Inspection of air-conditioning systems – More than a legal requirement

Air-conditioning inspections are designed to improve efficiency and reduce electrical consumption operating costs. Here Stephen Gill, an approved air-conditioning inspector provides the background to the inspections and explains how the benefits exceed meeting a legal requirement.

Why are air-conditioning inspections required?
Building owners and managers who control air-conditioning systems have statutory obligations and duties of care in the operation and maintenance of those systems. A recent addition to these obligations for air-conditioning systems with an effective rated output of more than 12 kW is the requirement to have them regularly inspected by an approved energy assessor.

This inspection requirement stems originally from Article 9 of Energy Performance of Buildings Directive 2002/91/EC which was implemented in England and Wales by the 2007 Energy Performance of Buildings (Certificate and Inspections) (England and Wales) Regulations.

The regulation requires that the first inspection for systems over 250kW must have happened by 4th January 2009, and that for the remaining systems over 12kW they have until January 2011.

It has been estimated that there are somewhere between 20,000 and 30,000 systems with a rated output capacity of over 250 kW in the UK, and that only a fraction of these will have had the inspections by the January 2009 deadline. This is partly due to there being a lack of awareness of the regulation by building/system owners and also there still being a shortage of qualified inspectors. A possible third reason is that building/system owners are simply ignoring the regulations believing that they are unlikely to be actively policed. All the reasons are unfortunate because the aim of an inspection is to highlight improvements to the operation of the existing systems or opportunities to replace older, less energy efficient systems or over sized systems with new energy efficient systems and thereby reduce carbon emissions. So not having the inspections carried out for whatever reason is potentially an opportunity missed.

What does the inspection involve?
The first step of the inspection is to review records of the air-conditioning system. In more recent buildings, this information should be found in the building logbook or though from personal experience is that I have yet to find this is the case. Otherwise system descriptions and commissioning records may be needed to find plant types, sizes and locations. If this valuable information is not available there may be additional time and cost required in gathering the information even at the basic level of establishing what is installed.

Where information is available, this may provide useful performance factors such as the specific fan power of air-distribution systems, also any records of energy consumed or hours run may highlight excessive use and potential control issues.
The review of maintenance records and an initial visual examination of equipment allow a comparison to be made with industry good practice. Where a system is already well maintained and controlled, some aspects of the wider physical inspection may be omitted to keep costs low. However, where maintenance has not been undertaken or information is missing, there may be a need to investigate more thoroughly.
The visual inspection identifies system components, confirming that the plant matches the records. This often identifies that the information is out of date or incorrect and needs updating. As part of the inspection, the energy assessor will be look for such issues as external damage or blockage to heat exchangers, signs of leakage from refrigeration systems, and that basic operation is correct.

Estimate of cooling load
It is not a requirement of the inspections that a full design review is carried out; however rules of thumb are used to estimate the cooling load, based upon the current levels of occupancy, the activities being carried out, the IT and other heat generating equipment in use, and solar and other heat gains.
This check of the current load requirement can identify firstly opportunities to reduce these loads and secondly, opportunities to match the system more efficiently to the current load, for example by using variable-speed drives with relatively short payback times.

ReportAs part of the inspection, the energy assessor will provide a report to the building/system owner that will provide them with basic information regarding the efficiency of the air-conditioning system that they control, together with advice on how the energy efficiency or effectiveness of these systems might be improved.
Opportunities
Whilst the air-conditioning inspection itself is mandatory, it does not compel anyone to act on any advice given. However, acting upon the advice given in the report should result in attractive and cost-effective improvements that reduce the operating costs of the system.
There is a legal financial penalty for failing to have an air-conditioning system inspected by a qualified energy assessor and while this may be an incentive in itself to comply; the greater incentive must surely be the benefit of energy savings to be made.