Key legal question
Whether the cantonal court arbitrarily applied Art. 80 al. 2 LATC to allow conversion of the existing building into housing.
Extracted holding
No arbitrariness was shown; the conversion could be authorized within the existing volume because it did not sensibly impair the zone's development or destination and did not aggravate the regulatory nonconformity.
Extracted reasoning
The building had formerly been used for housing and the zone itself was residential. The court could reasonably treat the project as a transformation of an existing nonconforming building rather than a new inadmissible use, even though the municipal minimum surface rule was not met.