INTRODUCTION TO CONTINUOUS COMMISSIONING
Continuous commissioning is a relatively new concept, first introduced by the Energy Systems Laboratory at Texas A&M University, whom define it as “an ongoing process to resolve operating problems, improve comfort, optimise energy use and identify retrofits for existing commercial and institutional buildings and central plant facilities”.
Over recent years, there has been greater adoption and case studies generally imply potential energy savings averaging between 11-20%. With the ever increasing concern for reducing energy consumption, particularly within the built environment, continuous commissioning can be a significant to improving energy efficiency within buildings, whilst also addressing other building performance factors.
THE CASE FOR CONTINUOUS COMMISSIONING
Building performance is a major concern in the modern age, which is understandable, considering that energy consumption, maintenance and repairs typically account for over half of a building’s operating costs, with approximately 30% from energy consumption, alone.
Although most new construction projects undergo a commissioning process, it is often initiated late in the project development and ceases at project handover – often with systems only partially commissioned, thus the full benefit of commissioning is rarely realised. This is then followed by a change in use in spaces and load demand from the initial design intent. Hence, even a well-commissioned building may be inefficient when put into use. Over time, buildings and the installed services also dilapidate, leading to reduced performance and increased energy consumption in deteriorating systems.
These issues can all be mitigated to some extent by implementing a continuous commissioning regime, in that the continuous monitoring, verification and adjustment of the installed services can lead to identification of performance deficiencies, operational problems and design inefficiencies, as well as fine-tuning systems to reduce the impact of any identified issues and optimise performance progressively.
BENEFITS OF CONTINUOUS COMMISSIONING
The most obvious benefit of continuous commissioning is reduced energy costs from reducing system waste and optimising system sequences of operation to decrease operating times on high-energy consuming plant and equipment. However, there are also benefits which are often overlooked, such as:
Improved thermal comfort;
Reduced maintenance costs;
Legislative compliance;
Increased plant lifespan;
Improved end-user experience.
COMPOSITION OF A CONTINUOUS COMMISSIONING REGIME
Continuous commissioning typically consists of a 2 phase cycle, the first being a needs assessment and the second, and implementation of optimisation measures. Throughout the process, data collection and analytics is the key element. The activities associated with each phase are identified below.
NEEDS ASSESSMENT
Continuous commissioning is a data-driven process involving careful, expert analysis of performance data and with the emergence of the Internet of Things (IoT), data can be captured in real time, enabling more accurate assessment of load demands and use of systems.
In addition to data from sensors and control systems, on-site measurement and verification of the installed services is essential, which when coupled with fault finding and troubleshooting, can provide a comprehensive overview of building performance in comparison with the actual needs of the end-user. This data can then be used to determine the baseline parameters and benchmark performance.
OPTIMISATION
Once the baseline performance has been identified, optimisation measures and desired outcomes can be identified. The needs assessment may identify retro-fits or installation of additional components to improve performance. However, the focus of the continuous commissioning shall be on optimising operation of the existing installations by adjusting set-points, sequence of operation, re-balancing air and water systems.
Some of the most common services which can benefit from optimisation are:
Air distribution systems;
Heating systems;
Cooling systems;
Water supply systems.
CONCLUSION
Continuous commissioning is rarely considered when building operators are looking to reduce energy costs or improve the indoor environment, with the rise of ESCOs in recent years promoting high savings from energy retro-fit projects. However, these are capital intensive projects – even with the flexible payment plans, whereas, continuous commissioning can be a more cost-effective solution to gain efficiencies and reduce operating costs.