When summer temperatures soar, many buildings turn into ovens. But while discomfort is obvious, the hidden costs of overheating, on energy bills, health, and productivity that often go unnoticed.
How much difference does passive design make? We tested it. Two identical apartments were simulated during summer: same floorplan, same city block. But only one used passive strategies. Same Floorplan, Different Strategy:
| FEATURE | UNIT A- Passive Design | UNIT B-Conventional Build |
| ORIENTATION | East-West | East-West |
| WINDOWS | North-East-SouthDouble Glazed, cross ventilated | North-East-South,Single pane, no airflow path |
| SHADING | Overhangs designed for each orientation and galzing ratio | Standard overhangs for south & west orientation |
| INSULATION | High performance envelope with low U values. | Conventional building materials used |
Results: Over three months (June–August), the difference in performance and experience was stark.
| Metric | Unit A (Passive) | Unit B (Non-Passive) |
| Avg. Indoor Temp | 25.2°C | 30.1°C |
| Cooling Energy Use | 75 kWh | 300 kWh |
| Cooling Cost | ₹2500/month | ₹11000/month |
| Comfort Rating (1–10) | 9.1 | 5.3 |
| Heat-related Sick Days | 0 | 3 reported |
| Work-from-Home Productivity | +18% (baseline) | –11% (baseline) |
- Unit A: Stayed cool with minimal AC, ₹8,300/month in savings, better comfort
- Unit B: Overheated, required constant AC, ₹30,000 in bills
Passive Design Payback:
The passive features in Unit A (shading devices, improved glazing, insulation) had an estimated upfront cost of ₹2,49,000. With cooling savings of nearly ₹8,300/month during peak season, the payback period is just over 2.5 years. Add in the non-monetary benefits-health, comfort, and productivity and the return on investment is even stronger.
Bottom Line
Overheating is more than a nuisance, it’s a liability. If you’re designing or retrofitting buildings, consider this your call to action. Passive design isn’t a luxury. It’s a necessity for tenant wellbeing, energy resilience, and long-term cost savings.
Design smarter. Save money. Stay comfortable.
