What does crawl space ventilation mean to you?

Like so many things, crawl space ventilation can be interpreted in so many ways and those three words mean different things to different people. With such broad usage, there are so many different ways information about crawl space ventilation can be confusing or misleading. Let’s clarify what it means to ATMOX and in turn for your home. When ATMOX products are referring to “ventilation,” it is referring to the use of fresh air from the outside to reduce moisture and improve air quality.

Furthermore, ATMOX is specifically referring to mechanical ventilation with the use of fans for controlled air movement. We are not referring to passive ventilation where you just have openings for airflow. ATMOX also believes in the importance of air movement within a space. That’s what we refer to as circulation of air. We design and manufacture products specifically to address that as well.

Why is outside air important?

Indoor Air Quality (IAQ)

Indoor Air Quality has gotten lots of attention over the last few years, and the impact on human health should not be understated. There are several illnesses that have become more prevalent with poor indoor air quality. In extreme cases, it is sometimes referred to as “sick building syndrome.” According to the EPA, “Americans, on average, spend approximately 90 percent of their time indoors, where the concentrations of some pollutants are often 2 to 5 times higher than typical outdoor concentrations.”

The EPA goes on to state, “Indoor concentrations of some pollutants have increased in recent decades due to such factors as energy-efficient building construction (when it lacks sufficient mechanical ventilation to ensure adequate air exchange) and increased use of synthetic building materials, furnishings, personal care products, pesticides, and household cleaners.” These are self-induced problems. We are bringing more and more toxic chemicals into our homes. At the same time, we are compounding the problem by limiting the air movement and trapping the toxins.

The first important strategy to improve air quality starts with attempting to limit the source of pollutants in the home. After this step, the EPA suggests Improved Ventilation: “Another approach to lowering the concentrations of indoor air pollutants in your home is to increase the amount of outdoor air coming indoors.”

Crawl space effect on air quality

So how does this relate to the crawl space? Since most people are not frequently opening windows in their homes, outdoor air comes through infiltration in smaller openings and cracks between floors, ceilings, and windows in the home. Due to the stack effect, air generally rises bringing air from the crawl space into the living space. Exactly how much air is going up will vary widely depending on the tightness of the construction.

Let’s be clear – you can’t have true indoor air quality without exchanging the air with fresh outside air. There are many ways to accomplish this, but it doesn’t come from just circulating the existing air. You can achieve a target temperature or humidity level inside your home by using heating systems, air conditioning, dehumidifiers, and humidifiers. This will make your home very comfortable, but it doesn’t mean that you have actually achieved healthy “quality” air.

How do ATMOX products use crawl space ventilation?

The goal of ATMOX products is to create the best environment possible within the crawl space. We call it the ATMOXsphere. The ATMOX controller with sensors creates the ultimate solution for crawl space moisture issues and air quality concerns in any type of crawl space, regardless of whether it is more traditionally vented or encapsulated. The operating principle of ATMOX has always been to use the best atmospheric conditions to improve the crawl space. A component of this includes proper crawl space ventilation.

It’s easy to understand how fresh outside air will improve air quality as the musty stagnant crawl space air gets exchanged. However, outside air is also a powerful drying tool when used at the right times. The ATMOX controller uses sensors to get information on conditions both inside and outside and will only use crawl space ventilation with outside air when it will improve the crawl space. If that air is not available, the controller will wait for available air, or depending on setup will direct circulation fans or a dehumidifier to operate.

There is a lot of conflicting information on the use of outside air.

Over and over again, you can find websites stating that outside air is “bad” and that it won’t lower moisture in the crawl space. The problem is that this is true at times, but it is certainly not true most of the time. Just think about mother nature and the cycle of the world outside. It rains – trees and wood get wet – weather changes – air dries out the trees and wood – repeat. The outside air often dries out nature. It has the same capability inside a crawl space at times.

Geographic climates will vary. Over the course of a full year, the outside air is frequently drier than the air inside the crawl space. This is especially true during fall, winter and spring seasons. During the summer, the outside air is often hot and humid. Obviously, that air can certainly be “bad” for a crawl space. The key to using outside air for drying is to know when it is beneficial and only use ventilation during those times. That is exactly what ATMOX does.

Misconceptions of crawl space ventilation.

As mentioned above, whether you have a traditionally vented or an encapsulated crawl space, you need ventilation with fresh outside air to improve air quality. The ATMOX controller has settings for vented or closed crawl spaces to get that needed fresh air. It is also using that fresh dry air to reduce the moisture in the crawl space.

  1. There is no “good” dry air during the summer.
  2. Dehumidifiers can dry air more than outside air.

ATMOX focuses on dew point as it is a more accurate measure of actual moisture than humidity. (Humidity is obviously correlated, but the temperature component is critical to understand when there is available dry air.) Let’s look at some numbers to try to highlight the information related to the power of proper crawl space ventilation. First of all, dew points of outside air that are under 55 degrees make for a dry and pleasant day. Secondly, a dehumidifier can dry a space to a dew point of approximately 40 to 44 degrees.

A look at Atlanta, Georgia:

Everyone knows that southern climates have hot and humid summers. But do they still have dry air? It varies some from region to region, but let’s look at Atlanta, Georgia – a typical southern city. In a review of the AVERAGE dew points per month in Atlanta, the averages were lower than the dry 55 degree dew points during six months of the year. However, a crawl space only needs pockets of dry air to allow fans to push and pull air at the right times.

In looking at Atlanta again, in every month, the MINIUMUM dew point was 50 degrees or lower. This means that even in the peak summer months of June, July and August, there were times when the outside air was very dry. Then, if we compare the dew points of the outside air to a dehumidifier, the outside air was drier than the 44 degree dew point from a dehumidifier in nine months of the year. The outside air will dry more effectively than a dehumidifier during select times in nine months of the year in Atlanta. Learn more about dehumidifier usage in a crawl space. It is a powerful drying tool but is not energy efficient compared to the low electricity usage of ATMOX fans. Outside air is always more efficient in power usage. However, it is also the more effective drying tool during the majority of the seasons.

Limitations of crawl space ventilation.

The limitations of crawl space ventilation come into play when mother nature doesn’t cooperate for short periods of time. During those peak heat and humidity days that are typically only seen in select geographic areas, the ATMOX controller incorporates a dehumidifier effectively and efficiently when good outside air is not available to the crawl space. Your installer will work with you to determine the needs specific to your home. There is no one-size-fits-all crawl space solution, but with an ATMOXsphere, there is an ATMOX-products-improve-all crawl spaces solution.