MERV 11 with Carbon Pre-Filters

July 12, 2010

Richard Navarro

Google

LEEDuser Basic Member

82 thumbs up

July 12, 2010

The building that is undergoing certification has MERV 11 filters with Carbon Pre-Filters. According to our facilities team, this combination of a Carbon pre-filter paired with the MERV 11 has a stronger filtration than a MERV 13 filter.

Would this be an acceptable alternative to the MERV 13 filter requirements?

The carbon pre-filter is the "Vari-Klean Ultra High Efficiency Gas Phase Adsorbers" it has no MERV rating.

Any help would be great on this.

Post a reply

Tristan Roberts

Representative
Vermont House of Representatives

LEEDuser Expert

11478 thumbs up

July 12, 2010 - 11:05 pm

You might be able to do this but it would be through an alternative compliance path, and you would have to demonstrate definitively that your filtration is as good as or better than MERV 13. Some data or evidence would be required, in other words.

Dan Ackerstein

Principal
Ackerstein Sustainability, LLC

LEEDuser Expert

819 thumbs up

July 13, 2010 - 12:03 pm

I agree with Tristan - I think the key here is confirming the type of filtration at issue. My understanding (or lack thereof) is that there may be a difference between the effectiveness of a filtration process in removing particles and the SIZE of the particles being removed. MERV refers to the latter, so your system may be very effective at removing particles, just not particles as small as MERV 13. Worth exploring further with your filter vendor or HVAC team.

Jean Marais

b.i.g. Bechtold DesignBuilder Expert

LEEDuser Basic Member

832 thumbs up

July 14, 2010 - 1:41 am

A MERV 13 filter will be effective (% wise) at removeing particles of different sizes...here's a nonsense example:
particle size: 1 2 3 4 5
% effective: 80 75 20 65 90
under specific lab test constraints/conditions/proceedures

You would have to demonstrate that your filter combination will be as good as or better than the baseline MERV numbers. The manufacturers would most likely have to give you this information or find someone who could.