What Are The Most Energy Efficient Windows?


Published on July 8, 2014 under Energy Efficiency

Why should you consider replacing your old windows? You look through them every day but do you ever stop to think about the effect your current windows have on the value of your home?

Energy efficiency is one of the top reasons that homeowners choose to install new windows in Maryland. Old windows can contribute to higher heating and cooling costs. It may be more cost effective to replace your old windows rather than try to improve their current efficiency.

Homeowners looking to install higher energy efficient windows should choose ENERGY STAR® qualified products, which ensure you get the best when it comes to energy efficiency. Before choosing your new windows it is important to determine what types of windows will work best with your home.

Energy Efficient Window Ratings

According to Energystar.gov, qualified windows provide performance ratings on these five factors:

  • U-Factor measures the rate of heat transfer and tells you how well the window insulates. U-factor values generally range from 0.25 to 1.25 and are measured in Btu/h•ft²•°F. The lower the U-factor, the better the window insulates.
  • Solar Heat Gain Coefficient (SHGC) measures the fraction of solar energy transmitted and tells you how well the product blocks heat caused by sunlight. SHGC is measured on a scale of 0 to 1; values typically range from 0.25 to 0.80. The lower the SHGC, the less solar heat the window transmits.
  • Visible Transmittance (VT) measures the amount of light the window lets through. VT is measured on a scale of 0 to 1; values generally range from 0.20 to 0.80. The higher the VT, the more light you see.
  • Air Leakage (AL) measures the rate at which air passes through joints in the window. AL is measured in cubic feet of air passing through one square foot of window area per minute. The lower the AL value, the less air leakage. Most industry standards and building codes require an AL of 0.3 cf•m/ft².
  • Condensation Resistance measures how well the window resists water build-up. Condensation Resistance is scored on a scale from 0 to 100. The higher the condensation resistance factor, the less build-up the window allows.

Here is a complete list of ENERGY STAR’s most efficient windows.

How Much Are Your Windows Costing You?

The average home loses 30 perfect of its heat or air-conditioning energy through its windows. Energy efficient windows can save you money every month. There are even some cases where new windows can be net energy gainers. In new homes, higher initial costs can be offset since you could probably install a smaller, less expensive HVAC system. More durable windows can cost less in the long run because of lowered maintenance and replacement costs.

The Importance of Quality Window Installation

Your energy efficient windows are only as good as their installation. Correct installation will:

Protect from water damage. If sealed properly, windows should form a continuous water barrier where they meet the wall. With improper installation, water may get inside, causing damage which is often unseen and behind the wall.

Limit air leaks. Windows should match the wall’s air barrier. If the window is not sealed properly, tiny cracks around the window frame can lead to a considerable heat loss.

Prevent condensation. Windows should compliment the wall’s vapor barrier to prevent water vapor from passing around a window frame. Rot or other damage may occur if vapor condenses on cold surfaces between the window frame and the wall.

Window installations vary depending on the type of window, the structure of the house (wood, masonry, etc.), and what the exterior is made of (wood siding, stucco, brick, etc.).

Investing in Energy Efficient Windows in Maryland

Your home is one of the most valuable investments you will ever make. Replacing your out dated non-efficient windows will add significantly to your investment. You should only have to replace your windows once so make sure you choose the right window and the right installer from the beginning.

Entrust your investment with Potomac View Energy. Let us update your Maryland home with energy efficient windows today. Call us at 410-795-3110!

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