Yesterday was a beautiful spring day in Atlanta…during February.  With a high of 64, sunshine, and blue skies; made better by the arrival of outdoor furniture I had ordered before the holidays.  Today promises similar weather, followed by the return of cold & wet winter the rest of the week.

While we’ll enjoy another dinner on the deck this evening, we will then return indoors which are famously dry this time of year.  So why am I writing about humidity issues during the winter indoor dry season?  Because it is the perfect time to make plans for the upcoming 9 month season when our homes’ air is too wet.  Elevated indoor humidity makes your home feel warmer meaning you have to set the thermostat lower & raising your electric bill, allows allergens to grow such as dust mites, and can lead to mold and mildew.

The southern United States is known for its humidity, and no home in the South is immune from its wrath.  Whether you have an older leaky home, or a super airtight high-performance new build, humidity is a constant battle.  In leaky homes, dry conditioned air leaks out and is replaced by damp outside air.  In homes with a tight envelope, little air exchange means humidity gets trapped in your home from bathrooms, activities such as cooking, people breathing, and possibly from a basement or crawlspace.  

Let’s explore common ways humidity creeps into your home.  Homeowners in Atlanta LOVE basements, and our varied terrain means many of our homes have basements or crawlspaces.  These subterranean areas are prone to elevated moisture levels coming from the ground.  If not properly sealed (they usually are not), this moist air makes its way into your conditioned space.  This is why I recommend my clients with a basement, also run a dehumidifier.  Basements are an exciting addition for any home, (we love our home theater and arcade room!) but they require care to keep them enjoyable and safe. A majority of homes in the South also have HVAC ducts running through the unfinished attic or in a basement or crawlspace.  This ductwork is often leaky, letting the unconditioned and damp air, leak into your home.

But doesn’t running the AC dehumidify your home?  Yes, dehumidification is a byproduct of running your air conditioner, but it is not the main purpose.  When your home reaches the temperature set point on your thermostat, the AC unit turns off.  With our humid climate, this is usually before your air is dried to a desired point. If you have a smart thermostat such as Nest, you may have noticed a setting option “cool to dry”.  This option changes the focus of your home’s AC from cooling to dehumidifying, resulting in your unit continuing to cool below your set temperature.  This drastically increases your electrical usage, and can make your home cooler than you’d like.  Beyond comfort, if your home is too cool, it can increase the chance of condensation gathering in your walls and leading to other concerns.

More importantly, are the times we do not use air conditioning.  Though brief, we do have stretches in the shoulder seasons of Spring and Fall when cooling and heating are not needed.  Some simply open their windows, but this lets in further humidity and allergens. Then there is the Great Pollening in April where everything is covered in a layer of yellow/green dust.  During these times, a dehumidifier makes all the difference in home comfort.  Pay attention the next time your AC is not needed in the Spring or Fall.  Many notice increased sneezing and allergies resulting from elevated humidity, and the resulting increase in allergens.

Ultra-Aire Dehumidifier

Ultra-Aire Dehumidifier

So what’s a homeowner to do?  Install a dehumidifier.  While an easy route is to purchase a 50 or 70 pint portable dehumidifier for about $200 at the hardware store, the better permanent solution is installing a whole house dehumidifier. If you have a high-performance healthy home, your builder may have built above code and already included a whole home dehumidifier tied into your HVAC system.  But if you’re like me and living in an older home or most new construction, you have been relying on a portable unit, or 2 portable units in our case.

Let’s break down the scenario.  We live in a 1960’s ranch on a full basement which is finished, except for a small storage area under the laundry room and kitchen with a slab floor and block walls.  Since purchasing our home several years back, we had been running 2 portable dehumidifiers: 1 in the unfinished storage area and a second unit located in the mechanical room.  These two worked together to keep our humidity manageable, though not fully under control hovering around 55%.  Power consumption was roughly 600 watts each! It was adding a chunk to our electric bill and not fully maintaining our indoor humidity.  The humidity upstairs was also a concern.  During the summer we keep our thermostat between 74-76.  Because the AC was not overcooling our home, at times the humidity on the main floor would stay around 60%.

All of this combined to make the home feel stuffy in the summer, and cause allergy flare ups. It was time to get the humidity under control.  As part of our 2020 overhaul focused on improving comfort through conditioning our home’s air, our efforts led to installing a whole home dehumidifier.  I researched, got feedback from green builders in my sphere, and interviewed HVAC installers.  

PV HVAC Install

We ultimately landed on an Ultra-Aire 155H tied into our existing HVAC.  What a difference! Installed at the end of summer, we have been able to experience the improved air quality during the summer heat, the cool fall days we didn’t use AC, and even during heavy rains in winter. The improvements in comfort were immediate and impressive.  The controller is set to 45% humidity, which the unit has no difficulty maintaining. We placed hygrometers all over our home to measure the unit’s effectiveness, and found consistent measures throughout. While the unit itself uses just over 700 watts, it is drastically less than running both of the old units at 600 watts each. The unit dries the air more efficiently so it also runs for less time. And the AC?  With drier air, our home feels cooler allowing us to run the AC less, further reducing our electricity usage. Our allergies have drastically reduced. We only wish we had made the investment sooner.

Dehumidifier Installed

Ultra-Aire 155H Installed whole house dehumidifier

One word of caution.  There are many HVAC contractors, but far fewer that understand building science which is key to maximizing success with a whole home dehumidifier.  Indoor air quality and air conditioning are a science, and like all professions, not everyone does it correctly.  As a real estate agent, I encounter numerous homes with improper HVAC systems.  Items such as filtration and dehumidifiers are an additional layer, reliant on the basic system being designed well. Adding a whole dehumidifier is not cheap, so do not cheap out when installing.

If you have questions about controlling humidity in your home, feel free to reach out and chat or ask about our preferred contractor.