Bosch’s head office backs its own product

By Ilana Koegelenberg

The new Bosch production facility and office building in Johannesburg boasts the company’s first commercial installation of its own variable refrigerant flow (VRF) system in Africa. 

This is the first construction project Bosch has undertaken since 1992. The all-new facility houses five different companies under the Bosch umbrella in one production facility. Based on the company’s long-term strategy, Bosch built a new three-storey production facility and office building in Kempton Park to house Hytec Holdings, Tectra, Hagglunds, Hysa-HAS, and Afripower under one roof.

The office building comprises three levels and a warehouse component; the gross area totalling 16 730m2.

Construction began at the end of March 2017 and was completed on time by the end of May 2018. Whilst working to a very tight programme, there were no delays in the delivery of the equipment.

The installation was completed with no problems and Bosch’s technical team from Turkey commissioned the systems without a hitch.

Going VRF

“The Bosch VRF system was successfully launched in Europe in 2016 and the decision to introduce it to the South African market was the obvious next step,” explains Yvette Bowden, business developer VRF, Robert Bosch. “Hopefully this will be the first of many installations of the product here.”

The Rexroth/Hytec Building boasts the continent’s first Bosch heat recovery VRF system, consisting of 12 outdoor units and 67 indoor units.

Office HVAC system

The industry-accepted ambient design conditions for this location are:

  • Summer ambient design: 30°C Dry Bulb (DB) / 20°C Wet Bulb (WB)
  • Winter ambient design: 2°C DB

The HVAC system for the Bosch building is as follows:

The typical expected HVAC design load for the building was designed at about 125W/m2 (summer cooling). The air-conditioning cooling load requirements are calculated using heat load calculation software to do an hourly analysis of the expected heat load.

Ducting was sized on the static regain and/or equal friction methods, as applicable.

A new VRF system — a Bosch Climate 5000 VRF RDCI Series with heat recovery technology — was installed to service the office component of the project. It’s an all DC inverter heat pump and includes ceiling cassette units for the meeting rooms and ducted hideaway units for the offices.

Two plant rooms are located on the roof level: one on the east side and another on the west side. Each plant has its own VRF condensers with six outdoor VRF condensers per plant (serving specific floors).

The outdoor compressor units are located on the roof of the building, and refrigerant is reticulated to indoor units by means of a refrigerant pipe system. The outdoor units incorporate inverters for hermetically sealed scroll compressors operating on R410A refrigerant. This means that if the load is reduced, the compressor speed reduces accordingly thus using less power. This type of compressor is also quieter and has lower starting currents.

Bosch0015Revit rendering of the ground floor training rooms and pause area.
Image credit: Aurecon


Bosch0016

Warehouse offices with split units Revit drawing.
Image credit: Aurecon

Fresh air ventilation

The offices are ventilated in accordance with the code SANS-10400 Part O “Lighting and Ventilation”. Fresh air design was for two air changes per hour or 7.5ℓ/s/person.

This ensures that an even distribution of fresh air throughout is achieved. There are two fresh air fans located on the roof, one serving the west side of the offices and the other the east side of the offices. Filtered fresh air is supplied to each office floor via a ducted system with take-offs to each indoor unit. The fresh air supplied to each indoor unit is balanced via a manual balancing damper.

Server room

The server is cooled by independent split units with a cooling capacity of approximately 7.5kW. As the user requires redundancy, two direct expansion units are provided to the server room. Each patch room is served by a 5kW direct expansion split type unit. The condensers are mounted on the roof slab above the server and patch rooms respectively.

Warehouse

Offices and select production areas within the warehouse are air conditioned with a series of direct expansion (DX) split type units. The condensers are located within the naturally ventilated warehouse, and the indoor evaporator units are within the offices’ ceiling void or wall mounted.

The facility is also ventilated in accordance with SANS-10400 Part O and is naturally ventilated by having a minimum of 5% of the floor area in an open louvre area around the building.

Air-conditioned spaces within the warehouse are mechanically supplied with filtered fresh air in compliance with the SANS code.

Various extraction systems are provided throughout the warehouse according to end-user requirements. This includes extraction for the following areas.

  • Hagglunds washing area: 700ℓ/s
  • Hagglunds manufacturing: 30 air changes per hour
  • Afripower welding bays: 2-off extraction arms
  • Afripower spray booth: ducting only for spray booth supplier to connect to
  • Afripower paint and paint mix store: to achieve 0.5m/s air velocity at low level
  • Afripower dark room: 30 air changes per hour
  • Afripower sandblasting: 30 air changes per hour
  • Afripower primer spray: extraction fan and ducting only, designed according to spray booth supplier requirements.

Toilet extraction

The public toilet and bathroom areas are ventilated following national standards. All public toilet areas are mechanically ventilated/extracted by means of extract air fans and ducting systems where natural ventilation is not possible. The discharge from the mechanical ventilation system is ducted to the outside and is vertically discharged with a venturi cowl.

In the end, everything came together on time and on budget, making a success of Bosch’s first local VRF project.

Each toilet block has its own dedicated toilet extract system complete with axial flow fan, sound attenuators, square ducting / spiral wound ducting, fire dampers (where required) and ceiling-mounted disc valves to ventilate the toilets at a rate of 50ℓ/s per toilet cubicle or urinal.

Noise control

The HVAC design solution only allows for sound attenuation measures normally associated with commercial-grade HVAC installations typically found in the building industry and complies with industry accepted norms and best practice engineering principles.

Items featured and covered include:

  • Sound attenuators on all axial flow fans on both sides of the fan (1.5D + Pod)
  • Proper sizing of weather louvres as well as air intakes and discharge vents.
  • Specification of equipment under the mechanical scope of works to be in accordance with the recommended noise ratings inside buildings (SANS 10103).

Reducing heat loads

Aurecon performed an energy analysis for various glass types using specific software. The different glass types were simulated and the results compared. The objective was to fine-tune and select the best performing glass type. The result was a glass type with a U-value of 1.91W/m².K and a glazing shading coefficient of 0.23.

The specified glass type reduced the heat loads by 25%. Therefore, the cooling capacity required from the units was reduced; thus, reducing equipment costs.

Challenges

Bosch VRF systems are relatively new within the local market. As mentioned, this installation was a first for Bosch locally and across the African continent. So, when the decision was made to use Bosch’s own VRF units, one of the biggest concerns and challenges was to ensure that the units arrived on time to meet the project’s tight deadlines, explains Ricky De Almeida of Aurecon, who handled the design of the project. “The units had to start arriving on site within two months, which was quite a challenge considering that they were being shipped internationally.

“Secondly, the units had to meet the design requirements and obviously be competitive with other brands already established locally,” he explains.

Bosch provided the assurance required and at the end of the day they delivered as promised. Bosch was also very helpful and professional regarding sizing and selecting the VRF system as per Aurecon’s design requirements.

In the end, everything came together on time and on budget, making a success of Bosch’s first local VRF project.

List of professionals

Owner   Bosch
Architect/designer  Empowered Spaces
Project manager   IBP
Consulting engineers Electrical Conscius
Mechanical Aurecon 
Wet services Empowered Spaces
Civil/structural  Kantey and Templer
Contractors  Main building Bantry 
HVAC&R Aircomfort 
Electrical  DC Electrical
Product suppliers VRF Bosch
Split units Bosch 

Click here to read the September 2018 issue of RACA Journal


 

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