24-Bld-A4 Building Environmental Control Systems · May 2017

Question 7 of 14: Classroom Outdoor Air Rate

Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)

Notes on this paper

National Exams May 2017 — 07-Bld-A4, Building Environmental Control Systems (Building Engineering). 3-hour closed-book exam: Section 1 (four 20-mark essay/calculation questions) + Section 2 (ten 2-mark multiple-choice questions).

Reference texts: ASHRAE Handbook — Fundamentals (2021 ed.); ASHRAE Standard 62.1, Ventilation for Acceptable Indoor Air Quality (2022 ed.); McQuiston, Parker & Spitler, Heating, Ventilating, and Air Conditioning: Analysis and Design (6th ed.); National Building Code of Canada 2020 (NBCC); National Energy Code of Canada for Buildings 2020 (NECB).

Question 2.3: Classroom Outdoor Air Rate (2 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

Given/Find. ASHRAE 62.1 breathing-zone outdoor air $V_{bz}=R_p P_z + R_a A_z$. Floor area $A_z=8\times10=80$ m² (the 3.5 m ceiling height is not needed for this per-person/per-area formula). Occupancy $P_z = 55/100\times80=44$ persons.

1. Apply the ASHRAE 62.1 formula. $$V_{bz}=3.8\times44+0.3\times80=167.2+24.0=191.2\ \text{L/s}$$
2. Convert to m³/hr (1 L/s = 3.6 m³/hr): $$\boxed{191.2\times3.6=688.3\ \text{m}^3/\text{hr}}$$

Final Result

Answer: (c) 688.3 m³/hr

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