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-49 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; estimated cost $2,200-$3,800 before rebates." Specific numbers, specific programs, specific paths. 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 the Building Performance Institute, “BPI-certified energy auditors use blower door testing to measure air infiltration in CFM50, with most pre-1990 homes registering 2-4x the leakage of modern construction.”
For broader context, see Energy.gov insulation guidance.
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 eligibility requirement for a rebate program (the 2026 Xcel Whole Home Efficiency Bonus requires a pre-work Xcel-approved audit).
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 a $400 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 (modern code-compliant builds rarely have audit-revealing issues).
Cost & the cost of waiting
How much does energy audit cost in Denver — and what does waiting cost?
Home energy audits in Denver typically run $200-$500 for a standard 2-4 hour assessment with blower-door test, infrared scan, combustion safety check, and written report. Premium audits with extended diagnostics (duct leakage testing, room-by-room pressurization, thorough HVAC analysis) run $500-$900.
Cost drivers and rebate paths: home size (larger homes take longer to audit and price slightly higher); 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); the Xcel-approved audit is approximately 60% rebated by Xcel ($100-$200 back) and serves as the prerequisite for the Whole Home Efficiency Bonus; income-qualified Xcel IQ Program pathways sometimes cover the audit entirely.
Here's the part most quotes won't tell you. 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 — at current Xcel rates that's roughly 18-25% of your winter heating bill walking out the roof. Five winters of waiting is usually more than the project costs once rebates land.
According to the ENERGY STAR, “air sealing alone — before insulation upgrades — can reduce energy bills by up to 15% in older homes.”
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 IECC 2021 R402.1.2 ceiling-insulation table prescribes R-49 minimum (R-60 retrofit target) 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 the Xcel Energy, “Xcel Energy's residential insulation rebate program requires a minimum 20% reduction in air leakage (measured by blower door test) to qualify for full rebate amounts.”
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?
The Xcel-approved energy audit is a prerequisite for the Xcel Whole Home Efficiency Bonus, and the audit itself is approximately 60% rebated by Xcel (typically $100-$200 back). When three or more recommended measures are completed within two years of the audit, the WHE Bonus adds 25% on top of standard insulation and air-sealing rebates. Income-qualified households should also evaluate the Xcel IQ Program. Subsequent insulation, air-sealing, or HVAC work identified by the audit qualifies for the standard Xcel rebate stack.
- Xcel Energy Insulation and Air Sealing Rebate — standard utility rebate, paid as an upfront discount on the invoice when working with a participating Xcel Trades Ally contractor. Air sealing rebates require a blower door pre/post test; air sealing alone does not qualify without insulation.
- Xcel Whole Home Efficiency (WHE) Bonus — adds 25% on top of standard rebates when three or more qualifying measures are completed within two years. Requires an Xcel-approved energy audit (~60% rebated, $100–$200 back) and WHE enrollment.
- Xcel $600 Insulation + Air Sealing Combo Bonus — $600 stacked bonus when air sealing and insulation are completed within two years before a qualifying heat pump install. May sunset April–June 2026 — confirm program status before scoping.
- Xcel IQ Program — income-tiered, four tiers; the lowest tier is geographic-eligibility-based with no income verification, and higher tiers can cover 80–100% of project cost.
- Power Ahead Colorado (DRCOG) — $1,500 rebate, no income limit, Denver metro residents. Launching summer 2026 — not yet live as of May 2026.
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
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We've Got It. Here's What Happens Next.
We've got your info. A local pro is reviewing it now. Expect a call within a few hours, or by tomorrow at the latest. While you wait, here's what to look for in the quote you receive: (1) R-value target — current Colorado code is R-49 to R-60 for attics, anything less is under-spec. (2) Air sealing scope — insulation alone does nothing if air leaks aren't sealed first. (3) Rebate handling — Xcel rebate paperwork should be handled for you, not by you. (The federal IRA Section 25C credit expired in 2025 and Colorado HEAR closed for the Front Range — Xcel programs are now the active rebate stack.) (4) Removal scope — pre-1990 homes often need old insulation removed before new install. If a quote skips all four, get another quote.
Frequently asked
What do Denver homeowners ask about energy audit?
Should I do energy audit if my home was built after 2010?
Probably not yet. Post-2010 homes were built to recent code — most attics started at R-30 to R-38 and walls at R-21. If your bills are normal and your comfort is fine, hold the money. The 10-15 year mark is when settled batts and unsealed penetrations start showing up; that's when energy audit pays back on a newer home. 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?
$200-$500 for a standard audit with blower-door, infrared, combustion-safety, and written report. Premium diagnostics run $500-$900. 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?
For the standard 2026 Xcel Energy Insulation and Air Sealing Rebate, no. For the income-qualified Energy Efficient Plus pathway and certain Whole Home Efficiency Bonus configurations, yes — a pre-work audit is typically required. 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 — the Xcel-approved audit is roughly 60% rebated by Xcel (typically $100-$200 back). The audit is also a prerequisite for the Xcel Whole Home Efficiency Bonus, so the audit cost is essentially paid back via the bonus when three or more recommended measures are completed afterward.