January 29, 2026
RICHMOND, Va. — The Virginia Department of Environmental Quality (DEQ) will require new air permit applications for diesel generators at data centers to meet Tier IV-equivalent emissions controls starting July 1, 2026, according to a Virginia Mercury report. The move is aimed at reducing harmful air pollutants from both emergency and non-emergency generators as the number of data centers continues to grow across Northern Virginia.
The DEQ guidance, which updates the agency’s presumptive Best Available Control Technology (BACT) for diesel engines, calls for generators to include technologies such as Selective Catalytic Reduction (SCR) for nitrogen oxides (NOₓ), Diesel Particulate Filters (DPF) for fine particulate matter (PM2.5), and Diesel Oxidation Catalysts (DOC) for carbon monoxide (CO). These controls are designed to dramatically cut emissions compared with older Tier II or Tier III engines.
Environmental advocates have raised concerns about air quality near clusters of data centers, warning that backup generators could significantly contribute to local pollution if used more often than in the past. The DEQ update reflects efforts to balance emergency power needs with cleaner air standards.
Facilities submitting permits after July 1, 2026 will need to comply with the Tier IV-equivalent standard or provide DEQ with justification for alternative control strategies.
For a detailed industry perspective and confirmation of the Tier IV BACT requirement, see Trinity Consultants.