To alleviate the constant pressures of environmental consideration, US technology group Johnson Controls has developed a seven-step process for Central Plant Optimisation (CPO), which can deliver sustained energy savings of up to 60%.
Johnson Controls building efficiency Africa area GM Neil Cameron explains that heating, ventilation and air-conditioning (HVAC) systems are the main culprits in terms of a facility’s energy consumption, as these account for up to 45% to 55% of a building’s energy use.
Lighting is usually the primary focus when energy efficiency is considered, but this is a misconception among building owners, he says, as it only accounts for about 16% of a building’s energy use.
“Companies that want to go beyond harvesting the easy energy efficiency wins to achieve sustainable future energy efficiencies need to take a ‘whole building’ approach to CPO,” emphasises Cameron.
The first step of CPO is the design of system infrastructure, which considers new construction and design, as well as existing buildings. Design deficiencies must be addressed by upgrading system configurations, thereby adding variable-speed drives (VSDs) and automation. This will enable a plant to run at a higher level of efficiency over its entire life cycle, says Cameron.
The second step entails choosing the most suitable components that will perform efficiently in real-world operating conditions. Components sized for the worst-case scenario may not run effi- ciently in daily conditions.
It is also important to ensure that the chillers are pre-equipped with VSDs on the compressor, which will enable the chiller to operate efficiently under part-load conditions, Cameron adds.
The application of components is the third step. Cameron highlights that, to achieve peak performance, the HVAC systems must be applied and operated properly.
He states that building automation, which is the fourth step, is a prerequisite for optimisation. A building automation system (BAS) starts the right equipment at the right time to enhance efficiency, based on operational history and efficiency profiles.
It is essential for the BAS to incorporate a CPO algorithm to schedule the optimal number of chillers to operate under different load conditions.
Implementing networked optimisation software is the fifth step. The CPO algorithm forms the core of the operation that ties in with the BAS and holistically operates the plant in the most efficient manner.
The sixth step is maintenance. With the current ultra-efficient components of HVAC systems and optimised central plants, maintenance is more predictive. Performance data can be regularly measured, verified and managed over the plant’s entire life cycle, concludes Cameron.