Operating expense ratio — total operating costs divided by effective gross income — is a blunt instrument. In regional office markets it still earns a place on the first page of a portfolio brief because it surfaces maintenance habits and management fee structures faster than NOI alone.

When comparing a Gwangju CBD tower to a suburban flex building in Seo-gu, three line items usually explain most of the gap: HVAC contract scope, security staffing hours, and elevator maintenance reserves.

HVAC contracts vary by floor plate

Older CBD buildings often run central chillers with costs allocated by rentable area. Flex assets may use split units billed directly to tenants. A ratio comparison without footnoting HVAC allocation method will punish the wrong asset.

Management fees hide in different accounts

Some operators book property management as a separate invoice; others embed it in repairs and maintenance. We normalise these entries before plotting a peer chart so a 32% ratio is not compared against a 28% ratio that excludes management.

For portfolios under fifteen assets, we suggest tracking ratio trend over eight quarters rather than chasing a single benchmark number. Direction matters as much as level when capex cycles run on multi-year intervals.