Page 175 - TCDB combined Book

Chapter 3 DESIGN 151

Building Design:

HVAC Design Calculations (Ventilation)

Ventilation

There are many variables in calculating Ventilation requirements. The method described here and
the chart below is based on air volume calculations that should result in a reasonably accurate
level of ventilation load for pricing purposes. Some ventilation systems will require pre-heating of
outside supply air through use of a make up air handling unit with a heating coil. Calculating the
size (cfm) of make up air units (MUA) and heating coils (Btu) can be determined from your air
volume calculations. Projects requiring various ventilation systems will require interface controls
allowing for possible air handling conflicts. All system and design calculations should be
completed or reviewed by an experienced design professional prior to finalizing your proposal
pricing or preparation of actual working drawings.

Where: V = volume of space to be ventilated in cubic feet
C = number of air changes per hour
M = one hour unit in minutes
CFM = ventilation required in cubic feet per minute

Therefore:

V x C = CFM
M

VENTILATION CALCULATIONS

Installation
LOCATION L/G V x C / M = CFM wall roof MUA

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Legend: L/G - local or general MUA - make up air