An Inspector Calls

15 July 2007

Inspection of air conditioning systems is an integral part of Article 9 of the Energy Performance of Buildings Directive. Peter Grigg, and Hywel Davies explain what this will mean in practice for facilities managers from January 2009 or 2011

AS PART OF THE IMPLEMENTATION of the Energy Performance in Buildings Directive in England and Wales, the DCLG (Department for Communities and Local Government) introduced 'The Energy Performance of Buildings (Certificates and inspections) (England and Wales) Regulations 2007' on 29 March. These are described in Statutory Instrument 2007 No.991 and CLG Circular 02/2007.

Article 9 of the EPBD requires EU Member States to introduce a regime of regular inspections of air-conditioning systems of over 12 kW rated output. The new Regulations place a requirement on a person who has control of the operation of air conditioning systems, of collective cooling capacity over 12 kW, to ensure that the overall system is inspected by an accredited energy assessor at regular intervals not exceeding 5 years.

The new requirement is to be implemented in phases, depending on the size of the installation. The first inspection of systems of more that 250 kW rated cooling output is to be made by 4 January 2009, with the first inspection of the remaining systems of more than 12 kW rated cooling output being made by 4 January 2011. The first inspection of systems installed after 1st January 2008 should be within 5 years of putting into service. Also from January 2011, if there is a change in responsibility for a system and the new occupier is not given an inspection report on handover, then the new occupier will need to have an inspection carried out within three months of arrival. Energy assessors that carry out the inspections must be members of an approved accreditation scheme. The provisions come into force on 1st January 2008.

The provisions include minimum requirements for the written report to be provided to the manager, and on the manager to keep the most recent report. Enforcement is to be the responsibility of the Local Authority Trading Standards bodies. The Circular also makes reference to technical guidance being prepared on suitable methodologies for the inspection and assessment.

An Industry Working Group with representatives from CIBSE, FETA, ACRIB, IOR, HVCA, BRE, BSRIA and Summit Skills has been advising DCLG and preparing a CIBSE Technical Memorandum to set out a practical inspection procedure for air conditioning assessors to follow, and has also helped develop the draft European Standard (prEN15420) on air conditioning inspection.

Although the inspection and assessment will be mandatory and will represent a cost to the building manager, it does not compel managers to act on any advice given. The group has therefore proposed to keep the procedure at the simplest level necessary to identify likely poor performers, and to minimise cost and disturbance to operation, while still providing useful advice. The inspection and report will aim to encourage good maintenance and the efficient use of controls, while noting opportunities to reduce cooling loads or periods of operation of cooling equipment. It also takes account of potential risks and liabilities to the inspector and manager, and the likely availability and skill levels of the people needed to carry out inspections.

The inspection begins by reviewing records of the air conditioning system. In more recent buildings useful summary information should be in the building log-book. Otherwise system descriptions and commissioning records may be need to be examined to find plant types, sizes and locations. The information may indicate useful performance factors such as the Specific Fan Power of air distribution systems. Records of energy consumed or hours run could help identify unusual or excessive use and hence potential control issues. As assessments for both Article 9 and for Energy Performance Certificates gather momentum, records of both processes should be maintained so that information can be exchanged. Initially, however, records may be sparse, leading to additional costs to establish what is installed and where.

Reviewing maintenance records allows comparison with industry good practice. Where it is clear from the initial review that a system is already well maintained and controlled, then some aspects of the wider physical inspection may be omitted to keep costs low. Visual inspection identifies system components, confirming that the plant matches the records, and if not they should be updated. The assessor should look for issues such as external damage or blockage to heat exchangers, signs of leakage from refrigeration systems, and check that basic operation appears to be correct.

Examining system controls and settings offers the greatest potential for improvement and savings at low or no cost, for example resetting to reflect current use. The suitability of sensor types and locations, and system zoning, should also be assessed against the characteristics of the building and system and the current needs of the occupants, as there may be low cost opportunities to improve system control. Systems that allow simultaneous operation of both heating and cooling in the same space should be a particular concern.

Rules of thumb are used to estimate the cooling load, current levels of occupancy activities being carried out, the IT and other heat generating equipment in use, and solar and other heat gains. This indicates the size of the system in relation to the load, and whether there are opportunities to reduce these loads, perhaps by co-locating equipment in separate treated spaces or by applying solar control measures. There may also be opportunities to use more efficient equipment such as variable speed fans with relatively short payback times, or the manager may be informed of the availability of higher efficiency cooling plant that could be considered when systems are being renewed.

The report will identify the building and equipment inspected and include:
....System records and documentation
....The state of maintenance compared with good practice, recommending industry good practice where this appears deficient
....Low or no cost actions, such as clearing obstructed heat exchangers and making adjustments or improvements to controls
....Opportunities for reducing cooling loads or periods of operation, such as co-location of IT equipment for separate treatment, or the addition of solar control measures
....Opportunities to use alternatives such as free cooling, or employing more efficient technologies such as variable speed fan drives
....The scope for opportunities that would need further examination or clarification by more detailed examination by specialists, including signposting to sources of further advice and support such as the advice tools developed in the EU funded AUDITAC project

The report, should ideally be kept as part of the building log-book. The information will then be readily available to help others act on advice, prepare the building's Energy Performance Certificate, and carry out the next air conditioning inspection.

Article 9 refers to systems over 12kW rated cooling output, and the group recommended that this is interpreted to include smaller packaged cooling units where the total capacity under common management in a building exceeds 12kW. Such unitary, split and perhaps multi-split systems could form a class of equipment where the extent of inspection, the skills needed of the inspector and hence the associated training and qualification, could be reduced from that needed for more complex, centralised systems. The guidance offers a simplified, method and report format for these smaller systems.

Standard
The draft European Standard supporting the inspection (prEN 15240, Guidelines for inspection of air conditioning systems) should be available during 2007. This presents a flexible framework from which member states can derive their own procedures. Issues such as inspection frequency and the necessary skills and qualifications for inspectors are the responsibility of Member States, although informative annexes give suggestions. An associated draft standard (prEN 15239, Guidelines for inspection of ventilation systems) has also been developed to provide a similar framework for member states that wish to inspect natural and mechanical ventilation systems that do not include cooling, but this will not be adopted in England and Wales.

The Working Group's guidance has been prepared specifically for air conditioning systems providing comfort cooling for occupants and defined as controlled services in Part L of the Building Regulations. Other systems installed to provide conditioned environments for equipment or processes are often individual and specialised. The processes and the systems that service them are often business critical and closely monitored. While the general principles of inspection may be applicable to such installations, different knowledge and skills may be needed to understand their design and control, and to make observations on sizing and opportunities for improvement.

The draft CIBSE TM 44: 'Assessment of Air Conditioning Systems' is near completion, with publication expected in summer 2007. For systems which are already well maintained and documented the procedure will be relatively straightforward, and will inform operators and improve practice. The reports will provide the information to help those building managers with less experience of using and managing air conditioning to get better performance, reduce energy bills and cut carbon emissions.

....Peter Grigg is Principal Consultant at BRE Environment and Hywel Davies is Research Manager at CIBSE