Commissioning: It’s in Your A5 Footprint – Here’s Why It Matters
May 8, 2026
By Jeremy Mansfield OAM, Mansfield Advisory Pty Ltd
Most people in the industry still see commissioning as nothing more than the final step where we prove the building actually works before handover. Run the systems, test them, sign off, and move on.
But under every major standard (EN 15978, NABERS Embodied Carbon, the national Embodied Carbon Measurement for Infrastructure - Technical Guidance, and Infrastructure Australia’s Embodied Carbon Projections for Australian Infrastructure and Buildings), commissioning energy and water use is formally part of the A5 construction process emissions. It is not optional. It is part of upfront embodied carbon.
What is Commissioning?
Infrastructure Australia defines commissioning energy in module A5 as:
“Commissioning is the stage in the project where an asset is tested – in whole or in part – before being handed over to the client. It occurs between construction completion and practical completion, though it is often staged for larger projects. Commissioning may continue following handover to the asset owner, however the commissioning energy included in module A5 contains only the work completed under the control of the constructor. Typically, commissioning includes the testing of critical systems, such as back-up electricity generators, security systems, fire systems, extractor fans and plant rooms. Commissioning energy is typically electricity, though significant amounts of diesel can often be used, particularly to test backup generators or in cases where commissioning is done when the project is still off-grid.”
EN 15978 is a European standard that provides a standardised, Life Cycle Assessment (LCA)-based calculation method for assessing the environmental performance of new and existing buildings. Glaringly, standard EN 15978 diagrams label A5 simply as “Construction and installation process”, with no explicit mention of commissioning. This visual simplification contributes to why the issue is so often overlooked. Even detailed guidance tables based on EN 15978 typically describe A5 as covering “installation of materials and products, ancillary materials, wastage and onsite transport”, with no explicit mention of commissioning energy or water use.
The New Australian Standard (AS 5342:2026)
The primary national framework for building commissioning is the recently published AS 5342:2026. Its purpose is to provide a consistent, systematic quality assurance framework for the commissioning process and related management activities. It focuses on process, documentation, roles and responsibilities, planning, verification and functional performance.
Notably, the standard does not address energy consumption, carbon emissions or water efficiency during the commissioning phase. Its scope is limited to functional and procedural consistency.
In contrast, NABERS Embodied Carbon provides dedicated rules and default values for construction and commissioning emissions in its rating methodology.
This is a glaring blind spot.
The Real-World Scale
On complex projects – hospitals, data centres, metro and tunnel works – the commissioning phase can easily run for months, sometimes six months or more. During that time, full HVAC, lighting, pumps, and temporary power are often left running 24/7. Not always because every system must be tested continuously, but because of scheduling, late BMS integration, or the long-standing assumption that “whatever needs to be used just has to be used.”
Commissioning rarely goes as planned. That is exactly why the industry has invested heavily in independent commissioning agents, the Soft Landings framework, and improved handover processes from Practical Completion to operations – to address the performance gaps that emerge after the keys are handed over. Yet these efforts almost entirely ignore the resource consumption during the commissioning window itself.
The same goes for water. Large-scale flushing, pressure testing, and system balancing can consume enormous volumes – yet this too is treated as an unavoidable functional necessity rather than a resource that can (and should) be managed more intelligently.
The Hidden Costs: Carbon, Water and Dollars
The result? Unnecessary carbon emissions and very real utility costs that sit inside A5 but are rarely properly accounted for. In practice, this shows up as full building lighting and HVAC left running 24/7 for weeks or even months during testing, repeated refrigerant re-charging because leaks go undetected or unaddressed, and water systems left flushing or running continuously for days during balancing and pressure testing.
For large, complex projects, energy consumption can be very significant. For example, Sydney Metro has 31 kilometres of tunnels and seven underground stations between Chatswood and Sydenham, fed by six substations that convert a 33,000-volt incoming supply from Ausgrid into lower voltages, including the 1500-volt DC used to power the electric trains. The tunnels and stations are ventilated by 72 large fans, which circulate fresh air.
Large-scale studies from Lawrence Berkeley National Laboratory (covering 1,500 North American buildings across three decades) show that proper commissioning typically delivers median energy savings of 13–16%, with median simple paybacks of 4.2 years for new buildings and 1.7 years for existing buildings. This directly reduces temporary power and utility costs for the contractor (improving their bottom line) while also lowering overall A5 construction carbon emissions.
Importantly, this is not about doing less commissioning. Thorough commissioning is essential for long-term building performance. Both too little and too much energy and water use during this phase can indicate poor commissioning practice, which often leads to higher operational emissions later.
Why This Matters Now
This isn’t just an environmental issue. It is also a very real utility cost and schedule issue that has gone largely unchecked for years.
Modern equipment adds another layer. A large portion of this plant is now IP-addressable or pre-programmed well before it is connected to the full BMS. In theory, this gives us new tools to manage energy and water more intelligently during commissioning – yet current commissioning plans and practices rarely take advantage of it.
We already know from the previous article that operational control A5 boundary reporting is the more accurate and comparable way to measure construction emissions. Commissioning is a perfect example of why that matters. Without clear direction from clients and proper data flow, this significant slice of A5 disappears from view.
Call to Action
If we’re serious about ASBEC’s 60–75% upfront embodied carbon reduction targets by 2035, what’s needed is clear, consistent guidance on how to integrate efficiency planning into the commissioning process from the very beginning. Commissioning well is still the goal; we don’t have to waste resources and dollars getting there. A quality outcome considers all issues and ensures that the right amount of effort, controls and performance is realised.
I’d genuinely value your thoughts on this, especially if you’ve seen long commissioning periods, unnecessary energy or water use, or missed opportunities on your own projects.
The more we talk about it, the harder it becomes for the industry to keep ignoring it.
