Recently I talked with two different potential new clients about renovating their homes. Two things on both of their lists were new siding and new shingles. I perked right up because those are both great opportunities to make a home more energy efficient, and if you pass up the opportunity it will be a loooong time before you have another. Let’s face it, energy efficiency usually isn’t the main thing that makes us want to renovate our homes. The need to move the Master Bedroom to the first floor, the desire for a more functional Kitchen, and even wanting to update the look of the house are the kinds of things that motivate most renovations. But if you look for opportunities to improve energy efficiency when you do those projects, you can keep the energy performance of your home up to date right too.
Siding: insulation Siding is a big opportunity because there are just 3 places you can put insulation into a wall: inside the studs, between the studs, and outside the studs. Most existing homes only have insulation between the studs. If your house doesn’t have any insulation at all between the studs (like my 1959 house when I moved in), you can add it by making small holes in the walls and blowing insulation into the cavities. That’s a good start, but not enough to make a house with 2×4 walls meet the standards required by code for new construction today, and I think most of us would like to have our homes do better than meet minimum requirements. 2×4 wall cavities can only hold about R13 or R15 of insulation, and the Ohio Residential Building Code now requires cavity insulation of R20 (which needs a 2×6 wall), or R13 between the studs plus R5 of continuous insulation.
How can you get more insulation in the walls of an existing house? Most renovations don’t involve removing the drywall on the interior, so adding it inside the studs isn’t practical, and making the existing studs thick enough to hold more insulation between them isn’t possible. So when someone is planning to replace the siding on the outside of the house, it is a golden moment of possibility for adding a layer of continuous rigid insulation on the outside of the studs! And having insulation continuous rather than just between studs makes it even more valuable, because it reduces thermal bridging: the heat loss allowed through the studs themselves.
Roofing: insulation and solar Shingle replacement gives you a similar opportunity for more insulation. This can be especially helpful with cathedral ceilings or finished attic spaces, including the 2nd floor of Cape Cod style houses. For these houses with small rafters, it’s great to be able to have more insulation than will fit in the rafter cavity. After tearing off the existing shingles add a layer or two of rigid insulation: 2″ of polyisocyanurate will add R11, or 4″ will add R22 to the R value of the insulation between the rafters. As with the exterior wall insulation, this reduces the thermal bridging through the wood of the rafters. The first few years of a roof’s life is also the best time to maximize the value of adding solar electric to your home. The lower cost of panels and the tax credit of 26% for solar electric systems installed before December 31, 2022 means you will pay off a solar electric system in about a decade, and after that you get free electricity! But it doesn’t make sense to put a new solar system on top of shingles you will need to replace soon: shingles over 8 years old should probably be replaced before you install solar panels. So if you have some south facing roof area and are planning on new shingles, it’s a great time to add a solar system! For more information check out the Solar United Neighbors website.
And you can learn more about the Residential Renewable Energy Tax Credit here.
Now I couldn’t write about energy efficiency improvements without mentioning energy audits. I recommend an energy audit before you do ANY kind of renovation. One program that helps to identify the “low hanging fruit” for saving energy is the Dominion East Ohio Home Performance with Energy Star program. For $25, Building Performance Institute certified professionals come out with specialized equipment to identify the major areas where your home is losing energy. The best part is that you can then get a substantial rebate on any work you have done from their list of recommendations, from insulation to a new furnace.