Measured Cooling Energy and Peak Demand Savings from the Installation of Cool Roofs on Two High-tech Educational Buildings in Hyderabad, India.

In this study, sponsored by the U.S. AID, the Heat Island Group at the Lawrence Berkeley National Laboratory (LBNL) and Center for IT in Building science International Institute for Information Technology (IIIT) Hyderabad measured and analyzed air-conditioning energy savings and power-demand reduction of two identical office buildings in Hyderabad, India that were retrofitted with a reflective roof coating. The buildings were:

SLC West at BHADHURPALLI, HYD, INDIA
- one story.
- light gray concrete roof

SLC East at BHADHURPALLI, HYD, INDIA

one story.
light gray concrete roof

Link to:

Demonstration Project Photo Gallery

Before instrumenting these buildings, we collected data on building characteristics and performed simulations of energy use and savings. Characteristics we noted included:

Floor area
Number of stories
Roofing material, age, and reflectance
Roof system
Attic ventilation
Heating, cooling, and air-handling systems
Duct systems
Building schedules
Lighting and systems schedules
Thermostat settings

Link to:

SLC East Schematics with

Monitoring Locations

SLC West Schematics with

Monitoring Locations

The equipment measured:

Weather: outdoor ambient air temperature and relative humidity, and solar flux (measured by a weather tower at fifteen-minute intervals).
Energy: whole-building electricity use, cooling-electricity use, and heat flux through the roof. The cooling energy use was measured using current transducers. All data flow into a data logger (one in each building) that was remotely connected to our computers at IIIT-Hyderabad. We observed and collected data at least once a day.
Building Temperatures: temperatures of the roof's surface and underside, the ceiling plenum air temperature, and the indoor and return air temperatures.

Link to: Demonstration Project Data

We also provided information to the community by placing a temporary display kiosk in the lobby or waiting room of the building. This kiosk provided information about the energy-saving potential of white roofs, as well as real-time data about the roof temperature, the building cooling energy use, and the cooling energy saved by using a white roof.

After monitoring the buildings throughout the heating season of 1996, the roofs of the buildings were painted with reflective coatings that increased the roof reflectivities from 0.20 to 0.60. The infrared image of the roof showed an immediate reduction in roof temperature of about 40°C (70°F) after the application of the coating.

Link to: Demonstration Project Results

A white coating reduced the roof temperature by about 40°C (70°F). (source heat Island group).