Codes, Standards and Energy Efficiency
This domain tests which document governs which decision, and how efficiency ratings translate into real energy use.
Core rules
- ASHRAE 90.1 covers commercial and high-rise residential energy; the IECC and ASHRAE 90.2 cover residential. Local amendments override both.
- ASHRAE 62.1 and 62.2 set ventilation; NFPA 54 covers fuel gas, NFPA 90A and 90B cover air ducts and grease ducts, ASHRAE 15 and 34 cover refrigeration safety and refrigerant classification, and EPA 608 covers refrigerant handling.
- Equipment ratings use the current test standards: SEER2 and HSPF2 for unitary equipment, AFUE and thermal efficiency for heating, IEER for part-load commercial cooling.
- 90.1 includes prescriptive and performance paths, economizer requirements by climate zone and capacity, and commissioning requirements for larger buildings.
Worked example
A building needs 30 MMBtu of annual cooling. At SEER2 14.3, energy = 30,000,000 / 14.3 = 2,098 kWh per year. At SEER2 15.2, energy = 30,000,000 / 15.2 = 1,974 kWh, saving 124 kWh, about 6 percent. At 0.15 dollars per kWh that is about 19 dollars per year per unit. Multiply across the building and compare to installed cost, and the reasoning becomes a lifecycle decision rather than a nameplate comparison.
Traps that cost marks
- Quoting SEER when the compliance path requires SEER2.
- Applying 90.1 to a single-family house or a low-rise residential project.
- Treating code minimum as good design rather than a floor.
- Missing economizer exceptions based on climate zone and capacity.
- Citing a standard without checking the adopted edition and local amendments.