Free Practice Questions for Iran Nezam Mechanical Design Exam
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Key Facts: Iran Nezam Mechanical Design Exam Exam
60 MCQs
Exam Questions Count
Office of National Building Regulations (inbr.ir)
180 Min
Total Testing Time
inbr.ir Examination Bylaws
50%
Passing Score (Net with Negative Marking)
Clause 6-4 of Official Registration Guideline
Open Book
Permitted Testing Format
Ministry of Roads & Urban Development
The Iran Construction Engineering Organization Mechanical Design written paper is a 180-minute, 60-MCQ open-book licensure examination with negative marking (1/3 penalty per wrong answer) requiring a net score of 50%, and is followed by a compulsory scientific interview before the pass is confirmed. It tests INBR Topics 14 (HVAC), 16 (Plumbing/Sanitary), 17 (Natural Gas), 3 (Fire Suppression), and 19 (Energy Efficiency). This 100-question multiple-choice bank is an independent English-language engineering adaptation featuring worked numerical solutions to prepare candidates for the demanding calculation and code-lookup requirements.
Sample Iran Nezam Mechanical Design Exam Practice Questions
Try these sample questions to review concepts for the Iran Nezam Mechanical Design Exam exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.
1An exterior perimeter wall of an office building in Tabriz has a net surface area of 40 m² and an overall heat transfer coefficient (U-value) of 0.45 W/(m²·K). If the indoor winter design temperature is 21°C and the outdoor winter 99% design dry-bulb temperature per INBR Topic 14 is -5°C, what is the design steady-state transmission heat loss through this wall?
2A corner conference room with an internal volume of 180 m³ experiences air infiltration evaluated by the air change method per INBR Topic 14. The design infiltration rate is 0.8 air changes per hour (ACH). Given an indoor design temperature of 20°C and an outdoor design temperature of -4°C, what is the sensible heat loss due to infiltration? (Use standard volumetric heat capacity of air = 0.34 W·h/(m³·K) or 1.21 kJ/(m³·K)).
3An air handling unit (AHU) in a commercial building in Tehran introduces a dedicated outdoor air ventilation flow rate of 600 L/s (0.6 m³/s). Outdoor design air enters the preheat coil at -2°C and must be heated to the room supply neutrality temperature of 22°C. Taking standard air density ρ = 1.20 kg/m³ and specific heat cp = 1.005 kJ/(kg·K), what is the required heating coil thermal capacity?
4An air handling unit mixes recirculated return air and fresh outdoor air. The return airflow is 3,000 L/s at 24°C dry-bulb and 50% relative humidity, while the outdoor airflow is 1,000 L/s at 36°C dry-bulb and 30% relative humidity. Assuming adiabatic mixing at standard atmospheric pressure, what is the resulting mixed air dry-bulb temperature?
5A cooling load calculation for an auditorium per INBR Topic 14 yields a peak room sensible cooling load of 42 kW and a peak room latent cooling load of 14 kW. What is the Room Sensible Heat Ratio (RSHR)?
6A conditioning zone has a design sensible cooling load of 28 kW. The indoor design condition is 24°C dry-bulb and the supply air is delivered from the diffuser at 14°C dry-bulb. Taking air density as 1.20 kg/m³ and specific heat cp as 1.005 kJ/(kg·K), what is the required supply airflow rate in cubic meters per second?
7Air enters a chilled water cooling and dehumidifying coil at 28°C dry-bulb and leaves the coil at 14°C dry-bulb. If the Apparatus Dew Point (ADP) of the cooling coil surface is 10°C, what is the coil bypass factor (BF)?
8A south-facing external window with clear double glazing in Shiraz has an area of 15 m² and a Solar Heat Gain Coefficient (SHGC) of 0.40. At the design peak cooling hour in July, the incident solar radiation on the south facade is 650 W/m². Neglecting internal shading, what is the instantaneous solar radiation heat gain transmitted through this window?
9A rectangular air distribution duct has cross-sectional dimensions of a = 600 mm and b = 300 mm. Using the standard Huebscher circular equivalent formula cited in INBR Topic 14 (De = 1.30 * (a * b)^0.625 / (a + b)^0.25), what is the circular equivalent diameter De for equal friction and volumetric flow?
10A main supply air duct in an office building is sized using the Equal Friction Method per INBR Topic 14 at a design friction rate of 1.0 Pa/m (approx. 0.12 in. w.g. per 100 ft). If the total equivalent length of the longest index run (including straight ductwork, elbows, take-offs, and transitions) is 65 meters, what is the total duct friction pressure loss?
About the Iran Nezam Mechanical Design Exam Exam
The Iran Construction Engineering Organization Mechanical Design Licensure Examination (آزمون ورود به حرفه مهندسان تأسیسات مکانیکی — صلاحیت طراحی) is the mandatory professional certification for mechanical engineers seeking statutory license Grade 3 (پایه ۳) to design building engineering systems across the Islamic Republic of Iran. Governed by the Ministry of Roads and Urban Development through the Office of National Building Regulations and Building Control (inbr.ir) and administered via Sazman-e Sanjesh, the exam tests comprehensive mastery of Iranian National Building Regulations (INBR / مباحث مقررات ملی ساختمان). The syllabus rigorously assesses HVAC central plants and air distribution (Topic 14), domestic water and sanitary drainage (Topic 16), natural gas piping networks (Topic 17), life safety and fire sprinkler systems (Topic 3), and thermal energy efficiency (Topic 19). Although candidates may bring physical copies of official code books and approved non-programmable engineering calculators into the exam hall, the tight 180-minute window for 60 questions with negative marking demands rapid formula retrieval, high numerical accuracy, and deep fluency in code-specified equations. Since the 1404 sittings, passing the written paper in the design (طراحی) qualification is no longer sufficient on its own: invited candidates must also pass a compulsory scientific interview (مصاحبه علمی) before the result is confirmed. This question bank is an independent English-language multiple-choice study adaptation by OpenExamPrep; it is not an official translation, a simulation of the interview stage, or a released past paper.
Exam sponsor: Office of National Building Regulations and Building Control (inbr.ir), Ministry of Roads and Urban Development; delivered nationwide by the National Organization for Educational Testing (Sazman-e Sanjesh) educational services company. The requirements and fees below concern the certification or admission exam, separate from our free practice resources.
Assessment
Two stages. Stage 1: a written paper of 60 four-option multiple-choice questions covering HVAC design (Topic 14), plumbing and sanitary systems (Topic 16), natural gas piping (Topic 17), fire suppression systems (Topic 3), and energy conservation (Topic 19). Stage 2: a compulsory scientific interview (مصاحبه علمی) held at the provincial Roads and Urban Development office, covering the same code sources plus practical use of a design software package chosen by the candidate. Failure or non-attendance at the interview voids the written pass.
Time Limit
180 minutes
Passing Score
50 out of 100 (50%) — clause 6-4 of the official 1405 registration instruction, calculated after the negative-marking deduction
Exam / Certification Fees
Set per sitting and shown in the inbr.ir registration cart; the official 1405 registration instruction does not publish a fixed amount
Exam sponsor websiteFees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.
Our practice resources: topics covered
We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.
HVAC Systems & Psychrometric Design (INBR Topic 14)
Heating load calculation (conduction, infiltration, ventilation), cooling load (solar, sensible, latent), psychrometric processes, air distribution duct sizing by equal friction and static regain, hydronic piping, chiller/boiler selection, circulating pump head, and expansion tank sizing.
Plumbing & Sanitary Systems (INBR Topic 16)
Domestic water supply sizing using Water Supply Fixture Units (WSFU) and Hunter curves, booster pump sizing, storage cisterns, domestic hot water generation, sanitary drainage using Drainage Fixture Units (DFU), vent stacks, grease interceptors, sewage ejectors, and stormwater drainage.
Natural Gas Piping Design (INBR Topic 17)
Low-pressure (1/4 psi) and medium-pressure (2 psi) natural gas piping design, Pole's formula and pressure drop tables, appliance gas consumption (kcal/hr and m3/hr), meter room ventilation, regulator selection, and venting of combustion products.
Fire Suppression & Sprinkler Systems (INBR Topic 3)
Automatic fire sprinkler systems design, hazard classifications, design density and area of operation, sprinkler head K-factors, hydraulic discharge formula Q = K * sqrt(P), standpipe classes I, II, and III, and fire pump hydraulic sizing.
Energy Conservation & Equipment Sizing (INBR Topic 19)
Building envelope overall thermal transmittance (U-values), thermal inertia, solar heat gain coefficient (SHGC), equipment efficiency thresholds (COP, EER), and duct/pipe insulation thickness standards.
Preparing for the Iran Nezam Mechanical Design Exam Exam
What You Need to Know
- Passing score: 50 out of 100 (50%) — clause 6-4 of the official 1405 registration instruction, calculated after the negative-marking deduction
- Assessment: Two stages. Stage 1: a written paper of 60 four-option multiple-choice questions covering HVAC design (Topic 14), plumbing and sanitary systems (Topic 16), natural gas piping (Topic 17), fire suppression systems (Topic 3), and energy conservation (Topic 19). Stage 2: a compulsory scientific interview (مصاحبه علمی) held at the provincial Roads and Urban Development office, covering the same code sources plus practical use of a design software package chosen by the candidate. Failure or non-attendance at the interview voids the written pass.
- Time limit: 180 minutes
- Exam / certification fees: Set per sitting and shown in the inbr.ir registration cart; the official 1405 registration instruction does not publish a fixed amount Official sources
Using Our Practice Resources
- Work through all 100 available questions
- Review every answer and explanation
- Track weak areas and revisit them
- Use our AI tutor for tough concepts
Iran Nezam Mechanical Design Exam: Suggested Study Strategy
Frequently Asked Questions
What is the official format and duration of the Iran Nezam Mechanical Design examination?
The examination consists of 60 four-option multiple-choice questions administered over a single 180-minute testing session (averaging 3 minutes per question). The examination is conducted in person nationwide by the National Organization for Educational Testing (Sazman-e Sanjesh).
Is the examination open book and what materials are allowed?
Yes, the examination is completely open book (کتابباز). Candidates are permitted to bring physical copies of all official Iranian National Building Regulations (مباحث مقررات ملی ساختمان), standard engineering handbooks, code commentaries, notes, and approved non-programmable engineering calculators into the examination center. Electronic devices, laptops, tablets, and mobile phones are strictly prohibited.
How does negative marking operate under the official scoring rules?
Negative marking is strictly applied at a rate of 1/3 point deducted for each incorrect answer. That is, every three incorrect responses cancel out one correct response. Unanswered questions receive zero points. The final percentage score is computed as: [(Correct Answers - (Incorrect Answers / 3)) / Total Questions] * 100. To pass, a net score of at least 50.0% is required.
Which National Building Regulation (INBR) topics form the core syllabus for Mechanical Design?
The mechanical design syllabus is anchored on five primary volumes: Topic 14 (Heating, Ventilating, and Air Conditioning / تاسیسات مکانیکی), Topic 16 (Plumbing and Sanitary Systems / تاسیسات بهداشتی), Topic 17 (Natural Gas Piping for Buildings / لولهکشی گاز طبیعی), Topic 3 (Building Fire Protection / حفاظت ساختمانها در مقابل حریق), and Topic 19 (Energy Efficiency / صرفهجویی در مصرف انرژی). In addition, foundational knowledge of Topic 12 (Construction Safety) and general building standards is occasionally examined.
What calculator model is permitted in the examination room?
Standard non-programmable scientific calculators (such as Casio fx-82, fx-991ES Plus, or fx-991EX ClassWiz without text storage or wireless connectivity) are permitted. Calculators capable of storing text, wireless communication, or running symbolic algebra programs are confiscated by test proctors.
Does this English-language question bank replace the official Persian code books?
No. The official licensure examination conducted by inbr.ir is presented in Persian. This practice bank is an independent technical English adaptation designed for engineering graduates, international practitioners, and candidates who want to practice core design calculations, formula applications, and engineering principles based on the exact INBR standards.