Zero House Project sets ambitious goals

Can we build homes with a zero carbon footprint, that use net zero energy and contain zero toxins?

The Sustainable New Construction class of 2017 is undertaking to answer that question with a resounding “Yes!” And they will be doing it in a completely modular, prefabricated form, at a realistic market cost.

Zero House is a demonstration project being undertaken by Endeavour Centre and Ryerson University’s Department of Architectural Science. The plan originated as SolarBLOCK by ECOstudio, a multi-unit design for urban infill sites. Zero House is a scaled version of a single module of the larger plan – one piece of a potentially larger development.

Zero House is designed to consume no more electricity than it produces in a year, and will use no fossil fuels. The building will sequester more carbon in its plant-based materials (which include wood, straw, mycelium, and recycled paper) than were emitted during material production, positioning it as an important solution to climate change. No materials inside Zero House will contain any questionable chemical content and the building will have an active ventilation system to provide the highest indoor air quality for occupants.

The project will be built in Peterborough in modular components, and then dismantled and rebuilt at the EDITdx Expo for Design, Innovation and Technology in Toronto this fall, where show goers will be able to visit the home, meet the designers and builders and experience Zero House for themselves.

The class of 2017 gathers to start Zero House by making mycelium insulation samples.

The project is being sponsored by many progressive material and system manufacturers, and we will introduce them as their components are placed in the building.

We will keep an ongoing journal of the construction of this project, so keep watching here for updates and to follow our progress!

Fifth Wind Farms wanted to create a building that could reach the energy efficiency requirements of the Passive House standard without resorting to the use of foam, mineral wool or other materials with a high carbon footprint. While straw bale buildings can have excellent energy performance, typical straw bale construction does not meet the Passive House standard without the addition of an extra layer of insulation (see our “Straw-Cell” project for a different take on this idea).

First jumbo bale in place (on a bed of Poraver insulation)

The building owner proposed the use of “jumbo bales,” which are produced from the same local straw and by the same low-carbon machinery, but are of dimensions that greatly increase their thermal performance. While typical straw bales are 14″ x 18″ x 32″, the jumbo bales used for this project measure 32″ x 32″ x 60″! At a nominal R-value of 2.0 per inch, that would give a jumbo bale wall a rating in the range of R-60, more than enough to help the building meet any energy efficiency rating.

However, the jumbo bales provide some issues when it comes to window and door openings… with a wall that thick, window sills and returns are extremely deep, creating not just aesthetic concerns but also concerns about air flow in the deeply recessed bays and the likelihood of condensation forming on the windows in cold weather.

Our solution was to form the window sections at a wall depth of 16″ using double stud framing and hempcrete as the infill insulation. This would keep us on track as far as low carbon footprint is concerned, and the hempcrete would be used to create the tapered window returns to meet the full depth of the bale walls. As a bonus, the hempcrete would completely fill any voids at the ends of the jumbo bales.

One issue with using jumbo bales: they weigh over 500 pounds each! We used a boom truck to install them in the building. With the bales in place and the top plate secured over the bales, we then mixed our hempcrete (you can find our recipe here) and tamped it into the framing and around the jumbo bales. The two materials are very complimentary, with the easily-formed hempcrete able to compensate for the uneven ends of the jumbo bales and creating smooth window returns.

The building is currently being prepared for plastering… more posts to follow soon!

In 2014, Endeavour’s Sustainable New Construction program built a new office building for the Trillium Lakelands Elementary Teachers’ Local in Lindsay, Ontario. The goal was to combine Passive House energy efficiency with low-impact, local and non-toxic materials.

The photo gallery below shows the entire build from start to finish. Click on a photo to view the slide show in full size:

Our office building project for the Trillium Lakelands Teachers’ Union features a straw bale wall system that combines conventional wood stud framing with an interior straw bale wall.

Recently, we finished the exterior side of this wall system. This involved placing dense-packed cellulose insulation in the frame wall, filling the cavity so the insulation is blown tightly against the straw bales. With the cavities insulated, we add approximately R-21.5 to the R-30 of the straw bales. We hire a skip bin in Brisbane contractor for the dense-packed cellulose was Morgan Fiene at New Energy Consulting in Hastings, Ontario (705-313-2004), whose care and concern for doing a thorough job was very refreshing.

We then covered the framing with an insulative wood fibre sheathing. This 1/2 inch wood fibre sheathing has an R-value of 4 per inch, and is made from 100% recycled wood fibre and a non-toxic binder. Made by Western Louisville Fiberboard in Quebec, this product is the cleanest sheathing product we could find. Most exterior wood fibre products use an asphalt emulsion coating, but the SONOclimat product uses a proprietary coating that is water based, non-offgassing and meets stringent environmental standards.

As a means to blend conventional wood framing with straw bale walls to achieve very high insulation values, we have been very pleased with the straw-cell system. It marries low impact materials throughout (earthen plaster, straw bales, cellulose insulation, FSC framing and recycled fibre board) with high insulation value and a straightforward construction process. It’s a great way to marry the more unconventional approaches to sustainable building with mainstream approaches.

Sustainable New Construction 2014 student Ben Bowman set up his camera and took some great sequences of the construction process at our teachers’ union office project.

Here are the two sequences of straw bale installation and earthen plastering. In many ways, these stop motion videos give a better sense of the process than an actual video, plus it makes it all look so fast and easy!

Ben also captured sequences of our earthbag foundation construction and roof craning process:

It’s no secret that we love clay plasters at Endeavour, and the best case scenario is being able to use a clay soil right from the building site. It just so happens that we lucked into this for the teachers’ union office project!

After digging some test holes on the site early in the spring, we discovered that there was a strata in the site soil that was quite clay-rich and appeared to have almost no stone in it (which is very rare in this part of the world). We made some plaster samples from this soil and found that a wide range of recipes seemed to be viable. We left the samples face up into the elements for the whole summer, and one in particular held up really well so we knew we had a workable site plaster.

Our approach to earthen plasters has changed over the years, with the addition of more and more chopped straw over the years so that we have reached a point where we have a very high-straw content in the plaster. We have found that the high-straw recipe allows us to build up the entire thickness of the plaster in a single application. The volume of chopped straw supplies a huge amount of tensile support for the clay, and means that we don’t need to add nearly as much sand as we used to do when our plasters used less chopped straw.

The result is a mix that is very sticky thanks to the high clay content, and has a huge amount of “inner cohesion” that allows it to be applied at almost any thickness (4-5 inches is not unreasonable, if necessary!) with no cracking.

Rather than applying a very runny slip coat via sprayer or dipping the bales, we’ve found that a layer of the same mix minus the straw works well as a “primer”. We apply the primer to the bales, and then follow it immediately with the high-straw “body coat.” It’s sort of a two-part, one-coat system. It’s great to be able to apply the full desired amount of plaster and achieve the final look we want in a single application. Less time, and much less concern for de-lamination between successive coats.

The mix stays moist for a day or two, so it allows a lot of time to get the walls looking how we want, and the mix is very intuitive for those just starting to learn to plaster, while being fast to apply for those with more experience.

Our recipe (by volume) for this plaster is:

• One part high-clay content soil
• One part chopped straw (1/4 – 1 inch)
• 3/4 part rough sand

There’s nothing like playing in the mud and making a viable building at the same time!

Over 20 years of building with straw bales, I have constantly experimented with new ways to integrate bale walls into buildings that are simple, cost-effective and energy/resource efficient. From load bearing to prefab panels to a variety of framing systems, I thought I’d tried them all.

But we were introduced to a new idea by the excellent builders at New Frameworks Natural Building, and we liked the idea so much we decided to try it ourselves.

Their “StrawCell” approach involves building a conventional stud frame wall for the building which acts as the exterior frame and main load bearing element. One immediate advantage is that this system fits into the regular code structure and should not require special engineering or design considerations, which can really ease the permitting process and help to lower costs. The straw bale wall is then built to the inside of the frame wall, with the bales pressed against the framing. The stud wall cavities are then insulated with dense packed cellulose, and sheathed with a permeable board material. Any kind of siding/rainscreen can be created as the final finish on the exterior.

On the interior the bales are very easy to install. The only framing that interrupts the straw is for window and door openings – very similar to the easy installation for load-bearing designs. At the top of the wall there is no beam or framing to notch around, just a plywood plate on the underside of the roof. We tied each bale through to the framing, so the wall was very straight and solid right away.

While the amount of lumber used in this system was initially a red flag for me, an actual calculation showed that we were using no more lumber than any of the other bale wall systems that use a frame of some sort. A conventional frame wall is actually a very effective and efficient way to use lumber, and only some load bearing systems actually use less lumber than this frame wall approach.

One major difference between this system and other straw bale approaches is the lack of exterior plaster. This can be seen as both a plus or a minus. We have been shying away from exterior plaster finishes for clients, especially commercial clients like the teachers’ union. While we love plaster, it is both a high maintenance finish and one that is susceptible to moisture issues unless well detailed, well protected and well maintained. While we definitely have not sworn off using exterior plaster, we are certainly glad to use siding when the client and/or conditions make it appropriate. On the plus side, this system reduces the amount of plastering material and labour required by half (actually, more than half since the interior plastering is always easier). Interior plastering can happen at any time of year, while exterior requires the right weather conditions.

The addition of the cellulose in the exterior wall brings this wall system into the super-insulated category, capable of reaching PassiveHouse standards even in our cold climate (something a single, two-string bale wall cannot do). The cost of the cellulose and siding together are quite similar to the cost of the material and labour for exterior plastering.

All in all, we like this system so far. We’ll continue to report as we finish preparing the walls for plastering and complete the remainder of the system.

TBA, July 2016

Instructors:
Chris Magwood & Jen Feigin

Straw bale walls are unlike any other wall type when it comes to plastering. The unique substrate of undulating straw combined with the many important roles the plaster plays in a straw bale wall system (it is structure, weather-proofing, air sealing and aesthetic finish all in one!) means that plastering straw bale walls is a skill all unto itself.

This workshop will focus on Endeavour’s unique two-part, one-coat system of plastering. Over many years of development, we’ve refined this technique to allow the full depth of plaster to be applied to bale wall at one time. Using a high clay content and a high chopped straw content, this style of plastering combines strength, simplicity and user-friendliness. This system can be used to create the final finish on a wall, or have a final skim coat finish applied over top.

Participants will get to experience materials selection, mixing ratios and equipment, the mixing process and spend lots of guided time applying the plaster to a permanent building.

The workshop will cover clay plasters (using local soils and bagged clay) and clay/lime hybrid plasters.

With this workshop under your belt, you’ll be ready to tackle your own straw bale plastering project!

Entry Requirements:
Open to all

Fee:
Early bird – $295
Regular – $350
Fees include healthy lunches (vegetarian and vegan options available)

Maximum class size: 12

One of the most exciting elements of the Circle Organic farm project is the home-made hydraulic lime plaster we successfully used on the interior and exterior walls of the building. With this new recipe, we are able to make a plaster with locally sourced materials that has a quick hydraulic set and is not affected by erosion or wear due to rain, as can happen with clay plasters.

Natural hydraulic lime (NHL) plasters are made from limestone deposits in which a significant amount of pozzolanic material is naturally occurring in the limestone. These limes come from large deposits in France, and to a lesser degree, Portugal. These limes can be purchased in North America, but are very expensive and it is carbon-intensive to ship heavy materials from overseas. Home made hydraulic lime plasters use the more commonly available hydrated lime available at masonry outlets, to which a pozzolan is added.

We have attempted to mix our own pozzolans with lime in the past, with mixed and mostly disappointing results. But the metakaolin we have sourced from Poraver for our sub-slab insulation and foundations is a very high quality and consistent pozzolan, fired to a high temperature and well-graded for a very reasonable cost.

The recipe for the push-in and the body coat are enshrined on some scrap wood!

As with the Poraver foundation, we mix the metakaolin and lime in even quantities, and use this binder as the basis for the plaster. We first mix up a batch that is 1 part metakaolin, 1 part hydrated lime and 3.5-4 parts sand. This “push-in” mix is made quite thin and wet, and is used to quickly push into the straw bales by hand or trowel because it adheres very well to the straw. We then immediately cover this with a mix that is 5 parts metakaolin, 6 parts hydrated lime, 13 parts sand and 15 parts chopped straw. This coat is applied by hand until it has been built up to the right thickness, and then smoothed out with a magnesium or wood float. This provides a smooth surface that can suffice as a final finish, but also leaves a slightly textured surface in case a final, thin finish coat is desired.

A version of the hydraulic lime plaster with no chopped straw is used to plaster the Durisol block wall

The metakaolin/lime/sand mix can be used as a plaster on smoother substrates without the use of chopped straw. We plastered the Durisol block walls on the project with this type of plaster. Such a mix could be used over a wide variety of wall types, and also used as a final finish coat over the chopped straw mix.

Home made hydraulic lime plaster has several advantages over our typical clay plasters. The hydraulic set happens quite quickly, with the plaster being hard to the touch within 24 hours. This is slower than cement-based plasters, leaving more working time and being more forgiving, but much faster than clay plasters which must dry out, often over several days or weeks. The hydraulic lime plaster is not affected by water once it has set, so the plaster can handle driving rains and repeated wettings without erosion, unlike clay plaster.

While clay plasters are safer (lime can burn skin, lungs and eyes) and more environmentally friendly (lime and metakaolin both require high temperature firing), this home made hydraulic lime uses an industrial by-product (Metapor) that is sourced locally to create a plaster that has all the weather resistance of cement-based plasters without relying on cement.

For a project like the Circle Organic farm building, where conditions are exposed on the exterior and involve lots of veggie washing and other wet activities inside, home made hydraulic lime plaster is an affordable and quite sustainable plaster that will withstand rugged, wet conditions.

The home made hydraulic lime plaster is a very straw-rich mix

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!…

November 18 to 20, 2016
Friday 6-9pm, Sat & Sun 9am to 4.30pm
Endeavour Centre, Peterborough

Workshop Instructors:
Chris Magwood and Jen Feigin

Straw bale building continues to be one of the key sustainable building technologies, where high environmental performance meets code-ready and accessible technology. Straw bales can create beautiful, energy-efficient homes that are light on the environment.

Entry Requirements
Open to all

Fee
Early bird – $400
Regular – $450
Fees include healthy lunch (vegan and vegetarian options available)

Maximum class size: 15

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

Canada’s Greenest Home nears completion

 

December 1st Presentation

On Thursday, December 1st, we are excited to join the Ontario Straw Bale Building Coalition in sponsoring Three Presentations on Straw Bale Construction at Ryerson University, Room ARC 300E, 325 Church Street in Toronto. 7:30 pm

Shi Yi, Wang Li and Tong Yu from the China Academy of Building Research will present on their lab testing program for straw bale walls, and on their involvement in straw bale home building projects in villages around China.

Colin MacDougall from Queen’s University Department of Civil Engineering will present on the numerous testing programs he has conducted on straw bale wall systems and other natural building materials.

Chris Magwood from the Endeavour Centre will present on the state of straw bale construction in Ontario, including homes built by professional bale builders, owner-builders and students.

For those with an interest in straw bale construction, the evening will be a fascinating look at a wide variety of approaches to using straw bale walls and a glimpse at the scientific testing that has made bale buildings acceptable in Canada and China.

For more information, contact us.