Question juridique clé
Whether an all-sided closed winter garden must be included in the gross floor area for the floor-area ratio calculation.
Solution extraite
Yes. A fully enclosed winter garden is attributable to the residential use of the building and must be counted in the gross floor area.
Motifs extraits
The court held that the planned winter garden directly serves residential use. The absence of heating is irrelevant because solar gain allows use as an occupied room for much of the year. The wording of § 34 para. 2 KBR and Annex III gives no basis to exclude winter gardens; only open ground-floor halls are exempt, not enclosed ones. Energy-saving provisions did not justify a different interpretation.