The next thirty years will be pivotal for the planet and for humanity. By 2050, we will need to have a net zero society in order to avoid the worst consequences of climate change. Our global population is projected to rise to almost 10 billion people, putting added pressure on water systems, wildlife habitat, and ocean life.
The good news is that more people are doing what they can to reduce our environmental impact. Almost all of our clients ask us for a more sustainable home, and it’s a request we’re always delighted to hear. For us, as architects, the process of integrating eco-friendly elements is an important part of creating a home that is uniquely yours.
We often have conversations about sustainability that begin with the clients’ desire to use renewable resources in the construction of their home, which is a laudable sentiment. But there are many ways to build more sustainably, and while some of these elements involve materials, others are based on processes.
When thinking about how to go green with your new home, there are a number of factors to consider:
- Carbon footprint (for the manufacturing of materials, transportation, and ongoing energy use)
- Habitat preservation
- Water use
- Circularity (or reusability)
You also need to think about the entire life cycle of the building: how it’s constructed, how it’s used, and what happens when it’s demolished.
But the two most important ways to build a more sustainable home are easier — and more cost effective — than most people think.
The Two Most Important Ways to Build Green
A 900 square foot home is going to use less energy than a 4,000 square foot home, even if the smaller home’s air tightness and insulation aren’t as good. A smaller home also takes fewer materials to build, and displaces less existing habitat for plants and animals. It will also cost less to build and less to heat, cool, and power.
Insulating the roof is another game changer. While it’s also important to insulate the rest of your home, because heat rises it’s essential to prevent it from dissipating through the roof.
Closed-cell spray foam insulation is the most effective insulator we have right now, with an R-value of 6.5 to 7 per inch of thickness, as compared to a fibreglass batt at R-3.1 to R-3.4. So, if you have a five-inch layer of foam in your roof, that can get you an insulation level of R-35. The other great thing about closed-cell foam is that it seals any gaps left from construction processes and helps provide a barrier against air movement, which reduces heat loss.
There have been concerns in the past about the use of spray foam due to the hydrofluorocarbons (HFCs) that are needed to expand the foam, as HFCs are a powerful greenhouse gas (GHG). As of January 1 2021, however, Canada has banned the use of HFCs in spray foam. The industry has moved to using hydrofluoroolefins (HFOs), which have nearly zero greenhouse gas emissions and do not harm the ozone layer¹.
What does better insulation mean for energy use? While there are many variables that affect the outcome, in a cold climate like ours insulation can mean a difference of thousands of dollars in energy bills every year, and a potential savings of over a hundred tonnes of carbon dioxide over twenty years².
More Ways to Build Green
Build to Last…and to Reuse
Some buildings have to be torn down after only a few decades, others last hundreds of years. If a building lasts longer, it forestalls the need for additional environmental impacts from construction.
There are many ways to ensure longevity for a building, including making it attractive, making it energy efficient, and giving it a sensible layout. Construction quality can also make a big difference; for example, more precise joinery can mean a more air-tight home that saves energy.
Designing homes to withstand more extreme weather events could become more important to their longevity as climate change intensifies. Ottawa experienced two “floods of the century” in 2017 and 2019, and saw highly destructive tornadoes in 2018. While climate experts are hesitant to assign these specific events to climate change, in general they do expect that our area will see more intensive storm patterns over time.
Thinking about the end of life of a building is another way to improve sustainability. If the home is well planned in advance, materials could be selected for reusability, and the design could emphasise modularity so that pieces could be more easily reused.
Reduce the Use of Concrete
In our climate, we typically build basements below the frost line. This helps the building stay in place in spite of the soil upheaval from winter’s freeze-thaw cycles. As a result, we tend to be heavy users of concrete.
While versatile and long-lasting, the cement component of concrete is the source of about 8% of the world’s CO2 emissions³. Only fossil fuels (coal, oil and natural gas) are a greater source of carbon emissions. Concrete manufacturing also requires about 10% of the world’s industrial water use⁴.
Here’s where we come back to the advantages of building a smaller home: inevitably, smaller amounts of construction materials are required. Our m.o.r.e. CLT Cabin project found an innovative way to use less cement.
Incorporate Passive Design
“Passive design” is design that uses the local climate to help heat buildings in winter and cool them in summer. A large component of passive design uses the sun, so that a building collects and stores sunlight in winter and keeps it out in the summer.
In Ottawa’s climate, having more south-facing windows can help keep the building warmer in winter, as more sunlight enters the building (think of a car parked in the sun). In summer, using reflective blinds on these windows will block the sun’s rays and minimise what we call “passive solar gain”.
Deciduous trees and shrubs can be of great help in passive design; large trees can shade a house in summer to help keep it cool, reducing the need for air conditioning. After the leaves fall in autumn, the house gets more sunlight throughout the colder months.
Orienting a building so that it makes use of prevailing winds for cooling can minimise reliance on air conditioning.
Use Energy Efficient Heating and Cooling
Most people in urban Ottawa use natural gas for heating their homes for winter. While natural gas is more eco-friendly than most oil furnaces used before the Energy Crisis of the 1970s, it still comes with a sizable environmental footprint in terms of CO2 emissions. It doesn’t help that the lower prices of natural gas are possible because of the hydraulic fracturing (or “fracking”) process of extraction, which uses a lot of water and can result in a great deal of water pollution.
Switching to more energy efficient heating and cooling not only reduces a home’s carbon footprint, it saves money on energy and helps buffer against rising energy prices in the future.
Heat Pumps
Buying a more energy efficient furnace is a good start, but an even better solution is using a heat pump, which both heats and cools your home. Heat pumps work the same way that your refrigerator does: they basically move heat from one location to another. In winter, heat pumps move warmth from the outdoors into your home, and in summer they do the opposite.
Air source heat pumps use outdoor air as a source of heat (yes, there’s warmth even in freezing outdoor air in winter). Ground source heat pumps (also called “geothermal units”) use a coil buried deep underground, where it doesn’t freeze.
Using heat pumps does require electricity, but overall it’s a much less energy intensive solution.
Wood Stoves and Furnaces
There are also situations in which using a wood stove can be considered environmentally friendly. That’s because wood is part of the existing carbon cycle between the air, plants, animals, and the ocean — what’s known as “green carbon”.
Green carbon is so-called because it doesn’t introduce new carbon dioxide into the atmosphere. Atmospheric carbon dioxide is increasing because of the burning of fossil fuels, which introduce carbon from coal, oil, and gas that has been stored deep underground for millions of years.
If your wood is sourced from sustainably managed wood lots (that don’t reduce wilderness habitat), your home is a modest size, and you’re using an energy efficient stove, there’s a strong case to be made for the sustainability of wood heating.
The Energy Grid and Air Conditioning
As of 2014, Ontario’s energy grid no longer uses coal-fired power plants, and is now 94% GHG-free. It’s primarily based on nuclear energy and hydro, with some natural gas power plants, solar, and wind thrown into the mix.
Because natural gas plants can be fired up and powered down relatively quickly, they’re mostly used in the grid on hot summer days, when everyone switches on their air conditioning. This is a great reason to improve your home’s passive cooling and reduce — or eliminate — electricity use for this purpose.
Triple Glazed Windows
Everyone wants large windows for their new home, but windows are the biggest source of heat loss for buildings.
Insulated walls are typically R-13 to R-23, but a double-glazed window has an R value of just 2 to 3.8. Triple pane windows can be up to R-7, saving a lot of energy and money. For example, an R-7 window saves twice the energy of an R-3.5 window of the same size.
In other words, the larger the windows for your home, the bigger the difference triple-glazing will make to your energy bill and your carbon footprint.
Tankless Water Heaters
Every time you turn on the hot water, you’re likely using fossil fuels to heat that water.
According to Natural Resources Canada, an Energy Star-certified tankless water heater uses 30% less energy than a traditional tank model.
When combined with other tools like low-flow taps and shower heads, and improving our water use habits (more on that below) the energy and cost savings can add up.
Sustainably Harvested (and Recycled) Timber Products
The construction industry uses vast amounts of timber every year: one estimate from the United States in 2006 mentions 6.8 billion cubic feet (187.5 million cubic metres) of solid wood products⁵. Now that we’re aware of how important trees are to reducing atmospheric carbon dioxide, it’s more important than ever to ensure that construction timber is sustainably harvested.
As a rule of thumb, wood products with the Forest Stewardship Council logo on them can be counted on to come from well-managed forests. The FSC is an independent third-party organisation that has certified thousands of North American products, so beware of other programs (run by the timber industry) that are not as stringent.
Wood is often an easy material to recycle. There are several stores and organisations in the Ottawa area that provide access to reclaimed wood from old barns, demolition projects, and felled urban trees.
Using locally-sourced reclaimed timber is a double-win, because your wood has a lower carbon footprint from transportation costs. The fossil fuels used to bring timber from BC to Ontario can outweigh the fact that the wood was grown in a well-managed forest.
It’s also important to remember that the forestry industry uses a lot of fossil fuels while felling, transporting, drying and milling wood before it’s put on a truck and shipped to the end user. While we do have some numbers, it’s difficult to accurately assess the carbon footprint of forestry activities (especially given concerns about the carbon accounting for the Canadian forestry industry as a whole) — let alone calculating the carbon footprint of individual products. You can get an idea of what’s involved from this research paper.
We can only look forward to a time when the exact environmental and social impacts of any product would be easily available to purchasers, similar to the way nutrition information is available on all food packaging.
Reducing Construction Waste
Because building supplies come in different sizes, and few buildings are windowless boxes based on these sizes, there are always “offcuts” in building materials.
There are ways to reduce this waste, however, that go beyond the old saying “measure twice and cut once”. For the m.o.r.e. CLT Cabin project, we designed every piece of the home in 3D, right down to the correct angle of the 10,000+ screw holes. Planning everything down to this level of detail and preparing every piece in advance (so the home could be assembled IKEA-style) minimised waste.
Habitat Preservation
The construction process typically does a lot of damage to the existing landscape. The manoeuvring of construction machinery and on-site storage of materials tears up land well beyond the actual footprint of the house. Most property developers also flatten out any existing rises and falls in the topography so it’s easier to build, and clear-cut existing trees and shrubs if they’re not prevented by law.
Once the existing soil and plant life are damaged, the wildlife tends to leave as well; although some animals may be accidentally killed if they’re too small or too young to flee the site. Often the site is completely denuded and replaced with rolls of turf and very young saplings, even though most buyers want mature trees on their properties.
For cottages and other rural areas, sometimes getting the materials to the site damages the existing landscape. Long-bed trailers are often used for transporting large loads, and they require a lot of room for their turning radius. This can mean cutting trees beside the road.
By sizing loads for smaller trailers, some of this damage can be avoided, as we did for the m.o.r.e. CLT Cabin.
Saving Water
As we have access to plenty of fresh water in the Ottawa area (for now), this issue isn’t on our radar as much as it should be. But climate change could potentially alter our water availability. 2021 saw the driest summer in over 100 years.
Water costs energy, and therefore money to treat and deliver to our homes, as anyone who has ever paid a water bill knows. Water costs in Ottawa have been rising, partly due to the need to overhaul our storm sewer infrastructure, and this increase has been cited as a major reason for the over 20% per-capita decrease in water use since 2005⁶.
There are many ways to save water indoors, including low-flow shower heads and faucets, using a timer for showers, and using an Energy Star-certified dishwasher for dishes (instead of washing by hand as-needed).
Outdoors, water use can depend on your landscaping. Ideally, landscaping should be done with hardy native plants and drought-tolerant plants. If you need to irrigate, use a drip irrigation system and only turn it on at night, when there will be less evaporation and more water will actually reach your plants.
Using Solar Power
While Canada’s lower level of winter sunlight means that it’s unlikely that we’ll be able to power our homes exclusively with solar, it can help us reduce our reliance on other power sources.
The technology for residential solar panels is improving all the time, and because of the way Ontario’s electricity rates are structured, installing solar panels can be very cost effective for rural residents and businesses especially.
For urban residents, solar definitely does pay off long term, but the upfront installation cost can be a barrier for some homeowners in retrofit situations.
The advantage of including solar in a new home build is that installation costs are much lower, because it’s easier to do the electrical work when the building is still incomplete. You can also plan an optimal place (both technically and aesthetically) for the panels much more easily. As you’re building your “forever home”, you’re also more likely to be in residence after the system has paid for itself.
The exact cost of buying a solar panel array will depend on the size of the system, whether or not you buy a battery storage system, and the rebates available at the time. At time of writing, the cost of solar panels is approximately $20,000 to $30,00 for a 7.5 kW system in a retrofit context.
The energy savings should offset the installation costs in about 10 years, and well-installed solar systems can last 25-30 years. As an additional consideration, energy costs typically rise over time.
Building a Greener Home for Today…and for the Future
Building a greener home isn’t about good intentions, it’s about careful planning and, sometimes, balancing conflicting considerations.
A well-designed, energy-efficient home can be as affordable as a conventionally-built one — it’s certainly more affordable for the planet.
References:
- https://www.constructioncanada.net/new-spray-foam-regulations-what-you-should-know/
- https://www.buildwithrise.com/stories/myth-busting-sustainable-homes-cost-more
- https://www.bbc.com/news/science-environment-46455844
- https://www.theguardian.com/cities/2019/feb/25/concrete-the-most-destructive-material-on-earth
- https://www.fs.usda.gov/treesearch/pubs/33882
- https://www.ottawainsights.ca/themes/environment-and-sustainability/other-resources/#:~:text=In%202017%2C%2082%25%20of%20Ottawa,water%20for%20drinking%20since%202009.
