Foreword

With the recent energy crisis, this has resulted in a huge increase in energy costs for the majority of businesses. This can impact your bottom line, resulting in reduced profits or an increase in your product or service price. With the uncertainty surrounding the future of energy prices, this can lead to a sense of despair and helplessness.

There’s very little that you can do to influence the recent increases in your energy cost per unit (p/kWHr). However, an easy way to potentially make significant energy savings is to look at how you can reduce the energy consumption of your compressed air system. In our experience, most businesses are happy to explore installing LED lighting, solar panels or heat pumps. Energy savings that can be made on their compressed air system are often overlooked however and can often achieve of the most significant savings.

Calculating Your Energy Costs

So where do you start? The first thing you need to determine is how much energy your existing compressor / compressed air system is consuming. On some compressors, this can be tricky. However, if you operate a fixed speed rotary screw compressor, the easiest way to get a very quick estimate of this, is to take the below steps;

  • Go to your compressor controller and try to find and note down “Total Hours Ran“
  • On the controller, try to find and note down “Loaded Hours“
  • Divide the Loaded Hours by your Total Hours Ran to get your Loaded ratio and note this down
    • For e.g. 8,210 loaded hours / 25,200 total hours = 0.33 Loaded Ratio
  • Calculate your Total Annual Running Hours. This is how many hours per year your compressor runs for = Hours per day x days per week x weeks per year
    • For e.g. if you turn the compressor on at 8:00am and back off at 5:00pm Monday – Friday, this would be 9 hours per day x 5 days per week x 50 working weeks per year = 2,250 Total annual running hours
  • Calculate your Total Annual Loaded Energy. This is the productive energy consumption of your compressor = Main Motor Power x Loaded Ratio x Annual Running Hours
    • For e.g. with an 11kW compressor based on the above loaded ratio / annual running hours we would have = 11kW x 0.33 x 2,250 hours = 8,168 kWHrs
  • Calculate your Total Annual Unloaded Energy. This is the non-productive energy consumption of your compressor = Main Motor Power x (1 – Loaded Ratio) x Annual Running Hours x 0.5
    • Again using our example, this would be = 11kW x (1 – 0.33) x 2,250 x 0.5 = 8,291 kWHrs
  • Add both Annual Loaded Energy and Unloaded Energy together to get Total Annual Energy Consumption
    • Using our example, this would be = 8,168 + 8,291 kWHrs = 16,459 kWHrs per year
  • Multiply Total Annual Energy Consumption by your cost per kWHr to get Total Annual Energy Costs
    • Again using our example and an energy unit cost of 30p/kWHr , this = 16,459 kWHrs x £0.30/kWHr = £4,940 per year

The above process should take no more than 10 minutes of your time. This will give you a very rough estimate of how much energy your compressor is consuming and costing you to run per year.

Energy Savings

If you are operating a fixed speed compressor, there is a high chance that you can save on energy costs. Potential energy savings you can make by considering a more energy efficient VSD Compressor vary depending on your loaded ratio. In any event, savings of up to 50% are not uncommon however.

If you’re interested in exploring this further, we can help. We’re currently offering all of our existing customers and any potential customers in Scotland a free of charge energy audit. This entails installing a data logger on to your compressor and leaving this to run for a week. At the end of the data logging period, you would receive a full report detailing;

  • How much annual energy your compressed air system is consuming
  • How much you are spending on annual energy costs to run your compressed air system
  • Loaded Energy
  • Unloaded Energy
  • Potential Savings achievable by considering a more efficient compressor or set up of compressors

If you are interested in having this free of charge survey carried out, please contact our Sales Director Murray Irvine at mirvine@designairscot.co.uk or via phone on 07387150934.