How Energy-Efficiency is Replacement Windows

How Energy-Efficiency is Replacement Windows

As energy cost continues to rise, homeowners need better energy conservation to save more. In the US, and major cities around the world, having energy efficient homes couldn’t be more critical than now. Building engineers are finding ways to construct energy-efficient homes and on the menu of energy efficient home materials are replacement windows.

As your new windows age, they become less energy efficient let out about 40% of your home energy. By implication, as your home loses energy, you will spend more to get it back. Beyond the physical cost of restoring your home’s energy, the remote impact of losing energy is even more significant! The health implication of poor interior energy can have dire consequences and surge your health bills. Paying your bills is enough headaches, but when poor health condition sets in, the price is higher.

For Replacement Windows Louisville KY to be energy efficient, the U-factor must be on the lower range of the efficiency reading. Windows u-factor is measured from 0.15 to 0.30; an energy efficient window will be no more than 0.26 for extreme weather prone areas. A window is energy efficient if it sustains indoor energy with high efficiency. If you prefer indoor heat to the spine-chilling cold, it is best to choose replacement windows.

Homes can lose or gain heat in the following ways:

Gains heat

  • Direct Conduction through the windows glass or glazing
  • Windows radiates heat from the sun into the house
  • Radiate heat from interior furniture, walls, and people


Loss heat

  • Expel heat through high range U-factor measure
  • Air leakage through the window frame and old windows or all


The u-factor (energy efficiency rating) of replacement windows is a unity of Btu/hr-ft2-oF which may refer to the glass or glazing of the windows. The ability of the quality of a glazing window to transmit sunlight to the home is as follows:

  • Visible transmittance (VT). This is a fraction of the visible spectrum of the sun, measured as 380 to 720 nanometers. It is weighed by human eye sensitivity transmitted through the glazing of the window. A window with a higher VT sends higher visible lights, which is expressed as a number between 0 and 1. Your home’s daylighting needs will determine the VT you need.


  • Light-to-solar gain (LSG). The SHGC and VT ratio determines the LSG. It is relative efficiency gauge of different glass or glazing daylight transmission while blocking heat gains. A higher number means more light transmission without an increase in heat; although it is rare to have this energy performance rating in replacement windows glasses.


Your type of replacement windows will account for 25% to 30% of heating and cooling energy you use in your home. Higher energy efficient replacement windows can be a good option if your existing windows are costing you more energy loss. Ultimately, when you lose energy, consistently, as a result of poor windows energy retention, you will spend more on your energy bill.


Therefore, to reduce energy bill on heating and cooling your home, think of windows improvement using replacement windows.

Leave a Reply

Your email address will not be published. Required fields are marked *