The Truth About Cooling Your Home: Whole House Fans vs. ERV/HRV Systems
One of the most prevalent misconceptions in the field of building science today revolves around the effectiveness of Energy Recovery Ventilators (ERV) and Heat Recovery Ventilators (HRV) in cooling your home. Many homeowners believe that these systems can efficiently cool their living spaces and save them money on air conditioning expenses. In this blog post, we will debunk this myth and shed light on the true capabilities of ERV/HRV systems compared to a more cost-effective and efficient alternative: whole house fans.
What Are ERV/HRV Systems?
Before we delve into the misconceptions, let’s clarify what ERV and HRV systems are. ERV stands for Energy Recovery Ventilator, while HRV stands for Heat Recovery Ventilator. These systems consist of small fans designed primarily to circulate a minimal amount of air. While ERV/HRV systems are indeed effective for improving indoor air quality, many homeowners mistakenly assume they can also assist in cooling their homes and reducing air conditioning costs.
In reality, ERV/HRV systems are specifically engineered for homes in regions with poor air quality. Their primary purpose is to enhance indoor air quality rather than to provide effective cooling or energy savings.
Inadequate Air Movement
To understand why ERV/HRV systems fall short in the cooling department, let’s examine the numbers. Air movement is quantified in cubic feet per minute (CFM). A typical home equipped with an HRV or ERV system is sized to handle approximately 150 CFM. In contrast, a whole house fan can move up to a whopping 7,000 CFM!
To put it into perspective, one whole house fan is equivalent to over 40 HRV/ERV systems. Whole house fans can rapidly replace warm indoor air with cool outdoor air, offering comprehensive ventilation and a refreshing breeze throughout your entire home. With a properly sized whole house fan, you can achieve a complete air exchange in less than 4 minutes.
In stark contrast, ERV/HRV systems, with their 150 CFM capacity, would require over 2 hours to accomplish the same air exchange in your home. Clearly, these systems are inadequate for effective cooling.
Now, let’s consider the cost factor. ERV/HRV systems are known for being prohibitively expensive for the minimal benefits they provide. On average, installing one of these systems can set you back two to three thousand dollars. However, the functionality they offer is comparable to that of a large bathroom fan.
In contrast, whole house fans are not only more cost-effective but also exceptionally energy-efficient. The average cost of a whole house fan is less than $1,500, and they operate at a fraction of the cost, consuming only pennies per hour. Additionally, whole house fans address the three primary issues of home ventilation and cooling: they enhance comfort, reduce AC-related expenses, and improve indoor air quality.
When it comes to efficiently cooling and ventilating your home, the choice between ERV/HRV systems and whole house fans is clear. ERV/HRV systems, with their limited air movement and high costs, cannot effectively cool your home or provide substantial energy savings. In contrast, whole house fans offer a cost-effective solution that not only cools your home efficiently but also enhances comfort and indoor air quality. It’s time to dispel the misconceptions and opt for the practical advantages of whole house fans.