The value of air-conditioning inspections
Inspections of air-conditioning systems are now required by law — and could bring real benefits to users, as Hywel Davies and David Davies explain.
Since January 2009, air conditioning systems with a cooling capacity of 250 kW or more must be inspected to comply with the Energy Performance in Buildings Regulations in England and Wales. Parallel regulations apply in Scotland and Northern Ireland, with a deadline of January 2010 for first inspections to be completed in Northern Ireland.
All these regulations implement the inspection and energy certification requirements of the Energy Performance in Buildings Directive. All systems over 12 kW output throughout the UK must have been inspected by January 2011.
The regulations require the ‘responsible person’ to commission an inspection and to receive and retain a report. If a building has more than one system, and they are controlled by the same person (or organisation), they all require inspection. The capacity of the systems should be aggregated to determine the overall size and when the first inspection is required.
The systems must be inspected by a competent person belonging to a scheme accredited by the Department for Communities & Local Government (CLG), or be recognised under a protocol with the Building Standards Division of the Scottish Government in Scotland. There are several such schemes, one of which is operated by CIBSE Certification, which includes the necessary arrangements for Scotland. This is a scheme for air-conditioning assessors for both complex and simple systems and is one of a range of accreditations offered by CIBSE Certification in support of the Energy Performance in Buildings Regulations.
The inspection procedure is kept simple and aims to identify poor performers and minimise costs and disturbance. CIBSE, in partnership with the HVCA, BSRIA, Institute of Refrigeration and others, has produced a detailed inspection procedure in CIBSE TM44. It describes what should be done when inspecting plant, and gives advice on how to assess cooling loads in the building so the assessor can meet the requirement to advise on the size of the system in relation to the cooling load.
The steps to be undertaken by an assessor are summarised in the panel.
These inspections ensure that existing systems are being operated and maintained correctly. They also give owners and operators information about the performance of their buildings and plant, enabling them to identify opportunities to save energy and cut operating costs. Whilst the inspections are mandatory, it is for the owner to decide whether to act upon the advice within the report. However, the report is likely to identify potential energy and cost savings and also give an indication of issues such as forthcoming restrictions on the refrigerants used in systems.
Hywel Davies is CIBSE technical director and David Davies currently works in the CIBSE technical department on secondment from AECOM (formerly Faber Maunsell).
The four stages of an air-conditioning inspection
Step 1: Inspection of documents and records.
The first step in the inspection is to review records of the air-conditioning system. In more recent buildings this should be found in the building log-book, which is now a requirement under the Building Regulations, otherwise system descriptions and commissioning records may be needed to find plant types, sizes and locations. This information may provide useful performance factors such as the specific fan power of air-distribution systems, while records of energy consumed or hours run may indicate excessive use and potential control issues. Where data is not provided, the assessor may use rules of thumb to estimate cooling load, current levels of occupancy, activities being carried out, heat generating equipment, solar and other heat gains.
Step 2: Inspection of equipment.
Reviewing maintenance records and examining equipment allows comparison with industry good practice, and confirms that the plant matches the records, which should be updated if required. Where this shows the system is already well maintained and controlled, aspects of the wider physical inspection may be omitted. However, where maintenance has not been undertaken or information is missing, the inspector may need to investigate further. Examining system controls and settings generally offers the greatest potential for low- or no-cost adjustments, improvements and savings.
Step 3: Advice for system improvements.
The assessor shall highlight any faults with the equipment. The size of the system is compared to the load to check that the system is of an appropriate size. The assessor can also suggest where there are opportunities to reduce the cooling load or 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 more efficient cooling plant to consider when systems are renewed.
Step 4: The air conditioning inspection report.
The report should ideally be kept as part of the building log-book so it is readily available to review or act on its advice, prepare an Energy Performance Certificate or carry out the next five yearly inspection. The regulations require the responsible person to retain the report and, when they move on, to pass it to their successor.
Further information
To purchase CIBSE TM44: ‘Inspection of air conditioning systems’ visit the CIBSE bookshop at www.cibse.org or ring 020 8675 5211. Note that TM44 now includes additional details of the requirements in Scotland and Northern Ireland. For more information on the CIBSE Low Carbon Energy Assessor Scheme and becoming an air-conditioning inspector visit www.cibsecertification.co.uk
