Double Insulating Glazed Units
Discover the soft-coating double insulating glazed units that are widely appreciated by customers across Western Europe
- Introduction
- Glass Through the Ages
- AGC Glass Europe
- Coated Solar Control Insulating Glazed Units
- Technical characteristics (of coated or non-coated) glazed units
- Sealing of Double Insulating Glazed Units
- Glass Maintenance and Cleaning Instructions
- CERTIFICATION
Introduction
Today, thermal insulation in buildings is a key concern regardless of their use, whether private residence, rental, commercial, or tourist accommodation and whether they are newly built or undergoing renovation
Improved insulation means:
During winter, doors and windows account for 35% of a home’s heat loss, while in the summer months, solar energy enters the interior, becoming trapped and causing the well-known “greenhouse effect”, creating an unpleasant environment.
The glass industry is actively addressing these challenges by investing in research, resulting in more efficient glass panes for consumers.
The importance and effectiveness of coated glass panes in building thermal insulation is undisputed by all relevant official authorities today. On the contrary, European governments, aiming to reduce energy consumption and curtail national emissions, offer subsidies for the replacement of standard double glazing with coated insulated glazed units in buildings. A similar program is also running in Greece (‘Exoikonomo Kat’ Oikon’), which includes, among other things, the replacement of window frames and glazed units.
Since early 2012, Bouzakis S.A. has included in its product range high-performance soft-coated glazed units, equivalent to those enjoyed by consumers in Western Europe.
These advanced glazed units require equally advanced handling during their transformation into double-glazed units. To meet this demand, in early 2015 the company implemented an investment plan to modernize its production equipment. This investment focuses on the automation of double insulating glazed unit (IGU) production and enables the company to:
Glass Through the Ages
Glass exists in nature as a mineral, but the first man-made glass objects have been discovered in Egypt and date back to 5,000 BC. Flat glass, intended for its primary and enduring use, i.e., filling window openings, first appeared in Ancient Rome in the 1st century BC. Glass was installed in Roman homes to provide protection from the weather while allowing natural light to enter the house, much like today.
Over the centuries, glassmaking continued to evolve slowly until the Industrial Revolution and the 20th century, when the most significant changes took place.
During this period, scientists observed that glass, apart from its beneficial properties (hard, chemically resistant, transparent and color-neutral, environmentally friendly, etc.), was the “weak link” in the thermal insulation of buildings.
The discovery of double glazing in 1934, i.e. the use of two parallel glass panes with a gap between them as a single insulating unit, stood for years as the most significant innovation in the use of glass in the construction industry, as it provided the primary technical requirement of insulating glass: thermal protection.
Further research for improved thermal insulation and climate comfort led the glass industry to develop coatings (low-e and solar control) for glazed units. These glazed units were developed to control solar radiation and heat, providing people with a better and more cost-effective indoor environment.
The earliest produced coated glazed units were hard-coated, manufactured through a direct coating process where metal oxides are applied at high temperatures onto glass and then fused to the surface by pyrolysis. This process creates a highly durable and long-lasting coating. As a result, no special handling is required in terms of storage, cutting, thermal toughening, conversion into laminated glass, or any other processing.
Over the past decade, the glass industry has introduced high-performance coated glazed units (soft-coated), produced by “spraying” metallic particles onto the glass using electromagnetic vacuum deposition. This process results in glazed units with superior technical characteristics compared to their hard-coated counterparts.
AGC Glass Europe
The company imports, processes, and distributes insulating glazed units from AGC Glass Europe (formerly Glaverbel), headquartered in Belgium and Brussels.
AGC Glass Europe manufactures, processes, and distributes flat glass for the construction industry (including glazing for exterior frames and interior design), the automotive industry, the solar energy sector, and a range of advanced industrial applications. It stands out for its Research and Development center, as well as its 18 glass production facilities spread across Europe, from Spain to Russia. The company employs approximately 10,700 people across its operations.
AGC Glass Europe is one of the four leading manufacturers of architectural and industrial glass units in Europe. It is a member of “Glass for Europe”, the European association of glass manufacturers, and operates as the European branch and subsidiary of the Asian industrial giant, Asahi Group.
AGC Glass Europe produces and distributes its specialized insulating glass units in Greece (including Sunergy, EnergyN, Stopray Ultra50, as well as the painted Lacobel series) through its main manufacturing plants in Belgium. Standard glass units, including laminated (triplex) types, are produced and distributed to the Greek market from both Belgium and Italy. As for the Iplus Light series, these glass units are manufactured exclusively in Italy.
Coated Solar Control Insulating Glazed Units
Due to Crete’s unique geographical and climatic conditions, characterized by a Mediterranean climate with low winter temperatures and high summer temperatures, the company recommends coated glazed units that combine solar control and thermal insulation within a single coating. At the same time, other factors such as the glazed units’ visible light transmission and their reflectance (particularly internal reflectance) are carefully considered.
The special coated glazed units selected by the company for import from AGC Glass Europe, deemed suitable for Crete’s bioclimate and recommended to customers, are the following:
Sunergy is a popular second-generation hard-coated solar control insulating glazed unit. It is a reliable specialty glass that, for over a decade, has created synergies by combining solar control, thermal insulation, and visual neutrality in both brightness and reflectance.
The ipluslight is an economical option among soft-coated glazed units.
In terms of thermal insulation, it outperforms the Sunergy unit, following the performance standards typical of all soft-coated glazed units. Regarding solar performance, it is also superior to Sunergy. However, it exhibits increased reflectance (25% external reflectance, 23% internal reflectance) as it is essentially a semi-reflective glazed unit.
The company’s second offering regarding magnetic (soft) coated glass is EnergyN, a third-generation solar control insulating glazed unit. It is an outstanding glazed unit that presents a range of very valuable features.
EnergyN has the ability to reflect a large portion of solar energy during the summer, while providing strong thermal insulation against the cold in winter, thus offering thermal comfort throughout the year and saving energy on both cooling and heating. This improves the quality of life inside the home.
At the same time, it demonstrates high visual neutrality, as its appearance is similar to that of a standard double-glazed unit. It allows large amounts of natural light to enter the home and has very low reflectivity, both internally and externally, providing visual comfort and reducing energy consumption for artificial lighting.
The Stopray Ultra50 belongs to a completely new generation of glazing products, that of high-performance solar control insulating glazed units. It represents the company’s top offering and one of the best in the market in terms of performance, making it a wise investment for anyone choosing it, as it significantly reduces overall energy costs.
It is produced, like EnergyN, by AGC Glass Europe using the same manufacturing technology (magnetic soft coating under vacuum), on extra-clear rather than standard glass. However, it offers a differentiated mix of technical characteristics compared to the aforementioned product, in order to meet different needs.
Technical characteristics (of coated or non-coated) glazed units
GLAZED UNIT TYPE | Light Transmission Coefficients | Solar Factor | Selectivity | |||
Brightness | Reflection | Internal reflection | SF (%) | Selectivity ( 0 > S > 2 ) | ||
Single glazed unit | 5mm | 89 | 8 | 8 | 85 | 1.05 |
Double glazed unit | 5 – 16 – 4 | 81 | 14 | 15 | 76 | 1.07 |
Double glazed units | 5 – 16 – planibelG 4 | 74 | 17 | 16 | 70 | 1.06 |
Sunergy clear 6 – 16 – 4 | 61 | 12 | 16 | 51 | 1.20 | |
Double glazed units | EnergyN 6 – 16 – 4 | 72 | 12 | 13 | 40 | 1.80 |
Stopray Ultra50 | 49 | 18 | 14 | 23 | 2.13 | |
GLAZED UNIT TYPE | Light Transmission Coefficients | ||
U-Value (w/m2K) | |||
air | argon 90% | ||
Single glazed unit | 5mm | 5.8 | – |
Double glazed unit | 5 – 16 – 4 | 2.7 | 2.6 |
Double glazed unit | 5 – 16 – planibelG 4 | 1.7 | 1.5 |
Sunergy clear 6 – 16 – 4 | 2.0 | 1.8 | |
Double glazed units | EnergyN 6 – 16 – 4 | 1.3 | 1.0 |
Stopray Ultra50 6 – 16 – 4 | 1.3 | 1.0 | |
Sealing of Double Insulating Glazed Units
In order for a double insulating unit to comply with international standards, specifically the guidelines described in European Union Standard EN 1279-5, it must have double sealing, i.e. sealing on two levels between the two panes of glass that make up the double glazing.
The primary sealing involves sealing the spacer to the two glass panes. Spacers are usually made of aluminum, and more rarely from warm-edge materials. Before the primary sealing, the spacers are filled with silica gel, which is essential for dehumidifying the sealed cavity.
There are two ways to perform this first sealing:
Sealing with tape
A cold-applied double-sided tape is adhered to both sides of the spacer in order to secure it between the inner and outer glass panes. This tape is made of a special material that ensures airtightness and long-term durability. It must be concealed within the rebate of the frame and not exposed to sunlight, as this would cause it to lose its properties.
Butyl
Butyl is a superior material compared to the tape and requires specialized equipment for application. It is essentially a solid adhesive that becomes fluid when heated. It first bonds to both sides of the spacer, and then, by applying pressure with a special press on the two glass panes, the seal is securely formed.
Secondary sealing is achieved with adhesives, which are divided into three main categories:
Hot-Melt Adhesive
The hot-melt adhesive is applied using a heat gun that warms it, and as it cools down, the adhesive solidifies. It is the most widely used adhesive in our country as it is easy and quick to apply and, above all, has a short setting time. The downside is that it is not as durable as the other two types described below at very low and very high temperatures. Additionally, delamination may occur when bonding glazed units with coatings that increase surface temperature.
Thiokol
Thiokol is a two-component sealant applied using a specialized machine that automatically mixes the two components during application. It offers superior mechanical performance compared to hot-melt sealants, as it is not affected by weather conditions. Its main drawback compared to hot-melt is its longer curing time, which typically takes around 24 hours.
Silicone-Based Sealants
These are used more rarely due to their higher cost, mainly in constructions where the sealant is exposed to solar radiation, such as structural glazing systems.
Hot-melt and thiokol sealants should not be exposed to weather conditions, unlike silicone-based sealants. However, all three types of sealants must fully cover the gap between the two glass panes and come into contact with the primary sealant material. Typically, the first and second sealing layers involve a combination of one hot-applied and one cold-applied material, such as hot-melt tape, and butyl with thiokol.
However, when the sealing materials are directly exposed to sunlight (as in structural glazing systems), the use of silicone-based sealants is considered essential.
Glass Maintenance and Cleaning Instructions
When glass is cleaned for the first time (after installation), it can be particularly dirty. We recommend informing the cleaning personnel to follow the steps below:
Notice:
The above information is provided for guidance only. The company accepts no liability in cases of improper use of this information or if the glass surfaces develop scratches during the cleaning process.
CERTIFICATION
The application of the CE mark on products intended for use in buildings is mandatory within the EU. The double glazed units manufactured by the company comply with the requirements of the directives described in European Union standard EN 1279-5. Accordingly, the company has been granted the necessary certifications and the license to use the CE marking.