By public transport
Plan your trip online via SBB.
In Zurich main station take the S-Bahn line S5 to Birmensdorf (final destination: Zug) or S14 (final destination: Affoltern am Albis), travel time ca. 20 minutes.
From Birmensdorf train station take postal bus no. 350 for two stops to Sternen/WSL.
Alternatively, walk about 25 minutes.
By tram/postal bus: Take the tram no. 14 to the final destimation (Triemli). On the opposite side of the road you can take either postal bus no. 350 or 220 to the WSL (stop: Sternen/WSL).
You find guest parking spots (for a fee) behind the main building after passing the main entrance.