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At least 19 records

Self-Healing Films for Vacuum Insulation Panels (Final Report)

Vacuum insulation panels (VIPs) have an extremely high thermal resistance of around R35/inch, which makes them ideal for building envelope retrofits and prefabricated construction with space constraints. However, the barrier film that maintains the vacuum and thermal performance of the panel can be easily damaged during transportation, installation, and service life. Oak Ridge National Laboratory (ORNL) has developed a self-healable barrier film for VIPs that instantly self-heals damages caused by punctures. The multi-layer barrier film is manufactured using roll-to-roll (R2R) methods. The self-healing barrier film prevents loss of vacuum in VIPs and maintains the exceptional thermal insulation performance. Enhanced durability of VIP by self-healable barrier film and establishing the commercialization path will increase the use of VIPs, thus reducing overall energy usage of buildings. This project has fine-tuned the slurry chemistry of the self-healing components and transitioned the R2R manufacturing trials from mid-scale lab equipment to large-scale industrial equipment for de-risking the technology for commercialization with our TCF CRADA partner, FLEXcon.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

The effect of barrier films and exposure on the aging of vacuum insulation panels with fumed silica cores

Vacuum insulation panels have very low thermal conductivities compared to conventional insulation materials. The reduction of the core pressure significantly lowers gas phase conduction and overall thermal conductivity. As a consequence, increases in gas pressure can significantly increase thermal conductivity of the VIP. In addition, the thermal conductivity of the core is sensitive to moisture content. For vacuum insulation panels with fumed silica cores, work shows that the measured thermal conductivity increases by 0.5 x 10-3 W/mK per mass percent increase in water content [1]. This is significant since the thermal conductivity of vacuum insulation panels with fumed silica cores is in the range of 0.004 W/mK. This work investigates the long-term behavior of vacuum insulation panels comprised of fumed silica cores with polymer (ethylene vinyl alcohol) and metalized (aluminized) barrier films exposed to different exposure conditions: ambient conditions; exterior conditions in a mixed humid climate; and 24oC and 80 percent relative humidity. Results show that the increase in thermal conductivity is more pronounced for vacuum insulation panels made using polymer barrier films compared to the same panel protected by a metalized film. The increase is more pronounced when exposed to high relative humidity, 80 percent. After almost two years exposure, the decrease in thermal conductivity for vacuum insulation panels protected by a metalized barrier films are between 4 and 11 percent depending on exposure condition. The smallest decrease is for ambient conditions where the largest decrease is for exposure to 80 percent relative humidity. Similar behavior was observed for panels protected using polymer films, except the decrease in thermal conductivity was significantly higher, between approximately 20 and 60 percent, in the same order as for panels protected by metalized films. Measurements are ongoing with an attempt to develop a better relationship between these types of tests and vacuum insulation panel service life.

Aldykiewicz Jr, Antonio↗

Next generation retrofit wall panels with integrated vacuum insulation panels

Approximately two-thirds of residential buildings in the United States were constructed before the Department of Energy established energy conservation measures. These buildings present major opportunities for improving energy efficiency, though retrofitting them remains technically and economically challenging. This study presents the development and the durability evaluation of an innovative retrofit panel system that integrates vacuum insulation panels (VIP) with a nail-base panel (called a retrofit insulated panel) to enhance thermal performance with minimal disruption to occupants and without altering standard nail-based panel installation practices. Hygrothermal simulations were conducted to assess the moisture behavior of wall assemblies before and after retrofit installation under varying water vapor control strategies and climate conditions. Results indicate that, with appropriate moisture control strategy, the retrofit system effectively prevents moisture accumulation, keeping mold index values and relative humidity levels below critical thresholds. Additionally, Guarded Hot Box testing was performed to compute the effective R-value of the panel under different coverage areas that demonstrates its effectiveness in enhancing both thermal and moisture performance in existing residential buildings.

Iffa, Emishaw [ORNL]↗

Long term performance of vacuum insulation panels integrated into building components

Vacuum insulation panels provide much greater resistance to heat transfer than conventional insulation materials, making them ideal for building applications, especially where space is a constraint. Of particular interest is energy retrofits where high insulation values are required with very little or no modifications to existing building envelope elements such as fenestrations and service penetrations. To facilitate the use of vacuum insulation panels (VIPs) in residential and commercial construction, this study investigates the performance of VIPs integrated into polyisocyanurate foam board and vinyl siding after several years of service. Vacuum insulation panels integrated with polyisocyanurate boards were studied in mixed humid and cold climates. The integration of VIPs with vinyl siding was investigated in a mixed humid climate. Periods of service were between two and five years. In all cases, the integrated building components outperformed conventional materials by almost 40 percent during heating and cooling periods. However, the percent reduction in heat gains and losses of the integrated building components decreased with time at a rate between approximately 4% and 10% per year during the service period. In some cases, the rate seems to converge to a steady -state value. Measurements are ongoing to determine if a steady-state value is attained or the panel's insulation value continues to decrease with time. This study is critical in addressing the service life and durability of the building envelope with VIP integrated building components. The effect of these changes will be reviewed in the context of an exterior retrofit.

Aldykiewicz Jr, Antonio↗

Self-healing barrier films for vacuum insulation panels

A self-healing vacuum insulation panel and a method of manufacture are provided. The vacuum insulation panel includes a self-healing, multi-layer barrier film including a separator between a curing agent and a curable resin. Upon damage to the separator, the curing agent penetrates the separator due to a pressure differential across the barrier film and reacts with the curable resin to seal any cuts or punctures. The curing agent and the curable resin can be selected to have long term stability and a short reaction time with no need for external stimuli. As a result, the multi-layer barrier film can retain the internal vacuum and maintain a desirably low thermal conductivity using low-cost, commercially available epoxies and curing agents.

Biswas, Kaushik↗

Nanoporous Wood Chips Based Sizable, Robust, and Low-Cost Honeycomb Vacuum Insulation Panels (DOE BENEFIT Final Research Performance Progress Report (RPPR))

Conventional vacuum insulation panels (VIPs) suffer from severe limitations including high cost, vulnerability to perforation, and significant performance degradation over time due to vacuum loss. InventWood Inc. (IW) and partnering teams completely re-engineered the VIP structure by constructing arrays of isolated vacuum-cells to enable limited cutting at designated areas (in between vacuum cells) and reduced consequential vacuum loss due to puncture. The teams also replaced the expensive vacuum insulation core materials with a low-cost commercial wood pulp and recycled long fiber. The wood pulp derived VIP can deliver an overall panel insulation of R15 (<0.01W/m·K) with over 90% thermal resistance retention after cutting (R13.5 overall, R5 along the cut edges). In addition, the vacuum-cell-array design minimizes edge losses, resulting in more durable performance, longer service life (>50 years), and higher R-value per dollar towards a cost target of <$1/ft 2 ·in. It is anticipated that the Nanochip-VIP will attract strong market interest and become an affordable insulation solution for energy efficient buildings and retrofits, leading to significant reductions in energy usage.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Natural fibers as promising core materials of vacuum insulation panels

To reduce energy consumption in buildings, this paper investigates the feasibility of using natural fibers as cost-effective, environmentally sustainable core materials for vacuum insulation panels (VIPs). First, a comprehensive experimental study was conducted for 10 potential natural fiber candidates. The thermal conductivities of the 10 natural fiber mats at various vacuum pressures were measured; their compression and morphology properties were quantified. In addition, an analytical model was used to explore the major factors that influence the thermal conductivity of natural fibers as a function of internal air pressure. Results show that recycled cotton, kapok, and bamboo fibers are ideal candidates for VIP core materials; at <0.05 Pa, their thermal conductivities varied between 2 and 4 mW/(m∙K). Furthermore, for some fibers, thermal conductivity was inversely proportional to fiber density. For the selection of fiber materials for VIP cores, the ideal fiber candidate has a small fiber diameter and a low fiber mat density. Based on thermal measurements, even though the internal air pressure of 5 Pa was enough to attain the minimum thermal conductivity, obtaining internal air pressure below 5 Pa is recommended for prolonged service life, considering small leaks of VIP package barrier films and potential off-gassing from fibers. The simulation results predicting the effective thermal conductivities matched the experimental results well. These findings indicate that natural fiber–based VIPs have the potential to be a sustainable, inexpensive alternative to the current technologies in building insulation materials.

36 MATERIALS SCIENCE↗

Developing a Composite Vacuum Insulated Panel (VIP) Insulation/Vinyl Siding Composite Technology for Retrofitting Residential Walls

This paper reports on a project that has attempted to seize on an opportunity to take a giant leap forward in commercializing a technology that would address a key opportunity to achieve energy savings in the existing residential housing stock. It is typically very difficult to increase the R-value of the walls in existing residential housing as doing so from the inside is disruptive and there have not been good solutions to increase thermal envelope performance from the exterior through adding continuous insulation due to the additional work required to fit existing architectural features to the new wall thickness and to reclad the façade. A high thermal resistivity or R-value per inch product that can be used in these applications offers an excellent solution.This paper summarizes a three-year research project to a produce vacuum insulated panel (VIP)/vinyl siding that would have sufficient R-value to meet the continuous insulation requirements of the 2018 International Energy Conservation Code (IECC, 2018) in all climate zones and has a much thinner profile that will facilitate its application to existing residential homes without the need for expensive retrimming of the architectural details. The paper will supply information on the development of the technology, its thermal modelling, testing, voice of user sessions to solicit input from architects, designers, manufacturers, contractors, and installers, and a techno-economic analysis to gauge its competitiveness with existing product options.

Desjarlais, Andre Omer↗

Developing a Composite Vacuum Insulated Panel (VIP) Insulation/Vinyl Siding Composite Technology for Retrofitting Residential Walls

This paper reports on a project that has attempted to seize on an opportunity to take a giant leap forward in commercializing a technology that would address a key opportunity to achieve energy savings in the existing residential housing stock. It is typically very difficult to increase the R-value of the walls in existing residential housing as doing so from the inside is disruptive and there have not been good solutions to increase thermal envelope performance from the exterior through adding continuous insulation due to the additional work required to fit existing architectural features to the new wall thickness and to reclad the facade. A high thermal resistivity or R-value per inch product that can be used in these applications offers an excellent solution. This paper summarizes a three-year research project to a produce vacuum insulated panel (VIP)/vinyl siding that would have sufficient R-value to meet the continuous insulation requirements of the 2018 International Energy Conservation Code (IECC, 2018) in all climate zones and has a much thinner profile that will facilitate its application to existing residential homes without the need for expensive retrimming of the architectural details. The paper will supply information on the development of the technology, its thermal modelling, testing, voice of user sessions to solicit input from architects, designers, manufacturers, contractors, and installers, and a techno-economic analysis to gauge its competitiveness with existing product options.

Desjarlais, Andre↗

Silica/Polymer and Silica/Polymer/Fiber Composite Aerogels

Aerogels that consist, variously, of neat silica/polymer alloys and silica/polymer alloy matrices reinforced with fibers have been developed as materials for flexible thermal-insulation blankets. In comparison with prior aerogel blankets, these aerogel blankets are more durable and less dusty. These blankets are also better able to resist and recover from compression . an important advantage in that maintenance of thickness is essential to maintenance of high thermal-insulation performance. These blankets are especially suitable as core materials for vacuum- insulated panels and vacuum-insulated boxes of advanced, nearly seamless design. (Inasmuch as heat leakage at seams is much greater than heat leakage elsewhere through such structures, advanced designs for high insulation performance should provide for minimization of the sizes and numbers of seams.) A silica/polymer aerogel of the present type could be characterized, somewhat more precisely, as consisting of multiply bonded, linear polymer reinforcements within a silica aerogel matrix. Thus far, several different polymethacrylates (PMAs) have been incorporated into aerogel networks to increase resistance to crushing and to improve other mechanical properties while minimally affecting thermal conductivity and density. The polymethacrylate phases are strongly linked into the silica aerogel networks in these materials. Unlike in other organic/inorganic blended aerogels, the inorganic and organic phases are chemically bonded to each other, by both covalent and hydrogen bonds. In the process for making a silica/polymer alloy aerogel, the covalent bonds are introduced by prepolymerization of the methacrylate monomer with trimethoxysilylpropylmethacrylate, which serves as a phase cross-linker in that it contains both organic and inorganic monomer functional groups and hence acts as a connector between the organic and inorganic phases. Hydrogen bonds are formed between the silanol groups of the inorganic phase and the carboxyl groups of the organic phase. The polymerization process has been adapted to create interpenetrating PMA and silica-gel networks from monomers and prevent any phase separations that could otherwise be caused by an overgrowth of either phase. Typically, the resulting PMA/silica aerogel, without or with fiber reinforcement, has a density and a thermal conductivity similar to those of pure silica aerogels. However, the PMA enhances mechanical properties. Specifically, flexural strength at rupture is increased to 102 psi (=0.7 MPa), about 50 times the flexural strength of typical pure silica aerogels. Resistance to compression is also increased: Applied pressure of 17.5 psi (=0.12 MPa) was found to reduce the thicknesses of several composite PMA/silica aerogels by only about 10 percent.

Ou, Danny↗

Nearly Seamless Vacuum-Insulated Boxes

A design concept, and a fabrication process that would implement the design concept, have been proposed for nearly seamless vacuum-insulated boxes that could be the main structural components of a variety of controlled-temperature containers, including common household refrigerators and insulating containers for shipping foods. In a typical case, a vacuum-insulated box would be shaped like a rectangular parallelepiped conventional refrigerator box having five fully closed sides and a hinged door on the sixth side. Although it is possible to construct the five-closed-side portion of the box as an assembly of five unitary vacuum-insulated panels, it is not desirable to do so because the relatively high thermal conductances of the seams between the panels would contribute significant amounts of heat leakage, relative to the leakage through the panels themselves. In contrast, the proposal would make it possible to reduce heat leakage by constructing the five-closed-side portion of the box plus the stationary portion (if any) of the sixth side as a single, seamless unit; the only remaining seam would be the edge seal around the door. The basic cross-sectional configuration of each side of a vacuum-insulated box according to the proposal would be that of a conventional vacuum-insulated panel: a low-density, porous core material filling a partially evacuated space between face sheets. However, neither the face sheets nor the core would be conventional. The face sheets would be opposite sides of a vacuum bag. The core material would be a flexible polymer-modified silica aerogel of the type described in Silica/Polymer and Silica/Polymer/Fiber Composite Aero - gels (MSC-23736) in this issue of NASA Tech Briefs. As noted in that article, the stiffness of this core material against compression is greater than that of prior aerogels. This is an important advantage because it translates to greater retention of thickness and, hence, of insulation performance when pressure is applied across the thickness, in particular, when the space between the face sheets is evacuated, causing the core material to be squeezed between the face sheets by atmospheric pressure. Fabrication of a typical vacuum-insulated box according to the proposal would begin with fabrication of a cross-shaped polymer-modified aerogel blanket. The dimensions of the cross would be chosen so that (1) the central rectangular portion of the cross would form the core for the back of the box and (2) the arms of the cross could be folded 90 from the back plane to form the cores of the adjacent four sides of the box. Optionally, the blanket could include tabs for joining the folded sides of the blanket along mating edges and tabs that could serve as hinges for the door. Vacuum bags in the form of similar five-sided boxes would be made of a suitable polymeric film, one bag to fit the outer core surface, the other to fit the inner core surface. By use of commercially available film-sealing equipment, these box-shaped bags would be seamed together to form a single vacuum bag encasing the box-shaped core. Also, a one-way valve would be sealed to the bag. Through this valve, the interior of the bag would be evacuated to a pressure between 1 and 10 torr (approximately between 0.13 and 1.3 kPa). The polymer-modified aerogel core material is known to perform well as a thermal insulator in such a partial vacuum.

Stepanian, Christopher J.↗

Transformative Efficiency and Automation in Modular Homes (TEAMH)

This report documents the Transformative Efficiency and Automation in Modular Homes (TEAMH) project, which evaluates the integration of advanced building envelope technologies and automation-assisted modular construction to improve residential energy performance and construction efficiency. The study investigates high-performance insulation systems, including vacuum insulation panels (VIPs), combined with light gauge steel (LGS) modular construction and factory automation. Laboratory testing, whole-building energy modeling across multiple climate zones, and factory demonstrations were conducted to assess thermal performance, energy savings, and production efficiency. Results indicate that upgraded envelope assemblies can achieve up to ~50% heating and ~34% cooling energy savings relative to IECC 2018 code-compliant homes, while automation-assisted construction can reduce wall assembly time by 24%–46% compared to conventional wood framing. The findings demonstrate the potential for scalable, high-performance modular homes that deliver significant energy savings with competitive projected costs.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Inexpensive and durable aerogel-based VIP cores

The goal of this project was development of low-cost aerogels to be used as cores of Vacuum Insulated Panels (VIP). The specific aims were: 1. Aerogels to be based on phenolic chemistry to minimize flammability. 2. Aerogels to be in monolithic form and to have mechanical properties sufficient to allow their use as cores of VIPs without collapsing after evacuation. 3. Aerogels to have a cost per kg lower than the cost of fumed silica, one of the most common VIP cores. The achievements are: 1. Phenolic aerogels have been fabricated in monolithic form with thermal conductivity of 0.023 W/m·K, density ~ 0.25 g/cm 3 and a modulus of compression > 10 MPa. The aerogels can withstand the stresses of VIP evacuation without any appreciable deformation. 2. Drying of aerogels was carried in the initial stages of the project via sublimation of frozen solvents, following the procedure described in M. F. Bertino and T. Selden, “Fabrication of Aerogels and Aerogel Composites by Ambient Pressure Sublimation of Frozen Solvents”, PCT/US20/39485. Monoliths as large as 30 x 30 x 2 cm can be fabricated with the proprietary ambient fabrication technique which are free of cracks and warping. 3. Cost analysis was carried out and refined multiple times, cost drivers were identified, and the fabrication procedure was streamlined. Our cost model yields an aerogel cost of $\$$5.78/kg, which compares well with the price of fumed silica ($\$$6.2/kg FOB New York as of March 2023). 4. The monoliths can be cut into custom shapes and used as VIP cores. Cores fabricated with our technique have a thermal conductivity λ = 0.011 W/m·K at a pressure >10 mbar. 5. A variant of the technology yielded fireproof materials, described in M. F. Bertino, T. Moon, G. Waller, J. Ko and D. Clifford, “Fireproof thermal insulation”, Provisional Patent Application 63/415,386. 6. A spin-off company was created (ThermaGel Innovations, Inc.) which licensed technologies developed under this award. PI Bertino is a board member of the newco which is now raising capital to build a pilot plant.

36 MATERIALS SCIENCE↗

Inexpensive Superinsulation for Cryogenic and Highly Insulating Applications (CRADA Final Report)

This effort will use our novel insulation formed into effective “solid” (as compared to powder) insulating panels and/or wraps to demonstrate important technical achievements including scaling appropriate crosslinking to directly and cost effectively address vacuum insulated panel (VIP) applications and cryogenic component wrapping to help reduce energy use. This project will improve and scale-up processes (from 3” diameter disks) to make larger samples (e.g., 12” x 12” x 1”) Wow, cfor external evaluation and testing.

36 MATERIALS SCIENCE↗

Durability of ABC Team Wall Assemblies

This study evaluates the long-term hygrothermal durability of four advanced retrofit wall systems using a field test facility located in Hollywood, South Carolina, representative of a mixed-humid coastal climate (Zone 3). The research focuses on assessing the thermal and moisture performance of a baseline wall assembly retrofitted with (1) Tremco/Dryvit prefabricated panel systems (Revitalite and Fedderlite), (2) Reinforced Fiberglass Plastic (RFP) panels developed by Oak Ridge National Laboratory (ORNL), and (3) Vacuum Insulated Panels (VIP) integrated with EPS by Home Innovation Research Labs (HIRL) and ORNL. A baseline wall representing a typical uninsulated wood-frame construction was used for comparison.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗