Indoor Air Quality Upgrades That Matter for PNW Homes.

TL;DR. The single highest-value IAQ upgrade for most Seattle homes is a MERV 13 media filter cabinet ($500-$900). Catches most smoke-season particulates, handles pollen, lasts 6-12 months per filter. HRV/ERV ($2,800-$5,200) only needed for tight modern homes (post-2010). Whole-home dehumidifier ($2,400-$3,800) for basement humidity issues specifically.

Direct answer, the upgrades that move the needle

For most Seattle homes in order of cost-effectiveness:

The single highest-value upgrade for most Seattle homes is the MERV 13 media filter cabinet upgrade ($500 to $900). Catches most smoke-season particulates, handles pollen, lasts 6 to 12 months per filter, and works with existing HVAC.

Why PNW IAQ matters now

Three things changed in the last 8 years:

MERV 13 vs MERV 16 vs HEPA, what each catches

The catch with MERV 13+: filters restrict airflow. Your HVAC must handle the higher static pressure or it short-cycles and wears out faster. We measure static pressure during consult. Roughly 1 in 4 Seattle homes needs a media filter cabinet (deeper filter housing) before going to MERV 13. Adds $400 to $900.

HRV vs ERV, the ventilation upgrade

For tight modern homes (post-2010 construction or recently weatherized), active ventilation matters more than filtration alone.

HRV (Heat Recovery Ventilator) transfers heat from outgoing stale air to incoming fresh air. Doesn’t transfer humidity. Best for cold-climate, low-humidity environments.

ERV (Energy Recovery Ventilator) transfers heat AND a portion of humidity. Better fit for mixed climates like Seattle (wet winters, drier summers).

Both work by:

1. Continuously pulling stale air from bathrooms and kitchens
2. Drawing in equivalent volume of fresh outdoor air
3. Recovering 70 to 90% of heating/cooling energy in transit

Install runs 1 to 2 days. Cost: $2,800 to $5,200. ROI is comfort and air quality, not energy savings (though the recovery does offset some operating cost).

For homes built before 2000 with leaky envelopes, HRV/ERV is rarely the right starting point. The home is already ventilating itself through air leakage. Tight modern homes (2010+) almost always need active ventilation; the question is whether MERV 13 filtration + occasional window opening is enough or if HRV/ERV is worth the upgrade.

UV light at the coil

UV lights mount inside the return plenum and target microbial growth on the evaporator coil. Real benefits:

• Prevents mold and bacteria buildup on the coil (where it’s wet from condensation)
• Maintains heat transfer efficiency over time (clean coil = better cooling/heating)
• Reduces some allergen viability passing through the system

Real costs:

• UV bulbs cost $80 to $180 and need replacement every 1 to 2 years
• The fixture itself is $400 to $900 installed

UV is most valuable for households with:

• History of mold or mildew issues
• High humidity in the home
• Respiratory sensitivities

Less valuable for: dry-climate homes (much of Eastern Washington), homes with already-clean coils, homes already running MERV 13+ filtration.

When the standalone HEPA approach makes sense

Portable HEPA air purifiers (Coway, Levoit, Winix, Honeywell) range $150 to $600 and handle a single room. Real applications:

• Bedroom-only smoke protection. Run one HEPA purifier in the primary bedroom during smoke events. Costs $250 plus $80/year in filters. Covers the 8 hours of sleep when you most want clean air.
• Allergy household, single highly-affected person. A dedicated purifier in their bedroom or office.
• Renter who can’t modify HVAC. Portable purifiers are the only option when the building HVAC isn’t yours.

For whole-home protection, in-line MERV 13+ filtration in the HVAC system is more effective per dollar than 5+ portable purifiers.

Whole-home dehumidifier

Specific use case: Seattle basements with persistent humidity issues. Symptoms include musty smell, condensation on cold-water pipes, peeling paint near floor edges, visible mold around windows.

Standard HVAC barely touches whole-home humidity in winter because the heating system doesn’t run long enough to dehumidify. A whole-home dehumidifier integrates with existing ductwork and runs independently of heating cycles.

• 70-pint capacity: $2,400 to $3,000 installed (most Seattle homes)
• 95-pint capacity: $2,800 to $3,400 installed (larger homes)
• 125-pint capacity: $3,200 to $3,800 installed (daylight basements with persistent issues)

Not for every home. We assess during consult. Sometimes the right answer is fixing foundation drainage or grading rather than mechanical dehumidification.

Real Seattle IAQ packages by household type