Through the refurbishment and extension of the Lavater school complex, an important testimony to Zurich’s school architecture has been preserved and updated for future generations. The building ensemble from 1896/97, designed by city architect Gustav Gull in the style of the Swiss National Museum in Zurich, is an excellent example of the sensitive interplay between historic fabric and modern technology.
Particular attention was paid to the refurbishment of the historic windows, which were carefully restored in line with heritage requirements by Holzmanufaktur SWISS AG, partner company of Holzmanufaktur Rottweil, specialists in historic timber window restoration – now featuring modern insulating glazing and the high-performance warm edge spacer bar Swisspacer Ultimate in the glazing edge.
During the restoration of the historic sandstone façade, the original windows were carefully renovated and fitted with new insulating glazing. Automatically controlled fabric awnings provide heat protection in summer. The implementation of the window solutions is a prime example of how energy performance can be combined with historic preservation requirements.
The original composite windows were largely retained in their original design, but were technically upgraded. While the historic interior glass could be preserved, modern insulating glazing with Planiclear and ECLAZ ONE coatings was used on the exterior. The high standards for careful installation in the historic building required complex logistics for the installation – including the use of a crane and special transport boxes for the upper windows.
The insulating glass unit achieves a Ug value of 1.4 W/m²K – a balanced value from both a technical and economic point of view. In combination with the Swisspacer Ultimate in the glazing edge, this results in a particularly energy-efficient overall construction.
“For a project like Lavater, which is subject to both heritage conservation and energy efficiency requirements, it was important for us to choose a spacer bar that could deliver both technological performance and design restraint. Swisspacer Ultimate impressed us with its excellent Psi-values, its matte, understated appearance and its discreet technical perforation,” said Dirk Obser, project manager at Holzmanufaktur Rottweil. Even the smallest component fits into an overall concept that combines monument protection, sustainability and everyday practicality in a remarkable way.
