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HVAC General Requirements
All of the applicable general requirements from the 2000 International Energy Conservation Code must be met regardless of which compliance method is chosen.
- HVAC efficiency requirements
- Temperature controls
- HVAC piping insulation
- Duct insulation
- Duct construction
- Summary
- Test your knowledge
- Additional resources
An HVAC system consists of:
- a heating and/or cooling source,
- a distribution system (e.g., ductwork or hot/chilled water piping), and
- temperature controls.
HVAC Efficiency Requirements
- The National Appliance Energy Conservation Act (NAECA) supersedes the minimum efficiency requirements addressed in the IECC.
- NAECA applies to heating, cooling, and water-heating systems.
- Manufacturers must comply with NAECA, so equipment purchased by a builder should automatically comply with the provisions.
Get more details on HVAC equipment efficiency terms
Temperature Controls
Thermostats are required for each separate HVAC system. They must be adjustable and be able to accommodate the following temperature ranges:
- Heating only, 55-75°F
- Heating and cooling, 55-85°F
- Cooling only, 70-85°F
Thermostats must be able to reduce temperatures during periods of non-use by either manually adjusting the temperature upward or downward or shutting the system off entirely.
Heat Pumps
Heat pump thermostats are required to be capable of preventing supplementary heating when the heating load can be met by the heat pump alone
- supplemental heater operation is only allowed during the outdoor coil defrost cycles and is not to exceed 15 minutes
The supplemental heater isn't as efficient, so the less it is used, the more energy that will be saved.
Humidity Control
Humidistats used for comfort shall be capable of being set to prevent the use of fossil fuel or electricity to reduce relative humidity below 60 percent or increase relative humidity above 30 percent. The intent is to limit the energy used for humidification until the level in the space falls below 30 percent.
HVAC Piping Insulation
The requirements in the table apply to HVAC piping located in unconditioned space and conveying fluids > 120°F and < 55°F. Typically, this will apply to refrigerant piping and water piping for hydronic heating systems.
Minimum HVAC Piping Insulation Thickness
| PIPING SYSTEM TYPES | FLUID TEMP RANGE, °F | PIPE SIZESa | |||
|---|---|---|---|---|---|
| Runouts up to 2in.b | 1 in. and less | 1.25 in. to 2 in. | 2.5 in. to 4 in. | ||
| HEATING SYSTEMS | |||||
| Low Pressure/Temperature | 201-250 | 1.0> | 1.5 | 1.5 | 2.0 |
| Low Temperature | 120-200 | 0.5 | 1.0> | 1.0 | 1.5 |
| Steam Condensate (for feed water) | Any | 1.0 | 1.0 | 1.5 | 2.0 |
| COOLING SYSTEMS | |||||
| Chilled Water, Refrigerant, and Brine | 40-55 | 0.5 | 0.5 | 0.75 | 1.0 |
| Below 40 | 1.0 | 1.0 | 1.5 | 1.5 | |
a. For piping exposed to outdoor air, increase insulation thickness by 0.5 inch.
b. Runouts not exceeding 12 feet in length to individual terminal units.
Duct Insulation
Duct insulation requirements in the IECC depend on the location of the building (HDD), the type of duct, and the location of the ducts.
| - | Insulation R-values (h×ft2×°F)/Btu | |||
|---|---|---|---|---|
| Ducts in unconditioned attics or outside building | Ducts in unconditioned basements, crawl spaces, garages and other unconditioned spaces | |||
| Annual Heating Degree Days | Supply | Return | Supply | Return |
| Below 1,500 | 8 | 4 | 4 | 0 |
| 1,500 to 3,500 | 8 | 4 | 6 | 2 |
| 3,501 to 7,500 | 8 | 4 | 8 | 2 |
| Above 7,500 | 11 | 6 | 11 | 2 |
An example of a sealed duct that is marked with the insulation level.
Duct Construction
Ductwork must be constructed in accordance with the International Mechanical Code. All joints, seams, and connections must be securely fastened with welds, gaskets, mastics (adhesives), mastic-plus-embedded-fabric, or tapes. "Duct tape" has a lot of great uses, but sealing ducts isn't one of them, so it is not permitted. Tapes and mastics used with rigid fibrous glass ducts must be labeled in accordance with UL 181A. Tapes and mastics used with flexible air ducts must be labeled in accordance with UL 181B.
- Exception:
Continuously-welded and locking-type longitudinal joints and seams on ducts operating at less than 2 in. w.g. (water gauge) (500 Pa).
Summary
- Manufacturers must comply with NAECA, so HVAC equipment purchased by builders should automatically comply with code requirements.
- Thermostats are required for each separate HVAC system.
- The 2000 IECC has minimum insulation thicknesses for HVAC piping by type of piping system, pipe size, and fluid temperature range.
- Duct insulation requirements in the IECC depend on the location of the building (HDD), the type of duct, and the location of the ducts.
- All duct joints, seams, and connections must be securely fastened with welds, gaskets, mastics (adhesives), mastic-plus-embedded-fabric, or tapes. "Duct tape" is not permitted.
Test your knowledge
The 2000 IECC has no special requirements for heat pump thermostats.
Need to review?
Additional Resources:
- EEBA's "It's Just a Duct" Course
- LBNL's Residential Ducts Program
- DOE's "Better Duct Systems for Home Heating and Cooling" Manual (12.5 MB)
Questions or comments? Send an e-mail.
