For commercial property managers and building owners, the costs of a window replacement project might seem jaw-dropping, especially if you’ve replaced windows at home. The costs might just not seem to add up. Yet, judging the two types side-by-side is misleading; it’s an apples-to-oranges comparison.

Commercial and residential windows vary greatly in design. In fact, installing a residential window on a commercial property would be problematic. Major structural issues could arise, as well as problems with the window’s ability to withstand wind pressure. Plus, commercial windows are typically customized to fit specific building envelopes, glazed on-site, and require specialized equipment to properly hang them. This is a major driver of the added cost of commercial window installation. Finally, commercial building windows must limit the flow of solar energy to prevent the building from overheating.

In particular, there are three main differences between commercial and residential windows, including:


Specialized Glazing to Prevent Solar Heat Gain for Windows

Commercial properties are known as “internal-load dominated buildings.” This industry term refers to large well-populated buildings that generate a lot of internal heat, from people, lighting, computers and other equipment. These buildings are often cooled year-round to counteract the heat that is generated inside. Single-family homes, on the other hand, are “envelope-load dominated buildings.” They are not crowded, do not create a lot of internal heat, and rely on sunlight as a heating source.

What exactly does this have to do with windows? A lot. Commercial window glazing must be specially designed to limit solar heat gain. This can be accomplished using specialized coating and high-performance glazing, which ensures light is admitted through the window, without too much heat. When windows do not properly protect from solar heat gain, the building’s peak cooling loads can skyrocket, resulting in an increase in energy spending.  


NAFS Grade Ratings

The North American Fenestration Standard (NAFS) is a rating system for windows that’s based on a variety of factors, including their ability to carry a structural load and withstand wind pressure, among other factors. These ratings are important for mid-rise, high-rise, and other commercial buildings, as their windows are exposed to higher wind pressures, the elements and often much higher structural loads.

There are four ratings including R (residential), LC (light commercial), CW and AW. Commercial windows often must carry a heavier load due in part to their larger size. Therefore, they’re designed with thicker, heavier duty frames and reinforced glazing. Residential windows, on the other hand, have smaller structural load capacities, and since they’re smaller, they aren’t subjected to high-pressure winds. Installing the improper windows on a commercial property could potentially lead to a number of structural issues.


Cost of Customization and Installation

Commercial grade frames – in the LC, CW and AW categories – are thicker and require more material to build. The end result: They’re more expensive than lighter-duty residential frames. Plus, many commercial building projects require frames that are completely custom-built, which can also add to costs. Yet, the installation process for residential and commercial windows is another major difference. Commercial window installations, in some cases, are much more time intensive and complicated. Specialized equipment is often necessary to properly hang and place large windows, and on mid-rise and high-rise buildings, cranes are required to reach high-story windows from the exterior. This increases the costs and time required for an installation project.


To most, it may seem that residential and commercial windows are one and the same. Yet, that doesn’t take into consideration some very important differences in their design, installation requirements, and efficiency ratings.

If you are looking for commercial windows, please contact us today