Energy Efficiency Guides & Calculators
In-depth 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
Heating Cost Calculator: Compare Gas vs Electric vs Heat Pump Costs
Compare what it costs to heat the same home with gas, a heat pump, pellets, oil, propane or electric resistance, per million BTU and per year, with a calculator for your home.
How Many kWh Per Day Is Normal? (US Average + By State Data for 2026)
The average US household uses about 28.4 kWh per day (about 863 kWh/month, 10,356/year) per EIA 2024 data. See how your usage compares by state, home size, household size, and heating fuel.
How to Read Your Electric Meter (Digital + Analog Guide for 2026)
How to read smart, digital and dial electric meters, track your daily usage, check your bill against the meter, and read a net meter with solar panels.
kWh Cost Calculator: Convert kWh to Dollars Instantly (2026 Rates)
Convert kWh to dollars at your rate. Residential electricity prices for every state from the EIA (January to July 2026), bill estimates and appliance running costs.
Specific Heat Capacity Calculator: Q = mcΔT for Water, Air and Materials (2026)
Calculate the energy to heat or cool any material with Q = mcΔT, with specific heats for water, air, metals and building materials, worked HVAC examples, and what they cost in electricity.
Energy Efficiency Ratings
SEER2, AFUE, HSPF2, EER2 ratings and efficiency standards explained
HVAC Energy Saving Tips: 14 Ways to Cut Heating and Cooling Costs (2026)
Fourteen ways to cut heating and cooling costs, each backed by DOE or ENERGY STAR figures: thermostat setbacks, air and duct sealing, filters, fans, windows, insulation, maintenance and replacement.
AFUE Rating for Furnaces: How to Calculate AFUE Savings
What AFUE measures, condensing vs. non-condensing furnaces, what each rating costs to run on the shared heat-loss model, payback on the price difference, and the 2028 federal minimum.
COP Explained: Coefficient of Performance of Heat Pumps
What a heat pump's COP means, how it changes with outdoor temperature, how it relates to HSPF2, SEER2 and EER2, the physical limit, and what COP means for your heating bill.
EER Chart for Air Conditioners (Good, Average, Excellent)
What EER and EER2 mean, a chart of watts per ton and hourly running cost at every EER, where central, window, mini split and portable ratings differ, and where your unit falls.
HSPF and HSPF2 Explained: Heat Pump Heating Efficiency (2026)
What HSPF2 measures, how it relates to the old HSPF and to COP, the federal and ENERGY STAR minimums, what each rating costs to heat a home, and why cold climates need more than the number.
MERV Rating Chart: What MERV Filter Do You Need?
MERV ratings run 1 to 16 for homes, measuring how well an air filter captures particles by size. Most homes need MERV 8-13. See the complete chart verified against ASHRAE Standard 52.2, with what each level captures and the real airflow trade-off.
Minimum SEER Rating by State in 2026 (SEER2 Requirements Map)
Find your state's minimum SEER2 requirement. The DOE divides the U.S. into three regions with different AC minimums (13.4 North; 14.3 South/Southwest), while heat pumps are a single national 14.3 SEER2 / 7.5 HSPF2. Full state list included.
SEER2 Explained: What the AC Efficiency Rating Means (2026)
What SEER2 measures, why it replaced SEER, the federal minimums by region, what counts as a good rating, running costs, and when a higher rating pays back.
SEER2 to SEER Conversion: Chart and Formula (2026)
Convert SEER to SEER2 and HSPF to HSPF2 with the approximate factors, the DOE's official equivalent minimums, a conversion chart, and why the new ratings read lower.
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kWh Cost Calculator: Convert kWh to Dollars Instantly (2026 Rates)
Convert kWh to dollars at your rate. Residential electricity prices for every state from the EIA (January to July 2026), bill estimates and appliance running costs.
AFUE Rating for Furnaces: How to Calculate AFUE Savings
What AFUE measures, condensing vs. non-condensing furnaces, what each rating costs to run on the shared heat-loss model, payback on the price difference, and the 2028 federal minimum.
COP Explained: Coefficient of Performance of Heat Pumps
What a heat pump's COP means, how it changes with outdoor temperature, how it relates to HSPF2, SEER2 and EER2, the physical limit, and what COP means for your heating bill.
MERV Rating Chart: What MERV Filter Do You Need?
MERV ratings run 1 to 16 for homes, measuring how well an air filter captures particles by size. Most homes need MERV 8-13. See the complete chart verified against ASHRAE Standard 52.2, with what each level captures and the real airflow trade-off.
Minimum SEER Rating by State in 2026 (SEER2 Requirements Map)
Find your state's minimum SEER2 requirement. The DOE divides the U.S. into three regions with different AC minimums (13.4 North; 14.3 South/Southwest), while heat pumps are a single national 14.3 SEER2 / 7.5 HSPF2. Full state list included.
SEER2 Explained: What the AC Efficiency Rating Means (2026)
What SEER2 measures, why it replaced SEER, the federal minimums by region, what counts as a good rating, running costs, and when a higher rating pays back.