CLTD Wall Roof Cooling Load Calculator

Building Envelope Heat Gain: Calculate instantaneous thermal conduction and solar storage cooling loads using ASHRAE CLTD corrections.

Surface Area $A$ (ft²):

U-Factor (Btu/hr·ft²·°F):

Envelope Component & Orientation:

Indoor Design $T_{in}$ (°F):

Outdoor Peak $T_{out}$ (°F):

Daily Range $DR$ (°F):

Surface Color Adjustment:

Peak Cooling Load ($q$)

-- Btu/hr

Cooling Tons: -- TR

Corrected CLTD ($CLTD_{corr}$)

-- °F

Base CLTD: -- °F

Heat Flux per Area

-- Btu/(hr·ft²)

In SI: -- W/m²

Outdoor Mean Temp

-- °F

Steady-State ΔT: -- °F

ASHRAE CLTD Formulation:

• $CLTD_{corr} = [CLTD + (78 - T_{in}) + (T_{out,m} - 85)] \cdot K_{color}$.

• Dynamic thermal mass delays peak heat transmission by $2$ to $8$ hours relative to solar noon.

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