Energy saving can be as easy as EC
Upgrading to electronically commutated fans in air-conditioning and cooling systems can reduce energy consumption by up to 70%, as Adrian Trevelyan of Airedale explains.
According to the Carbon Trust , large UK businesses are paying out more than £1.6 billion too much on their energy bills every year because many are yet to seize the full opportunity to cut bills by around 15% through energy-efficiency measures, savings which the Carbon Trust say are available through changes in behaviour and equipment and which represent highly attractive returns on investment.
The Carbon Trust also cites that for many businesses, a 20% cut in energy costs represents the same bottom line benefit as a 5% increase in sales.
The case for being more energy efficient is therefore a simple one, and is even more topical in the light of recent announcements that energy prices are set to rise.
One simple solution that can contribute to overall energy savings is to replace traditional AC fans with EC (electronically commutated) fans in precision air-conditioning and cooling applications, giving the potential to reduce power consumption by up to 70%.
EC fans are typically 50% more efficient than previous-generation fans and use variable speed control matched to load to eliminate unnecessary energy usage. In addition, Airedale’s intuitive controls improve energy efficiency still further by precisely matching speed to demand. The quiet, direct-drive motors bring further business benefits by removing the need for belt replacement, maximising system uptime.
EC are fully compatible with most systems, and units can be installed with minimal operational disruption. Typical payback period is less than two years.
EC centrifugal fans incorporate electronically commutated DC motor controls using semi-conductor modules which respond to signals from the indoor unit. The integrated AC to DC conversion combines the flexibility of connecting to AC mains with the efficiency and simple speed control of a DC motor. With its highly efficient backward-curved impeller, the EC fan significantly reduces power in comparison with equivalent AC fans at both full and modulated fan speeds. The in-built EC fan control module allows for fan speed modulation from 0 to 100%; in comparison, the modulating range of a standard AC fan is typically 40 to 100% of full fan speed.
An example calculation indicates the potential savings. Based on estimates that every kilowatt of power saved for each hour of continuous operation could bring savings of £876 per annum, the savings soon stack up.
For example a site with nine fans reduced its energy consumption by 64%, amounting to 58 342 kWh a year with a cost saving of £5834 a year.
Another site with 36 fans reduced its energy consumption by 33%, amounting to 409 968 kWh a year with a cost saving of £36 897 a year.
The energy savings can be even greater when carried out as part of a wider programme of energy-efficiency measures. To help identify areas where all-important savings can be made, many organisations are investing in energy surveys from HVAC and IT cooling experts like Airedale.
A typical survey would look at the performance of the complete cooling system, including refrigerant sub-cooling and superheats, as well as the chilled-water system. It would also assess the fan airflow path to make sure it is as efficient as possible. In addition to fan upgrades, the survey might identify additional efficiency opportunities through, for example, incorporating electronic expansion valves, upgrading inverters, compressors, coils and pumps or through installing software controls, energy meters and sequencers.
It’s important to choose a supplier who gives realistic assessments of the potential savings as well as demonstrating the right expertise. Airedale, for example, works closely with customers to help build a business case. This may involve installing the unit on a trial basis and taking before-and-after readings of power and airflow to demonstrate the savings. A reputable service provider will also re-commission the cooling system for optimum performance after completing any work.
Energy audits are set to become routine for large businesses
By 2015 most large enterprises will be mandated to carry out an energy audit every four years under Article 8 of the European Energy Efficiency Directive, which came into force in 2012. The Energy Savings Opportunity Scheme (ESOS), so-called because according to Energy & Climate Change Minister, Greg Barker, it will ‘help drive the take-up of cost-effective energy efficiency measures’ could, under conservative estimates, bring 0.7% energy savings per business through the implementation of energy-efficiency measures.
As a company, we are seeing an increasing demand for energy surveys and, as a consequence, retrofit and upgrade work. End users and contractors are now typically specifying more energy-efficient components like EC fans on new equipment, but there are still thousands of installed systems that will benefit enormously from being upgraded.
Schemes like ESOS, together with incentives such as interest-free Salix loans, demonstrate that investment in energy-saving initiatives is the way forward. Our figures are based upon costs today; with energy price rises now a reality, the projected savings can only increase.
Adrian Trevelyan is UK Service Manager with Airedale International Air Conditioning.