The Effect of Urban Density on Building HVAC Performance
Open Access
- Author:
- Gracik, Stefan M
- Graduate Program:
- Mechanical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 26, 2014
- Committee Members:
- Dr Jelena Srebric, Thesis Advisor/Co-Advisor
- Keywords:
- urban
density
cfd
openfoam
energyplus
energy efficiency
hvac
outdoor cfd
urban heat island - Abstract:
- The world is undergoing fast urbanization, and recently over fifty percent of the world’s population is reported to live in urban areas. Urban areas bring denser living conditions for both people and buildings. Growing global energy use has brought interest in the study of energy use in these rapidly growing urban areas. Common building materials absorb sunlight at a much higher rate than naturally occurring ecology. On the large scale, this results in the urban heat island effect, which refers to the higher temperatures present in dense urban areas compared to surrounding rural and suburban regions. The coefficient of performance of some common building HVAC systems is highly sensitive to local outdoor temperatures. Quantification of the degradation of COP in dense urban areas due to local temperatures is an important area of study as the world’s population continues to urbanize. The goal of this master’s thesis is to use computational fluid dynamics modeling combined with building energy/thermal modeling to predict local temperatures in urban environments consisting of both low dense suburban/rural regions and dense city centers. Open source software packages OpenFOAM and EnergyPlus are used in tandem to calculate local air temperatures. The study offers insight on the use of these packages for calculating urban thermal environments. The ability of the software to predict local temperatures in urban environments is validated by comparing simulation results to temperatures collected in an actual urban environment. Following this validation, the same procedure is used to estimate local air temperatures in uniform neighborhoods of varying density. The findings indicate that rooftop air conditioners in urban areas can have a reduction in COP of up to twenty percent, compared to a corresponding rural area. Window air conditioners can have reductions in COP of over twelve percent, depending on placement.