Musings on Passive House Standards and the Costs of New Home Construction, Part 3

Posted on by kent

If you have not yet read my posts (rants) in Part 1 and Part 2, maybe check those out first.

Have you heard of the Pareto Rule before? It’s more commonly known as the 80/20 Rule. It says that for many events, roughly 80% of the effects come from 20% of the causes.

I think that Passive House (PH) follows this rule to a T. It has certainly been our experience in building an extremely energy efficient home and following the principles of PH. I believe that 80% of the benefits of PH come from about 20% of the cost and effort (from Part 1 of these posts, I noted that our financial cost was about 8% more than a standard house construction). Whereas to get that last 20% to the hit the PH certified requirements, you’re going to have to spend 80% more… At least this was my assumption.

Still being the curious person I am and because I kept getting asked about it… I just had to know. How close does our house come to the PH standard?

The only way to find out would be to either track the house over the next year or to have someone run the house through the Passive House Planning Package software (PHPP) to predict our values.

As you may recall, we were never pursing PH certification, right from the beginning we were told the cost-effectiveness (80/20 rule) was just not there. Maybe if there was some incentive or rebate for going full-out, one could justify it. We were also told that there was no need to use the PHPP as it was too expensive. This latter statement however is simply not correct.

I decided to ask around and see who could put our house through the PHPP for us. Or at least get a price quote for it. Maybe it would be too costly and so I wouldn’t bother if it was. After a few emails, I was eventually referred to a very well-respected PH consultant out of Alberta – Stuart Fix at ReNu Building Science. I sent my email explaining that we’d already built the house and so really can’t change anything now, but due to curiosity I was wondering if he could run the house through the software. No problem he said. The price we were given was entirely reasonable and was actually less than what we had paid to run the house through the inferior HOT2000 software prior to building. Crap!

After a couple weeks we received the results, not surprisingly: we weren’t a Passive House. But the results on the various aspects of the house were very interesting and lead to some interesting points of discussion.

Based the three criteria for PH certification, recall:

  1. Space Heat Demand: max. 15 kWh/m2a  OR  Heating load max. 10 W/m2
  2. Pressurization Test Result @ 50 Pa: max. 0.6 ACH
  3. Total Primary Energy Demand: max. 120 kWh/m2a

Our results were as follows:

  1. Space Heat Demand: 37 kWh/m2a
  2. Heating load: 22 kWh/m2a
  3. Pressurization test result (assumed 0.6 ACH, prior to testing)
  4. Total Primary Energy Demand: 116 kWh/m2a

So, you can see that the only criteria we met was the Total Primary Energy Demand. The blower door test we did later came back at 0.72 ACH (we’d run the software assuming 0.6 ACH as a target). As a result of the actual pressurization value, this would correspondingly increase the other values, but, for argument’s sake, let’s simply say that the Total Primary Energy Demand we either met, or were very close to meeting, while for the Heat Demand and Heat Load, we were WAY above the German PH maximum values.

I won’t reiterate why this makes sense given the climatic and heating requirement differences of the Canadian prairies versus Germany (see Part 2). But I had to ask the PH consultant:

“If we were still in the planning stages of the house, what would be your recommendations to try and reduce these two values (Space heating demand and heating load)? Not that we would change anything at this point, but I’d be curious as to how we would have gotten those values lower – and if it would have been at all possible with our type of house and in our climate to feasibly meet the PH requirements as stated?”

​The ways to reduce the heating load & demand are as follows:
  • More insulation (you already have great R-values)
  • Lower airtightness (dropping from 0.6 to 0.3 has quite an impact, but you’re already doing tremendously well)
  • Add more south glazing, reduce all other glazing. (You already have a great balance of glazing)
  • Build a larger home (!?!?… small homes are the hardest to make meet an intensity based target, as they have the largest surface area to volume ratio. Meaning that a larger building squeezes more floor area into slightly more exterior envelope area, reducing heat loss per unit of floor area. The Germans do this to motivate one to build multi-family dwellings… but the result in North America has been a lot of larger single family homes getting certified).
​Your home is a great example of why you don’t see certified Passive House buildings taking off in Canada. It’s damn near impossible to design a compliant home, without either blowing the bank or ending up with a solar oven. I’ve designed many compliant buildings, and 99% of them end up backing off on insulation and glazing to be around where your home is. You’ll note that local Net Zero Energy homes have similar envelope performance to your home; it’s most cost effective from that baseline to invest in ​solar PV generation than to add more insulation.​

Under the section of the report on Energy Balance Heating, I asked, “I was surprised by the amount of heat loss through the walls as well as the windows – is that due to the size/number of south windows? Or does that relate to the number of windows on the east/west and north sides more so? How could we have changed that to reduce the heat loss?”

Ideally, if the insulation in all areas of the building cost the same, you’d want to balance the R-values so that the heat loss intensity rate is the same through all envelope elements. Your exterior above grade wall has the highest relative rate of heat loss, so that’d be the place to add more insulation first if you want to improve performance. If you want to optimize R-value ratios this way, it’s smartest to add in the cost/ft2 of each insulation type, then you can maximise your return on investment. For example, adding 1″ of cellulose in the attic is much cheaper than an inch of foam outside of a wall.
The glazing of course has the highest rate of heat loss, but that’s just because you max out at around R10, where your opaque assemblies are R50+.
Your North, East, and West windows are NET losers of heat, while the South windows offer a net gain. This is as expected, and is really the basis of Passive Solar design, that a South window can actually HEAT a building throughout the heating season, with the right recipe. If you wanted to optimize the glazing further, you can add more South glazing while removing glazing on the other elevations (North being the biggest drag on efficiency), which will continually reduce the annual heating demand (how much energy is consumed to heat). This is a Red Flag area though, following this path of more South glazing will eventually cause overheating throughout the year. Prediction of overheating / discomfort is an area where the PHPP is very poor, and I’ve been burned in the past on some projects where we pushed the Passive solar too far in an attempt to reach certification. I now use IES<VE> as a energy modelling tool because of its ability to accurately predict overheating.
“Did you have any thoughts or considerations you would have given us had we run these numbers off the bat with the house planning? “
I’d honestly say you’ve done a great job on your home. It’s pretty much impossible to meet the PHI Passive House criteria for a small single family home in Saskatchewan, without significant and typically unjustifiably cost. The PHIUS criteria is based on a more climate-specific analysis, which attempts to stop investment in conservation at the point a little bit beyond where renewable generation is more feasible. Meaning it’s more realistic to meet the PHIUS+ targets, though we’re not seeing much uptake in the Prairies.​
All of this was very interesting and at the same time reassuring to me. Like many others, I had put a lot of credence on the PH standards as the be all and end all (even still despite reading and appreciating the issues I’ve previously discussed). It was good to hear that the assumptions we’d made were in the end in line with the reality of trying to build a PH in Saskatchewan.
Even still there was one last thing that I just had to know… it kept coming up again and again. It was one of those pesky assumptions we kept getting asked about. And one of my recently reposted blogs on Green Building Advisor brought it back to my mind again… German windows.
It is regarded that the German (or Polish and Lithuanian) Passive House certified windows are the creme de la creme of windows. They are attractive, heavy, thick (6″ wide!), and expensive. But if you want to reach Passive House standards, you gotta have ’em! (Or at least that’s what they say).
I felt a little bit guilty asking for quotes on windows that we were never going to buy, but my curiosity just couldn’t be helped. I wanted to know how expensive PH-certified windows would have been for our place. We’d heard outrageous prices of up to $80,000 for some homes.
We tendered a couple of quotes and received a reply from Optiwin of Lithuania. The salesperson was exceptionally thorough and I was really impressed with his communication (which made me feel more guilty). After a couple of weeks I received the pricing back. I was actually surprised that the cost of the PH windows was only $17,000 CDN more than the windows we purchased from Duxton Windows. Although they would have been certainly way outside our budget anyway – they weren’t 400% more than the price we paid by any means (just a measly 75% more). Nonetheless, I really had to pause again and wonder, why? What would make these windows $17,000 better than the fibreglass, triple pane windows we got? The U-factors and solar heat gain coefficients were not that big a difference. Maybe the the locking mechanisms of the windows could get you a bit lower on your airtightness – but $17,000? How long would it take you to save on heating bills to justify that “investment”?
All this being said, I’m happy to have answered my lingering questions and to confirm some of my assumptions. The bottomline, of course, though is that you want to be able to sit back and be happy with what is around you. To know that you did the best you could in building a sustainable home for the future.
I can’t complain.
IMG_3500

Musings on Passive House Standards and the Costs of New Home Construction, Part 2

Posted on by kent

If you have not read Part 1 yet, please go back and read it first. 

In mid-November of 2015, just prior to us moving into the house, we were asked to be apart of the Passive House Days tour (a world-wide weekend of awareness of Passive House and energy efficient building). Well, not “officially” – we were asked to be apart of the tour by the event organizer in Saskatchewan who is the Passive House (PH) consultant on what should become the first certified PH in the Saskatchewan. Even though we did not build a PH, we did follow their standards as closely as I could justify, but from the beginning we were not pursuing certification.

Although all of the visitors on the PH Days Tour were very interested in our house, our process, and why we did the things we did, one question we got a lot was, “If you were following the PH standards why not go all the way for certification?”

First, let’s back-up a little bit. Indeed the principles of a PH are second to none. From Passipedia: “Passivhaus is a building standard that is truly energy efficient, comfortable and affordable at the same time.” So simple. Brilliant even. I wanted to build a PH. Who wouldn’t?

Strangely, if you visit Canadian Passive House Institute (CanPHI) website there are total of 5 projects that have received Canadian PH certification. If you look up the PH Project Database there are a grand total of 23 houses in all of Canada that have received certification.

Why the discrepancy you may ask? Why so few certified projects?

This is a bit complicated and took me awhile to figure out. But here are the basics as I understand it: the Passivhaus standards were developed in Germany for German buildings in the German climate (obviously). However, when other builders in other countries tried to build a “Passivhaus” in say the USA, England, or Canada, they realized something profound: Hey… wait a second… I don’t live in Germany!

Maybe trying to build to German PH certified standards in Minnesota or Saskatchewan is going to be really difficult? Maybe impossible? Or maybe possible but really expensive? Or maybe possible but a really uncomfortable building to actually live in?

Still PH institute satellites started to spring up in most countries around the world. Slowly, Passive Houses, built to the German requirements, started to be built in other countries with the first certified Canadian building being built in 2009. The uptake, however, was certainly not rapid nor widespread. Why? Was it not as the PH Institute of Germany said that these buildings are “truly energy efficient, comfortable and affordable”? Or is it just that we are too cheap and/or lazy and/or complacent to meet those strict German requirements elsewhere?

It seems like this is something that these PH satellites were struggling with as discussed here, here and here.

A few years ago though, some people started to say, this is silly – why are we following German standards and requirements for our buildings when we don’t actually live in Germany?

The German PH standards are as follows:

  1. Space Heat Demand: max. 15 kWh/m2a  OR  Heating load max. 10 W/m2
  2. Pressurization Test Result @ 50 Pa: max. 0.6 ACH
  3. Total Primary Energy Demand: max. 120 kWh/m2a

Simple enough right? Hit these numbers using the PH planning software and your building can be certified as a PH. Where’s the problem?

The Pressurization Test for 0.6 ACH is strict, but not impossible. There had been many houses built to this level of airtightness before PH came around. Rob Dumont’s own home in Saskatoon in 1992 tested at an awe-inspiring 0.47 ACH.

Jumping to the third requirement, the Total Primary Energy Demand of 120 kWh/m2a ensures essentially that you are not wasting energy or are at least using it wisely. It forces you to use energy efficient lighting, appliances and mechanical systems. I don’t think anyone can argue with that as being important to green building.

The real problem though, in my opinion, is the Space Heating Demand of 15 kWh/m2a or heat load of 10 W/m2. These numbers dictate the maximum space heating allowed for each square meter of a building. Remember – this is based on a German climate.

In Germany the number of heating degree days (HDD) is around 3100 compared to over 10,000 HDD in Saskatoon. So that means there is over three times as much heating requirement in Saskatoon as compared to Germany. Besides that, who really cares what your heating demand is? With the maximum energy demand of 120 kWh/m2a already stated, what difference does it make whether you use 50% of that to heat your house or 10% in terms of your overall efficiency? This is my real beef with PH and the one that most others working towards PH in countries that have climates other than a German one tend to struggle with too.

Recently the PH Institute in the USA (PHIUS) split off (or was banished – depending on what you read) from it’s affiliation with the German PHI. This allowed them to develop their own standards and specific requirements for climate zones in the USA (Minneapolis also has different heating needs compared to Miami) and also to use North American calculation values instead of European. As a result it is now easier – ok, let’s say, attainable – to hit the PH targets for your Minneapolis house using a Minneapolis climate to calculate your requirements. Now that makes sense to me.

Sadly, the Canadian PH Institute has been resistant to following their American counterparts and has continued to align itself with the German requirements. Thus making it darn near practically impossible to meet the PH standard and become certified by the Canadian PH Institute.

There is a small loop-hole of sorts though, a Canadian house can pursue certification via the PHIUS, which is somewhat closer to our climate in the northern States. Although the conversion is not exact, the Space Heating Demand requirement for the northern USA is about 30 kWh/m2a (or double that of the German standard maximum). That’s better, but still the maximum heating degree days in Saskatoon are more than any other place in continental USA. Nonetheless, there have been a few of PHs in Canada that have used the US system to become certified (ok, like maybe 10 or 12).

I told you this was complicated…

Anyway, let’s try to bring this full circle, back to my original question of why don’t we just build all new houses in Canada to the PH standard?

I hope that I have presented the argument that it may not be realistic to build a certified PH in Canada and follow the original edicts of the German Passivhaus Institute of “energy efficient, comfortable and affordable.”

From Part 1 of this post, you may be able to see that there is a HUGE chasm between how most new homes in Canada are currently built as a result of our pathetic building code allowing inefficient homes to perpetuate, and the extremely difficult PH standards currently set in Canada.

Unfortunately, I think the CanPHI has done itself a disservice in not distancing itself from the German PH Institute. By not developing it’s own Canadian climate specific standards for the unique climate zones of our country, which maybe (just maybe) one day could be adopted on a large nation-wide scale.

Until such a time that the CanPHI recognizes this and modifies their requirements appropriately and regionally, I doubt that PH will ever gain much more than a very small handful of faithful followers willing to spend, at all costs, to meet an arbitrary set of values developed on the other side of the world.

That being said, I do KNOW that you CAN in fact build a house in Canada that IS energy efficient, comfortable and affordable.

But it isn’t a Passive House. 

Because that’s what we’ve done.

house-snow

Musings on Passive House Standards and the Costs of New Home Construction, Part 1

Posted on by kent

A friend of mine sent me this article for Tree Hugger yesterday about an Irish county that made the Passive House standard for all new home construction. This is a pretty big deal. The question then came up – why doesn’t Canada (or the USA) adopt such strict and stringent standards to their new home construction? Certainly the Paris Climate Conference of 2015 has finally made it official what everyone and their dog already knew: the world is overheating and we need to do something about it before we all die. Building better homes could make a massive difference in our world’s energy use. It is well-known that a certified Passive House uses 80-90% less energy than a standard house.

The problem, as usual though, in making such rigorous standards mandatory is a combination of bureaucracy, status quo, and resistance to change. In this post and my next, I will make the argument that I believe there is a skewed perspective on both sides of this battle in Canada.

Did you know that the minimum standard for wall construction in Saskatchewan (a province that has frigid winters of -40° temperatures for long stretches and over 10,000 heating degree days per year) is a 2×6 wall with batt insulation? The effective R-value of this wall is only R17.5 due to thermal bridging (as the wood studs bridge between the inside and outside of the wall). This standard must be out of date, you say? In fact, this was recently upgraded to this absurdly pathetic level in 2012 (it was only a 2×4 wall before that). Shameful.

As if this wasn’t bad enough, most homes in Saskatchewan feature R12 in basement walls and only R40 in the attic. There is no requirement for insulation under the slab of the house. Also, the building code requires only double-pane windows – such insufficient windows account for a massive amount of heat loss of up to 50% (these are usually vinyl framed windows, though sometimes wood or aluminum). And placement of these crappy windows can lead to further issues with heat loss due to inadequate southern exposure and large windows on the north side of house. Furthermore, air leakage rates in most new homes is about 2.0 ACH@50pascals (which is actually one of the lowest values tested in Canada). (Source: Energy Standards by Ken Cooper)

I assume that you can get the picture that our homes are generally very inefficient (don’t think that this is specific to Saskatchewan – this is relatively consistent across North America).

Although we did not build a Passive House, we followed the principles of this as closely as we could financially justify (which is the rub, more on this in my next post). For a quick comparison, our house has R56 walls, R80 attic, R32 basement walls and under-slab. Our latest air tightness test was 0.72 ACH@50pascals (and with some extra tightening we’re hoping to get this to 0.65 or less at the next test). We used triple-pane fibreglass windows. The design of the house maximized heat gain through the south windows and minimized heat loss through the windows on the east, west and north sides. Passive shading with our roof overhangs prevents overheating in the summer. The positioning of the house is directly south (a luxury we have living on an acreage). We also installed PV panels to offset our meagre energy use, which are becoming more and more affordable.

Now, a lot of people wonder and ask (I know I did prior to building), that it must cost substantially more money to build a house to this level of efficiency?

The simple truth is that it does not have to.

The general consensus is that a new custom home in Canada, excluding the cost of purchasing land, is between $200 and $300 per square foot to build (a contractor spec “cookie cutter” home built to the minimum standard with minimal features and cheap finishing can be $175/sq.ft or less). Indeed this is large range – for a 1500sq.ft home you could either spend $300,000 or $450,000. But for argument’s sake, let’s say $250/sq.ft is a realistic cost of a new custom home (we will also assume that most people would not build to the bare minimum construction standard of a spec house and see the benefit of adding triple pane windows and a 2″ layer of EPS foam on the outside of their 2×6 wall).

OK so where are the extra costs?

I would say that the design planning and orientation of the house will be the single biggest factor in determining your initial and long-term costs in a high performance, energy efficient house. It does not cost anymore to build a house with your windows facing north instead of facing south. Positioning the long side of your house to east does not cost anymore than facing it south. Designing correct overhangs for shading does not cost anymore than designing insufficient overhangs. Designing outcroppings, bay windows, and cantilevers does not cost anymore to design than a rectangle or a square-shaped building. Placing operable windows appropriately for cross-ventilation does not cost anything extra either. But all of these decisions and factors can have huge ramifications on the cost of construction and/or long-term costs of operation. We had several team meetings during our design process (including a Passive House certified designer, contractor, and LEED engineers) to decide on which systems would be best suited to be optimally energy efficient, be comfortable to live in, and also to make sure everyone, including sub-contractors were on the same page. This extra consulting time accounted for 2.5% of our overall cost.

In terms of actual construction costs, we built a double 2×4 stud wall that is 16″ wide. The cost of materials for this wall system versus the cost of 2x6s and the 2″ of EPS foam is almost negligible. Framing labour costs were slightly more though as each exterior wall was built twice (accounting for an additional 2% of the overall budget). Remember though our design is simple, a rectangle, meaning four walls – no bays or outcroppings. We also invested 20% more in purchasing fibreglass framed triple-pane windows versus the usual vinyl or wood triple-pane windows (accounting for an additional 1.75% of the overall budget). Insulation costs slightly more but pays for itself in short order when compared to long-term operation costs (the upfront cost is an additional 2% of the overall budget). Airtightness of the house did not cost us anymore than the standard vapour barrier (although it does require some attention to detail by the tradespeople) with the exception that we needed to install a heat-recovery ventilator which cost $1200 (0.3% of the budget).

But there are also some possible cost savings to consider. One can get away with a smaller mechanical heating system due to the lower heat load required in a super-insulated and airtight house. For us, our mechanical system cost about the same as a standard house due to us deciding to install in-floor heating and a wood burning stove. Although you certainly could get away with baseboard heaters or a very small forced air furnace combined with a heat coil on your HRV if you so chose (for us we wanted the in-floor heat and a wood stove – you can read about our reasons for this here and here). Most new houses also have air conditioners installed. We do not (cross-ventilation, insulation and proper shading is all that is needed).

The bottom line is that it cost us about 8% more to build a house that is in the range of 75-80% more efficient then a standard new custom home.

After these extra costs are accounted for the rest of construction costs are basically the same as any other house – how much do you want to spend to finish the house is based on your taste and how much you want to invest in your bathroom fixtures, lighting, hardwood flooring, custom cabinets (vs. Ikea), appliances and so on. Also, how much sweat equity do you want to do yourself? All of this will have a big impact on your end costs (consider, painting our house took 5 full days, but saved us about $6,000+. Installing the tile in the bathrooms and kitchen ourselves took 10+ full days, but saved us another $8,000).

Ok, so you’re probably thinking, how much did this damn house actually cost you? Tell me already! Although I haven’t done our final-final tally yet, it is in the range of $280/sq.ft. But this also includes the cost of our 6.2 kW solar PV system, our septic system, and the cost of trades to travel the 30 minutes to our house each day. Removing these factors, to build the same house in an urban area, you could easily do it for $250/sq.ft.

Say… that’s pretty much the same as what we said a typical new house would cost, right?

So why the heck isn’t everyone doing this??

Well, it goes back to the fact that there is an unfounded assumption that building an energy efficient house costs a lot more (I think we’ve shown that it simply does not have to). It also does not help that energy costs from non-renewables such as coal-fired electricity and natural gas are very cheap still (even so, those extra 8% in building costs for us should be paid back in less than 12 years in monthly energy bill savings). And the public outcry for action is not yet greater than the apathy of maintaining the status quo on the part of our government, the building industry, and those contractors who have been making a tidy profit on their suburban sprawl spec houses.

Part two to come…

IMG_3359

Observations, expectations, and regrets

Posted on by kent

As I’ve written about building our house over the past 18 months or so, I’ve commented several times that the decisions we were making in energy performance and efficiency of the house were all theoretical. Certainly, we based our decisions and assumptions on solid foundations of research, well-established protocols, software design and modelling, and the recommendations of others who have built high performance buildings or through websites and blogs of others. But STILL. I couldn’t be sure how the house would actually function. How efficient would it be? Would we overheat? How much solar power would be generate? What are our power bills going to be? How comfortable will we be? Oh and of course, do we have any regrets? These were all questions on move-in day that we had yet to answer.

Here are some observations from the first three months of living in the house.

We have had an unseasonably mild winter this year including several days of above freezing temperatures in January and February, which generally are our coldest months of the years. In fact, the past 5 days have been between +1°C (34°F) and +6°C (43°F). Normally the ice from the river is not breaking up until mid- to late March, but just yesterday it’s already opened up (#globalwarming).

river
View from the Great Room

But even so, we have had a few of our more typical extremely cold days too (we couldn’t get off this easy of course). In December we had a couple days of -40°C (-40°F) or colder. One of these days was a bright and sunny Saturday, the news here reported that it was the highest day of power usage across the province for the year. Our dogs were lying in the sun panting and the temperature on the thermostat read 24°C (76°F) – without the boiler running – purely from passive solar heating. I had to laugh. We even had to crack a window for awhile so we didn’t overheat.

warmday

Even though that day was great to see how well things performed under extreme conditions (very cold day + lots of sun = no active heating required. Awesome) I was a bit worried that we might overheat on milder winter days with lots of sun. But, for whatever reason, this really hasn’t been the case. Within a few days of that extreme cold snap, we were back above freezing temperatures with lots of sunlight. I think a couple days it did creep up to +26°C (+78°F) on the thermostat due to passive heating, but with our well-planned operable window placements, we could simply open a window or two and cool things down if needed. It seems bizarre to me that I’d need to open a window in the middle of winter, but it really does not bother me to do it. But it also makes me very happy (and relieved) that we really thought out well how to get good cross-breeze ventilation throughout the house (although we thought this would be for summer passive cooling not the winter too!). If we didn’t have this I might be cursing myself due to overheating issues.

All this being said, of course, on cold and cloudy days, the boiler and in-floor heat runs. We have it set to keep the indoor temperature at 20°C (70°F). We played around a bit with what setting to keep it at – going as high as 72°F (comfortable all the time, but easier to overheat with passive heating, also running the wood stove would make it too warm) and as low as 68°F (too cold in the morning, even with a sweater on, and needed to be running the wood stove morning and evening). We both wear a sweater in the house in the morning – cheaper to put a sweater on then to pay for more power. If it is really cold out then I light a fire in the wood burning stove, which is a nice luxury to have. When we tried setting a lower temperature in the house, I was needing to light a fire every morning, which was a hassle and not something I was overly motivated to do every day.

I’ve started tracking our solar generation through our 6.2 KW ground mount PV system with the plan to monitor this for the year. This time of year makes for the least amount of solar generation due to the short days, more cloud cover, lower height of the sun in the sky, and SNOW. I’d not really considered it before but snow and ice covering the PV panels is crazy frustrating. I guess I assumed the snow would just fall of it. Not so. The first couple of times this happened I shouted out in horror – we had a bright sunny day, but due to a snowfall in the nighttime our panels were 100% covered! I grabbed a ladder climbing up to clean the panels with a broom – an arduous task with the wind blowing and -20°C (-4°F) temperatures. There must be a solution to this I thought, but after reading several websites, it seems like the only solution is a long broom handle or to wait for the sun to melt it off. This was so aggravating – seeing our energy generation oppurtunities being squandered. Aside from a 16′ long broom handle, I’ve not yet found a good solution to this problem (and perhaps there is no solution).

I’ve also started tracking our energy use, but this has been more difficult as we have an outdoor chicken coop with a heat lamp and a water heater that is on 24/7. These suck energy like crazy. I’m sure these three chickens are costing us a fortune right now (they better start laying golden eggs) – in fact, I think heating their little 24sq.ft coop is more expensive then heating our 1240sq.ft. house. So for this year we will see what the total energy use. But for next year, we have a second transformer located next at our shop (and not connected to the PV panels), so I will try to run the chicken coop power from there, which will give us a more accurate reading of the house’s energy use for 2017. (I also need to build a passive house chicken coop now).

I guess the last thing that everyone seems to ask – which is interesting as it is one of the first things they ask after, “So you’re all settled into the house?” … “Any regrets?” or “Anything you would change?” To be perfectly honest, my answer is, “No. Nothing.”

We really love the house. We love the design. We love the style. We love it’s performance. We love the comfort.

We spent a lot of time planning, designing, and researching the house. We did not compromise and we followed the adage to: “Do it right the first time.”

I have no regrets.

Is Passivhaus Appropriate for a Cold Canadian Climate?

Posted on by kent

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

Posted on by kent

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

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

Posted on by kent

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.