Energy-Saving Home Remodeling: The Inside Game

by lcmremodel

Now that we are remodeling with energy efficiency in mind, we get asked a lot of questions by friends and neighbors. The most common, besides “how are you living through all that dust?” is “if I want to improve the comfort and efficiency of my home, which should I do first — replace windows or add insulation to the walls?” The answer in most cases is insulation, but together they really perform.

Whether you are building to net zero or just want to lower your energy bills, windows and insulation are the blocking and tackling of home design — one is flashy, the other not so much, but together they get the job done. If a house is a football team, windows are a noticeable star like a wide receiver.

Their impact on a house is dramatic, flashy and hard to miss. Insulation might be the left guard (see Michael Lewis’ The Blind Side). The left guard doesn’t get mention in the sports pages, but he protects the quarterback’s back from charging defenders.

Reducing the energy load of the home is step 1 in net-zero design; sizing the solar array is the last step. So it’s worth spending time on the X’s and O’s — evaluating various options to improve the home’s defense against unwanted heat gain or loss. Windows and insulation are definitely the key players here.

Which to do first of course depends a great deal on where you live, what your existing windows and walls are, and other factors like solar orientation, tree shading, etc. But for our Long Beach house with no existing wall insulation and original wood windows from the ’50s, the answer was clear.

According to our energy models:

  • Going from nothing to R-13 walls will reduce our heating/cooling load by 33 percent.
  • Installing new low-e dual-pane windows (U/SHGC=0.30/0.29) will reduce our load by 14 percent.
  • Doing both is almost additive, generating a combined heating/cooling load savings of 46 percent.

For our Long Beach house with no existing wall insulation and original wood windows from the ’50s, the answer was clear.

That load reduction means that we reduce the number of solar panels we need on our roof. If the solar panels are the quarterback of the house, a solid defense against unwanted heat gain or loss means the panels can be more impactful and high-step into the end zone. With proper blocking and tackling, even

The stakes are higher than ever for energy efficiency….

a modest solar array has a shot at net-zero. That is real cost savings.

For us, the installation costs were roughly the same on insulation and windows. So performance bang-for-the-buck was best for wall insulation. And our game plan is to vary the type of insulation in each part of the house. Where we are opening walls, we can add traditional fiberglass batts. Where the walls are largely intact, we can drill a few holes and blow in cellulose insulation. Where we have a large attic space, we can super insulate with blow-in cellulose, reaching R-49 performance. Where our attics are narrow, like over the vaulted ceiling, we can use smaller batts and stop at R-19.

Windows come in an almost endless variety of options. In our analysis, springing for even more efficient windows (triple-pane, triple-coated) did not have payback relative to the extra cost. Why? Because our climate is fairly moderate. Move our house to Las Vegas or the Sierras and the high-end windows may have been worth the upgrade. Proper research makes these decisions clear.

So, why don’t more remodels add insulation and windows?

Until now, most remodels were an exercise in making a home more livable, more useful and more attractive. But the game is changing. The stakes are higher than ever for energy efficiency, with several factors generating new interest in energy efficiency improvements like:

1. Rising energy costs.
2. Climate change consciousness.
3. Strict new energy codes encouraging the use of more energy efficient materials.
Innovation by product manufacturers.