From pollution barriers to health buffers: Rethinking building airtightness under climate variability

Area of Science:

• Environmental science
• Public health
• Building science

Background:

• Climate change alters indoor-outdoor air pollution dynamics.
• Building standards often neglect these shifts, particularly in urbanizing areas with high PM2.5.
• Building airtightness is a key but underutilized strategy for reducing indoor pollution exposure.

Purpose of the Study:

• To analyze the impact of building airtightness on indoor PM2.5 levels and COPD mortality in Chinese cities.
• To identify climate-specific factors influencing airtightness effectiveness.
• To inform building standards and retrofitting strategies for healthier urban environments.

Main Methods:

• Analysis of building airtightness, indoor PM2.5, and COPD mortality data across 36 Chinese cities in five climate zones.
• Modeling of infiltration gains and losses considering climate variables like pressure gradients.
• Calculation of reductions in indoor PM2.5 and COPD deaths at best practice airtightness levels.

Main Results:

• Improved building airtightness significantly lowers indoor PM2.5 concentrations and reduces COPD-related mortality.
• An airtightness effectiveness transition zone was identified, influenced by monsoon boundaries.
• Best practice airtightness led to a 10.6% decrease in indoor PM2.5 and a 6.2% reduction in COPD deaths, with greatest benefits in cold climates.

Conclusions:

• Climate-specific building airtightness targets, combined with ventilation and filtration, are crucial for mitigating indoor pollution.
• Retrofitting leaky and vulnerable housing should be prioritized.
• Joint energy-health metrics can guide funding towards healthier, energy-efficient buildings in urbanizing regions.