Thinking Beyond the R-Factor

Nancy Polig's house

By Nancy Werking Poling

Insulation. As a writer of fiction I’ve never felt compelled to mention it. Her bungalow, with its freshly painted green shutters and vine-enshrouded front porch, had standard fiberglass insulation with an R-factor of fifteen. But when my husband and I built a home in western North Carolina a year ago, I became more aware of the importance of insulation.

We wanted a home that was environmentally friendly, one that squanders as few of the Earth’s resources as possible. But when we studied green building, everything seemed to carry a hefty price tag. We were fortunate to meet, quite by accident, Melzer Morgan of Falcon Development of NC. Falcon has had extensive experience building Healthy Built Homes, a North Carolina green designation. Fifteen years ago Morgan was trained by Advanced Energy Partners, who teach building science: what works and what doesn’t work in different areas of construction.

Morgan is especially aware of the needs of first-time homebuyers. His question to himself is, How can I make green affordable for everyone? The key difference, he says, is not in the materials he uses, but going the extra mile in the amount of labor. This is how he approaches insulation.

Air moves. Heat seeks cooler places, trying to escape outside in the winter, inside in the summer. Everyone knows that insulation creates a barrier, but some think no further than its R-value. According to Morgan, “The R-value measures the effectiveness of insulation, if it is installed perfectly. Builders sometimes take short cuts, which subtracts from the R-value.”

Where insulation is placed and how it’s situated in relation to other materials, like metals or wood, are part of the formula too.

In our new home Falcon used standard fiberglass insulation, the kind that is free of formaldehyde, with an R-factor of 15. What made its installation green, though, was the close attention the builder paid to sealing the envelope; that is, eliminating places where air can seep through. In the framing of most houses there are energy-wasting voids, spaces through which cold or hot air can pass. Falcon uses framing techniques that allow them to get back in the nooks and crannies. They apply caulk and blow in foam insulation where cracks or other openings might allow the passage of air. Above windows they put in headers, 10-inch blocks of wood, sandwiching half an inch of foam blueboard to prevent thermal-bridging. Thermal-bridging occurs when cold-conductive matter, such as metal, transfers the cold to other materials.

Nancy Polig's insulationOnce the insulation is installed, Falcon calls in a third party to inspect. The inspectors may say, “This needs to be smoother, this crack needs to be filled in.”

So, while friends comment on how attractive our new home is, what counts most isn’t visible. Yet we see evidence of it all of the time. On hot days we open the house up in the evening, close the windows in the morning. The air conditioner doesn’t cut on until three or four o’clock in the afternoon. During this past winter, one of the coldest on record in our area, our combined gas and electric bills didn’t go over $200 dollars a month—this to heat a 2000-square-foot home.

So when it comes to insulation, there are no exciting details for a fiction writer to mention: no sparkling eyes, hair of silk, beguiling smile. Yet quietly and stoically insulation does its job of blocking the invading outside air and protecting the environment. In the frigid temperatures of January we can tell it’s there. In the heat of August we feel its presence. It’s the silent hero of my story.

Okay, so I’m getting a little melodramatic.

Nancy Werking Poling is author of Had Eve Come First and Jonah Been a Woman and Out of the Pumpkin Shell.

5 Responses »

  1. Thanks for this. You have changed how I think about insulation. These ideas will help me even in our very different northern climate. Air still moves up here. I can’t wait for your take on toilets!

    • If you live in a northern clime, R15 won’t even meet the building code. In fact, the traditional wood stud and fiberglass batt construction is the least efficient for a green home.
      The one thing they did get right in the article, is the importance of sealing the house to reduce air infiltration/exfiltration.

  2. Unfortunately, the use of any glass fiber insulation is a mistake from the beginning. Because fiberglass type insulation have no vapor barrier and are subject to the extremes of not only cold and heat but also humidity, the effective R-Value of any fiber insulation is inversely reduced by the increase in ambient humidity. Case in point, studies conducted over 30 years ago by BASF show that with just a 5% humidity factor, the effective R-Value of insulation is reduced by 50%!

    With that in mind, the most cost effective R value is achieved with a rigid insulation such as EPS and as a cost/per r factor, EPS has the highest effective R value per s/f of cost.


  3. What I ended up in my partial remodel with was a compromise/combination. The remodel was on the south facing side of the house and most exposed to temperature variables, so I added 2″ rigid, foil backed insulation to the underside of the roof. The walls have 1″-2″ of spray foam to seal the cracks against air infiltration with unfaced fiberglass batts to fill the rest of the void, since I could not afford to do the whole thin with spray foam. Then on the outside there is the 1/2″ shear panels with a vapor barrier, a 1/2″ foil faced rigid foam layer and a rain screen, which essentially creates a 1/4″ air space between the wall and the siding and lets any rain that gets behind the siding drain away. We had an unusually cool summer last year, but it has worked very well through the winter. Not as beneficial as simply sealing and insulating the north side of the house which I did 10 years ago, but I’m happy.

  4. As the author found out, green building can be affordable. We do it every day at our local Habitat for Humanity. As noted, the biggest “cost” is labor to pay attention to details. We use open celled spray foam insulation in our homes because it is so difficult to get inexperienced volunteers to install any type of bat insulation correctly. The spray foam eliminates many problems relating to installation. We also use about 20 tubes of caulk to be sure all gaps are filled including between 2 studs. We use blue ridgid insulation (taped!!) to reduce thermal bridging. The most recent home has 6″ exterior stud walls. We also use a conditioned attic space. The result are LEED Platinum homes for no more than $10,000 over the cost of built-to-code (usually about $5,000). The great thing is the “cost” to the homeowner is approximately $200/month LESS expense each month going to the mortgage and utilities. In North Alabama (probably not too different than North Carolina), we are averaging $19/month per person on our last 5 homes (3 LEED Gold, 2 LEED Platinum). Specifically, we have one family of 1 adult and 3 teenagers who pay $30-$40 for her entire utility bill each month. That includes gas, water, electic, sewer, city lighting, etc. This is for a 3 bedroom, 2 bath home (2 story) about 1300 SF if you include the conditioned space under the eaves (we left it open for storage or play space).

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