The purpose of this acqusition package is to replace an aging AHU to restore reliable, code-compliant environmental control; reduce operational and contamination risk; maintain environmental stability; and ensure continued compliance with applicable Federal, state, mechanical, and safety code requirements. Replacement of the AHU with a modern, high-efficiency system will support clean-room contamination control needs, improve energy performance, and ensure continued mission capability for NOAA and NIST research programs.