01/14/2026
A blower door test uses a large, calibrated fan in an exterior door to depressurize a house, measuring how much outside air leaks in through cracks and gaps to quantify its airtightness, helping to find drafts, improve energy efficiency, reduce utility bills, and ensure proper ventilation for indoor air quality. You do it to identify hidden air leaks, document energy performance, meet building code, and make targeted air-sealing improvements, saving money and increasing comfort.
A house can be too tight if it lacks proper mechanical ventilation, leading to poor indoor air quality, moisture buildup (mold/mildew), and potential safety issues like combustion appliance backdrafting, but the building itself shouldn't be sealed; instead, it should be built tight and ventilated right with controlled systems like Energy Recovery Ventilators(ERVs). The solution isn't leaky walls, but adding systems (like HRVs/ERVs) that provide fresh, preconditioned, filtered air while exhausting stale air, ensuring healthy air without sacrificing energy efficiency.