Choosing the right glass for windows and doors is of essential importance, especially when it comes to improving energy efficiency and sound insulation in a room.
Structure of an Insulating Glass Unit (IGU) The glass unit represents over 80% of the window area and has the greatest impact on the insulating characteristics of the window—thermal insulation, sound insulation, sun protection, and light transmittance. For this reason, no compromises should be made in its selection. It is much more than just two or more sheets of glass joined together by a spacer bar and sealed with special components. Investing in a quality glass unit will pay off many times over in a relatively short period. To achieve good technical performance, an IGU must have two levels of sealing. A dual-seal glass unit consists of a spacer frame filled with desiccant, with butyl applied on both sides as a barrier against water vapor transmission (first level of sealing). The second barrier is the external sealing of the space between the glass panes and the spacer with polysulfide.
Advantages of a Thermoplastic Spacer (TPS) The latest technology involves manufacturing insulating glass units with a thermoplastic spacer, positioned as a product with the best linear thermal transmittance performance. It guarantees superior indoor comfort, excellent energy efficiency, and extremely low CO2 emissions. Key advantages of an IGU with a TPS spacer:
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High reliability resulting from the unique process of continuous spacer application (absence of connectors/corner joints).
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The spacer is applied to the glass at a high temperature, enabling immediate adhesion to the glass and ensuring optimal structural bonding of the unit. A very dense and seamless seal with the secondary sealant is achieved. This process eliminates defects such as human error during manual spacer placement (misalignment) and spots or dust on the frame.
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100% edge arrissing/grinding on all glass panes.
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Capability to manufacture insulating glass units up to 80 mm thick with 4 glass panes. 
Why is the Correct Choice of Glass Unit Important? The choice of an insulating glass unit is largely determined by energy efficiency standards. The minimum requirement is the installation of an IGU with low-emissivity (Low-E) glass. Other decisive factors include the geographical region, building purpose, and orientation towards the sun (East, West, North, South). Solar control—sun protection—is particularly crucial for our climate. Therefore, using Low-E glass alone is not sufficient; while it retains heat inside during winter, it can lead to overheating in summer. For enhanced comfort, Rolplast offers a specialized high-performance energy control glass (Planistar Sun Plus) in its range, combining thermal insulation and solar protection features. Depending on glass thickness, the solar factor of this glass is 42–43%, with a heat transfer coefficient (U-value) of 1.1 W/m²K. This pane is installed as the outer layer to prevent rooms from overheating during summer. For residential construction, triple-pane glass units using a combination of solar control, float (standard), and Low-E glass are recommended. In this configuration, the solar factor drops below 40%, and the U-value reaches 0.5 – 0.7 W/m²K depending on the overall thickness of the unit. For commercial properties, office centers, or public buildings, glazing depends on the architectural design and visual concept. Typically, glass types meeting specific aesthetic and functional requirements are selected. The trend favors neutral glass options with low external reflection and strong thermal insulation and solar control parameters. High-selectivity glass—representing the ratio of light transmittance to solar factor—is commonly integrated. 
Another safety requirement concerning roof glazing is that the inner pane must be laminated glass, while the outer pane must be toughened (tempered) or laminated glass. Additionally, for large glass facades and skylights, self-cleaning glass is recommended as it is easy to maintain and avoids condensation buildup on cold mornings.