The public transport in Switzerland is a good way to travel to and from ISAP and also to explore other parts of Zürich and Switzerland. For checking your itinerary you can use the timetable of the SBB.
There are different possibilities to get cheaper tickets. For information about train tickets you can check here.
For the canton of Zurich the public transport companies are combined under the organization ZVV. Find out more here and here.
Please be aware that there is a half-fare travelcard (Halbtax) that you can get for CHF185 for one year, that will give you a 50% discount on most tickets.