Tag Archives: green building

Framing systems for teachers’ union office

Wood framing is a conventional building practice that we use quite frequently at Endeavour. For the teachers’ union project, we are using wood framing for both the floor system and the exterior walls. The walls and floors may not look very different from conventional building, but from a sustainability point of view we’ve made choices that can make a large impact.

First, all the wood framing is certified by the Forest Stewardship Council (FSC), a third party certification organization that helps to ensure that wood products are harvested and processed according to high standards of sustainability. For this project, ensuring FSC certification meant going straight to a FSC certified distributor for our framing lumber and plywood as non of the local lumber yards are FSC certified.

The floor framing uses open web joists from TriForce. These open web joists do not use metal plates, but are finger-jointed and glued, using 2×3 top and bottom chords and 2×2 webs. This uses wood from smaller diameter, fast-growing trees and significantly less wood than solid floor joists, and significantly less glues than wooden I-beams with solid OSB centres. The floor joists are deep enough to allow us to achieve R-46 once they are filled with cellulose insulation.

The 2×6 wall framing is the load bearing exterior wall of the building, and will also be filled with cellulose, adding R-22 to the exterior of our bale walls (more on this hybrid system later), which will be installed to the interior side of the frame.

One of the great advantages of wood framing is the speed of construction and the low cost. When added to the renewability of wood when harvested and processed responsibility, it’s a great combination.

Timber frame for teachers’ union

Timber framing is an important building system for any sustainable builders’ palette of options, and we always try to include a timber framing element in our projects so our students can gain some exposure and experience in this time-honoured way of building.

Our current project features five “bents” or timber frame sections. Four of them hold up the roof over the curved ends of the building, allowing the roof to be straight, square and simple while the walls follow a rounded path. One bent holds up an entry roof section.

The timber frame section from the building plans was reviewed by both our structural engineer (Tim Krahn of Building Alternatives) and our timber framing instructor (Mark Davidson of Whippletree Timber Framing). From Tim’s recommendations on timber sizing and Mark’s expertise at layout and joinery, the initial design was turned into working drawings for the frame.

From Mark’s layout sketches, we went to work on measuring, marking and cutting the joinery on the actual timbers. Mark showed the class the basics of square rule timber framing, introducing us to principles and techniques of using a framing square to achieve the layout.

Each bent consists of three posts supporting two beam sections (joined with a scarf cut) with four knee braces to provide shear support, and we made four identical bents for each corner of the building. Unlike classic timber frame structures, this frame does not support the roof for the whole building but shares the duties with the straight sections of structural wall.

After completing the marking, the joinery was cut using a combination of classic hand tools (saws and chisels) and power tools (circular saw, mortise cutter and drill). In general, the power tools made the big rough cuts and hand tools were used to clean up and refine the cuts to ensure tight, smooth joints. We then drilled the holes into the mortises for the pegs that will hold all the joints on the finished bents.

As the joints in each bent were completed, we arranged sawhorses so that the entire section could be test fit in a horizontal position. Some of the joints needed to be cleaned up a bit in order to assemble the bents, but once the test fit was successful the pieces were numbered and the frames disassembled until the foundation is ready to receive them.

Framing and Bales for the Farm

We do a lot of straw bale work at Endeavour, but it’s such a normal part of what we do that there haven’t been any posts that show us putting in bales for a long time!

Over the past few years, we’ve arrived at a framing system for our bale walls that is very similar to many other professional bale builders. It’s interesting how often a certain approach will become common practice for a number of builders, even without any communication.

This system uses a fairly conventional light wood framing approach, in which we create double stud frames that are 14 inches apart (the width of our bales, on-edge) with the 2×4 studs spaced one bale length apart (for the bales we get here, it’s usually around 28-30 inches on centre). This framing system forms bale “cavities” in which a bale fits snugly. Too tight a fit and the studs will bend from the pressure (especially on 10 foot high walls like here at Circle Organic farm), too loose and there will be a lot of stuffing to do. If the fit is just right, it’s quite easy to get the bales in place, and the gap between the studs is filled with the “puffy” end of the bales. We stuff some extra straw into this space if there’s room, to ensure that there are no spaces without good insulation.

Built this way, we don’t ever have to notch a bale to fit around the framing, and the majority of the stud cavities take a whole bale. For shorter cavities, all the bales for that cavity are made to the same length which simplifies the cutting and retying process. If the math was done right during the planning process, the final bale at the top of each cavity should fit a full bale, tightly.

This system minimizes the amount of bale modification, and relies on very straightforward framing principles. This makes it easy for conventional builders or those with framing experience to frame up a bale wall with ease. Window and door openings are built with the same kind of jack studs and headers as conventional. The top of the wall is a typical doubled 2×4 top plate, so no large diameter beams or complex carpentry is required. The small gap between the top plates is easy to stuff with straw or other insulation.

The exposed sides of each wooden stud are covered with straw that is held in place by zig-zagging bale twine from the end of one bale to the end of the next bale. In this way, the wood is covered prior to plastering without having to rely on housewrap or tar paper.

This framing system uses a similar amount of wood as a conventional single 2×6 stud wall. While we are using double walls, the studs are spaced at least twice the distance apart. It’s a lot of building for a reasonable amount of framing lumber.

Flashings and plaster preparation are handled in a similar way to all other bale installations.

This system has worked well for us over a number of installations, and though we rarely do anything in a standardized way, this framing system is definitely becoming our standard approach.

Stay tuned to find out about the homemade hydraulic lime plaster used on this project!…


First Ever Poraver Foundation

Followers of the Endeavour blog may remember that last year we used an innovative new insulation based on Poraver expanded glass beads as our sub slab insulation for Canada’s Greenest Home. At the time, we were excited to find an insulation that can be reliably used below grade and uses no cement and no foam and offers a reasonable insulation value of around R2 per inch.


As we reported last year, the Poraver product is made from recycled glass that is “aerated,” giving it a cellular structure that is strong but containing enough air pockets to have a good insulation value. As a dry insulation, it can be used in many infill applications, and it is frequently mixed with cement to make lighter weight concrete. The “magic” for us, however, is that a by-product of making the Poraver balls is fired clay, called metakaolin. Metakaolin is a pozzolan, which means that it can be mixed with local hydrated lime to create a hydraulic lime. Hydraulic lime achieves a large percentage of its curing by consuming water, much like cement, meaning a much faster set time, much higher early strength and the ability to use lime in thick applications like a foundation wall. Suddenly, we have a locally produced material that is made from recycled content, and we also use the by-product of the process! Eliminating foam and cement from a foundation with side benefits!

Our positive experience with the material led us to use the Poraver material as the grade beam foundation for the Circle Organics building. With a good compressive strength rating of 0.5 N/mm² (72.5 psi) after seven days, we were keen to build a grade beam that combined structural properties and insulative properties within the same material.

Thanks to our ever-helpful structural engineer, Tim Krahn of Building Alternatives, we were able to build the world’s first expanded glass bead foundation.

We started with a thin, 3-1/2 inch concrete grade beam on top of our rubble trench. The grade beam is below the floor level of the building, and added the bending strength required for the foundation. It is possible that the Poraver could be strong enough without the concrete beam underneath it, but further testing would have been required to justify this, so we went with a thin beam. The concrete was poured in the same formwork we used for the Poraver, simplifying the construction process.

The Poraver grade beam was 16 inches wide (to match the width of the plastered bale walls it supports) and 24 inches tall. It will be partially below grade once the building has been backfilled and graded.

As reinforcement for the Poraver, we bent welded wire mesh (typically used as concrete slab reinforcement) into a square “cage” and laid that in the formwork.

The Poraver was mixed on site in a mortar mixer, using a recipe of 44kg Metapor (metakaolin) to 44kg Hydrated lime. These dry ingredients are mixed with water to make a very wet (cream-consistency) slurry, to which we add 1000l of Poraver of the 2-4mm size. For this project, the engineer suggested adding 5% portland cement to the mix. Hopefully, next time we do this, it can be completely portland cement free.

The mixed material was poured into a form, much like concrete. Once in the form, we spread it and compacted it to ensure it was fully distributed in the forms without any air pockets. The material was hard to the touch in 24 hours, and we removed the forms after 48 hours.

The Poraver material is friable (crushable), making the corners and edges of the foundation vulnerable to chipping when kicked or struck with any force from scrap metal buyers. However, beyond the very edges the material is remarkably resilient. It is able to hold a screw (as long as it isn’t over-torqued). We embedded metal tie straps to anchor the sill plates to the foundation core.

The mixing process was quite quick, as the round balls tumble well in the mixer and get coated in the slurry. Moving the material is easy, as it is very light weight.

This is a material that holds a great deal of potential for future use. It can be mixed on a commercial scale, and potentially formed into blocks or panels, as well as being used for custom pours like this one. This Poraver mix could drastically reduce the amount of styrofoam and concrete used in buildings, replacing it with materials that are much more benign and based on recycled content. We hope to do more work with Poraver in the future.

Poraver foundation

Bart, a towering figure, is dwarfed by his accomplishment: The world’s first Poraver foundation!

Making a Rubble Trench Foundation

Rubble trench foundations offer a means by which to connect a building to frost-free ground in cold climates without resorting to the use of a concrete wall and footing. While rubble trench foundations have a long history, they are not a common practice as most foundations in cold climates incorporate a basement space. Rubble trench foundations cannot be used to make a basement, but they are perfectly suited for buildings with grade-based floors that require a footing below frost depth.

For the Circle Organic building, our rubble trench was 4 feet deep and about 2 feet wide (the width of a backhoe bucket). We used a grade of local crushed stone called 2-4 inch clear stone. This means the fines have been washed out, leaving a rock that is very well draining.

Water that may make it into the trench drains through the stone to a drainage tile at the base of the trench. This drainage pipe slopes around the building and terminates in a “dry sump” where any water can accumulate and percolate into the ground away from the foundation.

The trench is lined with used carpet, which is free for the taking from most carpet installation companies. On the sides of the trench, the carpet prevents wet soil from migrating into the rubble trench and blocking the free-draining rocks. It also provides a small thermal break from the soil.

On the outside of the trench, we also used Roxul Drainboard, a recycled mineral fiber board that is free draining and provides a more significant thermal break. Insulating a rubble trench foundation isn’t necessary, but we are applying solar heat to the ground under the building, and wanted to keep that heat from migrating into the surrounding soil.

The stone in the trench is compacted up to grade level. We then added a layer of 3/4 inch gravel over the trench and over the entire floor area. This stone is easy to level out and compact, and provided a base for the above-grade portion of our foundation as well as the slab floor.

In areas where locally harvested crushed stone is widely available and affordable, this type of foundation makes a lot of sense. It displaces a very large amount of concrete in a very simple and straightforward way. Rubble trench foundations only work in soils where a narrow-ish trench can be dug without the sides caving in. Very sandy or very rocky soils may not be appropriate.

By connecting the building above to frost-free ground below, a rubble trench foundation can often be the lowest embodied energy and most reliable and stable foundation in a sustainable builder’s repertoire. It certainly worked for us at Circle Organics!

Hypar Roof Workshop with George Nez

On July 3rd, the students at Endeavour’s Sustainable New Construction program took part in a day long workshop focused on building hyper-parabolic or “Hypar” roofs.

This type of roofing is much different than any other form of roof. Rather than using dimensional structural material (such as lumber or metal) to create a structural skeleton and then sheathing that skeleton with a waterproof covering (steel sheets, shingles, etc), a hypar roof uses very little material to create the frame and relies instead upon stretching a fabric over the frame to form a hyper parabola (an arch in two perpendicular directions) and coating that fabric with a thin (3/8-inch) layer of latex-modified cement.

Hosted by Henry Weirsma of Fifth Wind Farm and taught by George Nez of Colorado, the class was able to work on all the steps involved in making a hypar roof. We were joined by Tim Krahn of Building Alternatives, who brought his engineering perspective to the proceedings.

We started by examining a cross-gable frame assembled by Henry. While many geometries are possible with hypar roofs, this one has a form that is very compatible with conventional North American housing and roofing styles, and can be used singularly or can be easily combined to roof rectangular or L-shaped buildings. It affords generous gables on all four sides, making the roof space easily habitable.

By stretching fabric and/or mesh across the frame, the hyper parabolic shape is automatically created. This confluence of two arches results in an extremely strong geometry. Many different fabrics and/or meshes can be used. We experimented with fiberglass stucco mesh, polyester bed sheets and landscaping fabric. The fabric/mesh is stretched tightly and stapled along the frame. This material gives the roof its tensile strength.

The compressive strength of the roof comes from pouring a latex-modified cement over the mesh. The latex allows the cement to have a lot of tensile strength, while the cement/sand portion provides the compressive strength. Several layers of this mixture are added to the roof until a layer of 3/8-inch is achieved.

While latex and cement are not highly sustainable materials, the fact that they can be used sparingly to create roofs of high strength (tested to upwards of 50-150 pounds per square foot) and light weight (4 pounds per square foot) while reducing the amount of lumber and other high-cost, high-weight materials make them an exciting option.

George has built hypar roofs all over the world, and showed us photos of examples from Africa, Asia and the USA. He is a passionate advocate for this kind of roof, and he inspired a lively and discussion-filled day.

Hopefully, it won’t be long before Endeavour has a chance to build a full-scale hypar roof on one of our projects!

Did We Build Canada’s Greenest Home?

Exterior of Canada's Greenest Home

Canada’s Greenest Home at 136 1/2 James Street, Peterborough

Canada’s Greenest Home is about to go on the market, and as we switch out of construction mode and into the process of selling the home on its merits we figured this is a good time to reflect on whether or not we’ve met our goals.

Not a Competition

We were initially quite hesitant to brand this project as “Canada’s Greenest.” The claim was not made to be boastful or to dismiss the work of other designers and builders who have made remarkably green homes. The sustainable building community is very “open source” and cooperative, and definitely not competitive. But we were very interested in pushing as many boundaries as possible with this project, to challenge ourselves as designers and builders to make the very best house possible, going beyond what has been done previously.

Our Goals

We had a very well defined set of goals going into this project, and the sum of these goals, we felt, would result in the greenest home in the country. Here is our self-graded report card:

Extremely high energy efficiency

  • The annual heating bill for the home, as determined by energy auditor Ross Elliott of Homesol Building Solutions, will be around $325 annually.
  • The home will have net zero energy use if the occupants have “average” power usage habits, and the photovoltaic panels will provide an income for the homeowners.
  • We achieved a very high degree of air tightness, with the final test showing 0.63 ACH/50 (air changes per hour at a 50 Pascal pressure differential).
  • An Energy Recovery Ventilator (ERV) supplies fresh, filtered air with minimal losses of heat and moisture from the building.
  • A complete energy monitoring system with central touch-screen display will assist the owners in meeting their own energy consumption targets. A smart phone can monitor the system from anywhere in the world.

Extremely high indoor air quality

  • Every finish and surface in the home meets the highest standards for being chemical free and non-toxic. Achieving this level of non-toxicity was a great challenge, and one we’re proud to have met.
  • The air handling system has the best filtration system available, and the owner can control fresh air exchange with simple controls.
  • Occupants with chemical sensitivities should find the home to be a very welcoming environment.

    The interior of Canada's Greenest Home

    Living room with south-facing windows and clay plaster walls

All materials manufactured and sourced as locally as possible

  • There are many green building products available in other markets (Europe, in particular, leads Canada in this way), but we wanted to avoid importing solutions and meet our targets using only materials from within a 250km radius. For all the major components of the building, we were able to achieve this goal. This keeps transportation energy costs and impacts minimal.
  • The market makes achieving this goal very difficult. Outsourcing to less expensive labour markets means that some categories of products are no longer manufactured in Canada, or even in North America.

Very low embodied energy materials

  • We chose materials with the lowest possible harvesting and manufacturing impacts. By choosing materials like straw bale walls from NatureBuilt Walls and recycled cellulose instead of petrochemical foam insulation, we are able to greatly reduce environmental impacts to a fraction of a conventionally-built home’s footprint.

Very low water use, with the potential to be water self-sufficient

  • The rainwater collection and filtration system is designed to allow the homeowner to be water-independent. Connection to the municipal water service gives the homeowner the choice to use rainwater for all or just selected uses.
  • All plumbing fixtures in the home have the lowest possible water usage rates.
  • Composting toilets use 0.1 liters per flush, rather than the industry best 4.0 liters per flush.

No sewage output

  • A complete composting toilet system is one of the most distinguishing features of this home. By eliminating sewage output, the home dramatically lowers its environmental impacts, and by creating useful compost the toilet actually becomes a generative rather than a destructive feature.
  • The foam flush toilets provide the homeowner with a very low maintenance and “normal” toilet experience.
  • The home sends its grey water to the municipal waste water system rather than dealing with it on site. This was our one major area of “compromise,” with regulations, cost and practicality leading us to decide that the small amount of relatively clean water output would go to sewer.

Zero fossil fuel usage

  • An air source heat pump (ASHP) provides heating and cooling with no fossil fuel use.
  • Solar panels provide all of the home’s electricity needs. When the solar power is not available, a contract with Bullfrog Power ensures renewable energy is still meeting the home’s needs.

Very low construction waste

  • By choosing low-waste building materials and carefully re-using, re-purposing, sorting and weighing our leftovers, we were able to send only 852 lbs to landfill, versus 10,000 lbs for an average home of the same size!

Make a Reproducible Home

  • We did not want this home to be a “one-off” specialty home. Any contractor or homeowner can reproduce the results of this home with materials and products that are off-the-shelf.
  • We intentionally did not choose materials or systems that would require skills, sourcing or maintenance that are outside the scope of any builder or homeowner.

Make a Home with “Street Appeal”

  • While aesthetics are a highly personal matter, we wanted to create a home that fit into an existing neighbourhood. The exterior is intended to be attractive without being “showy.”
  • The interior finishes are intended to bring a natural building slant to contemporary design, mixing clean lines and open spaces with natural materials and surfaces. Retraining and retooling is not required to build a home like this.

    Canada's Greenest Home with clay paint on prefab bale wall

    Clay paint on a prefabricated straw bale wall

High educational value

  • Endeavour Centre students, who will hopefully take what they learned into the marketplace and assist with building more homes like this one, built the home.
  • Our construction blog has attempted to document the process of building the home, sharing our experiences, sources and lessons learned.
  • Open houses and post-construction documentation will make this home as open source as possible.

Prove that the market will support green building

  • The home was funded by a private investor as a “spec home,” with no government grants or other incentives.
  • Placing the house on the open market will hopefully show other builders that there is an appetite for homes of this type. We believe that the market is changing and that owners are willing to invest in a home that has very low operating costs and a high degree of resilience, and which makes their health and well being a priority.

Guidelines and Criteria

We used two green building rating programs to help guide us. LEED for Homes offers mainstream builders an excellent tool for measuring their environmental performance and reaching for higher targets. We aimed to exceed the requirements to meet the LEED Platinum standard, and are well on our way to being certified with a points score well in excess of the Platinum requirements.

The Living Building Challenge is the most stringent construction standard we were able to find, and within its guidelines we found plenty of inspiration. In following the Living Building Challenge we definitely stretched our abilities and understanding and elevated our practice. Certification under the LBC can only happen after one year of occupation, so it will be up to the homeowners to continue to meet the challenge.

No Prescribed Solutions

Despite following two great standards, there is no one-size-fits-all solution to building green. We deviated from some recommendations and requirements of both programs in order to pursue solutions we felt were more appropriate for this project.

We Think We Did It!

There is no reward or prize at the end of a process like this beyond the satisfaction of achieving a professional pinnacle and meeting one’s own very high standards. We anxiously await the buyer who will recognize this achievement and work with us to commission the home in a way that ensures it meets its substantial promise.

As designers and builders, we have learned a tremendous amount from this project, and look forward to applying those lessons to future builds. We also look forward to the day when a home like this is the norm, rather than far exceeding the norms. This type of home building on a large scale would have significant and measurable positive impacts on our environment.



Clay Finish Plasters

Natural clay plaster finish at Canada's Greenest Home

Red wall almost finished

Natural clay finish plasters add an unparalleled beauty to any home, and it was exciting to apply these plasters to Canada’s Greenest Home this weekend.

These skim coat plasters can be applied over any wall surface. In this project, we used them over clay base coat plasters and over drywall.

The plasters are mixed on site using widely available and affordable materials. Clay, sand, calcium carbonate, pigment, flour paste and water are mixed together and applied to the wall by trowel in a single, thin coat (~1/8 inch).

Our typical formula is 10 parts clay, 4 parts sifted sand, 1 part calcium carbonate, 1 part flour paste (a natural glue/hardener) and ~3.5 parts water. Natural pigments are added to this mix by weight, based on trial samples made in advance. As with baking, the dry ingredients are mixed together and then added into the water, flour paster and pigment that have been blended.

The clay in this case is Tile 6 Kaolin, from a pottery supply store. We’ve used other kaolins and ball clays with similar results. Calcium carbonate is finely ground limestone, from Omya in Perth, Ontario. Flour paste is cooked by boiling 4 parts water and adding a mixture of 2 parts cold water and 1 part flour and boiling until thick. Our natural pigments come from Kama Pigments.

Helping us with the mixing and application was our good friend Mike Henry, a plasterer with Camel’s Back Construction. His attention to detail helps bring out the best in the clay plaster.

There is nothing like the depth, richness of colour, sound attenuation and warmth of a natural clay finish plaster!

Open House for Canada’s Greenest Home

Join us on Saturday, March 9, 10am – 4pm!

Canada's Greenest Home nears completion

Canada’s Greenest Home nears completion


We have attempted to build the most sustainable home possible, and want to share the results with you! Since April, 2012, the students and faculty of The Endeavour Centre have been working on creating a home that showcases the best in sustainable new construction, and we’re excited to open the doors and show you what we’ve created. Come and see a wide range of sustainable materials and systems, including straw bale walls, clay plasters, Durisol foundation, triple glazed windows, composting toilets, rainwater harvesting and treatment, air source heat pump, ERV, comprehensive energy monitoring, solar hot water, non-toxic finishes and much, much more
Progress Gallery
We hope you’ll come and take a tour at 136 1/2 James Street, Peterborough, Ontario
You can follow the progress of the entire project on our blog

Seasoned Spoon Earthbag Root Cellar Almost Finished

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.

Air Source Heat Pump

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.


Engineering Outside the Box

Please note:
Bruce King is giving two talks in Toronto. For the public presentation, Architecture After Oil, read more here.

For information on the professional seminar, Engineering Outside the Box, continue reading this page…

Engineering Outside the Box, Friday July 27th

Endeavour is pleased and excited to present a seminar with two of the most influential engineers in the realm of natural and sustainable building… Bruce King and John Straube.

The three-part seminar covers everything a building design professional would want to know about working with traditional and emerging natural building materials. The seminar is eligible for OAA credits.

Don’t miss this opportunity to learn from two of the leading figures in natural building!

You can register here.

You can download the seminar outlines here.

ARIDO & OSBBC members receive 40$ off.
Please contact your organization for more info about discounts.

For student rates please contact Endeavour at 705-868-5328 or email us.

Prefab Wall Panels Installed

Upward progress on Canada’s Greenest Home was marked by the arrival this week of our prefabricated straw bale wall panels from NatureBuilt Walls. The class had previously traveled to the NatureBuilt facility to assist in the construction of the panels, and it was great to see them arrive!

The 24 panels for the two stories of the home arrive on one truck


We hired a crane to lift the panels from the delivery truck and onto the foundation. The site of the home this year offered some challenges… between low power lines at the front edge of the property and a long, skinny lot and home design, the usual boom truck used to move the panels was unable to do the lift. Once clear benefit of engaging body corporate maintenance is the fact that your body corporate maintenance will be managed effectively and promptly. So it was Peterborough Crane to the rescue!

The crane sets up and awaits the arrival of the prefab wall panels


The placement of the walls went very quickly and smoothly, and showed why this form of straw bale building is so attractive. Within a couple of hours, we had a full compliment of pre-plastered straw bale walls standing on our foundation. There is no other form of sustainable building that brings such a combination of ease and speed of installation with such a simple, naturally- and locally-based form of construction. We will also be building our north wall in the “conventional” site-built manner, which will offer the class a great comparison of the two methods.

A prefab bale wall panel is lifted into place on the foundation

Soon, the second floor will be ready to receive the next round of prefab walls…

Prefabricated Straw Bale Walls for Canada’s Greenest Home

This week the Endeavour class spent a day at the facilities of NatureBuilt Wall Systems, where we assisted with the construction of some of the Bio-SIP walls that will be used in Canada’s Greenest Home.

The Bio-SIPs are largely identical to the load-bearing straw bale walls that have been used since the first straw bale buildings were constructed in the late 1800s. But rather than building them by stacking bales vertically and plastering in several coats, they are built in a shop space and plastered while lying horizontally. This greatly reduces the amount of labour time involved and ensures walls of consistent strength and size.

We have chosen to use the Bio-SIPs because they meet so many of the criteria we have for Canada’s Greenest Home:

  • Locally harvested materials
  • Renewable materials
  • Reproducible technology
  • High energy efficiency
  • Low embodied energy
  • No off gassing or toxins
  • Affordable

Many straw bale buildings use an extensive wooden framework to create a structure to support a roof so the straw bale and plastering work can be done under protection from weather. The Bio-SIPs use the simplicity and low lumber count of load-bearing walls without the need for excessive wooden framing, capturing the benefits of the load-bearing capacity of straw bale walls.


NatureBuilt takes environmental responsibility seriously, right down to the use of used fryer oil as a release agent in their forms. It was great to be in a workplace where our ethics at Endeavour are so closely matched.

The class got to experience the entire construction process for the panels, including assembling and leveling the wooden frames, selecting and sizing bales, mixing and placing plaster and assembling the bales in the frames. In one short working day, we were able to help build nine of the 24 panels for our project.

The walls will be delivered to our construction site when the first floor framing is ready to receive them.

Our thanks to Ian Weir of NatureBuilt Wall Systems for giving us the opportunity to be part of the production of the Bio-SIPs!

A Finished Durisol block foundation

The Endeavour class has completed the foundation for Canada’s Greenest Home. The crawlspace foundation is made with Durisol blocks. Durisol is an insulated concrete form (ICF) that uses waste wood chips in a cement slurry to form large blocks (in this case, 14 inches wide by 12 inches high by 24 inches long) with an integral Roxul insulation insert. These blocks create a wall with an R-28 insulation value. The main problem that we have when using this material is transporting it. Depending on the location we are going to, we have to be very cautious of the Truck Scales on route because this material tends to be quite a bit heavier than the normal concrete.


The blocks are dry stacked in running bond, and are easily cut with a regular circular saw and blade where required. A grid of rebar is placed in the blocks both horizontally and vertically, and the open channels inside the blocks are poured with concrete (in our case, with the highest slag content possible).

The Durisol system uses waste wood chips, slag content in the cement binder and the Roxul insulation is made with recycled steel slag to create the mineral wool insulation. It’s a higher impact foundation than we would typically use, but because we’re providing a conditioned crawlspace for this building, it was the best solution for this application.

Welcome to Endeavour!

We are very excited to be introducing the Endeavour Centre, a new not-for-profit sustainable learning, building and living centre! While it represents a new beginning in many ways, it’s also the culmination of everything its founding members have been doing as builders and teachers over the past number of years.

We envision Endeavour as an exciting addition to the existing “hubs” of sustainable building activity that dot the globe and provide education, inspiration and support to sustainable builders worldwide. “Hubs” like this don’t spring out of nowhere. Our past roles as creators and instructors at Fleming College’s sustainable building programs has put us at the centre of a growing network of builders, teachers and graduates. With the Endeavour Centre, we hope to intentionally foster this community and help it to grow and develop into something exciting and dynamic.

The heart of Endeavour is its programs. Our full-time New Construction and Renovation programs will offer students an in-depth, hands-on experience in a real-life building project from start to finish. We will be adding a full-time Sustainable Design program to that roster of in-depth, intensive, hands-on learning opportunities.

We’ll be rounding out our full-time offerings with a wide range of exciting workshops that will bring together talented practitioners of sustainable and natural building techniques to share their knowledge in shorter formats. Our workshops will maintain the focus on hands-on, practical learning.

In a world that often seems overfull with “doom and gloom,” we have found that hands-on sustainable building skills are a sure way to overcome malaise and empower people to actively participate in building better communities. The “hub” we envision at Endeavour will bring together people who share a passion for sustainable building and create ties that enable and inspire real change.

We sincerely hope you’ll join us in this Endeavour!



Chris Magwood, Jen Feigin and Diane Csenar

Founding Directors,

The Endeavour Centre