Project Progress
Eensulate Module
EENSULATE curtain wall modules where the thermal and acoustic insulation are provided TE glass based on VIG technology and EENSULATE foam (TCF) in the spandrel combined with SoA low-e coated glass, including thermo-chromic coated glass with additional self-cleaning and antifogging functionalities. 
Vacuum Insulated Glass (VIG)
A number of prototype VIG samples have been fabricated at Ulster University using seal materials developed by SAES. These included a hot melt type polymer and an epoxy resin. Initial trials wereconducted on small scale (300x300mm) samples to determine appropriate application techniques, processing criteria including heating schedules for temperature and time and application of pressure. Initial samples used annealed glass with or without a hard low-e coating. Larger size 500x500mm samples have subsequently been fabricated from 6mm thick fully tempered glass using a combination of uncoated and soft low-e coated glass. Based on modelling results, an array of stainless steel support pillars, 0.4mm in diameter, 0.2mm high and spaced on a 50mm regular grid maintains the separation of the glass panes. Initial prototype fabrication has proved successful and further work will concentrate on refinement of the assembly technique and processing criteria.
Eensulate Sealant
Four sealant classes have been investigated:
1. THERMOPLASTIC POLYOLEFINS
2. POLYISOBUTYLENE
3. POLYSULFIDE
4. EPOXY RESINS
Current achieved permeability is 10-1 barrer, while target permeability is 10-2/10-3 barrer achievable through filler addition and chemical modifications.
EENSULATE sealant is a mono-component epoxy resin dispensable in the range 60 - 100 °C. The thermal curing allows low processing temperature (below 200 °C). The resin has extremely high barrier performance for Ar, N2 and O2 (till two orders of magnitude better than commercial sealants for insulating glasses). The sealant contains also an active filler for moisture absorption. The resin has high yield stress and adhesion strength (> 7MPa) on glass surfaces. It can be processed in air and deposited by an automatized system working with precise erogation.
Eensulate Getter
Three getter families habe been investigated:
1. ZEOLITES
2. Zr - ALLOYS
3. Li - ALLOYS
Current focus on Zr-ALLOYS is configured as a tape.
The EENSULATE getter comprises a Zirconium based alloy under the tradename ZAO® 2, with Nitrogen sorption capacity, superior than state of art getter solutions for VIG. It is delivered in form of laminated double-side getter strips (200 m thick and 8mm large) that allow easy handling and positioning in air. Getter is activated by radio frequency heating under vacuum pumping.
Eensulate One-Component Foam and Two-Component Foam
We are developing two kinds of EENSULATE foam in the project:
One-component foam (OCF) and Two-component foam (TCF). The OCF will be used as an effective thermal sealant between curtain wall and sub-structures, comprising a bittering agent that will prevent small animals and insects from eating and destroying the foam in the cavities. The polyurethane foam is packaged in a pressurized can and can be easily used in construction sites.
Why is it beneficial?
EENUSLATE OFC has improved re behavior thanks to the use of nanosized inorganic fi llers and expandable graphite which ensure a high level of re resistance. The experience from two-component foam was transferred to increase the re properties and removing toxic compound (e.g. halogen molecules).
TCF is highly insulating polyisocyanurate (PIR) foam based insulating material enhanced with eco-friendly lamellar inorganic fillers, that contributes to meet energy performance requirements, environmental challenges and cost reduction without undue compromise of the overall building re safety. The TCF is used to be injected workable for the manufacturing of spandrel replacing cut-to-measure mineral wool panels.
Why is it beneficial?
The advantages of the TCF system during the production system are the increased efficiency of 35 kg/m3 and ease of the processing. PIR system with layer fillers also provides re reaction properties because of favor the formation of a reinforced layer, providing an effective barrier against heat and oxygen, release non-flammable gases, and at the same effectively suppress smoke and gases during the combustion process.
EENSULATE glass prototypes
EENSULATE small scale prototype assembly and preliminary tests
The assembly process for the small-scale VIG prototypes (500mm by 500mm) required a significant and sustained effort by two project partners, namely ULSTER and SAES, culminating in the achievement of the project performance goals and the definition of a reliable process protocol ready for technology transfer for large scale production. The partners faced many challenges unforeseen at the outset, however this research has generated extensive knowledge and understanding of the complex range and interaction of parameters required for VIG production.
A number of significant challenges have been encountered and addressed in the latter project months, namely the application and processing of the polymer based resin edge sealant, the incorporation and activation of the gettering system used to maintain the required vacuum pressure over the glazing lifespan and sealing of the pump-out hole through which evacuation of the VIG is achieved.
Two approaches were investigated for the application of the polymer edge sealant:
- Needle dispensing by a semi-automated two-axis equipment loaded with sealant syringes kept at a temperature range of 60°C to 80°C;
- Manual application of a sealant-based preformed solid strips.
The main challenge in this process concerned the uniformity of the sealant deposition due to its high-viscous behaviour, highly dependent on process conditions (i.e. temperature and pressure). The deposition and process parameters were fine-tuned and optimized through an intensive testing campaign in Ulster and SAES labs.
The second technology-enabling component is a getter system consisting in a secondary internal framework of getter-based strips to counteract the effects of the edge semi-permeability and the outgassing of glass surfaces and VIG components. The getter solution is based on double-coated metallic strips with a Zr-based getter alloy. The getter strips are held in position with magnets during the VIG assembly and evacuation processes after which the getter requires a thermal activation process to remove the passivated surface oxide layer. This process has been achieved by means of radio-frequency heating that was optimised for the VIG configuration with a suitable design of induction coil and control process parameters.
Finally, the pump-out hole required a customised sealing process which would not affect the performance of the polymer edge seal nor the tempered glass and which could be undertaken under medium to high vacuum pressures. This was achieved using the ultrasonic soldering of metal films to the glass surface in the region of the pump-out hole and to a metal or glass cover disc. Heating of this region under vacuum at the end of the evacuation process enabled the reflow of the bonded metallic films on the glass and cover disc which subsequently sealed the pump-out hole upon cooling and solidification.
The thermal performance of the fabricated prototypes was evaluated in a guarded hotbox calorimeter. A centre-of-pane U-value of 0.36 Wm-2K-1 and an overall U-value of 0.44 Wm-2K-1 has been successfully achieved. This is a significant accomplishment in the development of such a novel and innovative approach to VIG production.
EENSULATE façade modules
Calibration of the EENSULATE dynamic performance
To face the increasingly urgent need to reduce the energy demand in buildings, the Eensulate Project proposes a glazed façade system based on VIG technology coupled with a thermochromic coated glass, the EENSULATE curtain wall module. Thermochromic thin film has become a recognized potential solution for the reduction of the solar radiation entering into a glazed system due to its intrinsic ability to modulate the solar heat gain of the glass as a function of its temperature. This “intelligent” property of the thermochromic film distinguishes the insulation nature of the window from any other passive solution, like VIGs that have the same degree of insulation whatever the ambient temperature. On the contrary, the thermochromic window has a dynamic behavior as it allows or not the solar radiation entering through the glazed facade depending on the temperature reached by the thermochromic coating. In fact, below a certain temperature, called switching temperature, the coating allows solar radiation entering the building while above this temperature the solar radiation is reflected outside preventing indoor overheating. From previous investigations, it is known that thermochromic material properties (switching temperature, hysteresis gradient and width) can be altered through variation of synthetic route, mainly by acting on the material doping. However, no attention has been paid to how such alterations affect the overall building energy performance and the consequent savings attributed to the materials.
Energy building simulation have been performed considering the effect of the first thermochromic system developed within the EENSULATE Project on the energy saving against both clear glass systems and the VIG EENSULATE module. The simulations have as input the optical properties (visibile and solar reflectance and transmittance) of the thermocromic glass provided by UCL and measeured in the UNIVPM laboratory. Those properties have been considered as baseline from which the simulation starts. By changing the switching temperature and minimising the building energy consumption the optimal thermochromic configuration has been retrieved.
Workflow of the experimental and simulation activity
The simulations have been run for different latitudes, with different levels of direct incident solar radiation (Italy, Poland and United Arab Emirates). The simulation tool developed has been then exploited to drive the design of the final thermochromic coating in order to maximize the potential energy saving by identifying the optimal switching temperature and magnitude for the different geo climate areas.
A measurement system has been designed for the evaluation of the façade performances and room comfort indices and it has been calibrated in the FOCCHI Testing Lab, a room mock up presenting one wall entirely glazed. In the Testing Lab a heat pump is installed whose operation can be controlled based on room air temperature and whose consumption can be monitored and registered. The parameters required to be monitored for assessing the façade performances and the mock-up comfort can be clustered as follows:
- Glazed façade thermal and visible transmittance
- Thermo-hygrometric parameters
- Energetic parameters
- Comfort parameters
