Complete Home Energy Score Guide to Insulation

home energy score guide insulation

When we first purchase a home, or go to sell it, we tend to fix the obvious problems: Rotting porch, leaky roof, old plumbing. But there might be other problems that aren’t quite so easy to see from the outside, problems that are costing hundreds of dollars per year in energy bills. Hidden in the walls, insulation is hard to see and more complicated than, say, a hole or a rotten board. This blog post will explore why the Home Energy Score focuses so much on what we don’t look at, and what to do if your home needs an insulation upgrade. 

The Home Energy Score / Insulation Report

Portland’s Home Energy Score Report might as well be called the “Insulation Report”. That’s because most homes in Portland were built before the 1980s, when fully insulating new homes first became a City of Portland requirement. The presence of adequate insulation in the home not only makes it less costly to heat and cool, it also makes the home feel more comfortable by reducing drafts and the hot and cold spots that exist from room to room. Just to show how much attitudes have changed about insulation in 30 years, we now have a Home Energy Score requirement which discloses to home buyers how energy efficient a home really is. And, most of the time, energy efficiency performance comes down to insulation. 

Back to the Basics: What is insulation?

Technically, insulation is any material that stops the transfer of heat, either by conduction (direct transfer), convection (movement of air) or radiation (infrared rays). Insulation works by creating a barrier that slows down all three of these forms of heat transfer. 

Before modern fiberglass and foam insulations were invented, can you guess what the most common type of insulation was? The answer is: Air. In other words, nothing. The first wood-frame homes in the Portland area were built with empty stud cavities, and they were simply cold and drafty — though occasionally people did stuff extra wool inside the walls, or tack old newspapers in there. 

To a time-traveler from the late 19th century, the insulation you can buy at the home improvement store today might seem like a miracle product. It’s lightweight, easy to install, fire-resistant and has soundproofing qualities. To top it all off, insulation can be purchased and installed relatively inexpensively, especially when you consider that it will typically pay itself off in energy savings in just a few years. 

So why isn’t every Portland home already fully insulated?

That’s the big question that Home Energy Scores are trying to address, but the answer, for now, is inertia. It’s the principle that says, an object in motion tends to stay in motion, while an object at rest tends to remain at rest unless some outside force acts upon it. Homes in Portland that were not well insulated when they were built during the housing boom of the 1940’s, 50’s, and onward tend not to have had the problem addressed (unless a homeowner moves in who is especially energy conscious). Why? People are busy, money is tight, and, as we mentioned earlier, insulation is basically invisible. 

The inertia problem is compounded by the fact that Portland has a temperate climate, which means we don’t have to use a lot of electricity to heat or cool a home here. Plus, our utility rates have historically been lower than other parts of the country thanks to hydroelectric power and natural gas. 

In fact, many Portland homeowners don’t even realize that their walls are poorly insulated, or that they’re losing a third of their heated air through gaps around their older windows, until a Home Energy Score assessor comes along and tells them. 

What kind of insulation is best for Portland?

Although it’s true that it doesn’t get extremely hot or extremely cold in Portland, the Department of Energy still recommends R38-60 insulation in attics and R25-30 in the floor for our climate zone. For uninsulated walls, they recommend waiting until the exterior siding needs to be replaced, then installing an insulative sheeting beneath the new siding as well as blowing insulation into the wall itself. 

To choose the best insulation for your home from the many types of insulation on the market, the Department of Energy recommends first figuring out where you want or need to install the insulation, then purchasing insulation based on R-value. This is where the Home Energy Score report comes in: it includes a prioritized list of places that your home needs insulation the most, along with the recommended R-value for each location. 

At the home-improvement store, however, things may get a lot more complicated than the DOE lets on. Here’s a quick guide to some of the industry terms.

  • Batts vs blow-in. These are the two most cost-effective types of insulation products, and will fit the needs of most Portland homeowners. Foam boards or SIPs are great in new construction, but difficult to apply in a retrofitting situation. 
  • R-value vs U-factor. R-value is a rating of the material’s insulative power; the higher the R-value, the better that material protects against conductive heat flow. You may also see U-factor advertised, though it’s typically only used to rate windows and doors. The lower the U-factor, the better the insulative power. For consumers, the key difference between R-value and U-factor is that R-values are additive; you can add an inch of R-13 of insulation to a wall containing one inch of R-6 insulation, for a total R-value of R-19.
  • Faced vs unfaced. Batt insulation is sold with a paper “face” attached to one side, or without (“unfaced”). The “face” is a vapor barrier, and building scientists now agree that it’s not necessary in climates like Portland’s. In short, when buying batt or roll insulation, unfaced is preferred.

Don’t Forget to Air Seal

In addition to marking where, and to what R-value, your home is insulated, your Home Energy Score Assessor will check to see that your home is air sealed. Don’t skip this step! If you’ve spent time and money adding insulation to improve your Home Energy Score, you’ll lose all those insulative benefits by air leakage around doors and windows. Check out our full blog post on air sealing here.

Ready for your Home Energy Score report? Whether it’s your first time getting the score or you want a re-score after improvements, we’re happy to help. Just call or schedule online!