By Pieter de Bod (Pr. Eng.)
WSP has designed a suitably ultra-modern displacement ventilation HVAC system for the new Kansai Plascon chemical laboratory in Krugersdorp.
Kansai Plascon has a reputation for innovation and quality, supported throughout the media with its print and television adverts. WSP identifies with Plascon’s core values of innovation and
About the author
|Pieter de Bod (Pr. Eng.) is an accredited Green Star Professional and works as the technical director of WSP Group Africa. He is a member of the American Society of Heating, Refrigeration and Airconditioning Engineers (ASHRAE).|
quality, and therefore designed a suitable ultra-modern displacement ventilation system, which is an energy-saving, high efficiency, and environmentally friendly HVAC system.
The new chemical laboratory for Plascon is located in Luipaardsvlei (Krugersdorp). The history of the Plascon brand stretches back more than a century to 1889, when an enterprising young Welshman named Herbert Evans arrived in Johannesburg and began producing floor polish, carriage varnish, and ready-mixed tinted paints — a first for the country.
In the ensuing years, Herbert Evans & Co. expanded rapidly, developing a reputation for innovation, quality, and customer service.
Today, Plascon continues to drive innovation and excellence in the retail, trade, industrial and furniture coatings markets in both South Africa and southern Africa, from three strategically placed manufacturing sites in Mobeni, KwaZulu-Natal; Luipaardsvlei in Krugersdorp; and Epping in Cape Town.
In 2012, the company, formerly known as Plascon South Africa, was renamed Kansai Plascon after a merger with Japanese company Kansai Paint, the world’s sixth largest coatings company. Kansai Plascon continues to champion the Plascon brand as it expands into Africa as the continent’s number one coatings company.
The air-conditioning and ventilation system for a modern-day laboratory like this corresponds well with international trends, especially the displacement ventilation principle on which this design is based.
This new facility consists of 28 laboratory benches (each with built-in air supply and extract air), two fume cupboards, a climate room that can simulate any weather condition from 5°C to 35°C and 15% RH to 95% RH, a constant temperature and humidity room, modern offices, upper class conference facility, kitchens, patch rooms, and various stores.
This new facility consists of 28 laboratory benches (each with built-in air supply and extract air).
Laboratory benches’ integrated air-conditioning design
WSP spent numerous hours on the design of the laboratory bench that provides an integrated high-class workbench for the research and development staff. Each bench has an integrated air extraction system that extracts at bench level. Supply air flows from the bottom of each bench. We specifically don’t refer to air ‘blowing’ out, but rather to air ‘flowing’ out at a very low velocity to prevent any air turbulence.
The air is supplied at a temperate of 18°C in cooling mode and 26°C in heating mode. Providing warm air at the lowest in a room is the most energy efficient, due to the natural tendency of warm air to rise and heat the room. Cold air at 18°C is not supplied at a lower temperature to prevent the risk of cold-feet-syndrome, and to benefit from the energy saving feature of direct free cooling when the ambient is 18°C or less. The supply air is provided to each bench by beams in insulated ducting. The laboratory is under a slight negative pressure compared to the balance of the building, and supply and extract rates are fixed to ensure a steady state air balance in the laboratory area.
The laboratory air distribution principle is a displacement ventilation system. Supply air is ducted from air handling units (AHUs) to each laboratory, and air is discharged at a very low velocity at the bottom of the bench. Airflow and temperature is carefully regulated in the AHU. Special co-ordination meetings with the architect, ProjectWorks, and the bench manufacturer were required to ensure the optimal functionality of the practical side of things.
Displacement ventilation systems are quieter than conventional overhead systems, with far better ventilation efficiency and enhanced indoor air quality. Displacement ventilation systems are appropriate in spaces where high ventilation is required, such as laboratories, classrooms, conference rooms, offices, and airports. The big benefit of displacement ventilation is the superior indoor air quality achieved by exhausting contaminated air from the room at high level and through the fume hood. Better air quality is achieved when the pollution source is also a heat source, like in some of the experiments.
Two-off high-performance fume cupboards reduce energy consumption and maintain or improve containment over standard models by fine-tuning the hood’s aspect ratios, airflow patterns, and controls.
The central ducted extraction system was designed to maintain a constant air extraction volume no matter where the hood sash is positioned. Face velocities will vary depending on where the sash is set and will increase as the sash is closed. Air bypass openings situated near the sash ensure that changes in face velocity are kept within a specified range. Special exhaust fans and ducting were used to ensure robustness against high corrosion or contaminated airborne particles and to provide a system with a lifespan of 20 years.
A special standalone air-conditioning unit was developed with a local company to cater for temperature and humidity conditions from 5°C to 35°C and 15% RH to 95% RH. Scientists at Plascon have to test products that are exposed to a wide range of weather conditions. In other words, weather conditions of almost any town in the country can be simulated, like a very humid Durban condition, or a cold, dry Sutherland condition.
Constant temperature room
A close-control air-conditioning unit was designed to maintain a constant temperature and humidity condition, and also for research and testing of paint products.
The office area is served by variable volume AHUs and variable air volume diffusers.
The major challenge on this project was the need for exposed ducting.
The major challenge on this project was the need for exposed ducting. Having exposed ducting requires ultra-neat installations, co-ordination of duct brackets with other services and the ceiling, as well as co-ordination of control and power cables and quality of the join details in the ductworks.
Another challenge for especially the contractor was to fine-tune and commission the HVAC system to ensure that design parameters were achieved. Temperature loggers were used to carefully monitor the various internal space temperatures in various ambient climate conditions and the results were meticulously trended and reported. Special attention was given to the air balance in the lab areas.
During the design stage, the energy consumption of the HVAC system and the air balancing of the various spaces relative to each other was tended to for compliance with the various indoor environmental quality (IEQ) standards.
Cooling and heating is generated by two air-cooled heat pump chillers, and chilled and hot water is distributed to various AHUs and fan coil units (FCUs) in the facility.
Last year we published an interesting pie graph that illustrates that the success of scientists and lab technicians is heavily dependent on a functional and well-equipped lab environment infrastructure like the HVAC system, because they spend most of their day in the laboratory testing new and existing products and processes. They require a pleasant working environment for optimal comfort and job functionality. It was therefore crucial that this new facility had a fully functional HVAC system.
Figure 1 illustrates how researchers spend their day, based on an eight-hour day, as per the BD&C/RICS Laboratory Users Survey, September 2003. It is therefore essential that the laboratory environment is pleasant and safe.
Except for the climatic and constant temperature rooms, this facility does not have any resistance heating. The AHUs are programmed to use economy cycle mode when the ambient temperature is favourable, saving energy and boosting outside air ventilation.
As with any other project, a sufficient amount of balancing devices were installed to make the balancing and commissioning phase of the water system fairly simple, allowing the HVAC system to run efficiently.
The lifespan of HVAC equipment is prolonged provided the system is frequently serviced and maintained (without skipping services) by reputable trained technicians according to the stringent service requirements of suppliers and council standards.
WSP prides itself on its ability to get involved in ventures like the new Kansai Plascon laboratory project in Krugersdorp, using the displacement ventilation system.