Load Calculation Q1-Wall (1)

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Concordia University *

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463

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Mechanical Engineering

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Oct 30, 2023

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Cooling Load Calculation - CLTD Method (Walls, Roofs, Windows, and Doors) ? ?,???? ? = ෍ 1 ? q ? (?) + ? ??? ? + ? 𝑖?? ? ?𝑖?ℎ??,??????,???𝑖????? +? 𝑖?? ? q ? = walls, windows, roof q 𝑖?? = internal loads, people, lights, equipment) q 𝑖?? = air infiltration q ??? = solar gains

Example: Cooling Load from Exterior Walls Given Data • West Wall Construction Details : • 4 in. heavy concrete • 2 in. insulation (high density) on outside • outside finished with stucco • inside finished with gypsum board • Calculate the cooling load per ft 2 of the west wall at 1700h for indoor temp. of 79 F Outdoor Design Day Data • outdoor design temps are given in Table C-1 for various locations: • For the given location • t o = 94 ̊F and DR = 30 ̊F 2 OA Temp t o 𝐷𝑅 2 t o (max temp) and DR are given in Table C-1 for various locations BLDG 471 Fall 2023 Dr. M. Zaheeruddin

Solution: ሶ? ? ? = ?? ?𝐿?? ? ??? 3 𝑅 = ฏ 𝑅 0 ??????? ?𝑖?? + ฏ 𝑅 ? ?????? + ฑ 𝑅 𝑖?? 𝑖??????𝑖?? + ฏ 𝑅 ? ℎ???? ???????? + ฏ 𝑅 ? ?????? + ฎ 𝑅 𝑖 𝑖??𝑖?? ?𝑖?? ? 0 + ? 1 + ? 6 + ? 5 + ? 1 + ? 0 = 0.33 + 0.21 + ถ 6.67 ൰ ℎ𝑖?ℎ ???𝑖?? 𝑖??????𝑖?? (????=1.0 ?? ?? 2 + 0.33 + 0.15 + 0.69 = 8.37 𝑅 = ??? ℎ?𝑓? 2 ℉ −1 𝑅 = 8.37 ℎ?𝑓? 2 ℉ ??? ֜ ? = 1 𝑅 Step 1 : Determine the R value of the wall using material properties listed in Table 8-21. BLDG 471 Fall 2023 Dr. M. Zaheeruddin

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4 BLDG 471 Fall 2023 Dr. M. Zaheeruddin

Step 2 Find the ASHRAE Wall Type Number from Tables 8-22a,b,c Determine the Wall Type Wall type depends on: 1) mass placement with respect to insulation 2) overall R-value 3) principal wall material 4) secondary material (gypsum etc.) • Mass placement: inside insulation, i.e. mass is towards the conditioned space • R-value: 8.37 ℎ??? 2 ℉ 𝐵?? • Principal wall materials are: • i) the massive wall materials ii) non massive wood layers B 7 , B 8 , B 9 iii) non massive steel layer A 3 5 BLDG 471 Fall 2023 Dr. M. Zaheeruddin

From Table 8-22a (mass located inside insulation), with principal wall material = heavy concrete C 5 (Table 8-21a), secondary wall material = stucco, and 𝑅 = 8.37 ℎ??? 2 ℉ 𝐵?? We have Wall Type = 7 Wall Type BLDG 471 Fall 2023 Dr. M. Zaheeruddin 6

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7 ?𝐿?? ? ??? = ?𝐿?? + 78 − ? 𝑖 + ? ?? − 85 From Table 8-19, for the west wall: ?𝐿?? 17 = 34℉ 𝑎? 1700 ℎ ሶ? ? 17 = ?? ?𝐿?? 17 ??? = 1 8.37 ∗ 1 ∗ 27 = 3.22 𝐵?? ℎ? at 1700 h ?𝐿?? 17 ??? = 34 + 78 − 79 + 94 − 30 2 − 85 = 34 − 1 − 6 = 27℉ Step 3 ▪ Determine CLTD and Cooling Load ▪ For West wall Type 7, from Table 8-19, CLTD at 17 h = 34 F ▪ Determine the corrected CLTD value and calculate the cooling load as shown below BLDG 471 Fall 2023 Dr. M. Zaheeruddin 1 Watt = 3.412 BH ሶ? 𝒘 𝒕 = ?𝑨 ?𝑳?? 𝒕 𝒄𝒐?