Cost/benefit analysis for building core sunlighting systems

The economic efficiency of building core sunlighting systems (BCSS) that are used to deliver sunlight into building core is essential for their widespread use. This study analyses the costs and benefits of using the BCSS through a parametric evaluation process considering key parameters, such as installed and saved lighting power, electricity costs, BCSS initial costs and cleaning costs. The latest seems to be a very influential parameter. Values higher than $2/m(2) are not expected to result in a positive return of investment in the installation of the BCSS. Economic performance matrices have been generated to provide parametric tools, by which the economic performance conditions can be easily estimated. They show a wide spectrum of scenarios includes best-case and worst-case scenarios. In the worst-case, the BCSS cannot payback the investment. Meanwhile, in the best-case, a payback period of about 4 years is achieved, which is equivalent to about 81% saving of the electric lighting system electricity costs throughout the BCSS lifespan. This can be translated into $0.56 savings for each kWh of installed electricity power throughout the BCSS lifespan. (C) 2016 Elsevier B.V. All rights reserved.