# Calculation funtionality

Hi there!

In my CO2 calculator for hotels I need a new functionality that I don’t know how to develop.

There are materials that are purchased only once and last for several years. Therefore, every year a percentage has to be amortized until it reaches 0. For example, if a chair emits 100 kg CO2 and each year it loses 10%, the second year it will have a CO2 equivalence of 90kg CO2.

The problem is that I don’t know how the system calculates the emission in case there is a depreciation and a new item is added. That is, if we have a chair that emits 100 kg and in the second we buy another chair (so 2 chairs in the hotel in total), the total emission would not be 90 kg, but 190.

Would anyone know how to do it?

Thanks !

Question isn’t clear but youd have a different dataset for every item and calculate the amortization of each item separately and the total emission is the emission per dataset and you sum all the totals.

Thanks for the answer. I already have that. What I don’t know how to make bubble calculate the amortization (i.e. CO2 emissions - 10%) + (CO2 emissions) if the figure I enter is higher than the one entered the previous year.