Why Standardizing AC Temperature (20°C–28°C) Makes Sense – And How Architecture Must Evolve

This is not just a regulatory change; it’s a bold step toward environmental sustainability, energy efficiency, and a more climate-resilient future.

🌡️ Why Standardize Between 20°C to 28°C?

India faces a growing demand for electricity, particularly during summer months when AC usage spikes. By setting a uniform AC temperature of 28°C, we can reduce:

• Lower energy consumption
• Reduce electricity bills
• Cut carbon emissions
• Avoid overloading the power grid

While the comfortable range for ACs lies between 20°C and 28°C, 28°C is being promoted as the default or optimal setting — particularly in public buildings — due to its enormous energy-saving potential. The key is making that temperature feel cool enough, which brings us to architecture.

🏗️ Architectural Adjustments: Key to Making 28°C Comfortable

Setting ACs at 28°C can be truly effective only if buildings are designed to naturally stay cooler. This requires smart architectural design, especially in how the building envelope is constructed and the materials used.

Here’s how to make buildings more thermally efficient—and examples of where it’s already working:

🧱 1. Improving the Building Envelope

A building’s “envelope” — the walls, roof, windows, and floor — acts as the first defense against external heat. Strengthening it can drastically cut indoor temperature rise.

✅ Insulation

XPS or PU foam insulation is used for roofs and walls.

✅ Cool Roofs

Reflects sunlight and reduces the heat absorbed by the roof.

Cool roof coatings in low-income housing, cutting indoor temperatures by 4–5°C.

✅ Double-Glazed Windows

Two panes of glass with an air gap reduce heat gain and noise.

✅ Shading Devices

Blocks direct sunlight from hitting windows and walls.

Horizontal and vertical louvers and pergolas that reduce solar gain on glass façades.

🧪 2. Material Innovations (with Examples)

Choosing the right materials is just as important as design. The following innovations help in naturally reducing indoor heat:

✅ High Albedo Materials

What it does: Reflect more solar radiation than they absorb.

Example:

White terrazzo tiles used on the rooftops of residential buildings in Chennai have shown to reduce interior temperature by 3–4°C.

✅ Phase Change Materials (PCMs)

What it does: Absorbs heat during peak hours and releases it when temperatures fall—regulating room temperature.

Example:

PlusIQ™ PCM panels by BASF, installed in office buildings in New Delhi, help maintain a stable indoor climate without excessive AC use.

✅ Ventilated Façades

What it does: Allows trapped heat between outer and inner wall layers to escape via ventilation, reducing internal temperature.

Example:

Godrej BKC building in Mumbai uses ventilated stone cladding, improving indoor thermal comfort by 2–3°C.

🌳 3. Greeneries and Trees: Nature’s Cooling System

Vegetation is one of the most effective, low-cost solutions to improve thermal comfort—indoors and outdoors. Trees, shrubs, vertical gardens, and green roofs naturally cool their surroundings by providing shade and releasing moisture through evapotranspiration.

✅ Tree Canopy Cover

What it does: Reduces surface and ambient temperatures in surrounding areas.
Example: Urban streets in Bengaluru lined with trees record up to 5°C cooler surface temperatures than exposed roads.

✅ Green Roofs and Walls

What they do: Act as thermal barriers, lowering roof temperatures and reducing heat transfer into buildings.
Example: The CSE building in New Delhi features a rooftop garden that helps maintain comfortable indoor temperatures without intensive AC use.

✅ Landscaped Courtyards and Permeable Surfaces

What they do: Enable heat dissipation and reduce the urban heat island effect.
Example: IIM Ahmedabad’s campus layout includes internal green courtyards that regulate microclimate naturally.

✅ Long-Term Benefits

1. Energy Efficiency: Operating ACs between 20°C to 28°C reduces compressor load, leading to lower power usage.
2. Environmental Impact: Reduced energy demand means less fossil fuel consumption and fewer greenhouse gas emissions.
3. Cost Savings: Households, commercial spaces, and government buildings will all benefit from reduced electricity costs.
4. Healthier Adaptation: Prevents temperature shocks from overly cold environments.
5. Climate Resilience: Greener cities and smarter buildings are better equipped for rising global temperatures.

🌿 Passive Design Strategies

Besides materials and insulation, adopting passive cooling techniques will be essential:

• Cross Ventilation: Allowing natural air movement through aligned openings.
• Thermal Mass: Using materials like concrete and brick that absorb and slowly release heat.
• Landscaping: Planting trees and green roofs to provide natural shade and cooling.

🎯 In Simple Terms:

To make the 20°C–28°C range work — and make 28°C feel pleasant — we need buildings that are:

• Better sealed from outside heat
• Built with materials that resist heating
• Designed to allow natural cooling

That’s what smart architectural design is all about: building in a way that the structure works with the climate, not against it.

💡 Final Thoughts

Standardizing AC temperature settings between 20°C and 28°C is a forward-looking policy. By capping energy-hungry cooling at 20°C and promoting 28°C as the new normal, we protect our environment while ensuring comfort.

But comfort at 28°C is only possible when architecture and materials do their part. The synergy of smart policy, passive design, and energy-efficient technologies can help create a cooler, more sustainable India — one well-designed building at a time.