At the end of the day, when you're rolling up your sleeves to build or renovate your own home, the choice between brick and concrete block can feel less like a straightforward building decision and more like a greenwashing minefield. You’ve probably heard whispers that concrete is bad for the planet, that bricks are somehow “greener,” and that terms like embodied energy and U-value are crucial—but confusing. How do you balance your eco-conscious ideals with a sensible budget? Which is truly the more sustainable option for your project?
I'll be honest with you: let me break it down for you, drawing on 15 years of experience in sustainable building, a healthy dose of skepticism, and a trusty old brick sample i carry around like a talisman. We’ll look at the facts, the numbers, and the real-world performance of both materials so you can make an informed choice without getting lost in jargon.
Understanding the Basics: Bricks and Concrete Blocks
Before we dive into sustainability, it’s important to clarify what we’re dealing with.
- Bricks: Typically, these are made from clay that’s been fired in a kiln at high temperatures. Brands like Glen-Gery and Belden Brick Company have been producing these for decades. Bricks come in standard sizes and have a dense, sturdy feel. Concrete blocks: Also called cinder blocks or CMUs (concrete masonry units), these are made from a mix of cement, water, and aggregates like sand or gravel. They’re larger than bricks and often hollow inside, which can affect insulation properties.
Both materials are common in home building, but their production, performance, and environmental footprints differ. Let’s unpack those differences.
Embodied Energy: What Does It Really Mean?
“Embodied energy” is one of those buzzwords that gets thrown around a lot. Simply put, it’s the total energy required to extract raw materials, manufacture, transport, and install a building product. Think of it like the “carbon calories” burned before the material even gets to your wall.
For example, making cement—the main ingredient in concrete blocks—is energy-intensive because it involves heating limestone to very high temperatures (~1450°C), which releases a lot of CO2. Clay bricks also require firing in a kiln, but the energy profile is different.
So, which has a lower embodied energy?
Material Embodied Energy (MJ/kg) Embodied Carbon (kg CO2e/kg) Clay Brick 3.3 - 5.5 0.2 - 0.4 Concrete Block 0.85 - 1.2 0.1 - 0.2Data sources: Various life cycle assessments; note these values can vary by manufacturer and region.
At first glance, concrete blocks seem to have a lower embodied energy per kilogram.
Let me tell you about a situation I encountered wished they had known this beforehand.. But here's the catch: concrete blocks are much lighter and less dense than bricks. You need more volume of concrete blocks to build the same wall area, which often balances out or even tips the scale in favor of brick when comparing the embodied energy per square meter of wall.
So, the “which is greener” question isn’t as simple as looking at raw numbers per kg.
Thermal Mass and Energy Efficiency: The Role of U-Value and Wall Performance
Now, onto U-value, another term that causes confusion. U-value measures how well a material allows heat to pass through it—the lower the U-value, the better the insulation. However, thermal performance in walls isn’t just about insulation; it’s also about thermal mass, which is a material’s ability to absorb, store, and release heat slowly.
Bricks have a higher density and thermal mass compared to concrete blocks. This means they can help regulate indoor temperatures by absorbing heat during the day and releasing it at night, reducing heating and cooling needs.
Concrete blocks, especially hollow ones, have lower thermal mass. However, they can be filled with insulation materials to improve their performance.
Here’s a rough comparison of U-values:
Wall Assembly Thickness Approximate U-Value (W/m²K) Solid Brick Wall 100 mm ~2.0 Concrete Block Wall (hollow) 200 mm ~1.5 (without insulation) Concrete Block Wall + Insulation 200 mm + 50 mm insulation ~0.3 - 0.4So, while bricks offer thermal mass benefits, concrete blocks paired with insulation can outperform bricks in pure insulation terms. But keep in mind: the embodied energy of added insulation materials can be significant.
Durability and Lifespan: The Long Game of Sustainability
One thing I always emphasize is that sustainability isn’t just about upfront carbon or energy costs—it’s also about how long your materials last without needing replacement or repair.
Clay bricks have been used for thousands of years. The Romans, for instance, built structures that still stand today. My worn-out brick sample? It’s a humble reminder of that longevity. Bricks resist weathering, rot, and pests, and require minimal maintenance.
Concrete blocks are also durable but can be more susceptible to cracking or spalling over time, especially if exposed to moisture without proper detailing. However, they’re often cheaper upfront and easier to work with.
Cost Considerations: Balancing Budget with Sustainability
For DIY builders, budget is a big factor. Here’s what you can expect:
- Bricks: Typically range from $0.50 to $2.50 per brick depending on quality, style, and region. Higher-end bricks with special finishes or colors can be pricier. Concrete blocks: Generally cheaper per unit—around $1 to $3 per block—but since blocks are larger, the overall cost for a given wall area can be competitive.
Don’t forget to factor in mortar, labor (even if DIY, your time counts), and any insulation or finishes. Sometimes the cheaper concrete block walls require additional insulation layers, which can add cost and embodied energy.
Eco-Friendly Building Blocks: Are There Better Alternatives?
While bricks and concrete blocks are the common staples, there are some emerging alternatives you might hear about:
- Fly ash blocks: Made from industrial byproducts, they reduce cement use but may have variable quality. Compressed earth blocks: Use local soil and mechanical compression, lowering embodied energy but requiring good site conditions. Recycled concrete blocks: Incorporate crushed concrete from demolished buildings. Better than virgin concrete but still involve cement.
My advice? If you’re considering alternatives, research local availability and durability, and be wary of new materials marketed as “miracle green” without proven track records. The last thing you want is a short-lived wall that ends up costing more in energy and repairs.
Summary: Which Is Greener—Brick or Concrete?
Here’s the nutshell for your project:
For many DIY homebuilders who want a practical, eco-friendly wall that balances upfront cost with long-term performance, clay bricks from reputable companies like Glen-Gery or Belden Brick Company remain a solid choice. They combine durability, thermal benefits, and a relatively moderate embodied energy footprint.
Concrete blocks aren’t inherently “bad” for the environment—they can be part of sustainable construction if paired with thoughtful design, insulation, and local sourcing.
Final Thoughts
Choosing embodied energy of materials between brick and concrete block isn’t about picking a clear “winner” but about understanding the trade-offs and what fits your project, climate, and budget. Remember that sustainability goes beyond just the materials—it’s about how they’re used, the design of your home, and how long it lasts.
In the end, a well-built brick wall carries a bit of history and resilience in every unit—something that, as a skeptic of flashy new materials, I find reassuring. But if budget constraints push you toward concrete blocks, make sure you address insulation and moisture details carefully.
Keep your worn brick sample handy, keep asking questions, and build wisely. The planet, and your future self, will thank you.. Anyway,