HERS Rating Calculator
Calculate your home’s energy efficiency score and potential savings with our accurate HERS Index tool.
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Complete Guide to Understanding HERS Ratings
The Home Energy Rating System (HERS) Index is the industry standard for measuring a home’s energy efficiency. Developed by the Residential Energy Services Network (RESNET), the HERS Index provides homeowners with a reliable way to understand their home’s energy performance and identify opportunities for improvement.
What is a HERS Rating?
A HERS rating is a standardized measurement of a home’s energy efficiency. The lower the score, the more energy efficient the home:
- HERS 0: Net-zero energy home (produces as much energy as it consumes)
- HERS 50: 50% more efficient than a standard new home
- HERS 100: Standard new home built to code
- HERS 130: Typical resale home
- HERS 150+: Older, less efficient homes
How HERS Ratings Are Calculated
A certified RESNET HERS Rater performs a detailed analysis of your home, including:
- Building envelope: Walls, roof, foundation, windows, and doors
- HVAC systems: Heating, cooling, and ventilation equipment
- Water heating: Type, efficiency, and distribution system
- Appliances: Energy consumption of major appliances
- Lighting: Type and quantity of lighting fixtures
- Air leakage: Blower door test to measure air infiltration
- Thermal boundaries: Insulation levels and quality
Benefits of a Low HERS Score
- Lower energy bills: Homes with HERS scores below 70 typically save 30% or more on energy costs
- Increased comfort: Better insulation and air sealing eliminate drafts and temperature variations
- Higher resale value: Energy-efficient homes command premium prices in the real estate market
- Environmental impact: Reduced energy consumption lowers your carbon footprint
- Mortgage benefits: Some lenders offer “energy-efficient mortgages” with better terms for low-HERS homes
Common HERS Score Ranges
| HERS Score Range | Home Type | Energy Use vs. Standard |
|---|---|---|
| 0-30 | Net-zero or near net-zero | 70-100% more efficient |
| 31-50 | Super-efficient | 50-70% more efficient |
| 51-70 | Highly efficient | 30-50% more efficient |
| 71-100 | Above average | 0-30% more efficient |
| 101-130 | Average | Standard efficiency |
| 131+ | Below average | Less efficient than standard |
How to Improve Your HERS Score
Improving your home’s HERS score requires a systematic approach to energy efficiency. Here are the most impactful upgrades, ranked by cost-effectiveness:
1. Air Sealing and Insulation
The building envelope is typically the largest source of energy loss in homes. According to the U.S. Department of Energy, proper air sealing and insulation can reduce energy costs by 10-20%.
- Attic insulation: Upgrade to R-38 to R-60 (12-20 inches)
- Wall insulation: Add blown-in cellulose or fiberglass to existing walls
- Basement/crawlspace: Insulate rim joists and foundation walls
- Air sealing: Seal gaps around windows, doors, electrical outlets, and plumbing penetrations
2. High-Performance Windows
Windows account for 25-30% of residential heating and cooling energy use. The ENERGY STAR program reports that replacing single-pane windows with ENERGY STAR certified models can save $101-$583 annually.
| Window Type | U-Factor | Solar Heat Gain Coefficient | Potential Savings vs. Single-Pane |
|---|---|---|---|
| Single-pane | 1.20 | 0.85 | Baseline |
| Double-pane (standard) | 0.50 | 0.70 | 10-20% |
| Double-pane Low-E | 0.30 | 0.40 | 20-30% |
| Triple-pane | 0.20 | 0.30 | 30-40% |
3. HVAC System Upgrades
Heating and cooling account for about 50% of home energy use. The U.S. Department of Energy recommends:
- Heat pumps: Can reduce electricity use for heating by 50% compared to electric resistance heating
- High-efficiency furnaces: 95%+ AFUE models save 15-20% over 80% AFUE units
- Smart thermostats: Can save about 8% on heating and cooling bills
- Duct sealing: Can improve efficiency by 20% or more in homes with leaky ducts
HERS Ratings and Home Value
Energy efficiency is increasingly important in the real estate market. A study by the National Renewable Energy Laboratory (NREL) found that:
- Homes with HERS scores below 70 sell for 3-5% more than comparable homes
- For every 1-point decrease in HERS score, home value increases by approximately $100-$200
- Energy-efficient homes spend 13% less time on the market
- Appraisers are increasingly incorporating energy efficiency into home valuations
HERS Ratings and Mortgages
Several mortgage programs offer benefits for energy-efficient homes:
- Energy Efficient Mortgage (EEM): Allows borrowers to finance energy improvements into their primary mortgage
- FHA EEM: Insured by the Federal Housing Administration, allows up to 5% of home value for improvements
- VA EEM: For veterans, allows up to $6,000 for energy improvements without affecting loan limits
- Conventional EEM: Offered by Fannie Mae and Freddie Mac, allows 10-15% of appraised value for improvements
HERS Ratings vs. Other Energy Standards
HERS vs. ENERGY STAR
While both measure energy efficiency, they serve different purposes:
- HERS Index: Precise numerical score (0-150+) that measures relative efficiency
- ENERGY STAR: Binary certification (meets standards or doesn’t) based on HERS score thresholds
- HERS 70 or lower: Typically qualifies for ENERGY STAR certification
- HERS 50 or lower: Qualifies for ENERGY STAR Most Efficient designation
HERS vs. LEED for Homes
LEED (Leadership in Energy and Environmental Design) is a broader sustainability certification:
- HERS: Focuses solely on energy efficiency
- LEED: Considers energy, water, materials, indoor air quality, and site selection
- HERS score: Required for LEED energy performance points
- LEED certification: Requires HERS score of 60 or lower for most points
Frequently Asked Questions About HERS Ratings
How much does a HERS rating cost?
The cost of a professional HERS rating typically ranges from $300 to $800, depending on:
- Home size and complexity
- Local market rates
- Whether it’s part of new construction or an existing home
- Additional services like blower door tests or duct leakage tests
How long does a HERS rating last?
A HERS rating is valid as long as no significant changes are made to the home’s energy-related systems. However:
- For new construction, the rating is typically valid for the life of the home unless major renovations occur
- For existing homes, recertification is recommended after major upgrades (e.g., new HVAC system, window replacement)
- Some utility programs require ratings to be less than 2-3 years old for rebates
Can I get a HERS rating for an apartment or condo?
Yes, but the process differs slightly:
- Individual units: Can be rated if they have dedicated HVAC systems and separate thermal boundaries
- Whole buildings: Multifamily buildings can get a “HERS for Multifamily” rating
- Shared systems: May require special calculations for common area energy use
How accurate are online HERS calculators?
While online tools like this one provide useful estimates, they have limitations:
- Pros: Quick, free, good for initial planning
- Cons: Less accurate than professional ratings, don’t account for all variables
- Accuracy: Typically within ±10-15 points of a professional rating
- For official use: Always get a certified HERS rater for mortgages, rebates, or certifications