The International Energy Conservation Code (IECC) has a building energy efficiency standard with separate sections for commercial and residential buildings. In this link to the 2009 IECC, you'll see that the Residential section has requirements for envelope, HVAC systems, and electric lighting systems. Lighting systems specify "a minimum of 50 percent of the lamps in permanently installed lighting fixtures shall be high-efficacy lamps", which leaves application of the requirement open to interpretation. As for occupant density, there is no direct requirement from IECC 2009. These requirements may have changed, and you should double-check.

Another option would be ASHRAE Standard 90.2. On the ASHRAE website it looks like the last version was from 2007. I haven't used this standard myself, but would imagine it has similar requirements as ASHRAE Standard 90.1 for non-residential buildings.