Investment Calulation

Investment calculation for chemical plants, waste water technology and food industry technology means:

 

Genauigkeit vs. Aufwand

This diagram shows the known state only:
the better the desired accuracy of cost calculation - the bigger the expenses.

fastest: the estimate of coarse expenditures (ca. +- 40%)

mostly sufficient: calculation by comparison and/or calculation by the method of factor-addition (ca. +-10%)

most exact: the detailed calculation (ca. +-5%)

Estimate of coarse expenditure:
This method of calculation is fast and easy: (Costs of machinery, apparatus and vessels) x (factor depending on type of plant) = investment costs. The costs of the complete equipment will be estimated or investigated by inquiries at the manufactures. The type-factor usually goes from 2 to 5 and depends on the type of plant.i.e. plants for solid handling, liquid handling or ex-plants with intensive process instrumentation. The method does not give very accurate results; but usually one can anwser questions like 'Does this process/plant have any chance to be realised'.

Method of comparison:
one compares an already realised plant A with the plant B (same type of plant) to be realised :
The uncertainity of the calculation is overcome by addition of 10% to the total. 

Method of factor-addition
The costs of equipment are calculated by inquiry or with sufficient experience by estimate. The project cost  is the sum of the costs for equipment plus the work-specific additions. The uncertainity of the calculation is overcome by addition of 10% to the total. 

Detail calculation:
All costs of the equipment (at ground moving work by appropiate calculations) and all specific work are calulated by inquiry. Additional costs (i.g. for authorities, legal permits, etc.) are listed separately and added. Expenses for this method of calculation is relatively high and it typically also needs considerable time. The accuracy normaly is about +-5%.