Best of Both Worlds: Balancing Energy Efficiency & Indoor Air Quality
It’s been well-established that the quality of our environment can make a significant impact on our health, both physical and mental. Factors like lighting, paint color, noise exposure and the presence of biophilia can all influence our stress levels, productivity and overall wellbeing. Even pre-pandemic, buildings that supported the health of occupants had emerged as a priority for owners and architects around the world.
However, designing a “healthy” building can sometimes be in direct contradiction to another major priority: energy efficiency. Optimizing indoor air quality, for instance, has become a top focus in the wake of the COVID pandemic. But while improving the quality and circulation of air can boost occupant comfort and wellbeing, it can also drive up energy costs.
Fortunately, air quality and energy efficiency can go hand in hand with the right equipment and methods. Here are some of the strategies we use at SHP to balance these priorities for our clients.
Increasing Ventilation Efficiency
Ventilation efficiency is all about how air is applied to a building and how it moves through the space—essentially, getting the most out of your fresh air. After all, having the technology to remove contaminants and bring air to an optimal temperature doesn’t mean much if it doesn’t reach occupants. That’s where an engineer’s design can save the day.
One way we boost ventilation efficiency is through displacement ventilation. This approach delivers ventilation air directly into the breathing zone, where it is then heated up so it rises up and away (along with contaminants). We’ve used this strategy on several projects like the Mt. Healthy Early Childhood Center. We can also use air temperature to improve ventilation; for instance, heating with air that is warm (but not hot) will mix better in a given space, as it isn’t hot enough to rise above the breathing zone.
Cleaning the Air You Have
Bringing in fresh air to a space is important, but cleaning the existing air first is a more energy-efficient way to boost indoor air quality. Choosing the right air filters is one way of accomplishing this; filters with a MERV rating of 14 or better can catch most particles and limit the spread of bacteria.
We’ve also used NBPI (needle-point bipolar ionization) technology, which produces an electronic charge to create a plasma field with positive and negative ions that can attach to pathogens and particles in a building’s ventilation system. NBPI can be applied upstream of cooling coils to prevent mold growth or on the supply air system to clean the air in your space—but it’s important to note that NBPI does have the potential to generate ozone and other potentially harmful by-products indoors unless specific precautions are taken in the product design and maintenance.
Another exciting development that has shown great promise is sorbent ventilation technology, which captures contaminants from indoor air and dispels them to the atmosphere. This approach allows for a much lower ventilation rate to be used to reach the desired indoor air quality, which reduces energy usage. While we haven’t used this technology at SHP quite yet, it’s something we’re prepared to implement if it makes sense for a project.
Recovering & Reusing Energy
Conditioning fresh air is one of the largest energy uses in a building’s HVAC system—but there are ways to capture and reuse some of that energy. Energy recovery ventilation (ERV) uses energy from a building’s exhaust air (air that would otherwise be “thrown away,” in a sense) to condition incoming air. While there are some instances where this strategy is required by code (ASHRAE Standard 90.1 lists minimum requirements for when energy recovery is required), our team always looks for opportunities to apply energy recovery even when it isn’t code-required—because it often just makes good financial sense for our clients!
Supplying Air Strategically
Another energy-efficient way to supply clean air to occupants is an approach called Demand Control Ventilation (DCV). This method is simple: Instead of conditioning air in spaces that aren’t being used, the system will only provide ventilation air when people are using the space. DCV considers how people are in the space, how it is being used, and how much fresh air is needed at that specific moment based on who’s in what rooms, and at what time. This approach is especially applicable for buildings like workspaces and offices that are largely empty in the evenings and on weekends. It improves indoor air quality for occupants while they’re in the space, but saves energy and money when the building is empty.
As technologies and ventilation strategies continue to improve, improving air quality and cutting energy costs don’t have to be an “either/or” decision for building owners. If you’re willing to invest in the right technologies, it is more than possible to create a space that is energy-efficient and healthy for building occupants.
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