Author: TheeDesign Studio
Initially developed to protect an HVAC system’s coils, ductwork and other components from dust and dirt, air filtration systems have evolved to include measure to protect and maintain a building’sindoor air quality. Most building managers and home owners acknowledge the relationship between air filtration and the quality of the air in the building, however the relationship between air filtration and energy use seems to be bypassed and overlooked. Unfortunately, many building mangers tend to focus on the filters price and look for ways to lower operating expenses by downgrading their filters.
In actuality, the filter directly and greatly impacts the operating costs of the system, more so than the cost of the filter itself. Depending on the type of filter and the application, the operating expenses can outweigh the filter cost by a factor of five to ten.
When trying to find a balance between indoor air quality and reasonable operating costs, it is important to understand how the air filtration system works and which differences impact the energy usage for your HVAC system. Here’s how it works.
A filter is installed in the HVAC system and works to remove dust, dirt and other particles from the air as it passes through it into the system. This filter adds resistance to the air system, requiring the system’s fan to use more energy to supply the proper air volume for the room. The unfortunate issue is that high quality air filters, ones that provide the highest level of particle filtration, tend to also increase the resistance and cost of operating the system.
The entire issue has gotten a little more complicated as outdoor air has become more polluted. Bringing in air from outdoors requires more filtration than in the past, and because of this, the minimum airflow volume is higher than ever, requiring more energy from the fan. Of course, reducing resistance of the air filter will decrease fan energy requirements, but this translates into more particles remaining in the air and poor indoor air quality.
Filters need to be replaced on a regular basis. Over time, a filter becomes more and more loaded with particles of dirt and dust, making it more difficult for air to pass through the filter, and impacting resistance of air flow. Not only does a clogged filter raise operating costs, but it also decreases the quality of the air passing through the filter.
Finding a Balance between Efficiency and Energy
Before the escalating energy costs, finding a balance between proper filtration and reasonable operating costs wasn’t an issue. However, with expensive filters and even more costly energy bills, balancing indoor air quality and cost is vital to maintain a building and healthy occupants. One fortunate thing is that the range of available filtration systems has expanded over the recent years, offering solutions to fit every situation and can help meet both goals of proper filtration and cost efficiency.
There are many different types of filter designs such as traditional filters that trap particles between fibers, electrostatic filters that capture and hold particles with a charge, Filters with disposable or rechargeable containers to collect particles, or even ultraviolet based systems that help reduce concentrations of bacteria, viruses and fungus that might be in the air system. In order to select the best system for specific situations, it’s important to understand the types of contaminants found in a particular facility and the acceptable level of air quality for each application.
Most particulate contaminant in a building consists of dirt and dust particles, smoke, vapors, and bacteria. Particles are measured in very small metric units called microns. For example, dust and dirt can range from 10 microns to thousands of microns in diameter, where as smoke and bacteria range from .1 to 10 microns in diameter. The needs for each building will be different according to the amount and type of contaminants inside and around the space that will be filtered. Before selecting the right filtration system, building managers need to look for and eliminate sources of contaminants before looking for ways to filter them. Some common forms of contaminants include exhausts, chemicals, off-gassing from building materials, nearby loading docks, roads or dumpsters and other sources. After acknowledging and managing the unnecessary sources of contaminants, they need to determine the filters efficiency. Of course, it would be wonderful to remove every particle of contaminants; however, it just isn’t practical. Higher efficiency filters systems mean higher filter and energy costs. Research sufficient efficiencies for filtration systems so you can protect air quality with manageable maintenance costs to keep the system working the best it can. The overarching goal is to match a filter’s efficiency to the application’s needs to have the best scenario.