Periodic Cleaning of HVAC Coils Reduces kWh Consumption per m2

The ‘Building Efficiency Accelerator Report’, published in 2019 by Emirates Green Building Council, highlighted some very interesting insights. When benchmarking Hotels, Schools and Malls in the UAE, the report not only highlighted the spread between the ‘best’ and ‘worst’ performers in each of these sectors, it also clearly shows how much energy is used per m2, to keep buildings running throughout the year.

With COP28 around the corner, it is interesting to revisit some of the findings in this report and zoom in to the median energy we use per m2 in 3 dominant building types in the UAE.

What is Your Energy Usage?

Based on real usage data in a sample of 121 properties, the report offers a very useful insight in the energy consumption per m2 in hotels, schools, and malls.

  • A median hotel in Dubai consumes 252 kWh per m2, whereas the best performing hotel consumes 58% less energy than the worst performer.
  • A median school in Dubai consumes 134 kWh per m2, whereas the best performing school consumes 61% less energy than the worst performer.
  • A median mall in Dubai consumes 465 kWh per m2, whereas the best performing mall consumes 35% less energy than the worst performer.

Albeit that the lion share of the daily energy consumption can be allocated to cooling, several factors, such as the building design, the age of the building structure and equipment, play a big role in energy performance. But so do the building operations and maintenance. Putting all of this in the context of the climate zone in which we operate, ASHRAE Zone 0B ‘Extremely Hot Dry’, Facilities Managers deal with significant daily challenges to optimize energy use, or at the very least, try to maintain building operations at an optimum efficiency level.

Tools and Insights like Never Before

There has been much development in pro-actively managing building systems over the past years, with technology becoming more affordable and easier to implement. As IoT, building automation and sensor systems become more mainstream, we get reliable (real-time) performance data, where we can manage buildings smartly. It is now possible to bring supply and demand closer together by, for example, aligning cooling requirements with space occupancy. Many companies have invested, or are investing, in technology that allows them to consume energy when it is needed in that building space.

However, there will always be certain limitations to what technology can resolve for us autonomously. Certain factors must be addressed periodically with manpower: equipment maintenance.

HVAC Coils Function as a Mega Filter

Much of our built-up area is air conditioned, leading to cooling taking a very significant share of the total electricity consumption. Larger HVAC systems practically run all-year round, making them inefficient over time. Despite the filters fitted in those HVAC systems, the inefficiencies manifest themselves because the AC coil gets dirty, resulting in airflow obstructions, as well as an impairment of the heat transfer; the extraction of the heat from the air that passes through. Since coils are densely packed, to create maximum surface area to extract heat from the air passing through, the coil itself basically functions as a mega filter, in which dirt can easily settle and accumulate, and get congested, blocking the airflow. Simply put, this results in the HVAC unit needing to work harder to pull (or push) the designed volume of air through the coil and cool it. The result is an increase in energy consumption, which also creates an unwanted and unneeded stress on the mechanical parts of the system.

Besides the negative effect on thermal comfort, also consider that the humidity within the depths of the coil, creates invisible fouling. Organic fouling buildup can consist of mold, germs, and bacteria, potentially compromising the Indoor Air Quality (IAQ).

Predictable Low Running Costs

It is no surprise that Periodic Preventative Maintenance (PPM) is a must to keep HVAC systems running to an optimal level. The most important objective of PPM is to ensure that the airflow remains unobstructed. First and foremost, to optimize IAQ and thermal comfort, but also to lower your running costs. In other words, to lower your energy costs per m2 and CO2 emissions. You shouldn’t focus on ‘problematic’ units only when performing PPM, but the entire HVAC setup. The periodic deep cleaning of all Air Handling Units (AHU) gives you an immediate return on investment, since these are typically larger units that run for many hours per day, giving you a saving opportunity that compounds very quickly. By eliminating coil fouling across your entire AHU setup, even a small energy saving of for example 1% adds up quickly to a substantial saving in big structures, such as a hotel or shopping mall. As an example, a 1% saving in HVAC related energy consumption, for a floorspace of 250,000 m2, could amount to a reduction of 800,000 kWh per annum.

As discussed, the primary energy saving is linked to the efficient running of a specific AHU, however there are other areas where savings are made as well. As coils transfer heat more efficiently, since fouling is removed periodically, managing chilled water supply becomes easier. For example, there is no need to lower the inlet temperature of the chilled water below designed levels, to compensate for inefficient heat transfer. This is also an immediate energy saving opportunity. Furthermore, due to the system being less stressed, the wear and tear on mechanical parts will reduce breakage / fix costs (and downtime). In the long term, the asset life will be prolonged, eliminating very expensive replacement costs.

Can You Keep Your Coils Running at an Optimum?

The short answer is ‘Yes.’ The implementation of a simple and effective cleaning strategy, and protocol is much easier than you think, and very cost effective. At FCLT-E we are passionate about innovating repetitive maintenance protocols and implementing products that have an immediate and measurable effect. Whilst contributing to the de-carbonization effort within companies, we want to positively influence the health of the buildings that we work, live, and play in. And finally, we want our solutions to have a positive effect on the environment, by eradicating harsh and damaging chemicals from our cleaning practices, and to only work with completely biodegradable products.

A growing number of reputed hoteliers, mall operations and FM Service Providers are working with FCLT-E and are impacting their daily operations positively already. If you want to know more about the practical product solutions you can implement in your building, you can contact our team directly. We are happy to share our experiences and client cases with you.

For more information, call us or send a message.