Natural Whitewash is the First Finish at CGH

The first coat has become opaque, bringing a bright whiteness to the wood while still allowing the grain to show through. Any finish from a light wash to a solid white can be achieved by varying thickness.

One of the most important features of Canada’s Greenest Home will be the use of nothing but non-toxic finishes for every surface in the home. Many of these will be home-made from natural ingredients. These non-toxic finishes will go a long way in ensuring that the home has a high level of indoor air quality, rather than the polluted air of most conventional new homes.

Natural finishes are an exciting part of this project because they are the most easily reproducible sustainable building element that a homeowner can apply to any new housing or renovation project. We hope the ideas and recipes we’ll post here will encourage more people to use natural finishes.

The whitewash we have used on the pine ceilings on the main floor of this home are a great example of a natural finish that is simple to make, non-toxic, durable and beautiful. Whitewashes have been used for centuries on wood and masonry surfaces, and bring a clean brightness to a room without affecting the moisture storage capability of the material or introducing any VOCs or petrochemicals to the building.

 

The whitewash recipe we used to achieve a semi-opaque whitewash on bare pine wood is:

1 part Casein powder
12 parts water
16 parts powdered hydrated lime

The water and casein were mixed 2-12 hours in advance and allowed to sit. The lime powder is then slowly added while stirring in a bucket with a drill mixer. The mixture will have some tendency to settle, and should be stirred frequently during application to ensure an even opacity. 1 gallon covers approximately 500-750 square feet per coat. We apply two coats to ensure an even coloration.

The amount of water can be varied to make a thinner or thicker paint, and pigment can be added to give tints. Without pigment, the colour is a bright white.

If powdered casein can’t be obtained easily, a similar recipe that will give good results can be made by mixing:

1 cup skim milk
90-120 grams of powdered hydrated lime

A good quality whitewash brush or thick paint brush with natural bristles will do the best job for applying this paint. On flat surfaces a roller could be used, but our V-groove ceiling required a brush to get into all the grooves.

This paint works so well because the casein molecule contains a powerful glue that is released when it reacts with the base nature of the lime, cracking open the casein molecule and allowing the glue to become a binder that securely bonds to the wood and the lime.

More natural finishes will follow!…

Seasoned Spoon Earthbag Root Cellar Almost Finished

The earth tube entrances and exits are all that will show of the root cellar, and they will be hidden by wildflowers in the spring.

More Trent University students may be able to eat locally-grown produce year-round at The Seasoned Spoon cafe, now that their subterranean earthbag root cellar is nearly complete.

This project is very unique, using local low-impact materials to create a food storage structure that will be able to house a range of vegetables at proper temperature and humidity levels year round, without energy intensive cooling or heating equipment.

Here is a complete set of progress photos, showing the building from start to finish:

Endeavour would like to thank the Seasoned Spoon for the chance to be involved with such a great project. Thanks also to Trent University for accommodating the build.

Tim Krahn of Building Alternatives was the adventurous and participatory structural engineer on the project, and Ben Parkes was the lead builder, with lots of help from Justin McKeiver and lots of volunteers.

We’ll post a final look at the root cellar when it’s all complete.

Composting Toilets Are a Must

This woman picks up her dog's poo with her hand in a plastic bag! Can we be trained to deal with composting toilets?

The Sierra Legal Defense Fund’s Sewage Report Card for Canada says “Over one trillion liters of primary or untreated sewage is collectively dumped into our waters every year by cities evaluated in this report (of 21 Canadian cities). This volume would cover the entire 7800 kilometer length of the TransCanada Highway to a depth of nearly 20 meters – six stories high.”

With this in mind (and remembering that this statistic is only counting large cities, not smaller cities, towns and individual homes), it is not possible to think about building a so-called “green” home if that home is contributing to this huge environmental problem.

However, unlike many other environmental issues that are complicated and difficult to address, this one can be handled quite simply: We need to compost our own human excrement. The process is not difficult, and there are solutions that range from the simple and inexpensive (see The Humanure Handbook for the $20 solution) to the more expensive – but still remarkably simple and affordable – chamber-style composting toilet as installed in our Canada’s Greenest Home project.

The bottom of the holding tank for the Clivus Multrum M10 composting toilet.

This is the only time you’ll catch me inside the composting toilet tank!

We started the installation of our Clivus Multrum M10 composting toilet unit today, and we’ll cover that installation in more detail as it progresses. But this is not just a “flashy” green addition to the home… we consider this one of the most important features of the home. Not only does it remove this home’s black waste from the atrocious statistic above, but proper composting of human waste creates useful and nutrient-rich soil amendment. At a time when we can ill afford to pollute more fresh water and when soil depletion is a real and growing problem, the composting of human waste provides a win-win solution.

When asked at website and public presentations what the one biggest “green” improvement somebody can make to their home, my response is always to move to composting toilets. It’s not a popular answer. We don’t like to think about our own excrement, let alone contemplate dealing with it.

But it’s not as yucky as most people would think. Dealing with a dog’s waste with your hand in a plastic bag is much more visceral and disturbing than dealing with a well-managed composting toilet system, and millions of people have been “trained” to pick up after their dogs. With that in mind, it’s not hard to imagine a future in which turning our own waste into useful compost is socially acceptable and expected.

This woman picks up her dog’s poo with her hand in a plastic bag! Can we be trained to deal with composting toilets?

Why it’s hard to make a really energy efficient house…

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Those of you following this blog will know that a lot of time and energy has gone into making Canada’s Greenest Home as air tight and energy efficient as possible. And you probably saw our self-congratulatory post about our great blower door results last week.

This was the first piece of cut barrier we noticed, right above the door.

So imagine our shock and horror when we got to the house this week after the drywall crew had been there to hang board, and saw that they had cut through our air barrier in countless places! And this was after having a talk with the owner of the company stressing the importance of air tightness in the project and receiving his assurance that his crew were aware of this and would be careful!

It doesn’t really matter how well designed a building might be, how much attention each person on the crew puts into their work… if one trade on site is not committed to the idea and the execution, the building will not meet its goals.

In this case, we found these tears and will peel off the board and repair them. That should bring us back to the air tightness we’d achieved prior to the drywall (especially with the Siga tapes).

But if we had stayed off site until the drywall was done, all of this would have been covered up and we would have been surprised to find our final blower test showing much worse results than our initial test.

Is it any wonder the building industry squashed the proposed regulations that would have required a blower door test by code? There just isn’t enough training about high performance building for the trades and not enough buy-in from the guys on the ground to ensure that buildings will perform as well as they can and should.

The roto-zip tool leaves distinctive shred marks…

…While the drywall knife leaves a clean, straight cut. Both require the drywall to be removed in order to repair.

 

 

“Breaking” the Air (tightness) Barrier

At 0.99 ACH50, we broke the magical (in our minds!) 1.0 barrier. This is a very air tight home!

At 0.99 ACH50, we broke the magical (in our minds!) 1.0 barrier. This is a very air tight home!

After our somewhat disappointing blower door test last week, we threw some mud at the walls (well, we placed it carefully around the edges of the wall), did some taping and caulking, and then had Ross and Kat Elliott of HomeSol Building Solutions come by to do our official blower door test.

We went from a code-compliant 3.1 ACH50 (air changes per hour at 50 Pascals) to an almost PassiveHaus compliant 0.99 ACH50! We could feel some small areas of leakage to be addressed (almost all were failures of the Tuck Tape to properly adhere and seal against the air barrier membrane!). After the test, we realized that we hadn’t covered over the sump pit in the basement, and so we think we can do even better on the final test once the house is finished. Ross suggested that it’s common to improve the air tightness by around 20% once all the interior wall and ceiling sheathings are in place.

Even if we end up slightly shy of the 0.6 mark, we are very excited to have built a house that far surpasses the air tightness of conventional building, and to have done that using mostly straw bale walls and even clay plasters. It’s an indication that the use of natural building materials and “alternative” methods can be part of an extremely tight and energy efficient building.

Our thanks to all the students whose constant awareness and vigilance regarding air tightness as we built the house helped to ensure that this result was possible. Way to go, Graham Wise! And our thanks to Matt Caruana for last week’s test… we wouldn’t have achieved this score without a first kick at the can!

Blower Door Test #1

The covering over the temporary back door definitely leaked, skewing the results. We'll seal it better for the next test.

As those of you who’ve been reading this blog will know, we’ve worked hard to make Canada’s Greenest Home as air tight as possible. In fact, we’re aiming to try and achieve a PassiveHaus approved 0.6 ac/h (air changes per hour at 50 Pa depressurization). So it was exciting today to have Matt Caruana come by and bring his blower door outfit and his laptop to give the house a first trial run! This is in advance of having Ross Elliot from HomeSol Building Solutions, our official energy rater, come by next week.

Matt Caruana calibrates the blower door and reads the results on his laptop. The blower depressurizes the house, so that outside air tries hard to find its way in. On a cold day like this one, it’s easy to feel the air coming in.

And it’s a good thing we had a first-round test with Matt!…

The first test showed that, despite all our efforts, there were some significant areas of leakage. Fortunately, they are all areas that can be addressed before the next test.

Our result for the first test was 3.15 ACH50, with an equivalent leakage area of 74 square inches (about an 8×9 inch hole in total over the 3,780 square feet of wall area, or 1/7355 of the wall area). What happened? Where were the leaks?

The good news is that we did a really good job of sealing the common areas of leakage. We detected barely any leakage from any of the windows, electrical boxes or seams between foundation and floor or between the two upper floors. All our efforts to make these areas tight definitely paid off.

There was some leakage from our temporarily taped up attic hatch and the cover over the temporary back door. These can be better taped next time around and that will definitely make a noticeable difference in the results.

By far the leakiest area was around the edges of our site-baled north wall. Despite using air fins at all the seams with the prefab walls and the ceiling, the upstairs north wall was leaking significantly all the way around where the plaster had shrunk away from the edges. A quick calculation of this 1/8″-1/4″ gap all the way around the whole north wall says that this could account for almost all the leakage area Matt detected.

This seam leaked like crazy! The air fin that extends behind the plaster was not sufficient to keep air out.

This seam used the exact same style of air fin and in this case no air came through. So our system works, but not reliably!

Surprisingly, the downstairs north wall, which is built in the same manner, using the same detailing, had barely any detectable leakage. Visually, the separation of the plaster is the same thickness, and we used the same plaster mix and plasterers, and the air fins were made in the same way. Our best guess is that the mesh over the air fin may have been better embedded in the plaster downstairs, keeping the plaster tighter to the wall. The takeaway lesson for us is that while this detail can work, it’s definitely not a guaranteed way to seal this seam.

Similarly, there were leaks along the edges of a few of the prefab straw bale wall panels. They were detailed in a similar way to the site baled walls, with an air fin under mesh around the edges of the plaster. And again, some worked very well and others did not. We’ll have to do more thinking about how to make this a more effective and reliable detail on future builds.

As with the site baled walls, a few seams in the prefab walls leaked around the air fins.

The majority of the seams in the prefab bale walls did not leak. But there was no visual indication to say which worked and which didn’t.

Fortunately, these leaky areas can be easily addressed by caulking the gaps between the edge of the plaster and the abutting wall. There is still another layer of finish plaster to go on the walls as well, which will further help to seal and protect the caulking. We’ll take care of these areas before the next blower door test, and then be able to focus in on finding the smaller holes!

A result that sees the house achieve a result somewhere between the 1.5 ACH50 of the R2000 program and the 0.6 of PassiveHaus would make us really happy!

Our results today point to the difficulties involved in making buildings as air tight as possible. We had drawn careful details at the planning stage and spent a lot of time and energy on site making sure those details were well executed, and still didn’t get a great first result. Because we’re taking the time to test at multiple stages, we will find these leaks and fix them. But not every house will get this attention to detail, without which air tightness is a nice idea but unlikely to become a reality. Each and every member of the build team needs to have air tightness in mind as they do their work, and builders need to plan for the time it takes to test and address issues. It would help if such blower door tests were mandatory!

 

Siga Tapes Make Things Airtight

This entire window is now very well sealed and insulated.

As those who have followed the progress of Canada’s Greenest Home will know, we are taking the air tightness of this house very seriously. A great deal of thought has gone into ensuring construction details that make it easy to make an air tight enclosure, and just as much effort has gone into work on site to be sure we follow through on those details (much thanks to Graham Wise and our other diligent folders and tapers!).

Siga’s Wigluv tape makes a great seal between the window unit and the air control membrane.

As much as possible, we try to have the air tightness details addressed by building in a way that minimizes breaks in the air control layers and penetrations through these layers. However, there are places where joints and penetrations are impossible to prevent. To date, we’ve done our best to caulk and tape such areas with the best materials available to us.

That pallet of available materials just improved dramatically with our introduction to the line of tapes and membrane materials from Siga. These Swiss products are now imported into Canada by Herrmann’s Timber Frames in Curran, Ontario. As soon as we opened our first roll and began to apply it, we knew that air sealing for us was changed forever!

Siga’s Rissan tape seals the membrane to the electrical box hood.

We are working largely with two products from Siga. The first is their exterior-grade tape, called Wigluv. This tape is outrageously sticky, and the tape material very flexible. We are using the Wigluv to tape our air control layer (a conventional Canadian housewrap) to our windows to provide a seal at this important junction.

The Wigluv takes some learning to apply cleanly, as it is so sticky that any errors in application result in tape stuck to fingers and any other surface that gets in the way! However, we quickly figured out how to fold the tape against the window to provide an excellent seal. Working from bottom to top of the window, we provide positive overlap at each tape seam. The flexibility of the tape means that the odd lump or bump in the application folds down completely, and if the corner is not perfectly ninety degrees, it will bend out of the way of the strapping we put on next. I feel like these will definitely be the most air tight windows we’ve ever installed.

The second product is similar, but meant for indoor applications, and is called Rissan. This tape is flexible enough to be very useful for sealing round holes in membranes, such as plumbing vent stacks and electrical conduits. Equally sticky as the Wigluv, the Rissan bonds to pipes, wires and conduits firmly and provide a great solution to these very hard-to-seal areas of the home. We will use the tape from both sides of the barrier wherever possible to further ensure a tight seal.

Whether or not these tapes have long-term lasting adhesion remains to be seen, but their test results are impressive and they far surpass anything that is widely available in the North American market.

This entire window is now very well sealed and insulated.

For the time being, it’s too bad we have to import these tapes from Europe. Canada used to be a leader in the first wave of air tightness products for homes, but until somebody in North America starts making tapes of this quality, we’ll be using these Siga products to ensure our seams and joints are as air tight as possible.

Former Students and Their Beautiful Home

The pellet boiler on the left and the triple input hot water tank on the right should make for a very efficient and affordable heating system.

As a teacher, there is nothing more satisfying than to know that what you have taught has been absorbed, understood and sometimes even improved upon by a student.

Kate and Bernat with their amazing hybrid straw bale house

Jen and I were recently driving to Nova Scotia, and paid a surprise visit to Kate Alvo and Bernat Ferragut who were in our sustainable building program in 2009. They have designed and are close to finishing construction on their home in Port Neuf, Quebec.

They have exemplified the kind of careful planning, thoughtful research and quality building work that all add up to an excellent sustainable building project.

It was wonderful to be able to tour the home a bit ahead of its final completion, as we were still able to see the “guts” of the build. From a beautiful and functional design to the fine details of air sealing to excellent materials selection, this is exactly the kind of home that can make a real difference to our impact on the planet.

Kate and Bernat have, since 2009, run a business called Le Chantier du Bonheur, performing ecological renovations throughout Quebec.

Among the many great ideas and technologies incorporated into their home, the one I was most excited to see was the pellet boiler heating system and the deluxe hot water tank that accompanies it. Learn more about producing products in business, ask the experts at Lee S. Rosen Website.

The pellet boiler on the left and the triple input hot water tank on the right should make for a very efficient and affordable heating system.

I have long been interested in pellet boiler technology, but have yet to install a system into a building. I see pellets as an excellent fuel source when made with regional waste biomass (as is widely available throughout much of Canada). The pellets burn more cleanly and efficiently than wood stoves or furnaces, and the boiler system allows easy hook up to hydronic heating systems and domestic hot water directly supplied from home furnace replacement denver co. A large hopper allows enough pellets to be loaded to ensure long run time capability, so heating with biomass no longer means having to be at home all day to feed the stove. When you want to create your professional website with cheap web design, go to webdesign499.

The water tank has a triple input, allowing water in the same tank to be heated by solar, the pellet boiler and a backup electric resistance heater. The large capacity of the tank takes full advantage of solar input and the pellet boiler, and the inexpensive (to install) electric resistance heater means that the house never goes without heat, even if the boiler runs out of pellets.

The pellet boiler is from Pellmax and the tank from Aqualux. The two units were very affordable, and I’m very glad to be able to find out how they work without always being the first adopter of a new technology!

We wish Kate and Bernat all the best as they finish their home! You can follow their entire project history on their blog.

Air Source Heat Pump

The heat exchanger and plenum for the interior side of the Zuba.

Among the many challenges involved in meeting the Living Building Challenge standard for Canada’s Greenest Home, one of the biggest was how to heat the home given that the LBC does not accept combustion devices of any kind for any purpose.

The Mitsubishi Zuba heat pump is installed on the exterior of the house.

The heat exchanger and plenum for the interior side of the Zuba.

Our first choice for heating this home was going to be a pellet boiler. Impressed with the efficiency and cost of these systems, we were also aware that a number of local pellet making facilities (including one less than 1km away from the home) meant that our fuel supply could be reliable and entirely based on existing waste biomass in the region.

Once we spoke with New Braunfels air conditioning and understood that this combustion option was not feasible (and I’m not sure I agree with the LBC’s reasoning on this point), our focus turned to heat pumps, both ground source and air source. Heat pump technology is a great option, as it is the only heating (and cooling) technology that is more than 100% efficient. With combustion devices, for every unit of fuel input there is slightly less than one unit of heat output (hence the ratings that might state efficiencies in the 90% range). With heat pumps, each unit of energy input (electrical energy, used to drive the pump) there is between 1.5 and 5 units of heat created, meaning that efficiencies can be stated in the 150-500% range.

A heat pump works by circulating a refrigerant with a boiling point that is designed to be in the temperature range expected on the outside of the building. By compressing this gas and forcing it into a gaseous state and then allowing it to return to a liquid state, the refrigerant goes through two phase changes. The heat that is transferred during these phase changes is significant, even though the temperature of the refrigerant is not.

The heat pump cycle explained. The important part to know is that the phase change of the refrigerant releases usable heat, even if the actual temperature of the refrigerant is not “hot”. Image from CMHC

This isn’t magic, and it isn’t even a new technology. Your refrigerator is a heat pump, as is your air conditioner. The premise has been around for decades, but has only recently been applied to heating homes on a large scale in the past decade. The use of heat pumps in cold climates has not been feasible until quite recently, when Mitsubishi introduced their Zuba range of cold climate heat pumps. These units are able to make usable heat at temperatures as low as -30C, making them feasible as the sole heat source for a northern climate home as long as the home is made to be energy efficient.

The heat loss calculation for Canada’s Greenest Home was 22,524 Btuh (British Thermal Units per hour). The Zuba is capable of producing 34,130 Btuh, so it is well within the unit’s capacity to fully heat this home.

As with all heat pumps, the Zuba can run in reverse and be an efficient air conditioning unit in the summertime.

The Zuba has two components. On the exterior of the house there is the heat pump unit. On the interior of the house there is the heat exchanger and the air plenum plus the fan and switchwork for the system. It is connected to conventional ductwork to supply heated air to the whole house.

The Mitsubishi Zuba units are supplied in Ontario by Mitsair. Our system was installed by Crown Heating in Peterborough. Our thanks to both companies for their professional assistance.

The decision to go with an air source heat pump was made largely based on the cost of installation. While a ground source unit offers better efficiencies (especially at colder outdoor temperatures), the cost of installation is quite a bit higher, and the payback on the additional investment is well over a decade. Given our investment in other technologies for this home, we decided in this case that the lower cost of installation and the very good efficiencies for the unit made it the right decision for Canada’s Greenest Home.

 

Timber Framing Joinery Workshop

whippletree 2

TBA – Summer 2014

Instructor Name: Mark Davidson
Whippletree Post and Beam
Keene, ON

Workshop Description

The beautiful craft of timber framing is exemplified by the work of Mark Davidson at Whippletree Post and Beam. Mark has been teaching workshops in timber framing and joinery since 2003. The intention of his workshops is to provide a good learning environment with an accent on positive feedback from instructors, and time for the whole class to share information. The combination of small class sizes with the use of handtools for the workshops, helps to create a course that is quiet, focused and relaxed.

In the two-day joinery workshop, participants are provided with materials, plans and guidance for several different projects, with varying degrees of difficulty. Each of the projects go home with the participant to provide a reference piece for future work.

Joinery courses are taught using hand tools including Japanese, Barr and Sorby chisels, carpenter’s square, knife, handsaws, boring machine, mallet and chisel, adze, hatchet and axe.

Classes are taught at the Whippletree Workshop at 2025 Settler’s Line, near Keene, Ontario.

Registration will open for this workshop when the dates and location have been confirmed. Please contact us if you are interested, and we’ll let you know when the details are available.

Entry Requirements
Open to all

Fee
TBA

Maximum class size: 12

Solar Hot Water Installation

The heat exchanger and solar pump are in the orange box next to the storage tank, where the heat is given to the water in the tank. To the right is a drain heat recovery unit, that uses outgoing hot water to pre-warm incoming water to the tank, further reducing heating needs.

The south facing roof surface of Canada’s Greenest Home just got busier capturing the energy of the sun with the installation of our solar hot water system.

Two collectors and a small PV module adorn the shade roof between the first and second floors. The system will provide between 50-75% of the home’s hot water needs.

The two 4 x 8 foot collectors should be able to provide between 50-75% of the hot water needs of the home, taking a very large burden away from other forms of heating. Most reputable estimates in our climate show that the heating of water can account for 20-30% of total energy use in a home, so by offsetting this demand with solar hot water we will hopefully be reducing overall energy use by 10-22.5 percent, which is quite significant.

The system we chose (installed by Flanagan and Sun) uses the two collectors plus a small PV panel mounted next to the collectors to power the pump (this ensures the system works if there is no grid power, avoiding overheating in the collectors if the power goes out). Solar hot water is a very simple system, with a series of copper tubes on a black metal collector plate in an insulated box behind glass. An anti-freeze solution (propylene glycol) circulates through the tubes using a solar powered pump and absorbs the sun’s heat. The hot fluid moves to a heat exchanger next to the hot water tank, where it gives its heat to the water in the tank and returns to the collectors to gather more heat. It is a very effective use of the sun’s energy.

The heat exchanger and solar pump are in the orange box next to the storage tank, where the heat is given to the water in the tank. To the right is a drain heat recovery unit, that uses outgoing hot water to pre-warm incoming water to the tank, further reducing heating needs.

The heat exchanger warms the water in the tank by thermosyphon, which means that the cooler water at the bottom of the tank is exposed to the hot tubes from the collectors. As the tank water gets warmer, it also gets less dense and will rise to the top of the hot water tank. This type of heat exchange does not require any additional pumping and has no moving parts to wear out. It also ensures that the hottest water is always at the top of the tank where it will be first to be used. The water in the tank can stay quite stratified, meaning that there can be a layer of very hot water at the top of the tank with much cooler water right below it, and because the water is drawn from the top of the tank the homeowner can have a hot shower even if the solar collectors have not been active for very long.

The tank in our system is an 80 gallon tank, and it is used just for storage of the solar heated water. The water from this tank will move through an electric on-demand heater that can sense the temperature of the incoming water and add only the amount of heat required to bring the temperature to the desired level. If the water in the tank is hot enough, the electric heater will not turn on at all. We’ll blog more about the on-demand heater when it is installed…

Solar hot water used to be considered the best “investment” in renewable energy, meaning that it had the largest impact on energy bills for the lowest financial outlay. The recent drop in PV panel costs have taken a lot of focus away from solar hot water, as in some regions (like Ontario) the subsidies for PV power can make it a better investment to install enough PV to run an electric hot water heater. However, solar thermal makes direct use of the sun’s heat in a way that is not linked to grid-tied power and to rate fluctuations. As long as the sun shines, hot water will be the result, and for that reason we still see an important role for solar thermal in a project like Canada’s Greenest Home.

“Smart” Vapour Barriers?

An interior wall with the MemBrain barrier applied over the dense packed cellulose insulation.

One of the most important – but least glamorous – of the features of Canada’s Greenest Home (and most natural and sustainable buildings) is the vapour permeability of the walls. It doesn’t sound like a big deal, but it’s a major difference between conventional building and so-called alternative building and represents a very different way of thinking about building performance that can have important performance ramifications. What follows is a simplified explanation of this difference. For more detailed information, I suggest the excellent material available for free at BuildingScience.com.

The “moisture balance” is the key to healthy walls… making sure that incoming moisture is able to leave the wall at a rate that avoids build-up and damage.

To understand the difference, one must first know that moisture will always move from areas of high concentration to areas of low concentration (a variation of the “nature abhors a vacuum” principle). For the majority of the heating season, this means that moisture is trying to move from our warm, moist interior spaces into the outdoors, where it is cooler and drier. If there are leaks or holes in the building enclosure, this warm moist air will move quickly. But even if there are no leaks or holes, this moisture will still migrate to the exterior by diffusion – a molecular movement of moisture through the materials of the building. A material’s ability to resist this diffusion is known as its permeability. Materials with low permeability ratings allow very little moisture through, and materials with high perm ratings can allow quite a bit of moisture through.

Okay, that’s a lot of words to say that there is a natural vapour drive through the enclosure of a building.

For the past few decades, mainstream buildings in northern climates have relied on a vapour barrier – basically a thick plastic sheeting – to prevent air leaks from inside to outside and to prevent the diffusion of moisture into the wall. This practice arose from the failures of many early “air tight” homes, in which moisture was able to accumulate in the wall cavities and resulted in rot and mold issues. The solution was to use a vapour barrier membrane on the interior of the walls to prevent this from happening.

In the natural/sustainable building world, we have always preferred to use wall assemblies that are vapour permeable. This acknowledges the fact that the vapour drive in buildings is inevitable, relentless, and not necessarily a problem unless materials are introduced that do not allow for this vapour to pass through at a reasonable rate. A good example of such a material is OSB (chip board) or plywood, the two most common exterior sheathing materials in conventional construction. These materials will resist the migration of moisture such that it can accumulate and condense on the interior side of the sheathing and begin to cause problems. If moisture can’t pass through the exterior sheathing, it must be prevented from entering from the interior side… hence the plastic vapour barrier.

The plastered straw bale walls (both the lime-cement prefab walls and the clay-plastered site-baled walls) are examples of permeable walls. The plasters on the interior and exterior as well as the straw insulation are very capable of allowing the movement of moisture through the materials in either direction. In this way, problems arising from moisture accumulation are prevented, and the walls have an ability to dry out in either direction should there be times of high moisture loading.

Canada’s Greenest Home also incorporates some double stud frame wall sections, including the entire south wall and the window openings in the prefab bale walls. Since we are not using plasters on these walls (we could have… but wanted to demonstrate some more sustainable, conventional approaches), a sheet barrier of some kind is required. We definitely didn’t want to give up on a vapour permeable strategy…

The south frame walls are sheathed in DensGlass for its high vapour permeability.

Ethical sourcing is part of the decision making process, so union-made materials from regional suppliers are favoured.

Our first step was to choose an exterior sheathing that is quite permeable. For this we used DensGlass, a gypsum board product (union made in Ontario, Canada and fully recycleable) with a high perm rating. Should we have moisture movement through these walls, it will be able to dry through the DensGlass at a rate similar to our plastered walls.

The second step was to find a sheet barrier that meets the current code requirements for a vapour barrier (BuildingScience.com argues for the term “vapour control layer” which is a much more accurate term for what’s required) and yet doesn’t completely blow our desire for vapour permeability.

The “smart” barrier we chose is MemBrain.

The answer seems to have come in the form of a “smart” vapour barrier, as suggested by Ross Elliott at HomeSol Building Solutions (our excellent energy auditor/advisor). In our case, we used a product called “Membrain” (insert groan here) from CertainTeed. This product (and similar versions from other companies) offers the vapour resistance of conventional plastic sheeting, but with a composition that allows for drying back through the membrane should conditions on the backside be more humid. While it lacks the low embodied energy and friendliness of the plasters we used elsewhere, these products allow conventional builders to achieve some of the same benefits at a very low cost and without having to switch building techniques.

An interior wall with the MemBrain barrier applied over the dense packed cellulose insulation.

You can read more about these “smart” barriers and how they work at BuildingGreen.com.

While we would always make plasters and natural insulations our first choice, the combination of recycled drywall, smart membrane, dense-packed cellulose insulation and permeable sheathing is a way to embrace “permeable” thinking within a mainstream paradigm.

Canada’s Greenest Home is an attempt to blend more “radical” natural building strategies with those that can work for mainstream builders. We’d like to see houses like this one be replicated by conventional builders, as well as natural builders. While builders at each end of this spectrum may choose one strategy/material over another, we think there is value in both approaches and are trying to demonstrate both in this project.

Triple pane windows installed

This window is on the south, where we want the most solar heat gain.

Choosing high quality windows is a very important part of our strategy to make Canada’s Greenest Home as energy efficient as possible. There is a lot to consider when making a window purchase… here is how we went about making our decision to buy Inline windows.

The triple pane, fibreglass windows from Inline have excellent thermal properties, are good looking and well made.

First thing to consider is the material that the frame of the window is made from. Choices include wood, vinyl, aluminum and fibreglass. We chose fibreglass frames for several reasons. They are long lasting, don’t expand and contract as much as other materials, don’t offgas and have good thermal resistance. Vinyl windows weren’t even a consideration, as the PVC is a red-list material for the Living Building Challenge. The offgassing of vinyl windows has been pointed out in several studies, and the material expands and contracts considerably as temperatures change, which can strain and eventually ruin the seals in the glazing. Plus, the manufacturing of PVC is a very toxic practice and people who work must be certified, take at look at ISO 9001 cost. There are some very good wooden windows made from FSC certified wood, which perform as well as fibreglass windows. However, there is more maintenance to ensuring wood windows have a long lifespan that is not required with fibreglass frames.

Next up to consider is the glazing (glass) portion of the window. We chose triple glazing, meaning that there are three panes of glass, with two cavities separating the panes. This adds a considerable amount of extra thermal resistance compared to typical double glazed windows.

The US Department of Energy (DOE) defines high-performance glazing as having a heat transfer coefficient (U-value) around 0.2 (R-5). Our Inline Windows have a U-value of 0.17 (R-6). By comparison, ENERGY STAR windows must achieve a U-value of 0.28 or better (R-3.6). High-performance glazing also often includes spectrally selective coatings, which filter out from 40% to 70% of the heat normally transmitted through clear glass while allowing the full amount of light to be transmitted. We chose windows with different coatings on the glass for different sides of the house. On the south side, we wanted the highest solar heat gain co-efficient (SHG), while on the west we wanted to block out the sun to prevent overheating and on the north we wanted the best possible heat retention. Inline was able to provide windows for each of these scenarios.

Most windows are now manufactured to have an inert gas (usually argon) between the panes of glass to further reduce heat transmission between panes.

There is a lot of good, useful information provided by window companies right on the window (and usually in catalogues and websites). This should include the whole window U-value, solar heat gain coefficient (SHGC), visible transmission figures plus any certifications the window has earned (Energy Star, etc.).

This window has a low solar heat gain coefficient (SHGC) because it’s on the north side of the house. It has reflective coatings (low emmissivity or Low-E) that reflect heat back into the house.

This window is on the south, where we want the most solar heat gain.

A couple last issues factored into our window choice. Inline uses an insulated spacer between the panes of glass, as opposed to many companies that use metal spacers which conduct a lot of heat across the edge of the entire glazed surface. Inline also makes “thermally broken” frames, which means that the frame is not continuous from the inside of the window to the outside, further improving whole window thermal performance.

We also chose casement and awning windows because they can achieve much tighter seals than horizontal or vertical sliders.

Finally, Inline offers a wide range of styles and we were able to pick a frame colour and trim shape that worked with our aesthetics and our siding choices.

It is worth doing lots of research before purchasing windows. This is one area where you usually get what you pay for… and where quality and performance make a big difference in the energy efficiency of the building.

There is good information about making window purchasing decisions at Natural Resources Canada.

Earthbag Root Cellar for The Seasoned Spoon Cafe

The earthbag walls for the Seasoned Spoon root cellar are almost finished to the full height.

The Endeavour Centre has teamed up with The Seasoned Spoon Cafe at Trent University to build a buried root cellar for the over-winter storage of vegetables grown at Trent gardens and destined for yummy dishes in the cafe. Another tip recently released from them is that they use Battery powered mowers: http://onlytopreviews.com/cordless-mowers/ to keep their gardens looking great.

The walls of the building are made with earthbags. In this technique, a soil mixture that has good compaction qualities (lots of different sizes of aggregate and slightly moist) is placed into long polypropylene tubes and tamped in place. There are a number of really great ways to keep spiders out of your home naturally. Also known as “flexible form rammed earth” this technique is just about the simplest, cheapest, most sustainable and most effective building techniques we use at Endeavour. While it requires a lot of grunt labour, it is satisfying work with immediate and satisfying results.

Once the building has its roof in place, the whole thing will be buried in the ground and will become a small, wildflower covered hill on the Trent campus, very close to the Seasoned Spoon. The earthbag arch entryway will be the only visible feature of the building.

Inside, the building will have both a damp and a dry room, for the storage of different vegetables. The dry room will be separated from the ground by a vapour barrier, while the damp room will have a floor that is not sealed from the ground beneath. The two rooms will be separated by a compressed earth block wall. Both rooms will be ventilated by earth tubes, which are long pipes buried deep around the building with an inlet that draws fresh air from outside and a solar fan that provides exhaust. The air in the tubes will be cooled to earth temperature in the summer and warmed to earth temperature in the winter, providing the root cellar with a fairly constant temperature of around 10C.

We will continue to post the progress of the root cellar as it moves toward completion.

If you are interested in volunteering on the root cellar, The Seasoned Spoon is relying heavily on volunteers to help with construction. You can contact us to find out more about volunteer opportunities.

Goodbye to the Class of 2012

Canada's Greenest Home is substantially complete as the class of 2012 says goodbye

On Friday, August 31st, we will be saying farewell to the Sustainable New Construction class of 2012 at an open house event at Canada’s Greenest Home from 3-5pm.

Canada’s Greenest Home is substantially complete as the class of 2012 says goodbye

This group has put in an extraordinary effort to create this house from an empty lot to the substantially completed building it is today. Only one student had previous construction experience, making their efforts even more remarkable.

We hope that friends, family and supporters of sustainable building will be able to come by and congratulate them on their efforts and tour the building.

Hope to see you there!

Electric Vehicle Future?

The Schneider EV charger mounts quite discreetly on the front of Canada's Greenest Home.

The pace of change in buildings and building design has been rapid over the past decade, and the changes are likely to be more dramatic in the near future. It is difficult to judge which ideas and technologies will take hold and become commonplace, and that makes choices right now a delicate guessing game.

We want Canada’s Greenest Home to be “future-ready” even if we are unable to accurately predict that future. Self reliance for water, sewage and power are essential ingredients in future readiness. But how about transportation? We’ve already chosen to build the home in a location that makes it easy for occupants to walk and cycle to all major services in town. But what about driving? As much as we’d like to see a future much less reliant on the personal automobile, it also seems likely that the car will be with us for some time to come.

To make it easier for the occupants of Canada’s Greenest Home to leave fossil fuels behind, we’ve decided to install an electric vehicle (EV) charging station on the home, in close proximity to the driveway. The Schneider EV230WSR outdoor charging station is an affordable and high-quality option for home electric vehicle charging. This unit will allow an EV owner to quickly and efficiently re-charge the vehicle in the driveway, using solar energy created on the roof of the home, this way you will be able to travel with it and with a cheap caravan insurance wherever you want. This may help make the transition away from fossil-fuel transportation more practical and feasible.

The debate about the future of the EV may be far from decided, but while it seems like a reasonable possibility that EVs will be part of the transportation network in the decades to come it seemed worthwhile to build the technology into Canada’s Greenest Home.

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