Date of Award


Document Type


Degree Name

Master of Science (MS)


Mechanical and Civil Engineering

First Advisor

Hamidreza Najafi

Second Advisor

Hamid Hefazi

Third Advisor

Troy Nguyen


The present work focusses on investigating the thermal performance of different energy efficient roof systems for buildings for different climates. Buildings constitutes about 40 percent of total energy consumed by United States, and previous research shows that 20 percent of the building cooling load comes through ceiling of a building. Thus, it is important to analyze different energy efficient roof systems which can help in reducing building cooling and heating load. The present study focusses on three technologies – green roof, radiant barriers and photovoltaics. To analyze the performance of these systems, a detailed energy based mathematical model were developed in MATLAB. The results were first validated with experimental data obtained from previous research. A set of simulations were conducted to calculate the different system’s performance for a building for six different cities with different climates – hot and dry, hot and humid, cold, marine, mixed humid and subarctic. To investigate the performance of these systems further, an energy saving analysis was conducted associated with the temperature variation. The energy savings associated with radiant barrier was found to be highest than the savings associated with green roof and photovoltaic system for each climate. However, in terms of environmental impact green roof provides more benefits. The savings of photovoltaic system is lowest, but it contributes to the generation of electricity which in turn can help in reducing building load on the grid. A mathematical model for cost saving analysis was also developed and the benefits of these systems over conventional roof systems were discussed in detail. The results associated with energy savings analysis for these systems were compared to better understand their advantages and disadvantages over each other. It can be concluded that each system has its own advantages and disadvantages but all of them were able to reduce building load.