The portion of solar radiation remaining in the glass and heating the pane. Normal, light glass absorbs less radiation than coloured glass. Additional coatings can absorb more or less depending on the structure.
arcon® Lexicon
The lexicon from A to Z
A
Alarm glass refers to glass products with an alarm loop. The following versions are possible: as an electrically conductive paste baked onto thermally toughened safety glass, as a meandering wire inserted in the composite foil of the laminated safety glass or as a conductive functional layer on thermally toughened safety glass. The electrical resistance changes when the glass, the wire or the conductor loop breaks. A system attached recognises this difference and triggers an alarm.
Anisotropies indicate a disturbing effect with thermally toughened safety glass. The pre-stressing process introduces different stresses into the glass which cause birefringence in the glass. These birefringences, also called anisotropies, are perceived in polarised light as disturbing optical effects. Polarised light is present in normal daylight.
Usually, such anisotropies are perceived as grey rings, stripes or leopard patterns. As the glass thickness increases, the effect becomes more pronounced. This can also be accentuated when occurring in tempered glass with modern solar protection coatings because coloured effects result from the grey patterns.
ANISOTROPY OF GLASS FACADES IS AVOIDABLE.
The topic of anisotropy has gained importance in specifications of glass for the architectural field. Although they are not a flaw according to current standards, architects, facade designers and builders are affected by this visible effect as it seriously impairs the visual appearance of a glass facade. This edition of ISOLAR® Compass raises the issue of the visual assessment of anisotropies and describes an objective measurement procedure that allows a robust and fair assessment of glass for anisotropies.
Characteristics of old glass, such as bubbles, streaks, planing, rough spots, indentations or scratches, are particularly emphasised in antique glass. A distinction is made between two production techniques: manually blown or machine produced antique glass.
Approval in an individual case, issued by the highest building supervisory authority of the respective Federal state, issued at the request of the client, is a case-related individual approval, and limited to the respective construction project.
B
Ball impact proof glazing is regulated according to DIN 18032-3. Ball impact safety is considered to be achieved if components remain functional under mechanical stress from balls without significant change of the elements and their substructure. The abovementioned standard describes a method by which the ball impact safety of sports hall components (for example windows, doors, glazing) is tested. This test procedure applies to all components that can be hit in the building interior by the following ball types: Football, hand ball, hockey, medicine, tennis, bowling and volleyball.
When bending glazing, one side is compressed, the other stretched. The high strength is based on a compressive stress on the surfaces and a tensile stress in the core.
Borosilicate glass is rich in silicon and boric acid, which has high chemical resistance, low thermal expansion and high thermal shock resistance. Borosilicate glass is usually used as Class G fire resistant glazing. The glass is manufactured either in the drawing or float process.
Primary seal for insulating glass based on polyisobutylene (permanent plastic sealant).
C
It is essential to protect glass surfaces before contact with alkaline building materials such as cement, lime and the like, as they quickly cause irreparable damage to glass products. Intensive lyes to remove old paint on wooden frames, etc. must be removed from the pane surfaces when wet.
Glazing sealants and glazing blocks must be chemically compatible with the sealants of the insulating glass edge seal and the semi-finished products used in the insulating glass. In particular, this means that migrations of plasticizers between the glazing sealants with detrimental consequences for the functions of the ISOLAR glass, such as optical impairments are to be excluded. With regard to the selection of glazing sealants, the respective ISOLAR companies, in cooperation with their respective suppliers, can be of assistance for the sealants for the ISOLAR glass edge seal. Glazing blocks made of recycled material containing styrene or polystyrene are unsuitable for the glazing of ISOLAR glasses.
The use of anti-reflective glass improves the transparency and avoidance of disturbing reflections and mirroring. By careful matt etching, adapted refractive indices, by applying special coating systems or by forming thin surface layers, the reflection can be reduced.
High-tech on the glass surface
The quality of the optical surface is particularly important on the transparent material glass. At the same time, the surface offers unique possibilities to add extra functionality to glass products, A number of product properties such as transparency, reflection or emission capacity for electro-magnetic radiation can be critically affected by the surface.
Energy saving with coating technology
The energy saving properties of heat insulating glass are mainly the result of state-of-the-art coating technology. The same applies to the properties of solar protection glass. Both types of functional glass owe their effectiveness to the coatings, which are applied to the glass surface in a process known as the “magnetron technique”.
Low reflection glass
Low reflection glass is called for where any reflection must not, or should not, hamper the view. This is relevant in a number of safety applications, and also, for example, in display window units for exclusive products, or the display of exhibits behind glass. Special coating techniques can help eliminate the reflection of light on the glass surfaces almost completely. Low-reflection glass enables the combination of low-reflection glass surfaces with heat insulating properties.
“Low maintenance” glass
How does glass react to contaminants and dirt of any kind? The glass surface is also critical here. New materials and technology on the surface of the glass help make it easier to maintain glass surfaces and increase the length of time until it needs to be cleaned again. Glass surfaces can be coated in such a way that any liquids just “drip off”. On the other hand, there are also coatings where water forms an even film. It is also possible to create coatings which can destroy organic dirt.
The colour impression of insulating glass can also be described with the help of physical characteristics. The reflection colours are characterised by viewing from the outside and when viewing from the inside, as well as the colours when looking through from the outside to the inside and from the inside to the outside. In the case of all four colour impressions to be mentioned, the physical perception as well as the subjective perception of the human eye are of importance.
The latter is also heavily dependent on the influences dominated by the respective light and/or lighting conditions. All the aforementioned colour impressions are subject to the fluctuations which are possible in ongoing production. Absolute colour uniformity is therefore not always possible, especially with coated glasses. In particular, colour deviations can not be ruled out when using coated glasses of different origin in the same building as well as for subsequent deliveries and retrofitting of insulating glass with coated surfaces.
The colour rendering characteristics of the daylight transmitted are described by the general colour rendering index Ra. The reference illuminant is D65 or the radiation of the most similar colour temperature.
Especially in autumn and spring, a surprising phenomenon is occasionally observed in the morning. On the outside (weather side) of insulating glass condensate has formed, which later slowly disappears by itself again. How is this possible, when glass surfaces in windows and facades are mainly there to provide an unobstructed view to the outside?
On closer inspection, there is a completely natural explanation for this seemingly new phenomenon. The exterior of the thermal insulating glass, like many other surfaces, is in “radiation exchange”
with the sky. The outer pane releases heat thereby and becomes colder on the outside. How much heat the outer pane emits depends above all on the “radiation temperature” of the sky. A clear, “cold” night sky has an extremely low “radiation temperature”. This can be for example -40 to -50°C.
How much the outside of the insulating glass cools down also depends on how fast it is supplied with “replenishment” of heat. Thermal insulating glass prevents this supply - and the better the thermal insulation or the smaller the U-value.
Condensate on the outside can form if two conditions are met:
The outside must be colder than the surrounding outside air and the outside air must be saturated with moisture. Then the air on the colder pane cools down even further and the pane fogs up. This fogging up has a name: Dew.
When the outside air gets warmer in the morning, the dew “evaporates” again and the fog disappears. Condensate on the outside of insulating glass is therefore a natural thing and a sign of particularly good thermal insulation.
The room air is able to absorb significant amounts of moisture depending on the temperature. As soon as the temperature drops below the dew point on cold surfaces, some of the moisture from the room air can precipitate there as condensate. If the outside air is colder than the room air, the room-side surface of insulating glass is always colder than the room air. The lower the U-value or k-value of an insulating glass, the warmer is its room-side surface under the same conditions, and the rarer condensate would be there. An important factor for the formation of condensate on cold surfaces is also the degree of saturation of the room air with moisture (bathrooms, kitchens, bedrooms). The most important measure for the regulation of the air humidity is the targeted ventilation of the respective rooms. The heat transfer is increased in all insulating glass in the edge region. This can be seen by the formation of condensate on the room side in the edge area.
Special glass for new paths in architecture
The desire for large scale application makes glass a material of the 21st century. The step from a physical barrier to a constructive element has been taken. Above all, constructions using point-fixed glass elements are a visible sign of this trend.
In this area, glass must overcome completely new challenges. Unlike all traditional applications, the glass elements must also bear the forces they are subject to. Therefore the choice of glass and sizing must consider regulations and safety aspects which are radically different to those of the past. It is also absolutely imperative that gaining subsequent approval from the building regulation authorities is considered at the planning stage.
With regard to point-fixed constructions, we differentiate fundamentally between types of fixings (round head or countersunk head), the different bolt types (fixed or articulated) and the different options for connection to the structure itself.
New special glass products and as yet unknown challenges for glass refinement and processing are an inevitable consequence of the new applications for the raw material glass.
ISOLAR® has years of experience in manufacturing the special glass required and in implementation of projects with a wide range of different point-fixed glass constructions. In 2003, the German Institute for Structural Engineering granted a general building inspectorate approval for a system of point-fixed glass facades designed completely within the group.
D
In the case of composite and laminated safety glass, it may be necessary to detach the glasses from the intermediate layer even years after production or installation. This is called delamination. Among others, the hygroscopic (hydrophilic) property of PVB (polyvinyl butyral) under high thermal stress and high humidity are called into question. Likewise, material incompatibilities in the contact of PVB with certain silicones may be the trigger.
The insulating glass system prevents pressure equalisation of the gas or air volume trapped between the panes with the ambient air. When the climatic conditions change in comparison to the conditions in the production of the insulating glass, the general gas laws apply to the gas or the air in the cavity. The behaviour of the insulating glass system is influenced by ambient temperatures, sun irradiation, weather conditions (air pressure) and installation altitude compared with the altitude during production.
The result may be pressure changes in the cavity and deformations of the glass surfaces. The use of panes with increased absorption of sun irradiation (e.g., coated or mass-coloured glass) and large cavities can enhance this effect. In the case of insulating glass with asymmetrical glass structure (for example sound insulating glass, security glazing) this can lead to extreme loads on the insulating glass unit in the case of unfavourable pane formats. These influences are system dependent and can not be avoided.
E
The edge seal is a component of the insulating glazing and refers to the elements that join the panes with a special spacer (aluminium, stainless steel or plastic) and adhesives and sealants. On the one hand, the edge seal has the task of preventing the penetration of water vapour into the cavity and, on the other hand, of preventing the escape of the air or gas mixture from the cavity.
Emissivity is the ratio of the amount of energy radiated by a body to the amount of energy emitted by a black body under the same temperature conditions.
Thermal radiation is essential for the heat loss of glass, according to the emissivity of the glass surface. The emission is around Ɛ = 0.85 for uncoated glass. Simply stated: 85% of the heat absorbed by the glass is released on the glass surface.
Enamelled glass is referred to as flat glass, which is usually coated with one or more layers of coloured glass melt paint which is then baked or melted. In the baking process, the glass is generally simultaneously preloaded or partially pre-stressed.
In rare cases,the formation of a milky grey, misty film has occurred on the outer glass surface of the outer pane of insulating glass, which occurred again a period of time after cleaning the glass surface. This surface disappears only after a very long period of time. In-depth laboratory tests have so far only shown that this is an organic coating.
Since the organic substances found in the coverings are neither used in the production nor in the further processing of float glass by the manufacturer of insulating glass, nor do the glass surfaces come into contact with organic vapours or with these substances, it is almost certainly the case that the prevailing conditions for contamination of the glass surfaces and thus responsible for a change in the wetting reaction are at the place of installation.
Evaporation from, for example, paints, floor coverings or other materials in the vicinity of the glass elements can cause this phenomenon. This appearance is not a defect.
F
The fall heights are defined in the respective State building regulations. It is defined there from which height difference certain areas should be secured/protected against the fall of persons.
According to the model building code, fall safeguarding in, on and above structures is required if there is a danger of falling ≥ 1 m. In this case, the surfaces must be provided with fall safeguarding. Other regulations may apply in the respective State building regulations.
Fire resistant glazed elements are tested systems of frames and infills (glass), sealants and auxiliary materials which, in the event of a flashover over the test period, oppose the following resistances in accordance with DIN EN 357 “Fire-resistant glazing made of transparent or translucent glass products”:
- Load bearing capacity R
- Room closure E
- Radiation reduction W
- Isolation I
- Smoke protection S
- Self-closing C
The classification of a system always consists of a combination of one or more letters and the associated minutes of the resistance time.
The letter G (designation from DIN 4102) corresponds to the letter E (designation for room closure from DIN EN 357), the letter F has the equivalent EI (room closure and insulation).
Further requirements are formulated in DIN 4102 “Fire resistance of building materials and components” and DIN EN 13501-1 “Classification of construction products and types of fire behaviour”.
Proper processing of the system may only be carried out by the applicant for the technical approval of the fire protection system - certified companies in accordance with the requirements of technical approval (abZ) or ZiE.
Fire retardant
Building designation of the State building regulation corresponds to a fire resistance of 30 minutes, e.g. F (EI) 30 or G (E) 30.
Highly fire retardant
Building designation of the State building regulations corresponds to a fire resistance of 60 minutes, e.g. F (EI) 60 or G (E) 60.
Fire resistant
Building designation of the State building regulations corresponds to a fire resistance of 90 minutes, e.g. F (EI) 90 or G (E) 90.
Fire resistance classes according to DIN 4102 for fire resistant glazing
Fire resistance class G (E): Translucent building elements that prevent the propagation of fire and smoke according to their fire resistance duration, but do not significantly hinder the passage of thermal radiation.
Fire resistance class F (EI): Translucent building elements, which also hinder the passage of thermal radiation according to DIN 4102 according to their fire resistance duration.
Flat glass is the generic term for all flat and curved panes, whether colourless or coloured. Also belonging to this category are for example hand blown or machined produced flat glass, float glass, ornamental glass, wired glass, garden clear glass, garden opaque glass, and profiled glass.
Float glass is the flat, transparent and uncoated base glass, which has parallel and fire polished surfaces. Made by pouring and flowing over a tin bath.
According to DIN EN 572-2 float glass exists as:
- Usual bright, uncoloured glass with a slight green intrinsic colour, which can become more apparent with increasing thickness,
- mass coloured glass
- very clear glass with low intrinsic colour (white glass)
- Borosilicate glass
Glass design brings transparent variety
There is a long tradition of using glass as part of furniture making. While in the past, glass products were an add-on, now they are undoubtedly an integral design element.
Glass doors, glass floors, tabletops, glass inserts are just a few examples of the ways glass products have become part of the design of contemporary, functional furniture. The incredible variety of decorative glass and mirrors has now been complemented by a wide range of fittings. Together with the options for glass processing and glass surface design, as well as new adhesive and sealing technology, they help turn creative ideas into furniture with aesthetic appeal. Tables, shelving units and audio furniture completely made from glass, or combined with aluminium or stainless steel frames or fittings are also growing in popularity.
Display with glass
Today, glass presentation technology has become a product area in its own right. Showcases have now become display cabinets, with a definite hint of furniture about them. The skilful interplay of glass and light shows precious exhibits and art or historical treasures at their best.
A condition for building a successful display cabinet is close cooperation between client, planner and glass specialist. Your ISOLAR® partner brings many years of experience working with glass, wood and metal, as well as the areas of safety, light and climate control. These are all an important foundation for the versatile design of rooms for presentation of exhibitions and products in companies and museums.
G
Depending on the type, degree of filling and mixing ratio, the gas filling in the cavity between the panes of insulating glass effects the optimised thermal protection.
The usability of non-regulated construction products and types are regulated by a general building inspectorate technical approval (abZ), which is issued by the German Institute for Construction Engineering (DIBt) on the basis of the State building regulations.
A general building inspectorate test certificate (abP) makes non-regulated building elements and designs generally applicable. The granting takes place on the basis of the State building regulations of approved inspection entities.
All materials used in glass products have their own raw material colours, which can be more pronounced with increasing thickness of the glass product. In order to meet the legal requirements with regard to energy saving, coated glasses are used. Even coated glasses have a natural colour. This intrinsic colour can be seen differently when looking through it and/or looking at it. Variations in the colour impression are possible and unavoidable due to the iron oxide content of the glass, the coating process, the coating itself as well as changes in the glass thicknesses and the pane structure.
Ideas made from glass for quality of life
Transparency and the interplay with light, openness and distance are what makes glass suitable for such a wide variety of applications.
Entrance areas, from the front door in private residences to reception areas in companies and public buildings, are more than just the interface between inside and outside. Glass is a defining element creating the first impression for any house, whether in the door panel, an automatic door or in the porch construction.
It would be difficult to imagine business centres and shopping arcades without glass assemblies and glass partition walls. Your ISOLAR® partner can support you in the planning phase and would be happy to take on the detailed measurements and installation.
Glass can also create new accents in the residential area. Attractive structures and decor underline the refined transparency of glass doors. They allow light to pass through, and if desired they can protect from prying eyes. The comprehensive range of fittings means they can be adapted to practically any surroundings.
Mirrors multiply an accomplished ambiance and reduce the problems of dark, secluded corners. There are no limits on the design of mirrors which are now available in any format imaginable - with and without lighting, with or without frames of all kinds, with engraving, grinding and bevels, with patterned surfaces, for example using sand blasting.
Glass is also firmly established in the bathroom and plumbing sector. Nothing can beat a real glass shower in terms of transparency, elegance and hygiene properties. In addition, there are mirrors, vanity units, shelves, etc.
Cutting, grinding, drilling for perfect glass refinement
Glass is unique, not just because of its transparency, but also because of its structure - it is the only non-crystalline, solid material. Therefore all glass processing techniques must be perfectly aligned with the particular properties of the material glass.
For perfect glass cutting, you also have to consider the features of the many different glass products. Digitally controlled cutting units and even high-tech applications such as water jet cutting techniques are used here.
Any chip removing techniques for grinding and drilling are out of the question when it comes to glass. Rather, tiny fragments of glass are blasted off and pulled off. Water must be used here for purposes of cooling and to take away the fragments removed. Bevels, fluted bevels, edge grinding, mitred edges, countersinking, drill holes of all kinds are just some examples of glass processing which can be carried out using these techniques. Surfaces which have become matt are made “crystal clear” once more using exhaustive polishing processes.
Cutting, grinding and drilling glass products is a requirement for later use in numerous applications.
Your ISOLAR® partner has access to all the available glass processing techniques based on their own manufacturing capability and integration into the ISOLAR® group.
H
The heat-soak test is the hot storage test for thermally toughened safety glass and serves to avoid so-called spontaneous breaks. In this hot air test, the tempered glass is exposed to a heat load of 290 °C for several hours in a special heat-soak oven. The test process is logged. The heat-soak test is mandatory, for example, for fall safe glazing made of thermally toughened safety glass and for thermally toughened safety glass facade panels.
I
These electromagnetic waves are not visible to the human eye, but are perceived as heat by the senses of feeling in humans. In the case of non-coloured glass, the transmittance in the infrared range of 780-2800 nm is very high.
In the case of insulating glass made of float glass, interference in the form of spectral colours can occur. Optical interference is the superposition of two or more light waves when they meet at a point. They are shown by more or less strong coloured zones, which change with pressure on the pane. This physical effect is enhanced by the plane parallelism of the glass surfaces. This plane parallelism ensures a distortion-free view. Interference phenomena are random and can not be influenced.
The subsequent installation of internal shading harbours the risk of heat build-up between shading and glazing in sun irradiation. The attachment of the shading is therefore to be done, with regard to the distance from the glazing and to the installation situation, in such a way that heat accumulation is avoided. If it is already known before the implementation of glazing that an internal shading is to be applied there, the use of thermally toughened safety glass may be recommended.
In the case of temperature changes, changes in the meteorological pressure and differences in the altitude between the place of installation and the place of manufacture, it can be assumed that the pressure in the cavity of an insulating glass unit will change.
L
Laminated glass consists of two or more glass layers, which are interconnected with one or more elastic intermediate layers. Laminated glass is produced and marked in accordance with the European Construction Products Regulation. The product properties and specification requirements are defined in DIN EN ISO 12543-1 to 12543-6. The factory production control and appropriate product labelling must be carried out in accordance with DIN EN ISO 14449.
Production
The majority of industrially produced laminated safety glass in Europe is processed with a polyvinyl butyral (PVB) film as an intermediate layer.
For this, the glass panes to be laminated are superimposed with the film as an intermediate layer. Subsequently, the panes are pressed together in press rollers at about 80° C with each other. The panes are still cloudy at this time to see through and lack the necessary adhesion between the glass and the composite film. Only in an autoclave at a pressure of 13 bar and a temperature of 130° Celsius the full adhesion between the surfaces is developed. The duration of the panes in the autoclave depends on the glass thicknesses and the number of glass panes to be laminated.
In rare cases, a thermoplastic (ionoplast) is used as an intermediate layer. This intermediate layer is usually processed in a composite bag. Glass with the ionoplastic interlayers are sealed in a vacuum bag. Subsequently, air is evacuated from the vacuum bag. In the autoclave at about 13 bar and 120° C the adhesion between the glass and the composite film is established.
The production of laminated glass products with Ethylene Vinyl Acetate Foils or cast resin interlayers is hardly relevant industrially.
Material properties
The properties of composite and laminated safety glass are diverse, but they change with the use of different materials. Accordingly, the ionoplastic interlayer is known for improving structural rigidity and remaining structural capacity. It is usually used there when there are increased structural requirements.
In order to increase the sound insulation, softer, specially developed PVB films are used.
There is also laminated glass, which serves to increase fire protection due to its swelling intermediate layers.
Laminated glass, with particularly tear resistant foils, are used for knock-through, breakthrough, bullet penetration and explosion resistant glazing.
By using coloured foils or laminating additional materials, laminated glass can be adapted to architectural requirements.
Due to widespread and standardised processing methods, the visual quality of laminated glass is generally very good. Only in rare cases are inclusions or optical distortions visible.
Far more frequently objected to are the so-called “delaminations”. In the case of delaminations the adhesion between the composite foil and the glass surface is missing. This can be seen in the form of bubbles between the glass panes. This may be due to a chemical incompatibility with adjacent building materials, an error of application or defective product quality. In most cases, several factors are critical to failure. Only rarely do delaminations have no immediate effect on the safety properties of the glass.
Application
Laminated safety glass is usually used where additional safety requirements have to be fulfilled. As the fall safeguarding of balconies, laminated safety glass serves as the direct protection of a person. In overhead applications, the use of laminated safety glass ensures that, in the case of glass breakage, no large glass elements fall on traffic areas below. To minimise the effects of explosions, explosion resistant glazing is also being installed in a growing number of construction projects.
The use of rigid composite films and multiple laminates are increasingly built in structurally load bearing glass elements. Examples of these include: Glass beams of glass columns. Also load bearing glass walls are installed in modern architecture.
Lead glazing usually consist of several individual, often coloured and/or painted on the surface, printed or processed glass. The individual glass pieces are assembled by lead profiles to form a unit.
For insulating glass with and without the use of coated surfaces, the light permeability depends significantly on the thickness of the individual panes used. The data provided in the tables for the light permeability of the insulating glass apply to individual glass thicknesses of 4 mm each for thermal insulating glass and 6 or 4 mm for solar protection glass. The percentages include a tolerance of ± 2 percentage points.
In the list of technical building regulations from the areas of construction law and plant safety for the planning, design and construction of structures or their parts, numerous technical rules are provided. Section §3 para. 3 of the Model Building Code or the corresponding section of the respective State Building regulations makes the list binding for each state.
The legal character of a specific technical rule changes as a result of the introduction as a technical building code. It no longer merely represents a recommendation, it must be observed within the scope of the relevant State building regulations.
To minimise energy losses today Low-E glass is used as standard. Low-E is an abbreviation for low-emissivity (low heat radiation) and defines an insulating glass with an applied wafer-thin metal layer of approx. 100 nm. This layer reduces the emissivity and serves as a warmth and/or sun protection layer.
M
A mechanical glass breakage is caused by short-term or long-term, dynamic or structural, mechanical point, line or surface load which is greater than the material properties of the glass (tensile and compressive strength).
When working with angle grinders, sandblasters, welding torches, etc., the pane surfaces must be protected by means of plaster or plastic panels against possible surface damage due to sparks or the like. When working near the pane, the surfaces must be protected against scratches, splashes, vapours, welding mist, etc. This is especially true for hot asphalt work on floors.
O
Opaque glass is formed by leaching alkali ions from the glass surface. Due to the damage of the glass structure, the glass becomes clouded on its surface. Temperature, humidity, exposure time and concentration of the acting medium influence this chemical process. The term opaque glass is also used to refer to cloudiness in insulating glass.
Light permeability
For insulating glass with and without the use of coated surfaces, the light permeability depends significantly on the thickness of the individual panes used. The data provided in the tables for the light permeability of insulating glass apply to individual glass thicknesses of 4 mm each for thermal insulating glass and 6 or 4 mm for solar protection glass. The percentages include a tolerance of ± 2 percentage points.
Total energy transmittance
The total energy transmittance (g-value) of insulating glass depends essentially on the thickness of the individual panes used. This applies in particular to the thickness of the outer pane. There are building regulations in Germany for the determination of the total energy transmittance of multi-pane insulating glass depending on the glass thickness. The data for the total energy transmittance of ISOLAR glass given in the tables refer to individual glass thicknesses of 4 mm each (thermal insulating glass, sound insulating glass) and 6 or 4 mm (solar protection glass), in each case in conjunction with the building regulations. The percentages include a tolerance of ± 2 percentage points.
Intrinsic colour
All materials used in glass products have their own raw material colours, which can be more pronounced with increasing thickness of the glass product. In order to meet the legal requirements with regard to energy saving, coated glasses are used. Even coated glasses have a natural colour. This intrinsic colour can be seen differently when looking through it and/or looking at it. Variations in the colour impression are possible and unavoidable due to the iron oxide content of the glass, the coating process, the coating itself as well as changes in the glass thicknesses and the pane structure.
Colour impression
The colour impression of insulating glass can also be described with the help of physical characteristics. The reflection colours are characterised by viewing from the outside and when viewing from the inside, as well as the colours when looking through from the outside to the inside and from the inside to the outside. In the case of all four colour impressions to be mentioned, the physical perception as well as the subjective perception of the human eye are of importance. The latter is also heavily dependent on the influences dominated by the respective light and/or lighting conditions. All the aforementioned colour impressions are subject to the fluctuations which are possible in ongoing production. Absolute colour uniformity is therefore not always possible, especially with coated glasses. In particular, colour deviations can not be ruled out when using coated glasses of different origin in the same building as well as for subsequent deliveries and retrofitting of insulating glass with coated surfaces.
P
Subsequent application of foils and colours to glazing generally results in an additional high thermal load on the glass when exposed to sun irradiation. In particular, when it comes to strongly absorbent foils and colours, the thermal stress of the glass generated by sun irradiation can reach a considerable amount. Due to the expected local temperature difference or heat build-up in sun irradiation, high stresses develop in the glass, which can lead to breakage or cracks in the glass.
If it is already known in the planning phase of a building that adhesives or paint will be used on the windows (for example kindergartens), the windows can be made of thermally toughened safety glass. Thermally toughened safety glass, as pre-stressed glass, can withstand significantly higher thermal loads than the float glass normally used. The risk of breakage is significantly reduced.
It is also to be considered which direction the respective panes are facing. The decisive factor is the question of whether such panes are exposed to vertical or almost vertical sun irradiation. In that case the thermal load is greatest.
Therefore, it is highly recommended to consult a specialist before using adhesives or paint on the glazing units.
Glass surfaces must be professionally and properly cleaned according to their degree of soiling. For this purpose, in particular a sufficient amount of clean water is to be used.
Other methods of glass cleaning should only be considered if the use of much clean water is not sufficient. However, aggressive cleaning agents (for example, alkaline detergents, hydrofluoric acid and fluoride containing detergents) must be avoided because they irreparably damage the glass or the glass surfaces.
Cement sludges and all other secretions of building materials are to be removed immediately, because even then the glass surfaces can be irreparably damaged or later damage to the glass can be caused.
Scratching tools, razor blades and scrapers are not suitable because they can cause scratch marks in the surfaces. In particular, so-called “blading” is not a proper method for cleaning entire glass surfaces.
For multi-pane insulating glass with coated outer surface special cleaning regulations apply.
“Normal” contaminants are to be removed as just described, however, no abrasive cleaning material, e.g. abrasive or commercial steel wool, can be used.
Persistent soiling, e.g. paint or tar splashes or adhesive residues should be treated with suitable solvents, e.g. alcohol, acetone or benzine, dissolved and then cleaned. When cleaning with solvents, care must be taken not to damage seals or other organic materials.
For soiling that can not be eliminated with the cleaning measures described above, please contact your ISOLAR® Glass Partner.
When heated by 50 °C, a glass with an edge length of 1 m expands by about 0.5 mm. This “thermal expansion” is not critical when the glass is evenly heated.
It is quite different if the glass is not heated evenly: Then some areas of the pane expand more, others less strongly. This results in stresses in the glass. These “thermal” stresses are greater the larger the difference in temperature in the glass becomes.
Float glass “tolerates” temperature differences of about 40°C. If uneven heating produces a higher temperature difference, breakage of glass is to be expected. Often one part of a pane of glass is exposed to direct sunlight, while another part is in the shade. Such "partially shaded" glass will always be heated unevenly.
The size of the tensions generated by the partial shading in the glass depends on a number of circumstances. Such factors include:
- Intensity of the sun irradiation,
- pane format and installation situation,
- geometric distribution of the glass surface portions in the sun and in the shade,
- Absorption of sun irradiation.
Increased absorption is mainly due to coated and coloured glass. For glass that is subject to heavy exposure due to partial shading, the use of thermally toughened safety glass may be a suitable preventive measure.
If one day you find that despite your new windows and new heat insulation glass condensation forms on the windows and the walls may feel more damp than before, then this has quite natural causes: Your old windows were
never completely tight. This had the “advantage” of having a regular “automatic” air exchange.
Visible water vapour from the kitchen and bathroom, but also the invisible release of moisture by humans (alone, when sleeping, a person releases about ¾ litres of moisture in 8 hours) was able to escape through this “forced ventilation”. The disadvantage was, of course, a high heat loss and useless heating energy consumption.
Do you have to put up with humidification in exchange for the better heat insulation and the new windows? No! You should follow these tips:
- Ventilate all rooms in the morning for 20 to 30 minutes, especially in dry weather.
- During the day, ventilate the rooms three to four times for 10 to 15 minutes, depending on use.
- During this ventilation, the windows should be wide open.
If such a shock ventilation is not possible, you should provide fresh air via the adjustable ventilation option (e.g. tilt position), which should be present on your windows.
What’s more: Cold air can absorb less humidity than warm air. Therefore, even in foggy weather moisture from the warm room is “ventilated” out. Those who follow these tips have fewer moisture problems or “sweaty windows”. In addition, you do something for a healthy living environment and save a lot of heating energy, thanks to tightly closing windows and the heat insulating glass.
PVB is an abbreviation for polyvinyl butyral. The material is used as a viscoplastic intermediate foil (0.38 mm) for laminated safety glass. To increase the residual capacity, you can use several foils.
R
Radiation transmittance is the ratio of the total radiant energy transmitted by the glazing (perpendicular to the surface) to the incident radiant energy.
A minimum distance of 30 cm must always be observed between radiators and insulating glass behind it. When using thermally toughened safety glass as the inner pane of the insulating glass, the minimum distance can be reduced to 15 cm. It is recommended to ensure that the radiator and the insulating glass are the same width, as this leads to a more uniform heating of the glass. If the above distances are not complied with, radiation protection must be installed.
After determining the sound reduction index R for specified frequencies, the weighted sound reduction index Rw is calculated in accordance with DIN EN ISO 717-1. It is expressed in the unit of measure decibel (dB). For this purpose, the R values determined by measurement are compared with reference values according to EN 717-1. The reference curve is shifted vertically parallel to the ordinate in the measurement diagram in accordance with EN 717-1 until the undershoot of the measurement curve is on average no more than 2 dB. In this case, exceedances are not taken into account. The ordinate value of the shifted reference curve at 500 Hz corresponds to the weighted sound reduction index Rw (so-called “single value”).
S
The product range of security glazing serves to protect people and buildings against attacks and break-ins of all kinds. The production process for bonding the glass and plastic as well as the construction of the bonded panes are specially adapted for the nature of the expected attack. Depending on the expected types of attack, the glass is subjected to different tests.
Test procedure
Impact-resistant glazing of resistance class PAare tested with ball drop tests. The loads correspond to those that are generated by the impact of something heavy thrown at it. Class P1A-P4A is divided into different heights of the 4.11 kg metal ball and the number of ball drop tests (P5A).
Break resistant glazing of resistance class PB is tested with an axe machine. This test simulates the loads when attacking glass with an impact tool that can cut. Classifications P6B-P8B are based on the number of impacts used to create an opening of 40 x 40 cm in the glass.
Bullet resistant glazing of resistance class BR/SG is tested in a shooting test. This involves firing a total of three rounds at each pane. The classification BR1-BR7 and SG1-SG is carried out according to different weapons, calibres and shooting distances.
Explosion-resistant glazing of the resistance class ER serves as protection against explosions. It is recommended to check the complete construction according to the standards and norms provided for this purpose.
Semi-tempered glass consists of a monolithic float glass which is thermally treated to increase flexural strength. Semi-tempered glass is produced and labelled in accordance with the European Construction Products Regulation. The product properties and specification requirements are defined in DIN EN ISO 1863-1. The factory production control and appropriate product labelling must be carried out in accordance with DIN EN ISO 1863-2.
Production
As with thermally tempered safety glass, the cut glass pane is heated above the transformation temperature as with semi-tempered glass. To avoid possible marks and deformations of the softening glass, the glass pane is continuously moved back and forth over rollers in the oven. The homogeneously heated glass is then cooled in a controlled manner. The cooling rate is lower compared to the thermally toughened safety glass process, resulting in a lower pre-stressing.
Material properties
The compressive stress created on the surfaces increases the flexural strength of semi-tempered glass, which can withstand up to 3 times higher loads.
The fracture pattern is similar to that of untreated float glass. Simplified, it can be said that it breaks radiantly from the starting point into large fragments. Due to the frozen pre-stressing, semi-tempered glass can not be subsequently processed.
If the pre-stressing introduced is uneven, a point shaped or stripe pattern can be detected under certain lighting conditions. To detect this, a high proportion of polarised radiation must be present in the light. Polarised light can be of natural origin or is created by reflection from adjacent surfaces. However, the risk of undesired anisotropies is significantly reduced by the lower pre-stressing level. With modern production know-how these phenomena can be additionally reduced.
As the glass panes are heated above the transformation temperature (softening temperature) during production, they lose their planarity. The “wavy glass surface” creates visual distortions in the viewer and reflection. According to the current standard, the wave depth of 0.30 mm must not be exceeded over a distance of 300 mm. These geometric limits are not sufficient to describe the actual optical quality of the glass. Only when the actual wavelength is directly related to the wave depth can a statement about the optical quality be made.
Millidiopters allow a meaningful description of the optical quality. The wave length and wave depth are thereby evaluated together. The following table shows the resulting millidiopters, depending on the wavelength and wave depth.
| Wave depth / wavelength [mm] | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
/ | 80.00 | 100.00 | 120.00 | 140.00 | 160.00 | 180.00 | 200.00 | 220.00 | 240.00 | 260.00 | 280.00 | 300.00 | 320.00 | 340.00 | 360.00 | 380.00 |
0.01 | 61.69 | 39.48 | 27.42 | 20.14 | 15.42 | 12.18 | 9.87 | 8.16 | 6.85 | 5.84 | 5.04 | 4.39 | 3.86 | 3.42 | 3.05 | 2.73 |
0.02 | 123.37 | 78.96 | 54.83 | 40.28 | 30.84 | 24.37 | 19.74 | 16.31 | 13.71 | 11.68 | 10.07 | 8.77 | 7.71 | 6.83 | 6.09 | 5.47 |
0.03 | 185.06 | 118.44 | 82.25 | 60.43 | 46.26 | 36.55 | 29.61 | 24.47 | 20.56 | 17.52 | 15.11 | 13.16 | 11.57 | 10.25 | 9.14 | 8.20 |
0.04 | 246.74 | 157.91 | 109.66 | 80.57 | 61.69 | 48.74 | 39.48 | 32.63 | 27.42 | 23.36 | 20.14 | 17.55 | 15.42 | 13.66 | 12.18 | 10.94 |
0.05 | 308.43 | 197.39 | 137.08 | 100.71 | 77.11 | 60.92 | 49.35 | 40.78 | 34.27 | 29.20 | 25.18 | 21.93 | 19.28 | 17.08 | 15.23 | 13.67 |
0.06 | 370.11 | 236.87 | 164.49 | 120.85 | 92.53 | 73.11 | 59.22 | 48.94 | 41.12 | 35.04 | 30.21 | 26.32 | 23.13 | 20.49 | 18.28 | 16.40 |
0.07 | 431.80 | 276.35 | 191.91 | 140.99 | 107.95 | 85.29 | 69.09 | 57.10 | 47.98 | 40.88 | 35.25 | 30.71 | 26.99 | 23.91 | 21.32 | 19.14 |
0.08 | 493.48 | 315.83 | 219.32 | 161.14 | 123.37 | 97.48 | 78.96 | 65.25 | 54.83 | 46.72 | 40.28 | 35.09 | 30.84 | 27.32 | 24.37 | 21.87 |
0.09 | 555.17 | 355.31 | 246.74 | 181.28 | 138.79 | 109.66 | 88.83 | 73.41 | 61.69 | 52.56 | 45.32 | 39.48 | 34.70 | 30.74 | 27.42 | 24.61 |
0.10 | 616.85 | 394.78 | 274.16 | 201.42 | 154.21 | 121.85 | 98.70 | 81.57 | 68.54 | 58.40 | 50.36 | 43.86 | 38.55 | 34.15 | 30.46 | 27.34 |
0.11 | 678.54 | 434.26 | 301.57 | 221.56 | 169.63 | 134.03 | 108.57 | 89.72 | 75.39 | 64.24 | 55.39 | 48.25 | 42.41 | 37.57 | 33.51 | 30.07 |
0.12 | 740.22 | 473.74 | 328.99 | 241.70 | 185.06 | 146.22 | 118.44 | 97.88 | 82.25 | 70.08 | 60.43 | 52.64 | 46.26 | 40.98 | 36.55 | 32.81 |
0.13 | 801.91 | 513.22 | 356.40 | 261.85 | 200.48 | 158.40 | 128.30 | 106.04 | 89.10 | 75.92 | 65.46 | 57.02 | 50.12 | 44.40 | 39.60 | 35.54 |
0.14 | 863.59 | 552.70 | 383.82 | 281.99 | 215.90 | 170.59 | 138.17 | 114.19 | 95.95 | 81.76 | 70.50 | 61.41 | 53.97 | 47.81 | 42.65 | 38.28 |
0.15 | 925.28 | 592.18 | 411.23 | 302.13 | 231.32 | 182.77 | 148.04 | 122.35 | 102.81 | 87.60 | 75.53 | 65.80 | 57.83 | 51.23 | 45.69 | 41.01 |
0.16 | 986.96 | 631.65 | 438.65 | 322.27 | 246.74 | 194.96 | 157.91 | 130.51 | 109.66 | 93.44 | 80.57 | 70.18 | 61.69 | 54.64 | 48.74 | 43.74 |
0.17 | 1048.65 | 671.13 | 466.06 | 342.41 | 262.16 | 207.14 | 167.78 | 138.66 | 116.52 | 99.28 | 85.60 | 74.57 | 65.54 | 58.06 | 51.78 | 46.48 |
0.18 | 1110.33 | 710.61 | 493.48 | 362.56 | 277.58 | 219.32 | 177.65 | 146.82 | 123.37 | 105.12 | 90.64 | 78.96 | 69.40 | 61.47 | 54.83 | 49.21 |
0.19 | 1172.02 | 750.09 | 520.90 | 382.70 | 293.00 | 231.51 | 187.52 | 154.98 | 130.22 | 110.96 | 95.67 | 83.34 | 73.25 | 64.89 | 57.88 | 51.95 |
0.20 | 1233.70 | 789.57 | 548.31 | 402.84 | 308.43 | 243.69 | 197.39 | 163.13 | 137.08 | 116.80 | 100.71 | 87.73 | 77.11 | 68.30 | 60.92 | 54.68 |
0.21 | 1295.39 | 829.05 | 575.73 | 422.98 | 323.85 | 255.88 | 207.26 | 171.29 | 143.93 | 122.64 | 105.75 | 92.12 | 80.96 | 71.72 | 63.97 | 57.41 |
0.22 | 1357.07 | 868.53 | 603.14 | 443.13 | 339.27 | 268.06 | 217.13 | 179.45 | 150.79 | 128.48 | 110.78 | 96.50 | 84.82 | 75.13 | 67.02 | 60.15 |
0.23 | 1418.76 | 908.00 | 630.56 | 463.27 | 354.69 | 280.25 | 227.00 | 187.60 | 157.64 | 134.32 | 115.82 | 100.89 | 88.67 | 78.55 | 70.06 | 62.88 |
0.24 | 1480.44 | 947.48 | 657.97 | 483.41 | 370.11 | 292.43 | 236.87 | 195.76 | 164.49 | 140.16 | 120.85 | 105.28 | 92.53 | 81.96 | 73.11 | 65.62 |
0.25 | 1542.13 | 986.96 | 685.39 | 503.55 | 385.53 | 304.62 | 246.74 | 203.92 | 171.35 | 146.00 | 125.89 | 109.66 | 96.38 | 85.38 | 76.15 | 68.35 |
0.26 | 1603.81 | 1026.44 | 712.80 | 523.69 | 400.95 | 316.80 | 256.61 | 212.07 | 178.20 | 151.84 | 130.92 | 114.05 | 100.24 | 88.79 | 79.20 | 71.08 |
0.27 | 1665.50 | 1065.92 | 740.22 | 543.84 | 416.37 | 328.99 | 266.48 | 220.23 | 185.06 | 157.68 | 135.96 | 118.44 | 104.09 | 92.21 | 82.25 | 73.82 |
0.28 | 1727.18 | 1105.40 | 767.64 | 563.98 | 431.80 | 341.17 | 276.35 | 228.39 | 191.91 | 163.52 | 140.99 | 122.82 | 107.95 | 95.62 | 85.29 | 76.55 |
0.29 | 1788.87 | 1144.87 | 795.05 | 584.12 | 447.22 | 353.36 | 286.22 | 236.54 | 198.76 | 169.36 | 146.03 | 127.21 | 111.80 | 99.04 | 88.34 | 79.28 |
0.30 | 1850.55 | 1184.35 | 822.47 | 604.26 | 462.64 | 365.54 | 296.09 | 244.70 | 205.62 | 175.20 | 151.07 | 131.59 | 115.66 | 102.45 | 91.39 | 82.02 |
Application
Semi-tempered glass is always used when there are increased structural requirements and the flexural strength of float glass is insufficient.
The field of application of semi-tempered glass is superimposed with that of thermally toughened safety glass. It is necessary for large area glass elements, which are exposed to high wind loads or structural load bearing elements, such as in glass walls, glass beams and glass columns. Semi-tempered glass is also used for point-fixed glazing where stress concentrations are to be expected in the hole area. Although semi-tempered glass has lower flexural strength compared to safety glass, it is an important component in modern glass construction. The advantage lies in the increased residual capacity of the product. If it is installed in laminated glass, the result is a high load capacity despite any breakage of glass. This leaves enough time to undertake the necessary exchange measures.
Often, semi-tempered glass is also used when the expected temperature differences in a glass element lead to an increased risk of breakage.
Further details on the optical evaluation of the glass surface in Millidiopters can be found in the American standard ASTM C 1651.
In recent years, the network of so-called base stations for various mobile networks has become increasingly dense. So at the same time, the question of many people becomes ever more urgent:
Can I protect myself from unwanted “mobile phone radiation”?
An extensive study commissioned by the Free State of Bavaria has now dealt with “measures in buildings to shield electromagnetic waves”.
Which measures are suitable against which type of radiation depends strongly on the frequency of the respective waves. For “mobile phone radiation” (D-network, E-network, UMTS), these frequencies are between about 400 MHz and about 2.2 GHz.
The so-called “shielding materials” work by partly reflecting and partly absorbing electromagnetic waves. The “shielding” is indicated in % as “shield attenuation” in decibels (dB) or as “shield efficiency”. A shield attenuation of 20 dB means a reduction of the “power flow density” to 1% or a shield efficiency of 99%.
The highly thermal insulating coating in heat insulating glass reflects the waves of D and E networks by about 99.9%. Thermal insulation glass therefore has a screen attenuation of about 30 dB for those frequencies. Thermal insulating glass thus helps to save energy and protect against unwanted “mobile phone radiation”.
When opening sliding doors and windows, an additional space is formed between the glazed elements. If sliding doors and windows are to be equipped with insulating glass using coatings or other glass products that absorb the sun irradiation more intensely, ensure that there is sufficient ventilation in this gap. If sufficient ventilation is not ensured, there is a risk of heat build-up with thermally induced pane breakage. In this case, therefore, the preventive use of thermally toughened safety glass is recommended.
Sound refers to mechanical vibrations and waves that propagate in the air, in water and in any other medium. These vibrations or waves are perceived by the human ear in the range of 16-16,000 Hertz. Sound propagating through solids is called structure-borne noise, e.g. sound produced by walking is “impact sound”. This structure-borne sound is audible when it is emitted as airborne sound.
Frequency (f) and Hertz (Hz)
The frequency indicates the number of oscillations of the sound wave per second. High, shrill tones have a high frequency (many oscillations in the unit of time), deep, dull tones have a low frequency (few oscillations in the unit of time).
The unit of measurement of the frequency is “Hertz (Hz)”, where 1 Hz means “one oscillation per second”.
Decibel (dB)
is the abbreviation for decibels (1 dB = 1/10 Bel; the Bel was named after Graham Bell, the inventor of the electromagnetic telephone). It is a dimensionless unit of logarithmic physical quantities, which are then called levels. In sound engineering, airborne and structure-borne sound levels are given in dB.
Rated sound reduction index (Rw)
After determining the sound reduction index R for specified frequencies, the weighted sound reduction index Rw is calculated in accordance with DIN EN ISO 717-1. It is expressed in the unit of measure decibel (dB). For this purpose, the R values determined by measurement are compared with reference values according to EN 717-1. The reference curve is shifted vertically parallel to the ordinate in the measurement diagram in accordance with EN 717-1 until the undershoot of the measurement curve is on average no more than 2 dB. In this case, exceedances are not taken into account. The ordinate value of the shifted reference curve at 500 Hz corresponds to the weighted sound reduction index Rw (so-called “single value”).
Spectrum adaptation
In order to take into account the different frequency spectra of residential and traffic noise, so-called spectrum adaptation values C and Ctr for the building acoustics range of 100-3150 Hz were introduced in accordance with DIN EN ISO 717-1. They are used to adjust the weighted sound reduction index over a frequency range of 100-3150 Hz. The spectrum adaptation values C100-5000 and Ctr100-5000 additionally take into account the spectrum in the frequency range of 100-5000 Hz. The spectrum adjustment values are product properties that result from the measured sound absorption curve of the glass products, taking into account the relevant noise sources.
A spacer profile ensures the minimum distance between two pane surfaces. These profiles are usually made of metal, plastic or organic materials.
The span is the distance between the calculated bearing points. For 2-sided support, the span corresponds to the unsupported free edge length of panes. With 4-sided support, it corresponds to the short edge length. Structurally, the span corresponds to the glass outside dimension.
Radiators in front of glass
A minimum distance of 30 cm must always be observed between radiators and insulating glass behind it. When using thermally toughened safety glass as the inner pane of the insulating glass, the minimum distance can be reduced to 15 cm. It is recommended to ensure that the radiator and the insulating glass are the same width, as this leads to a more uniform heating of the glass. If the above distances are not complied with, radiation protection must be installed.
Sliding doors and windows
When opening sliding doors and windows, an additional space is formed between the glazed elements. If sliding doors and windows are to be equipped with insulating glass using coatings or other glass products that absorb the sun irradiation more intensely, ensure that there is sufficient ventilation in this gap. If sufficient ventilation is not ensured, there is a risk of heat build-up with thermally induced pane breakage. In this case, therefore, the preventive use of thermally toughened safety glass is recommended.
Internal shading
The subsequent installation of internal shading harbours the risk of heat build-up between shading and glazing in sun irradiation. The attachment of the shading is therefore to be done, with regard to the distance from the glazing and to the installation situation, in such a way that heat accumulation is avoided. If it is already known before the implementation of glazing that an internal shading is to be applied there, the use of thermally toughened safety glass may be recommended.
Adhesives and painting on glass
The subsequent application of absorbent foils and colours leads to a strong thermal load of the glass with solar irradiation with the risk of thermally induced pane breakage. If it is already known before the implementation of glazing that such foils and paints are to be applied there, the use of thermally toughened safety glass is recommended in order to reduce the risk of breakage.
Partially shaded glass
An increased thermal load is also generated for glass when one part of the pane is exposed to direct sun while another part is in the shade. Such partially shaded glass is heated unevenly. The stresses in the glass caused by the uneven heating depend, among other things, on the intensity of the sun irradiation, the absorption of sun irradiation by the glass and the geometric distribution of the sunny and shaded glass surface portions. Glass products with increased absorption of sun irradiation are in particular coated and/or volume-coloured glass. If it is already known before the implementation of glazing that partial thermal shading produces strong thermal loads on the intended glass, it is recommended to test the use of thermally toughened safety glass in individual cases in order to reduce the risk of breakage.
In order to take into account the different frequency spectra of residential and traffic noise, so-called spectrum adaptation values C and Ctr for the building acoustics range of 100-3150 Hz were introduced in accordance with DIN EN ISO 717-1. They are used to adjust the weighted sound reduction index over a frequency range of 100-3150 Hz. The spectrum adaptation values C100-5000 and Ctr100-5000 additionally take into account the spectrum in the frequency range of 100-5000 Hz. The spectrum adjustment values are product properties that result from the measured sound absorption curve of the glass products, taking into account the relevant noise sources.
Stepped insulating glass refers to an insulating glass unit in which the outer pane has a pane projection at one or more edges. This glass is suitable for use in the roof area or in special frame structures.
Stickers and labels on insulating glass have a special adhesive that is particularly suitable for this purpose. They should be removed from the glass pane as quickly as possible. In particular, the stickers should not be exposed to sun irradiation for a long time. A different wetting reaction is not entirely avoidable with regard to the rest of the glass surface at the spots where stickers and labels were removed. Cork pads can also leave residues on glass surfaces or change the wetting reaction of the glass surfaces. They are therefore also to be removed as soon as possible.
Insulating glass must not be set down on a corner or edge. Likewise, the windows must never be placed on hard surfaces such as concrete or stone floors. Even minor damage to the glass edges can later be the cause of glass cracks. For this reason, insulating glass should always be placed on wood or a firm plastic base, whereby area separation (at least 3 mm) and low inclination (about 6 degrees) should be ensured. All units are to be supported.
Protect against moisture
In the case of glass panels lying on each other, moisture leads to surface chemical reactions such as leaching. As a result, visible damage to the glass surfaces can occur within a short time. The glass must therefore be stored and transported according to the moisture present.
Protection against heat radiation
Glass packages stored outside absorb the rays of the sun much more than single panes. Strong, uneven heating occurs in the glass stack. As a result, glass breakage due to thermal overload and damage to the edge seal are possible. Especially endangered in the stack are coloured and coated glasses, ornamental and wire glasses. Such glass packages must therefore be protected from direct sun irradiation and, if necessary, stored in dry, well ventilated rooms. It is also recommended to loosen and remove any packing clamps after settling down in the storage location.
Protect from UV radiation
Insulating glass stored outdoors must not be exposed to sun irradiation because the “normal” edge seal is not UV-resistant and the surface of the edge seal can be damaged by UV radiation. If, however, panes have to be stored outdoors, they must be protected against UV radiation by covering with non-transparent foils or the like. Insulating glass, whose edge seal should be permanently exposed to direct sun irradiation, are to be designed with a UV-resistant edge seal.
Modern architecture with fully glazed facades
Fully glazed facades have had a considerable influence on glass architecture in line with the principle of “Structural glazing”. This designation describes a facade construction technique whereby the glass is only attached to the load-bearing construction using a silicone adhesive.
Structural glazing facades represent the greatest challenge to the selection and processing of the facade glazing as well as the sealants and adhesives. The structural joining of the glass to the system profiles should only be carried out by specially authorised, supervised companies. Therefore, close collaboration between the architect, facade builder and glass specialist is absolutely imperative.
Nowadays, there are also similar systems for external facade systems which function without structural joints.
When it comes to “Structural glazing”, ISOLAR® can supply a comprehensive range of services from individual consultation, production of the special glass required, right up to any structural bonding of units in appropriately authorised companies.
When heated by 50 °C, a glass with an edge length of 1 m expands by about 0.5 mm. This “thermal expansion” is not critical when the glass is evenly heated.
It is quite different if the glass is not heated evenly: Then some areas of the pane expand more, others less strongly. This results in tensions in the glass. These “thermal” stresses are greater the larger the difference in temperature in the glass becomes. Float glass “tolerates” temperature differences of about 40°C. If uneven heating produces a higher temperature difference, breakage of glass is to be expected.
Often one part of a pane of glass is exposed to direct sunlight, while another part is in the shade. Such "partially shaded" glass will always be heated unevenly.
The size of the tensions generated by the partial shading in the glass depends on a number of circumstances. Such factors include:
- Intensity of sun irradiation,
- pane format and installation situation,
- geometric distribution of the glass surface portions in the sun and in the shade.
- Absorption of sun irradiation.
Increased absorption is mainly due to coated and coloured glass. For glass that is subject to heavy exposure due to partial shading, the use of thermally toughened safety glass may be a suitable preventive measure.
The effectiveness of sun protection glazing is described with a whole series of key figures. The most important ones are:
Light transmission (LT in %)
It indicates the proportion of sun irradiation in the range of visible light (380 - 780 nm) that passes directly through the glazing.
Total energy transmittance (g in %)
It indicates what proportion of the total solar irradiation (300 - 2500 nm) is energetically usable behind glazing. It is the sum of direct and indirect radiation transmission.
Heat transfer coefficient (U value in W/m²K)
It is a measure of the heat loss through glazing. The lower the U value, the better the heat insulation.
Selectivity index (S)
It indicates how well a glazing can separate visible light
from infrared radiation, S = LT / g.
Shading coefficient (b-factor, b)
It is an arithmetic variable needed for the calculation of cooling loads according to VDI Guideline 2078, b = g / 0.8.
Light reflectance (LR in %)
It indicates the proportion of sun irradiation in the range of visible light (380 - 780 nm) that is reflected from outside with incidence of light. The larger the LR, the more reflective the effect of the glass is.
Colour rendering index Ra
The colour rendering characteristics of the daylight transmitted are described by the general colour rendering index Ra. The reference illuminant is D65 or the radiation of the most similar colour temperature.
Radiation transmittance
Radiation transmittance is the ratio of the total radiant energy transmitted by the glazing (perpendicular to the surface) to the incident radiant energy.
Design and glass: the ideal combination for a brilliant statement
Matt makes a fine impression
Flooded with light yet not see-through - that’s the effect of matt glass. Sand blasting and etching are the two techniques used for matting. They differ from each other in terms of depth and fineness of the structure. Glass surfaces can be processed across part of or the whole area using both approaches. There are practically no limits to the creativity used when designing patterns.
Art & glass
Glass screen printing techniques have developed very quickly in recent years. Ceramic colour is applied to the surface through screen masking, and then permanently thermally bonded to the glass. Whether over the whole surface or just a part of it, there are practically no limits on your imagination. Using a wide variety of colours, you can create a harmonious entity or create deliberate contrasts. This means you can bring your own, individual patterns, lettering and company logos to life.
All designers know that screen printing allows them to transpose their artistic creations onto glass. This connection of art and glass creates a completely new feel. Allow the interplay of colours and transparency to seduce you.
Lead and art glazing
This traditional technique represents another option for decorative and artistic creations using glass. In close collaboration with you, your ISOLAR® partner will make your ideas a reality, and will protect your lead and art glazing by building it into insulating glass.
T
The heat transfer coefficient (U value in W/m²K) is a measure of the heat loss through glazing. It indicates the amount of warmth passing through the facade element in the state of equilibrium per unit time, per unit area and per unit of the temperature difference between the two sides of the facade element. This means that the U value is a measure of how much heat output flows from warm to cold at a temperature difference of 1 K (Kelvin).
Today's U-values are around 1.1 W / m²K (double heat insulation glass) and 0.6 W / m²K (triple heat insulation glass). It is always the case: The lower the U value, the better the heat insulation.
(Ug) U-Value:
The small g expresses that the value applies only to the glazing. The U-Value of insulating glass depends on the thermal insulation coating, the type of gas filling, the degree of gas filling and the gap between the panes.
Thermally toughened safety glass consists of a monolithic float glass pane, which is tempered by a thermal treatment. This increases the flexural strength and creates a characteristic fracture pattern. Thermally toughened safety glass is produced and marked in accordance with the European Construction Products Regulation. The product properties and specification requirements are defined in DIN EN ISO 12150-1. The factory production control and appropriate product labelling must be carried out in accordance with
DIN EN ISO 12150-2. For heat-soaked thermally toughened safety glass, DIN EN 14179 applies.
Production
At the beginning of the production of thermally toughened safety glass, also called tempered safety glass, the previously cut glass pane is heated above the transformation temperature (softening temperature). To avoid possible marks and deformations of the softening glass, the glass pane is continuously moved back and forth over rollers in the oven. The homogeneously heated glass is then rapidly cooled by a blower. The glass surface cools immediately and solidifies, while the glass core slowly loses temperature and the molecules have more time to structure. The result is a compressive stress on the glass surfaces and a tensile stress in the glass core.
Material properties
The pre-stressing introduced, significantly changes the properties of the original float glass. The compressive stress developed on the surfaces increases the flexural strength of the glass pane. This allows thermally toughened safety glass to withstand up to 5 times higher loads.
If the glass surface is damaged or the bending tensile strength is exceeded, the glass pane breaks up immediately. The frozen pre-stressing is released suddenly. This leads to a high crack propagation speed, which manifests itself in a small-crumbed fracture pattern. These “break crumbs” are described as blunt edged. Together with the low mass of the individual crumb, this results in a certain safety property.
Due to the frozen pre-stressing, toughened safety glass can not be subsequently processed.
If the pre-stressing introduced is uneven, a point shaped or stripe pattern can be detected under certain lighting conditions. To detect this, a high proportion of polarised radiation must be present in the light. Polarised light can be of natural origin or is created by reflection from adjacent surfaces. These so-called anisotropies, which can be recognised in the glass, do not constitute a product defect according to the current standard (DIN EN ISO 12150). With modern production know-how these appearances can be minimised so that they are barely perceptible.
Another material property of thermally toughened safety glass is the increased risk of spontaneous breakage. In the process, contamination (nickel sulphide, NiS) of the molten glass leads to microscopic inclusions. Under certain circumstances, these inclusions can grow and cause the glass to break unexpectedly. To reduce the risk of spontaneous breakage, the glass can be subjected to a hot storage test. In this the glass panes are heated to over 280° Celsius for four hours. This reduces the risk of spontaneous breakage to a minimum.
As the glass panes are heated above the transformation temperature (softening temperature) during production, they lose their planarity. The “wavy glass surface” creates visual distortions in the viewer and reflection. According to the current standard, the wave depth of 0.30 mm must not be exceeded over a distance of 300 mm. These geometric limits are not sufficient to describe the actual optical quality of the glass. Only when the actual wavelength is directly related to the wave depth can a statement about the optical quality be made.
Millidiopters allow a meaningful description of the optical quality. The wave length and wave depth are thereby evaluated together. The table at the end of this Isolas compass shows the resulting millidiopters depending on the wavelength and wave depth.
Application
Thermally toughened safety glass is always used when there are increased safety features or increased structural requirements.
The increased safety properties of thermally toughened safety glass are based on the assumption that the small crumbly fracture pattern with “blunt” breaklines does not present a great risk of injury. Therefore, thermally toughened safety glass can be used as a partition wall for example.
Although the glass breaks up into small crumbs, the fragments still cling together in clod-shaped islands. The risk of injury is increased if the glass can fall onto traffic areas.
The compressive stress applied on the glass surfaces increases the flexural strength of the glass. Very often you need thermally toughened safety glass for large glass elements, which are exposed to high wind loads. Even with structural load bearing elements, such as glass walls, glass beams or glass columns, the increased strength is an advantage. This also applies to point-fixed glazing, where a concentration of stress can be expected in the hole area.
Often, thermally toughened safety glass is also used when the expected temperature differences in a glass element lead to an increased risk of breakage.
The total energy transmittance (g in%) of insulating glass indicates
what proportion of the total sun irradiation (300 - 2500 nm) is energetically usable behind the glazing. It is the sum of direct and indirect radiation transmission.
The g-value depends essentially on the thickness of the individual panes used. This applies in particular to the thickness of the outer pane. There are building regulations in Germany for the determination of the total energy transmittance of multi-pane insulating glass depending on the glass thickness. The data for the total energy transmittance of ISOLAR glass given in the tables refer to individual glass thicknesses of 4 mm each (thermal insulating glass, sound insulating glass) and 6 or 4 mm (solar protection glass), in each case in conjunction with the building regulations. The percentages include a tolerance of ± 2 percentage points.
Insulating glass may only be transported and stored vertically. Intermediate layers (plastic, cork pads, etc.) should be placed between the panes. When transporting units of different sizes, spacers such as foam, cork, plastic pads or the like are used to prevent the pane edges from causing chafing on the glass surface.
Through such transparent mirrors, one can observe a lighter room from a darker one without being seen. In the lighter room, the two-way mirror looks like a normal, opaque mirror. Reversing the lighting conditions also changes the transparency.
V
The ISOLAR Group assesses the visual quality of insulating glass units in accordance with DIN EN 1279-1:2018-10, Annex F.
See here: ISOLAR Manual Tolerances
W
Walk-on glazing, regulated in the DIN 18008-5, is horizontal glazing, which is used in conventional use exclusively by persons. Max. load 5 kN/m² for vertical payload. Possible applications are e.g. stairs, pedestals, walkways and covers of light wells.
Walk-on glazing, regulated in DIN 18008-6, is horizontal glazing that can be transited in the area of workplaces for the required construction, maintenance and cleaning work. This type of glass must have the property of conditional accessibility and fall-through resistance.
The wettability of the glass surface on the outside of the insulating glass may be different as a result of impressions of rollers, fingers, labels, paper dust, vacuum cups, sealant residues, lubricants or grease or environmental influences. In wet glass surfaces due to condensation, rain or cleaning water, the different wettability can become visible.
Polished wire glass with plane parallel surfaces. The wire mesh insert has a splinter binding effect, but it is not safety glass.
Wired ornamental glass/wire glass is an ornamental glass with wire mesh inlay, whose surface is shaped like a relief on one or both sides. This glass type in “white” or coloured is translucent, but not transparent. The wire insert has a splinter binding effect, but wire ornamental glass is not safety glass.