Definition
What is energy audit, and how does it work?
A home energy audit is a comprehensive assessment of how your home performs thermally and how it loses energy. The audit produces a prioritized list of upgrades — which improvements pay back fastest, which programs cover them, and what realistic cost ranges look like. The audit doesn't fix anything; it tells you where to spend your insulation dollars.
The standard audit toolkit includes three measurements. First, the blower door: a calibrated fan mounted in a primary door depressurizes the home to -50 Pascals while measuring the air-flow needed to maintain that pressure. The result is reported as ACH50 (air changes per hour at 50 Pa) — a normalized measure of how leaky the building envelope is. Second, infrared thermal imaging: a thermal camera operated during depressurization reveals cold spots where insulation is missing, settled, or bypassed by air leakage. Third, combustion safety: gas appliances are checked for carbon monoxide spillage and proper draft under depressurization conditions.
The deliverable is a written report with prioritized recommendations: e.g., "Air sealing the attic plane and topping up to R-60 will reduce heating cost meaningfully and qualifies for the 2026 Xcel Energy Insulation and Air Sealing Rebate plus the Whole Home Efficiency Bonus when bundled with two more measures." Specific programs, specific paths, and a cost estimate specific to your home from the crew that scopes the work. Most audits identify 4-8 distinct opportunities ordered by payback.
Honest about limitations: an energy audit doesn't directly improve your home; it produces a roadmap. The improvements still need to be done by a separate crew (or the same crew on a follow-up visit). And the audit can only see what's accessible — if the attic hatch is buried, the audit will note that the attic wasn't fully assessed. Pre-audit prep (clearing access, providing recent utility bills) maximizes the value of the visit.
We focus on retrofit projects for existing Denver homes — assessment, removal where needed, air sealing, and installation tailored to homes that are already built and lived in. New construction insulation follows a different process and is typically handled through general contractors and builders; if you're working on a new build, we can refer you to a contractor experienced with new-construction insulation scope.
According to Xcel Energy's residential rebate summary, the qualifying minimum standard for the air sealing rebate is a 20% reduction in CFM 50 — cubic feet per minute at 50 pascals — which requires a blower door test before and after the work; the insulation rebates are qualified by post-job R-value, not by leakage reduction.
Qualification signals
Who needs energy audit in Denver?
A home energy audit is most valuable when you're about to spend significant money on insulation or HVAC upgrades and want to know which order to attack the work in. The strongest cases: high heating or cooling bills with no obvious cause, comfort issues you can't pinpoint (one cold room, drafty bedroom, hot upstairs), planning a major renovation that includes envelope work, or wanting the third measure identified for you (the 2026 Xcel Whole Home Efficiency Bonus needs three or more qualifying measures within two years of enrolling, and an audit is how most homeowners pick the third).
When an audit is less critical: clear, single-cause comfort problems with obvious solutions (e.g., visible R-11 attic insulation in a 1970s ranch — the prescription is obvious without an audit), homes already audited within the last 2-3 years where conditions haven't changed, or new-construction homes from the last 5-10 years, where a build to the code of its own year rarely hides the gross air-leakage or missing-insulation defects an audit is best at finding. Note that this is not the same as being at today's requirement: a 2016-2021 Denver build was permitted against an R-49 ceiling, which the 2021 IECC's R-60 minimum for Climate Zone 5 has since superseded — a ruler in the attic answers that for free.
Cost & the cost of waiting
How much does energy audit cost in Denver — and what does waiting cost?
No primary source publishes a Denver-specific audit price, so this page doesn't print one. A standard assessment is 2-4 hours on-site with a blower-door test, infrared scan, combustion safety check, and written report. Premium audits add extended diagnostics — duct leakage testing, room-by-room pressurization, a thorough HVAC analysis.
Cost drivers and rebate paths: home size (larger homes take longer to audit and price accordingly); whether the audit is bundled with subsequent insulation work (many crews offer the audit free or at a heavy discount when the audit-recommended work is scoped through them); Xcel rebates part of the audit price as its own measure; Xcel's income-qualified programs may cover the audit, with eligibility set out on Xcel's own program pages.
Every winter you delay a real attic-and-air-sealing upgrade on a pre-1990 Denver home, you're heating the attic through the ceiling.
According to the International Energy Conservation Code, the 2021 IECC sets a minimum ceiling insulation R-value of R-60 in Climate Zone 5 under Table R402.1.3, and Section R402.2.1 allows R-49 to satisfy that requirement only where the full height of uncompressed R-49 insulation extends over the wall top plate at the eaves.
Cost figures are conservative ranges. The free in-home estimate gives exact numbers based on your home and required pre-work — not a range.
Denver context
What's different about energy audit in Denver?
Denver's 5,280-foot elevation affects blower-door measurements: the lower atmospheric density means raw CFM50 readings need an elevation correction factor to compare against sea-level benchmarks. Reputable auditors apply this correction automatically in the report; less experienced crews sometimes report uncorrected numbers that overstate envelope tightness. If you're comparing audit reports, confirm the auditor applied the elevation correction.
IECC 2021 R402.4.1.2 prescribes 3 ACH50 as the air-leakage target for new construction in Climate Zone 5B (Denver); the companion 2021 IECC ceiling-insulation table (Table R402.1.3) sets an R-60 ceiling minimum for the same Climate Zone. Existing Denver homes vary widely: tight modern builds commonly test 4-6 ACH50; mid-century homes 8-12 ACH50; pre-1940 historic homes can test 15-25 ACH50 or higher. The audit benchmarks your specific home against the relevant code reference and identifies the highest-leverage spots to address.
Combustion safety on gas-fired furnaces, water heaters, and fireplaces deserves specific attention in Denver. The high altitude affects combustion air requirements; some gas appliances commissioned at sea-level specs can run rich (incomplete combustion, elevated CO) at Denver altitude. The audit's combustion safety check verifies draft and CO levels under depressurization — the worst-case scenario any appliance is likely to face.
An energy audit also identifies whether your existing insulation should be removed before upgrades. The auditor inspects current depth, condition, contamination signs, and air sealing access — and flags vermiculite or settled material that would degrade any new install. See our insulation removal guide for what triggers a removal recommendation.
According to ENERGY STAR's Seal and Insulate program, “EPA estimates that homeowners can save an average of 15% on heating and cooling costs (or an average of 11% on total energy costs) by air sealing their homes and adding insulation in attics, floors over crawl spaces and basements.”
Process
How does the energy audit process work?
Pre-audit interview
Auditor reviews recent utility bills, asks about comfort complaints, identifies known issues, and walks through the home with the homeowner.
Blower-door setup
Calibrated fan is mounted in the primary entry door; the door frame is sealed to the fan housing.
Depressurization test
Home is depressurized to -50 Pascals. Fan-flow measurement (CFM50) is recorded; ACH50 is calculated using the home's conditioned volume.
Infrared thermal scan
During depressurization, an infrared camera identifies cold spots, missing insulation, thermal bridges, and active air-leak paths. Photos are taken for the report.
Combustion safety check
All gas appliances are checked for proper draft and CO production under depressurization. Any spillage or backdrafting is documented.
Report and recommendations
Within 1-2 business days, the homeowner receives a written report with prioritized recommendations, expected cost ranges, and applicable rebate programs.
Optional follow-up
Auditor available to walk through the report, answer questions, and connect the homeowner with crews for the recommended work. Some audits include a post-work re-test for confirmation.
Rebates & credits
What rebates apply to energy audit in Denver?
Xcel rebates part of the audit price as its own measure. Separately, the Whole Home Efficiency Bonus adds a 25% bonus on all standard rebates when three or more measures are installed within two years of enrolling — an audit is not a condition of it, though it is how most homeowners identify which measures to run. Households that qualify should also evaluate Xcel's income-qualified programs. Subsequent insulation, air-sealing, or HVAC work identified by the audit qualifies for the standard Xcel rebate programs.
- Xcel Energy Insulation and Air Sealing Rebate — standard utility rebate for Xcel heating customers, paid by check after application. Work must be completed by a participating contractor, with a blower door test before and after documenting a reduction of at least 20% in CFM50.
- Xcel Whole Home Efficiency (WHE) Bonus — adds a 25% bonus on all standard rebates when three qualifying measures are completed within two years of enrolling.
- Xcel Insulation + Air Sealing Combo Bonus — a bonus when rebate-qualifying air sealing and insulation are installed before a qualifying space-heating heat pump, within two years of each other by invoice dates; the current bonus amount is set out on Xcel's own program pages.
- Xcel's income-qualified programs — eligibility is set out on Xcel's own program pages.
- Power Ahead Colorado (DRCOG) — Denver-region incentive program. Published policy funds heat pump and heat pump water heater incentives; insulation and air sealing are recommended preparation steps, not incentivized measures. Not yet live.
For current Xcel rebate amounts and program rules, see the Xcel Energy insulation and air-sealing rebates program page. For Colorado-program status (including HEAR closure and Power Ahead Colorado launch), see the Colorado Energy Office Home Energy Rebate page. Eligibility may depend on income, program funding levels, and qualifying product specifications.
Service area
Where do you provide energy audit services in the Denver metro?
We connect homeowners with local insulation pros throughout Denver and the surrounding Front Range.
- Lakewood
- Arvada
- Aurora
- Wheat Ridge
- Centennial
- Englewood
- Littleton
- Westminster
- Thornton
- Park Hill
- Washington Park
- Highland
- Golden
- Broomfield
- Northglenn
Related insulation services
Get a quote
Tell Us About Your Home
We've Got It. Here's What Happens Next.
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 — the 2021 IECC sets a ceiling minimum of R-60 in Climate Zone 5 (Table R402.1.3); R-49 qualifies only where uncompressed insulation extends full-height over the top plate at the eaves. (2) Air sealing scope — insulation and air sealing work together; sealing the leaks first is what lets the insulation do its job. If a quote skips both, get another quote. The federal IRA Section 25C tax credit ended December 31, 2025, and Colorado's HEAR single-family program is now closed for both Region 1 (the Front Range) and Region 2. Xcel Energy programs are the ones still paying on Denver-area insulation projects in 2026.
Frequently asked
What do Denver homeowners ask about energy audit?
Should I do energy audit if my home was built after 2010?
Maybe — and a build date on its own does not settle it. Post-2010 Denver homes were built to the code in force the year they went up, not today's: most attics started at R-30 to R-38, against the R-60 ceiling minimum the 2021 IECC now sets for Climate Zone 5, so a newer attic is commonly short of the current figure from day one. Walls at R-21 are a different story and usually fine. Add the 10-15 year mark, when settled batts and unsealed penetrations start showing up, and the gap widens rather than closes. If your bills and your comfort are both fine, energy audit is still a judgment call about where the next dollar does the most — we'll tell you straight when we look at it.
Do you handle new construction insulation in Denver?
We focus on retrofit insulation for existing homes. New construction insulation typically goes through your general contractor or builder, and the process is different — pricing structures, code compliance steps, and project timing all work differently for new builds. If you're working on a new construction project and need an insulation contractor, we can refer you to a partner with new-construction experience. Send us your project details through the form below and note that it's new construction in the message.
How much does a home energy audit cost in Denver?
No primary source publishes a Denver-specific figure, so this site doesn't print one — a standard audit covers blower-door, infrared, combustion-safety, and a written report, with premium diagnostics costing more. Some crews offer the audit free or discounted when bundled with subsequent insulation work.
What does a blower-door test measure?
Total air leakage from the building envelope. The fan depressurizes the home to -50 Pa while measuring the air flow required to maintain that pressure. Result is reported as ACH50 (air changes per hour at 50 Pa) — a normalized leakiness metric. Lower is tighter.
What's a good ACH50 score for a Denver home?
Per the 2021 IECC R402.4.1.2 table, 3 ACH50 is the new-construction target for Climate Zone 5B. Existing Denver homes vary: tight modern builds 4-6 ACH50, mid-century homes 8-12 ACH50, pre-1940 historic homes 15-25+ ACH50. Going under 3 ACH50 in a retrofit is technically possible but rarely cost-effective.
Will the audit damage anything?
No. The blower-door fan creates a -50 Pa pressure differential — meaningful but not destructive. Doors and windows are exposed to roughly the equivalent of a 20-mph wind from inside. Modern, well-maintained homes handle this without issue.
Do I need an audit before insulation work?
Not always. For obvious cases (visible R-11 attic in a 1970s ranch), the prescription is clear without an audit. For complex or expensive work (whole-home retrofits, conditioned-attic conversions, HVAC + envelope packages), an audit usually pays back through better-prioritized recommendations.
Does Xcel require an audit for rebates?
Not for the standard 2026 Xcel Energy Insulation and Air Sealing Rebate, and not for the Whole Home Efficiency Bonus — Xcel's current rebate summary conditions that bonus on installing three or more measures within two years of enrolling, and names no audit. Income-qualified pathways have their own paperwork; confirm those with your participating contractor. The pro on your job confirms requirements against your specific situation.
Will the audit identify problems I can't afford to fix?
Often yes — the audit will list everything worth doing, including expensive items. Reputable auditors order the recommendations by payback so you can address the high-leverage items first. The audit is a roadmap, not an obligation.
Does Xcel rebate the audit cost?
Yes — Xcel rebates part of the audit price, as its own measure rather than as a gate to anything. The Whole Home Efficiency Bonus is separate: it adds a 25% bonus on all standard rebates when three or more measures are installed within two years of enrolling.