Little known tricks that dramatically cut energy loss from pipework

You may have spent hours comparing the specifications of different boilers or air-conditioning units and weeks figuring out how to maximise your BREEAM score but is it possible that the true secrets to environmental sustainability lie outside a box ticking exercise?

Pipe insulation is a feature of any well designed mechanical system but, as the last component specified and installed its impact on the overall sustainability of a system is very limited. Installing more and more pipe insulation isn’t a way to viable way to fix mistakes made early in the system design process.

Minimise pipework to minimise energy loss from pipework

It sounds like the most obvious thing in the world but it’s ignored time and time again: every meter of pipework you can cut out of your system during the design phase is a meter of pipework that would otherwise be losing energy (regardless of how well insulated it may be).

Because of this the decision of exactly where you locate your plant equipment in relation to the radiators or your air handling units is of great importance. It’s actually likely that the energy lost from distribution pipework will be more heavily influenced by the location of the plant equipment than the pipe insulation material selected or the thickness installed.

Bring pipework indoors

When it’s cold outside the best way to conserve energy is to move indoors and the same is true for pipework.

The rate of heat loss from a pipe is directly influenced by the temperature gradient with the surrounding air, often referred to as the ‘delta-T’. As the ‘delta-T’ becomes greater the rate of energy loss increases dramatically. For heating pipes operating at 60°C the ‘delta-T’ indoors should never be greater than around 40°C but outdoors on a cold day the same pipe could be subject to a much greater ‘delta-T’, potentially 60°C or more.

Reducing the temperature differential by 50% directly reduces the heat flow by 50% so bringing your heating pipes in from the cold is something you should always consider before applying pipe insulation.

Turn the temperature down

Of course there’s another way to reduce the ‘delta-T’ – operate your heating system at a lower temperature. Historically heating systems had to operate at temperatures in the region of 75°C just to supply enough heat to the room to replace the heat lost through the building fabric but a long term trend in building service design has seen this change.

Since the revision of Building Regulations Part L in 2006 the higher standards of structural insulation have made heating systems with lower operating temperatures increasingly viable and increasingly popular. Today low temperature heating (LTH) utilising temperatures anywhere between 35°C and 55°C are the expectation for new builds.

A heating pipe operating at 45°C should have a ‘delta-T’ with the surrounding air of 20-25°C, meaning heat loss from the pipes will be less than half of what it would have been when attached to an older style heating system just a decade ago. And this is before pipe insulation is applied!

A little pipe insulation

Of course pipe insulation still has a role to play – even when the energy loss from pipework is reduced in other ways – but it’s important to assess that you get the right thickness.

Perhaps the best guidance currently out in the market is BS EN 12828:2012. This standard provides different recommendations on insulation thickness dependent on the operating conditions and location of the pipework. Compared with older guidance, BS EN 12828:2012 could actually recommend smaller pipe insulation thicknesses that scale in line with the energy saving expectation.