The growing demand for controlled ventilation

Published:  06 September, 2012

Xpelair, demand controlled ventilation
Demand-controlled ventilation as the ventilation solution of the future ó this is Xpelairís Xcell system.

With a raft of ventilation solutions on the market, Steve Mongan of Xpelair looks at some of the options available to specifiers within the building industry and balances the argument for fixed versus demand-controlled ventilation.

Figures from BRE suggest that Europeans spend about 90% of their time indoors and, as such, can be exposed to a wide variety of air pollutants. It is also well known fact that indoor air quality can have a significant impact on the comfort and, more importantly, the health of occupants of a building.

A number of studies have shown that alongside the health implications, poor indoor air quality and lack of proper ventilation can reduce productivity and increase absenteeism, which led to the coining of the phrase ĎSick Building Syndromeí.

Government targets and Building Regulations have been in place for some time and strengthened to stipulate the provision of adequate ventilation within a building. As buildings become increasingly airtight in a bid to reduce carbon emissions and increase energy efficiency, the requirements for fit-for-purpose ventilation become an integral and important part of building design.

Addressing the needs of the occupants of a building whilst balancing the requirement to meet Government targets can be a challenge. However, for those specifying ventilation solutions within commercial buildings, there is an increasing array of options available.

The system of choice for many years now has been fixed ventilation. These systems, which have become more and more efficient in recent times, guarantee that airflow and ventilation is set to the perceived maximum building occupancy.

The benefit of fixed ventilation is that it will never under-ventilate a space. However, this also acts as a limitation of the system, because as it runs at a permanent set rate, efficiency can be lost when the space is under utilised. Heating and cooling losses when this occurs can be considerable.

Another type of system that is established in the UK market but has been more widely adopted in mainland Europe to date is demand-controlled ventilation (DCV).

The main reason is that fixed ventilation has been the industry standard in the UK for decades. However, with legislation driving an energy-efficient future, DCV is now rising in popularity as a solution that can play its part in meeting national and global carbon challenges.

DCV differs from fixed ventilation in the way that it uses sensors placed around a particular space or zone that feed back intelligence to the zone controller in real time, which in turn modulates the airflow as required.

Sensors can monitor everything from occupancy through to temperature and CO2 levels, and the DCV system adjusts the ventilation based on the information received to match demand, consequently minimising wastage and securing substantial savings in energy, running costs and carbon.

The key with DCV is calibrating the multiple sensors that the system relies on correctly to ensure that it conforms with Building Regulations. Doing this will ensure optimal indoor air quality is achieved and mean less wastage in the applications where it is used.

To help educate the industry on the use of DCV and drive demand for these types of systems, not only have the Building Regulations adapted the ISBEM tool to reflect the efficiency rates of DCV, but this technology and its use to optimise energy consumption is also well established within the non-domestic compliance guide.

Moving forward, We see DCV as the ventilation solution of the future. However, whilst the technology is not a new concept, the fact that it is not as widely adopted in the UK means it is going to take some time for it to secure a solid foothold in the market. Thereís no doubt, though, that in the coming years that DCV systems will begin to gain prominence because of the considerable energy savings and carbon footprint reductions that this form of control offers.

In the meantime, there is still obviously a place for fixed ventilation. System-efficiency improvements, the fact that fixed ventilation still conforms to Building Regulations and because specifiers and installers know and feel confident using this technology, means that fixed ventilation will continue to be widely implemented and have a strong place in the market.

Steve Mongan is head of marketing with Xpelair.

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