Translucent Thermal Insulation
Saving energy is a hot topic worldwide. The thermal insulation of building envelopes is an important part of contemporary architecture. Yet advances in glass transparency of the last three decades must not be pushed back in favour of energy savings architectural achievement. “Transparent insulation” was therefore developed and designed to offer not only unique economic and environmental benefits, but to also guarantee both comfort and convenience.
Technological advances of the last three decades have produced systems and equipment that can coat high-tech insulating glass with razor-thin, neutral coatings using low-cost processes. This has optimized the “e” emissivity capability for thermal insulation as low as 0.01, whereas for normal float glass, e is 0.89.
From an economical perspective, however, this development and its application in new buildings is only the first steps. The next step must be to integrate this new glass technology into the millions of square meters of glazed areas of windows and façades. This is nearly automatic for new buildings today. However, existing buildings represent a much larger opportunity, and there is a lot of advocacy work to be done so that the ecological, economic and climate goals can be achieved.
In times of steadily increasing heating energy costs, this economical benefit presents a persuasive argument. Just making a simple change, such as glazing offers a rather short amortization period and also offers the occupants remarkable improvements in convenience and comfort (see > chapter 5.3). Tthe following formula offers one possibility for estimating the energy savings potential provided when replacing outdated glass with modern thermal insulation:
|U-Wert Ihrer jetzigen Verglasung||U value of your existing glazing|
|U-Wert Ihrer künftigen Verglasung||U value of your future glazing|
|Verglasungsfläche in m2||Glazing area in m2|
|Heizgradtagzahl Nach VDI 4710||Heating degree tag number according to VDI 4710|
|Umrechnung von Kilogramm auf Liter: 1 kg Heizöl = 1.19 Liter||Conversion of kilograms to liters: 1 liter = 1.19 kg fuel oil|
|Heizwert des Brennstoffes: bei leichtem Heizöl etwa 11.800||Heat value of fuel: light fuel oil at approx. 11,800|
|Wirkungsgrad der Heizungsanlage: bei Ölheizung etwa 0.85||Heating system efficiency: oil heater at about 0.85|
Every liter of fuel oil or cubic meter of natural gas that can be saved through using advanced glazing reduces CO2 emissions and provides an ecological benefit. Fossil fuel resources are also saved by reducing their consumption and in addition, glass is one hundred percent recyclable because it is made from natural raw materials. Due to its natural ingredients and superior energy-balancing properties, glass should not be overlooked or dismissed as a viable material in globally recognized certification programs for building sustainable and environmentally friendly buildings.
Leadership in Energy and Environmental Design (LEED) is a leading system in this field. Other systems, for example, are DGNB or Breeam. Buildings following these systems use resources more efficiently than conventional techniques because they take all phases within the life cycle of a building into account – starting with design and construction to renovation, and eventually demolition and proper clean-up.
Apart from its economic and ecological aspects, one important goal of building with glass is the tangible improvement in living and working environments. Tinted float glass installed in insulated glass (- Section 3.2) increases the glazing’s room-side surface temperature, thus drastically minimizing unpleasant drafts in an area where glazing is present.
|Oberflächentemperatur bei 20 °C Raumtemperatur [°C]||Surface temperature at 20 °C room temperature [°C]|
|Außenlufttemperatur [°C] Glasart||Outside air temperature [°C] Type of glass|
|2-fach Isolierglas||2-pane insulated glass|
|2-fach Isolierglas beschichtet||2-pane coated insulating glass|
|3-fach Isolierglas beschichtet||3-pane coated insulating glass|
Modern glass increases this temperature to a near room-temperature level and significantly improves the comfort level of one’s home. The decisive factor in comfort is the temperature difference between ambient air and the adjacent wall and window surfaces. Most people find a room to be particularly comfortable when the temperature differences between wall (glass) and room air is not more than 5 ° C and between foot to head height is not more than 3 ° C.
|Behaglichkeitsdiagramm nach Bedford und Liese||Comfort chart according to Bedford and Liese|
|unbehaglich warm||Uncomfortable, hot|
|unbehaglich kalt||Uncomfortable, cold|
|hochwärmegedämmte Wand||Highly insulated wall|
|iplus neutral E||iplus neutral E|
The diagram above shows the range where ambient air feels most comfortable. Humidity should always be viewed as dependent on room temperature. When the air temperature is cooler, then the humidity should be higher for the space to feel comfortable. When the room temperature is higher, the humidity should be lower.