. A/C...
    . Expandable / scalable:  well planned, but not all deployed on day 1.
    . "Globally minimal and locally maximal"; flexible, forward-thinking
        (e.g., overhead ducts, overhead booster units, on-rack booster units,
        in-rack air movement units, etc.)
    . Plan for water chiller loops
       . Careful placement of first-day CRAC units
       . Drains, etc.
       . Adequate floor height...
    . Plenty of under-floor space needed:  >18 inches
    . Cable trays just under the floor provide minimal constriction to air flow.
    . Vapor barrier walls and ceiling
    . Ceiling MUST include flexibility for things like re-routable return-air
       ducting with in-duct air "fans", coupling to A/C intake plenum, etc.
    . Plan component (CRAC, etc.) placement for the entire space, including
       eventual power panel replacement.

 . Electrical:
    . Power conditioner a must ("TVSS", serial or parallel?)
      --> Issues with "nearby" 400 Amp digitial light dimmer?
    . UPS
      --> 15-30 minutes
      --> A/C probably can't be on, but would be good to have busses
           for any in-cabinet air-flow units
    . Grounding scheme

 . Plugs, cable runs, "ground plane" (transient) busses, etc.

 . Ceiling:
    . Vapor barrier
    . MUST include flexibility for things like re-routable return-air ducting
       with in-duct "fans", coupling to A/C intake plenum, etc.

 . Floor:
    . 18-24 inches (as tall as is reasonable is preferred.)
      --> Seismic bracing requirements?
    . 1250 lbs tiles, minimum.
    . Cable trays just under the floor.

 . Ramp:
    . Landing must be clear of equipment
    . Weight capacity:  ~3 tons
    . Tilt angle:  should be conservative - significantly less than the least
       of: (a) ADA requirements; (b) heavy rack safety requirements; (c) that
       required NOT to mid-point bottom-out long equipment.

 . Extra-height equipment access door (8' x 10')
   --> Admits tallest possible equipment, riding up already-rising ramp

 . Lighting:  "minimal" ambiant, with artsy track spotlighting (see example
    photos.)
   --> Lighting was one big, consistent complain with other machine rooms...

 . Fire suppression:  two-stage ("pre-action") dual-zone water system.
   --> Stage piping to everywhere, but be careful not to activate heads too close
        existing building power distrib units.

 . Alarm system
    . Swipe card system
    . HIPPA compliant, if possible.
    . Integrated with entire building??

 . Walls:
    . "standard" Class A data center requirements.
    . Lots of questions of "short" walls near stairs and at edge of current
       floor...

 . Windows (and punchouts for later windows)
   --> Keep locations in mind for A/C and vib isolation purposes

 . Vibration/sound isolation issues...