Air quality is one of those things most of us don't think about until we have a negative experience. Air in a home is just air until we smell dampness or our allergies kick in. With so many people working from home, paying attention to air quality has become even more critical.
Nowhere is that truer than when thinking about renovating basement space. Poor ventilation can lead to stale air, humidity buildup, and potential health hazards, including the inhalation of volatile organic compounds (VOCs), mold, mildew, and pet dander.
With advances in home energy efficiency come some unintended consequences. HVAC systems work efficiently to maintain a comfortable temperature in the home. Windows and exterior doors have tight seals. Walls and ceilings are insulated with excellent R-value. So, instead of opening windows to get airflow, windows stay closed most of the time.
Air quality concerns are most acute in the subterranean space of the basement. Damp air that is not moving makes for space no one wants to spend time in. Especially in a basement, it takes more than just a standard HVAC system to maintain good air quality.
When it comes to air quality, your nose doesn't always know what it's smelling. Air needs to be tested to make sure the basement is a healthy and habitable space. There are two main concerns to test for: radon and humidity.
Radon is a cancer-causing substance, so your basement should be tested for radon levels and mitigated if necessary. Inexpensive radon tests are readily available.
A basement with a high level of humidity becomes a breeding ground for mold and mildew spores. If you have allergies, you want to avoid mold and mildew. Humidity can be monitored using various tools available at different price points. To measure air quality for radon, humidity, and more, you can install a top-tier air quality monitor like this one.
Unfinished basements in New England typically feature small transom-size windows and, often, a steel cellar door leading up some steps to the yard. Installing full-size doors or windows in the basement goes a long way toward improving ventilation.
An HVAC system is not designed to operate in an unfinished basement. Typically, unconditioned basements are often damp. The challenge is to seal a basement from moisture while allowing for airflow. When planning a basement renovation, addressing water infiltration is the first step. This might mean installing new rain gutters outside. It might mean grading the ground around the perimeter of the home so water flows away from, not into, the basement.
Who doesn't remember the old-school dehumidifier? You may still be using this in your basement. Here's why these machines with a bucket collecting water are not the ideal solution. When you try to capture moisture in the air and collect it in a bucket, you are just concentrating the moisture in one spot. Sure, you remove what is in the bucket when it is full, but then it fills up again. Moisture is still sitting there in the room.
Fortunately, some systems reduce humidity and create excellent ventilation for basement spaces. It's all about air exchange. Air exchange systems need to be sized based on formulas related to the square footage, which in turn determines cubic footage. Your design-build partner should understand the codes for your New England municipality as they relate to the air exchange formula required for your basement.
It might sound like a complicated medical device (and it’s certainly good for your health), but an energy recovery ventilator (ERV) is one of the best ways to maintain healthy indoor air in New England’s climate. Several manufacturers offer excellent systems; for example, Panasonic makes ERVs designed for balanced ventilation and energy efficiency.
An Energy Recovery Ventilator (ERV) is designed to continuously bring fresh air into your home while removing stale indoor air. It operates using two separate air streams:
Inside the ERV, these two airflows pass through a specialized core that allows them to exchange heat and moisture—without mixing. This energy exchange tempers the incoming air, meaning it’s pre-warmed in winter and pre-cooled in summer using the outgoing air’s energy. The system also manages indoor humidity by transferring moisture between the airstreams as needed.
The result? Fresh, filtered air enters your home at a temperature and humidity level closer to your indoor conditions, reducing the workload on your HVAC system and improving overall air quality and comfort.
If you have an HVAC system in the basement, you can attach the ERV to the HVAC or integrate it with the new system. An ERV operating in the basement can also help keep humidity down on your first floor as well. ERV pre-filters need to be changed regularly.
The ERV will monitor air flow and shut down when the pre-filters need to be changed. ERV’s also have a primary HEPA filter that is also monitored and will eventually need replacement. Changing the pre-filters as needed will extend the life of the HEPA filter. The ERV is the primary tool, but you still need to monitor humidity levels. If humidity levels are not where you need them, you should consider other humidity management systems. Mini-split systems can be set to dehumidify without conditioning the air, pumping the moisture outside. Be aware that a mini-split system is a hybrid air conditioning system that does not filter the air.
Ventilation and air quality are essential considerations when renovating basement space. Testing for radon and humidity is the first step. Even unfinished basements should be tested for radon.
When the sources of moisture are remediated, and a quality air exchange system is installed, the basement becomes a welcoming space instead of an afterthought.
To learn more about the basement remodeling process, please read our eBook, “The Expert Guide to Luxury Basement Remodeling for Discerning Homeowners” And if you are ready to speak about your project, please schedule a home renovation discovery session.