hi,
Data centre's are energy beast's,
from past experience, operating costs
in the end will probably drive the end
user to increase the db temp. to try
and save energy.
Data centres that were orginially
designed (as mentioned by ercanbaser) for
21 deg C, 50% - and were subsquently modified
with the approval of the data equipment
manufacturer, for 26 deg C db - saving millions
of dollars per year.
Don't forget that ashrae guide is not engraved
in stone, there are only guidelines. Choose
your conditions carefully to suit your
application.
In your case it may not be possible to
adopt a higher design, engineering is
a creative endeavour, don't let fixed
ashrae guideline dictate your design.
at the end of the day the owner will
thank you.
cheers,