Kehl Windows and Doors
Kehl Windows and Doors
When you buy from Kehl, you buy directly from the factory.

How Important is Window Insulation?

ENERGY STAR, R Value, U Value, Solar Heat Gain Coefficient - insulation is essential. Insulation ensures your window is operating at its best performance. It helps reduce energy consumption (and energy bills), improves air quality and increases comfort on a daily basis.

The R-Value is the resistance of a given material to thermal transmission. The higher it is, the better. The insulation specialist will often refer to the R-value and how it is an important number. Please note that a typical wall gets a R-25 rating, whereas an excellent window gets a R-5 rating. R-Value should not be your sole criterion.

The U-Value indicates the heat transfer rate. This is calculated by inverting the R-value 1/R. The lower it is the better insulation.

The ER Coefficient or Energy Rating (ER) calculation is based on the heat transfer U-Value, solar heat gain and air leakage. The higher the ER, the better the energy performance. ER value is the most accurate form of measurement for thermal performance of a window. A customer should always be looking for the Energy Star label that is placed on the most efficient products.

ENERGY STAR® Certification is a voluntary certification obtained by manufacturers. ENERGY STAR® certification is proof that a product is eco-energetic and that its insulation quality has been attested by an independent expert. There are products on the market today that offer excellent energy performance but are not ENERGY STAR® certified. It is up to the Consumer to inquire if their windows are ENERGY STAR®  certified.

If you would like more information on this certification, please visit:



Other label certifications should include permanent stickers such as the Gold Seal Label for ENERGY STAR®

Canada signifying the most efficient window, as well as a temporary label as required by the Building Code. 

Another great way to enjoy the maximum energy benefits from your windows is insulated frames. 

Contact Kehl for details on our All Season Premium window.