As the Ministry of the Interior expands the mandatory scope of green building labels in building regulations, HVAC system energy-saving design has shifted from a "bonus item" to a "required answer." Within Taiwan's EEWH (Ecology, Energy Saving, Waste Reduction, Health) green building evaluation system, the "Daily Energy Saving" metric is most directly related to HVAC design. As the first article in the "New Era of Building Energy Efficiency" series, this piece analyzes the calculation methods and design strategies for HVAC energy-saving metrics within the EEWH framework.

New Era of Building Energy Efficiency Series
  1. EEWH Green Building Label HVAC Energy Efficiency Metrics (This Article)
  2. 2026 Commercial Energy-Saving Subsidy Complete Guide
  3. ESCO Energy Performance Contracts
  4. 2050 Net-Zero Building Pathway and HVAC Carbon Reduction

1. EEWH and Daily Energy-Saving Metrics

The EEWH green building evaluation system was developed by the Architecture and Building Research Institute of the Ministry of the Interior, and is Taiwan's localized green building certification system[1]. Among its nine evaluation indicators, the "Daily Energy Saving" indicator covers two major areas: building envelope energy saving (ENVLOAD) and HVAC System Energy Efficiency (EAC). The EAC evaluation directly reflects the energy-saving level of HVAC design.

EAC HVAC System Energy Efficiency

EAC is the core metric for quantifying HVAC system energy-saving performance within EEWH. Its calculation considers chiller efficiency, distribution efficiency of air and water delivery systems, energy-saving effects of automatic control strategies, and the application of advanced energy-saving technologies such as heat recovery and ice storage[2]. Lower EAC values indicate better HVAC system energy-saving performance.

2. Impact of Chiller Efficiency

The chiller's COP (Coefficient of Performance) or IPLV (Integrated Part Load Value) is the factor carrying the greatest weight in EAC calculation. Selecting high-efficiency chillers or VRF systems can significantly reduce the EAC value:

  • Centrifugal Chillers: Full-load COP can reach 6.0–7.0, IPLV can reach 8.0–10.0
  • Magnetic Bearing Centrifugal Chillers: IPLV can reach 10.0–12.0, with particularly outstanding performance at partial loads
  • VRF Systems: IPLV approximately 4.0–6.0, with advantages in small to medium buildings

3. Energy-Saving Design for Air and Water Distribution Systems

Distribution system (ductwork, piping, fans, pumps) energy consumption accounts for 20–35% of total HVAC system energy consumption, an area that is easily overlooked but offers significant energy-saving potential[3]:

  • Variable Air Volume (VAV) Systems: Compared to Constant Air Volume (CAV) systems, VAV can reduce airflow at low loads, with fan energy consumption decreasing dramatically according to the cubic law of airflow
  • Variable-Speed Pumps: Chilled water pumps and cooling water pumps with variable-frequency drives, combined with differential pressure control strategies, can achieve significant energy savings at partial loads
  • Low Pressure Loss Duct Design: Reducing duct system pressure loss reduces the static pressure required by fans, directly lowering fan energy consumption

4. Automatic Controls and Advanced Energy-Saving Technologies

The EEWH EAC evaluation provides additional energy-saving coefficients for adopting automatic control strategies and advanced energy-saving technologies:

  • Economizer (Free Cooling): When outdoor air enthalpy is lower than return air, increasing outdoor air intake to reduce mechanical cooling load
  • CO₂-Based Demand-Controlled Ventilation: Adjusting fresh air volume based on actual occupancy density to avoid energy waste from excessive ventilation
  • Ice Storage Systems: Storing ice using off-peak electricity at night and melting ice for cooling during the day, reducing peak electricity demand
  • Energy Recovery Ventilators: Recovering cooling (or heating) energy from exhaust air to reduce outdoor air processing energy consumption

5. Certification Process and Practical Recommendations

EEWH green building certification is divided into "Candidate Green Building Certificate" (design stage) and "Green Building Label" (after completion)[4]. For HVAC system design:

  • EAC preliminary calculations should be conducted in the early design phase to confirm the HVAC system plan can achieve the target rating
  • Coordinate with architects on envelope design (ENVLOAD) — reducing HVAC load is the most fundamental energy-saving strategy
  • During equipment selection, require manufacturers to provide efficiency data that meets EAC calculation requirements
  • During construction, ensure equipment installation and control strategies comply with design specifications, otherwise completion verification may not pass

Conclusion

The EEWH green building label HVAC energy-saving metrics provide quantifiable energy-saving targets and an evaluation framework for HVAC system design. For HVAC engineers, familiarity with EAC calculation methods and influencing factors is essential for maintaining professional competitiveness in the green building era. In the next article, we will explore a topic more directly relevant to building owners — the application guide for 2026 commercial energy-saving subsidies.