Commissionability review, services and maintainability report (S&M), commissioning-focused design review – whatever you want to call it, it’s one of the most critical stages in setting a project up for commissioning success.
It’s the opportunity to put the building services design under the microscope before construction begins, checking whether systems can be commissioned, operated and maintained as intended. More importantly, it’s the most cost-effective time to identify potential commissioning problems, omissions or concerns with the design.
After all, it’s much quicker and simpler to update a few drawings or functional descriptions in the cloud than to change something on site.
What does a commissionability review look for?
The review considers whether the building services’ design provides what’s needed to test, commission, operate and maintain systems effectively.
Design details that can cause problems if overlooked
Pipework, ductwork and balancing
The usual suspects include:
- pipe and ductwork sizing and selections
- allocation, sizing and positioning of commissioning valves and flow measurement devices
- inclusion of branch dampers for proportional balancing
- straight ductwork runs for flow measurement devices or Pitot traverse locations
- pre-commissioning flushing and cleaning bypass provisions
- additional double regulating valves (DRVs) for simulating design pressure drops on future connection loops
- large diameter drain valves for backflushing heat exchangers and coils
- air vents, strainers, dirt separators and dirt pockets.
Installation and equipment protection
All that pipework needs to be anchored but allowed to thermally expand in a controlled way across its working-temperature (or ambient) range. It also needs to be seismically restrained and thermally insulated.
Sensor pockets must be provided, flow meters need straight pipe lengths upstream and downstream, and isolation valves are needed for future maintenance and eventual replacement activities.
Pumps need suitable curves for efficient operation in variable-volume systems. And those impellers need protection from debris, particulates and low-static conditions.
Plant selection, access and safety
Depending on the stage of design and level of detail available, a commissionability review can also uncover concerns around plant selection, layouts, accessibility and safety.
These include:
- proposed plant selections and layouts
- plantroom safety considerations, including door opening direction, refrigerant leak detection, ventilation provisions, override and alarm controls and pressure relief valve discharge locations
- component accessibility and tube withdrawal space
- plant replacement strategies, including equipment weights, dimensions and access pathways
- egress routes, fire separation and acoustic implications.
Controls and system operation
Systems need to be controlled, modulated and monitored. They must perform reliably under a wide range of operating loads and conditions, start up reliably, shut down consistently and stage up and down without tripping.
This is where a review can raise some important questions:
- Why is there no minimum flow bypass included?
- The chiller selection won’t work when the condenser water is below 15°C. Where’s the cooling tower bypass loop? Or, will you personally guarantee it will never, ever get that cold?
- How will the cooling towers be staged on and off. Are there sufficient motorised valves to achieve this?
- Why is there no cooling-tower water-treatment provision?
These are the sorts of questions you want answered while the design is still on paper, not when the commissioning team is standing in the plant room.
Getting it right before construction
Late changes kill project timelines, budgets and the best-laid commissioning plans. That’s why it’s vital to resolve any design oversights or control deficiencies identified by the big red pen before the construction documentation is finalised and issued.
Up to this point, changes are relatively easy to enact and can improve commissioning outcomes as well as the operability, maintainability, safety and energy efficiency of the completed building services systems.
The commissionability review stage is the first and best opportunity to resolve potential design or control strategy concerns before construction activities literally set them in stone, steel, copper or galvanised metal. In this instance, the big red pen is mightier than the hammer. And it can save your project time and money.
Involving the right specialist commissioning engineers at this stage gives the project team an opportunity to identify and resolve issues before they become more difficult and expensive to address.
