly, this is basically a forced air system. A 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. Thirdly, 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. Fourthly, we would likely still need to supplement the system… and we’re not going to talk about that again.

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 1.5” concrete slab topper on the main floor of the house for passive heating purposes as well as the required 4” 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 indeed very comfortable. 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 imbedded in the floors. No wall panels, no horrendous baseboard heaters.

Fourth, it can be zoned and controlled. Each room or area 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 master bedroom and living/dining room do not need as much floor heat because the thermal mass and solar gain will heat these areas passively, whereas the north rooms and hallways do not have solar gain and 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 super-insulated and well-built houses:

“Radiant Floor Heating: Why radiant-floor heating systems don’t make sense for new, energy-efficient houses”

“All About Radiant Floors”

“Heating a Tight, Well-insulated 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 – reduce the use of non-passive, mechanical systems. The heat load, as mentioned of 10,000-15,000 BTUh, does not require a big system like 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!

Another concern was how we would deliver this heated water through the floor. Most systems use solar thermal panels that have water pumped to the roof to be heated through copper piping, then brought down to a storage tank and boiler that heats the water to upwards of 100°Celsius. This is then pumped through the floor in a closed loop system. As we found out from our recent well water testing, we unfortunately needed to use either a whole house reverse osmosis (RO) system or have water brought in by truck and stored in a cistern. The ramifications of this being that RO water is highly corrosive to copper piping. Crap! So what were we to do?

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 US. Indeed radiant floor would be overkill for those climates, but they do not get down to extremely low temperatures like us.

It was decided the best means of 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 R2000 and extensive energy modelling experience, the mechanical contractor and my wife and I. We went through 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 of setting up this system and concerns of overheating were alleviated in this meeting. We would use our solar PV system to power a simple, small 2-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. Although the thought still seems intriguing, in another few years this may have been the best solution. Check out this article for more information). On the domestic hot water side, we selected a fairly straight-forward, 47-gallon Bradford White high efficient electric 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.

PS. This post was edited from its original version on Nov. 23/2015.

 

What is Passivhaus?

I’d never heard of “Passive House” or “Passivhaus” (as the Germans or fancy pants folks like to call it, myself included) when we started the process of starting to design our house.

I had heard of “Solar Passive House” though. As far as the history goes as I understand it, in 1973 the OAPEC (Syria, Tunisia, and Egypt) issued an oil embargo on the USA – due to some silly war on a foreign nation that Americans had gotten themselves into, again (weird). The oil embargo caused a pretty major scare to oil loving North Americans. With this sudden rise in oil prices ($12/barrel!) and potential for oil shortage, people became very worried about what a world without oil could be like… “How else can we heat our houses?!” and “How will we drive our cars?!”

Strangely enough this led to some novel and creative ideas, like “Why not insulate our houses better?” and “Maybe I could use my legs for transportation or drive with my friends and colleagues to work” and “Why don’t we use that big flaming ball of fire in the sky to magically give us free heat and energy?”

These earth shattering and brain melting ideas led to some interesting developments, one of which was the “Passive Solar House.” Some of these were better than others. But the basic concept was quite simple: Face the house to the sun, put a bunch of big windows in front of the sun, use concrete or rock on the floor or walls (thermal mass), and then insulate the walls better to retain this heat. Ta-Da! Less oil and gas to heat our crappy leaky houses!

Unfortunately for the world and future generations, only a handful of these houses were built as the oil embargo was lifted and cheap oil flowed again allowing people to forget about solar energy and other sustainable/renewable resources. People went back to the way they’d always built homes and functioned as they always had in their day to day lives. It’s sad and a bit amazing to think of where we would be as a world now if we’d have taken those sustainable ideas of renewable energy sources and continued to apply and develop them to an even greater degree. We seem to be at a similar point in history now as they were 40 years ago…

Anyways, Darcie and I actually looked at a Passive Solar House in Saskatoon when we were house hunting 5 years ago. Admittedly, most of these homes had a number of issues (although I still believe that had the oil embargo lasted longer a lot of these issues would have been easily addressed on a large scale) including: poor ventilation (they were stuffy due to lack of airflow), too hot (they felt like a greenhouse and so were often later retrofitted with air conditioning), still leaked heat and cold (not airtight), there was no passive shading outside (again overheating in summer or not adequately heating in the winter), and too humid (again poor ventilation).

What is really awesome though is that there were a very small number of houses that totally nailed it! One of those houses, considered to be the first “Passive House” was built in Regina, SK by the Saskatchewan Research Council in 1977.

saskatchewan-conservation-house

It’s pretty amazing that the first (unofficial) Passive House, using only two water heater for heat sources, was built in Saskatchewan. The Tyee has a great little write-up on it here: “Step Inside the Real House of the Future”

This house was built by some very forward-thinking people at the Saskatchewan Research Council, including Rob Dumont from Saskatoon (more on him later). They recognized some of the earlier problems with the Passive Solar House including air leakage and poor air flow/quality. They were able to develop a means of extreme airtightness and significantly reduce the leaking that happens in most houses. They also developed one of the first mechanical ventilation units that brought in fresh air from the outside, pre-heating it with stale interior air and circulating it through the home. Pretty neat!

A ton of people (upwards of 30,000) came and looked at this house in the late 1970s and 1980s. Two of those were a couple of German professor dudes named Wolfgang Feist and Bo Adamson. They studied that SK house and two others in the US that had also proven themselves to be extremely energy efficient. They returned to Germany and over the next several years studied and refined what they had seen abroad with the goal to apply it to the building of new German homes. Eventually this led them to founding the “Passivhaus Institut” and developing two basic requirements that all true Passive Houses must meet:

1. Every building must pass a blower-door test demonstrating exceptional airtightness. The Passivhaus airtightness standard (0.6 AC/H @ 50 Pascals) makes the Canadian R-2000 standard (1.5 AC/H @ 50 Pa) look lax by comparison.

2. Every building must consume no more than 15 kilowatt-hours of energy for heating/cooling per square meter of floor area and 120 kilowatt-hours per square meter for total energy consumption. While R-2000 and most other green building standards govern only energy used for heating and cooling, the Passivhaus standard applies to all energy — including lights, appliances, entertainment and hot water heating.

Ok, yea so what do those numbers mean?

The first one applies to air tightness of the building’s envelope (the walls, roof, windows, doors, and floor). Most houses are terribly leaky. I know ours is. It’s 102 years old. Even though the windows have been replaced we can feel a draft near most of them and there are cold spots throughout the house. That’s why we run our furnace, like most households, all the time. Passive House air tightness looks to eliminate air leaks and drafts to extremely minute levels. This is tested with a blower door test, which is just like it sounds: seal the doors, run a fan at the door, create negative pressure and measure air leakage. For comparison sake, most conventional houses leak at a rate of 15.0 air changes per hour (AC/H). To be certified as a Passive House, air leakage can be no more that 0.6 air changes per hour!! It doesn’t take a lot of thought to realize what a massive effect that would have on your need to heat (or cool in hot climates) your house, once it’s heated, it stays heated and you need a lot less heat to make it comfortable.

The second applies to how much total energy the house consumes. This applies to all components of a home that make it function. A high level of insulation, proper solar orientation, passive shading in the summer, solar gain in the winter, and a simple layout of the home will each have fairly significant effect on how much energy the house will require. Still, comparison helps here. Consider this:

  • The average Canadian home consume 59% of total energy in heating
    – 43,506 Btu/ft2 per year
     (137.2 kWh/m2 per year)
  • Homes built to today’s Passive House Standard, consumes 6.4% of total energy in heating
    – 4755 Btu/ft2 per year
    – (15.0 kWh/m2 per year)

Ok so basically a Passive House is 30x more airtight than a standard house and consumes 53% less energy for heat. That makes for a seriously energy efficient house. (http://design-build-energy.com/passive-house/)

Essentially this shifts the conversation of house building away from “How am I going to heat my house?” to “How am I going to keep the heat in my house?” Consider a coffee mug versus a thermos. A mug of coffee will be cool in a matter of a few minutes while a well-insulated, air-tight thermos can keep it hot for hours.

I had never thought of these common sense concepts before when considering building a house until we told our house designer and friend, Crystal Bueckert at BLDG Studio, that we wanted a “Net Zero” house. She said “Nah, you need a Passive House.”

You see, a Net Zero house can get to net zero how ever it wants as long as you balance the energy you use by what you can replace. So theoretically you could have a regular old leaky house but as long as you replace all your consumed energy with solar panels, a windmill, geothermal, etc, etc. then you could still be “net zero.”

Passive House makes reaching net zero relatively easy. You consume way less energy, so throw a few solar panels on the roof and, boom, you’re net zero. In fact, most Passive Houses with PV panels are Net Positive houses in that they feed back onto the grid as they are netting more energy then their super-insulated and airtight house needs.

Now that’s sustainable living.

-K