What Is the Best Energy-Efficient Window Type for Hot Climates?

hands pushing down a window

With the best energy efficient window, you can control the temperature within your home and make the space cooler during hot summer days. The right windows will allow sunlight to pass through, but block heat, helping you save both energy and money on air conditioning. Follow the tips below when choosing the type of energy efficient windows that work best in hot climates.

Selecting Window Frames

The type of window frames you use will have a great impact on the energy efficiency of your windows. Frames may be made of several different materials, including aluminum, fiberglass, vinyl, and wood. Aluminum frames, though widely used in modern construction, are the least energy efficient. Fiberglass frames are moderately efficient. Wood and vinyl frames are highly efficient. Wood frames are costlier while vinyl frames are affordable.

Window Glasses for Energy Efficiency

The glass panels contribute to the energy efficiency of a window. There are three factors to consider for the types of glass: visible transmission (VT); solar heat gain coefficient (SHGC); and u-value.

VT is the amount of sunlight that is transmitted through the glass, while SHGC is the fraction of total solar heat that can pass through the glass. U-Value is a measure of the transfer of heat through the glass through conduction, convection, and radiation.

Glasses with high VT allow significant daylight into the house thereby reducing the necessity of lights during daytime and hence help in saving energy. The recommended value for VT is 60 to 80%. For hot climates SHGC should be as low as possible. Glasses with low SHGC let a lesser fraction of solar heat into the house and thus help in saving the air-conditioning bills. SHGC of below 0.40 is recommended for places with hot climates. The glasses with low u-value is recommended for all climates.

Use of Multi-Pane Glasses

Single pane glasses are highly inefficient and no longer used. Using a double- or triple-pane glass is recommended for energy efficiency. The vacuum created between different panes of multi-pane windows is what causes insulation and hence helps in saving energy.

For best energy efficiency, there has to be a perfect vacuum between panes and that is possible if the glasses are very thick. Various gases are used between panes to create insulation. These gases are better insulators than air and help conserve energy.

Argon is most commonly used due to its efficiency and affordability. Krypton is used for special glasses which are very thin while xenon is rarely used due to its high cost.

Low Emissive Glasses

Low emissive glass panes are also used to improve energy efficiency. Low emissivity glass has a coating of a metallic oxide layer on the inner side. The low emissive coating prevents heat transfer between panes i.e. from a glass of high temperature to the glass of lower temperature. For places with hot climates, the low-e coating needs to be applied to the inner side of the outermost pane. Low solar gain low emissive glasses reduce the incoming heat and form the best energy-efficient windows for hot climates.

While purchasing and selecting windows, look for NFRC ratings.