New Advances In Glazing Materials -- Phase-Changing Heat-Storing Thermal Mass Capability Is Now Reality
Environmental Building News reported on a revolutionary development in glazing materials in its August 2010 edition. The product, GlassX , is a quadruple (or at least double) glazed system developed in Europe that incorporates a phase-changing material that is capable of storing heat. (NOTE: When accessing the GlassX website, it will NOT initially be in English; click on EN at the top of the page.) In North America, GlassX is distributed through Greenlight Glass Systems in Vancouver.
In its full version, the GlassX system is quadruple glazing unit that has three separate insulating glazing units to create an assembly about three inches thick, with a weight of almost 20 pounds (95 KG/square meter)
The outermost section of the system is filled with a low conductive gas such as Krypton that has a prismatic filter suspended into it. This prismatic filter is designed to reject the higher angle light (greater than 40 degrees -- Summer sunlight) but allow lower angle winter sunlight (less than 35 degrees) to pass through. Thus, we now have passive solar heating with an automatic summer control that serves the duty of a window equipped with automated shades or louvers incorporated into a single glazing unit.
Obviously, this form of the system is best suited for south-facing sections of the building, as we can now maximize the winter solar gain, while sharply curtailing the unwanted summer heat gain. This is aided by an inner facing layer of low-emissivity (low-e) coated cavity to retard heat transfer in a similar manner to that of standard double glazed systems.
The real crowning glory in this system is the innermost layer that faces the interior of the building space. This is an additional cavity filled with polycarbonate channels that contain a salt hydrate phase changing material (PCM). This material will change from a solid to liquid over a short range of temperature. This is known as Phase Change. In this application, GlassX will change from solid (crystal) to liquid from 79 degrees F. to 86 degrees. This property allows for the heat storage and release to take place at the room-temperature range. It is the phase change that allows for the storage and release of heat. The ice to water or water to steam is the best example of this. In order to get the phase change, a considerable amount of energy far and beyond that normally needed is required to get the temperature to raise (or lower) that one degree to the phase change. Once this energy has been applied, the phase will change, and with it, substantial energy storage or release is seen. For example, water can continue to absorb a lot energy while at the boiling point (liquid to steam / gas phase) as well as at the freezing point (ice -- solid phase)
The salt-hydrate phase-change material (PCM) according to the article is capable of storing as much heat as nine inches (240 mm) of concrete when an 18 degree F (10 degree C) difference is applied) What really makes this PCM product useful in sustainable building design is the ability of it to release this stored heat gradually over a 20 hour period at a rate of between 16 and 32 BTU per square foot (50-100 Wh / M).
The thermal insulation performance is also impressive, as when krypton gas is used in the outer facing section, the U-value is as low as 0.07. In addition, as long as sunlight is not blocked by the prismatic layer, the light transmission is a high as 45 percent during the liquid phase of the PCM. When the PCM is crystallized, the light transmission will drop to 28 percent.
Perhaps one of the first questions asked would be how can we tolerate only 28 percent light transmission? The answer can be VERY simple: If the budget allows (more on this later) the designer or architect can design the GlassZ system to be a good part of the exterior wall (envelope) of the building. In doing this, the interior wall can either be light transmitting if desired, or light blocking, covered with heat-transmitting material. Regular clear-glazed low-e krypton (or argon) filled windows (often venting) are then placed at appropriate locations for daylight / view / ventilation. The main idea here is to allow GlassX to form the building envelope and at the same time serve as a thermal mass unit.
Durability is the primary concern in any new technology, and with GlassX, this has been addressed by the inventor, Dietrch Schwartz. Dietrch Schwartz guarantees the PCM to last 100 years based on 50 to 100 phase change cycles per year. In addition, there are no moving parts to wear out.
As mentioned at the outset, the full featured GlassX system is best used on a south (or perhaps west) exposure, several other versions (also at lower cost) are available. These include a quadruple system with PCM but no prismatic filter for non-southern exposures, a triple glazed system with prismatic filter and gas filled insulating glass unit IGU and PCM IGU, as well as a dual-glazed unit containg only the PCM.
At the present, the GlassX unit is available in heights up to 110 inches (280 cm) and a maximum width of 59 inches (150 inches) As of last summer, GlassX was only manufactured at two locations -- one in Austria, and the second in Germany. As of mid-2010 there were no installations in North America, but several were in the works.
PCM technology is NOT for every building. It is VERY important to study the ENTIRE building system. Factors to consider are location, orientation and perhaps most importantly COST. GlassX IS RATHER EXPENSIVE at $60 to $90 per square foot ($560 - $970 per square meter) This said, if the the analysis and first cost budget allows, the superior performance may very well justify its use, as it could translate into a rapid payback on investment.
In short, GlassX is an innovation well worthy of consideration by all design teams desiring to produce a sustainable environmentally friendly cost effective building.
In its full version, the GlassX system is quadruple glazing unit that has three separate insulating glazing units to create an assembly about three inches thick, with a weight of almost 20 pounds (95 KG/square meter)
The outermost section of the system is filled with a low conductive gas such as Krypton that has a prismatic filter suspended into it. This prismatic filter is designed to reject the higher angle light (greater than 40 degrees -- Summer sunlight) but allow lower angle winter sunlight (less than 35 degrees) to pass through. Thus, we now have passive solar heating with an automatic summer control that serves the duty of a window equipped with automated shades or louvers incorporated into a single glazing unit.
Obviously, this form of the system is best suited for south-facing sections of the building, as we can now maximize the winter solar gain, while sharply curtailing the unwanted summer heat gain. This is aided by an inner facing layer of low-emissivity (low-e) coated cavity to retard heat transfer in a similar manner to that of standard double glazed systems.
The real crowning glory in this system is the innermost layer that faces the interior of the building space. This is an additional cavity filled with polycarbonate channels that contain a salt hydrate phase changing material (PCM). This material will change from a solid to liquid over a short range of temperature. This is known as Phase Change. In this application, GlassX will change from solid (crystal) to liquid from 79 degrees F. to 86 degrees. This property allows for the heat storage and release to take place at the room-temperature range. It is the phase change that allows for the storage and release of heat. The ice to water or water to steam is the best example of this. In order to get the phase change, a considerable amount of energy far and beyond that normally needed is required to get the temperature to raise (or lower) that one degree to the phase change. Once this energy has been applied, the phase will change, and with it, substantial energy storage or release is seen. For example, water can continue to absorb a lot energy while at the boiling point (liquid to steam / gas phase) as well as at the freezing point (ice -- solid phase)
The salt-hydrate phase-change material (PCM) according to the article is capable of storing as much heat as nine inches (240 mm) of concrete when an 18 degree F (10 degree C) difference is applied) What really makes this PCM product useful in sustainable building design is the ability of it to release this stored heat gradually over a 20 hour period at a rate of between 16 and 32 BTU per square foot (50-100 Wh / M).
The thermal insulation performance is also impressive, as when krypton gas is used in the outer facing section, the U-value is as low as 0.07. In addition, as long as sunlight is not blocked by the prismatic layer, the light transmission is a high as 45 percent during the liquid phase of the PCM. When the PCM is crystallized, the light transmission will drop to 28 percent.
Perhaps one of the first questions asked would be how can we tolerate only 28 percent light transmission? The answer can be VERY simple: If the budget allows (more on this later) the designer or architect can design the GlassZ system to be a good part of the exterior wall (envelope) of the building. In doing this, the interior wall can either be light transmitting if desired, or light blocking, covered with heat-transmitting material. Regular clear-glazed low-e krypton (or argon) filled windows (often venting) are then placed at appropriate locations for daylight / view / ventilation. The main idea here is to allow GlassX to form the building envelope and at the same time serve as a thermal mass unit.
Durability is the primary concern in any new technology, and with GlassX, this has been addressed by the inventor, Dietrch Schwartz. Dietrch Schwartz guarantees the PCM to last 100 years based on 50 to 100 phase change cycles per year. In addition, there are no moving parts to wear out.
As mentioned at the outset, the full featured GlassX system is best used on a south (or perhaps west) exposure, several other versions (also at lower cost) are available. These include a quadruple system with PCM but no prismatic filter for non-southern exposures, a triple glazed system with prismatic filter and gas filled insulating glass unit IGU and PCM IGU, as well as a dual-glazed unit containg only the PCM.
At the present, the GlassX unit is available in heights up to 110 inches (280 cm) and a maximum width of 59 inches (150 inches) As of last summer, GlassX was only manufactured at two locations -- one in Austria, and the second in Germany. As of mid-2010 there were no installations in North America, but several were in the works.
PCM technology is NOT for every building. It is VERY important to study the ENTIRE building system. Factors to consider are location, orientation and perhaps most importantly COST. GlassX IS RATHER EXPENSIVE at $60 to $90 per square foot ($560 - $970 per square meter) This said, if the the analysis and first cost budget allows, the superior performance may very well justify its use, as it could translate into a rapid payback on investment.
In short, GlassX is an innovation well worthy of consideration by all design teams desiring to produce a sustainable environmentally friendly cost effective building.
Posted by Alan L. Englander at 1/21/2011 2:47 PM 
Categories: Direct Solar Gain, Energy Conservation, Building Envelope, Energy Effeciency, Green and Sustainable Design, Glazing, Building Insulation, Building Mass, Daylight, U-Value, Low-E Glazing, Heat Gain, Building Facade, High Performance Buildings, First Cost Savings
Categories: Direct Solar Gain, Energy Conservation, Building Envelope, Energy Effeciency, Green and Sustainable Design, Glazing, Building Insulation, Building Mass, Daylight, U-Value, Low-E Glazing, Heat Gain, Building Facade, High Performance Buildings, First Cost Savings
Comments