Sustainable Building Program and Courses at The Endeavour Centre

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!

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 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.

There are several portions of Canada’s Greenest Home that do not have straw bale walls. While we believe strongly in the advantages of straw bale walls, we also want to show our students a more mainstream way to achieve high energy efficiency with low environmental impact: double stud framing and dense-packed cellulose insulation.

These sections of the building are framed with 2x4s and are the same depth (14 inches) as the bale wall cavities to give the house the same wall thickness everywhere. Since the dense-packed cellulose has a better R-value than the straw bales, these sections of the building will be very well insulated!

The cellulose insulation we used is made nearby in the Ottawa area from shredded, recycled newspaper and borax. It is a low embodied energy, local material with no real drawbacks environmentally.

Our first inclination was to use wet-sprayed cellulose, as we thought that this would be the best way to fill the cavities and prevent settling. However, the extra thickness of the cavities would have meant that the wet-sprayed cellulose would have had to be applied in several “coats”, adding time and cost to the installation. Our installer, Air Barrier Insulation, suggested dense packing as a better option.

A fine mesh is applied to the interior side of all the studs, which will let air out of the cavities but retain all the cellulose. The cellulose hose is then inserted through a slit in the mesh and the heavy blower (operating at about 60 psi) packs the cavity full of the insulation. The operator continues to pump the cellulose until the blower can no longer force any more into the cavity. At high densities (around 4 pounds per cubic foot) the insulation will not settle.

The blower used by the installer is much more powerful than the typical rental units we’ve used to loose blow cellulose into attic spaces. Having seen this unit in operation, I’d definitely use this type of machine for retrofit applications as well in the future.

The application was quick, relatively tidy and surprisingly less dusty than anticipated. With such an excellent option available to any builder doing conventional stud framing, an affordable and environmentally friendly wall insulation option is an easy choice.

A lot of the attention in a sustainable building goes to the high tech equipment and mechanical systems. But at the heart of a project like Canada’s Greenest Home are some wonderfully simple, low tech and extremely effective structural systems like our clay plastered straw bale walls.

The north wall bales are installed and ready for plastering. The wall studs at 34 inches on centre are visible between the bales.

Installing the straw bale walls on the north side of our building and coating them in clay plaster is a strategy that combines low cost with high performance, and provides a window to a building system that is competitive with current energy-intensive practices but is also feasible in a world with a lot less fossil fuels to expend. These are materials that are locally accessible in most settled regions of the world, and the fact that one can base a very energy efficient home on them gives hope for a future when other materials may be much costlier or no longer available to us.

We installed our bales into a double frame wall system that mimics conventional frame walls, but with the studs placed at 34 inches on centre. In doing so, we create “bays” in the wall that are sized to the length of our straw bales, making bale stacking and plaster preparation very simple and straightforward. Unlike post and beam frames, no notching or cutting of bales is required, nor are heavy beams at the top of the wall. It is a very simple, very cost-effective manner to build a bale wall, and one that many professional bale builders find themselves gravitating toward.

Once the bales are installed, we use a “two-part, one-coat” clay plastering system. A thin coat of a wet clay plaster (1 part clay to 3 parts sand) is rubbed into the surface of the bales to provide a strong key into the straw and an adhesion layer for the bulk coat that follows immediately. This adhesion coat goes on very quickly. The bulk coat is a mix of clay, sand and chopped straw (1 part clay, 1.5 parts sand, 3 parts chopped straw). The more clay plastering we do, the more chopped straw we’ve added to our plasters. The bulk coat resembles a mix between cob and light-clay straw. This coat has enough tensile strength from the chopped straw to be applied to the wall at almost any thickness, from as thin as 1/2 inch to as much as 3 or 4 inches. This allows us to make a straight wall out of a lumpy, bumpy bale wall in a single coat.

We find that this type of clay plastering is a great deal more beginner-friendly than lime or cement based plasters. The clay plaster can be applied by hand, and no trowels or tools are required to make a very straight, even and beautiful wall. To achieve the same results with other plasters would take several more coats and a lot of troweling practice.

This part of the work is also very social, very engaging and a lot of fun. Building a house while up to one’s elbows in mud is a real joy. The fact that we are making an airtight, highly insulated and long-lasting wall system only matters after we wash our hands and look back at the beautiful walls!

High among the priorities for Canada’s Greenest Home is the attempt to make the house a net zero energy building. To reach this goal, we began by designing the most efficient home we possibly could, making energy reduction a major factor in every decision we made during the design and construction process. But this house will use energy, and to offset its consumption we have installed a 5 kilowatt photovoltaic (PV, or “solar panel”) system on the roof. These panels generate electrical power that should, over the course of a year, equal the annual energy consumption of the building.

The PV system installed on the south-facing roof

Sean Flanagan and the excellent team at Flanagan and Sun came and installed the system on our roof this past week. It was exciting to have our first mechanical installation done. PV installations are quite straightforward and fast compared to many mechanical systems. The racking, panels and inverter were all put together in a couple days.

Here in Ontario, the MicroFIT program is run by the provincial government to encourage the addition of small scale renewable energy sources to the overall electricity grid. Homeowners can apply for a MicroFIT contract for systems under 10 kilowatts of peak production power. The government guarantees a sale rate for all such generated electricity for a 20 year contract. The program has been very successful in creating a lot of renewable energy on the grid and helping to reduce costs for system components by making it an attractive investment.

People in Ontario may have heard that the MicroFIT rates were recently reduced from 80 cents per kilowatt hour to 54.9 cents. While this may seem like a disincentive to pursue a MicroFIT contract, in reality the rate reflects the fact that the program’s success has brought down the price of a PV system so dramatically that the rate of return on a system today is similar to that under the higher rate a few years ago. For Canada’s Greenest Home, a MicroFIT contract is an excellent way to meet our net zero targets and create a home which actually pays the owner (around $4,000 annually) while erasing all utility bills. We compare the PV system to building a rental apartment in the house, except that the tenant is completely quiet, always pays up on time and doesn’t add any wear and tear to the house or the owners!

The MicroFIT program in Ontario is one of the best renewable energy incentive programs in the world, and a bright spot in an otherwise dismal landscape for government support of sustainable housing. Seeing the panels on our roof is a point of pride and a look at what all houses could be doing in the future.

If you look beneath many of the most sustainable homes in North America, you’ll often find foam-based insulations. Regardless of the amazing, innovative materials used elsewhere in buildings, we have all been very reliant on foam insulations below grade despite the fact that foam does not meet many of our sustainable building criteria.

Blair holds a handful of lightweight Poraver

We were able to use a remarkable new insulation that works below grade for Canada’s Greenest Home, and it is a real game-changer for our practice going into the future. The insulation is based on a product called Poraver, which are expanded glass balls made from 100% recycled glass here in Ontario. The glass balls share very similar properties with perlite, being a lightweight, mineral-based insulation. However, the Poraver balls are stronger and less dusty than perlite and don’t require the mining of virgin resources, as they are made from recycled glass.

Poraver makes this product largely as a lightweight aggregate for the concrete industry. Mixtures using portland cement and Poraver are not new, but we were not interested in trading the high environmental impacts of foam for the high impacts of cement.

For our project, the binder we used for the Poraver was a mixture of hydrated lime and a material called Metapor. Metapor is “metakaolin,” a kaolin clay that has been fired at high temperatures. This material is a by-product of the manufacture of Poraver. It is an excellent pozzalan, meaning that when mixed with lime and water the pozzolanic reaction is very similar to that of portland cement. Builders have used lime and pozzolans for centuries.

A sample block of Poraver showed us a lightweight, structurally sound insulation

What this means for sustainable builders is that we now have access to a material that has excellent insulative properties (R-value tests are still to come, but we expect results in the R 1.5-2 per inch range), excellent compressive strength (able to support foundation loads) and completely stable below grade (nothing to decompose, or be eaten as with foam and ants).

We used 8 inches of this material under our basement floor. It was easy to mix, easy to install and we were able to walk on the surface 24 hours after pouring.

In the future, we’d like to explore further uses for this material, including foundation walls and above-grade applications as well.

Working with Poraver has been one of the highlights of a project that has included many innovations.

8 inches of Poraver is laid in the basement as insulation below the finished floor