New and newly altered (remodeled) residential construction is required to meet the 2016 California Energy Efficiency Standards, more commonly referred to as "Title 24" or "Title 24 Energy Requirements". Efficient lighting reduces your cooling loads and your electrical bills while providing better quality lighting making your home more comfortable.
The following is a comprehensive understanding and some of the options available to the designer, contractor, and homeowner download the full Title 24 Residential Design Guidelines pamphlet. http://cltc.ucdavis.edu/sites/default/files/files/publication/161102_2016_Title24_Residential_Lighting_Guide_web_0.pdf
Significant changes in the 2016 Energy Efficiency Standards for dwellings: http://cltc.ucdavis.edu/sites/default/files/files/publication/2016_T24_Res_Changes_Jun2016_Update.pdf