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Last Revised: 11/22/2024
Have you noticed more allergies or respiratory issues without an increase in time spent outside?
In recent years, the public has become aware of the significance of our home’s indoor air quality (IAQ) and its impact on our health. This impact has only grown, as working from home has become increasingly common.
In fact, most people spend about 90% of their time indoors and receive 72% of their chemical exposure in their own homes, according to the Environmental Protection Agency (EPA).
Air-sealing practices (like improved insulation and caulking) are on the rise as homeowners have sought ways to improve the energy efficiency of their homes. But this has led to an unwanted problem: the accumulation of pollutants and allergens within our home.
It shouldn’t come as a surprise that introducing fresh air to an indoor environment will improve air quality. However, it’s not always as simple as opening a window – outdoor weather conditions must be just right to rely on this strategy.
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The HVAC experts at Mattioni are at the forefront of installing the fresh air ventilation (FAV) systems. These systems create healthy home environments by significantly improving IAQ and reducing respiratory diseases, allergies, and other adverse health effects.
Yet homeowners interested in investing in the health of their home’s air supply are often confused when evaluating which fresh air ventilation system to install.
That’s why we put together this article; to outline the different fresh air ventilation systems and strategies from top to bottom. This will help you understand why some strategies are better than others.
After reading this, you’ll know what HVAC professionals consider to be good, better, and the best whole-home ventilation strategies and why.
“Limited” Fresh Air Ventilation Strategies – Simple Steps that Fall Short in Impact, Control and Efficiency
Before we get into some of the more effective strategies, let’s start with a couple of common ventilation methods that can marginally improve your indoor air quality. These are ultimately not very effective at controlling your home’s atmosphere.
Passive Ventilation
Passive ventilation refers to the natural movement of air into and out of your home without mechanical assistance. This strategy relies on uncontrollable air sources such as drafts, cracks in the structure, or simply opening windows.
How it Works: Air enters through openings in the structure, moving in response to changes in temperature, pressure, or wind.
Challenges: Passive ventilation is highly dependent on outdoor conditions like temperature and humidity. For instance, in a tightly sealed modern home, passive airflow is often so low that adequate airflow is highly unlikely to be achieved.
New vs. Old Homes: Older homes tend to have higher air exchange rates due to their less airtight structures. New homes are designed to be energy-efficient and tend to have lower natural air exchange, which can lead to poor ventilation.
While passive ventilation is better than having no ventilation at all, and can be improved by taking steps such as placing a fan near a window, it provides little to no control over the air quality entering your home.
Negative-Pressure Ventilation (Powered)
A step above passive ventilation (but not quite a good solution) is implementing a negative-pressure (exhaust-only) system in your home. These systems use powered exhaust fans to remove stale air from the home, but they don’t control the source or quality of incoming air. These systems depend on your home’s structural tightness to draw in air, making them inconsistent in performance from home to home.
Installation: Commonly installed by electricians or roofers (instead of HVAC specialists), these systems are often found in new homes due to their relative simplicity and low cost.
How it Works: Exhaust fans or hoods pull air out, creating a vacuum that pulls fresh air in through cracks and gaps in the structure.
Limitations: Since the incoming air isn’t filtered or tempered (heated or cooled), this strategy can potentially bring in new pollutants or allergens and can significantly hinder your home’s energy efficiency.
Key Advantage: Negative-pressure systems are relatively affordable and simple to install but offer limited control over air quality and energy efficiency.
A “Good” Fresh Air Ventilation Strategy – More Control & Air Filtering
While passive and negative-pressure ventilation systems fall short in a few ways, here is a system that’s a step better.
Positive-Pressure Ventilation (Unpowered)
Positive-pressure ventilation is an improvement from negative-pressure systems since they actively push fresh air into the home while passively exhausting stale air. Though unpowered, it’s a step toward more controlled air quality management.
How it Works: Fresh air is drawn into the return side of your HVAC system’s ductwork through a duct extending to your home’s exterior. A mechanical damper controls the airflow, which is supported with your HVAC system’s existing blower.
Features:
- Air coming into your home is filtered, but still untempered. This means it won’t bring pollutants into your home but it’s affected by outdoor weather conditions (temperature and humidity).
- By positively pressurizing your home, this system forces stale air out through leaks and gaps in the structural tightness which prevents contaminants from entering.
Pros: Positive-pressure ventilation ensures that only fresh air enters the home and filters out all external contaminants. Although, they don’t offer precise control over temperature or humidity.
Systems Available to Install: The Aprilaire 8126 ventilation control system is available, and costs around $2,000.
A “Better” Fresh Air Ventilation Strategy – A Jump to Higher Efficiency Levels
Now let’s explore some of the upper-tier fresh air ventilation strategies, capable of thoroughly and consistently creating a healthy home environment.
Positive-Pressure Ventilation (Powered)
A powered positive-pressure system adds mechanical assistance to the process, with its own blower motor, improving energy efficiency and offering more control compared to the unpowered option.
How it Works: Very similar to the unpowered system, fresh air is pulled into the HVAC return duct, but this system uses its own blower motor to better control the timing and volume of air entering.
Advantages:
- Allows you to set when the system automatically activates, based on factors like outdoor temperatures or time of day.
- Paired with a filter to improve indoor air quality, making it compatible with Energy STAR systems.
- More efficient than relying solely on the HVAC blower, especially compared to those that rely on a lower-end HVAC system.
Efficiency: This system can help manage indoor air quality more consistently, though it still relies on outdoor conditions and has no temperature regulation.
Systems Available to Install: The Aprilaire 8145 ventilation system is available to purchase and install with an HVAC professional. It costs around $3,000.
“The Best” Fresh Air Ventilation Strategy – Maximizing Efficiency & Control
Here is what is widely considered to be the most effective whole-home fresh air ventilation system.
Energy Recovery Ventilation (ERV) Systems – Balanced-Pressure
At the top tier of whole-home fresh air ventilation strategies is the energy recovery ventilation (ERV) system, considered the best option by HVAC professionals. It’s designed to balance the intake and exhaust airflow and regulate incoming air temperatures with a heat exchanger. This component helps the energy efficiency of the system and prevents the incoming air from being a drag on your home’s temperature.
How it Works: In the summer, this system uses the stale, conditioned indoor air you’re expelling to cool the incoming hot air. In the winter, it uses the stale, heated indoor air you’re expelling to preheat the incoming cold air.
This feature is significant to maximize your home’s comfort, especially in climates with extreme temperatures.
Benefits:
- Provides fresh, filtered air without introducing temperature swings, making it a more energy-efficient option than other strategies.
- Since the system is balanced, results are consistent across different homes.
Systems Available to Install: The Aprilaire 8100 energy recovery ventilation system (ERV) is available and costs around $6,000.
Whole-Home Dehumidifiers: Support any FAV System
It’s worth pointing out that regardless of which system you choose, pairing it with a whole-home dehumidifier will improve both comfort and efficiency.
Whole-home dehumidifiers help maintain ideal humidity levels throughout the hottest parts of the year. When paired with a ventilation system like an ERV, you’ll experience the best of both worlds and a significantly more comfortable, and healthy, home.
Which Whole-Home Fresh Air Ventilation Strategy is for Me?
If there were a way to lay out an exact plan that dictates what you need to do next in this process, that would be phenomenal. But the reality is that only you know what is best for your home and your situation.
So, what can you do? Our advice is to take everything in this article and see which system applies most closely to your situation.
If you’re after a top-of-the-line system that’s going to give you the best ventilation results, and short-term budgeting is less of a priority, then an ERV is the best choice for you.
And if short-term budgeting is more of a factor, but you still want to do something about your indoor air quality, then looking into some positive-pressure FAV systems likely makes sense for you.
Either way, becoming fully informed on fresh air ventilation systems is the best way to ensure that you end up with the right system in your home.
Don’t be afraid to take any of your questions to your HVAC professional before undergoing a system installation.
To speak with our friendly staff about the risks of poor indoor air quality and which solution can give you the best result, call (610) 400-8510. Or schedule an appointment online.
Don’t wait for another season of poor indoor air quality – upgrade yours today.
