According to the City of Longmont Building Services, “The City of Longmont has adopted the 2024 International Codes, along with the Metro Cohort Model Code and Colorado Wildfire Resiliency Code as of July 1st, 2026.”
Why insulate
Why do Longmont homes need insulation attention?
Longmont's housing stock skews old by this service area's standard — only Niwot's skews older. Roughly 4 in 10 Longmont housing units predate 1980, and the median home dates to about 1991 (Census Bureau American Community Survey 5-year estimates, 2020-2024) — old enough that original attic insulation, where it exists at all, is a reasonable bet to be running well under today's targets.
What makes Longmont different from a typical Front Range insulation market isn't the housing — it's the utility map. Longmont Power & Communications, the city's own municipal electric utility, doesn't cover the whole city. Verified against the Colorado Geospatial Portal's own electric-utility-territory data: roughly 61% of Longmont's area is LPC electric; the rest splits between Xcel, Poudre Valley REA, and United Power, concentrated on the city's west and east edges respectively. Two homes a few blocks apart can have different electric utilities, and only one of them can access the Efficiency Works rebate described below.
The practical result: every Longmont insulation quote should include a check of which utilities actually serve the address, not just which town it's in. Xcel's gas-and-electric rebate applies citywide regardless of which electric utility a home has. The Efficiency Works rebate does not — it requires LPC electric service specifically, and the only way to know for certain is to check the electric bill.
According to the U.S. Census Bureau, the ACS 5-year estimates are available for the nation, all states, and places (i.e., towns or cities) — the geography behind this site's town-by-town housing-age figures, drawn from the 2020-2024 release, table B25034 for year structure built and table B25035 for median year structure built.
Rebates & credits
What rebates can Longmont homeowners claim?
Xcel Energy — applies to every Longmont address, regardless of electric utility:
- Xcel Energy Insulation and Air Sealing Rebate — pays a percentage of project cost for gas-heat customers against per-measure caps; ask your contractor for the current rate. A reduced tier applies to Xcel electric customers with central air conditioning whose heating fuel is not provided by Xcel Energy. Requires a participating contractor and, unless a first blower door test already finds the home tight enough by Xcel Energy's own measure, a documented 20% reduction in CFM50.
Efficiency Works — Longmont Power & Communications electric customers only, not every Longmont address:
- Efficiency Works Retrofit Rebate — pays a per-square-foot incentive for most insulation measures, a separate per-square-foot rate for flat-ceiling attic insulation, and a tiered flat payment for air sealing based on measured reduction in air loss from a blower door test (four tiers, at above 15%, above 25%, above 33%, and above 50% reduction); ask your contractor for the current rates. Requires an Efficiency Works assessment first, a listed service provider, and applies only to residential electric customers of Longmont Power & Communications — check your electric bill to confirm.
Boulder County EnergySmart — income-qualified only as of January 1, 2026:
- Boulder County EnergySmart — for households at or below 100% of area median income, 50% of project cost up to an annual cap the county publishes on its own program page, subject to R-60 attic / R-19 wall / R-30 sub-floor minimums and required blower-door testing. Standard (non-income-qualified) rebates ended January 1, 2026.
These are three separate programs from three separate sources. Of the three, only Efficiency Works publishes anything we've found on combining them: an illustrative table that lists its rebate beside an Xcel figure and totals the two for one example project. This site doesn't adopt that total, because Xcel's own rebate sheet is silent on the combination. We've found nothing that addresses Boulder County EnergySmart alongside either. Ask your contractor to confirm which apply to your specific address before assuming a total.
According to Efficiency Works (Platte River Power Authority program, for Longmont Power & Communications electric customers), Efficiency Works pays a per-square-foot incentive for most insulation measures (conditioned crawl space, basement wall, cantilever floor, exterior wall, cathedral ceiling, conditioned attic) and a separate per-square-foot rate for flat-ceiling attic insulation, available only to residential electric customers of Longmont Power & Communications, with the current rates published on its own incentive sheet.
For current Xcel rebate amounts and program rules, see the Xcel Energy insulation and air-sealing rebates page. For Efficiency Works eligibility and current incentive values, see Efficiency Works home rebates. For Boulder County EnergySmart's current income limits and rebate amounts, see Boulder County EnergySmart rebates. Eligibility may depend on which electric utility serves your address, program funding levels, and qualifying product specifications.
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We've got your info and are routing it to a local pro. When they call, here's what to look for in the quote you receive: (1) R-value target — ask what R-value your contractor is quoting to, in writing, and confirm the figure your permit is reviewed against with the City of Longmont's building department. (2) Air sealing scope — insulation alone does nothing if air leaks aren't sealed first, and Xcel requires a blower door test to rebate it. (3) Rebate handling — ask which programs your specific address qualifies for. Xcel and Efficiency Works are separate programs with separate paperwork, and not every address qualifies for both. (The federal IRA Section 25C tax credit ended December 31, 2025 — no federal insulation credit applies to 2026 work. Xcel Energy's insulation and air-sealing rebate remains active for its gas and electric customers. Longmont Power & Communications electric customers may separately qualify for an Efficiency Works rebate — check your bill to see which utility serves your address. Boulder County EnergySmart pays a third, income-qualified-only rebate as of January 1, 2026.) (4) Removal scope — older homes often need old insulation removed before new install. If a quote skips all four, get another quote.
Frequently asked
What do Longmont homeowners ask most about insulation and rebates?
How do I know if I have Longmont Power & Communications or another electric utility?
Check your electric bill — the utility name is on it. LPC bills come from the City of Longmont; if your bill instead comes from Xcel Energy, Poudre Valley REA, or United Power, you have a different electric provider and the Efficiency Works rebate described on this page does not apply to your address. Xcel's gas-and-electric insulation rebate applies regardless of which of the four serves your address.
Do the Xcel and Efficiency Works rebates add together?
We can't independently confirm that they do. Efficiency Works publishes an illustrative combined total — its incentive sheet lists an Xcel figure beside its own and adds the two for one example attic project — so a published source does address the combination. This site doesn't adopt that total: Xcel's own rebate sheet is silent on it, and the Xcel figure in Efficiency Works' table doesn't match any Xcel per-measure cap we've independently verified. Ask your contractor or the programs directly before counting on Efficiency Works' combined figure.
Should I do this if my Longmont home was built after 2010?
Probably not yet. Post-2010 Longmont homes were built to recent code, with attic insulation well above the pre-1990 baseline. If your bills are normal and comfort is fine, hold the money. The 10-15 year mark is typically when settled batts and unsealed penetrations start costing you — that's when it's worth another look. We'll tell you straight when we look at it.
What does Longmont's Efficiency Works rebate actually pay?
For LPC electric customers only: a per-square-foot incentive for most insulation measures, a separate per-square-foot rate for flat-ceiling attic insulation, and a tiered flat payment for air sealing based on measured leakage reduction, in four tiers — above 15%, above 25%, above 33%, and above 50%. Efficiency Works publishes the current amount for each on its own rebates page. Incentives are capped at 100% of project cost and require an Efficiency Works assessment first.
Do you serve all of Longmont?
Yes — every Longmont neighborhood and ZIP code, plus Lafayette, Louisville, and Niwot. Service areas listed at the bottom of this page show where we work regularly.
Service area
Where do you provide insulation services in and around Longmont?
- Old Town Longmont
- Prospect New Town
- Southmoor Park
- Renaissance
- Quail Ridge
- Sunset Golf Course area
- Downtown Longmont
- 80501
- 80503
- 80504