Utilisation & Building Services MCQ – 34 previous year questions with solutions

D — Fluorescent lamp. Its long tube gives wide, diffuse, low-glare light with much better luminous efficacy than incandescent lamps.

D — Halogen lamp. It is an improved incandescent source with a halogen regenerative cycle, giving high filament temperature, stable output, ~3200 K colour temperature and CRI close to 100.

C — Lux. Illuminance is luminous flux falling per unit area: 1 lux = 1 lumen/m².

Modern industrial LEDs provide high luminous efficacy and long service life compared with older mercury-vapor technology. Suitable luminaires can also provide high CRI, so poor color rendering is not an inherent LED limitation; inspection areas can be designed with high-CRI LED sources. Key relation: Luminous efficacy=lumens/electrical watt.

Exam focus: Check efficacy, lifetime, CRI and glare together. Common trap: LED does not automatically mean poor CRI.

A luminaire is the complete lighting unit/fixture: it includes the lamp or LED light source together with housing, optical components, electrical gear/driver and parts needed to distribute, position and protect the light source.

A — Bluish-white. Mercury emission lines are mainly in the blue-green-violet region with almost no red, so the light appears bluish-white.

The luminaire is 4 ft below a 16-ft ceiling and the work plane is 4 ft above the floor, so cavity height is 8 ft. Room cavity ratio is RCR=5h(L+W)/(LW). Substituting h=8 ft, L=120 ft and W=60 ft gives RCR=1.0, matching option B.

B — Thermal insulation. The evacuated outer envelope keeps the discharge tube hot enough to vaporise sodium and protects the inner tube; it is not the light source.

LED luminaires are the dominant high-efficiency choice for new street-lighting projects because they provide high luminous efficacy, long life, controllability, good optical directionality and lower maintenance compared with legacy discharge lamps.

An AV system typically controls presentation displays/projectors, screens, conferencing and audio/background-music equipment. Fire-hydrant pressure belongs to the fire-protection/mechanical monitoring system, not the AV system.

A Building Management System (BMS) is the supervisory 'brain' used to monitor and control multiple building services such as HVAC, ventilation, lighting, pumps and electrical-energy systems through sensors, controllers and a central interface.

Smart Building Energy Automation integrates monitoring, control, communication and optimization of building loads and may coordinate local generation and storage. The first statement excludes battery management from a complete energy-management system and is therefore not a correct description; the second statement is consistent with smart-building automation. The resulting combination is option A.

In a ring topology, each network node is connected to two neighboring nodes so the links form a closed loop/circular path. Data travels around the ring according to the network's access/protocol design.

Modern office/building LANs commonly use switched Ethernet in a star topology. Fiber is favored for high-bandwidth or long backbone links and for immunity to electromagnetic interference. Key relation: Ethernet switch: primarily Layer 2; fiber backbone: high bandwidth and EMI immunity.

Exam focus: Distinguish a switch from a hub/repeater in OSI-layer questions. Common trap: A normal Ethernet switch is not principally a Layer-1 device.

Most common phone charging pads transfer energy by electromagnetic induction between a transmitter coil in the pad and a receiver coil in the device, often with resonant compensation to improve coupling and efficiency.

Addressable fire-alarm systems assign an identity/address to each detector or module, enabling the panel to locate the initiating device. Kitchens are prone to nuisance alarms from cooking aerosols, so detector selection is application-specific and heat detection is often preferred over a sensitive ionization smoke detector.

Exam focus: Choose detector type for the environment, not just sensitivity. Common trap: Ionization smoke detectors are not generally the preferred kitchen solution for avoiding false alarms.

A fireman's/fire lift is a specially arranged lift for fire-service use in high-rise buildings, with protected controls/access, clear identification and emergency-power arrangements so it remains available during a fire when normal services may fail. Exact installation details should be checked against the applicable NBC/local adoption.

Exam focus: Treat fire lift as a life-safety system, not an ordinary passenger lift. Common trap: Do not omit emergency power/identification requirements.

NBC 2016 defines a refuge area as a designated safe area within a high-rise building where occupants can temporarily assemble or wait during an emergency before rescue or further evacuation. It is a life-safety provision, which is the description given by option A.

A Manual Call Point (MCP) lets an occupant manually initiate the fire alarm after discovering a fire or dangerous condition. Activating it sends an alarm signal to the fire alarm control panel.

The lift governor is an overspeed-sensing safety device. If car speed exceeds its permitted value, the governor trips the safety mechanism so the car's safety gear/brake can grip the guide rails and stop the lift.

A common commercial escalator inclination is about 30° to the horizontal. This provides a practical compromise between vertical rise, passenger comfort, safety and floor-space requirements.

The counterweight balances the lift car plus a designed fraction of rated load, reducing the traction motor torque and energy needed to move the system. It also helps maintain traction on the sheave.

Centrifugal pumps require sufficient pressure at the suction to avoid local vaporization and cavitation; this is evaluated using NPSH. When a pump is above the liquid level, the casing/suction line must be primed because a centrifugal pump cannot normally evacuate air and establish suction by itself.

Exam focus: Cavitation questions: compare available and required NPSH. Common trap: Priming is unnecessary only for self-priming arrangements or when suction is already flooded.

Pump total head represents the net energy added to the fluid per unit weight, expressed as an equivalent height of fluid. It accounts for elevation, pressure, velocity and system losses—not the pump's physical height.

Centrifugal pumps are most commonly used in building booster systems because they provide smooth continuous flow, are available in multistage high-head configurations and work well with variable-speed pressure control.

Protective earthing provides a low-impedance path for fault current and stabilizes exposed conductive parts/neutral references. Earth resistance should be low enough to meet protection requirements and is checked periodically because soil/moisture/corrosion can change electrode performance. Key relation: Touch voltage and disconnection time depend on earthing and protective-device coordination.

Exam focus: Low earth resistance is desirable—not high resistance. Common trap: Never state that high earth resistance improves safety.

A diesel generator set in a commercial building primarily provides backup/standby electrical power when the normal utility/grid supply fails. An automatic transfer system can start the DG and transfer selected essential loads.

Fire pumps and fire alarm systems are life-safety loads and must remain available during loss of normal power, so they are connected to emergency/standby power arrangements as required by building fire-safety design. General office loads and decorative lighting are not comparable essential loads.

Atomic hydrogen welding strikes an arc between two non-consumable tungsten electrodes in hydrogen. H₂ splits in the arc and recombines at the workpiece, releasing intense heat.

Seam-welding wheel electrodes must carry very high current, remove heat quickly and resist wear, so copper-based alloys are used.

A VAV system primarily varies the quantity of supply air delivered to each zone according to its thermal demand while the central supply-air temperature is usually maintained within a controlled range. VAV boxes modulate airflow using dampers/controls.

The condenser removes heat from the high-pressure refrigerant and rejects it to outdoor air or cooling water. During this process refrigerant changes from high-pressure vapor toward liquid before entering the expansion device.

Busbar trunking distributes high current through enclosed rigid bus conductors and is widely used for vertical risers in high-rise buildings. Plug-in/tap-off units make load additions and reconfiguration easier than replacing large cable runs. Key relation: ΔV depends on I(R cosφ + X sinφ) and run length.

Exam focus: Tap-off flexibility is a key BBT advantage. Common trap: Do not assume busbar trunking always has higher voltage drop.

The 100 kg charge is 0.1 ton, so the steel needs 0.1 × 1500 = 150 kWh of useful melting energy. At 60% efficiency, the electrical input must be 150 / 0.60 = 250 kWh.