Energy Audits

Homeowner Summary

A home energy audit is a comprehensive assessment of how your home uses (and wastes) energy. A professional auditor uses specialized tools — blower doors, infrared cameras, and duct testers — to pinpoint exactly where conditioned air escapes and where insulation is missing or underperforming. The result is a prioritized list of improvements that can reduce your energy bills by 15-30%.

Most energy audits cost $200 to $600, and many utilities offer them for free or at a steep discount through rebate programs. Some utilities require an audit before approving weatherization or equipment upgrade rebates. The audit typically pays for itself within the first year through identified savings.

The HERS (Home Energy Rating System) rating is the industry standard scoring method. A standard new home scores 100; a net-zero home scores 0. Most existing homes score between 100 and 200. Every 1-point reduction in HERS score corresponds to roughly 1% less energy use compared to a standard new home.

How It Works

A professional energy audit follows a systematic process to evaluate every aspect of your home's energy performance.

Blower door test: A calibrated fan is mounted in an exterior door and depressurizes the home to 50 Pascals (about 0.2 inches of water column). The fan measures how much air leaks in through cracks and gaps, expressed in cubic feet per minute (CFM50). The result is converted to air changes per hour (ACH50). A tight home is under 5 ACH50; a leaky home may exceed 15 ACH50. The auditor then walks through the home feeling for drafts to identify the specific leakage locations.

Thermal imaging: An infrared camera reveals temperature differences in walls, ceilings, and floors. Cold spots in winter (or hot spots in summer) indicate missing insulation, air leaks, or thermal bridging. Thermal imaging works best when there is at least a 15-20 degree F temperature difference between inside and outside.

Duct leakage test: A duct blaster fan pressurizes the duct system to 25 Pascals and measures total leakage in CFM25. Leaky ducts in unconditioned spaces (attics, crawlspaces) can waste 20-30% of heating and cooling energy. Results are compared to the total system airflow to calculate duct leakage as a percentage.

Combustion safety testing: The auditor tests gas appliances for carbon monoxide production, verifies proper drafting of exhaust gases, checks for gas leaks, and ensures that air sealing improvements will not cause backdrafting of combustion appliances.

Insulation assessment: The auditor measures existing insulation levels in the attic (depth and type), checks wall insulation (using infrared or drill-and-probe), and evaluates crawlspace or basement insulation.

Maintenance Guide

DIY (Homeowner)

• Perform a visual self-audit annually: check for obvious gaps around windows, doors, and penetrations
• Use an incense stick on windy days to detect drafts around outlets, windows, and recessed lights
• Monitor monthly energy usage for unexplained increases
• Check attic insulation depth (should be 10-14 inches of fiberglass or 8-12 inches of cellulose for R-38 to R-60)
• Feel for drafts near electrical outlets on exterior walls

Professional

• Every 5 years: Full energy audit with blower door test and thermal imaging to reassess home performance, especially after renovations or HVAC replacement
• After major renovations: Re-test to verify improvements and identify new issues introduced during construction
• Before/after air sealing: Test-in/test-out blower door measurements to quantify improvement and verify combustion safety

Warning Signs

• Energy bills significantly higher than comparable homes in your area
• Rooms that are consistently too hot or too cold despite HVAC running
• Drafts felt near windows, doors, outlets, or recessed lights
• Ice dams forming on the roof in winter (indicates attic air leaks and insulation gaps)
• Excessive dust, especially near return air registers
• Humidity problems (too dry in winter, too humid in summer)
• HVAC system runs constantly without reaching setpoint
• Musty smells from crawlspace or basement (may indicate air leakage pathways)

When to Replace vs Repair

Energy audits are a diagnostic service, not a component. The relevant question is when to re-audit:

Re-audit when:

• More than 5 years have passed since the last audit
• You have completed major air sealing, insulation, or HVAC upgrades and want to verify results
• Energy bills have increased without an obvious explanation
• You are planning a major renovation and want to incorporate energy upgrades
• You are buying or selling a home and need a HERS rating

Skip the audit when:

• The home was audited within the past 2 years and no significant changes have been made
• You already have a clear, unfinished list of improvements from a prior audit

Pro Detail

Specifications & Sizing

| Metric | Target (Climate Zone 4-5) | Concerning Level | |--------|---------------------------|------------------| | ACH50 (blower door) | < 5.0 | > 10.0 | | CFM25 duct leakage (total) | < 8% of system CFM | > 15% | | CFM25 duct leakage (to outside) | < 4% of system CFM | > 8% | | Attic insulation | R-49 to R-60 | < R-19 | | Wall insulation | R-13 to R-21 | None (uninsulated) | | Basement/crawl insulation | R-10 to R-15 | None | | CO in flue gas | < 100 ppm | > 200 ppm (action level) | | HERS rating | < 80 (good existing home) | > 150 |

HERS scoring: Index based on reference home (score 100). Accounts for envelope, HVAC efficiency, duct leakage, air leakage, window performance, and hot water. Lower is better. Each point equals approximately 1% of reference home energy use.

Climate zone considerations: Targets vary significantly by climate zone. Hot-humid climates prioritize moisture management and cooling efficiency. Cold climates prioritize air sealing and insulation. Mixed climates need balanced approaches.

Common Failure Modes

(These are common findings from audits, not failures of the audit itself.)

• Attic bypasses: Gaps around plumbing stacks, wiring penetrations, top plates of interior walls, and recessed lights that allow conditioned air to flow into the attic. The number one air leakage pathway in most homes.
• Duct leakage in unconditioned space: Boot-to-floor connections, branch takeoffs, and return platform leaks in attics and crawlspaces. Often represents the single largest energy waste.
• Missing band joist insulation: The rim/band joist area where the floor framing meets the foundation wall is frequently uninsulated and unsealed, creating a major thermal bypass.
• Recessed light leakage: Older non-IC-rated cans create large holes in the ceiling plane. Even IC-rated cans may leak air if not sealed.
• Whole-house fan bypass: Whole-house fans create a large uninsulated opening in the ceiling that leaks air year-round when not in use.
• Attached garage air leakage: Gaps between the garage and living space allow vehicle exhaust and unconditioned air into the home.

Diagnostic Procedures

1. Pre-audit interview: Review 12 months of utility bills, discuss comfort complaints, identify recent changes, understand homeowner priorities and budget.
2. Visual inspection: Walk exterior and interior noting insulation access points, window types, HVAC equipment, duct routing, and obvious deficiencies.
3. Blower door test: Install fan in primary exterior door. Close all windows and exterior doors. Turn off combustion appliances. Depressurize to -50 Pa. Record CFM50 and calculate ACH50. Walk the home with smoke pencil or hand to locate leaks. Use thermal camera to visualize leakage pathways.
4. Duct leakage test: Seal all registers. Pressurize duct system to 25 Pa using duct blaster. Record total leakage (CFM25 total) and leakage to outside (CFM25 out, measured with house simultaneously pressurized to neutralize envelope leakage).
5. Combustion safety (CAZ test): Test worst-case depressurization of the combustion appliance zone. Run all exhaust fans, dryer, and close interior doors. Check for backdrafting of water heater and furnace. Measure CO in flue gas.
6. Report generation: Compile findings into prioritized recommendation list with estimated costs, savings, and payback periods.

Code & Compliance

• RESNET/HERS: Certified HERS raters follow RESNET standards for testing protocols and scoring. Required for Energy Star certification and many utility programs.
• BPI (Building Performance Institute): BPI-certified auditors follow BPI-1100 and BPI-1200 standards. Required by many weatherization programs.
• IECC (International Energy Conservation Code): Sets baseline energy performance for new construction. Audit findings are often benchmarked against IECC requirements for the applicable climate zone.
• DOE WAP: Department of Energy Weatherization Assistance Program has specific audit protocols (NEAT/MHEA) for income-qualified programs.
• Combustion safety: BPI requires worst-case CAZ testing before and after air sealing work. Must verify that tightening the envelope does not cause combustion appliance backdrafting.
• State programs: Many states have specific certifications (e.g., California HERS, Massachusetts HERS) with additional testing requirements.

Cost Guide

| Service | Typical Cost | Notes | |---------|-------------|-------| | Basic energy audit | $200-$400 | Visual inspection + blower door + recommendations | | Comprehensive audit (HERS rating) | $400-$600 | Full diagnostic including duct testing, thermal imaging | | Utility-subsidized audit | $0-$100 | Many utilities cover 50-100% of audit cost | | Blower door test only | $150-$300 | Standalone test without full audit | | Duct leakage test only | $150-$250 | Standalone duct blaster test | | Thermal imaging scan | $100-$300 | Often included in comprehensive audit | | Post-improvement verification | $150-$300 | Test-out blower door after air sealing work | | HERS rating (new construction) | $300-$500 | Required for Energy Star certification |

Rebate programs: Most major utilities offer energy audit rebates. Common structures include free audits for income-qualified households, $200-$400 rebates toward audit cost, or free audits that unlock access to weatherization rebate programs. Check DSIRE (Database of State Incentives for Renewables and Efficiency) for local programs. The Inflation Reduction Act (IRA) provides up to $150 in tax credits for home energy audits (Section 25C).

Energy Impact

A comprehensive energy audit typically identifies improvements that can reduce total energy consumption by 15-30%. The most impactful findings, in typical priority order:

1. Air sealing (5-15% reduction): Sealing attic bypasses, rim joists, and major penetrations. Often the highest ROI improvement.
2. Duct sealing (5-10% reduction): Sealing duct leaks in unconditioned spaces. Improves both efficiency and comfort.
3. Insulation upgrades (5-15% reduction): Adding attic insulation to current code levels, insulating rim joists, and addressing wall insulation where feasible.
4. HVAC upgrades (10-30% reduction): Replacing aged equipment with high-efficiency models, properly sized for the improved envelope.
5. Window upgrades (3-8% reduction): Replacing single-pane or failed double-pane windows. Lower ROI than air sealing and insulation.

Typical annual savings: $200-$800 per year depending on current home condition, climate, and energy prices. Air sealing and insulation improvements typically pay back in 2-5 years.

Shipshape Integration

Energy usage monitoring: Shipshape tracks utility consumption data (via utility API integrations or smart meter connections) and identifies usage patterns that suggest audit-worthy issues — sudden increases, unusually high baseline loads, or heating/cooling costs exceeding regional benchmarks.

Efficiency scoring: The Home Health Score includes an Energy Efficiency subscore based on available data: HVAC age and efficiency ratings, insulation levels (from audit data or property records), window types, and historical energy consumption patterns. The score provides a quick snapshot of audit urgency.

Audit recommendation triggers: SAM recommends an energy audit when energy costs exceed comparable homes by 20%+, when the home has no audit on record and is older than 20 years, or when a major renovation is planned.

Audit data integration: When an energy audit is completed, the dealer enters key findings (ACH50, HERS score, insulation levels, duct leakage) into Shipshape. This data updates the home profile and refines the Energy Efficiency score.

Improvement tracking: As audit recommendations are completed (air sealing, insulation, duct sealing), Shipshape tracks the before/after energy consumption to quantify actual savings vs projected savings.

Cost tracking: Audit costs, improvement costs, and resulting savings are tracked on the home dashboard. Homeowners see cumulative ROI for energy improvements.

Dealer actions: Service providers receive work orders for recommended improvements prioritized by ROI. Shipshape provides cost estimates and rebate eligibility information to streamline the sales conversation.