TARGET LEVEL ASSESSMENT

This task consists of defining target levels for indoor and outdoor conditions based on requirements for laws and regulations, human health, production processes and equipment, and type of premises and construction. Target lev­els should also be defined for the ventilation system. For the decision tree, see Fig. 3.6.

Target levels are needed as a standard to which system solutions are com­pared. During comparison it may become evident that target levels cannot be achieved with any solution or that they lead to very expensive solutions. In such cases target levels have to be reconsidered (back coupling).

Explanations of Fig. 3.6 Step I: Musts

Clarify requirements due to laws, regulations, standards related to legisla­tion, processes, and equipment.

Connections • process • pipes • ducts • electricity • emissions • etc.	‘ Windows ‘ Doors ‘ Cranes ‘ etc.

FIGURE 3.4 Process description. Division of process into such parts that their inputs, oucputs, and target levels can be specified. A subprocess can be source or separate area/room that is to be protected from its environment.

Step 2: Needs

Clarify standards not related to legislation, such as those related to human comfort, guidelines, codes of practice, and custom needs.

Step 3: Target Levels

Decide target levels based on musts and needs.

Process layout Structures and building envelope

Building Layout

Openings

1 Height > Width

• Length

1 Point of compass

» Number of floors

1 Partitioning

1 Zoning

1 Space for ventilation equipment

• Main structures

• Structures needed for ventilation equipment

• Massiveness

• Tightness

• Thermal conductivity

• Louvers

• Windows

• Doors

• Radiation transmissivity

• Shading

• Thermal conductivity

Return from		Return from
Detailed design		Detailed design

FIGURE 3.5 Building layout and structures.

Step 4: Design Conditions

Suggest and agree with customer on the outdoor conditions within which the target levels have to be met, e. g., absolute maximum temperature versus 95% temperature.

Step 5: Reliability

• Study the reliability requirements of the process with the customer.

• Define and get the customer’s acceptance of the needs for ventilation system reliability, e. g., what is the allowed break-off time.

The tools for this task include:

• Laws, regulations

• Standards

• Guidelines, codes of practice

Musts: Regulations, etc.

Return from Calculation of Total Building Loads

Return from Local Protection

Needs: Human comfort, etc. Target Levels • Temperature • Humidity • Air velocity • Impurities • Exposure time

Exhaust > Environmental regulations ’ Content of contaminant ’ Total amount of contaminant

Main zone

Local zones

! 1 1 1 ) 1

Ventilation

System

• Energy consumption

• Reliability

• Investment /

Life cycle costs

Equipment

• Efficiency

Design Conditions

Reliability

FIGURE 3.6 Target level assessment.

Posted in INDUSTRIAL VENTILATION DESIGN GUIDEBOOK