One of the most important steps in achieving a decarbonized home is also one of the least sexy: insulation. While heat pumps are critical, it’s also important to make sure your HVAC doesn’t have to work overtime due to a leaky building envelope, window, or door.

In this article, we’ll discuss the importance of insulation, the many materials you can use to insulate your home, and how to save money and reduce your payback period.

So, why (and where) is insulation necessary?

Why do we wear sweaters and thick woolen socks in the winter? To insulate our bodies from the cold!

It’s the same principle with buildings; insulation is like a sweater for your building envelope, keeping your paid-for warmth in and the cold winter air out.

Most homes already have some level of insulation, required by state energy codes (for example, see California’s 2019 Insulation and QII Requirements). However, according to ENERGY STAR, 90 percent of U.S. homes could use an insulation boost.

We’ve all been in poorly insulated homes. Even when all the windows and doors are closed, it can still feel drafty. The floor is barely warmer than an ice-skating rink. And worst of all, it’s easy for heating bills to balloon out of control. Strategic insulation can alleviate these issues (or prevent them altogether in new construction).

So, where to start? Because heat rises, it often escapes through tiny holes in the attic, contributing to the stack effect in which cold air is pulled in through the bottom of the building. Therefore, the attic is the best place to start adding insulation upgrades.

After attics, it’s also important to insulate unconditioned rooms like garages, basements, and foundations.

Improving efficiency without increasing emissions

You might picture textured white foam (spray foam) or what looks like squares of pink cotton candy (fiberglass batts). While these varietals are certainly common, there are a number of different materials you can use to keep your home cozy.

Spray foam performs especially well (it’s great for sealing gaps) but often contains hydrofluorocarbons (HFCs) that contribute to global warming 1,400+ times more than carbon dioxide. Plus – do you really want to spray petrochemicals all over your house?

From an embodied carbon perspective, organic materials are your best bet (but they do come with drawbacks). Fiberglass and stone mineral wool are both derived from natural materials. However, their manufacturing processes require extreme temperatures (2,700+ °F), and achieving temperatures that high is extremely energy intensive.

Other eco-friendlier materials, such as hemp, recycled denim (yes, literally old jeans), and sheep’s wool exist that require less processing, and importantly, no mining. Thus, they contain far less embodied carbon. However, they’re often more expensive than their petrochemical counterparts. Additionally, not all organic materials used for insulation offer adequate protection against fire, moisture, and pests.

Don’t break the bank

The cost of insulation materials themselves is not tremendous. However, like most decarbonization projects, paying for skilled labor and professional expertise can cost thousands of dollars.

Firstly, federal weatherization rebates through the Inflation Reduction Act’s HEEHRA program will soon be available. Income-qualified individuals can receive up to $1,600 for ventilation, sealing, and insulation upgrades. Households with enough tax liability can currently apply for up to $1,200 for insulation and air sealing, as well as up to $500 each for doors and windows in tax credits (25C).

In addition, many state and utility incentives exist to offset the cost of insulation upgrades. For instance, Efficiency Maine offers an $8,000 rebate for low-income Mainers looking to weatherize their homes, and $4,000 for households of any income.

Similarly, Mass Save will pay for 75+ percent of insulation upgrades for owner-occupied homes. The organization also provides a free Home Energy Assessment to establish how much insulation and air-sealing is necessary.

Check out the Spotlight States dashboard on Buildings Hub to browse more than 100 state and utility incentives.

Photo Credit: Erik Mclean via Unsplash

About the author: Noah Gabriel

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