It can be critical to the overall performance of a heating system but many consultants are unaware of exactly how pipe insulation works or how to maximise their energy saving potential.
Pipe insulation certainly reduces heat transfer from a pipe into the surrounding environment but there are a few factors that can dramatically influence just how much energy is lost.
Isn’t it just a matter of thermal conductivity?
Thermal conductivity (also known as the λ-value) is a useful value when comparing pipe insulation materials and we need it to make heat loss calculations but it’s importance is often overstated.
On its own the thermal conductivity can’t actually give you an indication of how much energy is lost from a pipe. Even a big difference in thermal conductivity values between two materials doesn’t necessarily mean that the heat transfer through those materials will vary greatly.
Increasing the thickness of an insulation material has a similar effect to reducing the thermal conductivity. Again a major difference in thickness doesn’t necessarily mean that you’ll see a major difference in energy saving.
So what things do matter?
Temperature differentials
The difference between the operating temperature of a pipe and the surrounding ambient is, hugely important. Pipework operating at 60°C in a 20°C ambient will lose far more energy than pipework operating at 50°C. There’s simply a far shallower temperature gradient and this means that energy is transferred out of the pipe at a slower rate.
Operating times
A heating system in use for 24 hours a day, 365 days a year will benefit far more from pipe insulation than a system which is in use only occasionally. This is because there is far more energy being used and, therefore, a much greater energy saving potential.
Harnessing “useful” energy loss
Not all heat loss from pipework is necessarily wasted energy if it’s being used to help heat a building. In practice how effectively this heat loss is able to contribute towards the heating of a building is directly related to the levels of structural insulation applied. Heat lost from pipework outdoors is obviously 100% waste but heat lost from pipework inside a house insulated to modern standards will be almost 100% retained – which can make it hard to justify any pipe insulation at all.
What’s the common factor?
Put together these offer a story about energy loss from pipework. In practice the actual energy saved by insulating pipework has little to do with the insulation material selected or even the thickness – it’s the properties, location and usage patterns of the heating system itself that matter most.
Applying pipe insulation to an inefficient heating system will prevent heat loss but, in order to select the right material and an optimal thickness, it’s essential to consider it at the same time as the heating system itself is being designed. Which is why standards on heating system design like BS EN 12828:2012 are increasingly making recommendations on pipe insulation.
Source: Kaimann UK · Copyright image:xxxx