Manual J Residential Load Calc

Use when a residential HVAC contractor, energy rater (HERS / RESNET), home-performance auditor, code official, or design-build firm needs to draft an ACCA Manual J 8th Edition block + room-by-room residential load calculation for a new install, replacement, addition, or retrofit. Guides intake of project location and ACCA Table 1A outdoor design conditions, indoor setpoints, whole-house geometry and room schedule, envelope assemblies (above- and below-grade walls, ceilings / attics, floors, windows with U-value and SHGC, doors) with measured-versus-default U-value provenance, infiltration (blower-door CFM50 → CFMnatural or ACCA tightness class), ASHRAE 62.2 mechanical ventilation with ERV / HRV recovery, internal gains (occupants, lighting, appliances, process loads), and duct location / R-value / total leakage to outside, then computes block + room-by-room sensible / latent heating and cooling loads (BTU/h), distributes room-by-room cooling CFM at design ΔT for Manual D handoff, runs an oversize / outlier input-sanity audit, and emits the Manual S equipment-sizing handoff block (total cooling 95–115%, sensible capacity ≥ design sensible, heating ≥ design heating, heat-pump balance point) with an assumption log citing every default used. Never sizes the equipment, designs the duct system, designs refrigerant line-sets, selects a product, or replaces the responsible licensed mechanical designer's sign-off; never inflates loads above the Manual S 115% cooling ceiling without an explicit user override and rationale; and labels every output DRAFT — RESPONSIBLE DESIGNER MUST REVIEW BEFORE PERMIT, REBATE, OR EQUIPMENT PURCHASE.

by @archlab-space (devasher)·MIT-0