audit-home-energy-efficiency

Audit Home Energy Efficiency

Systematically evaluate a home's energy performance and produce a prioritized upgrade roadmap with payback estimates.

Why This Is Best Practice

Adopted by: DOE, ENERGY STAR program partners, RESNET-certified raters, utility companies in 50 states Impact: Homes audited and upgraded per DOE methodology reduce energy bills by 15–30%; proper air sealing alone saves average $300/year; HERS-rated homes sell for 2.7% premium Why best: Systematic assessment catches the highest-ROI improvements (air sealing, insulation) that owners miss when focusing on visible upgrades like new windows

Sources: DOE Home Energy Score Methodology (2023); ENERGY STAR Home Energy Audit Standards (2023); RESNET HERS Index (2023)

Steps

1. Gather 12 months of utility data — Collect electricity and gas bills; calculate energy use intensity (EUI = total BTU / conditioned sq ft). Establish baseline before any changes.

2. Conduct a visual envelope inspection — Inspect attic insulation depth (R-value), wall insulation type, basement/crawlspace conditions, window age and glazing type, and door weatherstripping.

3. Perform blower door test (or estimate air leakage) — A certified rater uses a blower door to measure ACH50 (air changes per hour at 50 pascals). Target: <7 ACH50 for existing homes, <3 for new construction. Without equipment, check for drafts at outlets, switches, and penetrations.

4. Inspect HVAC system — Note equipment age, SEER/AFUE ratings, filter condition, duct location (conditioned vs. unconditioned space), and duct sealing quality. Check thermostat type.

5. Assess water heating — Record water heater age, fuel type, and EF/UEF rating. Check pipe insulation on first 6 feet of hot and cold lines.

6. Evaluate lighting and appliances — Inventory incandescent vs. LED fixtures; note major appliance energy ratings (refrigerator, washer/dryer, dishwasher).

7. Calculate HERS index score — Use RESNET methodology or a certified rater: 100 = 2006 IECC reference home; 0 = net-zero. Scores below 70 indicate significant upgrade opportunity.

8. Prioritize by payback period — Rank improvements: air sealing (1–3 yr payback), attic insulation (3–7 yr), HVAC replacement (7–12 yr), windows (15–25 yr). Lead with highest ROI.

9. Identify available incentives — Check federal tax credits (IRA 2022: up to $3,200/yr for efficiency upgrades), state rebates, and utility programs. Incentives can cut payback periods by 30–50%.

10. Produce written audit report — Document findings, recommended measures, estimated costs, annual savings, simple payback, and incentive eligibility for each measure.

Rules

• Always establish a pre-retrofit energy baseline before recommending improvements.
• Never recommend window replacement before addressing air sealing and insulation — windows have the worst payback of common upgrades.
• Combustion safety testing (CO and spillage) must accompany any air-sealing work in homes with gas appliances.
• Report HERS index relative to local climate zone for accurate benchmarking.

Common Mistakes

• Replacing windows first — costs $10,000–$20,000 with 20+ year payback while air sealing costs $500–$2,000 with 1–3 year payback.
• Ignoring duct leakage — ducts in unconditioned attics can lose 20–30% of conditioned air; duct sealing often has better ROI than equipment upgrades.
• Oversizing replacement HVAC — bigger is not better; oversized systems short-cycle, reduce comfort, and increase humidity. Use Manual J load calculation.
• Missing combustion safety — tightening a home with gas appliances without testing can cause backdrafting and CO poisoning risk.

When NOT to Use

• When a certified energy auditor has already produced a recent report (within 2 years)
• When the home is already net-zero or HERS-rated below 50
• When the goal is purely cosmetic renovation with no systems changes