What Replacement Window Energy Efficiency Rating Numbers Mean March 7, 2016 The moment you begin shopping for replacement windows for your Toronto area home, you’re going to come across a variety of different numbers. These numbers can refer to energy efficiency, or price. Of course, you probably already know everything you need to about price. What you might not know, though, are the R-values and U-Factors. These are values given to various replacement windows and doors to indicate just how energy-efficient they are. Here is a basic overview of what those numbers refer to. The U-Factor has a range between 0.20 to 1.20. The lower the number, the better the insulation is on those windows and doors. Recommendations for Canadians are any type of windows that are rated 0.35 or less with the U-Factor. This U-Factor is more about how much heat the glass allows through, especially during the summer. The R-value is the more common term and focuses on heat conduction. The higher the R-value for a window, the more energy efficient it is. Most replacement windows today have stickers affixed to them that indicate their U and R ratings. You want to find windows that have low U-factor ratings and high R-value ratings. The best place to start is to focus on a slow local, small to medium-sized window and door company. These companies will often provide the best quality windows and doors on the market. You may be able to find cheaper windows at your local home improvement megastore, and while they seem like a bargain and the sales people tell you they are plenty energy-efficient for the area, the fact is they are not. You have to avoid the temptation to bargain hunt when it comes to replacement windows. When you choose quality windows, you’re going to save money every month on your heating bills and you can also increase the value of your home. This may not seem important now, but if you end up putting your house on the market in the future, you can reap the benefits of those better quality replacement windows at that time. In the meantime, you’ll be warmer and it will cost you less to stay warm.