Residential complex Dennlerstrasse

Sustainable heating in existing buildings

The residential complex owned by the pension fund of the Siemens companies in Switzerland, located on Dennlerstrasse in Zurich, is breaking new ground: the complex has recently switched to CO₂-neutral heating.

In the early 2000s, the Dennlerstrasse residential complex in Zurich-Albisrieden was built on the site of a former allotment garden. The complex, which is owned by the Siemens Pension Fund and was designed by the renowned Zurich architect Theo Hotz, consists of two terraced buildings and five standalone buildings. Even after some 20 years, the complex generally meets current efficiency standards.

However, as the owner, the Siemens Pension Fund identified potential for optimization in the area of energy supply. A feasibility study showed that the flat roof of the longer row building was well-suited for a solar system. Consequently, 352 photovoltaic modules were installed as early as 2024. A somewhat larger renovation project arose in the area of the development’s heating supply.

Our investigation revealed that the municipal network will not be able to provide service to the Dennlerstrasse neighborhood in the coming years. We therefore had to develop a standalone solution for the area

Steffen Ringlau, Energy Engineer and Project Manager, Siemens Switzerland

Renewable alternative

Since the Siemens Pension Fund’s real estate strategy calls for replacing fossil fuel heating systems in existing properties with zero-emission solutions at the end of their lifecycle, a one-to-one replacement of the gas boilers was out of the question. The Siemens Pension Fund commissioned Siemens to identify, plan, and implement a renewable alternative. The most obvious option was examined first: connecting to a district heating network.

dennlerstrasse-technischer-speicher original

Advanced heating system with maximum reliability of supply

The Siemens experts from Smart Infrastructure Sustainability developed an advanced heating concept that offers a smart expansion of existing systems and maximum supply reliability. Given the urban location, various requirements – including regulations regarding the creation of ruderal areas – had to be taken into account. The goal was to develop a practical and sustainable solution for renewable heat generation.

The 164 apartments, which were previously heated by a base-load heat pump and gas boilers, now benefit from two high-performance ground-water heat pumps with a total heating capacity of nearly 600 kW. This system upgrade was complemented by the installation of 18 new ground probes, which, together with the existing 17 probes, provide a reliable heat supply. A technical storage tank was installed to hydraulically separate the water circuits between the heat sources and the heat pump, thereby balancing out fluctuations in pressure, temperature, and flow.

A central component of the project is the air heat exchanger on the roof of Dennlerstrasse, which serves both as an additional heat source for the heat pumps and contributes to the regeneration of the ground. This ensures the long-term efficiency of the heat pumps. The generated heat flows into a new local heating network that efficiently and evenly supplies all seven buildings in the development.

Here's how decarbonization works

This future-oriented project is compelling from both an environmental and economic standpoint: With annual operating cost savings of around 25,000 Swiss francs, both the Siemens Pension Fund and the residents stand to benefit. The project demonstrates how the heating system in an existing building – which, apart from the energy supply, requires no renovation – can be modernized, and that there are indeed feasible options for the challenging task of decarbonization. To monitor efficiency and energy consumption, a modern energy monitoring system from Siemens was installed as part of the project. This allows the system’s performance to be monitored and ensured.

With this modernization, the Siemens Pension Fund is sending a clear signal for sustainability and demonstrating how technological innovations can contribute to creating a more environmentally friendly and economically stable future.

dennlerstrasse-luftwaermetauscher original

Contact

For more information or inquiries, please contact Steffen Ringlau.