Willemsen, Peter - U. Minnesota
The objective of this proposal is to increase knowledge for how environment and urban form interact. Its hypothesis is that optimal urban structures and layouts exist which can minimize energy use while also minimizing air pollution exposure.
An extremely fast and inexpensive energy use and dispersion modeling tool for urban areas will be developed by building on PIs? previous work. The modeling system will utilize the unique computational parallelism afforded by graphics processing units (GPUs, that are regularly utilized in the video game industry), to run many simulations in an effort to train an optimization algorithm for determining optimal designs for urban structures and their layout. This proposed research will also utilize an interactive and immersive virtual environment to provide better understanding and refinement of the complex physical processes associated with the energy balance and pollutant dispersion in an urban setting.
Modeling capabilities that will be developed through this work will aid urban planners in developing useful and novel planning strategies to improve the sustainability of modern cities. The PIs will work with urban planners throughout the model development process. These modeling capabilities will also aid architects by providing them with a tool that not only analyzes isolated buildings, but also provides understanding regarding the interaction of multiple buildings during the design process. In addition, this proposal has a substantial outreach component designed to provide a unique educational opportunity for American Indians, Alaskan Natives, and other minorities to learn about various aspects of modeling in environmental engineering. Through our program, American Indian students from Northern Minnesota will be invited to a weeklong interactive learning symposium during each of the three years of the grant.
Intellectual Merit In recent years, urban planners have attempted to make cities more sustainable by espousing higher density urban design concepts such as Compact Cities, Walkable Communities, and New Urbanist Developments. It has been argued by some urban planners that the per capita energy use and air pollution emissions in densely built cities are less than in their more sprawling less dense counterparts. However, as urban density increases, the ability for pollutants to be transported out of the urban area is inhibited. This complex interaction between various types of urban form, energy use and air quality must be better understood in order to improve the sustainability of cities. This project has addressed the critical need to increase knowledge regarding how the environment and urban form interact. Specifically, we have produced new computer software tools with the capability of quantitatively evaluating the energy efficiency and pollutant dispersion efficiency of large city layouts. Our tools can be used answer city specific questions such as: Where should a new building be placed among surrounding buildings? Would it be better to have a wide and low building or a tall and narrow building? What are the effects of highly reflective windows on the neighboring building’s air conditioning and lighting costs? Will a particular building configuration be more susceptible to trapping street level pollutants? Since problems such as Urban Heat Islands are the result of the interaction of many buildings, mitigation techniques must take into account the impacts of individual buildings as well as the interaction amongst buildings. The computation tools or software that have been developed as part of this project include a complete city urban energy use model (QUIC Energy - http://envsim.d.umn.edu/) and pollutant dispersion model (GPU Plume - www.d.umn.edu/~willemsn/gpuPlume/). This tool allows a user to very building materials, site-specific meteorological conditions and urban layouts to compute temperatures and fluxes of heat throughout the city. The tools that we have developed through this project, and continue to develop, require the investigation of many scenarios and simulation of physics that include heat transfer and fluid mechanics. To help produce the answers to the types of questions described above, we have taken advantage of the computational parallelism afforded by graphics processing units (GPUs, that are regularly utilized in the video game industry). This technology enables us to run urban environmental simulations much faster than previously possible, so that many different urban configurations can be tested. However, most realistic urban design scenarios contain too many choices to select from in a reasonable amount of time. Hence, we have adapted a suite optimization schemes to help select the best urban configuration or family of configurations including stochastic optimization techniques such as simulated annealing (SA) and genetic algorithms. Broader Impacts A very important broader impact of this project has been the multi-disciplinary graduate student training that it has provided to students at the University of Utah and the University of Minnesota, Duluth. This project has produced masters and PhD students with capabilities to solve problems at the interface of engineering, meteorology and computer science Our project has also had an important academic outreach component. Each year of the project, our team provided unique hands-on educational opportunities for American Indians, Alaskan Natives, and other minorities to learn about various aspects of computer modeling in environmental engineering. First year college students conducted design projects at the University of Minnesota Duluth using our research tools to better understand the transport of pollutants in regions that were locally relevant to the students. Students were extremely creative with these open-ended projects and expressed great interest in the design projects. These students worked directly with the lead professors from the project, learning from and testing the research tools being developed, such as our interactive and immersive virtual urban dispersion environment (see Virtual Reality Demonstration image), GPU Plume, and QUIC Energy. Finally, we have worked with urban planners throughout the project to obtain feedback and share our modeling ideas so that our tools will be of greatest benefit to those who can use them to make decisions.
