.. _refrofit-benefit-cost-intro:

Refrofit Benefit-Cost Ratio
===========================

This calculator represents a decision-support tool for deciding whether the employment of retrofitting measures to a 
collection of existing buildings is advantageous from an economical point of view. For this assessment, the expected 
losses considering the original and retrofitted configuration of the buildings are estimated, and the economic benefit 
due to the better seismic design is divided by the retrofitting cost, leading to the benefit/cost ratio. These loss 
curves are computed using the previously described Classical PSHA-based Risk calculator. The output of this calculator 
is a benefit/cost ratio for each asset, in which a ratio above one indicates that employing a retrofitting intervention 
is economically viable.

In :ref:`the figure below <retrofit-benefit-cost-calc>`, the input/output structure for this calculator is depicted.

.. _retrofit-benefit-cost-calc:
.. figure:: _images/io-structure-benefit-cost.png

   Retrofitting Benefit/Cost Ratio Calculator input/output structure.

For further information regarding the theoretical background of the methodologies used for each calculator, users are 
referred to the :ref:`underlying science <underlying-science>` section of the documentation.