Understanding Energy Ratings on Replacement Windows and Doors

The National Fenestration Rating Council (NRFC) is a voluntary program that tests and certifies windows and doors based on energy performance. They then label these products according to their ratings. These labels on replacement windows and doors in Sherwood, OR can help you compare products. That way you are sure to find the best products for your home and budget. But what if you don’t understand what you are looking at? We are here to help. Here is some information about the ratings you will find on these energy labels.   

Ratings for Heat Gains and Losses 

The replacement windows and doors can lose heat through glass, frames, and doors. It can also be lost through radiation and air leaks. Manufactures use three main ratings to measure in this regard:  

1. U-Factor

This measurement represents how a product conducts non-solar heat. This is usually expressed in units between 0.20 and 1.20. Lower ratings mean the product prevents heat transfer. This is important in Oregon where you use your heating more often throughout the year.   

2. Solar Heat Gain Coefficient (SHGC)

This rating references how well windows and doors prevent heat gains from the sun from entering the home. Ratings go from 0 to 1. Lower values mean the products insulate better. In winter it is nice to have heat from the sun transfer inside. But in summer, not so much. Try finding products around 0.5 or less for optimal performance in the local climate.   

3. Air Leakage

No product can provide a perfect seal. There will always be some level of air leakage, especially in areas with high wind. Luckily there is a rating to show how much air filters through windows and doors into the home. These ratings range from 0.1 to 0.3 cubic feet per minute per square foot. Lower ratings means these products are even more airtight. Also, the air leakage rating largely depends on proper installation and maintenance.    

Ratings for Sunlight Transmittance 

Other references on an energy label communicate how well a product transmits natural light into the home. Two main ratings are:  

1. Visible Transmittance

This measurement represents a fraction of the visible light spectrum of sunlight transmitted through the glazing on a window or door. References go from 0 to 1, and higher VT means you can enjoy more visible light. This is important when you consider east or west facing bedrooms or television rooms. How much do you want to limit interior glare in these spaces?   

2. Light to Solar Gain (LSG)

Another reference you might find on energy labels is the LSG. This is the ratio between SHGC and VT. It allows you to gauge the efficiency of different glazing options. Do you want windows that transmit daylight and block heat? Or do you want to cut down on unwanted sunlight and transmit heat? The higher the LSG the more light filters through while blocking unwanted heat gains.   

Want help decoding the ratings on Sherwood, OR replacement windows and doors? Call EnergyGuard Windows & Doors today. Our experts can pin down which ratings are best for certain areas of your home. That way you can get efficient windows in every space. Contact us at (503) 554-5500 or visit our location at 516 E. 2nd St., Newberg, OR 97132.