Seems I'm not alone in having trouble locating good information online about computer room environmental requirements (power, air-con, physical access controls, raised floor design etc.). A fellow infosec professional searching specifically for air-con parameters published some useful links on the CISSPforum today i.e. IBM, HP and more HP, Sun and the University of Texas. I recommended a book from the Sun Blueprints series by Rob Sneveley: Data Center Design and Methodology (~$62 from Amazon). I'm still looking for relevant standards.
More physical security links