Pyrolytic Low E coatings are generally non-reflective and highly transparent coatings applied to clear glass, and are designed to increase the thermal performance of windows. Glass with a low emissivity (Low E) coating is specifically designed to reduce heat transfer and energy costs and works most efficiently in Insulated Glass Units.
The Low E coating is designed to reflect long wave radiation from the glass itself and from the inside or outside. These coatings must be glazed inside the building on surface 2 to ensure the Low E coating functions. They are ideal for use in Insulating Glass Units as they provide very high insulation. The most common being Pilkington Energy Advantage and AFG Comfort E2. Some new Low E coatings are designed with a tint or colour to help control solar gain. These are called Solar Low E Coatings. An example is Pilkington Solar E.
Low E glass was designed for, and performs best,
in Insulating Glass Units and is not generally recommended for single
glazing. It can be handled and cut like float glass and processed
into laminated, heat strengthened, toughened, Insulating Glass Units
and curved glass.
Manufactured in 3, 4, 5 and 6mm
Available in 4, 5 and 6mm
Energy Advantage Low E
& Comfort E2
High performance pyrolytic Low E glass with unparalleled heat control and the appearance of uncoated glass. The glass lets most of the sun’s heat in, while letting a minimum of heat back out. The glass is neutral in colour and has a durable coating that will not oxidise or change colour or performance over time. It has improved UV elimination and heat gain performance compared to clear float, with slightly more light reflectance and less light transmission.
Solar Low E (Solar E)
A special light grey, Low E coating applied to
clear glass. Light transmission is reduced but the shading coefficient
is also reduced providing improved solar control performance over
clear Low E glass. This product is laminated to produce Comfort Plus.
It can be handled and cut like float glass and processed into laminated,
heat strengthened, toughened, and Insulating Glass Units.
Manufactured in 3-6mm
Available in 6mm
2.5 Sputtered Coated Reflective
A high technology process in which metal particles are deposited on the glass surface in a vacuum chamber. Almost any non magnetic alloy can be sputtered, the more common being stainless steel, silver and titanium. Performance characteristics and colour depend on the alloy and coating density, but in general they have better solar control performance than pyrolytic coated glass.
They are often called soft coats as the coating is more susceptible to damage than pyrolytic reflective glass when single glazed. Special care is required in cutting, handling, glazing and cleaning. They are also known as vacuum coated off-line coatings. These coatings are applied to monolithic sheets of glass up to a normal maximum size of 3660 x 2440mm, which can be cut to size as normal glass.
These products are often heat treated due to the risk of thermal stress breakage. When this is required the product must be toughened or heat strengthened first to pre-determined sizes, and then sputtered coated before it is imported. This increases lead times and adds cost when compared to pyrolytic products. Sputtered coated reflective glass is normally imported into New Zealand for special contracts, in either annealed, laminated, toughened, heat strengthened or IGU form. The laminated option is ideal as the coating is inside the laminate, protecting it from damage. With exceptions, sputtered coated products have better shading coefficient values than pyrolytic products.
The coating codes are normally based on two letters and two numbers eg TS21. The letters identify the type of coating and the numbers indicate the visible light transmission on 6mm clear glass. The higher the number the higher the visible light transmission, conversely the lower the number the better the glass performs in reducing solar gain.
Example: TS 21 = Titanium silver coating with 21% VLT
These coatings can be applied to tinted float, eg TS 21 on Green, but the light transmission will be reduced by the green tinted glass to 18%. Common trade names are Suncool and Solarplus.
2.6 Sputtered Coated Low E
Sputtered coated Low E glasses have transparent layers of silver and metal oxides sputtered onto the glass surface. The metal oxides, which surround the silver, protect and suppress the visible reflectance of the silver. These are high performance Low E coatings and can only be used in an Insulating Glass Unit. Normally these coatings are neutral in colour but some can be tinted to provide extra solar control performance. Examples are Solarplus LE54 and LE80, Planibel G, Top N, and Energy N. Most of these products must be coated after heat treatment but the Planibel range has a version that can be toughened after coating. All products, except the aforementioned Planibel range, are only available as a special import and are not stocked in New Zealand.