+359 892 07 55 55

n_milanov@tdm-plast.com
271 Tekstilets St.

Vratsa, Bulgaria
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Sunday: Non-working day

 

Glass & Glazing

It is well known that a window consists primarily of a profile and a double or triple-glazed unit.

 

Which is more important? Considering that the glass surface area is many times larger, the glazing unit is more critical. Of course, multi-chamber joinery combined with an effective glazing unit is the best solution, but if a choice must be made – you should prioritize the glazing.

 

A glazing unit (or insulated glass unit) is a hermetically sealed structure consisting of two or more panes of glass, separated by a spacer (frame) and filled with dry air or an inert gas (argon). It is a fundamental element of modern joinery, providing effective thermal and sound insulation.

To possess good technical characteristics, a glazing unit must have two levels of sealing. A double-barrier glazing unit consists of a spacer frame filled with an adsorbent (molecular sieve). Butyl is applied to both sides of the frame, serving as a barrier against water vapor penetration (first level of sealing). The second barrier is the external sealing of the space between the glass panes and the spacer using a sealant—polysulfide. When a glazing unit is manufactured correctly, water cannot penetrate from the outside, and condensation cannot form between the glass panes.

The glazing unit accounts for about 80% of the entire window and has the greatest impact on its insulation characteristics. The most important indicators to consider when choosing a glazing unit are: Thermal Insulation U (W/m2 . K) – determines how much energy will be saved; Sound Insulation Rw (dB) – determines the level of noise that will enter the room through the glazing; Solar Factor g (%) – this is the sun protection or the factor indicating the amount of solar energy that will pass through the glass; Light Transmission (%) – indicating the amount of light entering the room.

Let’s examine and analyze the following table. It features the most commonly used types of glazing units in the production of PVC and aluminum windows and doors.

Double glazing unit (4mm + 4mm)
Visible Light Solar Energy Thermal Properties Acoustic Values
24mm. 32mm. 24mm. 32mm. 24mm. 32mm. 24mm. 32mm.
Clear + Clear 82,8 82,8 79,3 79,3 2,7 2,7 30 (-1;-4) 32 (-1;-4)
Clear + Low-E
(Ka)		 81,9 81,9 63,8 63,8 1,4 1,4 30 (-1;-4) 32 (-1;-4)
Clear + High-Energy (4-Seasons)
(4 сезона)		 66,9 66,9 42,5 42,5 1,3 1,3 30 (-1;-4) 32 (-1;-4)
Triple glazing unit (4mm + 4mm + 4mm)
Visible Light Solar Energy Thermal Properties Acoustic Values
32mm. 44mm. 32mm. 44mm. 32mm. 44mm. 32mm. 44mm.
Clear + Clear + Clear 76,0 76,0 72,0 72,1 2,0 1,8 31 (-1;-4) 32 (-1;-5)
Clear + Clear + Low-E (Ka) 75,0 75,0 58,8 58,7 1,4 1,1 31 (-1;-4) 32 (-1;-5)
Clear + Clear + 4 Seasons 61,9 61,9 39,8 39,7 1,4 1,0 31 (-1;-4) 32 (-1;-5)
Low-E (Ka) + Clear + 4 Seasons 60,9 60,9 38,6 38,5 1,1 0,7 31 (-1;-4) 32 (-1;-5)

In conclusion, we can say the following in accessible language:

The difference in parameters between 24mm and 32mm double glazing units is minimal, with the only noticeable difference being in sound insulation. In this case, the wider glazing unit simply comes with an unnecessarily high price.

With triple glazing units, besides what was mentioned above, the width of the air chamber is of immense importance. As you can see for yourselves, the most optimal width is achieved with a 44mm glazing unit (where the spacer is 15/16mm). The conclusion we can draw from both tables is that it is better to have a 24mm energy-saving double glazing unit than a 32mm triple one—unless you want to spend money unnecessarily. It is a different matter with the 44mm triple glazing; there, we have an optimal air chamber and, consequently, excellent performance. Therefore, we can say that an energy-saving glazing unit pays for itself over time, while a standard one brings no benefits—quite the opposite.

To summarize what is important:

  • Light transmission – the amount of light that enters through the glazing unit;
  • Solar factor – the amount of heat that enters from the outside in;
  • Thermal transmittance coefficient – the amount of heat that escapes from the inside out;
  • Sound insulation;
  • The width of the air chamber – in addition to seeking its optimal width, it is advisable for it to be filled with Argon gas rather than ordinary air. Its presence improves the thermal transmittance coefficient by 0.2 to 0.3 units. It should be in a ratio of 93% gas and 7% air. Due to its high volatility, it escapes through the micropores of the glazing unit sealant in about 5 years. This is why the standard European warranty provided is exactly that – 5 years.

But the choice of the glazing unit type is not the only thing that matters. The choice of the manufacturer is also a crucial factor. "TDM PLAST" Ltd. possesses a specially dedicated production base for manufacturing glazing units. The excellent facilities, modern high-tech equipment, specialized software, and well-trained staff guarantee the high quality of the produced glazing units.

In 2023, our workshop was equipped with the most modern automatic production line for glazing units by the "LISEC" brand. LISEC production lines are highly automated modular systems for flat glass processing, designed to combine cutting, edging, washing, and assembly of glazing units into a continuous production process.

Furthermore, since 2017, we have held all types of certificates and CE markings for the production of glazing units (regarding hermetic sealing and Argon gas filling) from the renowned Czech laboratory IKATES, s.r.o.

Here is the entire production process of glazing units at "TDM PLAST" Ltd.:

Automatic Loading and Glass Cutting: This is carried out using a robotic glass feeding system and a LIVA automatic cutting table. The table is equipped with a special milling cutter for Low-E coating removal.

LISEC KSR Processing Machine: Here, the cut flat glass is processed by grinding the periphery and shaping its edges.

LISEC Washing Machine: Equipped with 6 brushes and an automatic adjustment function based on the thickness and type of glass (including a sensor for Low-E coating).

Spacer Bar Application Station: Here, the spacer bar is applied manually.

having previously been machine-bent, filled with a molecular sieve, and coated with butyl. All of these actions are performed on machines that are part of the LISEC production line.

LISEC Panel Press with Gas Filler: A vacuum press for assembling double and triple glazing units, featuring the capability to fill them with Argon gas.

LISEC Glazing Sealing Robot: Automatic application of polysulfide for perfect corners.

And as the jewel in the crown of our production line:

LISEC Automatic Laminated Glass Cutting Table: Automatic glass cutting using a double-sided cutting head (top and bottom), with automatic foil removal and glass separation (breaking).

By trusting "TDM PLAST" Ltd. for the production of your glazing units, you are making an investment with a long-term and secure return!!!

Partners we have achieved a lot with!

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