The roof affects your energy bills, but less than roofing companies tend to imply. What sits under the roof matters far more than what sits on it, and the single most useful thing to know is which work pays back and which does not.
The honest ranking
If you are spending money to cut heating and cooling costs on a Chicagoland house, roughly in order of return:
1. Air sealing the attic. Cheap, unglamorous, and the biggest single win in an older house. 2. Attic insulation to R-49 or better. Moderate cost, reliable payback. 3. Balanced attic ventilation. Modest cost, and it also prevents ice dams and extends shingle life. 4. Windows and doors. Expensive, slower payback than any of the above. 5. Shingle colour. Effectively nothing in this climate.
The first three all live in the attic. They are covered in detail on our Chicago weather page, because the same work stops ice dams. If you only read one thing about roofs and energy, read that.
Why ventilation does two jobs
An attic that cannot breathe gets extremely hot in July. That heat radiates down through the ceiling and your air conditioning fights it all afternoon. It also cooks the shingles from underneath, which shortens the life of the roof you just paid for.
The same ventilation keeps the deck cold in February, which is what prevents ice dams.
Balanced means intake at the soffits and exhaust at the ridge, working together. Ridge vents with blocked or absent soffit intake do very little, and blocked soffits are common because insulation gets pushed into them during a top-up. Baffles keep that channel open, and they cost very little when someone is already up there.
Roof colour, briefly
A reflective roof surface genuinely runs cooler, and ENERGY STAR rated products cut peak cooling demand by 10 to 15 per cent in the climates where that has been measured.
Chicago is not one of those climates. Energy modelling counts a cool roof as a cooling saving and a heating penalty, and our heating season is long enough that the two largely cancel. Choose your colour on how the house looks. Our materials and colour page goes into this properly.
Solar, and why the sequence matters
If solar is anywhere in your plans, the roof decision and the solar decision are the same decision.
Panels last around twenty-five years. So does an architectural asphalt roof. Fitting panels to a roof with eight years left means paying to remove and refit them when the roof is replaced, and that cost is entirely avoidable by doing the roof first.
So the sensible order is: if the roof is over about fifteen years old, replace it before or at the same time as the panels go up. If it is newer than ten, fit the panels and do not worry.
Between ten and fifteen is a judgement call worth having someone look at, because the answer depends on the actual condition rather than the number.
It is also much cheaper to run conduit and mounts while the roof is off. Anyone quoting both at once should be able to show you the saving.
Proliance handles both roofing and solar, which is the reason we are able to sequence them together rather than sending you to a second contractor.
Skylights
Skylights are the most common roof-related heat leak in a Chicago house, and the oldest ones are usually the worst.
A single-glazed or failed double-glazed unit loses heat all winter and gains it all summer. If your skylight has condensation between the panes, the seal has gone and it is no longer insulating.
The time to replace one is when the roof is off. The flashing has to be redone anyway, and doing it as a separate job later means disturbing a new roof.
What does not pay back
Two things get sold on energy grounds that do not really earn it in this climate.
Radiant barriers work well in hot southern attics where cooling dominates the whole year. In a heating climate their benefit is much smaller, and they do nothing for the heating half of your bill.
Heat cables are not an energy product at all. They are an ice dam symptom treatment that consumes electricity every winter and leaves the cause untouched. If someone offers heat cables as a solution rather than a stopgap, ask what they propose to do about the attic.
Where to start
If your upstairs rooms are hot in summer and cold in winter, or you get ice dams, the attic is where the answer is, not the shingles.
Proliance inspects roofs across the Chicago metro at no cost and the report covers ventilation and attic condition, not only the roof surface. Our inspectors are HAAG certified. Call 800-613-4373.
Sources
- US EPA, cool roofs and peak cooling demand
- US Department of Energy Building America Solution Center, attic air sealing and insulation
- University of Minnesota Extension, R-49 cold-climate attic insulation guidance
