commissioning

Commissioning & recommissioning buildings

An overlooked opportunity to improve building energy efficiency performance
Tuesday, December 5, 2017
by Jeremy Miles

Property owners and managers are placing increased focus on the energy efficiency performance of their buildings. This is often driven by a desire to reduce energy costs, or a focus on reducing energy consumption and associated emissions to achieve organizational sustainability and social responsibility goals.

One key area that should not be overlooked when evaluating building energy efficiency performance is control system commissioning and recommissioning. Properly commissioned control systems ensure that building equipment is operating efficiently, harmoniously and as intended. Without a continued focus on commissioning, efficiencies can be lost, energy can be wasted, costs can increase, and at worst, systems or equipment can work at cross-purposes. It is surprising how frequently even new buildings are not commissioned correctly. Even when buildings have been commissioned appropriately, over time there can be changes in building operations personnel, internal processes, or the way spaces and even entire floors are used – all of which are prudent reasons to periodically review the operation of control systems.

Today, most commercial, institutional, industrial, recreational and large scale multi-residential facilities have an element of building management controls in them. Building management systems (BMS) or building automation systems (BAS) have hard-wired or radio wave direct digital control (DDC) elements that are capable of a degree of control. These can be as simple as an ambient temperature sensor for a boiler system that anticipates heating or cooling demand based on exterior temperature. Alternatively, the components can be as complex as a combined heat power (CHP) unit that needs to match power generation wave form, voltage and demand while integrating with heating system thermal requirements. In more complex BMS it is crucial to have the correct operating parameters assigned to different elements to maximize system efficiency, avoid dangerous situations and minimize energy consumption.

All the individual DDC components are Internet Protocol (IP) accessible with unique identifier addresses, allowing automated remote control of systems. The BMS can control any system that has DDC mechanisms employed and can include setback parameters or program logic that anticipates required actions based on other parameters to maximize efficiencies. The control system software and hardware platform or communications protocol can be proprietary or open source. In a proprietary system, the equipment is operated under licence and usually requires the original equipment supplier to program or make any changes. In an open source scenario, you can add extra control points that may not have to match the original supplier’s protocol or which can be programmed to match various other protocols.

Building commissioning or recommissioning (recalibration) is the process of verifying the appropriate BMS control settings, validation of design assumptions and proving system capability at all stages of integration. The validation and verification of operating procedures will result in the optimization of overall system performance. A qualified commissioning agent or professional engineer should be engaged to review the existing system. Reprogramming and associated commissioning will ensure that the systems are working in harmony with each other, maximizing operating efficiencies by matching demand or facility requirements with appropriate levels of supplied energy. This could be associated with: lighting controls, fan speed, delivery volumes, temperature setpoints, firing rates, etc.

For example, if a chiller and heating systems aren’t properly commissioned, it is quite possible to have them fighting each other 24 hours a day and consuming far too much energy. I have personally encountered control settings for an air handling unit that caused the system to bring in 100 per cent fresh air at -20 C to counteract an overactive heating system. This resulted in 35 per cent excess energy consumption but was easily corrected. It is not unusual for both older and newer buildings to have BMS systems that are not programmed correctly or have components missing. Building operators may also not know how to access the BMS software controls.

If your facility employs variable frequency drive (VFD) or variable speed drive (VSD) motors for pumps or fans, the importance of correct system settings and the potential to save energy is even greater. VFDs allow for the ultimate match of the delivered volume of air or fluid heat or chilling capacity to meet demand, and can ramp up and down based on requirements. The DDC components may be triggered by temperature or pressure sensors or even pre-programmed hours of operation. More sophisticated buildings can monitor carbon monoxide levels to adjust the fresh air intake volume to match code requirements. These features are beneficial when programmed correctly but can be highly detrimental with improperly sequenced program logic.

The Canada Green Building Council (CaGBC) utilizes a building rating system based on Leadership in Energy & Environmental Design (LEED) criteria to give new and existing facilities an associated rating. Fundamental building systems commissioning for new buildings and recommissioning for existing buildings are compulsory prerequisites when obtaining specific LEED certification levels.

The importance of having a properly commissioned building cannot be overemphasized as a low-cost, high return endeavour that maximizes occupant comfort, energy efficiency and the bottom line. The digital control world is here to stay and we need to take advantage of the associated benefits.

 

Jeremy Miles, CEM, LEED is a senior energy analyst with ATCO. Jeremy leads ATCO’s commercial energy management services team which has conducted more than 754 facilities audits totaling over 2.5 million square metres of commercial facility space in Alberta. Learn more at atcoenergysense.com.

 

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