Custom-designed cool HVAC system for Cummins

Print

By Pieter de Bod of WSP

The efficient building design for the new Cummins head office in Midrand includes several innovative and energy-saving technologies to conform to the company’s global image. 

Cover

Cummins is a global company that designs, manufactures, services, and distributes diesel and alternative fuel engines and power generation products as well as related components and technology. Cummins sells in approximately 190 countries and territories through a network of more than 600 company-owned and independent distributors and approximately 6 000 dealers.

In South Africa, Cummins took occupation of their brand new southern African regional head office facility in Midrand in December 2018. Located along the N1 highway in Waterfall City, this project deserves global appreciation and salute. The new large-scale facility comprises new head offices, servicing facility, master rebuild centre, training centre, an engine test cell, and a significant warehouse, as well as a planned generator testing facility.

Not only has the architect designed a beautiful, slick, and stylish architectural edifice, but they also managed to infuse the vision of Cummins Inc. into their designs: “Innovating for our customers to power their success”.

This project was completed in 18 months, from the first design meeting in July 2017 to the beneficial occupation in December 2018.

The sheer size of the new facility can be noticed when driving past it on the N1 highway, but the true large-scale facility can only really be appreciated when moving around inside the new engine testing and servicing facility.

The new state-of-the-art servicing area has a specialised mechanical ventilation system, which will allow Cummins to perform various technical tests on their engines.

The temperature inside the service area is very comfortable, even on a hot summer’s day. This is due to the roof of the servicing workshop being insulated and very high (approximately 19m), and due to natural cross ventilation through the huge doors on the sides of the building. Natural light floods the servicing area through vertical windows at low and high levels. Smoke is extracted from automatic ventilators and smoke extraction fans. Technicians repair and overhaul Cummins large diesel engines in this area.

Engine test cell

An advanced engine testing facility is constructed to perform various tests on Cummins’ engines. The test cell room is constructed to be explosion proof. Special glass and accessible doors are designed to ensure that an explosion inside the room is contained in the room. The test cell is designed to perform engine tests under controlled environmental conditions. When an engine is tested in the test cell, it is paramount that sufficient outside air is supplied into the cell because an extremely large amount of heat is generated by the engine itself.

A specialised extraction and make-up air system was designed by AConsult to cope with Cummins’ cooling and ventilation requirements of the test cell. Make-up air is conducted by two sets of vertical sheet metal ducting into the test cell room and positioned vertically in two corners of the room for the full height of the room. Filtered outside air is blown onto the engine with special 30-off directional industrial drum louvres, which is ideal for high air volumes and long throws. The exhaust from the engine is connected to an exhaust system to discharge the hot engine exhaust to outside.

Evapco cooling towers are located outside, and they are designed to reject the engine coolant heat to outside by connecting the test engine’s various cooling supply and return pipes to the external cooling towers. A separate control room is constructed adjacent to the test cell room with a viewing pane to monitor the activities in the test cell room. All the sensors are connected to a central computer to log and monitor the engine test. Special floor trenches in the room allow all auxiliary services to be routed neatly inside the trench. The floor trench is covered with galvanised mentis grating. Compressed air is also provided into the test cell.

Spray booth

The new Cummins facility includes a large spray booth, with a special integrated extraction system supplied by Aer-o-cure. Aer-o-cure specialises in the manufacture and installation of custom-designed, technologically advanced equipment for the refinishing industry.

Head office

The new head office workspace is air conditioned by a new three-pipe variable refrigerant volume (VRV) system and designed to optimise workflow and collaboration of occupants. The air conditioning and ventilation is innovative and not the standard design. On the surface it looks like a standard VRV system, but the design varies somewhat from the conventional VRV system.

The fresh air is pre-treated by means of a custom-built package unit to pre-filter, and pre-cool or pre-heat the fresh air. The main reason for this design strategy was to maintain a reasonable indoor temperature, even if the VRV units are not operational. Some of the indoor VRV units are linked to the occupancy sensors. Compared to a system where only filtered fresh air is introduced into the space, the effect of the pre-treated fresh air system on the VRV system is substantial and allows the capacity of the VRV system to reduce, which results in smaller indoor and outdoor units — the units are quieter. The VRV units supplement the cooling and heating required in each space and the insulated refrigerated pipework is smaller and reduced in size.

The Daikin VRV heat recovery system is an air-cooled direct expansion system with inverter heat recovery. The VRV system is a multiple in- and outdoor unit system and can simultaneously cool and heat various indoor units from the same system.

Hidden from sight, the VRV outdoor compressor units are located on the roof of the building, and refrigerant is reticulated to indoor units (located on office levels below) by means of insulated refrigerant piping system. The outdoor units incorporate inverter hermetically sealed scroll compressors operating on refrigerant R410a, and efficient inverter-controlled brushless DC motors driving the compressors, while DC motors drive the condenser fans.

The design team was able to upload multidisciplinary services on a live Revit model and design their individual systems to suit, as opposed to designing in two-dimensional plan views and coordinating services afterwards.

Hide-away, cassette, and wall-mounted indoor units are installed in the ceiling on each floor, and carefully zoned to serve the perimeter and internal zones. This arrangement allows for the correct thermal zoning of the building to prevent over cooling in one area with under cooling in another. A benefit of the VRV system is to allow for economical after-hours use of the air-conditioning system, when only certain departments may be working. Permanent hinged ceiling access panels or removable ceiling access panels are catered for in the office area below the indoor units for maintenance purposes.

Each VRV indoor unit contains the necessary washable removable (clip in/out) filters and filter box, fire-resistant insulation, cooling coil, and three-speed supply air fan — this is to provide economy of operation. Return air is to be drawn directly into the unit and mixed with a regulated amount of pre-treated outside air. VRV indoor units are installed with a formed insulated condensate drain pan and hose, and connected to the supply air grille or diffuser with a rubber connection or insulated flexible duct to eliminate possible vibration transmission. The condensate drip tray below the fan coil unit is connected to a condensate drain in the ceiling void at the fan coil unit.

Some individual offices (like corner offices), meeting rooms, focus areas, and boardrooms have dedicated controllers on the wall at approximately 1 400mm above finished floor level, which provide the occupant with control within a tolerance of ± 2.0°C of the design temperature, which is 22.5°C. The controller enables on/off switching, fan speed control, and temperature selection. The controller screen is backlit, and the text is large enough to read.

Cummins00 29Revit is used to model the HVAC design. The HVAC equipment that can be seen on the roof of the office building are: the Daikin VRV outdoor units, Eco Aire fresh air pre-treatment unit, canopy extraction fan, toilet extraction fans, and a small fresh air fan.
Image credit: WSP, Carin Morgans

The canteen

The canteen’s kitchen is equipped with a wall-mounted canopy with air-capturing technology. The stainless-steel canopy hoods with a capturing jet-stream device are installed in heavy cooking areas in the commercial kitchens to break down grease. The smoke capturing jet-stream device decreases the airflow, whilst increasing the smoke capturing efficiency and reducing the fan energy consumption. The induced jet stream minimises the heat and impurities produced by cooking appliances spreading to the work area. Compared to conventional exhaust-only hoods, this capture jet stream is claimed to be up to 23% more efficient.

External louvres are installed on the façade on the north and west orientation.

Cummins00 30

This picture shows all the HVAC components in the office building, using Revit. Notice the various duct runs, VRV indoor units, flexible connections and diffusers, and the HVAC equipment on the roof.
Image credit: WSP, Carin Morgans

HVAC monitoring

An intelligent touch manager is a VRV system controller with an array of simple and useful system management functions that give you ultimate control over the VRV air-conditioning network from an easy-to-use, programmable touch-screen interface. The intelligent touch manager allows controlling up to 64 indoor unit groups. This controller displays the floor plans that enable a quick search of the desired air-conditioning units in the Cummins building. A great advantage of this controller is the logging of operation history that shows the mode of control and the origin of past operations of air-conditioning units. Each indoor and outdoor unit is connected to a group controller, where the set points can be adjusted, to enable on/off switching, fan speed control, and temperature selection. The controller is located in a control room.

The VRV system allows good system flexibility in case of later office churn.

Revit and BIM

The professional team used Revit and building information modelling (BIM) to design this project. The design engineers and the architect used BIM from a design perspective and all coordination and clash detection was done using BIM.

The design team was able to upload multidisciplinary services on a live Revit model and design their individual systems to suit, as opposed to designing in two-dimensional plan views and coordinating services afterwards. The time saved from the design perspective is invaluable, as the design and coordination processes are amalgamated into one process. Architects, engineers, and professional team members are becoming more proficient and advanced with BIM as the implementation on projects increases.

List of professionals

Design team

Developer  - Zenprop and Attacq
Architect  - Empowered Spaces Architects
HVAC consultant - WSP
FIRE consultant - WSP
Electrical consultant - Quad Africa
Structural engineer - DG Consulting
Quantity surveyor - Schoombie Hartmann
HVAC contractor  - IES
Project manager - Capex Projects
Test cell ventilation - AConsult

HVAC equipment suppliers

Rooftop package unit - Eco Aire
VRV system  - Daikin
Fans - AMS
Grilles and louvres  - Advantage Air
Diffusers  - Rickard
Canopy  - Catervent
Canopy fire suppression  - Kidde
Paint booth - Aer-o-cure
Cooling towers - Evapco


Click here for the latest issue of RACA Journal