Case Study: nZEC - Energy refurbishment of 50 dwellings in Makartstrasse, Linz, Austria (UNDER MONITORING)

Short Description

The r project is the first project of retrofitting a multi-family block into passive house standard. Moreover some other aspects of modernisation are of interest; since the 5-storey building was not equipped with elevators, 4 elevators were built in.

The building is situated along a noisy street; the former balconies were of little use and were transformed into loggias. A very specific feature of the project is the façade which is a pre-fabricated panel system of a ventilated solar façade.

The buildings/dwellings were connected to the district heating. The disturbance of the residents during the modernisation process was reduced to a minimum.

Key Elements

Certification

Calculated energy demand space heating:

• before  renovation 179 kWh/m2(gross)
• after renovation: 13,3 kWh/m2(gross)
  
  
  

Work with Residents

For the modernisation process of a building integration of residents is a key issue. It offers the chance to empower residents to live with new technologies. In the case of this project residents were informed and instructed in individual and group meetings.

Funding

Mix of own funds, bank loan and public subsidy. Extra grant for innovative renovation from federal ministry.

Thermal Insulation

The insulation of the basement and roof was improved. A special solar façade was installed which not only functions as insulation but also makes passive use of sun light to temper the façade (cellulose comb behind glass panel). Due to a special combination of elements, overheating during the summer period is prevented. (GAP-system)

U-Value roof: before 0,9 and  0,094W/m2K after renovation                                                         

U-Value basement: before 0,7 and 0,21 W/m2K after renovation

U-Value façade: before 1,2  and 0,082 W/m2K after renovation (dynamic depending on solar input)

Windows and Shading

Passive house windows with integrated sun protection. U-Value: 0,86 W/m2K.

Ventilation

Each dwelling is equipped with automatic ventilation unit including heat recovery.

Heating and Hot Water

District heating.

Monitoring

Click here to access the monitoring data on the HIVE Database!

Main Results

The project is the first multi-family block retrofitted to passive house standard in Austria.  Specific features (solar façade) were used to obtain this standard.

The energy aspects are not the only one scheming the modernisation measures:

• Missing elevators were built in, the building/dwellings were connected to the district heating.
• The balconies were covered to make them usable.
• As the building is situated alongside a noisy street the passive house standard (automatic ventilation) leads to more comfort for residents as the system prevents ventilation by opening windows.
  
  
  

Lessons learned

The project was a rather costly modernisation not only to the energetic aspects but also due to the built-in elevators. Costs for energetic aspects were estimated to be 30% of total costs, the passive house standard causing a plus of 27%.

The estimated costs of heating costs were estimated to 80% of the former level; the first years showed that this reduction was overrated but still is about 50%. Since there is public assistance for financing there are no additional costs for tenants to cover costs of construction.

Additional Information

Ms Eva Bauer
Gbv - The Austrian Federation of Limited Profit Housing Associations
E-mail: ebauer@gbv.at
Web: www.gbv.at