“The Dunaj Palace is a unique example of how architecture can not only harmonize with history, but also show the way to a sustainable future. LEED Gold certification confirms the successful combination of original constructivist architecture with modern technologies, materials and equipment: together they create high-quality and functional spaces that are environmentally friendly and financially friendly to our tenants, while reducing operating costs,” comments Peter Noack, co-founder and CEO of Zeitgeist Asset Management.
New buildings usually undergo LEED certification. That is why meeting the individual criteria for the reconstruction of a historic building was a real challenge. “The project was also made more difficult by the building’s location in the historic center of Prague, where the limited area of the land complicated the construction site and ensuring the availability of construction equipment. In addition, at the time of the start of the work, which also included demolition, some of the original tenants were still working in the building, so we had to ensure that the quality of the indoor environment for existing users was consistently ensured,” describes Petr Schorsch, head of the LEED department at Grinity.
Due to limited space around the construction site, the commonly used external construction dumps were replaced with internal ones. Bulky material was transported to the site using a crane from the roof of the building, which is a much more complex process compared to other construction sites where the material is transported directly to the site by ground transport. The limited space also complicated waste sorting, as it was not possible to place more bulk containers nearby to separate the individual types of construction and demolition waste. At one point, only one container could be brought in for collection. “Despite these limitations, the project managed to sort and recycle almost 90% of all construction and demolition waste, which was largely due to the demolition company Bau Grand Plus. This company clearly demonstrated that a building can be effectively dismantled and recycled in practice, not just demolished. The proof is the fact that the Dunaj Palace received the maximum number of points from the GBCI certification authority for waste sorting during demolition and construction,” says Petr Schorsch.
Emphasis was also placed on the selection of building materials. A total of 26 different materials with an environmental performance certificate (EPD) were used in the Dunaj Palace, and more than 15% of the materials contained recycled components. The requirement for preferential selection of materials compliant with the REACH directive was also met. This required the submission of an analysis of the content of harmful substances in the materials with an accuracy of 100 ppm, which is a significantly stricter requirement compared to the common European standard, which sets an accuracy of 1,000 ppm. For these adjustments and the search for the best options, the project received 3 points in the credits from the section focused on the disclosure and optimization of building materials. In addition, it received 1 point for composite wood and ceilings within the criterion focused on materials with low CO2 emissions.
The chosen roof also had a fundamental influence on the evaluation. The roof of the historic Dunaj Palace was not walkable. However, since a green roof is generally a great benefit for the building and the entire location, a wide discussion took place during the reconstruction. “The great cooperation of the entire team ultimately made it possible to design the roof in a way that meets the requirements of all stakeholders. The new roof will be accessible to all building users, which will create great opportunities for leisure, relaxation and meetings. At the same time, it will contribute to a better quality environment and reduce the heat island effect within dense urban areas,” says Michal Nečas, CEO of Zeitgeist Asset Management.
The greenery on the roof covers 31.5% of its total area and will be irrigated with an efficient drip irrigation system. The plantings were designed with plants of local origin or adapted to local conditions, which are also easy to water. Thanks to this, it will be possible to reduce the consumption of drinking water for irrigation by 100% compared to the LEED reference value. The implementation of the green roof of the Dunaj Palace brought a total of 7 points in various categories focused on territorial sustainability, effective water management and local needs.
The Dunaj Palace naturally received a higher score in the credit aimed at reducing the life cycle impacts of buildings – a total of 6 points for the reuse of a historic building. “However, the great news is that the Dunaj Palace managed to obtain 10 points in the criterion aimed at optimizing energy efficiency and achieve energy savings of 22.6% compared to the LEED reference value. This is a unique result for a renovated building, especially considering that the design of all technologies had to take into account the spatial constraints of the existing building, for example for the placement of technical equipment on the 1st and 2nd basement floors,” adds Petr Schorsch, adding that the Dunaj Palace ultimately achieved the Gold level with 64 points. The WELL indoor environment certification is currently still underway with the aim of also achieving the Gold level.
