For Commercial construction, the City of Dallas adopted an amended version of the 2009 International Energy Conservation Code on April 1st 2011. For Residential construction, the IECC was adopted on January 1st 2012. It is titled the Dallas Energy Conservation Code.
That code requires that any additions, alterations, renovations or repairs to existing building or residences shall conform to the provisions of this code. That includes any changes in occupancy that would result in an increase in demand for either fossil fuel or electrical energy shall also comply with this code.
See the Residential Energy Inspection Checklist for requirements for the Dallas Energy Code.