The well-tempered Environment of the WU


Barbara Weber

In order to find out whether big and modern are bad, I tried to dismantle the complexity of the mega structure of the University of Economics by focusing on one of its major elements: the climatic unit. Consisting of fluorescent lamps, windows with a solar protection coating, nozzles for air-conditioning and fan coil units; this element or module creates the so-called well-tempered environment of the WU. While investigating this unit on a large scale, I asked the following questions:

Do all of those interventions truly create a well-tempered environment?

Should we rather speak of the audacity of air-conditioning if an infinite number of nozzles deny the possibility of air exchange through open windows? 

How do hollowed fan coil units suit the honesty of modern architecture?

Can the climatic problems of mega structures simply be solved through sufficient mechanical interventions?

The climatic cover of WU is a warm, non rear-ventilated facade. Sitting on an element construction in aluminium profiles prefabricated window elements (PARELIO K50) enclose the whole structure. PARELIO K50 is a double-glazed window construction with one layer of metal-oxide coated prestressed mirror glass. The coating reflects the infrared rays on the outer layer, letting the part of radiation perceivable by the human eye into the room to ensure high natural illumination. Held by aluminium frames which have neither insulation nor thermal isolation, the window element has a rather poor thermal performance. As a result the overall facade is responsible for high heat losses as the heat transfer coefficient of 3 W/m2K indicates.

To prevent large buildings with glass facades from excessive heating air-condition systems with duct outlets are installed. In the case of WU fresh air is conditioned in plants on top of the building and distributed in ducts below the concrete slab and in between shafts. On top of each window four metal nozzles stream hot or cold air into the rooms. According to the norm lecture rooms should have an air volume flow rate of 30 m³/h per person. The average air velocity should not be higher than 0,2 m/s with maximum turbulences of 5% .

For additional heating, cooling and dehumidification of the circulating air, fan coil units are installed below each window module. These units are supplied by hot or cold water from district heating in Spittelau, which is distributed through pipes, and ducts that run between the construction slab and the suspended ceiling. A ventilator on the bottom of each unit blows the room air over the hot or cold pipes, resulting drafts and turbulences of mixed air can cause discomfort.