Transparent Wood Composites for Energy Efficiency Applications

Energy used for lighting and thermal comfort contributes to more than 50% of the total energy consumption in residential and commercial buildings. Consequently, conserving air conditioning and lighting usage especially during daytime can yield substantial savings. Effective and consistent sunlight harvesting can substantially reduce electrical usage while promoting natural and comfortable indoor lighting. Meanwhile, effective thermal insulation of the building material could ultimately pay for itself through cost savings in air conditioning usage. Windows play a key role in energy management within buildings. Glass is the most commonly used material for sunlight harvesting. However, a glass window has very LOW energy efficiency due to mainly two reasons: 1. Glass often creates shadowing effects and discomfort glare which would require daytime lighting to meet the occupants' needs; 2. One-third of the energy used to heat or cool the building is lost through inefficient glass windows due to the intrinsic high thermal conductivity of glass. Glass also has presented significant safety concerns when used as a building block for residential and commercial structures.In early 2016, Dr. Hu's group at the University of Maryland College Park invented transparent wood. The work was published in a prestigious journal, Advanced Materials. This technology was patented and then reported by the New York Times and CNN, among many other media outlets. Similar to glass, the transparent wood developed by Dr. Hu's group has a high optical transmittance, up to 92%. When evaluated for energy efficiency building applications, the transparent wood developed by Dr. Hu's group has the following advantages compared to glass:(1) Better energy efficiency: The transparent wood composite has much better thermal insulation than glass, which will help better thermal insulate the house and automobiles. The transparent wood can maintain the temperature inside a house (i.e. keep a house cool in the summer and warm in the winter due to lower thermal leakage).(2) Guide Sunlight: The transparent wood as the building material can efficiently guide sunlight to provide consistent and uniform indoor lighting without glare effect in buildings.(3) Anti-shatter: The transparent wood has better mechanical durability and toughness. While the glass shattered immediately into pointy pieces upon mechanical shock, transparent wood stays intact, which is highly desirable as a safe, hassle-free, and anti-shatter, transparent building material. (4) Lighter: Transparent wood is much lighter which is better for safety and installations.(5) Environmental friendly: According to the Clean Air Council, a nonprofit environmental organization, in 2008, only 23.1 percent of glass discarded was recycled. Now, with landfills across the planet, glass is fast becoming a major ingredient in pockets of Earth's crust and it will not decompose any time soon. On the other hand, transparent wood can be made bio-degradable which will substantially reduce the landfill of deserted windows and glassware.In Phase I of the USDA SBIR, we will investigate transparent wood for energy efficiency applications, especially for energy efficiency buildings. Specifically, we will study:scalability of fabrication processes toward transparent wood, especially lignin removal and polymer infiltration;the performance of transparent wood, especially its optical and thermal properties and its environmental stability;potential industrial applications of transparent wood through close collaboration and evaluation.In the eight-month Phase I project, we will focus on evaluating the feasibility of transparent wood for the value-added product especially for energy efficiency related applications. The success of Phase I will increase the technological readiness level for Phase II funding. The Phase II project will focus on the large-scale fabrication of transparent wood for commercialization with a competiti