Manual J calculator · SC
Manual J load calculation for South Carolina.
Reference data for Manual J load calculations in South Carolina: ASHRAE design temperatures for 4 top metros, energy code status, and SC LLR licensing. The calculator does not load this page's data. It asks for your project location and looks up outdoor design conditions in its own dataset, by IECC 2021 climate zone for a ZIP code or by weather station for the 10 major metros in its city list.
Reference metro
Charleston, SC (Charleston County) · IECC 2015 zone 3A · winter 99% DB 31°F · summer 0.4% DB 94°F · MCWB 78°F.
0.4% DB: ASHRAE 2021 station value · Manual J 8 loads use the 1% DB
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01 · ASHRAE design conditions
Top 4 metros in South Carolina - ASHRAE design temperatures.
These are the ASHRAE 99% heating and 0.4% cooling design temperatures, not the absolute extremes. Outdoor temperatures go past the 0.4% cooling value about 35 hours per year and below the 99% heating value about 88 hours per year.
Manual J 8th edition load calculations use the 1% cooling and 99% heating design temperatures. For ENERGY STAR new homes, the EPA recommends "the ACCA Manual J, 8th edition, 1% cooling season design temperature and 99% heating season design temperature for the weather station that's geographically closest to the home" ( ENERGY STAR, Design Temperature Limits). For the same station the 1% cooling value is exceeded about 88 hours a year, against about 35 for the 0.4% value, so it is the lower of the two, and the table's cooling column is not the Manual J design temperature.
| Metro | County | Zone (IECC 2015) | Winter 99% DB | Summer 0.4% DB | MCWB |
|---|---|---|---|---|---|
| Charleston | Charleston County | 3A | 31°F | 94°F | 78°F |
| Columbia | Richland County | 3A | 27°F | 97°F | 75°F |
| Greenville | Greenville County | 3A | 25°F | 94°F | 73°F |
| Myrtle Beach | Horry County | 3A | 28°F | 91°F | 77°F |
Design temperatures are single station values from the ASHRAE 2021 Climatic Design Conditions (99% heating, 0.4% cooling), one airport station per metro, in whole °F within 1°F. DB = dry-bulb. MCWB = mean coincident wet-bulb at the 0.4% cooling design hour.
Zones in this table are from the IECC 2015 county map (PNNL county data). For a ZIP code, BuildSolver's calculator assigns zones by the IECC 2021 county map, which gives the same zones for these counties. A ZIP code near a zone line can get the neighboring zone.
02 · Energy code
Energy code baseline in South Carolina is IECC 2009 (residential, no state amendments).
In effect since 2013. Manual J load-calc documentation requirements flow from the state energy code; verify your specific AHJ's submittal rules before relying on the baseline.
- South Carolina's residential energy code is the 2009 IECC, effective January 1, 2013, with no state amendments (DOE Building Energy Codes Program) - among the older active baselines in the country.
- Verify the current baseline with the local building department before relying on it for a specific job.
Code status from DOE Building Energy Codes Program - South Carolina status, verified October 6, 2026.
03 · South Carolina HVAC labor data
BLS wages and employment for HVAC mechanics in South Carolina.
These are state-level wages for occupation code 49-9021 - Heating, Air Conditioning, and Refrigeration Mechanics and Installers - from the most recent BLS Occupational Employment and Wage Statistics release.
- Median hourly wage
- $27.22
- Mean annual wage
- $56,460
- Employment estimate
- 6,920
Wage figures from BLS OEWS May 2025, SOC 49-9021 (state-level), released May 15, 2026.
04 · License & permit
HVAC licensing in South Carolina runs through SC LLR.
State-level HVAC contractor licensing is administered by the South Carolina Department of Labor, Licensing & Regulation - Contractor's Licensing Board. Licenses renew every 2 years.
License types
- Mechanical Contractor - Air Conditioning (commercial)
- Residential Specialty Contractor - HVAC
Permits
SC requires a mechanical permit for new HVAC installation and most change-outs in jurisdictions with active inspection programs (all major metros). Permit thresholds and CE requirements differ between commercial and residential specialty licenses.
A replacement install typically requires a permit as well.
Coastal SC jurisdictions (Horry, Charleston) may add wind-load requirements for outdoor equipment; confirm with the local building department before purchasing equipment.
05 · FAQ
Common Manual J questions for South Carolina contractors.
+How important is latent load in coastal South Carolina?
Charleston and Myrtle Beach both sit at 77-78°F summer design wet-bulb - among the highest sustained latent loads in the U.S. Sensible-only Manual J sizing under-equips dehumidification by 15-20% in coastal SC. The Manual J 8th-edition latent calculation (§8) is critical, and BuildSolver runs it automatically.
+Why is SC still on IECC 2009?
The 2009 IECC is still the residential energy code in force statewide (DOE Building Energy Codes Program). Always verify the current baseline with the AHJ before assuming.
+Does Charleston have hurricane-zone requirements for HVAC?
Wind and flood requirements for outdoor equipment come from the local building code and floodplain rules, so confirm them with the Charleston, Horry, or Beaufort building department. The Manual J sizing itself is unaffected.
+What's the average HVAC wage in South Carolina?
BLS OEWS May 2025 (released May 15, 2026) reports a $27.22/hr median for SC HVAC mechanics and installers, with an annual mean of $56,460. The national median is $29.33/hr.
+Can BuildSolver document a Manual J for an SC permit?
No. BuildSolver is not ACCA-approved for permit submission. Use its output for sales-phase sizing and client quotes, and produce the permit submittal in ACCA-approved software such as Wrightsoft Right-J8 or Cool Calc Manual J. Verify documentation requirements with the specific building department; SC's older code baseline means documentation requirements vary by jurisdiction.
+Why is Greenville heating-dominant compared to Charleston?
Greenville sits in the Upstate at higher elevation - winter design DB is 25°F vs Charleston's 31°F. Manual J heating loads for the same building in Greenville run about 15% higher than in Charleston (a 45°F against a 39°F design difference at 70°F indoors). Equipment selection often shifts toward heat-pump dual-fuel in the Upstate, while coastal SC stays heat-pump-only.
Try a South Carolina load calculation now.
The chat will ask follow-up questions like an experienced engineer - square footage, construction type, window count, insulation level - and run the Manual J on your inputs. Outdoor design conditions come from its own dataset (by IECC 2021 climate zone for a ZIP code, by weather station for the 10 major metros in its city list), not from the metro table on this page.
Start South Carolina calculationRelated · same climate zone
Other states with similar ASHRAE climate zones.
Climate-driven Manual J inputs such as infiltration, latent share, and design temperatures behave similarly across states that share a climate zone. Each page below gives that state's own design temperatures and licensing context. Zones combine the IECC 2015 and IECC 2021 county maps.
Data last reviewed October 16, 2026 · underlying sources as of May 15, 2026