Making People's Lives More Comfortable while Reducing Environmental Impact

Structure of Ecoglass

Ecoglass (Low-E double-glazing glass)*1 is composed of multiple sheets of glass, between which dry air is sealed to increase the heat insulating performance. Moreover, a special metal coating is applied to the inner face of one glass sheet to suppress heat transfer between the glass sheets. By blocking strong sunshine and outdoor heat in summer and by keeping the heated room warm by preventing cold from being transferred into the room in winter, Ecoglass helps reduce the use of energy for cooling and heating, thereby contributing to CO₂ emissions reduction. Replacing the window glass of a detached house in Tokyo with Ecoglass allows a reduction of CO₂ emissions by 265.5 kg annually and a saving of approximately 50,000 yen in cooling and heating costs.*2 This is equivalent to the amount of CO₂ emissions that can be reduced by planting 25 beech trees.*3

*1 Ecoglass is the trade name for low-emissive double-glazing glass products as defined by the Flat Glass Manufacturers Association of Japan. Ecoglass refers to glass that meets the following requirements: to have heat insulating performance that meets the criteria for type III heat-insulating double glazing glass defined in Japan Industrial Standards (JIS) R3209-1998 on double glazing glass; and to provide heat shielding performance that meets the next-generation energy conservation criteria (1999) for the summer sunshine shielding rate with the use of accessories, such as net curtains, set for region IV (Kanto, etc.) and region V (Miyazaki and Kagoshima Prefectures).

*2 Calculated in reference to the website of the Flat Glass Manufacturers Association of Japan, specifically to the results of simulations by the SMASH to identify the energy conservation effect and CO₂ emissions reduction through the use of heat-insulating Low-E double-glazing glass for house windows (published by the Association in March 2003)

*3 Calculated by dividing the CO₂ emissions reduction amount (265.55 kg) by the amount of CO₂ absorbed by a beach tree per year, in reference to the website of the Flat Glass Manufacturers Association, where the amount of CO₂ absorbed by a beach tree is reported to be 11 kg according to the survey conducted by the Forestry and Forest Products Research Institute.

Mechanism of Ecoglass

In summer

In winter

Window glass for newly built houses <Sun Balance>

Sun Balance is a window glass using Low-E insulating double glazing that is designed for newly built houses and registered as an Ecoglass product and recommended by the Flat Glass Manufacturers Association of Japan*4. It complies with the Next-Generation Energy Conservation Standard established by the Ministry of Economy, Trade and Industry and the Ministry of Land, Infrastructure and Transport to reduce air-conditioning energy consumption by about 20%.
Sun Balance, composed of a 3 mm thick glass pane, a 6 mm thick air layer, and another 3 mm thick glass pane, keeps out 57% of the solar heat, while single sheet of glass can only keep out 11% of the solar heat.
In winter, when you don't want to let heat out of the room, Sun Balance insulates twice as effectively as a single sheet of glass.

Single sheet of glass (3 mm)		<Sun Balance> (3 mm + 6 mm air layer + 3 mm)

Comparison of thermal insulation performance by thermal transmittance*5
(Sun Balance is used)

Single sheet of glass (3 mm)		<Sun Balance> (3 mm + 6 mm air layer + 3 mm)

*4 Flat Glass Manufacturers Association of Japan is a Japanese association of domestic flat glass manufacturers formed by three members: Asahi Glass Co., Ltd.; Nippon Sheet Glass Co., Ltd.; and Central Glass Co., Ltd. It is engaged in developing policies on building glass, research and investigation on safety of buildings and cars, establishment and revision of relevant JIS and ISO standards, participation in establishment or revision of building work standard specifications, preparation of statistic data related to flat glass, and many other activities related to the flat glass industry in general.

*5 Thermal transmittance: Value to indicate thermal movement at a specific portion, such as wall or window. It is the “heating value that moves per square meter when the temperature difference between the outside and the inside is 1°C.” The smaller the value, the higher the thermal insulation (Unit: W/m²•k)

“Window glass can't be changed because you live in an apartment.” “I can still use the present glass. I don't want to waste it.” This is understood, but how about attaching another sheet of glass inside the present window? You can expect CO2 emission reduction benefits equal to those of Sun Balance. This is achieved by the <Inner Window mado mado>. For example, if the window uses single sheet of glass, 48% of the heat generated inside the room is released through the window, but if you install the <Inner Window mado mado>, additional glass using Low-E insulating double glazing to enhance thermal insulation, the effective thermal insulating performance provided by the air layer between the existing glass and the <mado mado> glass will keep the interior heat inside. It provides thermal insulation about three times greater than that of a single sheet of window.
Development of products that indirectly reduce CO2 emission while being used for their intended purpose, which is not to reduce CO2 emissions, has not just recently begun. It started in 1992, and the products have been sold since then. Asahi Glass Flat Glass Company is committed to further improvement of eco-friendliness in its window products as well as to wider diffusion of Sun Balance and <Inner Window mado mado>.

Comparison of Thermal Insulation in Thermal Transmittance
(Subject: <Inner Window mado mado>)

Single sheet of glass (3 mm)		<Inner Window mado mado> Low-E insulating double glazing [External window (5 mm) + 80 mm air layer + <mado mado> Low-E insulating double glazing (3 mm + 6 mm air layer + 3 mm metal film glass)]