Download "user manual"

Mandatory Provisions HVAC
Example 6-M—Data Processing Rooms
Q
An office housing both workers and data processing equipment is cooled by HVAC
equipment that is provided primarily to maintain space conditions for the data
processing equipment. Does the equipment have to comply with the Standard or is it
exempt because its purpose is primarily to cool process equipment?
A
Determining whether a system is serving a process role or comfort conditioning role can
be complicated when the space is occupied by both workers and process equipment. In
general, if the HVAC system is no different than it would be for comfort applications,
then it must comply with the Standard. However, if the equipment includes special
humidification and dehumidification systems designed to maintain tight humidity and
temperature control not normally required for comfort applications, then it is considered
a process application and need not comply with the Standard.
User’s Manual for ANSI/ASHRAE/IESNA Standard 90.1-2007
Copyright ASHRAE
Provided by IHS under license with ASHRAE
No reproduction or networking permitted without license from IHS
Licensee=AECOM/5906698001, User=li, xiaoxiao
Not for Resale, 07/02/2009 03:02:18 MDT
6-19
--`,``,``,`,,,,,`````,`,```,```,-`-`,,`,,`,`,,`---
walls are considered to have different
orientations if the directions they face
differ by more than 45 degrees. For
example, in Figure 6-C, a zone must be
provided for each of the exposures that
exceed 50 feet in length, while the shorter
exposures on the serrated side of the
building need not have individual zones.
These shorter exposures may be served by
adjacent zones serving other exposures.
▪ Each perimeter system zone is
controlled by one or more thermostats
located in the zones served. In the past,
perimeter systems were often controlled
by outdoor air sensors that would reset the
output of the system proportional to
outdoor air temperature. But since solar
loads can offset some of the heat loss
from a space, this type of control
inevitably causes overheating by the
perimeter system when the sun is shining
and subsequent fighting with the cooling
system. Even when this control is
improved by solar compensation, it still
can result in wasteful fighting between
interior and perimeter systems due to
varying internal loads. Therefore, only
controls that respond to temperature
within the zones served are allowed.