How Were Our Energy Predictions? An Analysis of the First Year Energy Use: Solar and Energy Performance

Posted on by kent

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We had spent a lot of time planning and designing a house that would be energy efficient, aesthetically pleasing, and cost effective. This is a fine balance to try to find. However, it really is a big guessing game until you actually live in the space and track it’s performance. You can run all of the computer programs you want, but you really don’t know how things will be until you’re in and living your normal life.

We had installed PV solar panels on the house to combat some of our energy use with the hope that someday we could work towards a Net Zero home, but this too, seemed to be a big guess as to how well it would perform.

In the planning and designing stages of the house we ran a couple different energy models on the house. The first is called the “HOT2000” program. “HOT2000 is an energy simulation and design tool for low-rise residential buildings.  This software is widely used across Canada to support program, policy and regulatory development and implementation.  HOT2000 is developed and managed by the Office of Energy Efficiency at Natural Resources Canada” (NRCAN). It was originally designed for use with the R2000 energy efficiency program, which was an early promoter of green home building in Canada.

We later used the Passive House Planning Package (PHPP), which is now the widely used software program for building highly efficient homes worldwide.

My intent with this article is to report the varying predictions of the these two programs, as well as our predicted solar generation, and also to show our actual energy use for the year of 2016 – our first full year in the new house. I’ll also report some considerations and possible options for the future.

1: PRE-BUILD ENERGY MODELLING

I had been very curious about this when we were in the early stages of planning the house. Most of what I read was the predictions of various homes, but I’d only come across one house that actually tracked and reported its energy use – that being the Mill Creek Net Zero House in Edmonton, AB, Canada. Which, although using exceptionally little energy, did not meet it’s net zero target. That being said, it was very close.

I fully did not expect our home to be anywhere close to net zero, but we hoped that over the next number of years we could gradually build our solar panel array (as costs come down) to eventually reach our goal.

OK, let’s get to the numbers:

HOT2000 Predictions:

Annual Space Heating Energy Consumption: 7159 kWh

Annual Domestic Hot Water (DHW) Energy Consumption: 3409 kWh

Annual Appliance Energy Consumption: 8760 kWh

TOTAL = 19,328 kWh/year

PHPP Predictions:

Annual Space Heating Energy Consumption: 7584 kWh

Annual DHW Energy Consumption: 3974 kWh

Annual Appliance Energy Consumption: 11,310 kWh

TOTAL = 22,868 kWh/year

PV Array Predictions (6.2 KW)

PHPP Estimation: 7321 kWh/year

Solar Installer’s Estimation: 9300 kWh/year

So obviously there are discrepancies between the HOT2000 and the PHPP. Although their prediction of Heating and DHW are quite close, surprisingly the Appliance use was significantly different. Also, surprising was the discrepancy in the solar predictions – I was a bit disconcerted by the drastic difference of 2000 kWh/year!!

For comparison’s sake, according to Stats Canada website’s most recent 2011 home energy use data, a Saskatchewan home consumes an average of 30,555 kWh/year (110 GJ), of which electricity for appliance use is 8889 kWh/year (32 GJ).

Drum roll please.

… Actually first, some clarifications. All I have is our actual overall energy use. I cannot separate out Heating vs. DHW vs. Appliances unfortunately, although this would be interesting. The following information is taken from the solar panel’s generation and the Electrical meter. I tracked each month and have recorded it below.

OK, now the drum roll.

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2. ACTUAL ENERGY CONSUMPTION AND PV GENERATION:

January: Solar generated = 315 kWh vs. Energy Use = 3323 kWh

  • Yikes! I was a pretty worried when I saw this. That being said, January was very cold and has very short, dark days (-20° to -30°Celsius most days. We kept the house around 71°F).

February: Solar generated = 553 kWh vs. Energy Use = 2706 kWh

  • February is always a cold month. Although you can see the solar was getting a bit more sunlight already as the days lengthened.

March: Solar generated = 603 kWh vs. Energy Use = 1716 kWh

  • This was getting a bit better still. I lowered the house temperature to 69°F. It was getting warmer outside and more solar gain.

April: Solar generated = 979 kWh vs. Energy Use = 1385 kWh

  • April was warm and sunny. Nice spring weather. Started to not need the in-floor heat on at all during the day, but still ran it during the night.

May: Solar generated = 960 kWh vs. Energy Use = 1029 kWh

  • Almost net zero for the month. It was a very nice month. We were running our river pump frequently to water new grass, which I think increased energy use quite a lot.

June: Solar generated = 1434 kWh vs. Energy Use = 989 kWh

  • Net Positive in a big way. Beautiful month. Obviously the longest days of the year.

July: Solar generated = 956 kWh vs. Energy Use = 511 kWh

  • The first two weeks of July were cloudy and rainy which is unusual for July.

August: Solar generated = 950 kWh vs. Energy Use = 645 kWh

  • This month was very rainy as well, which again, isnot normal. Usually August is very hot.

September: Solar generated = 778 kWh vs. Energy Use = 611 kWh

  • Cool and cloudy. I replanted grass seed and was running the river pump a lot again.

October: Solar generated = 315 kWh vs. Energy Use = 1478 kWh

  • October sucked!! 315 kWh is the same as January! It snowed on October 4th. We had to turn the heat back on. There were only 2-3 sunny days all month.

November: Solar generated = 390 kWh vs. Energy Use = 1750 kWh

  • Cloudy month, but had some mild days mid-month with above freezing temperatures. Still, we generated more solar in November then October, which should not happen.

December: Solar generated = 229 kWh vs. Energy Use = 2857 kWh

  • Shortest days of the year and extremely cold (-40°F). What do you expect?

ACTUAL TOTALS:

Actual Solar PV Generated = 8189 kWh

Actual Household Energy Consumed = 19,000 kWh

Actual Total Energy Used (consumption – PV) = 10,811 kWh

3. DISCUSSION

I’m extremely pleased with these numbers! I’ve been waiting for two and a half years to know what our actual energy use would be.

We actually used less overall energy then was predicted by both the HOT2000 (19,328 kWh/year, although it was close) and a LOT less then PHPP (22,868 kWh/year), which is surprising that it was so off… It makes me wonder how close we would be to meeting the Passive House standard given the actual energy use is 3868 kWh less then it predicted… Hmm. Maybe we should have tried to hit that airtightness target of 0.6 ACH after all. Oh well.

Nonetheless, the overall energy use of 19,000 kWh is very good (and such a nice round number too!). We did not do anything different in terms of our behaviour except to just be smart and not be wasteful. I still baked bread every weekend and we used our larger appliances just like we normally would. We have two refrigerators and two deep freezers in the house. All the lights are LEDs. We try to hang our clothes to dry. We used our wood stove occasionally, maybe 2-3 times per week, but mostly just for ambiance and occasionally on the extremely cold days. That being said, based on the predicted numbers, the heating energy likely accounts for about 50% of our overall energy use. Makes me wonder too how much better we could do if we burned wood a bit more often?

As for the actual solar PV generation (8189 kWh), it pretty well split the difference between the installer’s predicted 9300 kWh/year and the PHPP prediction of 7321 kWh/year. I think this past year was on the cloudier side for sure. We had a lot of rain in the Spring and even more in the Fall, which is very unusual. Followed by an extremely early snowfall which seriously cut into our PV generation (see October – brutal). It probably would be closer to the installer’s prediction on a typical year (will have to see what 2017 brings).

Still based on the actual numbers, our solar panels did cover nearly 45% of our overall energy use for 2016. We would however need to double our solar panels (add another 6.2 KW array) to meet Net Zero with consistency year to year. Who knows, maybe in the coming years the costs will drop more and perhaps government incentives will increase. One can hope.

Comparing our house to the average Saskatchewan home consumption of 30,555 kWh, we did very well. Using 37% less energy then the average home. And when you take into account the solar energy generated that drops us further to using 65% less energy then the average house! Sweetness.

Considering that we are completely on electric energy, it makes sense to make the house as energy efficient as possible. The cost of electricity for us is $0.12224/kWh (while cost for natural gas power is about $0.04/kWh equivalent), which works out to an electricity bill of $1321.54/year (10,811 kWh x 0.12224). We do however have to pay a basic service fee of $32.61/month (even when we are net positive in a month) which sucks and then 5% tax. That brings our absolute costs for the year to $1798.50/year or $149.88/month, which is about half the cost of our previous homes power and electricity bill. I’m ok with that.

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This post was updated on March 4, 2017. 

Once you go black…

Posted on by kent

We’d really hummed and hawed about what to do about the basement parging for most the winder and early spring. Although our plan had been to do the house all black initially.

 

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But last year we’d hesitated. And I’m not entirely sure why. We couldn’t run the wood siding all the way to the ground, like the rendering shows, because of the 8” of foam on the exterior basement walls without some seriously extensive strapping. Alas we had the stucco guys parge the basement foundation and then leave it while we contemplated our options: leave it or go all black.

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While taking photos for the post about the concrete retaining wall, Darcie, my wife, said, “The house doesn’t look right. It looks like it’s floating. It’s weird.” She proceeded to spend the next several days playing with Photoshop, filling the gray parging with black and analyzing it from multiple angles. After a week of scrutinizing the Photoshopped images, she said, “Look. We should do this.” Pointing to an all black house.

If there’s one thing I’ve learned is that once my wife has made up her mind, it’s best not to disagree. It is only futile afterall. “Yes honey,” I replied (these two words are the most important for a husband to know, by the way).

So I called the stucco guys and asked them to come back. It ended up taking a number of weeks for them to finally show up (typical). But only a couple hours for them to transform the house.

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I gotta say, I don’t know why I’d hesitated, because once your go black… well, you know the rest.

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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.
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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.

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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…

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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).

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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.

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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.

Airtightness: Blower Door Testing

Posted on by kent

Excellent levels of airtightness are equally, if not more, important to the level of insulation you decide to put into your house. These really are (insulation and airtightness) the two pillars of an passive house and pretty well any other Eco-house building.

For our house, we’d gone with high levels of insulation in the range of 3x the typical amount for standard construction: R32 under-slab and basement walls, R56 walls, and R80 attic. However in deciding our insulation levels and our targeting goals for airtightness, we did try to strike a balance between cost-benefit and recognize the point of diminishing returns.

I have written about our insulation choices previously here and here, so I will not go into that as much, but in terms of airtightness there are some basics that are worth discussing. The fact is: air leaking into and out of a building is not efficient no matter how much insulation you have in the walls. Although insulation decisions, thermal bridging reduction, and solar gain can be designed into the house, airtightness can really only be ensured while actually constructing the building. Airtightness is tested with a blower door test and is rated based on “air changes per hour a 50 pascals of pressure.” Typical construction in Canada reaches about 3 ACH. The Canadian R2000, our high-efficient energy standard, is 1.5 ACH. While the Passive House standard is a whopping 0.6 ACH.

Although I was hoping we could target the extremely difficult goal of 0.6 ACH as per Passive House standard, the question was – how far ($$$) are you willing to go to reach this? As with insulation levels, there is a point of diminishing returns. Will 0.8 ACH versus 0.6 ACH be anymore noticeable in terms of user comfort? And over the lifespan of the building would you ever balance out these costs?

We decided to set an ambitious, but realistic goal, of 0.8 ACH.

The reason for this was four-fold:

  • 1. Our house is not big. It is a rectangular bungalow at 1240 sq.ft. The blower door test is an test of absolute air leakage from the building – not a relative test. By that I mean, that a large house can more easily meet a lower ACH level then a smaller house due to the greater volume of the house overall.
  • 2. We were not prepared to spend the greater amount of money on air sealing tapes, interior sheathing, and the labour to do this. A standard house is sealed with a 6 mil vapour barrier (cost is $50 per 8’x500′ roll) and Tuck Tape ($6 per roll). A Passive House is often sheathed with 5/8″ OSB ($25 per 4’x8′ sheet) on the interior to serve as it’s vapour barrier or high-end Intello Plus vapour barrier ($320 per 64″x164′ roll) with the seams sealed with Tescon Profil/Vana tape ($45 per roll). It does not take much in the way of math skills to see that the latter option can get extremely expensive. But if you really want to ensure you hit that Passive House 0.6 ACH target, that’s probably what you need to do (the Tescon Profil tape is often used on the outside walls as well to seal the air barrier and windows/doors).
  • 3. We were not pursuing Passive House certification, so really there was no point in ensuring we hit 0.6 ACH. If you’re spending the money to have a Passive House consultant work with you at the initial design stage and you’re spending the money on the high-end Passive House certified windows, the special tapes and the extra insulation, you better make sure you hit 0.6 ACH or all of that expense will be for nothing. For us, if we made 0.6 ACH, great, if we didn’t, oh well.
  • 4. We were installing a wood burning stove and chimney. Although the stove itself is very high quality from Morso in Denmark, I figured this extra hole in the wall would likely negatively impact our airtightness. But we were not budging on not having a wood stove. We also had another extra hole in the wall for the water cistern in the basement, but again this could not be avoided.

All that being said, we did make every effort to design the house to be as airtight as we could. The dense-packed cellulose in the walls itself provides a high degree of air sealing on it’s own. We limited the penetrations into and out of the house by selecting a condensing dryer from Bosch and having an electric boiler (the only penetrations are the chimney stack, the water cistern pipe, and the HRV). We used a standard 6 mil poly for the vapour barrier with acoustic sealant at every seam. Each seam was also taped with standard Tuck Tape to ensure another layer of added protection. Around the windows and exterior doors we purchased and used the Teson Profil air sealing tapes to attach the vapour barrier to the frames. Although this tape is very pricy, it made sense to me to use it here as the greatest area of air leakage is often at the window frames and doors.

Now it was time to test the house.

The testing is done through a Blower Door test. “A blower door is a powerful fan that mounts into the frame of an exterior door. The fan pulls air out of the house, lowering the air pressure inside. The higher outside air pressure then flows in through all unsealed cracks and openings.” The test is repeated in the same way by drawing air into the house. “The auditors may use a smoke pencil to detect air leaks. These tests determine the air infiltration rate of a building. Blower doors consist of a frame and flexible panel that fit in a doorway, a variable-speed fan, a pressure gauge to measure the pressure differences inside and outside the home, and an airflow manometer and hoses for measuring airflow.”

Essentially it simulates wind blowing against the house in all directions at the same time. The test takes about an hour to administer with the tester taking multiple readings at different fan speeds both while depressurizing and repressurizing the building.

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While the test was running we also used an infrared meter to look at any hot/cold spots.

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A couple days later he sent us the results: 0.8 ACH at 50 pascals.

Right bang on our goal. Not bad. The guy who tested it said it was the tightest building he’d ever tested before.

I was happy enough with it, but a couple days later I happened to be standing beside the chimney on a windy day and I could ever so slightly hear a whistle through the pipe. I looked closely at the seams and saw they were not fully sealed. Damn!

We’d also had some crappy construction locks on the doors and I put my hand against them. I could feel wind there too! Double damn!

After sealing these leaks and a few other tiny ones we found, we did another retest a couple weeks ago. This time, the results were 0.72 ACH at 50 pascals. Not too shabby.

After talking to the tester, though, he thought that given the higher than expected discrepancy between the depressurized and repressurized values that maybe the vents of the HRV had opened slightly causing a skew to occur. He’d like to do one more retest in a couple weeks, thinking this would take it down to 0.65 ACH or lower. At this point, he’s doing it at no charge as he’s simply interested to see what the truest level of airtightness is.

For me, I’m happy to know that we reached almost Passive House airtightness values while still being as economical as possible.

*** Please see the UPDATED BLOWER DOOR TEST POST for the redo test final results! ***

Solar panels – Good for the environment, good for your wallet

Posted on by kent

It wasn’t enough for us to simply reduce our carbon footprint through building a super-insulated eco-house. We wanted to come as close to eliminating our footprint completely by working towards a net zero standard. The house envelope, airtightness, passive solar design, and thermal mass of the house, would all have the effect of reducing our energy consumption by 75-80%. The rest of our energy for heating, domestic hot water, and appliances was purely electric based, with the exception of our wood burning stove. We have no natural gas to our property – and to be honest, even if we did, we would not have hooked it up. Burning fossil fuels for energy, despite it’s current affordability, is not a clean energy source nor is it sustainable. Still, despite what some people say, electricity – at least in Saskatchewan – is not sustainable nor is it clean either. Our electricity comes from a power plant that uses a combination of coal and natural gas. Really, in one of the windiest and sunniest places in the world, you’d think we should be able to have some capacity to utilize renewable energy sources. Unfortunately, this is often a top-down decision in the government and sadly, both our provincial and federal governments are heavily financed through their strong ties to the oil and gas industries in this country (no matter how much of a downturn there has been in the markets over the past year) and there is no sign of this changing anytime soon

Until such a time that the collective elite decide to recognize the need to shift away from non-renewables, it will continue to be left to the grassroots movements and local homeowners to decide if they care enough to make a commitment to renewable energy – despite the upfront costs of doing so.

But these times are changing. No longer is it purely a decision of environmentalism. Now the argument of the economics of renewable energy can be made. Let me present this in layman’s terms (as I am, of course, a layman myself).

Our projections for electrical energy consumption:

Estimated yearly energy use (DHW, appliances, heating) = 14,508 kWh (including regular wood stove use for heat)

Cost per kWH hour of electricity in Saskatchewan = $0.1456

Our projected electrical costs per year = 14,508 x 0.1456 = $2,112.36/year or $176.03/month

We worked with a company in Saskatoon, called MiEnergy, in sizing a choosing which solar array system would best suit our needs. We decided to purchased a 6.2 kW PV array. There was the option to upgrade to the 9.3 kW system but we felt that this would definitely be oversized for us at this point. The 6.2 kW system will be slightly under-sized but we can always add on more panels at a later date if we so choose.

6.2 kW system delivers an average of 775 kWh/month = 9330 kWh/year on average

That provides us an immediate saving of $1358.45 per year ($113.20/month) in energy costs. Expanded over the course of a 25 years this delivers $33,961 in electrical savings at the current electrical rates. (I found an interesting article on the energy outlook in the U.S. – there has been a $0.04 cent rise per kWh from 2003 to 2013. Extrapolating that, conservatively, over the next 25 years we should expect an upwards $0.08-0.10 rise per kWh. That equals between $0.22-0.24/kWh. The projections from MiEnergy pegs the 30 years saving at $58,067).

If you take the cost of the PV panels and roll this into a 25 year mortgage at a current 3.19% interest, this only costs a meagre $110/month. So essentially instead of giving $113.20/month (currently, which will increase) to the government to cover our extra electrical bill, we will invest $110/month towards the PV panels on our mortgage. After 25 years, they are paid for and we have money in our pocket (not to mention the fact that we’ve saved 233,250 kWh of energy from being generated at a polluting power plant). That’s a win for us and for Mother Nature.

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If you want the facts and economics only, then disregard the story that follows. Of course, I wish my post, could be that short and simple. But as I’ve learned with building the house – something always goes wrong – no matter how bizarre, stupid or impossible it might seem…

The above photo is the after shot. After I received the phone call at 6pm on a Friday night from Saskpower (the electrical company) asking why a large steel beam had been driven directly through their power line?

“Uh… I don’t… know?”

You see there is this thing called: “Call Before You Dig.” It’s a free service that most places have that asks that you please call them to mark your underground power and gas lines before digging so that you don’t kill, maim, electrocute or otherwise dismember yourself. Unfortunately, as we learned that night, it is not a perfect service.

The solar company had called and had the power line (note, the singular word: line) marked a couple of days before the planned installation. Unfortunately, there were in fact, two power lines running into our transformer, one from our neighbours place to ours and the other running from ours to about 60 houses over the next number of miles. Well, you guessed it, they hit the one running to the 60 houses (that was not marked), knocking out their power for the next 8 hours. Oopsy.

IMG_3040When I showed up to the house, you could see the one line that was marked (as it was prior) with the solar panel racking system 4-5 feet away, then you saw where they had discovered the 2nd line, lying directly underneath the 2nd row of racking (not previously marked). The Saskpower guys though were very good, they realized it was not the fault of the solar company, nor mine, the line simply had not been marked by the Call Before You Dig people. They were just glad that no one had been hurt. They were able to restore power to the 60-odd houses that had been affected and the next day they were back out to splice and move our newly rediscovered power line.

(Incidentally, this was a total blessing, had they actually marked both power lines previously, we would not have been able to put the solar panels where we had wanted them. We would have been forced to find another, less ideal spot a much greater distance away).

By the way, we have had a number of people ask us why we did not choose to utilize a solar thermal system for water heating. Basically, it was because of this article and this article on Green Building Advisor.

SUPER-insulation! Airtightness! The staples of a passive house.

Posted on by kent

There are seemingly innumerable weighs of building a super-insulated home. Once you venture outside of the conventional 2×6 walls with 1-2″ of EPS foam, there suddenly opens of a plethora of options. I won’t go into as I’ve talked about it before, in us choosing super-insulated walls system and the double-stud deep wall framing. Now what you put between those walls is just as important as how you construct those walls. In our case, we chose to use dense-packed cellulose.

Cellulose insulation is a made from recycled newspaper or other wastepaper and treated with borates for fire and insect protection (taken from GBA). Dense-packed cellulose is really, just what it sounds like: They pack it like crazy into the wall cavity – but not too crazy. In fact, the ideal balance between too loose and too dense is about 3.5 lbs per cubic foot. If it is too loose it will settle and result in poor insulation over time. The denser it is the more resistance to air leakage (the vapour barrier obviously reduces this further) and the better the insulation. However beyond about 4 lbs per cubic foot of density you are at risk of blow-outs (or the drywallers will not be able to work with your crazy wavy walls).

At 3.5 lbs per cubic foot and with 16″ thick walls, our R-value is a whopping R56 for the exterior above-grade walls!

We contracted a company, Westcan Insulators Inc., who has extensive experience with super-insulated homes and a wealth of knowledge in energy efficiency. At our preliminary meetings they provided us with so much valuable information (have preliminary meetings with all trades presents – it truly is invaluable). It was so reassuring to have them on board, as really in building an energy-efficient home, the insulation and airtightness are the most important aspects. If you don’t have this right, you really don’t have anything.

As Rob Dumont said: “Anything that has moving parts will fail; in fact, it must fail, because there is no such thing as a perfect bearing.” Therefore, passive systems are always better than active systems and insulation and air sealing, if done well, will have the greatest return (for the lowest cost) over the lifetime of the building.

So here’s how the process worked:

On day 1, the crew came in and wrapped the walls with InsulWeb, a mesh that holds the dense-packed cellulose in place while spraying. They go through a buttload of staples to hold this onto the studs. They have to put a staple every inch along every stud, so you can imagine how many staples that would be. Crazy.

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The next day, they bring out a big 5 tonne truck and using a 3″ wide metal hose they make a hole at one-third and two-thirds of the way up each stud bay. They then proceed to essentially filling the walls with the entirety of the truck. In actual fact, they unloaded about 6000 lbs of insulation into the walls alone (holy crap!).

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Here is a close-up shot of the cellulose and penetration. You can nearly read the newsprint.

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The next day came the vapour barrier and air sealing. This actually took the better part of five days for them to complete, but they did an excellent job (by the looks of it – we will really find out when we test it with a blower door in the next few weeks).

Airtightness is really equally as important as the insulation – perhaps even more so. Air leaking into and out of a building is not efficient no matter how much insulation you have in the walls. They used 6 mil poly for the vapour barrier with acoustic sealant at every seam. Each seam was also taped to ensure another layer of added protection, though truthfully this is probably unnecessary (from what we have been told, with this insulation alone, without the vapour barrier, would surely pass the R2000 airtightness requirement of 1.5 ACH @ 50 pascals), but it’s not hard to do and once the drywall is up you can’t go back and add more.

Around the windows and doors though we spent a bit of money and purchased Tescon Profil tape from 475 Building Performance. The stuff runs at $45 per roll, which is certainly a premium price versus the $9 per roll of good ol’ Tuck tape (the latter of which we used around all other seams). However between the walls and the windows/doors, there isn’t the layer of protection of the dense packed cellulose insulation (although they did spray foam around each window and the rough opening), so we felt the extra price could be justified here (to do the whole house in the Tescon Profil tape would be simply cost-prohibitive [although some people do it]. For the marginal gains you “might” make in airtightness, you would never save enough money on the long-term to justify that huge upfront cost, in my humble opinion).

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Expensive fancy tape.

Main Floor Concrete

Posted on by kent

We were very happy with how the basement concrete slab turned out. Tyco Concrete had come through for us on short notice and they had done a really nice job. So one week later we had them come back in to do a second pour, this time for the main floor. We had really debated about how we would like to finish the main floor concrete though despite months of reading and looking.

I should digress for a moment and simply state our reasons behind the concrete floor in the first place:

  1. Thermal mass – thermal mass is a the ability of a material to absorb and store energy (heat in particular). For passive solar heating in the winter months, the sun shining on the concrete will act like a battery, gaining heat during the day, and allowing it to release the heat in the evening. You could use a tile or brick to similar effect. A large brick or stone wall would also work, but you need the sun shining on it. Conversely, in the summer and “shoulder” (April and October) months you really don’t want the sun shining on the thermal mass as this can lead to overheating (thus the importance of passive shading and overhangs).
  2. In-floor heating – we still need a heat system. It is true that our thermal mass is not quite as good as if it had no in-floor heat (a colder mass will heat MORE than a mass that is already pre-heated) – however who wants to walk around on a cold concrete floor in the morning, honestly?
  3. Concrete is sexy.

Okay so now that that is cleared up, we had to decide on how we would like to eventually finish the floors. We had already decided that acid staining and dyeing the concrete was really not our thing – much too fancy-pants for us. That basically left us with two options: power trowel (same as the basement) or grind and polish. Both looks we really like.

Grind and polished concrete – not our place

The grind and polish look is something I really like. You need a concrete grinder machine with diamond discs starting with very rough grits of 80 and 120, which grind the top layer of concrete off exposing the pea gravel aggregate that sinks to the bottom and progressing up to finer and finer grits. Eventually getting up to 800, 1200, 2000 grit discs that give a highly polished look to the floor. You get a lot of interesting variation and different colors of the pea gravel coming through (although some people specify all grey or black pea rock if they want something more consistent). There is a couple downsides with this for us though. Firstly the concrete topper they were going to pour was only going to be 1.5″ thick, which is pretty darn thin. Although you are only taking about 1/8″ or so off the top, we had 1/2″ PEX in-floor piping and metal concrete mesh overtop – grinding too much off could be a horrible thing. We had seen this first hand – a good friend had built an eco-house in town and wanted a ground and polished concrete floor. Unfortunately the contractor ground off about 1/4″ too much. It looked great initially, but the layer of concrete over the in-floor heat was so thin that in the next few weeks the concrete started to crack badly following the pattern of the in-floor lines… It looked so bad. On a thicker floor you’d have nothing to worry about, mind you. But needless to say I was a bit paranoid of that risk. The second consideration is that you need to grind and polish before drywall as it makes a crazy mess. And you can’t grind and polish until it has cured for one month. That would mean that we would have to put the interior on hold for a month which we really did not want to do.

The other option was to simply power trowel the main floor, same as the basement. We have seen this look a lot in some more modern homes and I really like the simplicity of it. It is not complicated at all and is in fact the simplest, cheapest and easiest way to go (pour and trowel is about $2.50/sq.ft completed while the the grinding and polishing cost would be an additional $5-6/sq.ft above and beyond). You pour floor, power trowel the crap out of it and call it a day (in 28 days you can seal it, buff it, wax it, whatever). As I said we liked how the basement floor turned out, particular the very “swirly” areas, as my wife calls them. I hoped that we could make the floors slightly different then the basement floor still though. I looked into the possibility of adding a bit of black pigment to darken the grey slightly – however I abandoned this idea after I was told the pigment dries the concrete faster and can lead to an uneven finish.

Eventually the decision came down to, what is the simplest option? Through this process we have found ourselves periodically down a rabbit hole wondering how we got here and how everything became so complicated. Our answer in those situations, or when we’ve debated about two or three different things is – simple is always better. The more complicated, the more things can go wrong.

So I told the concrete guy, “finish the concrete just like the basement – only, more swirly please.” (He told us that the metal blades of the power troweled as what make it swirled and darker, but troweling longer and on a higher speed for the blades, they can darken the concrete more).

The morning of the pour was crazy again, our builder did not realize they were coming so early with the concrete truck and he’d left a bunch of stuff around the house. I received a text at 6:30am from the concrete guy – “someone has to get over here and move all this shit – truck is here.”

IMG_2982Fortunately we are living very close right now so I threw on some clothes and was out the door. We frantically (concrete starts to cure as soon as it leaves the plant – being 30 minutes from the city, every extra moment counts) moved a trailer, two big garbage bins, scrap wood, plywood and all sorts of junk. Meanwhile the rest of the concrete crew was even more frantically throwing down the concrete mesh (which provides structural support, like rebar, in thinly poured floors like ours). This stuff was crazy heavy and looked so cumbersome to work with, but these guys were pros, they had the whole floor laid and secured in about 20 minutes.

And so the pour began again. I could not stay and watch and truthfully, I did not want to see it. Seeing that grey/brown sludge of mud being rolled in and dumped on the floor simply made me nervous. I just wanted to see it pretty at the end.

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When we got home all was quiet again. We went to the back door and peaked our heads in.

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So swirly!

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So very swirly!