<< Click to Display Table of Contents >> Navigation:  Wadiso 6 User Guide > Tank Cost Optimization to be included in future Wadiso version > Additional Wadiso Tank Sizing Data Definition > Consumption Characteristics

In order for the program to calculate the required balancing capacities of tanks with the critical period technique, it has to be supplied with information as to how the consumption in the system fluctuates around the average water demand. More specifically, it requires the following information:

i) The (annual) average demand rate in the system (in l/s or USgpm).

ii) The distribution of consumption among the nodes in the system, i.e. the percentage of the total demand in the system that is consumed at a specific node.

iii) The peak day factor, i.e. the average demand rate on the peak day expressed as a ratio of the (annual) average demand rate.

iv) The peak week factor.

v) The 24-hour demand pattern in the system, with each hour in the day expressed as a ratio of the average demand for the day.

The distribution of consumption (i.e. the percentage of the total demand that is consumed at a specific node) is calculated internally by the program, and is based on Load Case # 1 as specified in the optimization data. The other consumption information has to be entered by the user in the Tank Sizing Parameters Editor, and is described below.

•ANNUAL AVERAGE DAILY DEMAND : The user should provide the annual average demand rate for the entire system, e.g. in l/s or gpm.

•PEAK-DAY: This is the peak day factor, or in other words the average demand rate on the peak day expressed as a ratio of the annual average demand rate. By definition, this value has to be equal to or larger than 1,0. In most systems this value is in the range 1,5 to 3,0.

•PEAK-WEEK: This is the peak week factor, or in other words the average demand rate during the peak week (7-day period) expressed as a ratio of the annual average demand rate. By definition, this value has to be equal to or smaller than the peak day factor, and equal to or larger than 1,0. If no value is entered for the peak week factor, the program calculates a default value, based on the peak day factor, as follows:

Peak Week Factor = 0,5 x (Peak Day Factor - 1) + 1

•24-HOUR DEMAND PATTERN: The user has to enter the 24 fractions, which describe the pattern of water use over a 24-hour period. Each hour in the day is expressed as a fraction (ratio) of the average for the given day. The Demand Fluctuation Graphs show an example of such a 24-hour demand pattern. By definition, the average of the 24 values entered must equal 1, or in other words the sum of the 24 values must equal 24. It is therefore set as a precondition in the program that the 24 values entered must add up to a total of 24. If this is not the case, an error message will appear.