Altbach, Germany
The project in Altbach (near Baden-Wurttemberg’s capital of Stuttgart) was completed in 2021. The three multi-family buildings (MFBs) with eight dwellings each and a shared parking garage comprise a total living area of 1753 m² and were built to the KfW-55 standard.
Lessons learned
- Running DHW separate from SH allows for more efficiency since in the underfloor heaters, the SH water does not need to be heated to more than 35°C.
Key facts
| Building | Heat Pump and Source | ||
| Location | Altbach, Germany | Number of HP | 6 /2 per building) |
| Construction | 2021 | Operation mode | monoenergetic |
| No. of buildings | 3 | Heat source | solar / PVT |
| No. of aparments | 24 (8 each) | Type of system | central |
| Level of insulation | good | ||
| Heated space | 1753 m² | ||
| Space Heating | Domestic Hot Water | ||
| Type of system | central | Type of system | central + “decentral” |
| Heating temp. | 35°C | Heating temp. | >50°C |
| Heat distribution | underfloor | Connection to apartment | Fresh Water Stations “decentral” |
| Storage | 800l | ||
| Other information | |||
| Climate Zone | Cfb | Refrigerant | R410A |
| PVT | 108 collectors (36 per building) | ||
Description of technical details
Every house has 36 photovoltaic-thermal (PVT) collectors on its roof which feed each building’s two central heat pumps.
The hydraulic connection to the apartments happens via a four-wire system, meaning that there is separate piping for Space Heating (SH) and Domestic Hot Water.
This improves the total efficiency of the system as the heat pump for the underfloor SH can be run on low-temperature settings. It has a flow temperature of merely 35°C (max.) and it includes an 800l storage unit in each building.
Domestic Hot Water is provided by each MFB’s other heat pump which heats water to a temperature above 50° and transfer the heat to the apartments’ decentral Fresh Water Stations.
DE016 – PVT-Heat-Pump-System for three MFBs
Case study delivered by: Bundesverband Wärmepumpe bwp BWP-Datenbank | Bundesverband Wärmepumpe (BWP) e.V.