NDJ Sustainable
Engineering,  LLC


We are working toward net-zero energy buildings through harvesting solar energy and improving energy efficiency of building envelope!

Building Integrated Photovoltaic Thermal System (BIPVT)

We are conducting intensive research and development to validate the manufacturing and integration method.


    In manufacturing fiber reinforced lightweight concrete, the proposed technology requires a method to produce foam from commingled plastic waste (CPW), complicated by the variability of plastic waste stream compositions. There exist two basic types of blowing agents to produce polymeric foams. Chemical blowing agents undergo a chemical reaction to produce a gas that causes foaming. Physical blowing agents are typically gases such as carbon dioxide or nitrogen that are introduced at elevated pressure and expand when the pressure is reduced. Both methods can be employed to foam most polymers and their applicability to blowing CPW foams will be investigated in the proposed research. This involves several steps: first determining conditions by which CPW can be foamed with supercritical carbon dioxide and ADC, granulating the foam, mixing foam particles with the other concrete ingredients, and finally determining how particle size and content influence concrete properties, such as compressive strength, density, thermal conductivity and sound transmission.

    As for fiber reinforcement, numerous types of fibers are widely used worldwide. In addition to the obvious choices of steel, AR-glass, polypropylene and other fibers, we propose to evaluate the suitability of natural fibers such as sisal - the ultimate in terms of sustainable construction materials because of their near-zero embedded energy and ability to regenerate, sequestering carbon dioxide in the process.

    Our recent study of FRLWC has achieved a number of specifications: 1) ultra-lightweight (of the order of 60 lbs/ft3); 2) superb thermal insulation; 3) large sound absorption capacity over a large portion of the audible spectrum; 4) sufficient mechanical strength to safely carry all external loads; 5) adequate durability, i.e. the material's ability to maintain all properties through the building's service life; 6) large-scale utilization of expanded polystyrene, a hard-to-recycle major component of the solid waste stream; 7) fiber reinforcement to assure adequate ductility, fracture toughness and energy absorption capacity. We will investigate appropriate manufacturing method to make the FRLWC ready for the proposed solar panel. The end product, a material that satisfies all performance specifications, and the manufacture rate of which should be of the same order of magnitude as regular concrete, will serve as an ideal platform for the systems and components described herein.

    For FGM manufacturing, we use suspension liquid to create the graded microstructure of the mixture. Aluminum (Al) and high density polyethylene (HDPE) are mixed to fabricate FGM layers in the laboratory. Al powder and HDPE powder are thoroughly mixed with ethanol. Because Al and HDPE have significantly different specific gravities (2.7 and 0.95, respectively) over a range of size distribution (50-150 micrometer and 5-30 micrometer, respectively), the two types of powders will fall down at different velocities and thus create a graded microstructure. This process can be expedited by vibration of the mix. When a desired graded microstructure forms, the ethanol is filtered out for reuse. By heating up the graded powder mix in a vacuum oven and curing it, we can obtain the solid FGM layer. NDJ does not manufacture photovoltaic or thermoelectric cells, which will be acquired from other partners for system integration.

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