DESIGN FOR CLIMATE CHANGE: Architecture for Extreme Weather

Updated: Jun 11


Design for climate change is architecture designed not only to cope with but to perform well during extreme weather. Designing homes to be climate resilient is critical as extreme weather events become more frequent and more severe. Your house was neither designed nor built to handle the climate of the next generation and may be flooded, battered or destroyed as the change in weather patterns that began almost half a century ago continues to accelerate.


The higher risk of damage to your home is one of the impacts of climate change that we as individuals can feel directly. Designing homes to be climate resilient is critical now as extreme weather becomes more frequent and more severe. In your senior years, could you afford the cost of rebuilding some or all of your house if it was compromised? What irreplaceable contents might you lose?


We CAN step up to the challenge of extreme weather. A combination of building strategies in a residential context is key to our adaptive capacity - our ability to adjust our built environment to the climatic events of the coming century. I will show you how to introduce commercial and industrial grade construction to house design by applying my extensive technical experience with different building types, materials, and systems in different Canadian climates, my training in Passive House and Net Zero building design methodology, and my experience with larger buildings that have strict requirements for fire resistance. Learn how atmospheric rivers, cyclones, heat domes, a polar vortex, and weather bombs will impact your home and how your house can be designed and built to keep you safe and comfortable in spite of them.

Climate Impact on Houses

Fire tornado in Carr fire 2018

The first thing that we need to understand here is what "extreme weather" is. When you think about the term 'extreme weather', a tornado might come to mind because it's the easiest to visualize; it's violent, we can see exactly where it is, and it has a distinct shape. However, just as normal weather comes in different flavours, the extremes of other weather do too -- extreme cold, extreme hot, extreme snowfall, torrential rain, violent hail, and vicious wind. We do have a new weather phenomenon: the fire tornado (not to be confused with a fire whirl), of which there are only three instances in recorded history - 2003 Canberra Fire, 2018 Carr Fire, and 2020 Loyalton Fire - but let's focus on weather with which we're familiar but the dangers of which you may not fully realize.

Cold Snaps

Canada understands cold snaps, but as these cold periods become colder and longer, discomfort turns hazardous or fatal. Whether you're in Coal Harbour or Coal River, a week of well-below-seasonal weather can do serious damage. If your furnace or baseboard heating can't keep up when the thermostat is cranked all the way, water pipes in closed spaces can freeze and burst. Condensation will form and ice up around windows, doors, and hidden leaks, and that buildup will gradually rip apart the material and start the growth of toxic black mould as the temperature rises again.

Snowstorms

House partially buried by snow drifts

Most Canadians are no stranger to snow either, but excessive accumulation can be a real problem for a house. First, if the snowfall is greater than what a house is designed to carry, your house's roof structure could fail and begin to sag or even collapse - possibly injuring or killing people inside.

Snow drifting up against the walls potentially causes two problems. First, your doors could be blocked, and you could be literally trapped inside your house by a snowbank. You may chuckle at the idea of digging yourself out, but snowbanks can be actually pretty dense and surprisingly difficult to clear a path through. Second, tall snowdrifts could block the exhaust vents from your kitchen range hood, bathroom fan, clothes dryer, and furnace. Carbon monoxide or other noxious gases could build up inside your house, and you risk asphyxiation.


If you have too much snow and it doesn't blow off or sublimate or melt in time, you will have an increased risk of ice damming on your roof. That ice dam tends to crawl up inside the roof and damage damage to the sheathing and the sheathing membrane. You might've heard something called an ice shield membrane; it's a more robust type of membrane that's actually waterproof.

house covered in ice and icicles

Ice Storms

In addition to being well-acquainted with major snow storms, Eastern Canada is no stranger to ice storms. The ice buildup results either from sleet that accumulates and freezes as night falls, as rain that freezes when it falls, or spray from a nearby body of water. That ice buildup creates dams that trap water on your roof that causes the roofing materials to become saturated, and the subsequent freeze-thaw cycles begin to destroy your roof finish - and possibly the roof structure - in the same way that they create potholes and gradually destroy roads.


Ice is about ten times heavier than snow for a given depth. If ice builds up, it can overload the structure. Roof overhangs - or possibly primary roof structure itself - will sag and possibly collapse.


Hail

Side of house in Calgary showing vinyl siding destroyed by a hailstorm in August 2020

Some areas of the country are experiencing more violent summer storms that produce hail larger than golf balls. The most obvious problem with hail that size is impact damage to the roof finish. Large hail also damages the wall siding and can shatter windows. As with snow, smaller hail can still accumulate on the roof if it doesn't melt quickly enough. If the roof doesn't collapse, the trapped water can saturate the roof materials and lead to moisture-related problems.


Heatwaves

vintage oscillating room fan

Heatwaves are less common here in Canada, but are become a more frequent concern. Obviously it's uncomfortable indoors during a heatwave, especially if you don't have air conditioning. However, the power of an AC system may not be adequate when the outside air is too hot since each system is designed to cool down the air only a certain amount. The system isn't going to be able to keep you comfortable. In fact, if the combination of temperature and humidity get above a certain point - a wet bulb thermometer temperature of 35°C - your body will literally start to cook. I discuss the impact of increasing heatwaves on the livability of your home in this article: How Passive Cooling Keeps Your House Cool During Heatwaves Without the High Cost of Air Conditioning

Deluge

In contrast, extended periods of heavy rain will literally soak your house's roof and walls. Saturated building materials will slowly rot. Excess water migrates to the interior. The dampness allows the growth of harmful black mould. Eventually, the components of the building will rust out or fall apart.


The soil around your house's foundations can also become saturated, and the excess water will either leak into your basement if it overloads the weep tile (a drainage pipe that sits outside your basement) or work its way through the foundations to underneath your floor slab. Water trapped beneath your floor will cause linoleum and sheet flooring to bubble up,

laminate and engineered wood flooring to swell, and some of your tiles to come loose. Carpet will harbour black mould, and the air in your home will be damp and lead to mould in other places as well.

Wind Storms

The seasonal Chinook and related weather fronts in the Prairies are about the closest thing to a dust storm that Canada has typically dealt with, but wind storms are growing stronger. The mountainous terrain of British Columbia is not conducive to the formation of tornadoes, but hotter temperatures in the Southern interior will continue to produce taller, stronger dust devils. The very strongest dust devils are about as powerful as the weakest tornadoes having winds of up to 120 km/h, but even the weakest tornado will rip the finishes off roofs and walls or toss around large debris. Dust is picked up and driven into your home, contaminating every surface.

A tornado in November 2021 takes down a power line and destroys trees at a driving range at UBC
A tornado at UBC takes down a power line

Strong weather fronts regularly attack the coastal areas of both Vancouver Island and the mainland. Cyclones from the Pacific Ocean hit BC as weather bombs and produce long-lasting winds of up to 70 km/h and peak gusts of 150 km/h. These sustained, high winds also tear apart small structures and rip the exterior finishes off of buildings.


climatology map of derechos in North America
Derecho's are generally limited the East US

Another type of wind storm is the derecho - a powerful, linear collection of thunderstorms moving and acting - and destroying - in concert. The linear storm can be as long as the length of Vancouver Island. For example, the June 2012 North American derecho and the August 2020 Midwest derecho caused many billions of dollars in damages. Thankfully, the generally mountainous terrain of BC is not conducive to the formation of a derecho.

Power Outages

Not only do these extreme storms make victims of houses, but they often damage or bring down power generating stations and transmission lines which results in many homes without power. Your house just by being without power and therefore without any heat can lead to severe discomfort or even death. February of 2021 in Texas was a horrific example. Some people froze to death, and some died of carbon monoxide poisoning while trying to warm themselves using camp stoves indoors.

Impact on Homeowners

Higher Insurance Premiums

What about the impact not on the house itself but on the people living in the house? Well, take a look at the increased replacement cost of the house.


Canadian money in various denominations fanned out

Your insurance rates are going to go up. The insurance underwriters recognize the increase in damages. The insurance bureau of Canada has already stated that they're increasing their rates to reflect the upward trend in the number and size of insurance claims. They're revising the tables they use to calculate premiums, and you will see also the insurance policies begin to implement limits or to reduce existing limits on coverage amounts for certain types of natural disasters. That sea change in the insurance world will handicap your insurance coverage later on, so either invest a little more now in either a more intelligent house design or in a more robust host design or, or spend a lot more later on in rebuilding or repair.

Personal Loss

Regardless of the financial cost of replacing the house or a part of it, you must also consider the non-quantifiable potential losses. Irreplaceable contents - heirlooms, artwork, or things that have sentimental value - could be lost or severely damaged. Potentially even pets could be lost or killed, depending on the event. In the worst case, your or a loved one could be injured or killed; perhaps someone is trapped in a fire, is crushed by collapse in high wind, or freezes to death during a power outage in cold weather.

Building Codes Weaknesses

People might assume if their house is built according to the building code, then they will be safe. That's not actually true. The building codes have two weaknesses with respect to extreme weather.

The first weakness is that there is no way to guarantee complete safety, so the building codes must establish an acceptable level of safety to be provided. This level also means that there is an acceptable risk of loss. In other words, since there is no way to guarantee 100% safety, there is no way to guarantee 0% danger. What percentage of danger is considered acceptable? There is no simple answer; the risk allowed depends on how severe the damage or loss would be, the cost of preventing the danger by way of design, and the ability of the building's occupants to protect themselves.


For example, out of all the storms that are expected to occur over the course of a century, only the strongest one would be considered too costly to protect against and too unlikely to happen in your lifetime. That storm would be referred to as a "100 year storm". How does the building code know how bad that storm is - how much rain, how cold, how strong the wind? Past weather records.

And that's where the second weakness of the building code comes in. The climate data upon which the requirements of the building code are based are outdated. They're based on historical weather conditions, which no longer exist. We are already feeling the impact of climate change as historical weather patterns no longer match the climate of the 21st century. For instance, a storm so strong that there was only one like it last century is now happening every few years or so. Let's say every five years. If the old 100-year storm happens every five years from now on, how bad will the new 100-year storm be -- the storm so bad that it happens only once in the coming century? Climatic events that would not previously have been anticipated - because they never happened in recorded history - will have to become the basis for design moving forward.

Consequently, what was previously an acceptable risk is now no longer acceptable. Current building codes are behind; we don't have historical data yet upon which to derive new requirements. Bringing the building code requirements up to speed with current weather patterns would require governments to commit to the climate crisis more than to political acceptance. The future climate scenario will undoubtedly differ from today's climate, but by now much? The effects of climate change that have occurred are not entirely understood, and the potential impact yet to come is pure speculation. Projecting future weather normals would be purely projection. As necessary as climate projections might be, the political ramifications of implementing those as building codes is fraught with debate - political suicide for any government - and as a result building codes climatic design parameters are out of date.

New Hazards

Pests


Despite stronger winter storms, winters overall are becoming milder. The migration of invasive species - for example pine beetle and termites - is a result of winter temperatures no longer being low enough to kill off or keep away an infestation. We will continue to see more immigration of insects that damage house construction.


Wildfires

House on forested mountaintop on fire

Wildfires are also an increasing hazard for a combination of reasons, but the unavoidable and indisputable fact is that longer periods of hotter weather dry out the vegetation - trees, bushes, shrubs, and grass - more, and that dried-out vegetation is far more likely to catch fire due to lightning, sparks from trains, stray embers from campfires or any other open flame. When a wildfire does occur, the burning is more ferocious. The embers themselves travel as much as two kilometres ahead of the fire, or even further with favorable wind conditions. That's how larger fires have been making their way well into the suburbs. Even if you're nowhere near a wildfire, the smoke itself can travel halfway around the world and enter through your air intake and inside your house.

aerial photo showing post-storm flooding of Merritt in 2021
Flooding in Merritt 2021

Floods

Flooding has begun to occur in areas which previously had no flooding concerns. Flooding is not limited to low lying areas, or to the water's edge of a riverbank known to periodically flood. The municipal sewage system could back up into homes or contaminate the drinking water supply - as has been the case in the Abbotsford water supply in late November 2021. Flooding will damage your home's structure, interior and exterior finishes, and contents. In the worst case, a house can be washed away. See below 2021 flood damages - China, Canada, and Germany.



Storm surge

If you happen to be near the coast on a waterfront property, the greatest damage that comes from a storm surge from hurricanes or any similar storm is actually the water. Rising because it's being pushed in by extreme winds and that water level rises far more than the tide and that can carry with it anything that floats - loose furniture, trees, cars, boats. The lasting saltwater damage or threat of corrosion or contamination by anything the water might've gotten into such as the sewers.



Design Strategies


After you compile all the impending weather hazards, you may want to tune out the doom-and-gloom, hope for a long stretch of good years, and deal with the damages when they happen. After all, worrying does nobody any good, right? The cost of reconstruction will be far more than the original cost of construction, and you may already be retired when the damage strikes.


Your home is a huge investment of money, time, and love. The least expensive approach to protecting that investment is to use the appropriate design strategies that will save your house from the majority of events that would otherwise destroy it. Continue reading to learn what those strategies are, how they work, and consider how they could be implemented in your new house design.

Location

The site that you select on which to build - the property you buy - will affect the risks you'll face. A heavily-treed area is less subject to extremely high winds and tornadoes, but the risk of wildfire is much greater. A spot near the ocean is less subject to temperature extremes and forest fires. However, storms from the ocean are stronger, and high waves resulting from sea level rise, storm surge, or tsunami will wash out a site that is too low. A property that sits in the middle of a city is generally more protected from the worst winds and seaborne storms, but the heat island effect worsens the impact of a heatwave. Building at the foot or on the side of a mountain may keep you safe from flooding and perhaps heatwaves, but you will need to design for more snow, ice, and higher winds.


Regardless of what location you choose, there are risks. Likewise, regardless of which extreme weather risks you face, there are techniques which we can use to mitigate them. We borrow traditional strategies from different parts of the world and add new concepts learned through the past century of building science.

Snow - alpine regions of Germany and France

Ice - Norway, Eastern Canada

High wind - Florida

Tornadoes - central USA

Deluge - Southeast Asia

Heatwaves - Middle East and North Africa

Wildfire - Australia

Termites - Southern USA

Hail -


Areas which are subject to tornadoes using their techniques for addressing high wind damage or hurricane prone areas where it's not only high wind, but when wind driven rain and storms are. And of course areas which like in Southeast Asia have traditionally had monsoon flooding.

Building Form

So, what are those design strategies then? What can we take in, in summary for? Well, the first is really the building form rather than getting into tips, tricks and all sorts of fancy stuff. Just a shape of the building itself. A low compact building is always going to be the most secure, the least vulnerable.


For instance, if you have a low sloped roof, that's better for. resisting wind damage. Um, it's better. It's it catches fire less easily. However with a low slope roof, there is the drawback that it's more likely to develop wind, more likely to develop excess snow load. Of course, there's a, another trick to deal with that.

The cantilever. Are better at keeping out the hot sun during the summer and helping to avoid overheating of the interior, but you have to execute them properly. You have to put them in the right places, the right way to avoid that extra, win, that extra roof overhang turning into a sale, essentially that high winds will grab and pick up and possibly lift the structure off of through walls.

A simple roof with fewer valleys, ridges, dormers, and skylights, reduces the chance of embers from a nearby or wildfire collecting and starting a fire.

Similarly, a simple roof presents less opportunity for excessive snow build-up and less likelihood of ice damming and its related water problems.

Some houses in flood-prone areas are designed with a raised living level that is secure from flooding. The lower level is used for something less impacted by a flood and is designed to be less damaged by flooding or more easily repairable after a flood.

Core Material

The core materials of the building structure itself are typically lumber framing or occasionally concrete. You may want to consider mass timber products such as cross-laminated timber, referred to also as CLT. It is more robust. It is more resistant to fire it. It chars. I have an article on that more, more robust than typical lumber framing

. Also, I might want to consider mineral fiber insulation as it is. Is it is resistant to fire and it's more resistant to mold.

So extreme wetting events, heavy, heavy rainfall. You're not going to have to worry all of a sudden, about, high mold growth, and it does dry out fairly well.

Finish Materials

Now the finished materials on the outside of the building in addressing the risk of wildfire a non-combustible finished. For both your roof and for your siding decreases the flammability.

A metal roof is not only better at resisting catching fire, but it's also a better at shedding snow and water. If you use a thick metal type. Or even if you use slate, tile, roofing, they have the best wind resistance and high resistance to hail also to damage by hail. In general, you want to go with non porous, finishes both on your wall and on your roof to avoid rain saturated.

Rain can cause a problem as well for some roof materials. Wood shakes or asphalt shingles can become saturated.

Either the material falling apart, because it's just so soaked or because of mold that starts to grow or because of freeze thaw. If it happens to be a, an ice or slush,

In my article The Fireproof House - How to Design a Fire Resistant House to Protect Your Home from Wildfire


Building Features

Building features that you may want to consider are hurricane rated doors to help keep out the wind and the wind blown rain through the door opening.

Since it's only fully secured at the hinge side, the seal on the other three sides of the door. You want that to be really strict? Storm shutters, um, actually are really good at resisting hail impact. They're good at preventing damage by fire. they're they're great for resisting debris. That's picked up and blown around by really strong winds.

And even inside the, even just the glass itself and the windows, if you're using impact resistant, laminated glass in your windows, they're able to stand up to when someone blow debris themselves, even if you don't have shutters, but of course, shutters are they're stronger and they offer more protection also against fire.


Interiors

In the event of a flood, wall-to-wall carpeting is not going to be a good flooring option. Laminate flooring will also be destroyed, and engineered wood flooring will be considerably damaged. Solid wood flooring will better withstand the wetting as long as it is dried out as quickly as possible to reduce mould growth. Tile flooring and exposed concrete floors are of course the best material to resist flooding events.

Solid wood cabinetry in general is better at resisting water damage. The typical fibreboard or MDF will puff up and be destroyed if it gets wet even just once.

Building Envelope

Airtightness of the building envelope, meaning the walls, roofs floors -, the more air tight you can make your building, the better you're able to keep heat in and cold out when it's extremely cold when the power goes out. Extra insulation and weather events where it's extremely cold or you lose power out. Right? Of course, if you have extra insulation, it helps keep you warm in the extreme cold events. And it acts also as a buffer to reduce heat up, he built up in extreme, hot, extreme heat waves during the cold weather and rain.

The best way to deal with that combination is something called the rain screen system. There is a very scientific approach to it. A lot of people use rain screen in a less discriminate manner - who misuse the term rain screen, but it's designed primarily to avoid moisture buildup in the wall itself and consequently decrease the risk of mold growth.


Ventilation

Once you have control over the shell and the skin of the building, you need to control the air being brought in. Proper ventilation is key. I discuss this a little in my article UPGRADE YOUR HOUSE Part 2: The Solution To Your Sick Home and even more in my article How To Improve Your Home's Indoor Air Quality To Improve Your Health. Biophilic design principles and the right equipment provide fresh air even during extreme events.

Energy Independence

If your house is energy-independent, power outages have very little impact on you. The energy performance of your house is the first ingredient -- the less energy you consume, the more likely onsite power generation such as solar panels (photovoltaic panels) will be adequate to power your home. Net Zero Energy homes and Passive House homes both are able to achieve this fairly easily.


Landscaping

You could consider some landscaping features whether decorative or just a vegetation to act as a sort of wind plow in order to deflect, even just a little, the incoming winds so that they're not blasting straight at your walls and picking up the roof overhangs. In hurricane-prone areas and in areas that are subject to a lot of earthquakes, the structural connections can be designed to resist those forces a lot better so the house is less likely to be picked up, lifted away by a flood or by being blown away by extreme wind.

All these are strategies are proven techniques - ones which are used in different areas but almost never in combination. But we can take a little bit from here and a little bit from there; we can leverage the knowledge gained by industries reacting to their own individual historical hazards. We must combine the techniques because ultimately we're facing a combination of weather hazards. As the range of extreme weather starts to hit us on a more regular basis. So if you need to get more information, please feel free to get in touch using the button below. I'd be happy to speak with you more about this.