The Milchgasse ward of the Golatti care center in Aarau's old town had to be completely renovated. The three listed houses have a remarkable past. As early as the 13th century, there was an Augustinian monastery there. The use of the building complex changed constantly: Latin school, asylum for the poor, silk ribbon factory, factory owner's residence and since 1852 as a municipal old people's home. How can the building be prepared for the future and be used as a nursing home for another 15-20 years?
Historic preservation versus thermal insulation
Grolimund + Partner, together with the architects Gemeinschaft 4 AG and the building services planners, developed a sustainable energy concept without full-surface insulation of the old walls and without a mechanical ventilation system. Since the houses are part of the Aarau city walls, their external appearance is protected. Thermal insulation from the outside was out of the question. Interior insulation was undesirable because of the loss of space and was also the wrong approach from a building physics point of view. For reasons of site protection, the roof areas could not be used for energy production either.
Eliminating thermal weak points
Finally, only the deep window reveals and the radiator niches were insulated on the inside. Together with the new windows, this eliminated the biggest weak points in the building envelope. At the same time, the thick walls could be retained as storage mass. The roofs of the three houses were very well insulated with U-values of 0.12 - 0.18 W/m2K. In addition to a large saving in heating requirements, this also leads to significantly cooler interior temperatures in summer. With the connection to the municipal district heating network, the nursing home will soon have largely renewable and climate-neutral heat generation.
Fresh air with low-tech
A ventilation system could only have been implemented in the nursing home's three connected buildings at great expense and with painful concessions in terms of space requirements. In the end, a technically simple approach was chosen: Individual window ventilation remains possible. Due to the exhaust fans in the bathrooms and the after-flow in the window rebate, the room air hygiene remains guaranteed. In terms of materials, attention was paid to natural and vapor-diffusing surfaces in the interior finishes: Clay plaster regulates humidity in the rooms and absorbs odors.
Sound insulation and room acoustics
For the existing wood-beam ceilings, Grolimund + Partner worked out acoustically acceptable solutions with the architects and specialist planners. Compromises were sometimes necessary. For example, a historic ceiling with floorboards painted in grisaille technique from the 17th century could be preserved.
Despite the low room heights, the room acoustics could be solved. In the recreation room, a baswaphone ceiling (jointless acoustic ceiling with white plaster look) provides visual and acoustic peace. In the offices, reverberation time measurements in the equipped and occupied office proved satisfactory acoustics - a pragmatic and expedient approach.
In the renovation of the Golatti nursing home in Aarau, the motto is "the best possible is good enough" rather than "only the best is good enough". The discreetly colored bright rooms have an inviting effect. The renovated buildings appear well-kept and yet are integrated into the existing old town in a restrained manner. An exemplary example of targeted intervention in existing buildings and great cooperation between all parties involved.