Energy Efficiency Guides & Calculators
33 expert guides covering SEER2, AFUE, HSPF2 ratings, tax credits, energy costs, and savings calculators
2026 Efficiency Standards
SEER2 Minimums
Southeast & Southwest regions
HSPF2 Minimums
Heat pump heating efficiency
AFUE Minimums
Gas furnace efficiency
EER2 Minimums
Peak cooling efficiency
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Energy Costs & Savings
Electricity costs by state and energy consumption analysis
Average Electric Bill by State: Monthly + Annual Costs (2026 Data)
The average US electric bill is $149/month in 2026. See all 50 states ranked by monthly and annual electric bills, with breakdowns by season, home type, and tips for reducing yours.
Electric Water Heating Cost by State: 2026 RECS Data Analysis
Electric water heaters cost $468/year on average nationally, but range from $294 in Idaho to $1,170 in Hawaii. See costs for all 50 states with analysis of tank vs. heat pump vs. tankless options.
Electricity Cost by State: 2026 Rates Ranked (All 50 States)
Average residential electricity rates for all 50 states in 2026, ranked from cheapest to most expensive. Idaho leads at 10.5c/kWh while Hawaii tops out at 42.1c/kWh. See rate trends, causes, and HVAC cost impacts.
Home Energy Costs: Complete Guide to Reducing Your Bills in 2026
The average US household spends $2,868/year on energy. Learn exactly where your money goes, which upgrades deliver the fastest payback, and how to cut your bills by 25-50% with proven strategies.
DIY Home Energy Audit: Find Where You're Wasting Money (2026 Guide)
A DIY home energy audit can reveal $200-$800/year in energy waste. Follow this room-by-room checklist to find air leaks, insulation gaps, HVAC problems, and phantom loads without hiring a professional.
How Many kWh Per Day Is Normal? (US Average + By State Data for 2026)
The average US household uses 29.1 kWh per day (886 kWh/month). See how your usage compares by state, home size, climate zone, and household type with real EIA RECS data.
How to Read Your Electric Meter (Digital + Analog Guide for 2026)
Learn to read digital, smart, and analog electric meters step-by-step. Track daily kWh usage, verify your utility bill accuracy, and spot energy waste by monitoring your meter readings.
kWh Cost Calculator: Convert kWh to Dollars Instantly (2026 Rates)
Calculate your electricity cost per kWh, daily, monthly, and annual. Use real 2026 rates by state. The average US residential rate is 16.8¢/kWh — find yours and see exactly what your appliances cost to run.
Specific Heat Capacity Calculator: Formula, Examples & HVAC Applications (2026)
Calculate specific heat capacity, energy transfer, and temperature change for any material. Includes the Q = mcΔT formula with step-by-step examples for water heating, HVAC system sizing, and thermal storage.
Time-of-Use Electricity Rates Explained: Save 15-25% on Your Bill (2026)
Time-of-use (TOU) rates charge less for electricity during off-peak hours and more during peak demand. Learn how TOU plans work, whether one saves you money, and strategies to maximize off-peak savings.
Energy Efficiency Ratings
SEER2, AFUE, HSPF2, EER2 ratings and efficiency standards explained
AFUE Rating for Furnaces: How to Calculate AFUE Savings
AFUE (Annual Fuel Utilization Efficiency) measures what percentage of fuel your furnace converts into usable heat. Learn AFUE ratings for gas, oil, and electric furnaces, calculate your potential savings, and find the right efficiency level for your home.
CADR Rating Explained: How to Choose an Air Purifier by CADR
CADR (Clean Air Delivery Rate) measures how many cubic feet of clean air a purifier delivers per minute for smoke, dust, and pollen. Learn how to match CADR to room size, what good CADR looks like, and how to compare purifiers.
CEER Rating Explained: Combined EER for Window ACs
CEER (Combined Energy Efficiency Ratio) is the efficiency rating for window and portable air conditioners that includes standby power consumption. Learn what CEER means, good ratings by size, and how to compare window AC units.
COP Explained: Coefficient of Performance of Heat Pumps
COP (Coefficient of Performance) measures heat pump efficiency as the ratio of heat output to electrical input. A COP of 3.0 means 3 kWh of heat per 1 kWh of electricity. Learn COP ranges, how COP changes with temperature, and how to compare COP across heat pump types.
EER Chart for Air Conditioners (Good, Average, Excellent)
Reference EER and EER2 charts for central ACs, window units, mini-splits, and portable ACs. Find where your unit ranks and what constitutes a good, average, or excellent EER for each equipment type.
What Is EER Rating? Energy Efficiency Ratio Explained
EER (Energy Efficiency Ratio) measures how efficiently an air conditioner cools at peak outdoor temperature (95F). Learn the EER formula, how it differs from SEER, typical EER ranges, and when EER matters more than other ratings.
EER vs SEER: What's the Difference Between These Ratings?
EER measures AC efficiency at peak conditions (95F), while SEER averages over an entire cooling season. Learn when each matters, how they relate, and which to prioritize for your climate and usage.
Understanding EER2: The New 2023 AC Efficiency Rating
EER2 measures your AC's cooling efficiency at peak conditions (95F outdoor). Learn what EER2 means, how it differs from SEER2, current minimums, and why EER2 matters in hot climates.
ESEER Explained: European Seasonal Energy Efficiency Ratio
ESEER (European Seasonal Energy Efficiency Ratio) measures cooling efficiency for commercial HVAC in Europe using four part-load conditions. Learn how ESEER compares to SEER, IEER, and when it applies.
What Is a Good SEER Rating? (2026 Buying Guide)
A good SEER rating for an air conditioner in 2026 is 16–18 SEER2 for most homeowners. Learn how to choose the right SEER rating for your climate, budget, and home size with data-backed recommendations and cost comparisons.
How To Calculate SEER Rating (Formula + Examples)
Learn the SEER and SEER2 formulas with step-by-step examples. Calculate your AC's efficiency, estimate annual energy costs, and compare units using real math.
HSPF Rating: What Is a Good HSPF for Heat Pumps?
HSPF (Heating Seasonal Performance Factor) measures heat pump heating efficiency over a full winter season. Learn what HSPF means, good vs excellent ranges, how it compares to HSPF2, and how to use HSPF when evaluating heat pumps.
Understanding HSPF2: Heat Pump Heating Efficiency Rating
HSPF2 (Heating Seasonal Performance Factor 2) measures how efficiently a heat pump heats your home over an entire winter season. Learn what HSPF2 means, good vs excellent ratings, how it compares to HSPF, and why it matters for your energy bills.
All HVAC Efficiency Ratings Compared (SEER2, EER2, HSPF2, COP, AFUE)
A complete comparison of every HVAC efficiency rating: SEER2, EER2, HSPF2, COP, AFUE, IEER, CEER, CADR, and MERV. Learn what each measures, when it matters, how to convert between them, and which ones to prioritize when shopping.
IEER Explained: Integrated Energy Efficiency Ratio
IEER measures commercial air conditioning efficiency across four part-load conditions. Learn the IEER formula, how it compares to EER, when it applies, and what constitutes a good IEER for commercial HVAC systems.
MERV Rating Chart: What MERV Filter Do You Need?
MERV ratings range from 1 to 20, measuring how well an air filter captures particles. Most homes need MERV 8-13. See the complete MERV chart with particle sizes, applications, costs, and airflow impact.
Minimum SEER Rating by State in 2026 (SEER2 Requirements Map)
Find your state's minimum SEER2 rating requirement for 2026. The DOE divides the U.S. into three regions with different AC and heat pump efficiency minimums. See the complete state-by-state list with SEER2 and HSPF2 minimums.
SEER Rating Requirements for Federal Tax Credits (2026)
To claim the federal 25C energy efficiency tax credit in 2026, your AC needs 17.5+ SEER2 and heat pumps need specific SEER2/HSPF2 thresholds. Learn exact requirements, credit amounts ($600 AC / $2,000 heat pump), and how to qualify.
SEER vs SEER2: What Changed and Why It Matters
SEER2 replaced SEER on January 1, 2023, using a tougher M1 test with higher static pressure. Learn exactly what changed, how to convert between the two standards, and what the new minimums mean for your AC purchase.
Understanding SEER2: Complete Guide to the New AC Efficiency Rating
SEER2 is the updated air conditioner efficiency standard effective January 2023. Learn what SEER2 means, how it differs from SEER, new minimum requirements by region, and how to use SEER2 to compare AC units and save on energy costs.
SEER2 Savings Calculator: Compare AC Running Costs
Use our SEER2 savings calculator to compare annual cooling costs between air conditioners at different SEER2 ratings. Enter your system size, electricity rate, and cooling hours to see exact dollar savings and payback periods.
SEER2 to SEER Conversion: Calculator + Equivalency Chart
Convert between SEER2 and SEER ratings with our calculator and comprehensive equivalency chart. Includes EER-to-EER2 and HSPF-to-HSPF2 conversions with step-by-step examples.
What Is SEER Rating? How AC Energy Efficiency Is Measured
SEER (Seasonal Energy Efficiency Ratio) measures how efficiently an air conditioner cools your home over a full season. Learn the SEER formula, what the numbers mean, and how SEER compares to the new SEER2 standard.
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Home Energy Costs: Complete Guide to Reducing Your Bills in 2026
The average US household spends $2,868/year on energy. Learn exactly where your money goes, which upgrades deliver the fastest payback, and how to cut your bills by 25-50% with proven strategies.
kWh Cost Calculator: Convert kWh to Dollars Instantly (2026 Rates)
Calculate your electricity cost per kWh, daily, monthly, and annual. Use real 2026 rates by state. The average US residential rate is 16.8¢/kWh — find yours and see exactly what your appliances cost to run.
AFUE Rating for Furnaces: How to Calculate AFUE Savings
AFUE (Annual Fuel Utilization Efficiency) measures what percentage of fuel your furnace converts into usable heat. Learn AFUE ratings for gas, oil, and electric furnaces, calculate your potential savings, and find the right efficiency level for your home.
CADR Rating Explained: How to Choose an Air Purifier by CADR
CADR (Clean Air Delivery Rate) measures how many cubic feet of clean air a purifier delivers per minute for smoke, dust, and pollen. Learn how to match CADR to room size, what good CADR looks like, and how to compare purifiers.
COP Explained: Coefficient of Performance of Heat Pumps
COP (Coefficient of Performance) measures heat pump efficiency as the ratio of heat output to electrical input. A COP of 3.0 means 3 kWh of heat per 1 kWh of electricity. Learn COP ranges, how COP changes with temperature, and how to compare COP across heat pump types.
Understanding EER2: The New 2023 AC Efficiency Rating
EER2 measures your AC's cooling efficiency at peak conditions (95F outdoor). Learn what EER2 means, how it differs from SEER2, current minimums, and why EER2 matters in hot climates.