Radon mitigation lives at the intersection of health protection and building science. At Air Sense Environmental, we spend our days balancing two priorities that sometimes pull in opposite directions: drive indoor radon as low as reasonably achievable, and do it with a radon system that sips electricity, not gulps it. If you own a radon mitigation system or you are considering one for a home in the St. Louis area, knowing how airflow, pressure, materials, and controls interact can trim energy use without sacrificing safety.
This guide distills what we have learned from hundreds of installations and tune ups across a variety of foundations, from mid century basements in Richmond Heights to crawlspace homes near the Meramec. It covers where the energy goes, what you can and cannot change, and the practical steps that deliver payback.
The physics behind energy use in radon mitigation
Most residential systems use active sub slab depressurization. A fan pulls air from beneath the slab through a suction point and exhausts it above the roof. By keeping pressure slightly lower under the floor than indoors, soil gas gets captured before it enters the living space. That fan runs continuously, which is why efficiency matters.
The electrical load depends on airflow against resistance. Think of the system as a loop: soil and aggregate under the slab, suction pit, horizontal pipe runs with elbows, vertical stack to the roof, and a discharge into the wind. Every section adds friction. Fan manufacturers publish performance curves that show how many cubic feet per minute a model will deliver at a given pressure. A tight soil like clay, common around St. Louis, demands higher static pressure than free draining gravel. If the house has a thick slab and no underslab aggregate, the fan may need to work harder to reach far corners. Add long horizontal runs or too many 90 degree elbows and the pressure climbs again, which pushes you to a bigger fan and more watt draw.
There is also the matter of stack effect and seasonal changes. In winter, warm indoor air rises and escapes, pulling in makeup air from the lower levels. That tends to boost radon entry, which means the mitigation fan may need to move a little more air to hold the same indoor level. Frozen or saturated soils around the perimeter can raise resistance under the slab. A well planned system anticipates these swings so you do not end up oversizing the fan in July and wasting energy for the other eleven months.
Where the kilowatt hours go
A typical radon fan for a single family home draws 15 to 90 watts. Over a year of continuous operation, that translates to roughly 130 to 790 kilowatt hours. Local electric rates determine dollars, but a common St. Louis residential rate in recent years has floated around 12 to 14 cents per kilowatt hour. That puts annual fan costs in the range of 15 to 110 dollars for most systems. Add a little for any heat loss through the vent piping if the run is inside the thermal envelope.
Design decisions at installation time dominate the long term energy profile. After that, maintenance and small optimizations keep you from drifting upward. The path to efficiency, then, starts before the concrete dust settles.
Designing for low energy draw without losing radon control
Good design shrinks static pressure wherever possible. The result is a fan that can do the same job at a lower wattage. A few field tested principles consistently pay off.
Right size the suction pit. Creating a properly sized suction pit beneath the slab, typically 10 to 20 inches in diameter and a few inches deep depending on slab thickness and aggregate, lowers the localized resistance and lets pressure propagate across a larger area. In homes with tight soils and no gravel, we often expand to an oval or a pair of connected pockets. A too small pit traps the system in high pressure mode, which forces a beefier fan and raises noise.
Minimize pipe friction. Horizontal pipe runs should be as direct and short as the layout allows. Every 90 degree elbow adds equivalent length, and flexible sections or corrugated drain tile above grade create turbulent losses that compound quickly. We prefer smooth schedule 40 PVC, well supported, with long sweep fittings instead of tight 90s when space allows. In many St. Louis basements, we can route straight to an exterior riser within 15 to 25 feet of pipe. That difference alone often lets us step down one fan size.
Seal thoroughly. Air the fan moves should come from under the slab, not from the basement. We seal cracks, slab penetrations, and the slab to wall cold joint with polyurethane or appropriate caulk. We also seal sump lids with clear access ports and gaskets. Better sealing reduces the amount of conditioned indoor air that the system could accidentally capture, which protects your heating and cooling efficiency and often allows a smaller fan to hold the same under slab vacuum.
Plan the discharge wisely. A vertical exhaust that clears the roofline by at least the local code requirement and terminates in free air avoids wind-driven backpressure and keeps radon away from windows. Horizontal sidewall terminations can be convenient, but in our climate the plume can hug the house in calm, cold conditions. That can force higher flow to meet indoor targets or raise re-entrainment risk. When we do use a sidewall discharge, we increase separation, add a stack extension, and verify with post mitigation tests in several weather conditions.
Match the fan to the job. Two homes can look identical and need different fans based on under slab conditions. Fan models vary widely in watt draw, pressure capacity, and noise. A common mistake is installing a high pressure fan by default. It will certainly reduce radon, but it may cost twice the electricity needed. We start with diagnostic measurements, such as pressure field extension tests using a vacuum applied through a pilot hole, then choose the smallest fan that maintains coverage. Where the basement footprint is segmented by footings or additions, we sometimes split the system into two smaller fans rather than one large one. Counterintuitively, two efficient fans at low load can draw less combined power and run quieter than a single high pressure unit forced to fight poor connectivity.
What we see in St. Louis foundations
Soil and building stock matter. In the St. Louis region, many homes sit on dense clay with pockets of fill near additions. On pre 1970 homes, underslab gravel is hit or miss. Even when gravel exists, it might not communicate well across the slab because of interior footings or settling seams. Split level homes and tuck under garages add complexity.
Those conditions tend to push systems toward higher static pressure. To keep energy in check, we do more groundwork during installation. We core the suction pit slightly larger, create cross connections under the slab when additions have separate pours, and pay extra attention to sealing the cold joint. We also watch the sump carefully. Many older basements rely on a sump for drain tile that only serves half the perimeter. Tying directly into that line can steal air from the basement through the sump if the lid is not sealed and the drain caps are not tight. A sealed sump with a balanced bleed from the drain system, not a wide open connection, gives you the airflow you want without depressurizing the basement.
On crawlspaces, we use a reinforced membrane over the soil, seal to the walls, and maintain a modest vacuum under the liner. The choice of liner thickness and tape matters. A flimsy liner that develops pinholes makes the fan work harder over time and can pull odor and moisture into the crawlspace. That is a double hit, more electrical use and more dehumidification load for your HVAC.
The HVAC connection: avoiding energy penalties
A radon mitigation system interacts with your heating and cooling whether you notice it or not. If the system unintentionally pulls conditioned air from the house, your furnace or air conditioner runs longer to replace that lost energy. A well built system takes air from the soil and returns it outside, not from the basement. That is where sealing earns its keep.
We also pay attention to the location of the vertical riser. Running warm, moist indoor air across a cold pipe in winter can cause condensation. If that pipe runs through a closet or chase, the moisture can feed mold. Insulating interior pipe sections in unconditioned or semi conditioned areas reduces both heat loss and condensation risk. Where the pipe is entirely outdoors, proper supports and a color that limits solar gain help keep the fan stable in summer.
Make up air is another subtle factor. Strong bath fans, range hoods, and fireplaces can depressurize a house. Combine those with a radon fan that leaks at the slab and you can pull more air from the living space than you intend. During commissioning, we check building pressure under common scenarios, like clothes dryer on, bath fans running, and a kitchen vent set to high. If we measure a significant negative indoor pressure, we track down leakage paths and fix them. The goal is neutrality: let the radon system do its job under the floor while the house stays near balanced pressure.
Monitoring and controls that protect both safety and efficiency
Once a system is up and running, the best way to avoid drift is to measure and verify. Old school manometers give a simple visual, but they only show fan suction, not radon levels. We prefer a combination of instruments: a pressure gauge for quick checks, plus periodic radon measurements, either continuous or at least annual short term tests during different seasons.
Smart plugs and timers rarely make sense for radon fans. Cycling the fan off to save a few cents can allow radon to surge inside, and it takes time to pull levels back down. Instead, if you want active control, choose a fan with an efficient motor and consider a speed controller that is designed for that fan model. Some brushless DC fans support variable speed without the hum and heat of old rheostats. We set the speed to maintain a healthy margin below the EPA action level across seasons, not just on a mild day in April.
If the home has a building automation system or a security panel with auxiliary inputs, we sometimes tie in an alarm for fan failure. That does not directly save energy, but it prevents the common problem of a silent failure that goes unnoticed for months, followed by a hasty replacement with an oversized fan. Catching problems early lets you repair or swap with the same efficient model instead of sliding into a quick fix that costs more to run.
Maintenance that pays for itself
Most radon fans run for 5 to 10 years. Some go longer, but performance can fade before they fail. Bearings wear, impellers accumulate dust, and vibrations loosen joints. Small losses add up.
An annual walkthrough takes less than an hour and keeps the system at its design point. We start with a sound check at the fan and the discharge. A change in pitch often signals a bearing on its way out. We inspect the pipe supports and all visible joints for hairline cracks. We look at the manometer or digital pressure reading and compare it to the original baseline. If suction has crept up without any change in radon levels, airflow likely dropped and the fan is working harder than it should. We also confirm that sump lids, membrane seals in crawlspaces, and slab crack seals remain intact.
Exterior sections deserve a close look. UV breaks down PVC over time, especially elbows and fittings with thinner walls. We touch test the pipe for brittleness and check brackets. On shaded north walls, algae can build up around joints and hide a slow leak. Cleaning and resealing costs little and restores performance.
When a fan needs replacement, we do not default to a larger model. We review the original diagnostics and measurements, retest if needed, and select the smallest fan that meets the radon target with margin. Manufacturers occasionally update internals, so a current model with similar curve might draw fewer watts than the unit installed eight years ago. That is an easy win.
Case examples from the field
Clayton basement with segmented slab. A 1930s brick home had an addition that created a second slab separated by a footing. Initial mitigation used a single high pressure fan at 85 watts and one suction point on the older slab. Radon dropped to safe levels in summer but crept up in winter, and the fan noise echoed in the mechanical room. We cored a small crossover under the footing to connect the two slabs, enlarged the suction pit, and swapped the fan to a mid pressure unit rated at 45 watts. Winter radon held steady below 2.0 pCi/L, and the homeowner saw about 45 dollars per year savings on the electric bill relative to their rate.
Crawlspace near Webster Groves. The house sat on a vented crawl with plastic sheeting loosely laid over soil. A radon fan pulled hard through leaks in the liner, drawing cold air into the living room through the floor. The heat pump ran constantly on winter mornings. We replaced the liner with a 12 mil reinforced membrane, sealed to the walls, and taped around every pier. The same fan, dialed down on a compatible speed controller, maintained 0.5 to 1.0 Pa under the liner and indoor radon stabilized under 2.5 pCi/L. The homeowner reported shorter heat pump cycles and a quieter fan. Watt draw dropped from 70 to about 40.
South County ranch with long pipe run. The only practical route to the exterior required a 40 foot horizontal run with several turns. The original installer chose small diameter pipe to hug the joists, which forced a large fan. We re routed with 3 inch pipe, replaced two tight 90s with long sweeps, and supported the run every 6 feet. The system moved the same air at a lower static pressure, which allowed a switch from a 90 watt fan to a 55 watt model. Indoor levels improved slightly, and the fan tone softened.
When lower energy is not the right call
Every so often we find a house with such tight soil, multiple slab breaks, or a complicated foundation that efficiency improvements would risk radon control. In those cases, we explain the trade off and prioritize safety. If radon sits near 10 pCi/L before mitigation and the foundation offers poor communication, taking it under 2 pCi/L may require a stout fan and meticulous sealing. We still look for friction reductions and leak sealing, but we do not chase watt savings that erode the health outcome. For most homes in the St. Louis area, though, thoughtful design yields both low radon and reasonable energy use.
What you can check today
Homeowners often ask what they can do without crawling through joists or learning fan curves. A few simple checks make a difference. Keep an eye on your system’s indicator, whether a U tube manometer or a digital gauge. If the reading drops to zero, the fan likely failed. If the reading climbs well above its normal baseline, a discharge blockage or frozen condensate could be at fault. Seasonal radon testing, one short test in winter and another in summer for the first year after installation, gives a fuller picture than a single post install test.
If you have a sump, look for gaps around the lid, missing gaskets, or loose cleanout caps. If the system relies on a Radon mitigation contractor crawlspace membrane, scan for rips and tape that has pulled away at seams or piers. On the exterior, glance at the discharge to make sure it is clear and that the vertical pipe is firmly supported. These small observations help your radon mitigation contractor decide whether a tune up can bring the system back to its intended efficiency.
The role of testing in efficiency decisions
Energy optimization without data can backfire. Lowering fan speed to save electricity only makes sense if indoor radon stays low across weather swings. In our practice, we pair any fan adjustment with measurement. We like to see a two week dataset that spans a few fronts and temperature changes. Continuous monitors provide that detail. If the average remains well under the action level and peaks stay modest, we keep the setting. If peaks jump during inversions or deep cold snaps, we restore speed and look for ways to improve pressure field extension or reduce leakage rather than accepting a marginal result.
Longer term, an annual or semiannual test documents performance drift. Fans age, soils settle, and homeowners remodel. A new basement bedroom with tighter windows can change how air moves. A bathroom remodel can add an exhaust fan that tips the pressure balance. Testing catches these changes before they turn into problems.
Costs, savings, and realistic expectations
Efficiency improvements fall into three buckets. First, choices at installation that carry little or no extra cost: better sealing, thoughtful pipe routing, proper pit sizing, and fan right sizing. These steps often produce the majority of your lifetime savings. Second, mid cost upgrades that may apply when retrofitting an older system: swapping tight 90s for long sweeps, upsizing a constricted pipe section, adding insulation in a cold chase, or replacing a worn fan with a more efficient model. Third, major changes such as adding a second suction point or coring a crossover under a footing. Those carry higher labor costs but can enable a smaller fan and a quieter system with better margins.
On average, shaving 20 to 40 watts from a continuously running fan saves roughly 20 to 50 dollars per year at common local rates. Over a seven to ten year fan life, that accumulates to a few hundred dollars, not counting any HVAC savings from reduced unintended air capture. That may not sound dramatic, but combined with better comfort and noise reduction, it justifies careful design.
Selecting the right radon mitigation contractor
Skill and judgment matter as much as hardware. If you are searching for a provider by typing radon mitigation near me, look beyond the first ad. Ask how they diagnose under slab conditions, whether they perform pressure field extension tests, and how they decide on fan size. A reliable radon mitigation contractor should be willing to explain why a certain model fits your home and what they have done to keep static pressure low. In the St. Louis market, you will find a range of approaches. Some firms standardize on a single high pressure fan to get fast results. Others, including Air Sense Environmental, invest an extra hour on layout and sealing because it pays off over the system’s life. If you see references to StL radon or St Louis radon services, skim their project photos for clean pipe runs, sealed sumps, and roof terminations that clear windows. Those details hint at energy awareness.
A short homeowner checklist for an efficient, safe radon system
- Confirm your fan’s normal suction reading and write it on a label near the gauge. Test indoor radon twice in the first year, winter and summer, then annually. Inspect and reseal sump lids, slab cracks, and crawlspace membranes as needed. Keep the discharge clear of obstructions and ensure pipe supports are solid. Call your contractor if the fan tone changes, suction reading drifts, or tests rise.
When to revisit your system design
There are moments in a home’s life when it makes sense to reassess the radon system. If you finish a basement, add egress windows, or dig a new footing for an addition, you likely change air pathways under the slab. If you swap windows and tighten the envelope, stack effect and ventilation patterns shift. If you convert a vented crawl to encapsulated, you fundamentally alter how the mitigation system should operate. These changes are prime opportunities to refine the system and capture energy savings that were not practical before. We frequently pair these projects with a pressure retest and, if useful, an adjustment to fan speed or a small piping upgrade.
Practical advice for cold snaps and storm seasons
Deep winter in the St. Louis area brings polar air and frozen ground. A poorly sloped exterior run can collect condensate that freezes and partially blocks the pipe. When that happens, suction rises, watt draw follows, and radon can climb. A simple, sustained downward slope to the fan housing, drip legs where needed, and, in some designs, a small condensate bypass hole above the fan help prevent freeze related energy spikes and failures. After heavy spring rains, saturated soils can temporarily raise resistance. If your system was designed with tight margins, you may see radon blips. Good design anticipates those weeks and leaves headroom, which again allows the fan to run in its efficient zone the rest of the year.
The bottom line for homeowners in the St. Louis area
An efficient radon mitigation system does not happen by accident. It comes from good diagnostics, tidy routing, careful sealing, and a fan chosen to meet your home’s actual needs. The payoff is steady, low indoor radon with quiet operation and modest electricity use. Whether you are installing a new radon mitigation system or living with one that has been humming for years, a small amount of attention goes a long way.
If you are evaluating options for radon mitigation St Louis or searching Stl radon services to compare quotes, ask contractors to talk specifically about energy and airflow, not just the post install test result. And if you already have a radon system that seems louder than it should or costs more than expected to run, a focused tune up can often reclaim both comfort and efficiency. At Air Sense Environmental, we like to leave homes with radon levels low enough that families stop worrying, and systems efficient enough that they forget the fan is even there.
Air Sense Environmental – Radon Mitigation & Testing
Business Name: Air Sense Environmental – Radon Mitigation & TestingAddress: 5237 Old Alton Edwardsville Rd, Edwardsville, IL 62025, United States
Phone: (618) 556-4774
Website: https://www.airsenseenvironmental.com/
Hours:
Monday: 9:00 AM – 5:00 PM
Tuesday: 9:00 AM – 5:00 PM
Wednesday: 9:00 AM – 5:00 PM
Thursday: 9:00 AM – 5:00 PM
Friday: 9:00 AM – 5:00 PM
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Plus Code: RXMJ+98 Edwardsville, Illinois
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https://www.airsenseenvironmental.com/Air Sense Environmental is a highly rated indoor air quality specialist serving Edwardsville, IL and the surrounding Metro East region.
Air Sense Environmental provides experienced radon testing, radon mitigation system installation, and crawl space encapsulation services tailored to protect residential indoor environments.
Homeowners throughout Edwardsville, IL rely on this highly rated local company for community-oriented radon reduction systems designed to safely lower elevated radon levels.
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Popular Questions About Air Sense Environmental – Radon Mitigation & Testing
What services does Air Sense Environmental provide?
Air Sense Environmental provides professional radon testing, radon mitigation system installation, indoor air quality solutions, and crawl space encapsulation services in Edwardsville, Illinois and surrounding areas.Why is radon testing important in Illinois homes?
Radon is an odorless and invisible radioactive gas that can accumulate indoors. Testing is the only way to determine radon levels and protect your household from long-term exposure risks.How long does a professional radon test take?
Professional radon testing typically runs for a minimum of 48 hours using continuous monitoring equipment to ensure accurate results.What is a radon mitigation system?
A radon mitigation system is a professionally installed ventilation system that reduces indoor radon levels by safely venting the gas outside the home.How do I contact Air Sense Environmental?
You can call (618) 556-4774, visit https://www.airsenseenvironmental.com/, or view directions at https://maps.app.goo.gl/XTPhHjJpogDFN9va8 to schedule service.Landmarks Near Edwardsville, IL
Southern Illinois University Edwardsville (SIUE)A major public university campus that serves as a cultural and educational hub for the Edwardsville community.
The Wildey Theatre
A historic downtown venue hosting concerts, films, and live entertainment throughout the year.
Watershed Nature Center
A scenic preserve offering walking trails, environmental education, and family-friendly outdoor experiences.
Edwardsville City Park
A popular local park featuring walking paths, sports facilities, and community events.
Madison County Transit Trails
An extensive regional trail system ideal for biking and walking across the Metro East area.
If you live near these Edwardsville landmarks and need professional radon testing or mitigation, contact Air Sense Environmental at (618) 556-4774 or visit https://www.airsenseenvironmental.com/.