What is it about?

If you live in a smoggy or highly polluted city, “fresh air” isn’t always fresh. So what keeps your home safer: opening the windows or turning on an air purifier? A new study of urban households says the real answer is a bit of both. We paired interviews with 101 families and a computer model of a typical flat. We tested two common routines: (1) open the windows only when outdoor air is clean (“pollution-aware” ventilation), and (2) use a bedroom purifier while opening windows based on comfort. What happened? When windows opened only on cleaner hours, homes used about 5–8% more cooling energy—because they stayed shut during many polluted periods and relied more on AC. But when a good purifier ran in the bedroom, indoor particle levels dropped by roughly 47% compared with outdoors—at the cost of ~11% more electricity. Money matters, too. On average, people said they’d spend around ₹200 per month either on private purifiers or on public programs like cleaner buses and better transit—showing that households value both personal and city-level solutions. The smart takeaway isn’t “purifier vs. windows,” but when to use which. We propose a simple rule of thumb from their data: when outdoor pollution gets high, a purifier alone can’t keep up—so close the windows and let it work; when the air outside improves, open up for natural ventilation. Basic sensors or phone-based air-quality alerts can automate those switches, protecting lungs without wasting power. In other words, clean indoor air is a choreography: open when it’s clean, filter when it’s not.

Featured Image

Why is it important?

It matters because in cities like Delhi, dirty outdoor air regularly seeps indoors and harms health—contributing to asthma, heart disease, and millions of premature deaths—so households face a daily choice between opening windows for comfort or filtering the air, with real costs either way. Our study shows those choices aren’t trivial: “pollution-aware” window use raises cooling energy by about 5–8%, while a good purifier cuts indoor particles roughly in half but adds ~11% to electricity—quantifying the trade-off families actually face. Crucially, it offers a practical way forward—manage windows and purifiers together based on outdoor pollution (close windows or ramp the purifier when outside air crosses a data-derived threshold)—which can protect health without wasting energy and guides sensible incentives and building codes.

Perspectives

Writing this paper felt meaningful because it connects everyday human decisions—when to open a window, when to switch on a purifier—to the hard numbers of energy and health. I loved the mix of fieldwork and modeling: listening to people on a daily basis describe their routines and worries, then testing those realities in simulation to see what actually helps. Collaborating with colleagues who care about both equity and engineering sharpened the work and made it more honest. My hope is simple: that this study nudges the conversation away from “gadgets vs. behavior” and toward small, doable routines—close the window when the air turns dirty, let the purifier work, open up when it’s clean—that households can own without constant vigilance. If it also encourages policymakers to back practical, verifiable indoor-air gains (not just device counts), then we’ll have turned research into something that saves lungs and lowers bills

Ritwik Agarwal
International Institute of Information Technology Hyderabad

Read the Original

This page is a summary of: Energy and Indoor Air Quality Tradeoffs of Personal Air Cleaners and Natural Ventilation in Urban Households, November 2025, ACM (Association for Computing Machinery),
DOI: 10.1145/3736425.3772359.
You can read the full text:

Read

Contributors

The following have contributed to this page