Take No. 3 (from Zurich main station) or No. 8 (from Bellevue) towards Klusplatz and get off at Hottingerplatz. The institute building is at the corner of Freiestrasse / Steinwiesstrasse, in the immediate vicinity of the district school Rämibühl.
From Bellevue: Follow Rämistrasse to Kunsthaus / Schauspielhaus (Heimplatz), then turn right into Hottingerstrasse. After 300 meters turn left into Steinwiesstrasse and use the parking areas of the blue zone.