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Air Sealing – The Unseen but Crucial Element

While there are many exciting technologies and materials being used in Canada’s Greenest Home, one of the most important aspects of the home’s energy performance is taking care of air sealing details.

A lot of the heating and cooling energy that is lost from a home is not due to poor insulation, but rather due to air leakage between the inside and the outside. A very well insulated home will not perform well at all if a lot of air can transfer through the building enclosure.

A house is full of seams between different components and materials. At each interface, our team is being thoughtful and careful to ensure that the opportunities for air leakage are minimized. If we do well, we’ll hit the Passive House standard for air tightness of 0.6 AC/H (air changes per hour) at 50Pa (Pascals, the pressure difference between inside and outside during air tightness testing). Our current building code requires a minimum of 3.0 AC/H.

Straw bale walls are well known to have excellent insulative properties, but many straw bale homes are also very leaky at the seams where the plaster meets the ceiling, windows, doors and floors. Through the use of continuous barriers that run behind the plaster at the edges of each bale and tie into barriers at the ceiling, floor and doors and windows, we’ll keep these leaky areas in check.

For example, the bottom plates of our NatureBuilt prefab bale walls feature an air control membrane that is embedded under the plaster skin and extends over the wooden bottom plate. Our air barrier membrane from the foundation ties in behind the barrier from the wall, and the two are taped together at the seam. The baseboard trim will protect this junction from damage.

It’s slow, time-consuming work to ensure that each and every seam is cared for in this way, but it’s a key part of making a home as energy efficient as possible.

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…

The Plywood Dilemma

Among the many perplexing choices facing a sustainable builder, appropriate sourcing of wood ranks high. A lot of wood goes into most buildings, even those that are “straw bale” or feature other alternative building materials.

For the purposes of the Living Building Challenge, and as a responsible builder trying to make good choices, buying lumber that is certified by the Forest Stewardship Council (FSC) is a great way to go when buying lumber and other wood-based products. The FSC certifies forests, mills, production facilities, wholesalers and retailers to ensure that good practices are being used along the entire “chain of custody.”

FSC-certified wood is a great choice, but what about when that choice comes with other considerations? We faced this dilemma when trying to source FSC certified plywood for our subfloor. After much research into plywood manufacturers, we learned that there are no construction-grade plywood mills in Ontario at all anymore, and no plywood mills anywhere in Canada that produced the type of material we needed with an FSC certification.

The only FSC plywood we could find would need to be imported from Oregon (about 4,000 km away), and that plywood still contained phenolic formaldehyde, a product on the Living Building Challenge’s red list of materials to exclude from the building. After more research, we learned that the Living Building Challenge has accepted use of this type of plywood and made exceptions for distance of travel in recognition of the fact that there are no other suppliers for this material.

As an alternative to importing FSC plywood, we looked at decking our floor with a locally milled pine ship-lap. This wood is not FSC certified, but it comes from a family-owned sawmill (Chisholm’s of Roslin) in our local area, a mill that buys all its logs from the local area (within a 100 mile radius of the mill). We’d be breaking a Living Building Challenge directive in using non-FSC wood, but we’d be supporting our local economy, greatly reducing transportation energy and not introducing any traces of formaldehyde into our building. As it turned out, the cost was very similar between the two materials.

Rather than imported plywood, our floor is decked with a locally milled pine 1×8

 

In the end, we decided to use the local wood. It’s a decision we feel good about. But it’s a great example of the different pathways a sustainable builder can take, and the choices that will be faced along the way. My favourite thing about the Living Building Challenge is the way in which it can make a builder reconsider standard practices. Rather than just using a “greener” version of a conventional product, sometimes the better answer is to change practice altogether.

Interestingly, many of the old-timers who visit our site have commented on how this is how they used to deck houses all the time back in the old days… a good reminder that locally-sourced, sustainable building used to be common practice.

There’s More to a Sustainable Building Project than just the Building

Many people think that making a sustainable building is all about choosing the right materials, systems and design features. These are, of course, very important elements.

Our neighbours are supplying us with Bullfrog Power until we have our own renewable energy connection

But there’s more to keeping a project sustainable than this. Take for example the electricity used to build the house before it has a power source of its own. For Canada’s Greenest Home, we made arrangements with our project neighbours (class participant Brian Tighe and his partner Emily Higginson) to use power from their home. And they switched their home to Bullfrog Power www.bullfrogpower.com  so they are helping to guarantee clean, renewable energy on the Ontario grid and ensuring that our project has the least possible impact on the environment, even during the construction stage.

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.

Canada’s Greenest Home Gets Underway

As stated by http://www.exposeyourselfusa.com/video-production/miami-video-production/, students at The Endeavour Centre hit their first milestone on the way to building Canada’s Greenest Home, completing the forming of the foundation footings.

The concrete for the footings will use the highest percentage of blast furnace slag possible, which offsets some of the environmental impacts of cement production. The form boards will be reused as the load bearing walls in the basement.

The footings will support Ontario-made Durisol blocks, an environmentally-friendly Insulated Concrete Form (ICF) with an R-value of 28.

The students have spent four weeks in class, learning sustainable building theory and building science, and researching the products and building techniques that will help their project reach the goal of being Canada’s Greenest Home.

Figuring Out Foundations

There is an expression, “green from the ground up,” which is often used to describe a home that is thoroughly green. However, many homes have a substantial portion that is below the ground, and it is here that many buildings do not carry through on their green promise.

Basement foundations have typically used large amounts of concrete (8-12 inch thick walls that are 8 feet tall, with a 4-6 inch slab floor over the entire footprint of the building), and concrete is a material with a high amount of embodied energy and very high carbon output. In recent years, attempts have been made to make basement foundations more energy efficient, and these attempts have largely relied on foam insulation products. Foam also has very high embodied energy and a whole host of environmental issues, including greenhouse gas emissions, toxic production emissions, and all the negative aspects of petroleum exploration, extraction, production and disposal. Basement foundations made from the combination of these two materials are often thought to be a “necessary evil,” even by green builders.

With Canada’s Greenest Home (as with all our projects), it is our intention to greatly reduce, or potentially eliminate, all concrete and foam use. For most of our projects, we have chosen to build grade-based foundations, and have used materials like earthbags and hempcrete and used carpeting to provide the required structural and insulative values.

Canada’s Greenest Home has many ambitious goals, one of which is on-site treatment of human waste via a composting toilet system. Another is a high degree of solar thermal contribution to the building’s domestic hot water and space heating needs. Both of these elements require storage systems, and the composting toilets require storage below the level of the main floor toilet. Creating basement space for these and all the other mechanical systems makes sense in this scenario. But how to make an energy efficient basement with low embodied energy materials?

We have been considering three different strategies for creating this basement space:

  1. Autoclaved aerated concrete block

    Autoclaved Aerated Concrete blocks (AAC) – This material is also known as cementitious foam. Unlike typical concrete, quartz sand is the only aggregate and the cement is mixed with aluminum powder, causing a chemical reaction that creates hydrogen. These hydrogen bubbles aerate the mix, creating up to 80% void space in the mix. The mixes can be created to have specific densities for particular uses. The wet mix is then steam pressure hardened (autoclaved) for up to 12 hours, giving the mix its structural properties. The combination of structural and insulative properties is highly desirable, as most foundation materials require two separate elements to achieve thermal resistance and structural integrity. AAC blocks are bonded with a purpose made thin mortar, and holes in the blocks are fitted with rebar and filled with concrete for reinforcment. A concrete bond beam is also created at the top of the wall. See Safecrete.

  2. Durisol block

    Durisol Insulated Concrete forms – Most insulated concrete forms (ICFs) are made with foam, and therefore not within our desired range of options. Durisol ICFs, however, are made from cement bonded wood fiber cast into light-weight hollow core blocks that are stacked together, fitted with rebar and filled with concrete. The blocks can contain varying amounts of insulation to create walls of a desired R-value. See Durisol.

  3. First courses of an earthbag foundation

    Earthbag foundation – Rammed earth is a low-impact material, and using polypropylene tubes to act as forms for the rammed earth makes the system quite simple to use. Typically, site soils from the excavation can be used in the tubes, and in the best case scenario will not require any amendment. If the soil is less than ideal, a small amount of cement or slag can be used as a hardener/stabilizer. Because rammed earth has little insulation value, we would need to build a double-wythe wall and fill the middle with insulation.

Each of these three options has strengths and weaknesses. So how can we make the best decision?

First, we think about our goals and priorities. If we’re clear about these, then we know what level of performance we’re asking of each option. We then need to research to find out how each option measures up against each of our goals.

The decision-making process looks something like this:

 

 

* Figures come from the Inventory of Carbon and Energy (ICE) 2.0

Reaching a final decision is a matter of knowing the facts and being able to rank the importance of the criteria. For our foundation, earthbag is the clear winner if we’re only concerned about the lowest environmental impacts and costs. If we’re concerned about energy efficiency, the Durisol is easily the winner. If we want to set a precedent for using an innovative material that has a lot of potential, the AAC blocks win.

In the end, we’ve decided to build with the Durisol. We like that the factory is local, and that the producers use a lot of recycled material in their production process. We like the R-value, and the relatively simple installation process. What we don’t like is the fairly high use of concrete (lower than many other ICFs, but still much more than we usually use). However, we will use the highest possible recycled slag content in our concrete mix and offset some of the environmental impacts.

Earthbag was the leading contender for a long time while designing. However, we are going to be building an earthbag root cellar this summer as well, and felt that the students in the program will get their fill of earthbagging on that project, and would benefit from working with another system (Durisol). We still love earthbag… nothing costs less or has lower impacts, and it’s fun, too!

If AAC were produced locally, there’s a good chance it would be the leading contender. But the closest distributor is in Georgia, and they’ve moved their production facility to Mexico. It’s just too much transportation energy, and the fact that we’d need to add additional insulation sealed the decision.

At Endeavour, we think it’s important to fully explore these questions and options. And equally important to be open about the process, to carefully try and quantify the decision and to reflect honestly at the end of the project about how we feel our goals were or were not met.

We hope you’ll continue to follow the project as we make more decisions! We’ll be starting a dedicated site/blog for the project soon…

 

How to Rate Canada’s Greenest Home

Canada’s Greenest Home Blog #2

One of the key underlying questions about green and sustainable building is: How does one know if a building is really any greener or more sustainable than a typical home?

Quite a number of ratings systems have developed over the past decade to try and help both builders and prospective building owners quantify claims of greenness and sustainability.

At the start of a project like Canada’s Greenest Home, it was important for us to look at all of the various rating systems and select one (or more) that match our goals. As with all things, not all green building rating systems are created equal, nor are many of them even intended to measure the same kinds of performance.

Energy Efficiency

Some programs are designed specifically to rate the energy efficiency of a building and don’t take any other metrics into account. These energy efficiency programs concentrate on higher levels of insulation, better windows, better air control and ventilation systems that recover heat from exhaust air. Lighting and appliance loads are also addressed in most of these programs, with the intent of lowering overall energy usage in the home.

The EnerGuide for New Homes program (from Natural Resources Canada) is now used to establish baseline performance for new residential construction in Canada. EnerGuide provides a score between 1-100, with code approved buildings receiving average scores of 65-72, homes with some efficiency upgrades receiving 73-79 and energy efficient homes scoring above 80. As of January 1, 2012, all new homes in Ontario must be shown to be capable of obtaining an EnerGuide score of 80, so our Canada’s Greenest Home project must provide documentation to the building department from a qualified energy auditor showing that it achieves the minimum of 80. The R-2000 program was a means of achieving an EnerGuide 80, and now that this is the new code minimum the program becomes less relevant. For the Canada’s Greenest Home project, we’re expecting an EnerGuide score in the high 80s or low 90s.

Energy Star for Homes is supported in Canada by Natural Resources Canada. The actual building guidelines and performance targets are very similar to EnerGuide 80 standards. To qualify for Energy Star labeling, a licensed Energy Star builder must build the home, and all the appliances and mechanical systems must be Energy Star rated. We will not be pursuing this certification, though the building will easily meet the requirements.

In the US, the Build America program aims at whole-house energy savings goals of 30% to 50%. We’ve referenced a lot of Build America documents and see a lot of value in the approach, but will not be following this program.

Passive House standards are the most stringent of the energy ratings. In order to be certified as a Passive House, a home must use no more than 15 kWh/m² per year (4746 btu/ft² per year), which can be as much as a 90% reduction from conventional homes. Air infiltration must be at or below 0.6 air changes per hour, also a dramatic reduction from conventional standards. While the term Passive House may suggest homes that don’t have any active mechanical systems, they do require active heating and ventilation systems. However, these systems can be much smaller and more efficient because of the minimal requirements.

We are considering trying to achieve the Passive House standard with Canada’s Greenest Home. A licensed Passive House consultant (Ross Elliott of HomeSol) will be reviewing the plans. We are already including high levels of insulation, an extensive air-tightness strategy and triple-pane windows, which should bring us close to meeting Passive House requirements. We will see what costs and materials will be required to get to Passive House and then decide whether or not we feel there is value in pushing to meet that mark.

Healthy Homes

At Endeavour, we feel there is flawed logic in creating an energy-efficient home that is not a healthy place to live. It is possible to build an entire home without introducing known toxins, and why this isn’t a basic demand from all homeowners is a mystery. Canada’s Greenest Home will use the Standard of Building Biology Testing Methods to assess our attempts to make this home the healthiest environment possible.

Whole Building Systems

More advanced rating systems consider all aspects of the home when assessing its environmental impacts. There are many “whole house” rating systems, some regional and some offered across North America. Most offer a very similar approach. A number of different categories – usually encompassing site/location, energy efficiency, building materials, indoor air quality, water conservation and innovation – are considered, and a number of points are available in each category. Designers and builders achieve points by meeting the criteria in the standard and are awarded certification at the end of the process depending on the number of points attained.

LEED for Homes is the most widely recognized of these programs, and the only one that seems to have achieved mainstream recognition. Having built a LEED Platinum home, Endeavour’s instructors are familiar with this program, and are certain that Canada’s Greenest Home will exceed this standard. However, we are unlikely to pursue LEED certification with this project. While we appreciate the substantial progress made in green building by the adoption of LEED and similar standards (Green Globes, BuiltGreen, GreenHouse, Earth Advantage and many more), our experience with LEED Platinum was that it did not inform or challenge our practices. As builders who have been pursuing high standards of sustainability our entire careers, LEED and similar programs only give us the opportunity to “put a check in the box” for things we already do and leave much of what we do unrecognized. These programs are wonderful for bringing conventional builders onto a greener path and give owners an important means to ensure that a third party is guaranteeing any claims of greenness.

The Living Building Challenge is a sustainable building rating system that we are very excited to engage with for this project. It goes well beyond the other programs and requires a completely different way of thinking about buildings. In each of the seven categories addressed, the Living Building Challenge expects an uncompromising commitment to meeting sustainable goals. It is not a prescriptive or checklist approach, but encourages designers to use the most appropriate regional techniques and materials to meet the philosophical challenge of making buildings that are good citizens of the planet.

Meeting the Living Building Challenge will definitely push our design and build teams to find ways to ensure that our water is collected and treated on site, that our waste is treated on site, that we produce as much power as we use, that we don’t use any fossil fuel combustion, that we provide space to grow food, don’t use any toxic materials and source our materials locally.

It is a challenge we are excited to meet, and we’ll share the whole process on this blog!

Canada’s Greenest Home… The Adventure Begins!

Canada's Greenest Home

Canada’s Greenest Home: What and Why?

Endeavour is excited to announce the Canada’s Greenest Home project, a residential build in Peterborough, Ontario we will undertake with the students in our five-month, Sustainable New Construction certificate program.

We expect the design and building process for this urban infill home will challenge us, our students and the public to think carefully about what it takes to build a home that is safe, comfortable and durable without scarring the earth or endangering the ability of future generations to also live safely and comfortably.

We spent a long time considering the claim we are making: Canada’s Greenest Home. We researched the many homes that have been built in this country in attempts to lower environmental impacts. We found and studied remarkable, thoughtful and well-crafted homes that met net zero energy requirements; that lowered energy consumption by as much as 90% from current norms; that used locally sourced and healthy materials; that helped densify urban neighbourhoods; that collected their own water and treated their own waste; that provided accessibility. What we didn’t find was a home that attempted to do all of these things. A home that does of this, we figured, really would be Canada’s Greenest Home.

This claim is not about competition, not about being the best, breaking records or beating out others. Endeavour is, first and foremost, an educational centre. We want to learn how to reach the highest standards for sustainable home building and to share those standards with our students and anybody else who is interested. We don’t want to be the only ones to build Canada’s Greenest Home. We want to aim as high as possible, and then see that standard surpassed. We will try to outdo ourselves with each project we undertake, and we hope our graduates and others in the construction industry do as well. Ideally, this will be the first of many Greenest Homes.

The best way to live up to high standards is to clearly define them from the outset. In this regard, we’re excited to be using the Living Building Challenge as our standard for Canada’s Greenest Home. Created by the independent International Living Future Institute, it sets the highest standards in existence for sustainable building.

It takes more than claims and computer models to be certified under the Living Building Challenge. Extensive documentation is required to prove the building has met the rigorous standards, and certification is not awarded until performance has been proven over a full year of occupation. We will be proud to join the Eco-Sense home of Ann and Gord Baird in Victoria, BC, as a certified home in Canada.

Throughout the design and construction of Canada’s Greenest Home, we will make every effort to publicly detail the entire process. We are sure to have a steep learning curve, and we want this learning to be a legacy of the project. We hope you will check this blog frequently over the coming months and join us on our path to making Canada’s Greenest Home.


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