Industry seeks solution on pipework insulation

Tests conducted by a specialist refrigeration piping contractor have confirmed negligible energy benefits from using higher R-value – and thicker – insulation on refrigeration pipework for air conditioning systems. As a result, industry stakeholders are now calling for a revision of the relevant section of the National Construction Code (NCC) to address the issues associated with the excess insulation.

Currently, to comply with NCC 2019 clause J5.8(a), refrigeration pipework requires a layer of insulation up to R1.7 – up to 38mm thick. This has a number of implications including:

  • Increased labour costs – up to three workers are required to put the insulation in place, and it can take three times as long as installing thinner insulation
  • Damage to smaller diameter tube when putting the thicker insulation in place
  • The need for closer pipe support intervals to carry extra weight and prevent services from sagging
  • Fire rating concerns
  • Space constraints in ceilings and around equipment
  • Greater embodied energy required to produce, store and transport the thicker insulation.

All of this is reflected in inflated project costs. It is estimated that contract value for clients is increased by as much as 35 per cent.

Questions were raised when the insulation requirements were first introduced in NCC 2019, but until now, there has been no conclusive data about their effectiveness. To provide industry with that data, Ventrix commissioned Vipac Engineers & Scientists to conduct comparison testing between different insulation sizes covering the interconnecting pipework of an air conditioning system. The tests were designed with input from a range of industry stakeholders, and carried out in a NATA-certified facility in general accordance with AS/NZS 3823.1.1:2012 and Determination 2019.

They included a 7.1kW high-wall split system with a variable speed compressor and a 50m pipe run in a balanced ambient calorimeter chamber using 38mm, 32mm, 25mm, 19mm, 13mm and no insulation in both heating and cooling modes. The tests measured the impact of the different insulation thicknesses on energy efficiency, capacity and power input.

In cooling mode, the reduction in energy efficiency ratio (EER) between 38mm insulation and 13mm insulation was found to be 0.42 per cent.

In heating mode, the reduction in coefficient of performance (COP) between 38mm insulation and 13mm insulation was found to be 0.72 per cent.

Between all sizes of insulation in both heating and cooling, the differences were well within margins of error.

“These results speak for themselves and hopefully will be used to confidently to move the requirement to reasonable parameters,” says Ventrix owner Andrew Markopoulos.

Given the significant costs – environmental and financial – of using thicker insulation, and the minimal improvement in performance, there have been renewed calls to revise the provision.

The NCC can be revised during the usual update process, but the next version will not be adopted until 2025.

Another option would be for practitioners to use the test data to develop performance solutions. But for smaller projects, the cost of doing this would be prohibitive.

A final possibility would be for an out-of-cycle change to the code. Industry stakeholders are currently communicating with the Australian Building Codes Board (ABCB) to investigate this option.

In terms of how this will affect industry, Markopoulos says: “While this test has produced results that clearly back countless performance solutions in this area and prove the need to review the current NCC, I’m hoping the ABCB can use this example to justify funding to allow them to carry out more testing, where they as well as industry believe it necessary, to help alleviate future flaws in the Australian building code.”

More information on the test results is available directly from Andrew Markopoulos:

6 Replies to “Industry seeks solution on pipework insulation

  1. I certainly hope the same test conclusions are not applied to cool room and all pipe insulation projects.
    One of the main considerations in selecting wall thickness of insulation is to maintain the dew point inside the insulation for obvious reasons.
    The photo of the test chamber indicates that there would be air movement over the pipework. This movement helps to prevent surface condensation on the insulation. A ceiling or closed area installation would normally have no surface air movement allowing the dew point under humid conditions to move outside the insulation causing obvious condensation damage.
    Claiming “fire rating concerns” is not a valid point as pipe insulation for buildings is fire rated to 0 0 0 5
    One other advantage with higher wall thickness is to maintain lower discharge temperatures in the refrigeration circuit, ensuring longer compressor life.A quick check on the pressure enthalpy diagram will verify this.

    1. You obviously have never tried to insulate 1 1/8 pipe with 42mm thick inso. So until you try it for yourself up on a ladder I think you should pipe down…. 😉

  2. Be careful with the “fire rated” advice in your description there Bill. NCC Spec 7 requires a limit on smoke development and not all pipe insulation achieves that. Without the rating, it’s not not permitted in Class 2 to 9 buildings.
    Kembla highlight that the white PairCoil isn’t tested for this in their brochure, and there are plenty of projects out there with inadequately tested alternative imported products. This is an increasingly common item appearing in defect inspections.

    1. Thanks for the comment Brett. My comments are based on the assumption that only suitable fire rated insulation is being considered for such projects. It is readily available and has been for forty years in Australia.

  3. So, correct me if I’m wrong but current NCC requirements are eliminating the use of insulations below R1.7 on all chilled and heating HVAC lines? I did read another report where widespread noncompliance to this change has been reported across metro Melbourne sites.

  4. We have seen lots of performance solutions to prove 9mm, 13mm and 19mm insulation with NCC section J5.8. does meet insulation and fire index requirements. We believe these results show a good reflection and very helpful to better control costs and labour in applications. We agree the NCC should be changed for clarity.

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