Whether you are building a greenhouse or upgrading your home's windows, selecting the correct glass is critical and should be viewed as a 20 year or longer investment. You should consider several factors when planning for glass, including the type of application, location of the structure, and privacy. These concerns can be addressed with the appropriate glass unit, type, and tint/coating selection.
First, you must choose between single pane or insulated (double or triple pane) glass. Insulated glass is recommended for locations that require heating and/or cooling. The layer(s) of glass with an air space(s) helps limit heat transfer into or out of a building. Single pane, or monolithic glass, is typically recommended for interior applications or those geographic locations which experience little to no temperature fluctuation throughout the seasons. Monolithic glass has little insulation ability, so when cold air or water touches the glass, the cold is quickly transferred into space.
The next step is to choose from annealed, tempered, or laminated glass. These three terms describe the processes used to produce the glass, and each variety is stronger and more impact resistant than the other. Annealed glass is generally used in interior or decorative applications, but it is not suitable for glass structures because if broken, it shatters into sharp jagged pieces. Tempered glass is recommended for use indoors, in windows, and on glass walls because it is firm and resistant to impacts. If breakage should occur, tempered glass shatters into small squares. Laminated glass is recommended and often required for use in the roofs of glass structures and skylights. This type of glass has a plastic layer manufactured into the glass to contain glass pieces if breakage occurs. Laminated glass shatters into pieces that look like a spider web but do not fall out of the frame due to the plastic layer. It also blocks 99% of harmful UV rays. Before selecting your glass type, be sure to refer to IRC local building codes and the product manufacturer for additional requirements.
The last step is to choose an appropriate coating for the glass. Color tints can be used to adjust the glass’s aesthetic and performance. Low-emissivity or LowE glass enhances glass performance, including insulation value, light transmittance, and solar heat gain. LowE reduces heat transfer and prevents the fabric from fading by reducing the UV-rays that enter the space.
When choosing a glass coating, there are five factors you should take into consideration: Visible light transmittance (VT), Solar heat gain coefficient (SHGC), U-value, R-Value, and UV transmittance. VT refers to the amount of visible light that passes through the glass; the higher the VT, the more natural light will enter the space. SHGC describes the amount of solar heat that passes into a room; the lower the number, the better the performance. The U-Value describes the glass's ability to conduct heat, while the R-Value is the inverse and describes the glass’s resistance to heat gain or loss. For example, glass with a low U-Value and high R-value will maintain cooled or heated air inside a room. UV transmittance describes the amount of UV energy that will pass through the glass; the lower the number, the better the coating is at preventing the fabric from fading.
Once you have determined the unit size, type, and tint of glass that will suit your needs, it is time to find a dealer. Solar Innovations, Inc. has over 16 years of experience manufacturing custom glass structures and is available to answer any questions you may have.
