The most important aspect to consider nowadays when designing a system or a building services installation is that of energy consumption and efficiency. By Graeme Fox, technical committee chair, AREA
The biggest contributor worldwide to greenhouse gas emissions is power consumption in buildings. Excessive power consumed at home or at your place of work means that the power stations need to work that much harder to make sure the power supply is maintained. This is where the vast majority of emissions come from – power stations burning fossil fuels. So it is vital to make sure your designed system is maximising the energy efficiency.
To this end, engineers consider the Total Equivalent Warming Impact or TEWI, of a system. This takes into account the GWP, the energy efficiency and life cycle costs of running the equipment. Yet a number of organisations involved in the debate about what refrigerant is right for what application seem to dismiss these figures and concentrate solely on the GWP.
I would absolutely agree that many of the HFCs that I would endorse using have a relatively high Global Warming Potential compared to certain other refrigerants but concentrating on this figure is simply unscientific and blinds people to the big picture.
The F-Gas Regulation came into effect last July. Sadly the implementation of this only became law earlier this month and it will take up to two years until we have a fully compliant workforce across the UK. This Regulation will have an enormous effect on leakage rates in our industry, assuming the Government gives industry the teeth to implement and police the Regulation properly. The evidence for this has been shown in Holland where a strictly enforced mandatory registration scheme introduced some 16 years ago saw a massive drop in leakage rates.
The F-Gas Regulation (EC842-2006)
- Designed to minimise refrigerant and fluorinated gas emmissions to atmosphere
- Leakage rates dropped from around 20 per cent to less than 1 per cent
- Negligible leakage rates mean GWP is irrelevant
As an industry we have been jumping through hoops recently to raise standards, reduce leakage rates and generally improve our record with regard to the environment – not an easy task in such a diverse and fragmented industry, but one we are slowly getting to grips with.
The point here is that, assuming the F-Gas Regulation works – and I see no reason to believe it won’t – then the direct emissions of HFCs to atmosphere will be negligible or near to zero.
This makes the GWP largely irrelevant – the potential is only realised or becomes relevant if a refrigerant is released into the atmosphere.
The heart of the matter
Now to the nitty gritty.We have dismissed the GWP as an irrelevance from our calculations based on the realisation that the gases are not being released to atmosphere. Now we can concentrate on the really important task - determining which refrigerant is best for which application based solely on the energy efficiency achievable for each gas in its own right. Because this is where the tricky bit comes in.
I absolutely agree that in some cases CO2 is the best refrigerant of choice. Similarly in some cases Ammonia or Hydrocarbons may be the best refrigerant of choice. But our industry cannot simply produce a ‘one size fits all’ solution here. There is simply no such thing as one refrigerant being the answer in all applications.
For large deep freeze applications I have seen some wonderful ammonia systems, for large central plant systems I have seen fantastic evidence of where CO2 is working very well and with excellent efficiencies. Small household refrigerators and point of sale display cabinets, I understand work best when operating with Hydrocarbons. I visited the new Oslo airport ground source heat pump installation a few years ago and saw a large ammonia system controlling the temperature throughout the entire terminal building with excellent results.
But what about the huge range of medium to high temperature, medium duty systems serving our shops, offices, small server rooms and even our homes? What about the 10kW heat pumps being installed domestically across Europe in an ever expanding market? – especially now that the EC has finally accepted that they are a viable renewable technology. These systems play an enormous part in our lives and they absolutely rely on HFCs at the moment to keep running efficiently. As far as I’m aware there are no suitable alternative systems on the market that run on anything other than HFCs. The big question though is: Are HFCs the best choice in these cases of small to medium applications?
It is obvious that the air conditioning manufacturers will have been testing various alternatives in their equipment, but the difficulty we have as contractors here is garnering that kind of information to help us to keep our customers informed and help inform Government of the best way forward to help them achieve their ambitious emission targets.
I did, however, recently receive exactly this sort of information. It relates to a study carried out by the Japanese Refrigeration and Air Conditioning Association which consisted of testing a 4kW room air conditioner and a 14kW air conditioner which would normally run on R410a but was tested with various alternative gases, after some alterations to allow for obvious issues like pressure drops and heat exchanger sizes.
Taking R410a as the baseline, and therefore 100 per cent of the energy used, in the 4kW system the HFO1234y uses 67 per cent more energy to operate. Even the R290 is using 33 per cent more – and both of these have all the problems of flammability, which of course raises issues for contractors on health and safety grounds and massive increases in liability insurance.
So you can see that an enormous amount of additional energy is required to achieve the same cooling duty as with a standard system running on R410a – and that is before we even consider the additional costs incurred with insurance, training and manpower.
What about R32?, you may ask. Well, okay it uses 97 per cent of the energy compared with R410a, so it’s slightly better simply in terms of energy. However, I understand it is also highly flammable and more suited to applications where charged amounts are very small – similar to the other two I’ve just mentioned.
So it is clear that for the smaller range of split air conditioners the HFC is the winner in terms of energy efficiency. But what happens when we look at the larger units in this range – the 12.5 to 14 kW systems? The HFO1234 performs slightly better but is still using a massive 58 per cent more energy to run. And the R290 is actually worse at 34 per cent more energy.
Again the R32 performs slightly best of them all but by nature of the increased duty of the cooling unit we are talking about a proportional increase in refrigerant charge and with that the increased risk of catastrophic explosion.
The right refrigerant
So what does this tell us? It is clear to me that the right refrigerant to use is very much dependent on a large number of factors that all need to be taken into account to make systems as efficient as possible. Unfortunately there is no simple formula we can use to determine this. And no one body is able to definitively state the case because so many of them seem to have an axe to grind against another body or they have commercial interests that make their argument untenable to others.
Hopefully people can see that in AREA we do not have any particular slant towards any refrigerant. The Air Conditioning and Refrigeration European Contractors’ Association represents 21 member associations from 19 European countries representing over 10,000 companies and some 125,000 engineers - but, importantly, we represent contractors: from the large multi-national contractors working in large supermarket applications to the one man bands working on domestic refrigerators and split system air conditioners. From the western isles of Scotland all the way down to Turkey and everywhere in between. So, interestingly for this argument, I believe we can truly speak on behalf of all the various factions within our industry. And we can truly say that we have vast experience available to us with regard to all the various alternatives that we will hear about later today.
Air conditioning and Refrigeration European contractors’ Association
- 21 Member Associations from 19 Countries
- 10,000 contractor companies
- 125,000 engineers represented
AREA does fully support the principles behind the EC’s Copenhagen summit position paper, but we have grave concerns over the throw away comment that seems to suggest an intolerant view of HFCs and basically states they are not sustainable in the long term. The basis for their argument is that the enhanced phase out of HCFCs will lead to a direct increase in the use and volume of HFCs.
But they do not take into account several factors: HFC charge volume is considerably less than their HCFC counterparts for the same cooling duty - so a like-for-like swap out of an R22 system with an R410a system, for example, would result in a considerably reduced quantity of refrigerant on that site; the F Gas Regulation that I’ve already mentioned will have an enormous effect on the amount of refrigerant directly leaked to atmosphere; and, as I’ve just demonstrated, the HFC plant will use considerably less energy for some applications than their lower GWP alternatives. So surely for the type of application I’ve outlined, where energy consumption is shown to be so much less when using the standard R410a refrigerant, the HFC is clearly the best option here in terms of energy efficiency. It is clearly the best choice in terms of energy consumed. It is also, therefore, clearly the best choice for the environment as the emissions will be far less in providing the power for this plant than they would be if HFCs were banned and the manufacturers had to supply this equipment to run on one of the alternatives shown.
We need to keep a clear, open mind when considering all the options and not get blinkered by political dogma or misleading headline grabbing soundbites by professional lobbying organisations.
We are all concerned about climate change and its effects. But we have to remember to keep a perspective on the issue. HFCs account for less than 2 per cent of the world’s greenhouse gases.
Switching off every air conditioner or refrigerator in the world will not save the planet! A worldwide ban on all HFC gases will not save the planet.
It makes no sense at all to talk about banning gases that are actively helping to reduce our carbon mark on the world - especially at this time when we are faced with additional costs of implementation of the F Gas Regulation.
What I would say to those that seek to legislate against HFCs is that there are many technical reasons why your preferred gases are not suitable for certain applications. As contractors and as an industry we are here to advise and to help you make the correct long term informed decisions based on years of combined technical experience.
But in order for this advice to have any effect you will have to listen to what we are telling you and stop taking advice from professional lobbying bodies who have hidden agenda or an axe to grind against certain sectors of industry. Whether their grievances are real or imagined is a moot point, the fact is that they do not argue rationally their case against HFCs. The one abiding argument against HFCs is the high global warming potential figures of many of these gases. But, as we said earlier, the secret is in the name: GWP – Global Warming Potential – the potential is only realised if the gases are released to the atmosphere. When these gases are safely and properly contained in systems, they have no direct impact on the environment – FACT. When you then consider their TEWI figures and discover that they make the most energy efficient gases in certain cases, no sensible scientist would or could argue against their use in these applications.
So, in conclusion, on the whole HFCs are undoubtedly a viable sustainable refrigerant in some applications. Remembering this fact we cannot allow a sweeping broad ban on all HFCs but merely need better control over how, when and where these gases are used to make sure we use them where they are more efficient and use the other alternatives for those applications where they are suited.
At a time when energy prices have been escalating and our Governments are committing us to ever more restrictive emission targets, we cannot seriously consider throwing away one of the most efficient heat transfer media for these applications.
Summary: The Big Picture
- HFCs account for less than 2 per cent of worldwide greenhouse gas emissions
- HFCs are the most energy efficient refrigerant available for medium to small sized AC applications
- GWP is irrelevant if gases are safely contained
- Consider the TEWI (Total Equivalent Warming Impact)