# SELECTION OF SYSTEM

There are two different tasks in system selection: acceptance of systems based on target levels, and comparison of acceptable systems in order to choose the most desirable one.

Based on technical calculations the conditions achievable by different sys­tems (ventilation, cleaning, etc.) are compared to target levels to identify ac­ceptable systems. Dimensioning properties could be:

• Mass and heat balances

• Room flow models

Acceptable systems are compared to each other and the most suitable system is selected on the basis of different parameters, such as power and energy con­sumption and investment and life cycle costs. See Fig. 3.12. Tools for compar­ison are energy balances and cost analyses.

Explanations of Fig. 3.12

Step I: Alternative Ventilation/AC Systems

Select alternative ventilation systems for comparison.

Step 2: Alternative Air Distribution Systems

Select alternative air-distribution systems for comparison.

Step 3: Technical Calculations

Calculate the operation of different solutions.

Step 4: Comparison to Target Levels

• Compare conditions reached with different systems to target levels. Alternative Air Distribution Systems

 Alternative Air Distribution Systems

 Reconsider System with Available Equipment

 Technical Calculations

‘ Heat/energy balance ‘ Contaminant balances Comparison to Target Levels

 Design of Design of Control Control Strategy Strategy

 Sl. l SN.2 Acceptable solutions:

Comparison Calculation of Acceptable Systems

• Power/energy consumption

• Heat recovery

• Costs: • Investments

• Life cycle

Selected System

FIGURE 3.12 Selection of system.

Accept systems that fulfill the targets for further comparison.

If no acceptable system exists, return to calculation of Total Loads to consider whether there is something that can be done with the total loads.

Step 5; Design of Control Strategy

• Design control strategy for acceptable systems in order to handle different situations (seasonal, process variations).

• As in step 4, if none of the acceptable systems can handle different situations, return to calculation of Total Loads to consider whether there is something that can be done with the total loads.

Step 6: Comparison Calculation of Acceptable Systems

Calculate costs, consumption of goods (energy, electricity, etc.), and possi­ble heat recovery of acceptable systems.

Step 7: Selected System

Select the optimal system based on the comparison calculations.

The tools include:

• Zone models

• CFD

• Energy simulation