If you’re building a carbon-conscious house, you’re probably obsessing over choosing the best heating and cooling system. As well you should; according to the U.S. Energy Information Administration, heating and cooling accounts for more than half of a home’s energy usage. A poor choice can bloat your carbon footprint for years to come.

But what about insulation? You know you need insulation to keep your carbon footprint as small as possible, but have you considered the carbon impact of the insulation itself?

Insulation choice greatly affects the carbon footprint of your home, both in terms of embodied carbon and ongoing operational emissions. Depending on what you choose, insulation can contribute to the embodied carbon footprint of your home, or actually act as a carbon sink (that is, sequester carbon).

The two key factors to consider when choosing insulation are performance (which will determine the operational carbon footprint) and materials (which will determine the embodied carbon).

Given that heating and cooling represents an average 51% of a home’s energy consumption, performance (insulation value) is an important factor. Under-insulate your home and you’ll literally pay for it in higher utility bills (not to mention carbon emissions) for years to come.

The state of California has some of the nation’s most strict insulation requirements, which provide a great guideline. The CA Building Energy Efficiency Standards (Title 24) aren’t a light read, but any reputable architect, builder, or Title 24 professional will be able to advise you on what’s needed for your climate zone. At Plant, all the homes we design exceed California Title 24 insulation requirements.

Materials vary widely in performance and embodied carbon. Some perform extremely well, like extruded polystyrene (XPS), but have a very high embodied carbon. Other materials don’t perform as well, like straw bale, but actually sequester carbon. The best choice for your home should be the material that meets the performance needs for your area’s climate zone with the smallest amount of embodied carbon.

If you’re ready to really do your homework, the good folks at Zero Energy Project wrote a detailed article comparing the carbon and health effects of different types of insulation.

At Plant, we use ECOBATT insulation for all the homes we build. We chose ECOBATT because it ranks relatively low on embodied carbon, while scoring very high points for occupant health and safety: It’s GREENGUARD Gold certified, meaning it has met rigorous third-party chemical emissions standards. It’s also made from a propriety glass mineral wool, which uses a minimum of 50% recycled glass and a bio-based binder, so it’s free from the formaldehyde that’s used in traditional fiberglass products.

The specific R-value we use varies by project; our patented Plant Building System allows us to tailor the insulation value to the climate zone where the home is being installed. With projects spanning desert, mountain, and coastal environments, we use a range of ECOBATT products to ensure optimal thermal performance in every home.