He has been working with his father Much Untertrifaller senior since 1982 and his Silvretta house on the Bielerhöhe marked a change in alpine building. Mid 1980s, the successful collaboration with Helmut Dietrich began. In 1994, after winning the international competition for the Festspielhaus in Bregenz, they opened their joint practice in Bregenz. The successful competition for the extension of the Wiener Stadthalle resulted in a second office in Vienna. In 2005, they established a branch in St Gallen, joining forces with Christof Stäheli. In 2015, the office in Paris was opened, followed by Munich in 2016.
Since 2016, Much Untertrifaller has been teaching as an honorary professor at the Konstanz University of Applied Sciences. He is i.a. president of the ZV (Central Association of Austrian Architects) Vorarlberg and member of the design advisory board Graz, Kassel, Landshut and Bezau.

She worked in the building consultancy branch before turning to the research world and starting in 2018 an industrial PhD in a collaboration between Saint-Gobain Nordic and the Technical University of Denmark. In her research, she collaborated with social scientists to collect end-users’ perspectives on their low-energy homes and the technical systems in them, highlighting the existing barriers to energy efficiency and comfort in practice. After completing her PhD, she joined VELUX as an indoor climate specialist in June 2021, where she continues to promote homes that benefit both people and planet.

He is responsible for a number of projects that exclusively deal with destination development within sustainable nature and cultural tourism, with a cross-cutting focus on experience economy. His approach draws on NORRØN's working method, which is based on the place's inherent qualities and cultural heritage. The projects have in common that they are all developed with a high degree of “sense of place”, which seeks to stage the inherent narratives as a lever for future development. In parallel, the projects are most often developed with a high degree of involvement of the developer, which is often a mixture of enthusiasts, organizations, the public and foundations. The ambition is to produce projects where the individual place can recognize itself in the final project.

The firm’s main focus is public projects that devote special attention to the surrounding natural and rural landscape. From the very beginning, the firm's main means of obtaining commissions has been participating in European and local design competitions and calls for bids. The architects live and work in Falzes, a small village in South Tyrol positioned on a sunny plateau near Bruneck. Among the projects authored by the firm is the alpine hut at the Sasso Nero (I), the house of cultural societies in Scaleres (I), the fire station in Riomolino/Montassilone (I), the kindergarten and the town hall in Predoi (I), the professional hotel school "Savoy" in Merano (I) and the gymnasium for sport climbing in Bruneck (I).

Since starting working together on the very next day after their graduation, Philipp, Christian and their partners have explored the architectural world with an unbiased and fresh view, fundamentally untouched by established architectural routines. Coming from one of the smallest and most sprawling countries in Europe, the responsible use of ground soil and the intelligent reanimation of existing buildings have become ever-growing interests for smartvoll in the last couple of years.