Energie AG, Linz

Energie AG “Power Tower” – Linz, Austria
Project overview

The Power Tower in Linz is the headquarters of Energie AG, the energy utility for Upper Austria. Completed in 2008 and standing 73 m tall, the building was among the first high‑rise projects to adopt a ventilated double‑skin façade with active humidity control. The tower contains offices and meeting rooms for over 500 employees.

Design challenge

Linz experiences cold winters and warm summers. The tower’s large glass façades had to provide high levels of daylight while preventing overheating and condensation within the double skin. Conventional shading systems would be exposed to weather and would require regular maintenance, which is challenging on a high‑rise. Additionally, the façade needed to facilitate natural ventilation to reduce mechanical cooling loads.

RetroSolar strategy

The building uses a LEDS (low‑energy double‑skin) facade developed by GIG, incorporating RETROFlex louvers protected behind the outer glass
retrosolar.us
. The double skin is ventilated, and an active humidity control system manages moisture to prevent condensation. The louvers reflect sunlight before it enters the cavity, achieving g‑values between 0.05–0.10 when the blinds are open and a U‑value of around 0.5 W/(m²·K)
retrosolar.us
. The inner façade can be opened for maintenance. By placing the louvers in the cavity, the design protects them from weather and ensures consistent performance.

Building physics and performance

The ventilated double skin works like a chimney, drawing air upward and removing heat from the cavity. The retro‑reflective louvers prevent most solar radiation from entering the cavity in the first place, further reducing heat build‑up. The active humidity control system ensures that condensation does not form on the inner glazing, which could otherwise obscure views and damage materials. The combination of low g‑values and effective ventilation results in a comfortable indoor climate with reduced energy consumption.

Architectural outcome and significance

The Power Tower’s façade presents a crisp, modern appearance and demonstrates that high‑rise office buildings can achieve high environmental performance in Central Europe. The project showcases the synergy between retro‑reflective louvers, double‑skin façades and humidity control. Its success has influenced other utilities and corporate headquarters seeking to combine sustainability with a landmark presence.