A large Australian installer of refrigeration and air conditioning pipework is conducting tests to determine whether certain insulation provisions in the National Construction Code (NCC) could be revised to facilitate installation of refrigeration pipework without affecting energy efficiency.
The provision in question in NCC 2019 is J5.8(a), specifically relating to insulation required on refrigeration pipework. The clause notes that for pipework containing a heating or cooling fluid, where the fluid is held at a heated or cooled temperature, a table of R-values apply. This often means installing a thick layer of insulation – up to 38mm.
Pipework installation specialist Ventrix has organised the test. According to owner Andrew Markopoulos, the current insulation requirements present a raft of issues.
“Up to three workers are required to insulate tube at the 32/38mm wall thickness end of the scale,” he says. “It also takes about three times as long to install.”
Other issues include damage to smaller diameter tube, the need for closer pipe support intervals to carry extra weight and prevent services from sagging, fire rating concerns, and greater embodied energy required to produce, store and transport the thicker insulation.
“But the most frustrating thing,” Markopoulos says, “is having to justify the extra 18–35 per cent increase in contract value to clients.”
A question of efficiency
The underlying question that Ventrix is seeking to answer with its testing is whether the extra thickness of insulation actually makes a difference to system performance.
“Over the past 10 years or so, we’ve been asked to increase the thickness of insulation on refrigeration-based pipework,” says Markopoulos. “It’s related to energy efficiency, but we started questioning a couple of things.
“While I completely agree that a chiller, boiler, AHU or FCU that has worked hard to produce an expected fluid temperature would appreciate its work is carried to its destination without loss of its held temperature, refrigerant gas is not the same as heated or chilled air or water. As a medium it should be treated differently.”
Certified testing
The tests have been conducted at a NATA-certified facility and designed with input from experts and industry stakeholders. They include a 7.1kW high-wall split system with a 50m pipe run in a balanced ambient calorimeter chamber using 38mm, 32mm, 25mm, 19mm, 13mm and no insulation in both heating and cooling to AS/NZS3823.1.1. The tests will measure the impact of these different insulation thicknesses on energy efficiency, capacity and power input.
Ventrix has covered the significant costs of the exercise, convinced that if the results lead to a change of rules, it would be a benefit not just for the company, but for the entire industry.
“I feel the difference in energy consumption between insulation thicknesses varying from 13–38mm in a refrigerant-based system would be quite minimal,” says Markopoulos.
“We are hoping the tests results confirm there is very minimal gain, if any, in increasing insulation thicknesses on refrigerant-based pipe. There are many people across the industry that would benefit from a positive outcome – and a revision of the provisions in the NCC to reflect this.”
One only has to do the thermal calculations to confirm that the thicker the insulation, the less the heat loss.
energy= area X U X TD reduce the U factor (increased wall thickness) and you reduce the energy loss BASIC PHYSICS
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