It was back in 2000 that an EU directive on the phaseout of HCFC refrigerants was passed. However, it's only now that the real impact of the controls is likely to be felt
by Andrew Keogh
12 January 2007
It has not been possible to purchase new air conditioning equipment that uses the HCFC refrigerants R22 since the end of 2003. Nevertheless an unknown, large number of existing air conditioning systems that use R22 are still in situ throughout the UK. The EU directive that mandated the phaseout of HCFC refrigerants was passed in 2000. One could be forgiven for assuming that, in 2007, its purpose had been fulfilled by now. However, the real impact of the directive is likely to be felt only in the coming few years. Hundreds of thousands of units installed on thousands of buildings all still require supplies of R22 for service and maintenance.
As well as prohibiting HCFC in new products, the directive also set a timetable for the eventual phaseout of R22 for servicing existing plant. To meet the requirements of the legislation, the quantity of R22 available will steadily reduce up to 2010.
Handling the change
So how should those responsible for the operation of building systems plan to handle these changes? The first step has to be to assess the magnitude of the task. This requires a thorough survey of the building's systems to determine what plant uses R22 - its age, state of repair, maintenance and reliability history, and the impact a possible failure might have on the business of the building's occupants.
The second step is to develop a plan for the plant's eventual replacement. For much of the installed base this will be a relatively straightforward decision as the equipment in question is probably already 10-15 years old. By the time the restriction on the use of new R22 takes effect this plant will be nearing the end of its anticipated economic life and can be replaced with a non-HCFC alternative. While no one likes spending money on something that has probably been taken for granted for the past 15 years, there are substantial potential benefits to be derived from the situation. New equipment is considerably more energy efficient than its predecessors and offers significant savings in running costs. It is also likely to be smaller, lighter and less noisy.
In most cases like-for-like replacement of plant cannot be advocated. It is highly likely that the building configuration, occupancy and usage patterns will have changed dramatically since the current equipment was installed. Step three in the replacement process should be a thorough review of operational demands to ensure that any new plant is appropriate to current and future needs and thus offers the maximum possible energy efficiency.
For those R22 units that will still have significant economic life left come 2010, it may though be prudent to plan to convert them to an alternative refrigerant sometime shortly thereafter. There are two principal alternative refrigerants: R407C and R417A. R407C is definitely not a drop-in, while R417A is claimed to be so.
Refrigerant choice has become much clearer in recent years and there are essentially two broad alternatives: an HFC such as R410A or R134A or 'natural' gases such as ammonia or propane. None offers a perfect solution so it's a question of compromise.
Ammonia has some excellent environmental credentials as it has no direct global warming potential (GWP). It has been extensively used for many years in industrial refrigeration, food processing and breweries. However, ammonia is highly toxic, concentrations of 0.5 per cent v/v can be rapidly fatal. It is also flammable at concentrations of between 15 to 28 per cent (v/v) in air. While the highly noxious smell of ammonia aids leak detection its extreme unpleasantness can also induce panic.
Propane also offers excellent environmental credentials as it has no direct GWP. Hydrocarbons have previously only been used in large industrial refrigeration systems and, more recently, in domestic refrigerators. However, such hydrocarbons have one principal disadvantage, their flammability/explosiveness (1 kg of hydrocarbon has the same explosive potential as 1 kg of TNT). The European standard EN378 already imposes limits on the use of ammonia and hydrocarbons in some types of buildings and systems.
Neither toxic nor flammable and as such there are very few limitations on the use of HFCs. However, if released into the atmosphere HFCs will contribute directly to global warming but today's systems are designed to ensure this never happens. And any impact on global warming is small compared to the release of CO2 during the production of the electricity required to run the plant, whatever the refrigerant used.
The magnitude of this indirect effect is determined by the energy efficiency of the plant and this tends to be broadly similar today for all refrigerant types. For these reasons, the best overall compromise is offered by the current HFC refrigerants.
Andrew Keogh is engineering
manager at Carrier Air Conditioning