CABE's design review committee claimed both schemes "compete with each other and do not respond to wider urban issues".
It said the Granby Halls site, which combines a fire station, hotel, fitness club, shops and student housing in a triangular courtyard building, would leave the student rooms facing the courtyard deprived of daylight and privacy.
CABE also took issue with the plans to redevelop the north stand of the rugby club, which includes student housing and flats. "The block and the tower will create a vast amount of overshadowing and wind funnelling over the concourse and the Granby Halls site," it said.
n CABE last week blamed "a pervasive compensation culture" for turning Britain's parks and public spaces into "fun-free, soulless space". Backed by deputy prime minister John Prescott, CABE urged local authorities to make creating and caring for parks, streets and public spaces "a national and local political priority".