Final Report Summary - MEM4WIN (Ultra thin glass membranes for advanced, adjustable and affordable quadruple glazing windows for zero-energy buildings)
Executive Summary:
Buildings are responsible for 40% of energy consumption and 36% of EU CO2 emissions. According to the Energy Efficiency Plan of the European Commission, the largest cost-effective energy saving potential lies in buildings. Directive 2010/31/EU on the Energy Performance of Buildings (EPBD) foresees that Member States should draw up national plans for increasing the number of nearly zero-energy buildings and the Commissions’ Lead Market Initiative “Sustainable Construction” aims at the development and growth of the sustainable construction market.
Windows are critical elements to control the energy performance of buildings especially for zero-energy buildings. It is of paramount importance to develop windows which show reduced U-value, weight and costs and certain features to control and harvest energy. Such a window will have a high impact in the window industry and will reduce greenhouse gas emissions as long as the window is affordable, can be used for residential and office buildings in every climate zone, for new constructions or in retrofitting of older buildings.
Therefore
(1) MEM4WIN developed a novel IG-Unit for quadruple glazing containing ultra thin glass membranes dedicated as frameless openable windows for direct application in facades. Due to this approach U-values of 0.3 W/m²K were achieved reducing weight by more than 50% and costs by 20%.
(2) MEM4WIN developed ink-jet printed organic photovoltaics (OPVs) and fully integrated solar thermal collectors for energy harvesting and micro mirrors for energy control and advances day lighting.
(3) Fabrication costs were further reduced by replacing conventional and cost intensive materials used for contacts like ITO and silver by graphene. MEM4WIN developed production methods like transfer printing and ink-jet printing to fabricate contacts for OPVs.
The developed technologies were integrated in several demonstrators. From 21st to 24th of October, 2014, MEM4WIN presented the preliminary MEM4WIN façade system and first prototyps of OPV-glass-glass modules and of micro mirror arrays at the „glasstec“, the world's largest trade fair for the glass industry and its suppliers, in Düsseldorf, Germany.
The final presentation of the modified MEM4WIN façade mock-up took place at "Frontale", a leading trade show for windows, doors and facades held in Nuremberg from 16th to 19th of March, 2016. MEM4WIN presented the modified façade mock-up at the exhibition booth of LiSEC and a quadruple IG-unit in a double wing terrace door with polymer frame at the VEKA exhibition booth respectively.
Following single exploitable results of the MEM4WIN project are described in the publishable summary in detail:
• Tempered ultra-thin glass membranes
• Frameless, openable window for application in facades
• Novel lamination techniques for fabrication of OPV glass-glass modules
• Quadruple insulated glass unit with novel spacer technology
• Solar-thermal collector (fully integrated in IG-unit)
• Doped CVD Graphene for direct transferred transparent contacts
• LPE graphene ink for printing on organic solar cells
• Micromirror Arrays for Smart Windows
• OPV ink for direct printed organic photovoltaic cells
Project Context and Objectives:
Introduction
In the future, windows will even supply energy and take on other intelligent functions that are crucial for the comfort of the building users: shading, light control, lighting, noise reduction.
The ‘window of the future’, which includes all of the above functions, was the scope of the MEM4WIN project (https://web.archive.org/web/20190508103103/http://www.mem4win.eu/).
The Austrian industrial company LiSEC – global leader in glass processing machines and a pioneer in the production of insulating glass – was coordinating the international research project. The project, which began on 1 October 2012 and had a run time of 42 months (project close: March 2016), was funded by the European Commission within the Seventh Framework Programme (project number: NMP3-SL-2012-314578). The following partners were involved in the project, in alphabetical order:
1.▪ Aixtron SE and Aixtron Ltd.
2.▪ Belectric OPV GmbH
3.▪ Consiglio Nazionale delle Ricerche / IMIP
4.▪ Durst Phototechnik AG
5.▪ Energy Glas GmbH
6.▪ Johannes Kepler University of Linz / ZONA
7.▪ Korea University / NMDL
8.▪ LiSEC Austria GmbH
9.▪ PROFACTOR GmbH
10.▪ Tiger Coatings GmbH and Co. KG
11.▪ The Chancellor, Masters and Scholars of the University of Cambridge / DENG / NMS
12.▪ University of Kassel / INA and CESR
Background
Buildings are responsible for 40% of energy consumption and 36% of EU CO2 emissions. According to the Energy Efficiency Plan of the European Commission, the largest cost-effective energy saving potential lies in buildings. Directive 2010/31/EU on the Energy Performance of Buildings (EPBD) foresees that Member States should draw up national plans for increasing the number of nearly zero-energy buildings and the Commissions’ Lead Market Initiative “Sustainable Construction” aims at the development and growth of the sustainable construction market.
Windows are critical elements to control the energy performance of buildings especially for zero-energy buildings. It is of paramount importance to develop windows which show reduced U-value, weight and costs and certain features to control and harvest energy. Such a window will have a high impact in the window industry and will reduce greenhouse gas emissions as long as the window is affordable, can be used for residential and office buildings in every climate zone, for new constructions or in retrofitting of older buildings.
Objectives
Therefore, MEM4WIN developed
(1) a novel IG-unit for quadruple glazing containing ultra thin glass membranes dedicated as frameless openable windows for direct application in façades. Due to this approach U-values of 0.3 W/m²K were achieved reducing weight by more than 50% and costs by 20%.
(2) ink-jet printed organic photovoltaics (OPVs) and fully integrated solar thermal collectors for energy harvesting and micro mirrors for energy control and advances day lighting.
(3) production methods like transfer printing and ink-jet printing to fabricate contacts for OPVs. So, fabrication costs were further reduced by replacing conventional and cost intensive materials used for contacts like ITO and silver by graphene.
Results
(1) LISEC introduced a novel IG-unit for quadruple glazing containing ultra thin glass membranes dedicated as frameless openable windows for direct application in façades. U-values of 0.3 W/m²K were achieved. The feasibility of tempering and integration of 0.9mm ultra thin glass membranes was demonstrated. However, the change in glass thickness in the final demonstrator from 0.9mm to 1.6mm for inner and middle panes is due to current availability of low-e coated glass. In near future availability of 1.3 mm glass will be given and can be considered. As outer laminate 2+2 mm tempered thin glass laminate was chosen in order to achieve given windload requirements.
Due to the use of tempered glass membranes (<0.9 mm) in a new frameless window design weight is reduced (50%). The new frameless window allows to be integrated in a façade without any visibility of the wing. Low distortions in the appearance of the façade was achieved due to asymmetric construction of the IG-unit.
(2) Several printed OPV modules were produced by BELECTIC OPV GmbH and integrated directly in a diffusion-tight glass-glass-encapsulation with edge sealing by LiSEC and therefore the modules are perfectly protected against environmental influences. A semiconductor ink with optimized jetting behavior was formulated by PROFACTOR (lab scale) and Tiger Coatings (upscaling) and OPV modules were inkjet printed with a total active area of 125 cm². In the next step OPV modules will be printed with an industrial inkjet printer, which combines perfect design-freedom with the ability to print very large areas. The industrial inkjet printer was developed by Durst. Apart from the MEM4WIN-project, OPV modules from BELECTRIC OPV were already used for the German pavilion at the World Expo 2015 in Milano, where stylised trees integrated with the OPV modules, which are embedded in a flexible film, provide shade for visitors and generate energy at the same time.
Miniaturizing lamella blinds down to micromirrors has some very obvious advantages: Beneath segmentability and the “uncut” outlook, they are protected between the window panes against wind, weather and dirt. But the miniaturization is beneficial as well to considerably improve the mechanical stability of such devices developed by University Kassel. The electric field between the mirrors and the electrode upon the pane will make the mirror switch. This makes those mirrors maintenance free for their whole lifetime.
(3) Concerning graphene research, the investigation and optimisation works have led to a reliable CVD process for the preparation of defect free graphene. Four layers of graphene were grown and doped by CNR on glass and showed a resistivity around 25 Ohm/sq and a transmittivity above 90%. Within the project, a new CVD tool was developed by AIXTRON. This new equipment is capable of producing 400cm2/h of monolayer graphene. The concept for this new system is fully scalable and could be used to produce very large area graphene > 1x1m.
First integration in OPV cell of graphene transferred on glass was realized. This attempt showed that with CVD graphene it is possible to make functional solar cells and that the optical density is good.
Furthermore, graphite was successfully exfoliated in water and additionally concentrated to produce a graphene ink with 1 mg/ml. Since for inkjet printing the graphene flakes have to be smaller than 1 µm and the ink has to fulfil certain other jetting and printing requirements, the ink was further optimized for inkjet printing concerning viscosity and boiling point with additives. This was then incorporated into inverted solar cells with an active area of 27 mm² by inkjet printing on glass/ITO/ZnO/P3HT:PCBM substrates in ambient atmosphere. Silver is used as top electrode. The cells showed efficiencies of up to 1.8 %.
The developed technologies were integrated in several demonstrators. From 21st to 24th of October, 2014, MEM4WIN presented the preliminary MEM4WIN façade system and first prototypes of OPV-glass-glass modules and of micro mirror arrays at the „glasstec“, the world's largest trade fair for the glass industry and its suppliers, in Düsseldorf, Germany.
The final presentation of the modified MEM4WIN façade mock-up took place at "Frontale", a leading trade show for windows, doors and facades held in Nuremberg from 16th to 19th of March, 2016. MEM4WIN presented the modified façade mock-up at the exhibition booth of LiSEC and a quadruple IG-unit in a double wing terrace door with polymer frame at the VEKA exhibition booth respectively.
A detailed description of following single exploitable results of the MEM4WIN project can be found at the MEM4WIN project website https://web.archive.org/web/20190508103103/http://www.mem4win.eu/ as well as in the publishable summary:
• Tempered ultra-thin glass membranes
• Frameless, openable window for application in facades
• Novel lamination techniques for fabrication of OPV glass-glass modules
• Quadruple insulated glass unit with novel spacer technology
• Solar-thermal collector (fully integrated in IG-unit)
• Doped CVD Graphene for direct transferred transparent contacts
• LPE graphene ink for printing on organic solar cells
• Micromirror Arrays for Smart Windows
• OPV ink for direct printed organic photovoltaic cells
Project Results:
1 Tempered ultra-thin glass membranes
1.1 The idea behind
The weight of a window could be reduced by 50 per cent through the use of tempered ultra-thin glass membranes as middle or inner pane within a triple or quadruple IG-unit (down to ~0.9mm). But todays tempered glass applications like solar modules or other weight and transmission sensitive applications are based on thinnest commercial available glass – 3.0 mm.
The reason is simply the physical limit on conventional tempering furnaces based on ceramic rollers as transport system; these rollers are arranged in a certain minimum distance but still glass with a temperature close to Tg (at 650 °C) tends to deformation when passing the free space between the rollers, thus creating so-called roller waves in tempered glass, being visible as uneven deflection known from reflecting facade.
A new approach of air cushion transportation within tempering furnaces enables tempering of thin glasses without any roller waves, proven today already in glass thicknesses down to 1.8 mm. These thin glasses are used preferably in new solar module applications, enabling weight reduction as well as higher transmission. This technology is patent pending by LiSEC and a few installations within Europe and Asia are already existent.
Tempered thin glass opens up new unparalleled possibilities. Lightweight, flexible and durable glass units without optical distortions and lower stress for the spacer system are ideally suited for use in modern architecture with highly energy-efficient windows/facades. Using tempered thin glass allows for considerably lighter modules with remarkably better thermal insulation values and increased lifespan.
1.2 Advantages
Due to the air cushion technology these developments allow to save energy for the tempering of up to 40%. The LiSEC air cushion system is ideal for surface-treated or double-sided coated glass sheets. The required energy is controlled by the air volume and can be immediately adjusted to a wide range of glass properties. (e.g. ultra clear, Low-E, Suncoat, enamel, etc.). No contact is made, which means there is no wear. Ceramic is a highly wear-resistant material. It distinguishes from conventional roller furnaces by
• The glass surface is not touched
• Air cushions are used instead of ceramic rollers
• Maximum convection in the circulation system
• Symmetrical energy input
The utilization of ultra-thin tempered glass membranes within highly energy efficient windows shows following advantages:
• Lower breakage losses due to thin glass sheets of enormous strength and flexibility
• Lower distortions in façade in the event of alternating climate loads due to adjustment of the inner panes to gas volume changes (while the outer pane remains in plane, because the outer pane is thicker in order to be able to carry the wind loads)
• Lower stress on spacer bars while climatic loads due to flexible tempered thin glass adjustment to gas volume
• Lower loads on fittings and frames due to weight reduction
• Improved working conditions for window construction employees
• Higher transmission (+1% for each mm glass thickness saved) (less absorption through thinner glass)
1.3 Results
With a new air cushion tempering furnace LiSEC demonstrated in experiments that the glass thickness could be reduced down to ~ 0.9 mm. The membrane effect of the flexible tempered thin glass sheet in the unit considerably reduces optical distortions of the thicker exterior glass (thickness regarding wind loads). Even with large temperature changes, the structure compensates for pressure fluctuations occurring in the unit.
2 Frameless, openable window for application in facades
2.1 The idea behind
A new frameless window design allows reducing considerably the weight of windows as well the visibility of frames in facades. Specially, architects are increasingly giving priority to uniform “reflection” in facades as well as to no visual difference between the glass facades and openable window wings.
Therefore window elements within full glass façade were chosen; only for this application a certain element needs to have this capability, where architectural aspects of uniform “reflection” are preferred and have to be considered.
So a parallel outbound opening was chosen to be useful, incl. motorized drive in order to avoid implementation of manual opening elements.
2.2 Advantages
The output of MEM4WIN will be an advanced, adjustable and affordable quadruple glazing window for zero-energy buildings. Due to the use of ultra-thin glass membranes (<0.9 mm) in a new frameless window design weight is reduced (50%). The new frameless window allows to be integrated in a façade without any visibility of the wing.
2.3 Results
The openable wing is not visible in the façade and there are low distortions in the appearance of the façade due to asymmetric construction of the IG-unit. This was shown with the presented exhibit at the Glasstec 2014 showed.
3 Novel lamination techniques for fabrication of OPV glass-glass modules
3.1 The idea behind
Traditional PV technologies are well established in roof top or solar park applications but are not appropriate for integration into facades, shading elements or windows. Lifetimes of more than three years have been demonstrated for flexible modules. Accelerated lifetime tests predict lifetimes of more than fifteen years for glass encapsulated modules. With the new sealing technique which will be developed by LIS during the project we expect to achieve a durability of solar cells up to 30 years since the OPV will be encapsulated 700 times tighter than ever achieved so far.
3.2 Advantages
Integration of solar modules into insulating windows will lead to a mutual benefit: on one hand, the windows will be provided with functionality. On the other hand, OPV modules will be isolated from water and oxygen for up to 30years, which will greatly enhance their stability. The Lisec lamination technology with additional diffusion-tight edge sealing and the Krystalflex encapsulation foil protects OLED very well against environmental conditions.
3.3 Results
The several printed OPV modules produced by Belectric OPV GmbH are directly integrated in a diffusion-tight glass-glass-encapsulation with edge sealing and therefore the modules are perfectly protected against environmental influences. It was produced in a newly developed vacuum lamination process by LiSEC for glass-glass-laminates with edge sealing. Accelerated lifetime tests predict a lifetime of 30 years since the modules have been encapsulated with a water vapour diffusion tightness of 0.01 g/m²day. This value is 700 times better compared with lamination foils of conventional open module edge glass-glass modules.
The novel vacuum lamination technology has been designed especially for PV module encapsulation and is characterised by gentle pressing and extremely short cycle times. Pre-lamination with this vacuum lamination process takes just about 3 to 5 minutes. Since curing is performed in a separate cycle, the laminator no longer is the bottleneck in PV module production.
4 Quadruple insulated glass unit with novel spacer technology
4.1 The idea behind
New legislative regulation for further improvements are in progress creating demand for further improved Ug-values, thus new design and manufacturing processes, materials and technologies are required. Since a simple step toward quadruple IG units is not feasible, these new challenges must be overcome like
- increase of weight due to 4 glass layers
- higher heat transition by higher amount of edge materials/sealant
- mechanical instability of edge connection between 4 glass layers
- lower light transmission with each additional glass sheet
4.2 Advantages
MEM4WIN will introduce a novel IG-Unit for quadruple glazing containing ultra thin glass membranes dedicated as frameless openable windows for direct application in facades. Due to this approach U-values of 0.3 W/m²K can be achieved reducing weight by more than 50% and costs by 20%.
The new quadruple insulated glass unit with novel spacer technology reduces weight and costs and lowers the U-value further (down to 0.3 W/m²K)
4.3 Results
The change in glass thickness from 1 mm to 1.8 mm for inner and middle panes is due to current availability of low-e coated glass. In near future availability of 1.3 mm glass will be given and can be considered. As outer laminate 2+2 mm glass laminate was chosen or also thicker glasses depends on the local situation to achieve required windload requirements. New calculations of the U-value show that the spacer filled with Argon gas can be reduced from 22 to 20mm, which helps to fulfill the requirements of profile manufacturers for less broad profiles.
5 Solar-thermal collector (fully integrated in IG-unit)
5.1 The Idea Behind
The idea is to give the insulation not only the function of saving energy, but also to produce energy!
In Europe about 50% of the energy for the heating of buildings to be expended, therefore we want to reduce this demand in the form of solar thermal energy. Solar thermal collectors for energy harvesting are fully integrated in the IG-Unit.
The application in gas-tight insulation provides an ideal prerequisite for this type of collector.
The structures are not thicker than insulating, therefore allows the collector into existing mullion / transom constructions install.
5.2 Advantages
• Low panel thickness compared to conventionally flat plate collectors
• Energy losses reduced by insulating properties (gas-tight and low-e coating)
• Built in the facade 90 degrees with good optical appearance
• Improved energy efficiency in the transitional months
5.3 Results
Energy Glas has produced a gas-tight quadruple insulating glass collector with Lisec technology. The collector works and with improved performance data as a normal flat plate collector. It has better energy harvest in the transitional months and a very good optical properties of the collector for the façade. The insulating collector is gastight and flexible dimensions and special shapes are possible.
6 Doped CVD Graphene for direct transferred transparent contacts
6.1 The idea behind
The objective is to replace indium tin oxide (ITO), which is the common material used as transparent conductive layer in electrical device, by graphene synthesised via chemical vapor deposition (CVD) and the use of a roll to plate process for the transfer. Graphene has a higher transparency than ITO and is a promising candidate for cost reduction, and for overcoming the shortage of indium supplying. Especially the roll to plate process that will be developed within the project is an easy and fast process to transfer CVD graphene from copper foils onto glass and will make it possible to handle graphene layers for mass production. The specific goal within MEM4WIN will be to fabricate large area CVD graphene, transfer it to glass and use it for OPVs, Micro Mirrors and OLEDs.
6.2 Advantages
Graphene layers should be capable of meeting the required minimum conductivities of 10-5 S.cm-1 (for charge extraction layers) and area conductivities of 0.05 S.cm-1 (for electrodes) while still providing transparencies of more than 80% over the whole visible and near infrared region.
6.3 Results
Within the framework of the MEM4WIN project we successfully achieved the transfer on glass plate of CVD graphene grown on copper. The investigation and optimisation works have led to a reliable CVD process for the preparation of defect free graphene. The developed transfer process has enabled the preparation of graphene on glass at lab scale. Four layers of graphene were grown and doped by CNR on glass and showed a resistivity around 25 Ohm/sq and a transmittivity above 90%.
To enable large scale applications for graphene, all tools used for material growth and transfer needs to be scaled up. Within the project, a new CVD tool was developed. This new tool allows a significant throughput increase for the production of high quality monolayer graphene. This new equipment is capable of producing 400cm2/h of monolayer graphene. The concept for this new system is fully scalable and could be used to produce very large area graphene > 1x1m.
First integration in OPV cell of graphene transferred on glass was realized. This attempt showed that with CVD Graphene it is possible to make functional solar cells and that the optical density is good. The OPV cell tested consisted of a layer stack of ZnO, P3HT:PCBM, and HIL were coated and a 300 nm Ag electrode was evaporated. The first trial gave 40%FF and 0.8% efficiency, which is very promising. With the optimized transfer process and with graphene doping, a stable sheet resistance of 35 Ohm/sq at a transparency of 90,2% were obtained with a 4-layer-graphene sample (5x5cm).
7 LPE graphene ink for printing on organic solar cells
7.1 The idea behind
Graphene can be produced by methods like growth on metal substrates by Chemical Vapor Deposition (CVD) or annealing SiC substrates [1]. However, for industrial applications also Liquid Phase Exfoliation (LPE) is a prominent way for a high-yield production of graphene flakes [2] (Figure 1). In this process a dispersion of graphene in a solvent is obtained that can be used as ink for inkjet printing (Figure 2). The top electrode in organic photovoltaic (OPV) solar cells is usually silver deposited by thermal evaporation [3]. Our goal was to replace the silver grid by an inkjet printed graphene pattern.
A common solvent for LPE of graphite is N-methyl-pyrrolidone (NMP) [4]. However, it is forbidden to use with most of the print-heads, obviously, due to its high dissolution power. Moreover the reproduction toxicity of NMP can reduce the working place safety.Several suitable solvents for printing were investigated [5]; however, no organic solvent based graphene ink could combine all requirements: stability, compatibility with the substrate and high conductivity. Therefore it was decided to focus on the printing of graphene as hole-transport-layer (HTL). The HTL is the underlaying layer underneath the top electrode (Figure 3) and enables the transport of holes towards the top electrode and blocks electrons due to the favorable energy level.
7.2 Advantages
PEDOT:PSS, a transparent, conductive polymer, is widely used as HTL. However, due to its sensitivity to moisture and oxygen its use leads to limited life times even for encapsulated cells [6]. To improve stability we replace the PEDOT:PSS by inkjet printed graphene. Water can be now chosen as solvent since it is compatible with the underlying active polymer in bulk-heterojunction solar cells. Furthermore, water is compatible with print heads, low-cost and ecologically harmless.
7.3 Results
Graphite is successfully exfoliated in water and additionally concentrated to produce a graphene ink with 1 mg/ml. For inkjet printing the graphene flakes have to be smaller than 1 µm and the ink is further optimized for inkjet printing concerning viscosity and boiling point with additives. This is then incorporated into inverted solar cells with an active area of 27 mm² by inkjet printing on Glass/ITO/ZnO/P3HT:PCBM substrates in ambient atmosphere. Silver is used as top electrode. The cells showed efficiencies of up to 1.8 %.
Up-scaling processes and optimization of the ink are currently under investigation.
7.4 References
[1] F. Bonaccorso, A. Lombardo, T. Hasan, Z. Sun, L. Colombo, A.C. Ferrari, Materials Today, 15 (2012) 564-589.
[2] Y. Hernandez, V. Nicolosi, M. Lotya, F.M. Blighe, Z. Sun, S. De, I.T. McGovern, B. Holland, M. Byrne, Y. Gun’ko, J. Boland, P. Niraj, G. Duesberg, S. Krishnamurti, R. Goodhue, J. Hutchinson, V. Scardaci, A.C. Ferrari, J.N. Coleman, Nature Nanotechnology, 3 (2008) 563-568.
[3] B. Ma, C.H. Woo, Y. Miyamoto, J.M.J. Fréchet, Chem. Mater., 21 (2009) 1413-1417.
[4] F. Torrisi, T. Hasan, W. Wu, Z. Sun, A. Lombardo, T.S. Kulmala, G.-W. Hsieh, S. Jung, F. Bonaccorso, P.J. Paul, D. Chu, A.C. Ferrari, ACS Nano, 6 (2012) 2992-3006.
[5] J. Kastner, I. Gnatiuk, B. Unterauer, I. Bergmair, O. Lorret, G. Hesser, K. Hingerl, D. Holzinger, M. Mühlberger, Imaginano Conference (2013), Bilbao, Spain.
[6] K. Norrman et al. J. Am. Chem. Soc. 132, 16883 (2010)
8 Micromirror Arrays for Smart Windows
8.1 The idea behind
Daylighting in general should be preferred above electric lighting. It is free and characterized as a high illuminance with full-spectrum light which gives a perfect color rendering, variable angles of the light incidence, as well as a big variation in intensity and colors, which gives a positive effect on human well-being. Daylight can also offer a favorable thermal energy inside the buildings. However, daylight can also produce uncomfortable solar glare and very high luminance reflections e.g. on display screens, both of which interfere with good vision.
This problem can be met by a flexible system, which can fit the requirements of daylight illumination, glare protection and heat regulation all at the same time. In order to overcome these problems, millions of micromirrors can be implemented in the interspace of conventional insulation glasses, providing efficient transmission control and significantly improved daylight distribution. Such micromirrors have a size of less than 0,1mm², which means about 12 mirror elements / mm² or 12.000.000 mirrors / m².
8.2 Advantages
Miniaturizing lamella blinds down to micromirrors has some very obvious advantages: Beneath segmentability and the “uncut” outlook, they are protected between the window panes against wind, weather and dirt. Furthermore the miniaturization is beneficial as well to considerably improve the mechanical stability of such devices. The electric field between the mirrors and the electrode upon the pane will make the mirror switch. This makes those mirrors maintenance free for their whole lifetime.
8.3 Results
In principle, the fabrication of micromirrors can be summarized in three steps: deposition of thin-film layers, micropatterning to define the mirror shape and release of the mirror using a self assembling step, in which the mirrors will stand up in a nearly 90⁰ out-of plane position making use of the intrinsic stress of the deposited layers. Within MEM4WIN project, at University of Kassel micromirror arrays of the size of 10 by 10 cm² have been fabricated showing <1 mW/m² power consumption in holding position and at least 75% and 2% transmission (open and closed).
9 OPV ink for direct printed organic photovoltaic cells
9.1 The idea behind
Traditional PV technologies are well established in roof top or solar park applications but are not appropriate for integration into facades, shading elements or windows. Solutions based on thin film technologies exist but are merely "building attached" rather than fully integrated into the building components and are thus not competitive, due to high costs and insufficient flexibility. Moreover, the traditional thin film systems do generally not meet the legal requirements for façade integrated systems. Most important, they do not offer any degrees of freedom in terms of design, as they are not easy to be tailored with respect to colour or transparency.
Organic photovoltaics are a promising alternative to traditional PV technologies, as they meet all of the requirements described above.
9.2 Advantages
Organic Photovoltaic Modules are due to their outstanding properties, such as
- semi-transparency
- light weighted
- availability of different colours
- design-freedom,
extremely suitable for the integration in glass and thus for the BIPV (Building Integrated Photovoltaics).
9.3 Results
Several printed OPV modules were produced by BELECTRIC OPV GmbH and integrated directly in a diffusion-tight glass-glass-encapsulation with edge sealing and therefore the modules are perfectly protected against environmental influences. An optimized semiconductor ink was developed by PROFACTOR (lab scale) and Tiger Coatings (upscaling) and OPV modules were inkjet printed with a total active area of 125 cm². In the next step OPV modules will be printed with an industrial inkjet printer, which combines perfect design-freedom with the ability to print very large areas. The industrial inkjet printer was developed by Durst . Apart from the MEM4WIN-Project, OPV Modules from BELECTRIC OPV were already used for the German pavilion at the World Expo 2015 in Milano, where stylised trees integrated with the OPV modules, which are embedded in a flexible film, provide shade for visitors and generate energy at the same time. A second shading system was installed in Addis Ababa for the Peace and Security Building of the African Union in the shape of the African continent.
Potential Impact:
The main potential impact of the MEM4WIN project is to replace double and triple IG-units with quadruple IG-units for increasing the energy efficiency of buildings.
Beside the novel quadruple IG-unit within MEM4WIN also other technologies were developed. All in all a number of 30 technology prototypes were realized to demonstrate the reached performance of the single technologies. The description of performance with could be reached with these demonstrators are included in the respective WP-descriptions in the periodic report (m42) as well in deliverable report D8.2.
For instance, we were able to reach the estimated U-value of 0.3 W/m²K and the weight reduction of 50% to 26,5 kg/m². For the cost reduction we had estimated values for the starting value with 117,55 €/m² and for the goal with 93 €/m². As the final cost comparison shows, we reached the estimated reduction of 20% to a standard state of the art window with 175 €/m².
We were able to get the technical performance to replace a CVD Graphene with an ITO, but we were not able to get it done at the estimated costs. The technical potential is now not exhausted. For the graphene ink, we were able to achieve the estimated price, but we were not able to get the performance we need to replace the silver ink. The electrical performance was only reachable when the ink was black, but it should be trans-parent.
As the final Life Cycle Assessment (LCA) shows, we were able to reach a heating demand of 12 kWh/m²a. The cooling energy demand is equal to rooms, equipped with 3-IG windows. Therefore, the estimated value of 30 kWh/m²a can be assumed as reached. The energy demand for lighting is equal to rooms, equipped with 3-IG windows (equal g-value, TL-value). As well the energy demand for office equipment is equal to rooms, equipped with 3-IG windows, because the value is not affected by windows. Therefore, the estimat-ed value of 20 kWh/m²a can be assumed as reached.
To Reduce Embodied Energy we got thinner glass in use. Therefore we were able lower the value from a 4mm float glass of 9,85 kg CO2-eq/m² to 6,74 kg CO2-eq/m² of a thermally treated 1,8mm glass. In a sec-ond step we were able lowering it down to 5,44 kg CO2-eq/m² with the use of a thermally treated 0,9mm glass, see D2.4. In the end, we were able to reduce the GWP between 32% (1,8mm) and 45% (0,9mm).
Dissemination activities within the MEM4WIN project covered activities that informed interested parties about the MEM4WIN project in general, the scientific results and the products/processes developed within the project. The interested parties get informed about the project via the project website and the project presentation (ppt-slides). The scientific results get disseminated via conference contributions (77 contribut-ed talks) and via scientific journals (32 peer reviewed publications) mainly. The developed prod-ucts/processes were presented at fairs and trade shows like at glasstec 2014 and Frontale 2016.
Furthermore, due to presentations of the novel quadruple IG-unit using world's leading communication chan-nels for the glass and window e.g.
• Glass technology Live at glasstec 2014 incl. proceedings
• GDP 2015 incl. proceedings
• CTC 2015 in Pecking
• Interviews in the magazine Glasswelt 12/2015 with UKA (Ulrich Neumann) and ENG (Mirco Franke and Elmar Dohmann)-the professionals in the glass and windows industry get informed about the fact that novel tempered thin glass makes quadruple IG-units with high durability possible. Glass technology journals like ‘Glaswelt’ re-ported frequently. As the comments and articles in the journals show, MEM4WIN initiated a lively debate about advantages and disadvantages of quadruple IG-units. A selection of those articles can be found in the download section of the MEM4WIN website: https://web.archive.org/web/20190508103103/http://www.mem4win.eu/
Exploitation activities covered for instance the presentation of results at fairs like the preliminary façade mock-up and technology prototypes at the glasstec 2014. The updated façade mock up was presented at the Frontale 2016 with quadruple IG-units (Ug-value = 0.3 W/m²K), frameless open-able window, solar-thermal collector, OPV and OLED modules integrated with the novel lamination technology.
The technologies, which were presented, are ready for marketing. Technologies, which have been developed during MEM4WIN project but are not ready for marketing yet like Micromirrors, CVD-Graphene, LPE Gra-phene, inkjet printed OPV, ... have not been included in order to avoid the trap of raising excessive cus-tomer expectations at the commercial fair.
Already during glasstec 2014 we received a great feedback from architects, façade planer, glass Industry, IG-unit producer, profile producer, window producer and façade manufacturer. Most of them see that MEM4WIN was able to solve the right problems, which will help them to get new products into the market. An IG-unit with U-value of 0.6 W/m²K is getting to the standard. At the same time, the market is waiting for the next generation. Will it be the vacuum glazing or could it be only one sheet extra? At the glasstec 2014 the experts were able to get an impression about the advantage of thin glass in an IG-unit. The old mindset of the market to use only thick float glass for the IG-unit was starting to change.
A big factor for driving this issue is the weight reduction, which helps everybody in the value chain. Right now it will be most important for the plastic profile manufacturer because with the existing constructions the reached the weight limits already. Visitors saw also a potential for the thermally treated thin glass in the use of cold bended glass, fire safety glass, OLED glass-glass modules for handrails and so on.
Furthermore, the quadruple IG-unit provoked reaction in the media like journals Glaswelt, GFF, etc. MEM4WIN was able to change the mindset of the market, which was:
• a IG-unit thicker than 50mm has a short durability
• the glass industry want to sell tonnes of glass not m²
Now the production of tempered thin glass is growing. The standardization lowered the minimum glass sick-ness to get thin glass in use. People from the different parts of the value change are able to see the possi-ble improvement. The only fear was a high price of the product because of high cost for thin glass and tempering. However, the market will regulate the price in the near future. The potential to get in market is great.
For instance, one coverage describes the opinion of the market, which is written from Klaus Siegele and called “Durch Dick und Dünn – 4-fach Isolierglas, Irrweg oder Innovation.”. He wrote: “The next step from a triple glass to a quadruple glass is not only one sheet more. It changes the complete design of an IG-unit and gives the chance for integration of extra functions. The quadruple glazing is changing the production process and the functionality of an IG-unit. The thermally treated thin glass is changing the float glasses to membranes, reducing the weight and is responsible to absorb mechanical and thermally stress.”
However, to get a window product with quadruple IG-unit on the market right now is difficult. The price for a quadruple IG-unit within a state of the art frame costs 295 €/m², which is 31% more than a standard window like the Internorm KF410. Not every time the 31% extra costs can be argued with the better value of the IG-unit. Therefore, the “frameless” approach is very interesting: (1) for fixed glazing in facades and (2) for frameless openable windows.
A frameless construction has the best values and a 20% lower price because no frame is needed.
But some more certificates are still needed to be able to bring a frameless window with quadruple IG-unit on the market (e.g. a certificate for the use of a GFK bar in the sealing).
Therefore, the partners involved agree to continue the collaboration and to further develop the system (e.g. special fittings and the inner CFK bar, which connect the frameless window to the wall).
List of Websites:
https://web.archive.org/web/20190508103103/http://www.mem4win.eu/
Buildings are responsible for 40% of energy consumption and 36% of EU CO2 emissions. According to the Energy Efficiency Plan of the European Commission, the largest cost-effective energy saving potential lies in buildings. Directive 2010/31/EU on the Energy Performance of Buildings (EPBD) foresees that Member States should draw up national plans for increasing the number of nearly zero-energy buildings and the Commissions’ Lead Market Initiative “Sustainable Construction” aims at the development and growth of the sustainable construction market.
Windows are critical elements to control the energy performance of buildings especially for zero-energy buildings. It is of paramount importance to develop windows which show reduced U-value, weight and costs and certain features to control and harvest energy. Such a window will have a high impact in the window industry and will reduce greenhouse gas emissions as long as the window is affordable, can be used for residential and office buildings in every climate zone, for new constructions or in retrofitting of older buildings.
Therefore
(1) MEM4WIN developed a novel IG-Unit for quadruple glazing containing ultra thin glass membranes dedicated as frameless openable windows for direct application in facades. Due to this approach U-values of 0.3 W/m²K were achieved reducing weight by more than 50% and costs by 20%.
(2) MEM4WIN developed ink-jet printed organic photovoltaics (OPVs) and fully integrated solar thermal collectors for energy harvesting and micro mirrors for energy control and advances day lighting.
(3) Fabrication costs were further reduced by replacing conventional and cost intensive materials used for contacts like ITO and silver by graphene. MEM4WIN developed production methods like transfer printing and ink-jet printing to fabricate contacts for OPVs.
The developed technologies were integrated in several demonstrators. From 21st to 24th of October, 2014, MEM4WIN presented the preliminary MEM4WIN façade system and first prototyps of OPV-glass-glass modules and of micro mirror arrays at the „glasstec“, the world's largest trade fair for the glass industry and its suppliers, in Düsseldorf, Germany.
The final presentation of the modified MEM4WIN façade mock-up took place at "Frontale", a leading trade show for windows, doors and facades held in Nuremberg from 16th to 19th of March, 2016. MEM4WIN presented the modified façade mock-up at the exhibition booth of LiSEC and a quadruple IG-unit in a double wing terrace door with polymer frame at the VEKA exhibition booth respectively.
Following single exploitable results of the MEM4WIN project are described in the publishable summary in detail:
• Tempered ultra-thin glass membranes
• Frameless, openable window for application in facades
• Novel lamination techniques for fabrication of OPV glass-glass modules
• Quadruple insulated glass unit with novel spacer technology
• Solar-thermal collector (fully integrated in IG-unit)
• Doped CVD Graphene for direct transferred transparent contacts
• LPE graphene ink for printing on organic solar cells
• Micromirror Arrays for Smart Windows
• OPV ink for direct printed organic photovoltaic cells
Project Context and Objectives:
Introduction
In the future, windows will even supply energy and take on other intelligent functions that are crucial for the comfort of the building users: shading, light control, lighting, noise reduction.
The ‘window of the future’, which includes all of the above functions, was the scope of the MEM4WIN project (https://web.archive.org/web/20190508103103/http://www.mem4win.eu/).
The Austrian industrial company LiSEC – global leader in glass processing machines and a pioneer in the production of insulating glass – was coordinating the international research project. The project, which began on 1 October 2012 and had a run time of 42 months (project close: March 2016), was funded by the European Commission within the Seventh Framework Programme (project number: NMP3-SL-2012-314578). The following partners were involved in the project, in alphabetical order:
1.▪ Aixtron SE and Aixtron Ltd.
2.▪ Belectric OPV GmbH
3.▪ Consiglio Nazionale delle Ricerche / IMIP
4.▪ Durst Phototechnik AG
5.▪ Energy Glas GmbH
6.▪ Johannes Kepler University of Linz / ZONA
7.▪ Korea University / NMDL
8.▪ LiSEC Austria GmbH
9.▪ PROFACTOR GmbH
10.▪ Tiger Coatings GmbH and Co. KG
11.▪ The Chancellor, Masters and Scholars of the University of Cambridge / DENG / NMS
12.▪ University of Kassel / INA and CESR
Background
Buildings are responsible for 40% of energy consumption and 36% of EU CO2 emissions. According to the Energy Efficiency Plan of the European Commission, the largest cost-effective energy saving potential lies in buildings. Directive 2010/31/EU on the Energy Performance of Buildings (EPBD) foresees that Member States should draw up national plans for increasing the number of nearly zero-energy buildings and the Commissions’ Lead Market Initiative “Sustainable Construction” aims at the development and growth of the sustainable construction market.
Windows are critical elements to control the energy performance of buildings especially for zero-energy buildings. It is of paramount importance to develop windows which show reduced U-value, weight and costs and certain features to control and harvest energy. Such a window will have a high impact in the window industry and will reduce greenhouse gas emissions as long as the window is affordable, can be used for residential and office buildings in every climate zone, for new constructions or in retrofitting of older buildings.
Objectives
Therefore, MEM4WIN developed
(1) a novel IG-unit for quadruple glazing containing ultra thin glass membranes dedicated as frameless openable windows for direct application in façades. Due to this approach U-values of 0.3 W/m²K were achieved reducing weight by more than 50% and costs by 20%.
(2) ink-jet printed organic photovoltaics (OPVs) and fully integrated solar thermal collectors for energy harvesting and micro mirrors for energy control and advances day lighting.
(3) production methods like transfer printing and ink-jet printing to fabricate contacts for OPVs. So, fabrication costs were further reduced by replacing conventional and cost intensive materials used for contacts like ITO and silver by graphene.
Results
(1) LISEC introduced a novel IG-unit for quadruple glazing containing ultra thin glass membranes dedicated as frameless openable windows for direct application in façades. U-values of 0.3 W/m²K were achieved. The feasibility of tempering and integration of 0.9mm ultra thin glass membranes was demonstrated. However, the change in glass thickness in the final demonstrator from 0.9mm to 1.6mm for inner and middle panes is due to current availability of low-e coated glass. In near future availability of 1.3 mm glass will be given and can be considered. As outer laminate 2+2 mm tempered thin glass laminate was chosen in order to achieve given windload requirements.
Due to the use of tempered glass membranes (<0.9 mm) in a new frameless window design weight is reduced (50%). The new frameless window allows to be integrated in a façade without any visibility of the wing. Low distortions in the appearance of the façade was achieved due to asymmetric construction of the IG-unit.
(2) Several printed OPV modules were produced by BELECTIC OPV GmbH and integrated directly in a diffusion-tight glass-glass-encapsulation with edge sealing by LiSEC and therefore the modules are perfectly protected against environmental influences. A semiconductor ink with optimized jetting behavior was formulated by PROFACTOR (lab scale) and Tiger Coatings (upscaling) and OPV modules were inkjet printed with a total active area of 125 cm². In the next step OPV modules will be printed with an industrial inkjet printer, which combines perfect design-freedom with the ability to print very large areas. The industrial inkjet printer was developed by Durst. Apart from the MEM4WIN-project, OPV modules from BELECTRIC OPV were already used for the German pavilion at the World Expo 2015 in Milano, where stylised trees integrated with the OPV modules, which are embedded in a flexible film, provide shade for visitors and generate energy at the same time.
Miniaturizing lamella blinds down to micromirrors has some very obvious advantages: Beneath segmentability and the “uncut” outlook, they are protected between the window panes against wind, weather and dirt. But the miniaturization is beneficial as well to considerably improve the mechanical stability of such devices developed by University Kassel. The electric field between the mirrors and the electrode upon the pane will make the mirror switch. This makes those mirrors maintenance free for their whole lifetime.
(3) Concerning graphene research, the investigation and optimisation works have led to a reliable CVD process for the preparation of defect free graphene. Four layers of graphene were grown and doped by CNR on glass and showed a resistivity around 25 Ohm/sq and a transmittivity above 90%. Within the project, a new CVD tool was developed by AIXTRON. This new equipment is capable of producing 400cm2/h of monolayer graphene. The concept for this new system is fully scalable and could be used to produce very large area graphene > 1x1m.
First integration in OPV cell of graphene transferred on glass was realized. This attempt showed that with CVD graphene it is possible to make functional solar cells and that the optical density is good.
Furthermore, graphite was successfully exfoliated in water and additionally concentrated to produce a graphene ink with 1 mg/ml. Since for inkjet printing the graphene flakes have to be smaller than 1 µm and the ink has to fulfil certain other jetting and printing requirements, the ink was further optimized for inkjet printing concerning viscosity and boiling point with additives. This was then incorporated into inverted solar cells with an active area of 27 mm² by inkjet printing on glass/ITO/ZnO/P3HT:PCBM substrates in ambient atmosphere. Silver is used as top electrode. The cells showed efficiencies of up to 1.8 %.
The developed technologies were integrated in several demonstrators. From 21st to 24th of October, 2014, MEM4WIN presented the preliminary MEM4WIN façade system and first prototypes of OPV-glass-glass modules and of micro mirror arrays at the „glasstec“, the world's largest trade fair for the glass industry and its suppliers, in Düsseldorf, Germany.
The final presentation of the modified MEM4WIN façade mock-up took place at "Frontale", a leading trade show for windows, doors and facades held in Nuremberg from 16th to 19th of March, 2016. MEM4WIN presented the modified façade mock-up at the exhibition booth of LiSEC and a quadruple IG-unit in a double wing terrace door with polymer frame at the VEKA exhibition booth respectively.
A detailed description of following single exploitable results of the MEM4WIN project can be found at the MEM4WIN project website https://web.archive.org/web/20190508103103/http://www.mem4win.eu/ as well as in the publishable summary:
• Tempered ultra-thin glass membranes
• Frameless, openable window for application in facades
• Novel lamination techniques for fabrication of OPV glass-glass modules
• Quadruple insulated glass unit with novel spacer technology
• Solar-thermal collector (fully integrated in IG-unit)
• Doped CVD Graphene for direct transferred transparent contacts
• LPE graphene ink for printing on organic solar cells
• Micromirror Arrays for Smart Windows
• OPV ink for direct printed organic photovoltaic cells
Project Results:
1 Tempered ultra-thin glass membranes
1.1 The idea behind
The weight of a window could be reduced by 50 per cent through the use of tempered ultra-thin glass membranes as middle or inner pane within a triple or quadruple IG-unit (down to ~0.9mm). But todays tempered glass applications like solar modules or other weight and transmission sensitive applications are based on thinnest commercial available glass – 3.0 mm.
The reason is simply the physical limit on conventional tempering furnaces based on ceramic rollers as transport system; these rollers are arranged in a certain minimum distance but still glass with a temperature close to Tg (at 650 °C) tends to deformation when passing the free space between the rollers, thus creating so-called roller waves in tempered glass, being visible as uneven deflection known from reflecting facade.
A new approach of air cushion transportation within tempering furnaces enables tempering of thin glasses without any roller waves, proven today already in glass thicknesses down to 1.8 mm. These thin glasses are used preferably in new solar module applications, enabling weight reduction as well as higher transmission. This technology is patent pending by LiSEC and a few installations within Europe and Asia are already existent.
Tempered thin glass opens up new unparalleled possibilities. Lightweight, flexible and durable glass units without optical distortions and lower stress for the spacer system are ideally suited for use in modern architecture with highly energy-efficient windows/facades. Using tempered thin glass allows for considerably lighter modules with remarkably better thermal insulation values and increased lifespan.
1.2 Advantages
Due to the air cushion technology these developments allow to save energy for the tempering of up to 40%. The LiSEC air cushion system is ideal for surface-treated or double-sided coated glass sheets. The required energy is controlled by the air volume and can be immediately adjusted to a wide range of glass properties. (e.g. ultra clear, Low-E, Suncoat, enamel, etc.). No contact is made, which means there is no wear. Ceramic is a highly wear-resistant material. It distinguishes from conventional roller furnaces by
• The glass surface is not touched
• Air cushions are used instead of ceramic rollers
• Maximum convection in the circulation system
• Symmetrical energy input
The utilization of ultra-thin tempered glass membranes within highly energy efficient windows shows following advantages:
• Lower breakage losses due to thin glass sheets of enormous strength and flexibility
• Lower distortions in façade in the event of alternating climate loads due to adjustment of the inner panes to gas volume changes (while the outer pane remains in plane, because the outer pane is thicker in order to be able to carry the wind loads)
• Lower stress on spacer bars while climatic loads due to flexible tempered thin glass adjustment to gas volume
• Lower loads on fittings and frames due to weight reduction
• Improved working conditions for window construction employees
• Higher transmission (+1% for each mm glass thickness saved) (less absorption through thinner glass)
1.3 Results
With a new air cushion tempering furnace LiSEC demonstrated in experiments that the glass thickness could be reduced down to ~ 0.9 mm. The membrane effect of the flexible tempered thin glass sheet in the unit considerably reduces optical distortions of the thicker exterior glass (thickness regarding wind loads). Even with large temperature changes, the structure compensates for pressure fluctuations occurring in the unit.
2 Frameless, openable window for application in facades
2.1 The idea behind
A new frameless window design allows reducing considerably the weight of windows as well the visibility of frames in facades. Specially, architects are increasingly giving priority to uniform “reflection” in facades as well as to no visual difference between the glass facades and openable window wings.
Therefore window elements within full glass façade were chosen; only for this application a certain element needs to have this capability, where architectural aspects of uniform “reflection” are preferred and have to be considered.
So a parallel outbound opening was chosen to be useful, incl. motorized drive in order to avoid implementation of manual opening elements.
2.2 Advantages
The output of MEM4WIN will be an advanced, adjustable and affordable quadruple glazing window for zero-energy buildings. Due to the use of ultra-thin glass membranes (<0.9 mm) in a new frameless window design weight is reduced (50%). The new frameless window allows to be integrated in a façade without any visibility of the wing.
2.3 Results
The openable wing is not visible in the façade and there are low distortions in the appearance of the façade due to asymmetric construction of the IG-unit. This was shown with the presented exhibit at the Glasstec 2014 showed.
3 Novel lamination techniques for fabrication of OPV glass-glass modules
3.1 The idea behind
Traditional PV technologies are well established in roof top or solar park applications but are not appropriate for integration into facades, shading elements or windows. Lifetimes of more than three years have been demonstrated for flexible modules. Accelerated lifetime tests predict lifetimes of more than fifteen years for glass encapsulated modules. With the new sealing technique which will be developed by LIS during the project we expect to achieve a durability of solar cells up to 30 years since the OPV will be encapsulated 700 times tighter than ever achieved so far.
3.2 Advantages
Integration of solar modules into insulating windows will lead to a mutual benefit: on one hand, the windows will be provided with functionality. On the other hand, OPV modules will be isolated from water and oxygen for up to 30years, which will greatly enhance their stability. The Lisec lamination technology with additional diffusion-tight edge sealing and the Krystalflex encapsulation foil protects OLED very well against environmental conditions.
3.3 Results
The several printed OPV modules produced by Belectric OPV GmbH are directly integrated in a diffusion-tight glass-glass-encapsulation with edge sealing and therefore the modules are perfectly protected against environmental influences. It was produced in a newly developed vacuum lamination process by LiSEC for glass-glass-laminates with edge sealing. Accelerated lifetime tests predict a lifetime of 30 years since the modules have been encapsulated with a water vapour diffusion tightness of 0.01 g/m²day. This value is 700 times better compared with lamination foils of conventional open module edge glass-glass modules.
The novel vacuum lamination technology has been designed especially for PV module encapsulation and is characterised by gentle pressing and extremely short cycle times. Pre-lamination with this vacuum lamination process takes just about 3 to 5 minutes. Since curing is performed in a separate cycle, the laminator no longer is the bottleneck in PV module production.
4 Quadruple insulated glass unit with novel spacer technology
4.1 The idea behind
New legislative regulation for further improvements are in progress creating demand for further improved Ug-values, thus new design and manufacturing processes, materials and technologies are required. Since a simple step toward quadruple IG units is not feasible, these new challenges must be overcome like
- increase of weight due to 4 glass layers
- higher heat transition by higher amount of edge materials/sealant
- mechanical instability of edge connection between 4 glass layers
- lower light transmission with each additional glass sheet
4.2 Advantages
MEM4WIN will introduce a novel IG-Unit for quadruple glazing containing ultra thin glass membranes dedicated as frameless openable windows for direct application in facades. Due to this approach U-values of 0.3 W/m²K can be achieved reducing weight by more than 50% and costs by 20%.
The new quadruple insulated glass unit with novel spacer technology reduces weight and costs and lowers the U-value further (down to 0.3 W/m²K)
4.3 Results
The change in glass thickness from 1 mm to 1.8 mm for inner and middle panes is due to current availability of low-e coated glass. In near future availability of 1.3 mm glass will be given and can be considered. As outer laminate 2+2 mm glass laminate was chosen or also thicker glasses depends on the local situation to achieve required windload requirements. New calculations of the U-value show that the spacer filled with Argon gas can be reduced from 22 to 20mm, which helps to fulfill the requirements of profile manufacturers for less broad profiles.
5 Solar-thermal collector (fully integrated in IG-unit)
5.1 The Idea Behind
The idea is to give the insulation not only the function of saving energy, but also to produce energy!
In Europe about 50% of the energy for the heating of buildings to be expended, therefore we want to reduce this demand in the form of solar thermal energy. Solar thermal collectors for energy harvesting are fully integrated in the IG-Unit.
The application in gas-tight insulation provides an ideal prerequisite for this type of collector.
The structures are not thicker than insulating, therefore allows the collector into existing mullion / transom constructions install.
5.2 Advantages
• Low panel thickness compared to conventionally flat plate collectors
• Energy losses reduced by insulating properties (gas-tight and low-e coating)
• Built in the facade 90 degrees with good optical appearance
• Improved energy efficiency in the transitional months
5.3 Results
Energy Glas has produced a gas-tight quadruple insulating glass collector with Lisec technology. The collector works and with improved performance data as a normal flat plate collector. It has better energy harvest in the transitional months and a very good optical properties of the collector for the façade. The insulating collector is gastight and flexible dimensions and special shapes are possible.
6 Doped CVD Graphene for direct transferred transparent contacts
6.1 The idea behind
The objective is to replace indium tin oxide (ITO), which is the common material used as transparent conductive layer in electrical device, by graphene synthesised via chemical vapor deposition (CVD) and the use of a roll to plate process for the transfer. Graphene has a higher transparency than ITO and is a promising candidate for cost reduction, and for overcoming the shortage of indium supplying. Especially the roll to plate process that will be developed within the project is an easy and fast process to transfer CVD graphene from copper foils onto glass and will make it possible to handle graphene layers for mass production. The specific goal within MEM4WIN will be to fabricate large area CVD graphene, transfer it to glass and use it for OPVs, Micro Mirrors and OLEDs.
6.2 Advantages
Graphene layers should be capable of meeting the required minimum conductivities of 10-5 S.cm-1 (for charge extraction layers) and area conductivities of 0.05 S.cm-1 (for electrodes) while still providing transparencies of more than 80% over the whole visible and near infrared region.
6.3 Results
Within the framework of the MEM4WIN project we successfully achieved the transfer on glass plate of CVD graphene grown on copper. The investigation and optimisation works have led to a reliable CVD process for the preparation of defect free graphene. The developed transfer process has enabled the preparation of graphene on glass at lab scale. Four layers of graphene were grown and doped by CNR on glass and showed a resistivity around 25 Ohm/sq and a transmittivity above 90%.
To enable large scale applications for graphene, all tools used for material growth and transfer needs to be scaled up. Within the project, a new CVD tool was developed. This new tool allows a significant throughput increase for the production of high quality monolayer graphene. This new equipment is capable of producing 400cm2/h of monolayer graphene. The concept for this new system is fully scalable and could be used to produce very large area graphene > 1x1m.
First integration in OPV cell of graphene transferred on glass was realized. This attempt showed that with CVD Graphene it is possible to make functional solar cells and that the optical density is good. The OPV cell tested consisted of a layer stack of ZnO, P3HT:PCBM, and HIL were coated and a 300 nm Ag electrode was evaporated. The first trial gave 40%FF and 0.8% efficiency, which is very promising. With the optimized transfer process and with graphene doping, a stable sheet resistance of 35 Ohm/sq at a transparency of 90,2% were obtained with a 4-layer-graphene sample (5x5cm).
7 LPE graphene ink for printing on organic solar cells
7.1 The idea behind
Graphene can be produced by methods like growth on metal substrates by Chemical Vapor Deposition (CVD) or annealing SiC substrates [1]. However, for industrial applications also Liquid Phase Exfoliation (LPE) is a prominent way for a high-yield production of graphene flakes [2] (Figure 1). In this process a dispersion of graphene in a solvent is obtained that can be used as ink for inkjet printing (Figure 2). The top electrode in organic photovoltaic (OPV) solar cells is usually silver deposited by thermal evaporation [3]. Our goal was to replace the silver grid by an inkjet printed graphene pattern.
A common solvent for LPE of graphite is N-methyl-pyrrolidone (NMP) [4]. However, it is forbidden to use with most of the print-heads, obviously, due to its high dissolution power. Moreover the reproduction toxicity of NMP can reduce the working place safety.Several suitable solvents for printing were investigated [5]; however, no organic solvent based graphene ink could combine all requirements: stability, compatibility with the substrate and high conductivity. Therefore it was decided to focus on the printing of graphene as hole-transport-layer (HTL). The HTL is the underlaying layer underneath the top electrode (Figure 3) and enables the transport of holes towards the top electrode and blocks electrons due to the favorable energy level.
7.2 Advantages
PEDOT:PSS, a transparent, conductive polymer, is widely used as HTL. However, due to its sensitivity to moisture and oxygen its use leads to limited life times even for encapsulated cells [6]. To improve stability we replace the PEDOT:PSS by inkjet printed graphene. Water can be now chosen as solvent since it is compatible with the underlying active polymer in bulk-heterojunction solar cells. Furthermore, water is compatible with print heads, low-cost and ecologically harmless.
7.3 Results
Graphite is successfully exfoliated in water and additionally concentrated to produce a graphene ink with 1 mg/ml. For inkjet printing the graphene flakes have to be smaller than 1 µm and the ink is further optimized for inkjet printing concerning viscosity and boiling point with additives. This is then incorporated into inverted solar cells with an active area of 27 mm² by inkjet printing on Glass/ITO/ZnO/P3HT:PCBM substrates in ambient atmosphere. Silver is used as top electrode. The cells showed efficiencies of up to 1.8 %.
Up-scaling processes and optimization of the ink are currently under investigation.
7.4 References
[1] F. Bonaccorso, A. Lombardo, T. Hasan, Z. Sun, L. Colombo, A.C. Ferrari, Materials Today, 15 (2012) 564-589.
[2] Y. Hernandez, V. Nicolosi, M. Lotya, F.M. Blighe, Z. Sun, S. De, I.T. McGovern, B. Holland, M. Byrne, Y. Gun’ko, J. Boland, P. Niraj, G. Duesberg, S. Krishnamurti, R. Goodhue, J. Hutchinson, V. Scardaci, A.C. Ferrari, J.N. Coleman, Nature Nanotechnology, 3 (2008) 563-568.
[3] B. Ma, C.H. Woo, Y. Miyamoto, J.M.J. Fréchet, Chem. Mater., 21 (2009) 1413-1417.
[4] F. Torrisi, T. Hasan, W. Wu, Z. Sun, A. Lombardo, T.S. Kulmala, G.-W. Hsieh, S. Jung, F. Bonaccorso, P.J. Paul, D. Chu, A.C. Ferrari, ACS Nano, 6 (2012) 2992-3006.
[5] J. Kastner, I. Gnatiuk, B. Unterauer, I. Bergmair, O. Lorret, G. Hesser, K. Hingerl, D. Holzinger, M. Mühlberger, Imaginano Conference (2013), Bilbao, Spain.
[6] K. Norrman et al. J. Am. Chem. Soc. 132, 16883 (2010)
8 Micromirror Arrays for Smart Windows
8.1 The idea behind
Daylighting in general should be preferred above electric lighting. It is free and characterized as a high illuminance with full-spectrum light which gives a perfect color rendering, variable angles of the light incidence, as well as a big variation in intensity and colors, which gives a positive effect on human well-being. Daylight can also offer a favorable thermal energy inside the buildings. However, daylight can also produce uncomfortable solar glare and very high luminance reflections e.g. on display screens, both of which interfere with good vision.
This problem can be met by a flexible system, which can fit the requirements of daylight illumination, glare protection and heat regulation all at the same time. In order to overcome these problems, millions of micromirrors can be implemented in the interspace of conventional insulation glasses, providing efficient transmission control and significantly improved daylight distribution. Such micromirrors have a size of less than 0,1mm², which means about 12 mirror elements / mm² or 12.000.000 mirrors / m².
8.2 Advantages
Miniaturizing lamella blinds down to micromirrors has some very obvious advantages: Beneath segmentability and the “uncut” outlook, they are protected between the window panes against wind, weather and dirt. Furthermore the miniaturization is beneficial as well to considerably improve the mechanical stability of such devices. The electric field between the mirrors and the electrode upon the pane will make the mirror switch. This makes those mirrors maintenance free for their whole lifetime.
8.3 Results
In principle, the fabrication of micromirrors can be summarized in three steps: deposition of thin-film layers, micropatterning to define the mirror shape and release of the mirror using a self assembling step, in which the mirrors will stand up in a nearly 90⁰ out-of plane position making use of the intrinsic stress of the deposited layers. Within MEM4WIN project, at University of Kassel micromirror arrays of the size of 10 by 10 cm² have been fabricated showing <1 mW/m² power consumption in holding position and at least 75% and 2% transmission (open and closed).
9 OPV ink for direct printed organic photovoltaic cells
9.1 The idea behind
Traditional PV technologies are well established in roof top or solar park applications but are not appropriate for integration into facades, shading elements or windows. Solutions based on thin film technologies exist but are merely "building attached" rather than fully integrated into the building components and are thus not competitive, due to high costs and insufficient flexibility. Moreover, the traditional thin film systems do generally not meet the legal requirements for façade integrated systems. Most important, they do not offer any degrees of freedom in terms of design, as they are not easy to be tailored with respect to colour or transparency.
Organic photovoltaics are a promising alternative to traditional PV technologies, as they meet all of the requirements described above.
9.2 Advantages
Organic Photovoltaic Modules are due to their outstanding properties, such as
- semi-transparency
- light weighted
- availability of different colours
- design-freedom,
extremely suitable for the integration in glass and thus for the BIPV (Building Integrated Photovoltaics).
9.3 Results
Several printed OPV modules were produced by BELECTRIC OPV GmbH and integrated directly in a diffusion-tight glass-glass-encapsulation with edge sealing and therefore the modules are perfectly protected against environmental influences. An optimized semiconductor ink was developed by PROFACTOR (lab scale) and Tiger Coatings (upscaling) and OPV modules were inkjet printed with a total active area of 125 cm². In the next step OPV modules will be printed with an industrial inkjet printer, which combines perfect design-freedom with the ability to print very large areas. The industrial inkjet printer was developed by Durst . Apart from the MEM4WIN-Project, OPV Modules from BELECTRIC OPV were already used for the German pavilion at the World Expo 2015 in Milano, where stylised trees integrated with the OPV modules, which are embedded in a flexible film, provide shade for visitors and generate energy at the same time. A second shading system was installed in Addis Ababa for the Peace and Security Building of the African Union in the shape of the African continent.
Potential Impact:
The main potential impact of the MEM4WIN project is to replace double and triple IG-units with quadruple IG-units for increasing the energy efficiency of buildings.
Beside the novel quadruple IG-unit within MEM4WIN also other technologies were developed. All in all a number of 30 technology prototypes were realized to demonstrate the reached performance of the single technologies. The description of performance with could be reached with these demonstrators are included in the respective WP-descriptions in the periodic report (m42) as well in deliverable report D8.2.
For instance, we were able to reach the estimated U-value of 0.3 W/m²K and the weight reduction of 50% to 26,5 kg/m². For the cost reduction we had estimated values for the starting value with 117,55 €/m² and for the goal with 93 €/m². As the final cost comparison shows, we reached the estimated reduction of 20% to a standard state of the art window with 175 €/m².
We were able to get the technical performance to replace a CVD Graphene with an ITO, but we were not able to get it done at the estimated costs. The technical potential is now not exhausted. For the graphene ink, we were able to achieve the estimated price, but we were not able to get the performance we need to replace the silver ink. The electrical performance was only reachable when the ink was black, but it should be trans-parent.
As the final Life Cycle Assessment (LCA) shows, we were able to reach a heating demand of 12 kWh/m²a. The cooling energy demand is equal to rooms, equipped with 3-IG windows. Therefore, the estimated value of 30 kWh/m²a can be assumed as reached. The energy demand for lighting is equal to rooms, equipped with 3-IG windows (equal g-value, TL-value). As well the energy demand for office equipment is equal to rooms, equipped with 3-IG windows, because the value is not affected by windows. Therefore, the estimat-ed value of 20 kWh/m²a can be assumed as reached.
To Reduce Embodied Energy we got thinner glass in use. Therefore we were able lower the value from a 4mm float glass of 9,85 kg CO2-eq/m² to 6,74 kg CO2-eq/m² of a thermally treated 1,8mm glass. In a sec-ond step we were able lowering it down to 5,44 kg CO2-eq/m² with the use of a thermally treated 0,9mm glass, see D2.4. In the end, we were able to reduce the GWP between 32% (1,8mm) and 45% (0,9mm).
Dissemination activities within the MEM4WIN project covered activities that informed interested parties about the MEM4WIN project in general, the scientific results and the products/processes developed within the project. The interested parties get informed about the project via the project website and the project presentation (ppt-slides). The scientific results get disseminated via conference contributions (77 contribut-ed talks) and via scientific journals (32 peer reviewed publications) mainly. The developed prod-ucts/processes were presented at fairs and trade shows like at glasstec 2014 and Frontale 2016.
Furthermore, due to presentations of the novel quadruple IG-unit using world's leading communication chan-nels for the glass and window e.g.
• Glass technology Live at glasstec 2014 incl. proceedings
• GDP 2015 incl. proceedings
• CTC 2015 in Pecking
• Interviews in the magazine Glasswelt 12/2015 with UKA (Ulrich Neumann) and ENG (Mirco Franke and Elmar Dohmann)-the professionals in the glass and windows industry get informed about the fact that novel tempered thin glass makes quadruple IG-units with high durability possible. Glass technology journals like ‘Glaswelt’ re-ported frequently. As the comments and articles in the journals show, MEM4WIN initiated a lively debate about advantages and disadvantages of quadruple IG-units. A selection of those articles can be found in the download section of the MEM4WIN website: https://web.archive.org/web/20190508103103/http://www.mem4win.eu/
Exploitation activities covered for instance the presentation of results at fairs like the preliminary façade mock-up and technology prototypes at the glasstec 2014. The updated façade mock up was presented at the Frontale 2016 with quadruple IG-units (Ug-value = 0.3 W/m²K), frameless open-able window, solar-thermal collector, OPV and OLED modules integrated with the novel lamination technology.
The technologies, which were presented, are ready for marketing. Technologies, which have been developed during MEM4WIN project but are not ready for marketing yet like Micromirrors, CVD-Graphene, LPE Gra-phene, inkjet printed OPV, ... have not been included in order to avoid the trap of raising excessive cus-tomer expectations at the commercial fair.
Already during glasstec 2014 we received a great feedback from architects, façade planer, glass Industry, IG-unit producer, profile producer, window producer and façade manufacturer. Most of them see that MEM4WIN was able to solve the right problems, which will help them to get new products into the market. An IG-unit with U-value of 0.6 W/m²K is getting to the standard. At the same time, the market is waiting for the next generation. Will it be the vacuum glazing or could it be only one sheet extra? At the glasstec 2014 the experts were able to get an impression about the advantage of thin glass in an IG-unit. The old mindset of the market to use only thick float glass for the IG-unit was starting to change.
A big factor for driving this issue is the weight reduction, which helps everybody in the value chain. Right now it will be most important for the plastic profile manufacturer because with the existing constructions the reached the weight limits already. Visitors saw also a potential for the thermally treated thin glass in the use of cold bended glass, fire safety glass, OLED glass-glass modules for handrails and so on.
Furthermore, the quadruple IG-unit provoked reaction in the media like journals Glaswelt, GFF, etc. MEM4WIN was able to change the mindset of the market, which was:
• a IG-unit thicker than 50mm has a short durability
• the glass industry want to sell tonnes of glass not m²
Now the production of tempered thin glass is growing. The standardization lowered the minimum glass sick-ness to get thin glass in use. People from the different parts of the value change are able to see the possi-ble improvement. The only fear was a high price of the product because of high cost for thin glass and tempering. However, the market will regulate the price in the near future. The potential to get in market is great.
For instance, one coverage describes the opinion of the market, which is written from Klaus Siegele and called “Durch Dick und Dünn – 4-fach Isolierglas, Irrweg oder Innovation.”. He wrote: “The next step from a triple glass to a quadruple glass is not only one sheet more. It changes the complete design of an IG-unit and gives the chance for integration of extra functions. The quadruple glazing is changing the production process and the functionality of an IG-unit. The thermally treated thin glass is changing the float glasses to membranes, reducing the weight and is responsible to absorb mechanical and thermally stress.”
However, to get a window product with quadruple IG-unit on the market right now is difficult. The price for a quadruple IG-unit within a state of the art frame costs 295 €/m², which is 31% more than a standard window like the Internorm KF410. Not every time the 31% extra costs can be argued with the better value of the IG-unit. Therefore, the “frameless” approach is very interesting: (1) for fixed glazing in facades and (2) for frameless openable windows.
A frameless construction has the best values and a 20% lower price because no frame is needed.
But some more certificates are still needed to be able to bring a frameless window with quadruple IG-unit on the market (e.g. a certificate for the use of a GFK bar in the sealing).
Therefore, the partners involved agree to continue the collaboration and to further develop the system (e.g. special fittings and the inner CFK bar, which connect the frameless window to the wall).
List of Websites:
https://web.archive.org/web/20190508103103/http://www.mem4win.eu/
