Glass can greatly affect energy use, light transmission, acoustics and facade strength. By understanding and applying each of these components, you can choose the right glass for your project.
Glass Performance
Glass contributes to a building’s energy performance by affecting both natural light transmission and solar control. Performance glass is measured by:
U Value of the Glass
Glass parameter characterizing the heat transfer through the middle part of the glass (ie without edge effects) and expressing the steady-state density of the heat transfer rate with respect to the temperature difference between the ambient temperatures on both sides. Temperature difference compared to standard conditions: delta T=15K°. The lower the value, the greater the insulation value.
Solar Factor of the Glass
It defines the total solar energy that passes through the glazing. A lower number = less solar energy transferred from the glass to the interior.
Light Transmittance of the Glass
It measures the percentage of visible light (in the wavelength range of 380 nm to 780 nm) passing through glass. Higher number = more natural light indoors.
Selectivity of the Glass
The selectivity is the light transmittance divided by the solar factor. A higher number = brighter areas linked to solar control performance.
Building Energy Efficiency
By affecting light transmission and solar heat, glass can improve occupant comfort and help the HVAC system operate at maximum efficiency.
High-selective high-performance glass allows buildings in hot climates to take advantage of natural light, eliminating the need to build up excessive temperatures indoors or to block light through a canopy. Meanwhile, buildings in colder climates can take advantage of the passive heating offered by high solar factor glazing.
Glass coatings with a lower U-Value have higher insulating properties and help keep the indoor temperature stable without being affected by outside weather conditions.
There is a wide variety of architectural glazing products that can provide harmony between aesthetics and energy efficiency.
Acoustic
There is constant sound all around us. Unfortunately, sounds that most of us enjoy, such as bird chirping or laughing, are drowned out by other less pleasant sounds. According to the World Health Organization, excessive noise seriously harms us. It can impair our sleep quality, cause cardiovascular and psychophysiological problems and lead to poor performance.
Sound is transmitted through glass because the molecules compress each other and radiate this compression as a wave. Noise can be reflected or absorbed by the glass to varying degrees, depending on the thickness of the glass and the combination of interlayers.
Resistance
Performance glass provides transparency and beauty as well as strength. This video shows several strength variations of different types of glass.
The original state of all architectural glass has not been heat treated. However, greater load resistance can be achieved by applying heat treatment. In this process, the glass is carefully heated and then its surfaces are rapidly cooled to achieve permanent compression. It is important to note that the glass must be cut and mounted before processing. There are two types of heat treated glass:
- Tempered glass is about 4 times stronger than non-heat-treated (standard) glass. It is designed to break into relatively less sharp small pieces when broken. Tempered glass can be described as safety glass in this respect.
- Heat-strengthened glass is approximately 2 times stronger than non-heat-treated glass. When broken, pieces of glass are more likely to be retained within the glass panel frame than tempered glass.