PEB - Plus-Energy-Office

An integrated technical energy plus office concept without additional building costs demonstrates the feasibility of such projects instancing a concrete office project with 50.000 m² floor area in Vienna with economical cost consideration.

Short Description




The aim of this project was to develop an integrated technical plus energy office concept without significant additional building costs in consideration of current economic and legal market conditions for the realisation of a specific office project with 50.000 m² floor area in Vienna. The main focus is the innovative overall concept of the building technology, beside the obvious goal of improving the thermal quality of the building envelope to passive building standard.

An analysis of user needs was done in form of a user survey in existing conventional and energy saving office buildings in Vienna. The comments of employees were startling as results showed that room temperature regulation has little or no relevance, though the quality of room air, daylight and noise were named to have substantial influences on staff performance.

Through simulation it was shown that cooling, ventilation, lighting and office devices have the greatest primary energy demand. With all energy saving methods the primary energy demand could be reduced to one third of the default value. The primary energy and the energy demand of office devices of the reference building is 531 kWh/(m².BGF.a) This value could be reduced to 164 kWh/(m².BGF.a)

The primary energy parameter for electricity of 3,5 kWH/kWH was assumed and for heat from district heating the parameter of 1,0 kWH/kWH. Through the use of a closed loop system, heating energy was saved, but the energy used for humidification showed a negative overall result.

Under compliance of certain requirements, realisation of a plus-energy-building for the two low-rise buildings is technically possible. The high-rise buildings do not necessarily allow for realisation due to the ratio of overall usable space to the small roof area. The comparison of the calculated consumption shows, that both the general operation expenses as well as the specific energy consumption of tenants within the reference building can be reduced by two thirds in the plus-energy-building.

The additional costs for the plus energy office are around 19 % accuracy at a cost inaccuracy of 10-15%. To create economic incentives for the higher financial investment, space should be offered with “warm rents”. With this model the total costs for tenants will remain the same, as for refinancing the higher net rent will be calculated against the energy savings of the tenants. For a plus-energy-office, tenants will have to accept higher expenses as well if passive building standards are realised, expenses with “warm leases” will raise up to EUR 0,5/m² NF.

Project Partners

Project management

DI Birgit Reiß
BAI Bauträger Austria Immobilien GmbH

Project or cooperation partner

  • DI Helmut Schöberl
    Schöberl & Pöll GmbH
  • DI Markus Leeb, Ao.Univ.Prof. Dipl.-Ing. Dr. Thomas Bednar
    TU Wien, Institut für Hochbau und Technologie, Forschungsbereich für Bauphysik und Schallschutz

Contact Address

BAI Bauträger Austria Immobilien GmbH
DI Birgit Reiß
Leopold-Moses-Gasse 4, A-1020 Wien
Tel.:/Fax: + 43 (1) 33146 - 4218