Building-science calculators

Three numbers a space should earn.

Passive cooling, harvested water, and energy saved — estimated from your inputs against published Indian references. Planning figures to think with, not certified results. Each calculator shows the sources it uses.

Base cooling load
kW
After passive design
kW
Energy saved / yr
Annual cost saving

Sources. Climate-zone base temperatures, solar gain (W/m²) and cooling-degree-days follow CBRI climate classification; orientation factors from sun-path analysis; shading effectiveness from standard heat-gain reduction ranges. Tariff assumed ₹8/kWh, 8 cooling hours/day.

Annual harvest
L
Monthly average
L
Annual water saving
Tank size (15-day)
L

Sources. Annual rainfall from IMD city normals; runoff coefficients by roof material; demand from CPHEEO norm (135 L/person/day domestic). Harvest = area × rainfall × runoff coefficient. Water cost assumed ₹15/kL; tank sized for 15 days of average monthly harvest.

Baseline EPI
Improved EPI
Energy saved / yr
CO₂ avoided / yr
t

Sources. EPI benchmarks (kWh/m²/yr) by building type follow ECBC conventional baselines; per-measure savings are standard efficiency ranges, capped at 60% combined. Grid emission factor 0.82 kgCO₂/kWh (CEA). Tariff ₹8/kWh; payback uses ₹500/m² indicative implementation cost.

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