The municipality of Hausen am Albis at the southern tip of the canton of Zurich is nestled in an intact local recreation area that it shares with the Türlersee, Sihlwald and Seleger Moor. This attractive environment is the setting for the Rauchmatt site – one of the most important development zones in the municipality. A modern residential and commercial development is currently emerging on this site. The project comprises three apartment buildings with 36 rental apartments in the mid-price segment, six owner-occupied terraced houses and three commercial buildings. These new builds combine contemporary living with attractive commercial use and make an important contribution to high-quality local development.
- 110 kW heat output
- 16 geothermal probes at a depth of 220 m to 250 m
- 214 kWp PV output
- 205 MWh solar power production
- approx. 30% self-consumption of electricity with ZEV
- 130 meters for service charge billing (space heating, hot and cold water)
The groundbreaking ceremony in spring 2026 marked the start of the first phase of construction of the residential buildings. The buildings, which are located away from the main road amid generous green space, are built on a slope which offers a sweeping view of the nearby farmland and are accessed via a communal underground car park. Floor-to-ceiling windows create a bright living atmosphere. The exterior is marked by a timber façade ringed by horizontal bands. The three commercial buildings along the main road with floorspace of around 7,000 square metres are designed as wooden cubes measuring 30 by 30 metres and will be completed in the second phase of construction. With a restrained material profile dominated by timber, the ensemble enters into a dialogue with its surroundings and forms a smooth transition between the village centre and the neighbouring farmland.
For the private developers, it was clear from the outset that the energy supply for residential and commercial use had to meet high environmental standards. The aim was to achieve a 100 per cent climate-neutral solution from a full-service provider that can be trusted to provide all energy services from planning and construction to operation. The developers were impressed by ewz with its comprehensive energy concept and contracting model, as well as its extensive experience with comparable projects.
The core of the energy supply in the first construction stage is heat generation using geothermal probes. In spring 2026, 16 geothermal probes were drilled to a depth of 220 to 250 metres. According to the current schedule, in late summer 2027 the heat pumps installed in every building will start extracting thermal energy for heating and hot water from the underground probes. The heating system is equipped with technical storage systems that optimise the running times of the heat pump, while the day’s requirement of hot water is always produced in advance.
On hot summer days, the ground can be used for free cooling (also known as geocooling). As the cool water circulates through the rooms, it absorbs thermal energy and reduces the indoor temperature. This passive cooling method only uses the circulation pumps rather than the heat pump compressors. That makes free cooling an extremely energy-efficient cooling method, and one which also serves to regenerate the geothermal probes. The heat extracted from the interior is released to the ground via the probes, which counteracts long-term cooling and the diminishing efficiency of the heat pump.
To supply the apartments and terraced houses with renewable, locally produced electricity, the flat roofs of the three apartment buildings are fully covered with photovoltaic modules – around 1,000 square metres in total. PV modules will also be installed on commercial buildings at a later date. To ensure utmost efficiency in use of the solar power on site, ewz is establishing a self-consumption association (ZEV) for occupants of the residential area which will later extend to the users of the commercial buildings as well. This will increase self-consumption, improve the cost-effectiveness of the PV installation and relieve the pressure on the public electricity grid. ZEV participants will also benefit from lower energy costs, as solar power generated on site is cheaper than electricity from the grid.
To ensure optimal coordination of electricity production and consumption, heat pumps and other large consumers will operate when solar power output is high. Solar power for charging electric vehicles is a secondary priority. The self-consumption rate for solar power will be around 30 per cent. The PV system will produce more electricity than the site needs at any given time, so some of it will be fed into the local electricity grid, subject to payment by the grid operator. The large solar yield will also allow the solar power to be marketed in the future in the context of a local electricity community (LEG). Under the LEG model, electricity producers and end consumers join forces to use solar power within a municipality via the public distribution grid. This allows owners to further optimise the profitability of their PV systems, while consumers benefit from favourable terms for environmentally friendly electricity.
Initially, nine of the 70 parking spaces in the residential buildings will be equipped with charging stations. The remaining parking spaces will be equipped with basic infrastructure (in accordance with SIA information sheet 2060 ‘C1 – Power to Garage’). This means that additional wallboxes can be installed quickly if required. The ewz charging solution also includes billing for electric car owners. Dynamic load management will ensure optimal charging for all connected vehicles depending on the consumption of the complex as a whole.
ewz is planning, implementing, financing and operating the entire energy supply under an energy as a service model. ewz will also handle the billing of individual electricity consumption and the installation and operation of a softening system for drinking water. The advantage for the owners is that they won’t need a specially trained facility manager on site, which will reduce personnel and financial expenditure for maintenance.
The energy supply contract between the owner and ewz has a 30-year term. After that, there are two options: either the assets are transferred to the property owners or the contract is extended. Should the cooperation continue, ewz will keep operating the systems for a newly agreed term and will remain responsible for reliable operations.
Owners, residents and future users of the commercial spaces have the advantage that they can address any questions around the energy supply to a single point of contact who is familiar with the system. For the developers, the one-stop solution is particularly attractive with a view to security of supply. They outsource the financial and technical risk to ewz and benefit from 24/7 remote monitoring. In the event of operational disruption, ewz employees can be on hand to quickly resolve the problem. A further advantage for everyone involved is that the energy costs are stable and can be budgeted over several years.
Once the systems are commissioned, ewz will continuously record and review consumption data through remote monitoring. Analysis of this data will facilitate ongoing optimisation of the system during operations, with adjustments that meet the needs and habits of the users as required. The aim is efficient operation that keeps both energy consumption and costs to a minimum.
Since the Rauchmatt site will be built in two stages, the energy solution has to be planned and coordinated in good time for both construction phases. With ewz providing an integrated raft of services, the site can make the most of synergies in energy efficiency and cost-effectiveness.
Project participants
- developers: AG für Liegenschaften und Hypotheken (apartments); Münstergasse Zürich AG (commercial)
- General contractor/construction management: bau construct services ag, Zumikon
- Architecture: Leutwyler Partner Architekten AG, Zug/Zurich
- Specialist HVAC planner: tib Technik im Bau AG, Lucerne
