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Does HVAC Filter Efficiency Effect Energy Use?

11 May 2012
Before I wrote this blog I didn’t know much about heating, ventilation and air conditioning system (HVAC) filters other than you should change the filters approximately every 3 months. As uninteresting as they sound- they are an important part of your HVAC system.
Each type of filter has a level of resistance that the air has to travel through. The more difficult it is for the air to pass through the filter, the more energy your system will use to get your home at the right temperature. This is why you want to change them at the right time. Generally, high filter resistance results higher air filtration efficiency. With higher air filtration efficiency there is most likely a higher pressure drop. Does this cause you to spend more money on your heating bills?
From the Studies I read(study 1, study 2, study3) the effect of a high pressure drop on energy efficiency in residential HVAC systems is typically minimal. Below is a table for two different filters that are exactly the same except pressure drop (highlighted in orange), which ends up in a $34 dollar cost difference over the year.
                                   
Efficiency MERV 14 MERV14
Filter Style 12″ Deep Rigid 12″ Deep Rigid
Media Area 120 sq. ft 120 sq. ft
Initial Price $70 $70
Initial ΔP 0.45 ” Water Gauge (WG) 0.65″ Water Gauge
Final ΔP 1.50″ WG 1.50″ WG
DHC 300g 300g
Filter Life 12 months 12 months
Energy Cost $276 / year $305 / year
Source
So, when shopping for HVAC filters, the level of air filtration you need for the health of your family comes first. After that is established, try to look for a lower pressure drop. I looked far and wide, on the internet, about how to know whether a filter has a low or high pressure drop. A fair warning that it may be difficult to find out since this search came up with minimal results. I would recommend asking your supplier or looking at specific filter brand websites.
80% of the overall lifetime cost associated with HVAC systems is from the actual energy use. Only 18% is from the initial  cost and maintenance of the filter. By reducing this energy use with a combination of smart heating/ cooling and lower filter resistance you have a great opportunity to save money and energy!
Green risk advisor
3m
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