Airing filtration issues
The simple need to change air filters offers the opportunity to both save energy and also improve indoor air quality, as Peter Dyment of Camfil explains.
In an average commercial building, 50% of the energy bill is attributable to the HVAC system. 30% of that is directly related to the air filter — yet the filtration part of this consumption is substantially and invariably overlooked. Procuring the right filter can be a huge benefit to an organisation’s energy saving strategy. A badly selected filter can cost over £500 per year. Low-energy air filters typically save 30% in energy consumption.
Property, estates, FMs, building and energy managers are realising the substantial financial and energy saving opportunities that exist by replacing existing air filters with energy-efficient filters. In 2013, Camfil delivered ‘identified energy savings’ of over £1 million to UK sites by installing low-energy air filters in HVAC systems.
Energy-saving quick wins for buildings are important, but it is equally important to maintain a clean and healthy indoor working environment. Reducing power consumption of HVAC systems with energy-efficient filters that also improve indoor air quality (IAQ) is a practical way to combat the health threats of indoor air pollution.
The main threat to health comes from two types of mainly traffic sourced air pollution. One is fine combustion particles known as PM2.5, the other is the associated combustion gas, which is principally nitrogen dioxide (NO2).
Currently, the levels of nitrogen dioxide in central London (Oxford Street) are stated to be the highest measured level of any city in the world. This air-pollution data comes from the Government-contracted air-monitoring station in the vicinity of the main shopping locations in Oxford Street. Pollution in the outside air can readily enter most of the buildings in the area because the constant movement of shoppers, and people entering buildings means that this polluted air will also be drawn inside the shop buildings.
If the building cannot be readily made airtight then the solution has to be effective cleaning of incoming outside air.
There are high-efficiency filters that can remove health-damaging fine particles and noxious gases (NO2) to an efficiency of well above 90%. The filtration solution and protection for people inside buildings is available, but not always properly put into effect.
Using better air filters does not mean higher energy costs. A recent study at the ASSL building in collaboration with Cardiff University estates staff showed a 21% monitored energy reduction during filter life using low-energy air filters in AHUs compared with existing air filters (both F7 class). These filters also showed a 21% improvement in particle-stopping efficiency. Once a building HVAC system has been installed it is not easy to deal with subsequent problems that may arise without expensive modifications.
One solution to reducing indoor air pollution is a self-contained air purifier, such as our Camcleaner which supplies clean filtered air at the point of need with minimal setup problems. Camcleaners come in a variety of sizes and types of finish to reflect the numerous needs of the market — from an executive retreat or office to an industrial setting with a more demanding load situation.
So how bad is the air pollution in areas such as Oxford Street in London and how can a self-contained air purifier help improve indoor air quality?
The World Health Organisation sets a maximum annual mean figure of 40 µg/m3 for nitrogen dioxide (NO2), and the Oxford street annual mean figure of 135 µg/m3 is over three times greater. There were also 1568 one-hour spiking events over the last year that broke the WHO limit of 200 µg/m3 according to David Carslaw, Researcher at Kings College.
The Government Environmental Protection — Air Quality Standards Regulations 2010 looks to have been clearly exceeded in this regard. PM2.5 fine combustion particulate pollution comes from the same traffic source, so the levels are again well above the WHO annual mean of 10 µg/m3 by a factor of two to three times in these parts of London.
Using Camcleaner units sized and sited close to exposed entrance and exit points in buildings will filter clean and re-circulate the air and take out both of these health damaging pollutants at point of need.
Peter Dyment is air quality and building energy consultant at Camfil UK.
