Thatch roofs may seem like a romantic and foreign notion in North America, but they are entirely feasible in a wide range of North American climates. No other roofing is annually renewable, carbon-sequestering and non-toxic. A thatch roof may not be for everybody, but it’s worth considering…

This introduction to thatch roof basics is adapted from the book Making Better Buildings by Chris Magwood:

Thatch roof basics

Applications for system

– Roofing for roofs with a minimum pitch of 10:12

– Wall cladding

Basic materials

– Long-stemmed reeds or straw

– Strapping

– Twine or wire to fasten thatch to strapping

How the system works

While it may seem strange for modern builders to think that a bunch of dried grass stems can provide a thoroughly water-resistant and long-lasting roof, thatch roofs have a long and successful history across a wide range of climatic zones. Thatching techniques have been developed worldwide, adapting the basic principle to suit available materials and to work in specific climates. Modern thatched roofs are installed in almost every region of the world, though in relatively small numbers.

The system of thatching used in many wet and/or cold climates involves fastening bundles of long, thick reeds or straw to the roof strapping in successive courses, each overlapping the preceding course. The thatch is laid at a thickness (which can range from 8–20 cm / 3–8 inch) that prevents water from working its way through the layers. Thatched roofs have very steep pitches to aid in this drainage.

Traditional thatch was hand-tied to the roof strapping using twine or rope. Modern thatchers often use screws and wire to provide attachment. Regardless of regional variations in material and technique, the thatch is held in place by securing a horizontal member across the thatch and tying that member back to the strapping through the thatch. The next course of thatch then covers the tie point as the roof is built upward. At the edges of the roof, the thatch is laid at a slight angle to encourage runoff to leave the edge of the roof and to provide a consistent appearance.

Thatching on flat sections of roof is relatively straightforward, but the same cannot be said for ridge, hip and valley sections. These areas take considerable knowledge and experience to execute in a weather-tight and long-lasting manner.

Many modern installations use a fire-resistant (often fiberglass) membrane under the roof strapping to prevent the spread of a fire from inside the building to the roof. Eavestroughs are not typically installed with thatched roofs, making them incompatible with rainwater harvesting.

Tips for successful installation

1. Thatching methods vary widely with the type of thatch material being used and the tradition of thatching used in the region. Ensure that the reed or straw being used is compatible with the climate and the installation technique.
2. Be sure you are able to obtain the material and expertise required to create a thatched roof. It is a rare type of roofing in North America, and must be well researched before deciding to proceed.
3. Plans for a thatched roof must be properly detailed before construction. The uncommon thickness of the roofing, the steep pitch required and the particular details at hips and valleys must be incorporated into the drawings to ensure the roof will work when built.

Dormers, hips and valleys require much more skill than simple gable roofs

Pros and cons of thatch roofs

Environmental impacts

Harvesting — Negligible to Low. Thatch that is harvested regionally will have the lowest environmental impact of any roofing material. The plants that produce useful thatch are annual grasses, making it the only annually renewable roofing. Some reeds that are suitable for thatching do not need to be manually seeded, but occur naturally on marginal lands that are otherwise not suitable for agriculture and aren’t sprayed or treated in any way. Most modern grain plants have been bred to have much shorter, narrower stalks than their genetic ancestors and are not suitable for thatch, but less common grains (spelt, rye, etc) still have stalk lengths and diameters that may work for thatch. Farmed grains may have environmental impacts associated with the use of herbicides and/or pesticides.

Manufacturing — Negligible to Low. Thatch requires little to no processing other than cutting, cleaning and bundling. These processes are done on a small scale and with minimal machinery and fossil fuel input. There are no toxic by-products created.

At the most intensive, a thatch roof will use a small amount of metal wire and screws and a layer of fiberglass matting that has high energy input and some toxic by-products. At the least intensive, round wood strapping and natural fiber twine is used.

Transportation — Negligible to High. Some thatch projects in North America are completed using thatch imported from Europe, because there are no commercial suppliers on this continent. This adds high transportation impacts to an otherwise low-impact roof. Many thatch roofs are made with locally, manually harvested material, keeping impacts very low.

Installation — Negligible. Thatch is largely installed without the use of power tools and does not create any problematic waste or by-products.

Embodied energy & carbon

Waste

Compostable — All reed or straw thatching, natural fiber twine.

Recyclable — Polypropylene twine, metal wire.

Landfill — Fiberglass matt offcuts, if used. Quantities can be negligible to low.

Energy efficiency

Historically, thatched buildings relied on the fairly significant amount of air trapped in the thatch to insulate the roof of the building. However, thatch allows for a lot of air infiltration and would not be considered adequate insulation or airtight enough to meet codes or modern comfort levels on its own. Modern buildings with thatched roofs rely on an insulation layer independent from the roof sheathing.

A thatch roof can have some beneficial effects by reducing summertime warming of the attic space quite significantly. Thatch roofs will also eliminate the issue of condensation on the back side of the roof sheathing as the material will not have the low surface temperatures of more dense sheathing and is able to adsorb and absorb moisture without condensation.

Labor input

Working at heights to install roofing has inherent dangers. Proper setup and safety precautions should always be taken when working on a roof.

Thatch roofing is unique in that, for most North American builders, harvesting the material is likely to be a necessary preliminary step. While suitable materials are widely available, harvesting and preparing them can be a very labor-intensive process, easily requiring more hours than the installation itself. In areas of the world where thatch material is harvested commercially and available for delivery to a job site, the labor input is obviously much lower.

Thatching is the most labor-intensive form of roofing. An experienced thatch crew can move at a speed that approaches that of an experienced cedar shingle crew. Beginners will move a great deal slower, as the process of laying thatch is very particular and must be done accurately and correctly.

Skill level required for the homeowner

Thatching requires a good deal of skill. In European countries, it takes many years of apprenticeship and experience to obtain the title of “Master Thatcher.” Beginners are advised to start with a very small roof, such as a small shed, and to keep roof shapes to simple gables or sheds. Hips and valleys add a lot of complexity to the thatching process, and should be left to those with plenty of experience.

Sourcing/availability

Both the material and the expertise to build a thatch roof can be difficult to source in North America. A few master thatchers practice in the U.S. and they tend to import their thatch material from Europe.

A homeowner wishing to attempt a thatch roof will have to resort to harvesting thatch material locally and learn from books or by taking workshops with experienced thatchers and bringing the skill back home.

Durability

Thatch roofs are surprisingly durable. In northern European climates, they can last for forty to eighty years. Depending on the style of ridge cap used, the ridge may need repair or replacing every ten to twenty years. A thatched roof at the end of its lifespan is not typically replaced; rather new thatch is built over top of the existing thatch.

Code compliance

No building codes in North America address the use of thatch roofs. Proposing a thatch roof will likely require a fair bit of documentation and persuasion, as there are few examples of thatched roofs on which a code official can base an assessment. The historical and modern use of thatch in Europe means that a lot of code-related testing and documentation exists to support it. A building department may be willing to consider a thatch roof with the right amount of documentation and some assurance that the installation is being done properly. The few master thatchers working in North America have been able to have their work approved, as have a small number of owner-builders.

Future development

There is no reason for thatch to be disregarded in North America, as it is a viable, durable roofing option that is remarkably environmentally friendly. As the costs of conventional roofing materials rise with the price of fuel to make them, thatch will start to look better and better. The machinery required to mechanically harvest and bundle thatch is not complicated or expensive, and viable thatch material grows in many places on the continent. There will always be limitations to the use of thatch roofing in urban areas, as fire safety concerns would limit the density of thatched roofs. But there are many locations where thatched roofs are feasible, appropriate and the best possible environmental choice. It will take many dedicated homeowners willing to push the boundaries and create a market in which thatch may start to take the kind of foothold where it creates a viable niche market, similar to cedar shingles.

How does it rate?

Resources for further research

Billett, Michael. The Complete Guide to Living with Thatch. London: Robert Hale, 2003. Print.

Fearn, Jacqueline. Thatch and Thatching. Aylesbury, UK: Shire Publications, 1976. Print.

Sanders, Marjorie, and Roger Angold. Thatches and Thatching: A Handbook for Owners, Thatchers and Conservators. Ramsbury, UK: Crowood, 2012. Print.

The Endeavour Centre is partnering with New Society Publishers to bring natural building enthusiasts a new series of books intended to cover the full spectrum of materials, systems and approaches to natural building.

Called the Sustainable Building Essentials series, the books cover the full range of natural and green building techniques with a focus on sustainable materials and methods and code compliance. Firmly rooted in sound building science and drawing on decades of experience, these large-format, highly-illustrated manuals deliver comprehensive, practical guidance from leading experts using a well-organized step-by-step approach. Whether your interest is foundations, walls, insulation, mechanical systems or final finishes, these unique books present the essential information on each topic.

The first three titles in the series are now available for pre-order from the publisher, with a 20% discount:

Upcoming titles in the series include:

• Essential Straw/Clay Construction
• Essential Green Home Design
• Essential Rainwater Harvesting
• Essential Natural Plasters
• Essential Cordwood Construction
• Essential Composting Toilet Systems
• Essential Green Roofs
• and many more…

We hope that this series helps continue Endeavour’s mission to bring affordable, accessible and accurate sustainable building information to a wide audience!

On April 9, a workshop at Endeavour brought participants together to explore hempcrete insulation materials.

The workshop looked at well-used options for these materials, but also explored some interesting new approaches.

Endeavour has continued to develop the use of homemade hydraulic lime binders as a means to eliminate carbon-heavy cement from our building materials and to create locally-sourced binders for cement replacement. At this point, our homemade hydraulic lime binder is well-tested and we feel it works as well as any of the imported (European) hempcrete binders, at a fraction of the cost and with locally-sourced ingredients.

Hempcrete mix
Our hempcrete binder is composed of 50% hydrated lime (most easily accessible to us is Graymont’s Ivory Finish Lime) and 50% Metapor metakaolin from Poraver (created as a by-product of the company’s expanded glass bead production).

We mix our hempcrete at a ratio of 1 part chopped hemp hurd by weight, with 1.5 parts of the binder by weight. After translating these weights to volume measurements, it was 4 buckets or hemp hurd going into the mixer with 1 bucket of binder (1/2 lime, 1/2 metakaolin).

Weight ratios are converted to bucket measurements: 1/2 bucket of lime, 1/2 bucket of metakaolin, 4 buckets of hemp hurd

The hemp hurd goes into the mortar mixer first and then we sprinkle in the binder and allow it dry mix until the hurd is well coated with binder powder.

A horizontal shaft mortar mixer is used to dry-mix the lime binder and the hemp before water is misted into the mix

Water is then misted (not sprayed) into the mixer until the mix is just moist enough that if we pack it like a snowball in our gloved hands it keeps its shape, but is still fairly fragile (ie, can be broken with a bit of a squeeze). It is important to not over-wet the hempcrete, as this will greatly extend the drying time once the hempcrete has been packed into a wall. If too much water is added, the mix can’t be recovered by adding more dry ingredients as the hemp hurd will quickly absorb excess water and there won’t be any free water for the new dry ingredients. So, add water carefully and gradually!

When packed like a snowball, the hempcrete should just hang together

Hempcrete is placed into formwork on a frame wall, using light hand-pressure to compact the mix just enough to ensure that the binder will stick all the individual pieces of hemp together.

Hempcrete is placed into forms and lightly pressed into place. The forms are leap-frogged up the wall.

Our workshop crew was able to mix and place enough hempcrete to fill a 4-1/4 inch deep wall cavity that was 4-feet wide and 13-feet high in just under 3 hours! That’s over 6 cubic feet of material per hour!

Hempcrete recycling
We have long touted the no-waste benefits of hempcrete. We’ve speculated that even when the insulation is being removed from a building during renovations or demolition, that the hempcrete can be broken up and recycled into a new mix with new binder added. We put that theory to the test at the workshop, as we demolished one of our small sample walls and added the broken up hempcrete into our new mixes at a ratio of 3 parts new hemp to 1 part recycled hempcrete. The resulting mixes were impossible to distinguish from the all-new mixes, and confirmed that hempcrete can easily be re-used!

Hempcrete that had already been mixed into a wall was broken up and added into a new mix… Fully recyclable!

Hempcrete book forthcoming
If you are interested in hempcrete insulation, Endeavour’s Chris Magwood has just finished a book called Essential Hempcrete Construction that will be available in June, 2016. It contains recipes, sourcing, costing, design and installation instructions and will be very valuable to anybody considering a hempcrete project.

New book includes everything you need to know about building with hempcrete

Hemp-clay shows lots of promise!
Hempcrete insulation is almost always done using a lime-based binder. But at the Natural Building Colloquium in Kingston, New Mexico last October, we were doing a hempcrete demonstration right next to a straw/clay demonstration, and we took the opportunity to mix up a block of hemp hurds with a clay binder.

A sample block of hemp-clay showed the potential for this material combination

The success of that demo block led us to try this combination on a slightly larger scale, and we machine mixed the clay and the hemp to fill one tall wall cavity with this hybrid material. Using the same mixing methodology as typical hempcrete, we added the hemp hurd and dry bagged clay to the mixer and allowed it to dry mix, before misting with water. Interestingly, we were able to use half the amount of clay binder compared to lime binder (1/2 bucket of clay to 4 buckets of hemp hurd) and the resulting mix was stickier and easy to form and pack than with the lime, and with the addition of noticeably less water.

The hemp-clay mix has great binding power, and keeps its shape with very little pressure required

The key difference between the two binders is in their manner of setting. Hydraulic lime binders cure chemically, and consume water to change the chemical structure of the mix as it solidifies. Clay binders simply dry out and get hard. So the lime-based versions should be drier and harder sooner. However, the smaller quantity of water required in the clay-hemp mix may mean that drying times end up being similar… we’ll report back when we know.

A close-up of the hemp-clay mix formed into the wall. It keeps its shape within seconds of being placed into the forms

Clay binder with hempcrete offers some advantages over lime-based options, including a significantly lower carbon footprint and none of the caustic nature of lime that can cause skin burns when handling. The clay-based binder creates a mix that is much stickier during installation, which means less packing/tamping to get the material to cohere in the forms. Less water means that it was almost impossible to over-compact the mixture. We will definitely be exploring this option in a serious way!

Having placed 18.5 cubic feet of hempcrete in a few hours, the crew stands in front of their work. The lighter coloured hempcrete is our homemade hydraulic binder, the darker mix is Batichanvre, a binder imported from France.

NEXT HEMPCRETE WORKSHOP: OCTOBER 29, 2016

Maybe the Weirdoes Weren’t So Weird After All

2016 marks the 20^th year since the idea of building houses with straw bales completely transformed my life. Back in 1996, I wanted to build a home for my family that would achieve two seemingly simple goals:

1. The home would make our lives financially sustainable by being affordable to build and having very low operating costs
2. We’d have a smaller impact on the environment than conventional practices

While these were not particularly radical or even new goals, they certainly weren’t ones that we shared with many other people at the time. Our decision to go ahead and build the first code-permitted straw bale home in Ontario was met with many more quizzical looks or outright expressions of derision than interest or congratulations. Almost all of our reasons for building a low-cost, energy-efficient and environmentally friendly home where met with the question, “Why?”

Straw bales almost tripled the code requirements for wall insulation in 1996.

You’re Using R-What?
Then: The notion of insulating a home was well accepted by that time (and even mandated by the building code), but the notion of using anything more than the low code minimum was largely seen as excessive. No insulation was required for basements or under slabs, and air tightness was only being discussed in whispers. The R-2000 program had been around for a while, but even many of its proponents thought the idea of a straw bale wall’s R-40 (or so was the number used at the time) and our plans for R-48 in the roof was kind of overkill. The most receptive audience for the kind of energy efficiency promised by straw bale building was among individual homeowners eager, like us, to greatly reduce or even eliminate heating bills from our monthly overhead, effectively “buying” us a degree of freedom from financial burden.

Now: This is the one area in which conventional building has started to wholeheartedly adopt the strategies of the early green builders. The building code is on a planned pathway to ever-higher levels of insulation and energy efficiency, including targets for improved air tightness. There are numerous voluntary standards to encourage homeowners and builders to exceed code minimum efficiency (such as LEED for Homes and Energy Star), and software programs for modeling energy efficiency. The Passive House standard, nearly unthinkable back in 1996, is gaining traction and showing what’s possible when energy efficiency is taken really seriously. It won’t be long before straw bale walls at R-30 barely meet code requirements, and must already be exceeded to meet the higher standards. It has never been so easy to build a truly energy efficient home.

Recycling old barn timbers was just one strategy to lower the environmental impact.

Environmental Impact from Buildings?
Then: Even less understandable at the time was the urge to build with less of an “ecological footprint.” Even the term itself, which seems to have surfaced in 1992 (coined by Canadian ecologist and University of British Columbia professor William Rees), was unusual at the time, and the notion that choices regarding building materials could have a huge impact on the planet was just starting to be raised as an issue. The fledgling US Green Building Council, formed in 1993, was at the forefront of bringing this issue to light in North America… but nobody was really paying attention. And the idea that these environmental impacts could include climate change due to the high carbon output in the harvesting and production of building materials was nowhere on the public awareness radar.

Now: While there is still a long way to go to remedy the vast impacts that our building materials have on the environment, the problem is at least recognized and seems likely to start to be addressed seriously in the near future. An ever-growing body of data (ICE, EcoInvent, Green Footstep) can help to quantify environmental impacts, embodied energy and, of recent government and citizen concern, carbon footprint. I spent a year of my life writing a book called Making Better Buildings that presents data for a wide range of conventional and green building approaches. It is much easier now than ever before to have an understanding of the impact a building will have on the environment and make informed choices to minimize these impacts. Not many are making these choices, but the groundwork exists and government encouragement to make them seems likely. Advocates for materials like straw bale had a sound argument to make in 1996, and it finally seems to be catching the ear of the wider culture just now.

Home made solar thermal collectors and a cobbled PV system allowed for energy independence.

Renewable Energy?
Then: Our decision to go “off-grid” with our straw bale home wasn’t part of our original plan. But the high cost of hooking up to the grid mixed with a rapidly dwindling budget led us to live our first year or two in the home with no electricity other than a car battery hooked to the water pump. Surprised by the lack of discomfort (ample hot water came from solar collectors and a woodstove jacket), we were able to approach the idea of designing an off-grid electrical system as a way to provide “luxuries” like reading lights, a stereo and laptop computer use. Starting small, the system grew over time to include photovoltaic panels, wind and micro hydro. It was far from the slick systems that are readily available (and less expensive) today, but it met our needs and awakened my interest in examining conventional use of household energy and how high levels of personal comfort could come from vastly reduced consumption. From refrigerators that use cold air in the winter time to augment electric compressors to forays into early forms of LED lighting, the potential for minimizing needs without sacrificing amenities became a passion.

Now: The incredible drop in cost for photovoltaic panels has put renewables on a nearly even footing with fossil fuel energy… Incredible, considering the high levels of subsidies given to fossil fuels versus renewables. Here in Ontario, the MicroFIT program makes it financially prudent to put green energy onto the utility grid, and similar programs exist around North America. Energy storage is a top priority among researchers, with new battery technologies and systems beginning to make it to market. The distinction between being on- and off-grid could get blurry in the next decade as shared distribution of renewable energy on the grid combines with household storage capacity to re-shape household power solutions. This is one area where there are both improvements in the technology and more widespread adoption than twenty years ago. Codes, however, do not address these issues at all.

Non-toxic finishes were difficult to find, and often ended up being home made.

Sick Buildings and Healthy Materials?
Then: The World Health Organization coined the term “sick building syndrome” in 1984, as part of a study that found that over 30% of new or newly renovated buildings were the subject of health complaints by the occupants. The International Institute of Building Biologie and Ecology was formed in 1987. Not many people were listening. But this did not stop academic and lay researchers from questioning the ever-growing number of untested chemicals being combined in our building materials and wondering about the health impacts on building occupants. Those few who were concerned with this issue did not have a wide selection of commercially available products identified as being non-toxic to choose from. Homemade finishes were one important means of having control over what went into a building.

Now: Though an increasing volume and quality of research is showing the negative health effects of toxins in our buildings, this is an area has made very little headway into the mainstream. This despite the fact that we all have a vested interest in living and working in non-toxic buildings.

Small companies began to surface in the early 2000s dedicated to producing building materials free from proven or potentially toxic compounds. While few of these have mainstream distribution channels, it is entirely possible to build an entire house that has no or very little questionable chemical content. Programs like Declare and Cradle-to-Cradle ask manufacturers to fully disclose the ingredients for their building products, and the Living Building Challenge and other programs have chemical red lists to help homeowners and builders avoid potential toxins. There is no recognition of material toxicity in codes.

Low Cost Options
Then: A more regulated residential building sector was just a gleam in regulator’s eyes in 1996. The pathways for owner-builders to pursue innovative projects were less cluttered with requirements, and builders could operate much more informally, outside the scope of prescriptions, taxation and regulation. This meant that several layers of cost did not necessarily have to be borne by a project budget then. Building wasn’t exactly cheap twenty years ago, but the possibilities for building less expensively were there to be pursued.

Now: More regulations that are more strictly enforced have definitely raised building costs over the last two decades. And building material costs have risen at a rate that has exceeded general inflation. Many decades of treating real estate as short-term investment have raised land and building costs, making the cost of projects higher. Development charges, service fees, an increasing reliance on engineering approval and a more formalized scenario for builders have all put upward pressure on costs. It is more difficult than ever to build affordably, so even though the costs of building greener are well within the parameters of conventional costs, those conventional costs are increasingly out of the ability of a typical family to afford. There is no way my family and I could have acted on our 1996 dream if we were in the same position now in 2016. And that is saddening.

Everyone is Coming Down This Path
The forefront of ecological building is still a long way away from mainstream practice. But it’s not nearly as far away as it was twenty years ago; not a result of the leading edge practitioners being less adventurous or pushing less at the boundaries… rather, it’s the mainstream starting to pay attention. It may be a bit like watching a brontosaurus slowly turn its head to acknowledge an annoying bite on its tail, but it is starting to turning around.

Energy efficiency got the construction sector’s attention first. Material impacts on the environment (especially carbon) are increasingly gaining notice, and action on this front is likely in the near future. It won’t be long before occupant health likewise finds active proponents in government and industry, and the presence of toxins in the built environment begins to be treated as seriously as it should.

As I watch the behemoth slowly react, it seems worthwhile to acknowledge that, as with so much social change, the changes start on the fringe with creative thinkers and early adopters acting well outside the mainstream. It turns out that the weirdoes in 1996 were onto something, and that something is looking more and more like it makes “common” sense!

The climate talks in Paris have ended with an unprecedented climate agreement that saw 195 nations sign a commitment to make substantial greenhouse gas emissions. We’ll only know if these commitments are meaningful over the next few years as each country takes steps to meet reduction targets.

One of the difficulties in addressing climate change is getting past the debilitating sense that it is impossible for an individual to make a difference in the face of such vast emission problems. And while it is true that large-scale change needs to be undertaken by government and industry, there is plenty we can do individually to contribute.

Here at Endeavour, we’ve always seen the direct connection between carbon emissions and our built environment. It’s a large part of what’s driven our commitment to high levels of energy efficiency in our building projects. But energy efficiency is only one way to lower emissions when it comes to our homes.

We hear from a lot of people who say, “I’m not able to build myself a new house (or afford a major energy retrofit), so I can’t really make a difference.” It’s true that the cost hurdles to large-scale energy efficiency upgrades are high. Fortunately, there are many other meaningful and affordable ways to have a measurable impact on emissions at home:

1. Don’t use petro-paints. It doesn’t matter if the latex paint you is regular, low-VOC or no-VOC, it’s all petrochemical based and a major source of emissions in its manufacture. The Canadian Paint and Coatings Association estimates that 129.1 million litres of architectural paint were sold in Canada in 2011. The Inventory of Carbon and Emissions (ICE) V.2 estimates that each kilogram of paint manufactured contributes 2.54 kg of CO2 (or equivalent GHGs). That means Canadians contributed 393.5 million kilograms (433,759.5 tons) of CO2 to the atmosphere just by buying petro-paint (this doesn’t include a similar amount of petro-paint for our cars, roads and other industrial uses!).
   Solution: Use natural paints! An amazing array of low-impact paints are readily available, easy to use, durable and beautiful. You can greatly reduce CO2 emissions and avoid bringing toxins into your home in one step. Endeavour works with all kinds of great paints, and you can learn about them here.
2. Consider using wood. There are many places in our homes where wood is an excellent material choice that is often overlooked. From hard- and soft-wood flooring, to wall covering, ceilings, countertops and more, solid wood can be a durable, beautiful option. Most experts in climate changemitigation agree that planting trees is among the best things we can do to reduce atmospheric carbon. It may seem counter-intuitive to take advice to cut down trees, but harvesting mature trees and “locking up” that carbon in our homes for a long time is a good strategy. This is especially true when wood replaces high-carbon materials like plastics, drywall and concrete. Last year, North Americans used 21 billion square feet of drywall, according to the Gypsum Association. Using ICE 2.0 data, that results in 8.58 billion kilograms (9,457,831 tons) of CO2. Wood walls to cover the same surface area would emit 270 million kilograms (297,624 tons) of CO2 in production, and would sequester 540 million kilograms (595,248 tons) of carbon. The net difference? Over 10 million tons of CO2!
   Solution: Plant more trees than we use. Choosing wood that is certified to be sustainably harvested (such as FSC) means that harvested trees are replaced and forests are maintained. And you can go one step better and plant some trees yourself every time you use a wood product.
3. Move to green energy. Renewable energy comes with a very low carbon footprint, and displaces forms of power that are some of the leading contributors to climate change. When most people hear this advice, costly rooftop solar panels are what comes to mind. And if you want to take advantage of Ontario’s MicroFIT program to produce your own green energy, that’s great. But there’s an easier solution…
   Solution: Sign up with Bullfrog Power. Residents of Ontario have a remarkable and simple way to endorse and use green energy: a Bullfrog Power contract. Once you’re signed up with Bullfrog, they will ensure that the amount of power (electricity and natural gas) you use is put onto the grid from renewable sources. It costs just a few dollars a month more, and the transaction is quick and easy. It’s probably the single biggest impact on emissions that you can make, and it just takes a website click or a phone call.
4. Change your energy behaviour. Most of the time, increasing energy efficiency in our homes is a proposition to throw out old appliances and buy new ones. But changing our energy behaviour can make a powerful contribution to reductions, without throwing away anything old and buying anything new. How to make that behavioural change?
   Solution: Install a household energy monitor. A variety of studies, including an influential one here in Ontario, have shown that seeing real-time energy use data on a prominent display in the home can reduce energy use by 5-15%. No changing appliances, light bulbs or anything except our behaviour! You can explore some of the data and some of the excellent energy monitoring options on this blog by Green Building Advisor.
5. Consider the carbon impacts of water. Water is always tied to discussions of climate change, but usually in terms of drought and water shortages. And while this is definitely an important issue, the need to conserve water isn’t just about making sure there’s enough to go around… it’s a carbon issue too. In 2009, the River Network released a report called The Carbon Footprint of Water. Among its findings:
   

   “…the carbon footprint currently associated with moving, treating and heating water in the U.S. is at least 290 million metric tons a year. The CO2 embedded in the nation’s water represents 5% of all U.S. carbon emissions and is equivalent to the emissions of over 62 coal fired power plants.”

   Solution: Invest in water conservation. Dollar for dollar, the changes you can make at home to conserve water will have the best impact on carbon emissions. Putting inexpensive flow restrictors on faucets and showers (or even investing in new ones) is a small investment with real impacts. Changing to an ultra-low flush toilet costs a bit more, but certainly less than new windows or adding insulation. Add a bit of behaviour change to reduce water, maybe switch to rain catchment for lawns and gardens and suddenly you’re using a fraction of a valuable and carbon-heavy resource.

Of course, there are many other ways to lower the carbon footprint associated with your home. Sealing leaks and insulating (with carbon sequestering cellulose and NOT carbon intensive spray foam, fiberglass and rockwool) can reduce long-term emissions. Moving away from gas-powered yard tools is another sure-fire means. Moving to non-fossil fuel heating appliances (biomass or green-electricity fuelled) is expensive but has a great carbon payback.

But don’t give in to climate-change paralysis… The five ideas above are all easy, inexpensive and effective!

The Green Glut
The past 10 years have seen an explosion of building products being marketed to designers and builders as “green.” As the immense impacts buildings have on our planet’s ecosystem started to become clear to the mainstream building industry, marketing departments went crazy to identify just about every kind of product as being “green” in some way or another.

Green?

From my position as someone advising people on green building options, this “glut of green” causes a lot of confusion. If every product is green, what does it mean to really be green?

Real Green Criteria
In order for a product to meet Endeavour’s standard for green, it has to meet several criteria:

• Must have low ecosystem impacts in the harvesting and production of the product. This includes considering both how and where the raw materials are extracted and handled, and what kinds of pollution/emissions happen during the production processes.
• Must have low embodied energy and carbon footprint. This means understanding how much (and what kind) of energy is used to harvest and process the product and the size of the fuel and carbon footprint.
• If applicable, the product must positively impact the long-term energy efficiency and/or performance of the building.
• Should not use and definitely must not emit any dangerous chemicals or off gassing, during manufacturing, use in the home, or at end-of-life.
• Must be durable, and have a reasonable end-of-life strategy (ie, where does it go when it’s taken out of the building).
• Upcycled, recycled and re-purposed materials are preferable.
• Local production is preferable to long-distance shipping.

Meeting Just One Criteria = Not Good Enough
Many building products are sold as “green” if they meet any one of those criteria. Unfortunately, the majority of building products sold as “green” fail (often miserably) when examined against all of these criteria. While the sales team will glowing focus on any glimmering of green in one category, rarely does anything with the green label come close to satisfying a full range of ecological criteria.

Living Products Expo

A Materials Revolution?
The dichotomy between products posing as green and those that are truly green was on display at the recent Living Products Expo, which I attended in Pittsburgh last week. Organized by the International Living Future Institute, the event was billed as “Inspiring a Materials Revolution.” And kudos to the organizers, because this really was the intention of the event.

What Makes Foam Green?
But at one point I found myself in a session that featured several product manufacturers presenting on their new green products. One was a rep from Johns Manville presenting a new polyisocyanurate foam insulation product that does not have added fire retardants (called Energy 3.E). Now this is an interesting achievement, since the flame retardants used in foam insulation are among some of the worst and most persistent chemicals in use on the planet, and up to 15-20% of flame retardant by weight is used in foams. The San Antonio Statement on Brominated and Chlorinated Flame Retardants should be enough to scare all of us away from using any products that use these flame retardants, so to have a foam insulation that eliminates them from its chemistry (without using questionable substitution) can be viewed as a major step, one worthy of the label “green.”

Except that if we put even this insulation to the test of our criteria list, it still fails on many counts. The foam is still a petro-chemical product, and if we don’t like what the oil industry does to the planet (from exploration impacts to drilling sea beds or excavating tar sands to the vast amounts of energy consumed and carbon produced to spills and “toxic events”) then it’s hard to see any foam product as being green. Foam insulation has very high embodied energy and carbon output. It still uses questionable chemistry, has no end-of-life plan and is shipped long distances from a centralized factory. Energy 3.E might be “greener” than other foams, but I don’t think it can really be called green or sustainable. This despite the fact that the product has won all kinds of green awards and has been widely celebrated.

Real Green Insulation
This point was driven home by the next presenter at the same session, this time from Ecovative Design. This company has developed “mushroom foam,” a material that is made from mycelium (mushroom roots) grown amongst agricultural waste fibers. Among its many uses, it can be made into an insulation product with very similar performance qualities as plastic foam. This material satisfies all of the stringent criteria we apply to products in our buildings, and it is naturally flame resistant (interestingly, it turns out that the phosphorus atom the Johns Manville scientists managed to insert into their foam occurs naturally in the mycelium). Unfortunately, Ecovative’s insulation products have not yet reached the mass market, while the foam product has. But the stark difference between the two is a perfect illustration of the difference between being “sort of green” and “really green.”

At the same conference, I gained a more in-depth understanding of two programs that are intended to help builders tell the difference between real green products and those that are just pretending to be green.

Cradle to Cradle Certification
The Cradle to Cradle Products Innovation Institute certifies products on a scale from “bronze” to “gold” based on their satisfaction of a wide-ranging set of criteria. The C2C Products Registry allows one to select a product category (such as Building Supply and Materials) and find products that have met their very high standards. I highly recommend this when searching for truly green products to use in buildings, though the overall number of products is still relatively small.

The Declare Label
Declare is a labelling system introduced by the Int’l Living Future Institute. The Declare label is billed as “a nutrition label for the building industry.” It focuses largely on a transparent declaration of all the ingredients in a product, and where those individual components come from. The Living Building Challenge building certification program has a “red list” of chemicals that it does not allow to be in a building. This label is a means of finding out if a product contains a red list chemical, and what things it contains that may not be desirable even if it is not on the red list. Declare does not consider ecosystem impacts, carbon emissions or other elements of manufacturing, and so is not quite as comprehensive as Cradle To Cradle, but it is still a great development and a useful tool for builders looking at green in a deeper way.

Green Chemistry and Local & Natural
As stated in the Living Product Expo’s desire to spark a “materials revolution,” there is a real move happening toward creating and using building systems that are truly better for the planet. John Warner, a founder of the “green chemistry movement” was a speaker at the Expo, and more and more material developers are starting to use the principles of green chemistry for the built environment. Having presented to the Expo about Endeavour’s methods for prefabricating straw bale wall panels, I found it interesting that the most promising sustainable building systems are relatively low-tech, use waste streams from other processes and are simple to replicate in smaller, regional “micro-factories.” Mushroom foam, straw bale walls, cellulose insulation and so many other effective, truly green materials don’t require major industrial apparatus. To a large degree, this is what makes them truly green. Keeping it simple, local and natural is often the best way to ensure it’s green!

Those of you who follow Endeavour’s work will know that we take indoor environment quality very seriously. Every material that comes into one of our buildings is carefully vetted for its chemical content, and all of our finishes are chosen to be non-toxic. We pride ourselves on making buildings that have the best possible indoor air and water quality for the occupants. This is an aspect of sustainable building that is all too often forgotten, or given minor consideration via the use of low-VOC paints or other small steps.

http://www.carexcanada.ca/en/radon/environmental_estimate/#provincial_tables_and_maps+maps

We have long been aware of the issue of radon gas; the presence of radon gas is an important consideration when trying to create excellent indoor environment quality. Health Canada says: “Radon is a colorless, odorless and tasteless gas formed by the natural breakdown of uranium in soil, rocks and water. It seeps from the ground, and small amounts of radon are always present in the air. If radon gas enters a closed space like a home, it can build to higher concentrations. Radon is radioactive, and potentially carcinogenic if enough of the gas builds up. It is estimated that radon exposure is responsible for about 10 per cent of lung cancer cases in Canada, second only to smoking. Health Canada estimates that 1,900 Canadians died in 2006 from lung cancer resulting from radon exposure.”

Table from http://www.carexcanada.ca/en/radon/environmental_estimate/#provincial_tables_and_maps+maps

When building our Canada’s Greenest Home project, we certainly considered the issue of radon, but after consulting some radon concentration maps and the Peterborough City-County Health Unit’s radon measurements in area homes, we didn’t think that radon would be an issue for this home. Especially considering the heavy duty vapour barrier and careful air sealing we knew we’d be doing, we thought the risk was extremely low.

However, a radon test of the basement – an integral part of getting our LEED Platinum certification – showed that we had very high levels. A long term (3-month) test gave results of 485 Bq/m3 (Becquerel per cubic metre), well above the Canadian acceptable limit of 200 Bq/m3, which itself is above the World Health Organization‘s recommended limit of 100 Bq/m3.

Despite the dangers of long-term exposure to radon gas, it is not so difficult to remedy a high reading, especially in a well-built home with a good basement.

We bought a testing device ($150) and an extraction fan ($250) from Radon Detect. The testing device can give short term (48 hour) and long term readings of radon levels. When we first plugged it in, we had readings in the 370 Bq/m3 range.

The process for lowering the radon level is to drill a hole in the basement slab to extend a 4-inch pipe down into the gravel below. This pipe is then directed out of the building through the basement wall to exhaust outside. We chose to use a fan mounted outdoors, but there are indoor options as well.

Our readings on the meter dropped by over 100 Bq/m3 to 223 Bq/m3 by just installing the 4-inch pipe, prior to hooking the fan up to the power source! Within 48 hours of turning on the fan, the meter was reading just 5 Bq/m3, well below any level of concern.

What is of concern, however, is that all the available information indicated to us that the Peterborough area is considered quite safe from radon, with the Health Unit reporting that only 8% of homes tested higher than 200 Bq/m3. However, the operator of Radon Detect told us that every home he’s ever seen tested in Peterborough has been higher than that, and certainly our readings were very high. Since radon comes from radioactive decomposition of rock and soil, this would indicated that at least our closest neighbours likely have high radon levels, and that high levels may exist in many more homes than we were led to believe. We were double the already-high allowable limit from Health Canada. At least now we own the testing equipment to help others see if they have high levels of radon.

The use of photovoltaics (PV) to generate electricity has been a common element on most of our projects. PV is affordable, easy to install, nearly maintenance free and very reliable. Once again, a PV array has been a key part of the energy strategy for an Endeavour project.

In Ontario, we are able to create grid-tied PV systems, allowing owners to sell some or all of their generated power to the utility company, and also to use grid power when necessary. Grid-tied PV can allow for systems that are sized to meet the owner’s needs, while still ensuring that power is available at all times. For PV to be used off-grid, generating capacity and storage capacity (in the form of batteries) must be sized to meet needs at the worst time of the year (mid-winter, when power needs are high and the amount of available sunlight is low), making the system expensive and likely to over-generate in the summer months.

There are two systems for owners to connect PV systems to the grid in Ontario:

• Under the Micro-FIT program the system owner installs two meters, one for outgoing power being sold to the utility company and one for incoming power to be used in the building. The owner receives a cheque for the full value of power generated (currently 38.4 cents per kilowatt hour), and receives a bill for the full value of power consumed (currently around 11 cents per kilowatt hour). Under Micro-FIT, an owner can generate a financial profit even if production is less than consumption.
• Under the Net Metering program the owner has a single meter, and that meter spins in two directions, “forward” when power is being consumed from the utility grid and “backward” when generation is greater than consumption. Under Net Metering, the power has the same monetary value in either direction. Should production outweigh consumption, a credit will be carried forward on the utility bill (up to a maximum of 11 months). At best, a Net Metering customer can reduce to zero the usage charges on their bill, but can never earn money.

The teachers’ union did not qualify to apply for a Micro-FIT contract, as the restrictions for the program have been growing ever narrower as it becomes more popular. However, with the cost of PV so low now, the economic argument for a Net Metering system is a reasonable one. Combine drastically lowered utility bills with reasonable pay back period and a desire to be part of a renewable energy solution, and you have the grounds for the union’s investment in this 7.5 kilowatt system.

Sean Flanagan of Flanagan and Sun came by this week to turn the system on. With the array and the outdoor connections already made, it was a simple process to turn on the inverter and make sure all the settings were right. Luckily, it was a fairly sunny day and we were able to see about 5 kilowatts of production head out onto the grid when the system became live.

The combination of the PV array and a contract with Bullfrog Power (which we strongly recommend to all our clients) means that 100% of the energy produced and used by this building is from renewable sources.

In 2012, we had a vision of creating a spec-home on an urban infill lot in central Peterborough, a home that would aspire to the very highest standards of sustainable building while also achieving a modern aesthetic that would appeal to a wide range of potential homeowners. We also wanted to build the home in a way that could be easily reproduced by any conventional contractor.

One of our key goals was to ensure that we weren’t just promising improved environmental performance, but that we were achieving measurable results. Having occupied the home for just over a year, we have now had a chance to monitor its performance and calculate a variety of metrics, comparing these to the more conventional homes that share the marketplace. We couldn’t be more pleased with the results, as summarized in the graphic above.

While the performance of the house marks a vast improvement over current practices, perhaps the most remarkable aspect is that this level of performance was not difficult to achieve. Any builder can hit this standard of performance, and do so within the cost range that is currently acceptable in the market. While this project made some more costly investments in PV, rainwater harvesting, composting toilets and solar hot water, a home built to the same level of performance without these “add-ons” would be entirely cost-competitive. And other than the solar income, most of the metrics above would not change if we didn’t invest in these technologies.

Literally anybody can do this type of building, and do it affordably. We intentionally chose to buy off-the-shelf or easily accessible materials and products, from Durisol foundation blocks to prefabricated straw bale wall panels to ready-made clay and lime paints. Everything in this home is available to builders, and every builder already has the skills to create something like this.

This feels like good news when we’re faced with an onslaught of doom-and-gloom news about the environment. Not that this home will save the planet, but when it comes to easily achieved results that have dramatic reductions in impact, the reproduction of homes like this could be a remarkable step in the right direction. Government forecasts show that the US expects about 1,000,000 new home starts per month in 2015, and Canada expects about 190,000. If all of those homes reduced their energy use by the same amount as this project, that would be 89,250,000 gigajoules of energy savings, 189,210,000 liters of water saved, and 156,017,330 gigajoules of saved embodied energy. Those are meaningful numbers (the equivalent of the output of many nuclear generating stations!), and they are immediately achievable.

When we called this project “Canada’s Greenest Home” we were not trying to set an example that would set an untouchable record for green performance. Instead, we were trying to set a standard that would be inspirational in its final performance and entirely reproducible, so that every new home could easily be this green. We feel we’ve achieved this goal. The rest is now up to home owners, home builders and governments to take this example and adopt and improve it.

In 2009, we undertook the first permitted thatch roof in Ontario as part of the Camp Kawartha Environment Centre on the nature preserve grounds at Trent University. This roof sits atop a timber framed entryway for the building and greets all those arriving at this busy public building. The roof is nearing the end of its fifth winter, and a hike along the nature trails near the building gave us a chance to inspect the thatch under a blanket of snow and find that it is still water-tight and holding up very well.

Thatching is a roof system that has ancient origins and is still widely used in a modern context… just not in North America. Only a small handful of buildings on this continent have thatched roofs, and the skill set is extremely limited. This despite the fact that the material for thatching roofs is a widely available invasive reed known as phragmites (or elephant grass). An abundant supply of these reeds grows along many highway medians and ditches.

Thatched roofs exist in a wide range of climates world-wide, with the northern European roofs in countries like Denmark and Germany most closely representing Canadian conditions. In these places, thatching typically lasts 40-70 years, an impressive improvement over the commonly used 25 year asphalt shingles.

The actual process of thatching a roof is a bit more labour intensive than conventional shingling, though experienced crews in Europe move a rate that is not far off conventional practice here. For our project, the manual harvesting and preparation of the reeds was the most labour-intensive aspect. This would be quite easy to mechanize (as has been done elsewhere in the world), which would make thatching a much more viable proposition in this part of the world.

Given that the material for thatching grows annually, for free, along our highways, and that the environmental impact and working lifespan of this type of roof are far better than conventional options, it would be great to see more thatching happening in this part of the world.