Heat Pump Cascade and Cooling System in Bremen, Germany
Located in Bremen, Germany, this modern multi-family residential building was constructed in 2017 with a strong focus on energy efficiency and sustainability. The core idea behind the project was to implement an innovative heating and cooling solution that minimizes carbon emissions while ensuring maximum comfort for residents.
At the heart of the system is a cascade of Mitsubishi Ecodan air-to-water heat pumps, delivering reliable and efficient heating via low-temperature underfloor heating. This monoenergetic system fully replaces fossil fuels, reflecting a commitment to environmentally friendly technology. Some of the project’s unique selling points (USPs) include its centralized heat pump cascade setup that provides both space heating and domestic hot water with a high degree of redundancy and smart control. The building meets the stringent KfW Efficiency House 55 standard, featuring advanced insulation, triple glazing, and mechanical ventilation to complement the heat pump system’s performance.
This project serves as an example of how modern heat pump technology can be scaled up effectively for multi-family dwellings, balancing energy savings, sustainability, and occupant comfort. Jürgen Steinbach explains:
“We also chose heat pump technology to demonstrate that
it can be used to heat a building very economically without
using fossil fuels. And our tenants find this very attractive.”
Key facts
| Building | Heat Pump and Source | ||
| Location | Bremen, Germany | Number of HP | 3 |
| Construction | 2017 | Operation mode | Monoenergetic |
| Heated area | 900 m² | Heat source | Outside air |
| No. of apartments | 8 | Type of system | Central |
| Level of insulation | Very good | Model | Mitsubishi Ecodan |
| Heating sytem | Domestic Hot Water | ||
| Heating temperature | 30-35°C | Max. temperature | 50-53°C |
| Installed power | 3 x 11,2 kW | ||
| Other information | |||
| Climatic zone | Cfb | Coefficient of Performance | 3,0 |
| Refrigerant | R1234ze |
Description of the technical concept
The building’s thermal system uses a modular heat pump cascade with Ecodan air-to-water units configured for staged operation. Each unit activates based on load demand, improving part-load efficiency and ensuring redundancy. A hydraulic module manages flow distribution, while an integrated buffer tank stabilizes supply temperatures during peak or variable demand periods.
Domestic hot water production is decoupled via a stratified storage system, enabling simultaneous DHW and space heating without performance loss. System control is handled by a central logic controller with temperature sensors and weather-compensated algorithms to optimize runtime and reduce cycling. The system is designed for low supply temperatures, enhancing overall COP and reducing auxiliary energy input.
Case study delivered by: Bundesverband Wärmepumpe (BWP) & Mitsubishi Electric