When hiring an energy auditor, you will encounter two main certifications: BPI (Building Performance Institute) and RESNET (Residential Energy Services Network). Understanding the difference helps you choose the right professional for your needs.
BPI Certification
Focus: Existing Home Performance
BPI certification is designed for professionals who assess and improve existing homes. It is the industry standard for residential energy audits and retrofits.
Key Features
- Combustion safety testing: BPI-certified auditors test furnaces, water heaters, and other combustion appliances for carbon monoxide and backdrafting — RESNET does not require this
- Whole-house approach: Evaluates how all systems interact (envelope, HVAC, moisture, safety)
- Multiple specialties: Building Analyst, Envelope Professional, Heating Professional, AC/Heat Pump Professional, Multifamily Building Analyst
- Blower door testing: Required competency for all BPI Building Analysts
2026 Updates
BPI launched updated Energy Auditor Certification exams on February 28, 2026:
- Written exam: 100 multiple choice questions, 75% passing score
- Field exam: 4-hour practical assessment, 83% passing score on remaining tasks
Best For
- Homeowners seeking to improve their existing home's energy efficiency
- Pre-purchase energy evaluations
- Identifying health and safety issues (CO, backdrafting, moisture)
- Qualifying for utility rebate programs (many require BPI-certified auditors)
RESNET HERS Rater Certification
Focus: New Construction and Energy Modeling
RESNET's HERS (Home Energy Rating System) Rater certification focuses on rating homes' energy performance using standardized modeling software.
Key Features
- Energy modeling: Creates a computer model of the home's energy performance
- HERS Index score: Generates a standardized rating (lower = more efficient; 100 = code-built reference home)
- Duct testing: RESNET includes duct leakage testing — BPI does not specifically require it
- Code compliance: Used to demonstrate energy code compliance for new construction
- 40-hour training requirement: Standardized training curriculum
Best For
- New construction energy ratings
- HERS ratings for home sales and green certifications
- Energy code compliance verification
- Building performance benchmarking
- Energy Star, LEED, and green building program compliance
Side-by-Side Comparison
| Feature | BPI | RESNET |
|---|---|---|
| Primary focus | Existing homes | New construction |
| Testing type | Blower door + combustion safety | Blower door + duct testing |
| Energy modeling | Not required | Required |
| Combustion safety | Yes | No |
| Duct leakage testing | Not required | Required |
| Building science fundamentals | Yes | Yes |
| Multiple specialties | Yes (6+ certifications) | No (HERS Rater only) |
| Training hours | No minimum (varies by cert) | 40 hours minimum |
| Continuing education | Required | Required |
| Cost to certify | $500-$2,000 | $1,000-$3,000 |
Which Certification Should You Look For?
Choose BPI When:
- You own an existing home and want to improve energy efficiency
- You are preparing for energy improvements or retrofits
- You want health and safety testing (combustion, CO, moisture)
- Your utility rebate program requires BPI certification
- You want a comprehensive whole-house assessment
Choose RESNET When:
- You are building a new home and need an energy rating
- You need a HERS rating for a home sale
- You need energy code compliance documentation
- You are pursuing Energy Star or green building certification
- You want a standardized energy performance score
Either Works When:
- You want a general understanding of your home's energy performance
- You need a blower door test (both certifications include this)
- You want recommendations for energy improvements
Can One Auditor Hold Both?
Yes, many energy professionals hold both BPI and RESNET certifications. This gives them the broadest skill set for working with both existing and new homes. If you find an auditor with both, you are getting the most versatile professional available.
How to Verify Certifications
BPI
- Visit bpi.org and use the "Find a Pro" tool
- Enter your zip code to find certified professionals near you
- Verify specific certification type and expiration date
RESNET
- Visit resnet.us and use the "Find a Rater" tool
- Search by location or company name
- Verify HERS Rater status and rating provider
Frequently Asked Questions
Does certification guarantee a good auditor?
Certification ensures minimum competency in building science, testing procedures, and safety protocols. However, experience, communication skills, and thoroughness vary. Check reviews, ask for references, and see our guide on how to choose an energy auditor.
Are there other energy auditor certifications?
BPI and RESNET are the only two widely recognized residential energy auditor certifications in the United States (Energy Vanguard, 2024). Some states have their own programs, and utilities may have additional requirements, but BPI and RESNET are the national standards.
How much does a BPI audit cost vs a RESNET rating?
BPI energy audits typically cost $200-$600 for existing homes. RESNET HERS ratings cost $400-$800. The HERS rating is more expensive because it includes computer energy modeling.
Do I need a certified auditor to get utility rebates?
Many utility programs require work to be performed or verified by certified professionals. BPI certification is the most commonly required credential for utility rebate programs. Check your utility's specific requirements.
Which certification is better for finding air leaks?
Both certifications include blower door testing, which is the primary tool for finding air leaks. BPI auditors may also use thermal imaging and smoke pencils during the blower door test. For specifically identifying air leaks, a BPI Building Analyst with thermal imaging equipment is the most thorough option.
-- The Energy Audit Finder Team