Lines of defence

Pollen

Ensuring the highest quality indoor air means designing and specifying the right ventilation system. In order to do this, however, it is important to acknowledge that each element in a HVAC system has a significant impact on its operational efficiency and quality, says James Gafford of ECEX.

The success or failure of any HVAC project hinges on one central characteristic – the importance of recognising ventilation as a complete system (with each component working with every other to produce a result that is greater than the sum of its parts).

This is best illustrated by an approach adopted by many progressive businesses in the health and safety (H&S) sector.

In the late 1990s, the H&S industry developed a radical new method to study workplace risks called ‘layers of protection analysis’ (LOPA). Enlightened safety managers now use this to calculate the amount of risk reduction and levels of protection needed to ensure a safe workplace.

LOPA is particularly distinctive because it uses ‘layers’ of hazard control to manage risks ranked from most to least effective – in other words, it employs lines of defence.

The first control is elimination of the risk; this is followed by substitution; then comes engineering controls (such as electrical isolation); next is administrative controls (for example, good housekeeping); finally, personal protective equipment is, quite literally, listed as the last resort.

The same basic principle of LOPA (employing a stratified, hierarchical approach with each element following logically on from the last) can also be applied to the specification of ventilation equipment in order to improve its design and increase its effectiveness.

Moreover, to ensure the highest possible indoor air quality (IAQ), it is critical that all the equipment works well together; in other words, individual components each play their part in any effective system, but it is the ventilation system as a whole, operating in a synergistic way, that produces the best results.

Selecting the right equipment boosts indoor air quality, improves comfort, protects health, and enhances energy efficiency; the best design involves carefully considering each of these elements.

But truly successful indoor air quality starts with tackling dirty outdoor air by installing efficient prefiltration. Indeed, the importance of filtering external air can’t be emphasised strongly enough. After all, one of the main functions of an effective HVAC system is to prevent airborne contaminants from entering a building; this needs to begin outside with pre-filtration media fixed to air intakes blocking larger pollutants.

Technology is, however, not enough on its own. How that technology is treated also has a huge impact on the efficiency of the overall system.

There are many compelling reasons to take maintenance of HVAC systems in commercial buildings seriously . Apart from the need to comply with health and safety and environmental legislation, it makes sense to provide comfort for building occupants to avoid complaints and improve productivity.

It also saves energy and therefore operating costs, retains the assets’ value, enhances the business’s reputation, leads to better working relationships, and reduces disruption to the business.

Increasing energy costs are another good reason to employ an effective maintenance strategy; best practice maintenance can deliver cost savings of 10% to 40% compared with poor maintenance.

A critical part of the HVAC systems maintenance process is coil disinfection. While there is a wide range of cleaning options available for businesses, some are better than others.

As air passes across the coil it is cooled and this can increase condensation, creating the ideal conditions for airborne nasties to accumulate in a biofilm, reducing the efficiency of the coil and potentially leading to an influx of harmful air.

Disinfection of airflow using chemical-free ultra-violet (UV) airflow cleaning systems will prevent bacteria, viruses, and organic growth from taking hold of cooling coils.

Indeed, in the letter sent to the World Health Organisation by the scientific community, improvements to indoor ventilation, as well as the use of airborne infection controls, such as filters and UV lights, were listed as potential safeguards against aerosol transmission of viruses, including coronavirus.

Notwithstanding the protection cleaning systems provide against pathogens, they also improve indoor air quality by reducing organic growth throughout the entire HVAC system.

 Pollen counts

Itchy, swollen eyes; a runny nose or nasal congestion; wheezing; sneezing and/or coughing; sore, scratchy throat; fatigue; earache – these are some of the many miserable symptoms experienced by hay fever sufferers.

Hay fever is typically perceived as a summer malady; victims don’t expect to experience symptoms in the autumn and winter and, when they do, may pass them off as a seasonal cold. However, so-called ‘aeroallergens’ (airborne substances such as pollen, spores, and other biological or non-biological airborne particles) can be inhaled and cause allergic disorders all year round.

And these are widespread. Air pollution has, for example, been estimated to cause allergic rhinitis in 40% of the world population.

But pollen and other airborne debris such as leaves, insects, and other particulates are not only responsible for allergies; they can also clog up HVAC plant, causing it to run inefficiently or even fail completely.

Air intake screens – comprising a long lasting, weather-resistant mesh which prevents airborne debris such as pollen, leaves, insects and litter from clogging internal coil fins, perishable filters, and other components – are an effective way to mitigate the effects on air movement equipment of pollen and other debris.

The air intake screen that ECEX supplies, for example, is a vinyl-coated polyester fibre mesh that sits in front of essential HVAC equipment acting as a filter for airborne contaminants with negligible impact on air flow.

By stopping this debris from entering a system, machine efficiency and the lifespan of filters is increased, and maintenance requirements are reduced, all of which contribute to lower running costs while also helping buildings meet ever more stringent energy efficiency requirements.

But the advantages don’t end there; other solid business benefits of air intake screens include:

  • Less maintenance time and cost.
  • The elimination or a significant reduction in the need for coil cleaning.
  • Lower energy bills by lowering the energy consumption of HVAC equipment.
  • Fewer cooling tower water treatment chemical requirements.

Avoiding a breakdown

The risk of ventilation failure mounts as outdoor pollution increases, especially on externally sited HVAC equipment. If air handling units, chillers, dry air coolers, condensers, cooling towers, air intakes, and other ventilation-related systems are blocked by pollen or other airborne debris (for example, leaves, insects, and feathers), they work less efficiently and effectively.

The results of this can be devastating. Apart from the obvious impact on the comfort of building occupiers, consequences also include greater energy usage and therefore bigger bills, higher maintenance costs, and more carbon emissions.

Indeed, there are many compelling reasons to take the maintenance of HVAC systems in commercial buildings seriously. Apart from the need to comply with health and safety and environmental legislation, it makes sense to provide comfort for building occupants to avoid complaints and improve productivity.

It also saves energy and therefore operating costs, retains the assets’ value, enhances the business’s reputation, leads to better working relationships, and reduces disruption to the business. Increasing energy costs are another good reason to employ an effective maintenance strategy; best practice maintenance can deliver cost savings of 10% to 40% compared with poor maintenance.

The cost of sound maintenance is absurdly low compared with the cost of dealing with, say, a catastrophic air conditioning failure or broken-down AHU. Effective maintenance can also make a significant contribution to the bottom line by ensuring that HVAC equipment is energy efficient and therefore produces lower power bills and higher environmental performance.

But the most compelling argument in favour of properly implemented maintenance is that it guarantees reliability. Just about every business indicator – energy efficiency, safety, environmental performance, morale, retention, customer service – will improve if you establish reliability as a core value.

Even simple measures such as cleaning and changing filters as part of a planned maintenance programme can reduce the likelihood of equipment failure and boost the energy efficiency of the equipment.

But where should you start? We have produced a free, wide-ranging guide that explains the steps to maintenance good practice, including how to draw up a maintenance policy, developing a maintenance strategy, details of different forms of maintenance and assess needs.

James Gafford is Contract manager at ECEX

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