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Building for Efficiency: Smarter Walls and Low-Carbon Materials

When we think of energy-efficient homes, insulation is usually the first thing that comes to mind. But not all walls or insulation types perform the same way. The way we design, layer, and build our walls plays a big role in how much energy a home uses and how much carbon it emits over its lifetime.

Let’s explore some common wall setups and how they impact both energy efficiency and embodied carbon, the “built-in” emissions from producing and transporting materials.

Figure 1: High-Performance Exterior Wall

Wall Setups: Inside, Outside, or In-Between

  • Batt Insulation (Traditional Interior Insulation)
    This is the most common setup, using fiberglass or mineral wool placed inside wall cavities between the studs.

Benefits: Easy to install, affordable, and widely available.

Limitations: Studs act as thermal bridges, which are paths where heat escapes and reduce overall efficiency.

  • Outsulation (Exterior Insulation)
    Here, insulation is added outside the wall sheathing, wrapping the home in a continuous thermal layer, like a warm blanket.

Benefits: Strongly reduces heat loss through studs; keeps interior walls warmer and drier.

Limitations: Slightly higher cost and requires careful detailing to prevent moisture buildup.

  • Hybrid Insulation
    A modern approach that combines batt insulation inside with rigid or mineral wool panels outside.

Benefits: Offers a good balance of cost and performance, improves comfort, and lowers heating and cooling demand.

Limitations: Slightly more complex to build.

Exterior or hybrid walls keep homes warmer because they prevent heat from escaping through wooden studs, a common issue in colder regions like the Okanagan Valley.

Reducing Built-In Carbon: Which Insulation Is Greener?

Embodied carbon refers to the greenhouse gas emissions from producing and delivering materials before the home even operates. Choosing low-carbon insulation helps reduce a building’s total footprint.

Figure 2: Embodied carbon spans all building stages from material extraction to the end of life (It excludes the operational stage because that includes energy use during the building’s life, such as heating, cooling, lighting, and appliances, which is considered operational carbon, not embodied) and the carbon impacts of insulation.

A home’s true carbon story starts long before it’s built, from extracting materials to manufacturing and beyond. The type of insulation we choose can make a big difference in this story. Some materials release large amounts of carbon during production, while others can actually store it. Natural fiber insulations like hemp wool or cellulose store carbon during their growth phase, making them excellent choices for low-carbon homes.

The Next-Gen Home: Built for Energy Efficiency

The Next-Gen Home in the Wilden Living Lab is designed to be highly energy-efficient. It features high-performance exterior walls, advanced insulation, and airtight construction that work together to minimize energy loss and keep the home comfortable year-round.

To explore how material choices influence a home’s carbon footprint, we conducted a small experiment. To see how different materials can change a home’s impact on the planet, we ran a test using a Life Cycle Assessment (LCA) tool. This type of software helps simulate how much energy and carbon a material uses, from the time it’s made to the time it’s thrown away.

In our test, we compared the Next-Gen home’s current fiberglass batt insulation with cellulose insulation, which is made from recycled paper. The results were impressive; switching to cellulose could cut the home’s carbon footprint by about 10%. That’s because cellulose actually stores carbon instead of releasing it during production, unlike many regular insulations. This simple change shows that even in a well-built, energy-efficient home, choosing greener materials can make it more sustainable. And the potential doesn’t stop there; using more environmentally friendly materials could lower emissions even further, helping us move to truly zero-carbon buildings.

Beyond Insulation: Materials That Matter

Cutting down a home’s carbon footprint isn’t only about the insulation inside the walls; it’s also about what the walls are made of.

  1. Exterior materials:
    Pick options like wood siding or recycled metal instead of heavy, high-carbon materials like brick or concrete.
  2. Interior materials:
    Use low-VOC paints, reclaimed wood, and natural plasters to create a healthier and more eco-friendly living space.
  3. Smart design choices:
    1. Build smaller but smarter: Compact homes use fewer materials, save energy, and are easier to maintain.
    2. Go modular: Use building parts that can be reused or recycled to reduce construction waste.
    3. Use natural light and passive heating: Design for sunlight and natural warmth to reduce heating and cooling needs.

Energy-efficient walls do more than keep a home warm; they help build a sustainable future. By rethinking both where insulation goes and what materials we use, we can design homes that are comfortable, affordable, and kind to the planet.

The Next Generation Home sold in spring 2023 and data is being collected through sensors while the owners live in the house. Findings are being published on wildenlivinglab.com regularly. To follow the Wilden Living Lab, subscribe to the newsletter.

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