Ontario Winters and Real-World Performance
I still remember my first winter visit to Castleton.
I'd packed for survival. Wool sweaters. Thick socks. Extra layers. The whole works.
After all, I was heading to a rammed earth home in rural Ontario over Christmas, with temperatures hovering around -20°C. I wasn't entirely convinced I'd be comfortable.
I was wrong. In fact, I was overpacked.
The house felt warm, steady, and comfortable in a way that surprised me. There were no cold drafts, no hot-and-cold swings, and no sense that the weather outside was dictating how the house felt inside.
I remember thinking, "Wait. How is this possible?"
Years later, after spending time in more rammed earth homes and speaking with homeowners, I've learned that my experience wasn't unusual.
Heather Boyd, who lives in one of our rammed earth homes in Prince Edward County, describes it this way:
"It's hard to explain until you've lived in one. The house just feels comfortable. The temperature stays remarkably consistent, and even during the coldest parts of winter, it never feels like you're fighting against the weather."
That's a comment we hear often.
So What's Going On?
The reason my Castleton experience was so surprising comes down to something called thermal mass.
Unlike a conventional wall, a rammed earth wall can absorb, store, and slowly release heat energy. During the day, the wall stores heat from the sun and from the home's heating system. Later, as temperatures drop, that stored energy is gradually released back into the living space. Sounds like magic, but it’s even better - it’s science.
If you've ever walked into a basement on a hot summer day and noticed how cool and stable it feels compared to the outdoors, you've experienced thermal mass at work.
The result isn't necessarily a warmer home. It's a more stable one.
Temperatures fluctuate less. Rooms feel more consistent. The home isn't constantly chasing the weather outside.
For many homeowners, that's what comfort actually feels like.
If Rammed Earth Is So Good, Why Do We Still Need Insulation?
This is one of the most common questions we hear. The short answer is that thermal mass and insulation do different jobs.
Insulation slows the movement of heat through a wall. Thermal mass stores heat and releases it slowly over time.
One doesn't replace the other.
In fact, some of the best-performing homes use both.
Aerecura’s rammed earth homes are carefully designed to combine the benefits of thermal mass with modern insulation strategies, high-performance windows, and airtight construction. Each component plays a different role in creating a comfortable, energy-efficient home.
Modern Rammed Earth Meets Modern Building Science
One of the biggest misconceptions about rammed earth is that it's an old building method trying to solve modern problems.
In reality, today's rammed earth homes combine ancient building wisdom with modern building science.
Careful detailing helps manage moisture. High-performance windows reduce heat loss. Air sealing minimizes drafts and unwanted air leakage. Well-designed insulation assemblies work alongside the thermal mass of the walls.
The goal isn't simply to build a beautiful wall.
It's to create a home that performs exceptionally well in a real Ontario winter.
Comfort Is More Than a Number
When people talk about energy efficiency, the conversation often focuses on heating costs, energy ratings, and performance metrics.
Those things matter.
But comfort matters too.
A home can be technically efficient and still feel drafty, uneven, or uncomfortable.
What many rammed earth homeowners notice is the feeling of stability. Temperatures change more gradually. Rooms feel comfortable throughout the day. The home feels connected to the seasons without being at their mercy.
It's difficult to measure, but easy to feel.
Built for Ontario
Ontario winters are demanding.
We deal with deep freezes, freeze-thaw cycles, wind, snow, and increasingly unpredictable weather. Homes need to be resilient, durable, and capable of performing year after year.
Rammed earth has been used around the world for centuries because of its durability. When paired with modern building science and thoughtful design, it creates homes that are built to last for generations.
Looking back, I realize I arrived in Castleton expecting to test a theory.
Instead, I experienced a home that simply felt good to be in.
Lindsey in Castleton, overdressed.
About the Author
Lindsey Van De Keere is a storyteller, marketer, and sustainable building advocate with Aerecura. She spends her days translating building science into plain language and helping homeowners understand what it feels like to live in homes built for comfort, durability, and generations to come.