Carrier SDL 6.4: System-Based HVAC Load Calculation Software

SDL 6.4 (System Design Load) is Carrier's latest version of the professional HVAC load calculation program, released as part of the eDesign Suite alongside HAP 6.4 . It uses ASHRAE Heat Balance methodology and system-based design principles to accurately size commercial building HVAC systems .

Key Features

System-Based Load Calculation

• ASHRAE Heat Balance Method: Calculates design cooling and heating loads using industry-standard algorithms for peak load analysis

• System-Specific Sizing: Tailors calculations for individual system types—Single Zone CAV, VAV, Fan Powered Mixing Box, VRF, induction, fan coils, PTACs, water-source/ground-source heat pumps, chilled beams

• Complete Psychrometrics: Altitude-adjusted analysis with dehumidification controls, economizers, and heat reclaim

Building & Component Modeling

• 3D Building Modeling: Same as HAP v6; supports sloped roofs, skylights, external shading, and 16 principal exposures

• Construction Libraries: Pre-defined wall, roof, window, and interior shading constructions with custom entry options

• Scheduling: Equipment operation from 1-24 hours; hourly scheduling for lights, occupancy, appliances, and thermostats

Advanced Analysis

• Morning Pulldown: Calculates recovery loads after nighttime setbacks

• Return Plenum & Duct Leakage: Models realistic system losses

• Thermostat Throttling: Accounts for control band effects on zone loads

• Outdoor Ventilation: ASHRAE Standards 62.1 (2004–2019 editions)

Technical Specifications