Green building codes have failed to conserve energy use in the nation’s most populated state, according to a new study published by the National Bureau of Economic Research.

California, currently home to 12 percent of the United States population, enacted energy building codes for the first time in 1978. The codes were projected to reduce residential energy use and its associated pollution by 80 percent. Instead, buildings constructed after the green energy codes took effect are not using less energy than homes built prior to the codes.