Seasonal factors

1 July, 2010

With the unrelenting stream of legislation coming into force designed to reduce carbon emissions from the built environment, facilities managers could be forgiven for sounding a collective groan at the news that there is more on the way. Pending EU legislation means that air-conditioning equipment will have to meet even more stringent standards. But it may not all be bad news. This further legislation may offer opportunities to dramatically cut running costs.

Facilities managers have faced a constant bombardment of changing carbon reduction legislation. First there were EPCs and DECs, rapidly followed by wider energy performance in buildings legislation, as well as imminent changes to the building regulations – to name but a few. These continually changing rules and regulations need to be understood and addressed if we are to win the battle to reduce the energy used in, and the carbon produced by, our buildings.

However, statistics showing the high levels of non-compliance towards air-conditioning assessment in commercial buildings, for example, demonstrates the extent of the inertia towards this legislation. Compliance with energy performance in buildings and F-gas legislation is estimated by CIBSE to be so low that it could pose a real threat to the chances of the UK meeting its carbon reduction requirements. Only five per cent of air-conditioning systems are thought to have been inspected in line with this legislation.

By viewing the energy assessment of air-conditioning systems as a route by which information can be gathered to improve thermal efficiency, significant energy performance improvements can be made. As well as assessing how an air-conditioning system is functioning at the point of inspection, assessors can 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.

One such area of improvement is how real-life performance of an air-conditioning system might vary from its predicted performance. Generally this is expressed in terms of nominal performance, but this statistic can hide the significant differences that exist between rated and actual performance.

Seasonal efficiency
In order to close this gap, there is yet more legislation afoot – a draft Energy using Product (EuP) directive from the European Commission, which means air-conditioning equipment will soon need to demonstrate ‘seasonal efficiency’ on energy labels.

By complying with this draft legislation earlier rather than later, there is a huge opportunity to reduce energy usage in a building and therefore its running costs.

The new EuP legislation proposes that seasonal efficiency ratings will be required for all air-conditioning equipment, meaning that performance will be calculated and expressed according to its seasonal efficiency rating over the year. This rating will eventually appear on a new energy label, giving users a better idea of anticipated real-life performance.

Once the new regulations come into force, all new units purchased after that date that are unable to meet EuP requirements will be banned.

At Daikin we have already launched technology to address this legislation. Our new Sky Air Seasonal Inverter, designed using eco-design principles, has optimized inverter control for improved energy performance all year round – delivering higher annual seasonal efficiencies than the latest super inverters and offering major improvements over contemporary non-inverter systems.

This new seasonal inverter energy rating takes account of multiple cooling and heating temperatures, as well as the unit operation at partial load instead of just at full capacity. It will also consider the power consumed by equipment in auxiliary mode when the compressor is off.

As well as advising on improving seasonal efficiencies, a good air-conditioning assessor should also be able to offer advice on the many other ways that energy efficiency can be improved, such as by monitoring efficiency remotely or by the use of ‘intelligent systems’.

Taking remote monitoring first. The operating efficiency of an air-conditioning system not only has an impact on emissions and energy consumption, it also affects the reliability, cost of maintenance and the life expectancy of the system. If air-conditioning systems can be kept running at an optimum level, it results in a longer lasting, cheaper-to-run system that produces fewer emissions.

The very best remote monitoring will also offer an energy-saving function. For example, the Daikin Network Service System is designed to remotely adjust the operating parameters of Daikin air conditioners to ensure optimum energy efficiency. Energy saving is obtained by using remote weather forecast information (local to the specific site).

This information is combined with the data that is collected from the air conditioners. Judgments are then made according to this information, and if energy-saving measures are possible they will be made remotely. This system will also account for occupancy levels and variations in installation (piping lengths and so on) when calculating energy-saving potential.

Heat recovery
If a building is looking to achieve really impressive energy efficiencies, the use of heat recovery in balanced mode within a VRV system can also be employed. This intelligent approach to heat recovery can deliver exceptional co-efficiencies of performance (COPs) of up to nine or even 10.

Achieving balanced mode operation might involve cooling one area of the building, which is experiencing the highest heat gains, and transferring that reclaimed heat to other areas of the building that require heating or, indeed, hot water, which is now also possible within a heat recovery system.

To do so, the indoor units need to be arranged to maximise the occasions when this balanced operation can take place, with the heat recovery system diverting recovered heat to wherever it is needed, thus contributing significantly to the goal of zero heat rejection.

Effective design
However, to achieve these industry-beating COPs of nine and 10, it’s vital to analyse right from the start a building’s multiple requirements, usage patterns and varying occupancy levels, in order to design a fully integrated system that optimises energy efficiency and heat recovery.

Although these efficiency levels may seem out of reach for many, they are a very real possibility if they are designed in from the outset. Through effective system design and regular ongoing air-conditioning assessments, performance efficiencies can be improved in commercial buildings, making it possible to achieve much higher levels of energy efficiency and carbon reduction than previously envisaged.

Not only will this help meet the country’s carbon reduction targets, it will deliver energy cost savings that will make a real difference to a company’s bottom line.