Tamil Nadu issues order to move towards energy efficient buildings

CHENNAI: According to the government order dated April 19, all buildings that will be connected to load of 100 kW or contract demand of 120 kVA and higher or built-up area of 2,000 sqm or more must meet energy efficient and climate resilience requirements.

The order mandates maximum wall thermal transmittance value (U Value), solar heat gain coefficient, visible light transmittance value and residential envelope transmittance value to reduce heat inside buildings and usage of electricity for cooling. The order has been issued based on recommendations by member-secretay of Chennai Metropolitan Development Authority.

However, the government has instructed Tamil Nadu Housing Board and Tamil Nadu Urban Habitat Development Board to follow the guidelines in the first instance as the guidelines are aimed at achieving energy efficiency and climate resilience in constructions.

"Tamil Nadu Housing Board and Tamil Nadu Urban Habitat Development Board are instructed to engage suitable experts with adequate domain knowledge on outsourcing basis to ensure the compliance of the recommendations in their respective construction projects," the order stated.

The government will also make an amendment in Tamil Nadu Combined Development and Building Rules, 2019 to incorporate the recommendations for other buildings.

U-value, is the rate of transfer of heat through a structure, divided by the difference in temperature across that structure. The better-insulated a structure is, the lower the U-value will be. Solar heat gain coefficient (SHGC) is the fraction of solar radiation admitted through a window, door, or skylight - either transmitted directly or absorbed, and subsequently released as heat inside a home.

Visible Light Transmission (VLT) is a measurement of the amount of visible light waves that transmit through a material. Residential envelope transmittance value is the net heat gain rate (over the cooling period) through the building envelope of dwelling units (excluding roof) divided by the area of the building envelope (excluding roof) of dwelling units.