ECONOMIC CENTS: Improving Home Insulation
If R values and the impact of insulation on your heating bill have you confused, Bruce Saller is here to explain it all in this week's Economic Cents article.
By Bruce Saller
WRITER
The recent Joint Legislative Audit & Review Commission Data Center report and Dominion Energy’s Integrated Resource Plan project the need for significant new electrical generation capability over the next 15 years. It will be very difficult for Dominion to add enough green energy to support this growth, along with replacing their current fossil fuel generation. Reducing our electricity usage will be vital to Dominion achieving its 100% green energy goal.
Heating and cooling our homes is the largest use of residential energy, according to the U.S. Energy Information Administration. One way to significantly reduce this cost is to add insulation. There are three main types of home insulation:
Fiber insulation in rolls or batts (pre-cut, flat pieces)
Rigid insulation, typically thick foam
Blown-in or loose-fill cellulose or fiberglass
The thermal resistance (R value) of insulation indicates how well it works. Fiber insulation generally comes in three thicknesses:
R13 (3.5”) for 2x4 framed exterior walls
R19 (6.25”) for 2x6 framed exterior walls and under floors
R30 (9”) for attics.
Rigid insulation is generally R10 (2”) and is used on basement/crawl space walls and on the outside of exterior walls. Blown-in insulation has a R value between 2-4 per inch, depending upon the material used and its density. Blown-in insulation is used in attics and to fill existing uninsulated exterior walls.
The Environmental Protection Agency recommends the following insulation for our area (Climate zone 4A):
Attic: R60
Under floor: R19
Basement/Crawl Space Walls: R10 rigid or R13 batt
I expect most homes in the area have less than R60 in the attic and no insulation on basement or crawl space walls as the above standards only took effect in 2021. So, if your attic has R30 insulation, adding another layer of R30 insulation will reduce your attic heat loss by 50%.
There is a federal tax credit of 30% of the cost of adding insulation (up to a $1,200 credit). Note – the new administration may eliminate this credit in 2025, so act now to ensure you receive the credit.
Another cause of home heat loss is through single-pane or gaps in windows. Replacing the windows can provide the greatest energy savings, but it costs several hundred dollars to replace each one. A less efficient but very inexpensive option is to install indoor shrink window kits. These can reduce heat loss up to 35% and only cost about $2 per window (Amazon example).
So, please consider adding additional insulation to help solve our pending energy crunch.
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Hmmmm....yeah, but no.
Consider me properly triggered.
Guess I'll Monday morning quarterback on Friday. Though again, I do sincerely respect Mr Saller bringing the issue up.
Let's see, EPA may recommend R13, but even the Code of Virginia requires at least R15 batts now in 2x4 walls, and most new construction builders that care are using 2x6 walls with advanced framing (California corners, ladder framing, insulated headers, limited jack studs and king studs) and/or continuous insulation in conjunction with the batt/blown in insulation. Have been for a while.
And rather than R19, R20 or R21 batts or blown-in products are common now. Same labor, better product. Doesn't sound like much but ~5-10% increase in the amount of insulation applied.
And while many builders may loudly proclaim that they build their homes to code, to those who see other builders successfully go much farther through knowledge and technique while still delivering a profitable product, that sounds a lot like
"If I built it any worse, they'd lock me up..."
These relatively low-cost steps provide wonderful return on investment which should be a primary goal of both homeowners and builders. Whether renovating or building new construction.
But insulation should go hand in hand with air sealing, which is a whole other matter. If it doesn't, you've got an air filter, not insulation.
And though single pane windows ARE horrible - they are exceedingly rare now days.
Usually, they are located in homes that are restricted by historical limitations or are so decrepit that they have much bigger problems - such as holes that need air sealing.
Which can return much better returns at significantly lower prices than replacement windows.
(But should only be done as part of a whole house approach due to concerns not only with proper return on investment - but indoor air quality issues such as carbon monoxide poisoning).
Replacement windows are more energy efficient than single pane, but they are also typically expensive and may not return their costs as quickly as other options. If ever.
Point is, there are options. Many. But also considerations.
Cookbook applications may not work as well as having an impartial evaluation.
And those using them may find themselves frustrated with the results which will turn them away from pursuing it further than if they had a sound strategy to begin with.
So, what to do?
If you, like many in this area, use Dominion Energy - they provide two different options for having such an evaluation. Info can be found here:
https://www.domsavings.com/home-program/home-energy-evaluation
Check it out.
If you don't have Dominion, it is worth checking with your provider to see if they offer similar options. They probably do.
If you want to find out more about the building science and terms used here, check out the Building America Solution Center operated by the DOE:
https://basc.pnnl.gov/
A little wonky to start out, but the search engine is very good. As are the articles visuals, and links. Even better, they are constantly updated as building science evolves.
PS. Though I am a licensed Virginia Residential Building Energy Analyst / HERS Rater, I am neither participating in the above program nor soliciting new work. I've got all that I want. That is not my purpose.
But I do think it's better for all if you take a systemic approach that is based upon a plan that considers your home, your goals, your options, and your budget.
An objective assessment from someone with knowledge of those things should be your first step.
THEN you can develop the best strategies based upon what works for you and yours.
That means not only considering the valid long term climate concerns that Mr Saller and I share, but also your immediate concerns; including financial, home comfort, safety, and resilience.
A systemic "whole house" approach will do that.
Start there.
Best wishes.