IEA Solar Heating and Cooling Programm - NachhaltigWirtschaften.at

IEA SHC Task 38 Solar Air Conditioning and Refrigeration Subtask A Report A-D3b, Date: December 2010
2.5 Austria: Office Building Feistritzwerke, Gleisdorf
Description of the application
The office building of the Feistritzwerke STEWEAG GmbH, a municipal energy and water
supplier, was renovated in 1995 and was equipped with a solar heating and cooling device in
June 2010 for air conditioning both floors of the office building. Before that, no air
conditioning system existed except a conventional split unit for a special server room. Air
ventilation was and is done via manual window openings. The long back side of the office
building is oriented +236° (south is 0°) and several windows are equipped with external,
manually operated shading devices. Cold water is generated by an ammonia-water
absorption chiller and is distributed via chilled ceilings. Space heating occurs with those
same new installed ceiling elements and with existing radiators. Some technical installations
already existed in this building and were used in the new heating and cooling concept. Five
heat storages with 2 m³ volume each and heat generation devices like a condensing natural
gas boiler, three combined heat and power plants (CHP) powered by vegetable oil and
natural gas as well as a high temperature ground source heat pump were integrated in the
system.
Type of building Office building
Location Gleisdorf, Austria
In operation since 15.06.2010
System operated by Feistritzwerke
Air-conditioned area 1,000 m²
System used for space heating? Yes
System used for DHW preparation? Yes
General description of the system
Solar thermal energy is produced by a 64 m² collector field and is stored in five 2 m³ heat
storage tanks. One of these tanks is switched in series to the other four tanks and is working
as a high temperature tank, equipped with a stratifier unit and can be operated independent
of the other four tanks. They are switched in parallel to each other and are used to store
surplus heat generated by the solar collectors or the CHPs.
During the heating season the three CHP’s, the condensing natural gas boiler and the heat
pump serve as backup. Except the Feistritzwerke office building also a local district heating
net has to be supplied with heat.
The absorption chiller’s generator heat is taken out of the high temperature tank. The cold
water generated by the chiller is transported directly to the cold distribution system without
any cold water storage in order to avoid an extra cold water pump to reduce the electricity
effort. A dynamic cooling power control configuration is achieved for the chiller. The mass
flows and relevant temperatures of the particular hydraulic cycles of the chiller (generator-,
recooling- and cold water cycle) are varied in that way, that an infinitely variable control of the
produced cooling power is possible. Heat rejection of the absorption cooling process is
realised with an open, wet cooling tower combined with an electrolytic water preparation
device with the advantage of reduced electricity consumption.
Central air-conditioning unit
page 19