Bureau of energy efficiency introduced Energy conservation building code (ECBC) in May 2007.

This code has become mandatory in many states of India. Ten states have notified ECBC: Rajasthan, Odisha, Uttarakhand, UT of Puducherry, Andhra Pradesh, Punjab, Telangana, Haryana, West Bengal, and Karnataka Also the green building rating system like GRIHA requires compliance with ECBC code for their certification.

In this article we will discuss about whole building design approach related to HVAC system to meet ECBC requirements.

Whole Building Design Approach

In whole building design approach six conservative measures are adopted

• Reduce cooling loads by controlling unwanted heat gains
• Expand the comfort envelope (reduced latent heat load, air movement – ceiling fans, less insulated furniture, more casual dress codes)
• Optimize the delivery systems (reducing velocity, pressure and friction in ducts and piping)
• Apply non-refrigerative cooling techniques
• Serve the remaining load with high-efficiency refrigerative cooling
• Improve controls (sensors, signal delivery, user interface, simulators, etc.)

1.   Reduce cooling loads by controlling unwanted heat gains

Cooling load reduction measures are shown in the picture below

2. Expand the comfort envelope

(reduced latent heat load, air movement – ceiling fans, less insulated furniture, more casual dress codes)

Sensitivity of ASHRAE comfort conditions to clothing

                                                                                                      The open mesh fabric in this chair keeps skin temperatures cooler than typical foam and fabric covered chairs

3. Optimize the delivery systems

(reducing velocity, pressure and friction in ducts and piping)

Diffuser operation and terminology

A properly operating diffuser spreads the supply air out along the ceiling nearly as far as the wall (or halfway to neighboring diffusers) before the air begins to drop into the space. At reduced flows, diffusers may “dump” their air in a narrow column, which creates poor air distribution and may chill occupants directly below the diffuser.

Round and rectangular ducts

Round ducts are more efficient, lighter, and quieter than rectangular ducts, which require at least 27 percent more metal per unit of air-handling capacity.

4.  Apply non-refrigerative cooling techniques

»     Ground-coupled cooling

»     Night-sky radiation cooling

»     Cooling with outdoor air

»     Evaporative cooling

»     Dessicant dehumidification and cooling

»     Heat pipe cooling cycle enhancements

»     Hydronic cooling

5. Serve the remaining load with high-efficiency refrigerative cooling

Components and features of efficient design are shown below

6. Improve controls

(Sensors, signal delivery, user interface, simulators, etc.)