Passive House Standards Offer Critical Protection from Wildfire Smoke in NYC
As smoke from wildfires in Canada enveloped New York City, air quality warnings urged residents to remain indoors, although the effectiveness of this advice varies depending on building types. Many residences in NYC, including more than 200,000 pre-war townhouses constructed between 1870 and 1930, allow air leakage five to ten times above Passive House standards. On July 15 and 16, measurements inside a Passive House in Brooklyn indicated PM2.5 levels below 35 micrograms (AQI 100), while outdoor levels surpassed 150 micrograms (AQI 200). During peak times, indoor air quality was 90 percent cleaner than that of a typical townhouse, decreasing to 75–80 percent over time. Themis Haralabides reported that homeowners with Passive House upgrades noticed no change in air quality amid the 2023 wildfires.
Key facts
- Wildfire smoke from Canada triggered air quality alerts in NYC in July 2026.
- Most NYC townhouses and rowhouses were built between 1870 and 1930 and lack modern ventilation.
- Passive House standards require ≤0.6 air changes per hour at 50 Pascals.
- Typical unsealed NYC brownstones have 5–10 air changes per hour.
- Indoor PM2.5 in a Brooklyn Passive House stayed below 35 µg/m³ during the event.
- Outdoor PM2.5 peaked above 150 µg/m³ (AQI ~200).
- Passive House indoor air was 90% cleaner during peak spikes and 75–80% cleaner over sustained periods.
- The 2023 Canadian wildfire season burned over 45 million acres.
Entities
Institutions
- reBuild Workshop
- Environmental Protection Agency (EPA)
Locations
- New York City
- Brooklyn
- Canada
- American West
- Europe
- Harlem
- Upper West Side