Plant & Works Engineering
Pressure to deliver
Published:  08 July, 2011

Large-scale users of energy, manufacturing and process industries are under particularly strong pressure to deliver a programme of action to reduce CO2 emissions and meet Government targets. This pressure has manifested itself in a constant stream of legislation, standards and regulations, so it is little wonder that many premises and facilities managers and factory owners may be confused by this myriad of rules and regulations.  Here, Simon Keel of Daikin UK, looks at some of the key requirements and contradictions of carbon reduction legislation for air conditioning and how managers can best meet them. 

Building managers could be forgiven for feeling bogged down by what may be viewed as a constant bombardment of changing carbon reduction legislation. What with EPCs, DECs and Energy Performance in Buildings legislation, as well as recent changes to Building Regulations, there is a continual raft of changing rules and regulations that needs to be understood and addressed in the battle to reduce the energy used in, and the carbon produced by, our buildings.

The extent of the inertia – or even antipathy – towards this wave of legislation can be illustrated by statistics showing the high levels of non-compliance towards mandatory air conditioning inspections in non-domestic buildings. In fact compliance with Energy Performance in Buildings and F-gas legislation is estimated by the Chartered Institute of Building Services Engineers (CIBSE) to be minimal and to pose a real threat to the chances of the UK meeting its carbon reduction requirements.

However, if building managers were to view the energy inspections of their air conditioning systems as a route by which information can be gathered to improve thermal efficiency, significant energy performance improvements could be achieved.

As well as assessing how an air conditioning system is functioning at the point of inspection, the role of the inspector is to offer advice on how improvements in performance can be made going forward – vital information in providing even higher reductions in a building’s energy usage.

Of course there will be a cost implication and a natural resistance to spending more money but current feedback from inspectors’ reports shows that long term savings can often pay for the initial outlay. Building owners and managers who enter into the spirit of these inspections are the ones who will profit the most.  By cooperating fully both before and during the visit, the quality of the report will be raised to the highest level and thus deliver greatest value in terms of savings. 

Another legislative area that could appear confusing or contradictory are measurement systems such as BREEAM. Most managers quite rightly want their buildings be energy efficient and to minimise their impact on the environment. Obviously there is a cost/benefit analysis to be done, but by-and-large a building that scores highly under measurement systems such as BREEAM means that prospective end users will benefit from lower fuel bills that result from more energy efficient buildings.

But what happens if the assessment apparatus penalises the most energy efficient systems, or if measurement systems are contradictory or use differing standards? This is happening in the UK today. Take, for example, the BREEAM system. One of the best ways to reduce emissions is to use highly efficient equipment such as heat pumps which minimise the use of power, thus cutting down on the consumption of fossil fuels. However, because this equipment is driven by a refrigerant which, weight for weight, has a higher atmospheric carbon equivalence than CO2, with the BREEAM rating system heat pumps lose credits for using seemingly harmful refrigerants.

But surely it is bad science to condemn all hydrofluorocarbons out of hand and assume that it is better to install an alternative that uses a less efficient refrigerant, which has an approved low Global Warming Potential? Unfortunately this is exactly what is happening in many cases. There are specifications written for, and environmental credits given to, just such scenarios. It seems the headline properties are the only ones that matter.

Looking at BREEAM in more detail,  air source pumps score highly in the energy section as they use renewable heat and are more energy and carbon efficient than systems that use conventional fossil fuels. Whilst it is true that by using the latest heat pump technology with integrated heat recovery equipment, the number of BREEAM credits received will be increased, because there is a contradiction in the way heat pumps are assessed, they are also penalised under the pollution section of the system.

In this section (BREEAM Pol 1 – 3), credits are awarded for systems that use: less than 5kg of refrigerant; refrigerant with <5 Global Warming Potential or provide a detection and pump down facility should a leak occur. This reflects concern over the possible release of gasses with high global warming potentials.

However, most non-domestic buildings with air conditioning are ruled out of the first credit as they will use more than 5kg of refrigerant. Specifying <5 GWP pre-supposes that any system using a high Global Warming Property (GWP) refrigerant will produce more greenhouse gas (GHG) emissions than one using a low GWP one. There are many systems using gasses such as R410A which can be shown to generate lifetime emissions far lower than less efficient but lower GWP refrigerants. This is true even where an above average leakage rate is used for calculation purposes for the HFC in question.

This assessment procedure totally ignores the Total Equivalent Warming Impact equation (BS, EN 378-1) which looks at all the factors involved with an installation and works out the total quantity of greenhouse gasses, or their equivalents, that are released over a period of time. Unlike many environmental scoring systems which are based on a doctrine or a philosophy this mathematical calculation only reflects the facts that have been entered into the equation. It has no preference about one system or refrigerant over another.

But by using such an equation, it can be seen that even when we consider the direct carbon impact of any potential refrigerant leakage (which might theoretically occur when using a refrigerant such as R410A) and add this to its indirect carbon emissions (which are far lower than many alternatives), the lifetime carbon emissions may well be significantly less than using an apparently lower GWP refrigerant such as CO2, which is nowhere as efficient and is responsible for far greater carbon emission at power stations during its operation.

There is also a problem with the use of low GWP refrigerants, such as hydrocarbons, ammonia and CO2 (alternatives suggested by BREEAM), which are either explosive, highly toxic or low performing. Direct expansion refrigerant systems, such as those used by heat pumps and which require the use of HFCs, are highly energy efficient and can dramatically reduce carbon emissions in buildings.

Overall, heat pumps have an important role to play in cutting down on carbon emissions, but it is vital to look at the big picture and be clear as to what exactly we are trying to achieve. By taking this holistic view it will be possible to cut energy consumption, reduce carbon emissions and pay less to heat and cool non-domestic buildings.


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