The built environment currently consumes 51 percent of total U.S. energy, of which 39 percent is consumed by the operation of buildings (primarily in heating and cooling) and 12 percent is consumed by construction material fabrication and demolition.
The built environment also contributes to 55 percent of total U.S. CO2 output, of which 43 pecent is the result of energy production for building operation and 12 percent is again in material fabrication and demolition. At Stanford, research on innovative, sustainable building materials is one of the ways we are seeking to lessen the negative impact of the built environment on our natural environment.
We are developing new construction materials, and re-engineering current materials, that are cement-based, polymer-based and bio-based. Our research is cross-disciplinary with collaborations among civil, environmental, chemical and material science engineers. Current materials research in our department includes the development and evaluation of fiber-reinforced polymeric materials that are made from renewable resources such as biobased polymers and natural plant fibers. Advantages of such materials include a reduced dependence on nonrenewable energy sources for materials production and a reduction of recalcitrant, non-degrading construction and demolition debris in landfills.
The ability of these materials to replace various non-structural and structural materials in buildings, to avoid deterioration while in service and to biodegrade after their useful service life is currently being investigated. Computational models and theoretical developments are underway to predict the performance of these highly nonlinear materials. In the area of improved building energy-efficiency in building operations, we are investigating new green insulating materials in structural panels.
Additional research is exploring re-engineering existing materials for improved performance and sustainability, including the application of fiber-reinforced polymer composites and high-performance fiber-reinforced cement-based composites, such as Engineered Cementitious Composites (ECC) that exhibit very fine, multiple cracking and tensile strain hardening up to strains of 3 percent. These materials, commonly called “bendable concrete” in the mainstream media, are highly damage-tolerant in both tension and compression and have potential for improved durability against corrosion as well as resistance to overloads such as earthquakes with minimal damage.
The application of these materials to new, sustainable building and infrastructure designs, as well as to structures needing seismic retrofit, is being investigated through physical experiments and computer modeling, including performance-based assessments.