Most of Erasmus students of the university are accommodated in families in Tallaght near the university. Indeed, the journey from the university to the city center is approximately 40 minutes and public transport are expensive. However, I decided to live in the city center of Dublin for several reasons: Firstly, we had only 3 days per week of courses, the rest of the time being devoted to the work of group or personal work, I prefered therefore live in the city center in order to do activities during my free time, such as visit, shopping, join friends, going to the cinema etc, more simply and more quickly than if I lived in Tallaght. Secondly, I wanted to live in collocation with foreigners to improve my English level. Most of sharing accomodations are in Dublin city center.
Sharing accomodation is very common in Dublin, there are many offers but also a lot of requests. You can find a sharing apartement via Facebook groups: Les français expatriés à Dublin or Dublin Flat Share International Flatmates group. In addition, the best site for finding an accomodation is daft.ie. It is on this site that I found mine, I was housed in Dublin 8 at Griffith College (a university in the heart of Dublin, which hosts many Erasmus students) in an apartment for 5 people with 2 Irish, 1 American and 1 French. Each of us had a single room, a bathroom to share with 2 (or 3) and a common kitchen and lounge. As you can see on the picture there are two large buildings at the bottom (surrounded) devoted to housing. Housing included a cafeteria with a Starbucks, a sports hall, and sports facilities such as a football pitch.
This accommodation was situated to 20 minutes walk from the center (5-10 minutes by bus) and 35 minutes by bus from the Insititute of Technology Tallaght.