Frequently Asked Questions - Abbreviations and Definitions

Energy Factor, or EF, is the energy performance metric used for electric water heaters. The higher the EF, the more efficient the electric water heater. To look up your electric water heater’s EF, visit the ENERGY STAR® website.

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A device that uses a small amount of energy to heat your home, unlike gas furnaces they also have the ability to provide cooling when needed.

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Heating Seasonal Performance Factor, is an equipment efficiency rating. HSPF is a measure of a heat pump's energy efficiency over one heating season. It represents the total heating output of a heat pump (including supplementary back-up electric heat) during the normal heating season.

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Modified Energy Factor, or MEF, is a calculation used to compare the relative efficiency of different clothes washers. The higher the value, the more efficient the clothes washer. To find your clothes washer's MEF, go to the ENERGY STAR® website.

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The National Fenestration Rating Council (NFRC) is a 501(c)3, non-profit organization which provides performance ratings on windows, doors, and skylights. NFRC administers a certification and labeling program overseeing energy-efficiency of windows, doors, and skylights.

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R-value of insulation is a measurement of the insulation's ability to resist heat traveling through it. The higher the R-value the more effective your insulation is at regulating the temperature inside your home.

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Seasonal Energy Efficiency Ratio, an equipment efficiency rating that measures how much energy it takes to cool the air. It measures how efficiently a cooling system will operate over an entire season. The higher the SEER, the more efficient the air conditioner.

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Solar Heat Gain Coefficient is the fraction of solar radiation admitted through a window. This tells you how well the product blocks heat caused from the sun. The lower SHGC, the less solar heat it admits into your home.

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U-Factor measures the heat transfer through a window and lets you know how well the product insulates. The lower the U-Factor, the greater resistance to heat flow (in and out) and the better its insulation value.

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Water Factor, or WF, is the water performance metric that allows the comparison of clothes washer water consumption independent of clothes washer capacity. The lower the value, the more water efficient the clothes washer is. To find your clothes washer's WF, go to the ENERGY STAR® website.

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Home Energy Savings is under Pacific Power's wattsmart Homes program which offers incentives and services for residential energy efficiency projects.

Home Energy Savings is under Rocky Mountain Power's wattsmart Homes program which offers incentives and services for residential energy efficiency projects.