Ventilation
Tackling air quality from the design stage
Andy Cardy of Fläkt Woods discusses the need for a holistic approach to system design in modern ventilation systems to optimise working environments and reduce energy costs
An Optimax active room diffuser from Fläkt Woods
year, battle- grounds are drawn in many offices. Two opposing teams are destined to clash over an impera- tive decision making process, which could affect the output of the entire company: should the thermostat be turned up or down? Ok, so this is a slightly exagger- ated scenario, but coping with cold, damp or stale air in the win- ter months, as well as overcoming the dry, hot and balmy summer, can be a tough challenge for a workforce and a facilities manager. However, whereas the temperature might be the main protagonist in an office conflict, it is actually the indoor air quality as a whole that needs greater consideration. Many of the non-domestic buildings in the UK will not be equipped with centralised ventila- tion systems, and will rely on more traditional methods i.e. opening a window. Although some consultants might argue that this can still be an effective way of improving indoor air quality, the UK Building Regulations have driven commercial property design to become increasingly
32 | March 2014 | HVR
Maintenance of good indoor air quality can be a complex task both in its initial design and ongoing monitoring
airtight to conserve fuel and power. This has led to the poten- tial degradation of indoor air qual- ity becoming an issue for system designers. After all, for occupants of commercial premises, such a problem can often trigger a notable reduction in productivity and comfort levels, so designing an effective system for all months of the year is essential.
Unfortunately, there isn’t a ‘one solution fits all’ option and, instead, maintenance of good indoor air quality can be a
complex task, both in its initial design and ongoing monitoring. In the first instance, ventilation rates have to be designed to a set occupancy level, but this can often be exceeded, causing a reduction in stale air removal and, conse- quently, a higher concentration of pollutants. If this scenario is cou- pled with a high density of occu- pants in a relatively small space, it can also lead to various problems, including increased levels of odours and noise, or increased transmittance of colds and flu. Other challenges include main- taining moisture levels and keep- ing energy usage to a minimum. There are many factors to con- sider when ensuring that a new building has an optimised indoor climate. Building services engi- neers need to look at ventilation rates, temperature, humidity, air purity and noise. One approach that is regaining momentum and is an ideal method for maintaining indoor air quality, is demand con- trolled ventilation. This helps keep the temperatures and ventilation rates at the required level and can be achieved by carefully specify- ing a range of products – such as air handling units (AHUs), axial/centrifugal fans, and air ter- minal devices (ATDs) – that can intelligently ‘communicate’ with each other to provide the optimum air quality.
A common component in com- mercial ventilation systems (espe- cially offices) is an air terminal device, or room diffuser. It might not always be considered a crucial element of a system but, when specified correctly, can provide some useful energy reductions. For this reason, manufacturers such as Fläkt Woods have developed ‘active’ room diffusers, which not only improve the performance of demand controlled ventilation sys- tems, but also maintain excellent comfort levels for occupants. By regulating the air distribution and controlling the flow rate, these room diffusers can ensure a constant air throw. In addition, where occupancy rates increase (a common occurrence in an office environment) and a higher ventila
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