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Designing for IAQ: Why Balanced Ventilation Is a Must-Have in Tight Homes
Reading time: 5 minutes
Comfort
Today’s residential construction is tighter, better insulated, and more energy efficient than ever before. But while these advancements reduce energy loss, they also limit natural air exchange leading to trapped moisture, volatile organic compounds (VOCs), and lingering indoor pollutants.
Balanced ventilation is no longer optional. Builders and HVAC contractors are increasingly turning to HRVs (heat recovery ventilators) and ERVs (energy recovery ventilators) to meet building code requirements and deliver cleaner, healthier indoor air.
The Ventilation Challenge in Modern Homes
Homes built to meet the 2021 and 2024 IECC energy codes are effectively sealed envelopes. Without mechanical ventilation, stale indoor air stays trapped, leading to:
Moisture buildup, which can contribute to mold and structural issues
VOC accumulation from finishes, furniture, and cleaning agents
Elevated CO₂ levels, especially in bedrooms and other enclosed areas
HVAC systems that recirculate rather than refresh the air
ASHRAE Standard 62.2 sets minimum ventilation requirements for acceptable indoor air quality in residential buildings. Mechanical systems like HRVs and ERVs are the most reliable way to meet these requirements.
ASHRAE 62.2-2022 emphasizes that natural infiltration alone is not sufficient in modern, tightly built homes. Mechanical whole-house ventilation—through continuous supply, exhaust, or balanced systems—is required to maintain healthy indoor air quality.
Meeting Code with Mechanical Ventilation
As building envelopes tighten, codes have evolved. The 2021 and 2024 International Residential Code (IRC) and IECC versions require mechanical ventilation systems in most new homes. Local jurisdictions may also adopt even more stringent standards, such as:
California Title 24:
Requires whole-house ventilation meeting ASHRAE 62.2
Canada's National Building Code:
Mandates balanced ventilation for new homes
ENERGY STAR® Certified Homes:
Require continuous or demand-controlled mechanical ventilation
Balanced systems like HRVs and ERVs not only comply with these codes but offer homeowners energy-efficient comfort with improved air quality. Contractors who plan for ventilation early in the design phase save time, avoid costly retrofits, and ensure inspection readiness.
HRV or ERV? Climate and Application Matter
HRVs and ERVs both exchange stale indoor air with fresh outdoor air, capturing energy in the process. Choosing the right system depends on climate zone and occupancy patterns.
| System | Best For | How It Works |
|---|---|---|
| HRV | Cold, dry climates | Transfers heat from outgoing to incoming air |
| ERV | Humid or mixed climates | Transfers heat and moisture |
Pro Tip: In hot, humid regions, ERVs reduce latent load by transferring incoming humidity back outside. In cold climates, HRVs reduce heat loss without adding indoor moisture.
Additional considerations:
ERVs can reduce over-drying in winter in colder regions
HRVs offer simpler installation in dry, cold climates with fewer humidity concerns
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When Ventilation Is Overlooked
In today’s airtight homes, relying on a single exhaust fan or natural infiltration for ventilation simply isn’t enough. Homes without balanced ventilation often experience persistent condensation on windows, lingering odors, and generally stale air. These symptoms are frequently reported within the first heating or cooling season.
The core issue is pressure imbalance and lack of fresh air exchange. Without a system to introduce filtered outdoor air while exhausting stale air, pollutants and moisture accumulate.
By installing a balanced HRV or ERV system, contractors can resolve these issues effectively. A properly sized unit with MERV filtration and continuous airflow helps reduce complaints, improves comfort, and ensures the home operates as intended.
Installing mechanical ventilation during construction also avoids costly retrofits and supports code compliance from the start.
Specifying an HRV/ERV: What to Look For
When selecting or specifying an HRV or ERV, prioritize the following:
Correct airflow capacity per ASHRAE 62.2, IECC, or local code
High-efficiency ECM motors to reduce energy use
MERV 3 to 13 filtration to capture outdoor particulates
Quiet operation to avoid homeowner complaints
Flexible port configurations for tighter mechanical rooms
Easy access to filters and core for maintenance
Smart controller compatibility for demand ventilation
Units such as the HERO Series from leading manufacturers are designed for fast installation and simplified commissioning with onboard diagnostics and real-time airflow displays.
For Contractors
Installation Tips for Long-Term Performance
Even the most advanced ERV or HRV will underperform if poorly installed. Follow these best practices:
Avoid short-circuiting airflow by placing supply and exhaust vents far apart
Keep duct runs short and straight, minimizing resistance
Seal all joints to prevent air leakage and ensure static pressure
Use balancing dampers to fine-tune airflow per manufacturer recommendations
Verify system operation after install (don’t rely on default settings)
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Tools & Resources
To simplify specification and installation, look for manufacturers that offer:
BIM/Revit files for your projects
Ventilation sizing calculators
CSI Master Format specs
Installation videos and checklists
Regional sales and technical support
These tools can shorten design time, reduce errors, and keep projects moving smoothly through inspections. ProTip: On Fantech.net; the product pages contain those assets.
Common Misconceptions: For Contractors
Let’s address a few myths your clients might believe or that might be holding your team back:
"Opening a window is enough."
Unfiltered and uncontrolled airflow can bring in pollen, smoke, or humidity.
"Ventilation wastes energy."
HRVs and ERVs recover 60–80% of heat and some moisture, saving energy over time.
"They’re too hard to maintain."
Modern systems offer simple filter access and visual maintenance reminders.
"Only large homes need ventilation."
Even small, airtight units trap pollutants fast.
Educating your customers on these misconceptions builds trust and positions you as a ventilation expert.
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Build Better with Balanced Ventilation
Fresh air isn’t a luxury—it’s a system-level requirement for homes built in 2025 and beyond. Whether designing to code-minimum or high-performance standards, HRVs and ERVs offer lasting advantages:
Healthier indoor air
Lower moisture risks
Energy savings through heat recovery
Fewer callbacks and complaints
Looking for the right solution? Find specs, tools, and selection resources for builders and HVAC pros and explore our solutions.
Sources & References
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