Facts
On 11 March 1986, Insurance Company X. leased a four-and-a-half-room apartment in Geneva to B. The lease, concluded for the period from 1 May 1986 to 31 March 1987, was tacitly renewed for new periods. The initial annual rent was 10,440 francs. The reference mortgage interest rate was 5 1/2% at the time, then reduced to 5 1/4% on 1 April 1987, to 5% on 1 September 1988, and subsequently increased to 5 1/2% on 1 July 1989 and to 6% on 1 October 1989.
The landlord notified her tenant of three rent increases: the first on 10 December 1987, the second on 9 June 1989, and the third on 8 December 1989. The tenant opposed the third rent increase, which would have raised the annual rent to 12,792 francs.
The Geneva Rent and Lease Tribunal dismissed the plaintiff's claims, but the Rent and Lease Appeal Chamber annulled the first-instance judgment and set the annual rent at 12,792 francs.
Considerations
The Federal Tribunal examined the validity of the disputed rent increase based on the reference mortgage interest rate and the calculation method. It considered that the date of the last rent fixing is, in principle, that of the entry into force of the last rent, but that this rule can be nuanced depending on the circumstances.
The Federal Tribunal also examined the application of art. 9 al. 2bis RRBPO, which provides that in the event of a rent change due to a change in the mortgage interest rate, it must be determined whether and to what extent previous changes have been passed on. It considered that the retrospective verification must be made by referring to the actual rent changes that occurred during the period to be considered and re-examining them successively, according to the relative method.
The…