Supply Ventilation in an Apartment: Options, Pros, and Cons (Los Angeles)

In Los Angeles, apartment air can feel stale due to tight windows, traffic pollution, wildfire smoke, and frequent use of AC. Supply ventilation (fresh-air intake) helps bring controlled outdoor air indoors, improving oxygen levels and reducing CO2, odors, and excess humidity. Below are common apartment-friendly options, with their key benefits and drawbacks. 1) Passive air inlets (wall valves or window trickle vents). These are simple openings with a basic filter and adjustable flap. Pros: low price, no power, minimal maintenance. Cons: airflow depends on wind and pressure, weak filtration, possible drafts and noise, and limited control during smoke events. 2) Compact “breather” units (through-wall supply fans). A small powered device pulls air from outside and passes it through multi-stage filtration (often up to HEPA). Pros: stable airflow, better filtration for dust and some smoke, measurable improvement in CO2, easy installation in many apartments. Cons: fan noise at higher speeds, needs filter replacements, requires a wall penetration and electrical access. 3) HRV/ERV systems (heat/energy recovery ventilators). These exchange air while reducing cooling losses—useful in LA’s warm seasons. Pros: balanced ventilation, better comfort, lower energy penalty than exhaust-only methods. Cons: higher cost, more complex installation, space for ducts or larger units, and professional design is usually needed. 4) Ducted mini supply system (fan + filter box + diffusers). Pros: can serve multiple rooms, strong filtration (e.g., MERV 13), good control. Cons: hardest to install in apartments, requires planning to avoid noise and vibration. When choosing, prioritize filtration (MERV 13+ or HEPA if smoke is a concern), noise rating, and where the air will be delivered (bedroom/living area). Also ensure exhaust paths exist (bathroom/kitchen) so fresh air can circulate rather than pressurize one room. Properly selected supply ventilation is one of the most effective ways to upgrade indoor air quality in an LA apartment.