Case Study: nZEC - New construction of 354 dwellings in General Eccher Strasse, Innsbruck, Austria (UNDER MONITORING)

Short Description

In cooperation with the planning staff of the City of Innsbruck and the chamber of Architects, an architecture competition was launched in 2006. In an unanimous decision of the jury, the architecture office of Markus Prackwieser, Conrad Messner and Othmar Zobl won the competition. This office then started to develop the urban renewal concept- together with the Municipal authority for urban development and Neue Heimat Tirol.

From December 2007 to September 2009 354 rental dwellings were erected to passive-house standards which are certified by Passivhausinstitut Darmstadt.
The philosophy of the project strives to minimize energy costs and rents for the tenets on the long run with a modern architecture and an outstanding technical management.
Of a great importance were also a good building envelope, no technical gadgets, user-friendliness, low heating and operating cost, protection of the environment, independence from energy suppliers.

Key Elements

Certification

• The studio’s total project package aimed to achieve the highest passive construction standard possibile. Initially, the biggest challenge was the required construction volume which exceeded all the energy-efficient residential developments built in Europe up to that date.
• In order to comply with these requirements, the project was constantly surveyed and certified by the renowned Institute for Passive Construction Darmstadt under the aegis of Professor Wolfgang Feist.
• The development is the biggest completed construction unit in Europe that complies with the latest certified passive construction standards.
  
  
  

Capacity Building

• A complete team was sert up for the planning the passive-house Lodenareal, with representatives of neue heimat and allo other stakeholder involved.
• During the construction phase, a show flat was arranged to enable the implementation of all technical details and to train involved craftsmen.
• To guarantee the quality of the execution, the detailed building planning was carried out by the architects. Cost calculation was made by the the municipal building inspectionthrough Neue Heimat Tirol, who also placed the orders for the individual crafts.
• Numerous visits and further training enabled the team members to enhance their knowledge and skills.
• Improved technical demands make building costs 7% higher. These get nearly completely subsidised by public authorities.
  
  
  

Heating and Hot Water

• A central heating  located between the two building blocks is dstribuiting heat to the individual buildings. Heat is generated with a pellets boiler and a gas condensing boiler, 80% of the annual energy demand is covered by pellets.  
• Heating Demand: 14.5 W/m²Ka (4.43kBTU/ft²/a). Thanks to the low heating demand only pheripheral zones of rooms are heated with the floor heating.
  
  
  

Solar Thermal

• About 1050sq meters of solar collectors are installed on the roofs. This is the equivalent of about 3swm per flat, The actual energy supply of the solar palnt stands for at least 350kWh/m2  collector surface.
• The energy generated by the solar plant  more than 367.500k/year. The gained energy is buffered with heat exchangers in 5 resp 6 buffer storages (per substation) with 2.500 litres each, stratified by means of switch valves and then fed into the supply pipework.
• The buffer storages are completely cased, hollow spaces are insulated with cellulose flakes, so that energy losses are minimized.
  
  
  

Ventilation

• Ventilation is centralized in the basement. The fresh air intake functions through a ventilation towers  with filters in the courtyard at a height of 3 meters. Air is tempered with cross-stream exchangers.
• Fresh air is supplied into the bed and living room with wall-mounted air diffuser. Due to the special sound absorber  the sound level at the air diffuser  level is only about 22db.
  
  
  

Air Tightness

Airtightness: 0.20 ACH50.

Windows and Shading

Triple glazed Windows, U-value=0.78 W/m²K (R-7.5).

Work with Residents

One of the objectives was raising awareness on ecological concerns. Anyway, in the Passivhause-condomnium LODENAREAL, energy consumption remains constantly low, independent of the user behaviour.

Monitoring

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

Main Results

Energy:

• Reduction of the yearly production of CO2by 680 tons
• 80% lower energy demand
• Solid construction with a high-standard, airproof building envelope according to passive construction standards
• Approx. 1.050 m² solar panels (3 m² / living unit)
• Energy consumption < 15 kWh/m² per annum (according to PHPP, "Programm Passivhaus-Projektierungs-Paket”)
• Energy efficiency: class A++
• Controlled room ventilation / average air-exchange rate 0,35/h
• Blower Door-Test resulting in n50 =0,20 (clearly below the requested value of 0,60)
• Thermo-conducting cabling in the basement (insulation min. 1,5 times higher than required standards)
• Seismic load is transferred to interior staircases
• Constructive separation of structural components as prevention of thermal bridges
  
  

Rent (Annual account 2010):

• Warm water: € 0,10
• Heating: € 0,08
• Electricity ventilation: € 0,04
• Maintainance ventilation: € 0,10
• Total: € 0,32 per m² and month
• Rents: € 7,50 incl. additional costs (heating, warm water, parking garage)
• Cost-development: instead imported fossile energy main focus on domestic renewable energy sources – pellets and thermal solar
• Higher maintenance costs „eat away“ parts of energy savings
• 7 % higher building costs due to improved technical demands.  These get nearly completely subsidised by public authorities
  
  
  

Lessons learned

• Permanent development of knowledge – collaboration of  building contractor with research necessary.
• Passivhouse of the 2nd generation links innovative and minimized building service technology with ecological building and users‘ behaviour.
• Integrated Planning – connecting know-how in a chain between  project leader, planner, tenders, project supervisor and property manager throught the whole process.
• Construction development/Quality management on highest  possible level
• Technical features must align to the customer needs – not the other way round!
  
  
  

Additional Information

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