Modern Building Services

MODERN BUILDING SERVICES JULY 2022 17 FEATURE INDOOR AIR QUALITY T he 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 sumof 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 themain functions of an effective HVAC system is to prevent airborne contaminants fromentering 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. ➜ 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. Lines of defence