frequently asked questions
Please click on a question below to find out more about Bendheim Wall Systems.
For a glossary of terms, click here.
- Q1 - What is the difference between long wave and short wave infrared?
- Q2 - What are the Shading Coefficient and the Solar Heat Gain Coefficient?
- Q3 - What is better, a high or low shading coefficient?
- Q4 - What is safety glazing?
- Q5 - What are the U.S. Standards for testing safety glazing materials?
- Q6 - Where should safety glazing be used?
- Q7 - How is safety glazing marked for identification?
- Q8 - Is it better to have the coating on the #2 or #3 surface of an insulating glass unit?
- Q9 - Will Low-E glass work only in northern climates?
- Q10 - The industry offers Low-E coatings on the #2 surface and on the #3 surface of an insulating glass unit. On which surface should the coating be located to achieve optimal solar performance?
- Q11 - When is safety glazing required?
Q1 - What is the difference between long wave and short wave infrared?
- Short wave infrared energy comes directly from the sun but is not felt as heat. It converts into heat when it strikes something.
- Long wave infrared is the heat radiated from an object which has received short wave radiation, a hot automobile dashboard, for example, or a hot sidewalk or roadway where you can often see heat radiating from the surface.
Q2 - What are the Shading Coefficient and the Solar Heat Gain Coefficient?
A2 - These terms are mathematically related and both describe the solar energy blocked from passing through a glass material. The shading coefficient is the ratio of solar energy that passes through a piece of glass relative to piece of 1/8” clear glass ( which has a shading coefficient of 1.0. Solar heat gain coefficient represents the solar gain through the glass relative to the incident solar radiation; it is equal to 86% of the shading coefficient. In either case, a lower number indicates improved solar control over the 1/8” clear glass baseline.
Q3 - What is better, a high or low shading coefficient?
A3 - In colder, heating-dominated climates such as Canada or northern US, windows with higher shading coefficients generally are preferred and conserve energy. This so because in the longer heating season, more solar radiation, which becomes “free” heat is allowed to pass into a home.
In the south, with a long air-conditioning season, it is most important to reduce solar gain and therefore reduce air conditioning loads.
Q4 - What is safety glazing?
A4 - Glass is a breakable material, which when broken into smaller sharp pieces often called shards can cause serious injury. Safety glazing material, usually tempered glass or laminated glass, reduces the risk of injury. This is accomplished in the case of tempered by the characteristic break pattern-many small pieces, and by the adhesion of the glass pieces to the inner plastic layer in the case of laminated glass.
Q5 - What are the U.S. Standards for testing safety glazing materials?
A5 - ANSI Z97.1 and CPSC 16CFR, Part 1201.
Q6 - Where should safety glazing be used?
A6 - The Federal safety glazing law stipulates that safety glazing be used in architectural applications ( homes and buildings ) in defined hazardous locations. Generally the hazardous location include doors, immediately adjacent sidelites, bath and shower enclosures and glazing adjacent to passages where there are walking surfaces adjacent to the glass and the bottom edge of the glass is within 18” of the floor. In addition to the Federal law, various local code authorities have additional requirement.
Q7 - How is safety glazing marked for identification?
A7 - The Federal safety glazing law requires that all safety glazing products have a permanently identifiable marking on each piece. This marking cannot be removed without damaging or breaking the glass and is generally located in one of the corners of each piece.
Q8 - Is it better to have the coating on the #2 or #3 surface of an insulating glass unit?
A8 - The answer to this question is really dependent on the specific design conditions of your application. The light transmittance and U-Value of the unit will be the same whether the coating is on the #2 or #3 surface; however, the Solar Heat Gain Coefficient will be lower when the coating is on the #2 surface.
In general, if you are concerned about reducing solar heat gain (typically in a cooling climate), then using the coating on the #2 surface would best meet the requirement. On the other hand, if you are interested in utilizing passive solar heat gain (typically in a heating climate) then using the coating on the #3 surface would best meet the requirement.
Q9 - Will Low-E glass work only in northern climates?
A9 - No, low-e coated glass can work in all climates.
Low-e coatings reduce heat loss from the interior through windows, thus reducing the energy used to heat buildings and associated heating costs.
And, low-e coatings also offer solar control that reduces heat gain due to both the transmitted solar energy and conducted heat caused by indoor – outdoor temperature difference. This reduces cooling loads and consequently the energy and costs associates with cooling the building.
Q10 - The industry offers Low-E coatings on the #2 surface and on the #3 surface of an insulating glass unit. On which surface should the coating be located to achieve optimal solar performance?
A10 - According to the Glass Association of North America 2004 Glazing Manual, "A low-e coating on the second (#2) surface of an insulating glass unit is more effective at reducing solar heat gain, especially when used in conjunction with tinted glass. The low-e coating will reflect re-radiated heat (IR), while the tinted glass reduces the solar radiation through the glass, resulting in less glare and heat gain."
Product evaluations conducted by Viracon have revealed that surface 3 orientations of a low-e coating can act as a heat trap for commercial buildings, increasing the room-side glass temperature by as much as 13æF.
Q11 - When is safety glazing required?
A11 - First of all, what is safety glazing? Safety glazing meets the federal safety standard Consumer Product Safety Commission (CPSC) 16 CFR Part 1201 Safety Standard for Architectural Glazing Materials. Examples of safety glazing are fully tempered glass and a 7/32"laminated glass with a .030 PVB interlayer qualify as safety glazing materials.
Safety glazing is required in all doors including storm doors and combinations doors. This includes bathtub doors and enclosures, shower doors and enclosures and sliding glass doors. In addition, any glazing next to a door or an opening for human passage is considered a "sidelite" and requires safety glazing if the nearest exposed edge is:
- Within 24 horizontal inches of the vertical edge of the door in a closed position and
- Where the bottom exposed edge is less then 60 inches above the walking surface.
- The lowest edge of the glass is less than 18 vertical inches above a walking surface and
- The top edge of the glass is greater then 36" above the floor and
- There is a walking surface within 36 horizontal inches of such glazing; and
- The glazed panel is greater than 9 square feet.
The Consumer Products Safety Commission establishes the standards for safety glazing. Hazardous locations that require safety glazing are designated by the Model Building Codes. Because each state has either adopted the model building code, modified it in some sections, or written completely new sections it is imperative to be guided by the particular state or local building code where the glass is to be installed. For detailed information contact your local code officials.