Date of Submission

4-2023

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering

Department

Civil and Environmental Engineering

Advisor

Byungik Chang, Ph.D., P.E., M.B.A

Committee Member

Hyungjoo (Jay) Choi, Ph.D., P.E

Committee Member

Goli Nossoni, Ph.D.

Keywords

PV Panels and CMU Blocks, Sustainability, Long Term Deflection, Exposure Class, Risk Category, FE Modeling

LCSH

Building-integrated photovoltaic systems, Maintainability (Engineering), Sustainable engineering, Finite element method, City planning--New York (State)--New York

Abstract

Concrete Masonry Unit (CMU) blocks (Ballasts) to counterbalance an uplift wind pressure on Photovoltaic (PV) panels have been used widely. In contrast to mechanically attaching PV panels through penetration of a roof slab, the use of CMU blocks is preferred by many building owners, as penetrating and attaching the panels to a roof slab will pose a serious threat to the warranty of roof membranes, which typically last for 30 years. On the other hand, placing CMU blocks along with PV panels and other system components on a rooftop slab adds additional dead load, which may raise a concern regarding the long-term serviceability of the rooftop slab.

This study is mainly focused on the uplift wind calculation to determine the optimal number of required ballasts, roof slab serviceability analysis to determine sustainability in the form of long-term deflections, and a feasibility study on the economic benefits of PV installation. A building with ballasted PV which has typical material and section properties located in New York City was selected and analyzed.

The initial pre-PV long term deflection was found to be 0.83 in. and 1.05 in. for roof live loads of 60 psf and 100 psf, respectively, while the allowable deflection limit for the given slab geometry is found to be 1.15 in.in accordance with the local code design requirements. Both live load conditions were applied along with self-weight and other dead loads to calculate the initial long-term deflection. The long-term deflection results from post-PV serviceability analysis were found to be below the pre-PV deflection. Hence, it is concluded that installing PV systems on a rooftop slab does not have a significant effect on its service life.

Economic feasibility analysis is also conducted by using project profitability indicating parameters. Simple Payback Period, Net Present Value, Discounted Cash Flow, Internal Rate of Return, Simple Cash Flow, and Profitability Index were found to be 5 years, $165,173, $135,486, 18%, and $402,772, respectively. This confirms that installing PV systems on rooftop slabs of existing buildings in New York City is an attractive investment.

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