The extensive facilities at KPMG comprise individual and open-plan offices on the second to the sixth floor, a canteen with kitchen on the first floor and permanent cooling for the server rooms on the second, fourth, fifth and the top floor. The offices and canteen are supplied by the lines of five separate VRF 2-pipe systems. When it comes to the server rooms in particular, best practice applies: Five fully independent 1:1 split RAV systems provide perfect operating temperatures with maximum reliability to protect sensitive IT equipment – incorporated into the overall system’s controller which is expertly managed by TOSHIBA’s Smart Manager. In addition to maintaining a full overview of all system components and many advanced energy-saving functions, this tried and tested central remote controller provides access to all system parameters at all times – including via your browser from anywhere in the world. Given that the system can be individually configured via 68 wired remote controls, as is the case at KPMG, management often want wide-ranging timer or limitation functions and set-back options which prevent the set temperatures from being exceeded or not fulfilled in heating or cooling mode. Finally, in a building this size, every degree above or below that for an acceptable, healthy indoor environment has a noticeable impact on electricity bills over the course of a year.
Stefan Sekulic, Managing Director of TOSHIBA partner H&B Tögel Kälte-Klima-Service GmbH, who was commissioned to install the system, said that “the installation came with a few challenges”. There can be no doubt that having largely invisible & quiet systems is extremely important in Alsergrund, the ninth district of Vienna. H&B Tögel developed the perfect installation solution for the planners, ALL-PROJEKT Technisches Büro GmbH: The outdoor units are positioned in a partial opening in the roof truss lowered under the ridge edge – resulting in dramatic noise reduction of what are already very quiet VRF devices, without impacting on the sensitive Vienna roofscape.
A great deal of consideration was also given to passive safety, in the form of a leak detection system. Even though leakage of the R410A refrigerant is very unlikely (provided installation was carried out correctly), this system offers preventative protection. TOSHIBA offers two different solutions here: The smaller system goes by the name LD1 and mainly provides for compliance and conforms to EN378: If the total permissible quantity of refrigerant in very small rooms is exceeded (for R410A, this is the product of the limit value 0.44 kg/m3 and the volume of the smallest room), the standard calls for either additional ventilation in the rooms in question or the use of a leak detection system. In the event of a leak, a sensor at ground level detects the escaping refrigerant, generates a visual and acoustic alarm signal and stops the indoor unit. The affected indoor unit can also be isolated from the refrigeration circuit by means of motorized shut-off valves, as an optional feature. This facilitates rapid repair and recommissioning, without affecting other system components.
The LD2 system installed at KPMG goes a step further: All rooms are fitted with a total of 32 leak detection sensors – in the event of a leak, the control unit closes off the main line on the outdoor unit via motorized valves – the refrigerant is then drawn back out of the entire refrigeration circuit into the outdoor unit.
All in all, an attractive solution was created for the KPMG contractors, in which the general benefits of VRF direct expansion systems and the specific advantages of TOSHIBA components really come into their own: Maximum flexibility in terms of selection, combination and installation – the ultimate in user and operating convenience – the best energy efficiency values in heating and cooling mode, even in the case of highly divergent pipe runs.