What are the Mandatory Requirements for ECBC Compliance with Reference to HVAC System of Building
Following are the Mandatory Requirements for ECBC Compliance with Reference to HVAC System of Building.
- Natural ventilation
- Equipment Efficiency
- Piping and Ductwork
- System Balancing
» As per National Building Code of India 2005
SOURCE: Bureau of Indian Standards, National Building Code of India 2005, Part 8 Building Services, Section 1 Lighting and Ventilation
Minimum Equipment Efficiencies
» Cooling equipment shall meet or exceed the minimum efficiency requirements in ECBC Equipment not listed shall comply with ASHRAE 90.1-2004 §6.4.1
» Unitary Air Conditioner shall meet IS 1391 (Part 1); Split air conditioner shall meet IS 1391 (Part 2); Packaged air conditioner shall meet IS 8148; Boilers shall meet IS 13980 with above 75% thermal efficiency.
Equipment Efficiencies at IPLV
» Efficiencies at Integrated Part Load Performance (IPLV) values can be calculated as follows:
IPLV = 0.01 A + 0.42B + 0.45C + 0.12D
For COP and EER:
Where: A = COP or EER at 100%; B = COP or EER at 75%; C = COP or EER at 50%; D = COP or EER at 25%
Where: A = kW/Ton at 100%; B = kW/Ton at 75%; C = kW/Ton at 50%; D = kW/Ton at 25%
Controls (Timeclock )
» Code specifies the mandatory use of time clocks to allow scheduling for 24-hour building.
» Allow scheduling for 24-hour building
- Can start and stop the system under different schedules for three different day-types per week
» Take power outages into consideration
- Is capable of retaining programming and time setting during loss of power for a period of at least 10 hours
» Allow custom scheduling
- Includes an accessible manual override that allows temporary operation of the system for upto 2 hours
» Ensure adequate dead band between cooling & heating set points to avoid conflicting thermostat control conditions
» For systems that provide simultaneous heating and cooling
- Controls shall be capable of providing a temperature dead band of 3°C (5°F) within which the supply of heating and cooling energy to the zone is shut off or reduced to a minimum.
» For systems that provide separate heating and cooling
- Thermostats shall be interlocked to prevent simultaneous heating and cooling.
Controls (Cooling Towers & Closed Circuit Fluid Coolers)
» To minimize energy consumption by reducing fan speed during lower ambient conditions
All cooling towers and closed circuit fluid coolers shall have either two speed motors, pony motors, or variable speed drives
Piping and Ductwork
» To minimize energy losses, ECBC requires that piping of heating and cooling systems, (including the storage tanks,) must be insulated
- ECBC specifies required R-values of insulation based on the operating temperature of the system
» To maintain thermal integrity of the insulation
- Insulation exposed to weather shall be protected by aluminum sheet metal, painted canvas, or Plastic cover. Cellular foam insulation shall be protected as above, or be painted with water retardant paint.
» Achieve energy efficiency by optimizing air/water distribution rates for all systems
» Balancing should be done prior to occupancy
» ECBC mandates system balancing be included in specifications in the construction documents
» Construction documents shall require
- All HVAC systems be balanced in accordance with generally accepted engineering standards.
- A written balance report including O&M guidelines be provided for HVAC systems serving zones with a total conditioned area exceeding 500 m2 (5,000 ft2).
System Balancing (Air System Balancing)
» Air systems shall be balanced in a manner to minimize throttling losses. Then, for fans greater than 0.75 KW (1.0 HP), fans must then be adjusted to meet design flow conditions.
» Air System Balancing refers to adjustment of airflow rates through air distribution system devices such as fans and diffusers.
» It is achieved through adjusting the position of dampers, splitter vanes, extractors, etc.
» Design options for improving air distribution efficiency include using
- Variable-air-volume systems
- VAV diffusers
- Low-pressure-drop duct design
- Low-face-velocity air handlers
- Fan sizing and variable-frequency-drive motors
- Displacement ventilation systems
System Balancing (Hydronic System Balancing)
» Hydronic systems shall be proportionately balanced in a manner to first minimize throttling losses; then the pump impeller shall be trimmed or pump speed shall be adjusted to meet design flow conditions.
» Hydronic System Balancing refers to the adjustment of water flow rates through distribution system devices such as pumps and coils, by manually adjusting the position of valves, or by using automatic control devices, such as flow control valves.
» A balanced hydronic system is one that delivers even flow to all of the devices on that piping system.
» When a system is balanced, all of the pressure drops are correct for the devices which translates into reduced energy use & costs for pumping.
ECBC regulates condenser locations to ensure:
- There is no restriction to the air flow around condenser coils
- No short circuiting of discharge air to the intake side
- Heat discharge of other adjacent equipment is not near the air intake of the condenser
» Care shall be exercised in locating the condensers in such a manner that the heat sink is free of interference from heat discharge by devices located in adjoining spaces and also does not interfere with such other systems installed nearby.
ECBC regulates condenser water quality
- to eliminate mineral buildup in condensers and chilled water systems (Mineral deposits create poor heat transfer situations there by reducing the efficiency of the unit)
» All high-rise buildings using centralized cooling water system shall use soft water for the condenser and chilled water system.