The Health Window

Homeowners would be clamoring for humidity control equipment if they understood its importance to their health. So why do builders and contractors do such a poor job selling it?

by Brandon Glancy

Respiratory problems are least likely in a humidity range of 35-50%.
Source: American Society of Heating, Refrigeration and Air Conditioning Engineers

As sales trainer for a major HVAC equipment manufacturer, I give presentations on indoor air quality to builders and mechanical contractors around the country. Most of them assume that my sole topics will be ventilation and air filtration. While those are a huge part of what I cover, they're not the whole story.

By now, all builders should understand that good ventilation and filtration equipment is the only way to guarantee clean, fresh indoor air. That's true for any home, but it's especially true for a high-performance home that has been detailed to reduce natural air infiltration. I recommend an air cleaner with a MERV 16 filter, which captures 95% of particulates at .3 microns (hundreds of times smaller than a human hair). That filter will remove 99% of asthma and allergy triggers from the home.

But while it's easy to grasp the importance of ventilation and filtration, what few of the building professionals I meet seem to fully grasp is the relationship between health and humidity. When builders and HVAC contractors talk about humidity, they tend to focus solely on comfort. And they doubt that most customers will pay for humidification or dehumidification equipment.

My response is twofold. The first is that humidity has a big impact on human health, and contractors have a responsibility to help homebuyers understand that fact. Second, a good humidity control system will more than pay for itself in reduced heating and cooling bills. In my experience, most people in the industry do a poor job communicating these facts.

Understanding Humidity

We've all experienced the relationship between humidity and comfort. The higher the relative humidity (RH) at any given temperature, the warmer we feel—a hot/humid day feels more uncomfortable than a day that's merely hot. Conversely, the lower the relative humidity at any given temperature the less warm we feel.

There's also something called "the comfort window." This concept says that people will feel comfortable at relative humidity levels of 30 to 60% regardless of temperature. The comfort window is the optimum range for building materials—low enough to eliminate the chance of surface mold but high enough to keep wood from drying out and cracking.

Not surprisingly, the comfort window is also what I call the health window. From a medical standpoint, a 30-60% RH is the optimum range for human wellness.

The reasons are similar to why it's the ideal range for building materials. If humidity is consistently too high, you can expect to have mold spores in the air as well as on the bathroom ceiling. In addition, damp air is an attractive environment for bacteria viruses of all types to grow.

Excessively low RH is worse in many ways. If the air gets too dry, skin will dry and crack much like that of hardwood flooring. And dry skin—the body's first line of defense—will make it easier for bacteria and viruses to get absorbed into the system. You might assume that a dry environment will have fewer bacteria and viruses but if someone coughs or sneezes, whatever they put into the air will linger longer. Dry air can also cause breathing passages to constrict, making people with asthma more susceptible to an attack.

How Do You Control This?

The best way to ensure optimal indoor RH is with a whole-house humidifier or dehumidifier that has been integrated into the heating or air conditioning system. Each has a different sales strategy.

For instance, while Florida is known for being super humid, a dehumidification system might not be something homeowners think they need, as most of them depend on the air conditioner to dry the air. That's fine when it's 80 or 90 degrees outside, but when temperatures drop to the 70's, people end up walking around the house in sweaters. A whole-house dehumidifier can be integrated into the ductwork to keep the home dry but not cold during these times.

In dry regions, whole house-humidification can be a hard sell because people are used to portable units. Unfortunately, portable units are grossly inadequate.

Take the example of a typical Minneapolis residence on a 20-degree January day. The RH in that home will likely be in the 14-16% range, compared to 22% for Death Valley and 21% for the Sahara Desert. The Minneapolis home is the driest place on earth! The one or two gallons of moisture per day a portable unit vaporizes will hardly make a dent in the home's overall RH. (Have you ever seen someone bent over one of those portable units in a desperate attempt to get some moist air?)

Whole house systems by contrast can, depending on the size of the equipment, put between 18 and 40 gallons of water vapor per day into the home's air. That's more than enough to maintain healthy RH under the toughest conditions. For instance, I live in cold Wisconsin and my home's winter RH never falls outside the health and comfort window.

While health is a compelling reason for choosing whole-house humidification, homeowners still have to justify it financially. The beautiful thing is that, as mentioned above, the higher the RH the warmer we feel. A home that maintains RH within that window can be kept at a lower temperature than one with dry winter air, which of course means the home needs less heating energy.

At 70° F, for every 5% increase in RH you can lower the thermostat setpoint by 1° F without noticing any difference. On average, a 1 degree setpoint reduction will cut the heating bill by 4%, so if customers raise RH from 15% to 35%, they can save 16% or more on their heating costs while enjoying more comfort and better health. In fact, my company has calculated that an evaporative humidifier can pay for itself in as little as five years.

Selling Well-Being

Although these advantages create strong potential demand for humidity control equipment, contractors aren't capitalizing on that demand. Our research has determined that 60% of salespeople drop the conversation about humidity control the first time they sense any resistance from the homeowner. That's why the builders we know who spec the most humidity control equipment make it a standard in their homes.

But even builders who make this equipment standard have to answer questions from homeowners about why the equipment is needed, and why it's worth the cost. Those builders need to educate homeowners on how this equipment pays them back in dollars as well as in health and wellness.

Sales training is a separate topic, and one that I cover in my presentations. The major equipment manufacturers all want to help their builder clients with this—after all, it's in their interest for you to spec their equipment. As an added resource, my company has created the Aprilaire Healthy Home App, which includes video presentations about healthy home systems that the builder's sales staff can show to homeowners. We created it in partnership with a builder who wanted to mount an iPad on the wall during the Parade of Homes.

One final note. Fresh air and humidity control systems need to be maintained and monitored to ensure that they do their job over time, and that means orienting homeowners on how to work the controls and when to schedule maintenance and repair. That's another place your equipment manufacturer can help. Most have teams dedicated to helping builders and are happy to work with customers on how to orient homeowners. Take advantage of them.o

Brandon GlancyBrandon is the corporate sales trainer for Aprilaire


Erik Straite
View User Profile for Erik Straite

re: Adding humidity in dry climates

Monday, April 20, 2020 10:15:28 AM

Great article! Do have any data or research on how much the savings on heating bills are offset by increases in water bills in a dry climate where homes need to increase the humidity? Is it still a net savings?

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