In our previous discussion, we have already discussed about cool roofs, its importance in sustainability and rating systems for accreditation of the same. Now, we shall probe further into IGBC Rating System for both commercial and residential complexes.

The Indian Green Building Council (IGBC), part of the Confederation of Indian Industry (CII), develops rating systems to promote sustainable, green buildings in India.These systems focus on national priorities like benchmarks for energy efficiency, water conservation, waste management, reduced environmental impact,and improved occupant health.All these parameters are graded against benchmarks formulated through it’s rating system.

IGBC offers separate rating systems tailored to different building types,keeping in mind the functional utility and differential contexts within which such ratings would vary.Commercial buildings like office spaces,malls,hotels,Information Technology parks,Logistics parks etc typically fall under the IGBC Green New Buildings Rating System,while residential buildings like homes, apartments,common  societies use systems like IGBC Green Homes or IGBC Green Residential Societies. As mentioned earlier,the bifurcation has been done keeping in mind the unique set of challenges required to be encountered with.

IGBC for Commercial Buildings.

This system applies to new commercial and non-residential buildings (air-conditioned or non-air-conditioned),including offices,IT parks,banks,shopping malls,hotels,airports,convention centers, and similar types of establishments.It addresses measurable green features across key categories.

Main Categories and Focus Areas:

• Sustainable Architecture and Design: Integrated design, passive architecture,site preservation( both on and off site).
• Site Selection and Planning: Proximity to public transport,heat island reduction (roof and non-roof),outdoor light pollution reduction,universal design,preservation of trees/topography.
• Water Conservation: Rainwater harvesting (roof & non-roof),water-efficient fixtures,landscape design,wastewater treatment and reuse,metering.
• Energy Efficiency: Minimum energy performance(aligned with standards like ECBC), ozone depleting substances elimination,enhanced efficiency,on site/off site renewables,eco-friendly refrigerants,commissioning,metering.
• Building Materials and Resources: Sustainable/recycled/certified materials,waste segregation (post-occupancy),organic waste management,construction waste handling.
• Indoor Environmental Quality: Fresh air ventilation,tobacco smoke control,CO₂ monitoring, daylighting,outdoor views,low-emitting materials,occupant well-being.
• Innovation and Development: Innovative practices,accredited professionals.

Certification Levels (based on points out of 100):

• Certified
• Silver 
• Gold
• Platinum (specific point thresholds vary by version).

Mandatory requirements must be met,with credits earning additional points.

IGBC for Residential Buildings

Residential projects use specialized systems:

• IGBC Green Homes :  For new individual homes or multi-dwelling units (apartments). Focuses on single-family or grouped residential construction.
• IGBC Green Residential Societies :  For existing or new multi-dwelling residential societies/complexes(apartment communities).

Key Categories 

• Site Selection & Planning (natural topography preservation, heat island reduction, amenities for differently-abled).
• Water Efficiency (rainwater harvesting, efficient fixtures, wastewater reuse, metering).
• Energy Efficiency (CFC-free equipment, enhanced performance, renewables like solar, efficient appliances).
• Materials & Resources (waste segregation, recycled/local/rapidly renewable materials).
• Indoor Environmental Quality (daylighting, fresh air, low-VOC materials, cross-ventilation).
• Innovation & Design.

Additional Residential Focus:

• Features like solar water heating, organic waste management, green home guidelines, and post-occupancy practices.
• For societies: Facility management, no-smoking policies, green housekeeping, energy metering in common areas.

Certification Levels (points-based, varying by individual unit vs. multi-dwelling):

• Certified, Silver, Gold, Platinum (higher thresholds for multi-dwelling projects).

Role of cool roofs in IGBC ratings for both residential and commercial spaces 

Cool Roofs are a key sustainable feature in IGBC guidelines,particularly under Site Selection and Planning for reducing the Urban Heat Island (UHI) effect .They involve high-reflectance, high-emissivity materials that reflect the incoming solar radiations and emit absorbed heat,keeping roof surfaces cooler.

Importance and Benefits of Cool Roofs

In India's tropical and hot climates cool roofs are especially valuable due to intense solar radiation, high temperatures,and rising cooling demands from climate change and rapid pace of urbanization.

• Energy Efficiency: Reduce indoor temperatures by 3–5°C,lowering air-conditioning loads by 10–26% (or up to 25-30% annually in tropical/subtropical zones).This aligns with IGBC's energy credits.
• Thermal Comfort: Improve occupant well-being in both air-conditioned commercial spaces and non-conditioned residential homes/societies, reducing heat stress,extremely critical in heatwaves.
• Urban Heat Island Mitigation: Lower local ambient temperatures by 2°-4C (or more at scale), benefiting entire neighborhoods and cities.
• Environmental Impact: Cut greenhouse gas emissions (10–12 kg CO₂/m² roof area annually from energy savings), improve air quality by reducing smog formation, and contribute to global cooling via radiative forcing.Moreover, these paints are low on Volatile organic compounds ( VOCs).
• Cost Savings: Low upfront costs,quick payback through electricity bill reductions,extended shelf life of roofs (less thermal stress), and potential incentives in green building certifications.
• Broader Resilience: Help offset rising cooling energy demand from climate change ( in cities like Ahmedabad, scaling cool roofs can reduce projected increases in AC use).

IGBC Guidelines for Cool Roofs

Cool roofs earn points under Heat Island Reduction, Roof (SSP Credit 7 in Green New Buildings; similar in Green Homes/Societies).

For Commercial (IGBC Green New Buildings Rating System):

• Low-sloped roofs (<2:12): Minimum SRI 78.
• Steep-sloped roofs (>2:12): SRI 29–64.
• Points: 1 for >75% roof area coverage; 2 for >95%.
• Often combined with non-roof measures (e.g., shaded parking) for full credit.
• Mandatory in some contexts via ECBC linkage; optional but highly recommended for higher certification levels.

For Residential (IGBC Green Homes / Green Residential Societies):

• Similar SRI thresholds.
• Cover ≥50% exposed roof area with high-reflective materials/vegetation for 2 points; ≥75% for 4 points (in older versions; check latest).
• Includes podiums/utility blocks; excludes solar PV areas, skylights.
• Encourages green roofs (vegetation) for added benefits like stormwater management.

These contribute to overall points toward Certified, Silver, Gold, or Platinum levels, often synergizing with passive design, energy efficiency, and innovation credits.

Case Studies Highlighting Cool Roofs’ efficacy 

• Hyderabad Office Buildings :  Cool roof applications on concrete roofs reduced AC electricity by 10–19%, with peak temperature drops and measurable energy savings,directly supporting IGBC style credits.
• Ahmedabad Cool Roofs Initiative (2017 onward): Pilots in low-income areas under District Cooling Action Plan( DCAP) showed 2–5°C indoor cooling, heat stress reduction, and city-scale UHI mitigation; integrated into Heat Action Plans and influenced state policies.
• Telangana State-Wide Cool Roof Policy (2023–2028): Mandates for government/commercial buildings (and larger residential plots); targets 300 sq.km coverage, projecting 600 million kWh annual savings,many projects align with IGBC for certification.

Cool roofs are a simple,low cost,highly affordable ,high-impact passive strategy for IGBC projects in hot regions to integrate during new builds or retrofits for better certification scores,and climate resilience.