Condensation Resistance Window Ratings – AAMA Versus CRF

Condensation is moisture that forms on surfaces, particularly windows, when the surface is cooler than the dew point, or the temperature in which water vapor in the air converts into liquid. The amount of condensation that collects on windows can vary significantly depending on the type of window. For instance, single pane windows are more likely to be prone to condensation than double pane windows – this is because single pane windows have less insulating properties, and condensation is more likely to accumulate on cold surfaces.

To gauge a window’s expected performance at resisting the buildup of condensation, window ratings were developed for comparison sake for buyers to be able to determine if a window can meet the condensation resistance needs of the building environment. For example, buildings in cold climates or buildings prone to high interior humidity levels due to moisture-building industry processes, may require windows with a higher condensation resistance rating.

There are two different ratings that window buyers can use to make their decisions: the Condensation Resistance Factor (CRF), developed by the American Architectural Manufacturers Association (AAMA) and the Condensation Resistance (CR) rating by the National Fenestration Council (NFC).

The AAMA’s CRF rating vs. NFC’s CR rating – what’s the difference?

Two rival ratings for measuring the ability for windows to resist condensation resistance can be confusing.
• The AAMA’s CRF rating is a system that ranges from 30 to 80, with higher numbers being indicative of better condensation resistance.
• The NFC’s CR rating ranges from 0 to 100, and the higher the number, the better at resisting condensation on windows.
• The main difference between these two ratings is how they are calculated: the AAMA’s CRF rating is determined using measured data calculations, while the NFC’s CR rating is determined with simulation.

While window experts may debate on the merits of one rating over the other, there is one factor that is generally agreed upon: the need to address condensation accumulation issues. Excess moisture can cause severe decay and damage to walls and even building structure. Regardless of the specific window, it is imperative to look for a model that insulates, as well as prevents air leakage.

A perfect solution is an interior window system, which installs on the inside of existing windows in order to immediately improve thermal performance and air infiltration. Contact Thermolite today to learn how our interior window systems are a cost effective way to reduce condensation in your building.

Stay up-to-date on Thermolite’s latest blog posts:

The Thermolite engineering staff is an innovative structural, energy modelling, and implementation team that works to create unique window systems alternatives to traditional replacement windows. Our systems protect against blasts, hurricanes, and sound, while being energy efficient and quick and easy to install. We serve a wide range of industry buildings including government, military, historical, schools and universities, financial, health care, hospitality, and offices. Contact us today to learn how we could update your building’s window systems.

References:
http://www.greenbuildingadvisor.com/blogs/dept/musings/rating-windows-condensation-resistance