Building Services (CE-703 (D)) - Unit 5 Short Notes

UNIT 5: Building Services

I. Building Regulations and Standards

National Building Code (NBC) of India

• Scope: Provides comprehensive guidelines for building construction, safety, and services across India. Covers planning, design, construction, and maintenance aspects.

• Importance: Ensures uniformity, safety, and sustainability. Serves as a reference for local building byelaws and IS codes. Mandates minimum standards for structural safety, fire safety, and building services.

Classification of Buildings (NBC)

Buildings are classified based on occupancy and height/area.

Exam Tip: Classification directly dictates fire safety requirements (e.g., compartment size, travel distance, number of exits). High-rise buildings (height > 15m or 4 storeys) have stricter norms.

II. Vertical Transportation Systems

A. Lifts

Classification:

• Passenger Lifts: For carrying people.

• Freight/Goods Lifts: For cargo, no passenger accompaniment.

• Hospital Lifts: Larger size, emergency controls, smooth ride.

• Service Lifts/Dumbwaiters: Small goods/service.

• Residential Lifts: Compact, often hydraulic.

• High-Speed Lifts: For skyscrapers (> 2.5 m/s).

Types of Lift Operation:

• Collective Control: Buttons for all floors inside car & hall. Responds in sequence.

• Selective Collective: Up/down hall buttons separate. More efficient for mid-rise.

• Two-Way Selective Collective: Separate up/down hall buttons + car buttons. Most efficient for high traffic.

• Automatic Operation: Microprocessor-based, no attendant.

Lift Control Systems:

1. Relay-Based: Older, electromechanical relays.

2. Microprocessor-Based: Modern, flexible, handles complex traffic.

3. Group Control: Manages multiple lifts as a single system to optimize response (e.g., "destination control" systems).

Traffic Analysis & Requirement Calculation:

Key parameters:

• Population (P): Number of people in the building/zone.

• RTT (Round Trip Time): Time for one complete trip (up/down).

• Interval (Int): Average waiting time for passengers. Int = RTT / N (N = number of lifts).

• Capacity (Q): Rated load (kg) or persons.

Standard Formula for Number of Lifts (N):

$$ N = \frac{P \times \text{Peak Period Factor} \times \text{Interval Target}}{5 \times \text{Car Capacity (persons)}} $$

Common Pitfall: Interval is the target average waiting time, not RTT. Use standard tables (e.g., from NBC/IS 14665) for peak factors (typically 10-15 min for offices).

Safety Precautions & Codes:

• IS Codes: IS 14665 (Electric lifts), IS 15259 (Hydraulic lifts).

• Safety Gears: Speed governors, safety clutches (grab rails).

• Buffers: Spring/oil/hydraulic at pit bottom.

• Other: Over-speed governor, emergency alarm, light/fan in car, pit access.

Fire Safety Provisions in Lifts:

• Lift Lobby: Separate, enclosed with fire-rated doors.

• Pressurization: Lobby & car pressurised to prevent smoke ingress.

• Recall: Phase-I (all cars return to ground floor & park open) & Phase-II (fireman's operation).

• Fireman's Switch: Located in lobby, overrides normal control.

• Non-Combustible Materials: Car interior, wiring.

B. Escalators and Travelators

Escalator Working Mechanism:

• Steps: Rigid, interlinked, form moving staircase.

• Drive: Motor (usually gearless) drives step chain via sprocket.

• Handrails: Synchronized with steps for balance.

• Truss: Supporting structure housing machinery.

Design Considerations:

• Inclination: Typically 30° (max 35°).

• Speed: 0.5 m/s (typical), up to 0.75 m/s.

• Capacity: Depends on step width (600mm, 800mm, 1000mm) & speed.

• Length: Determined by vertical rise & angle.

Differences: Lifts vs. Escalators

Travelators (Moving Walkways):

• Application: Airports, supermarkets, long corridors.

• Design: Flat or slightly inclined (≤ 10°). Pallet or belt type.

• Speed: 0.5-0.75 m/s.

III. Fire Safety Engineering

A. Fire Fundamentals

Modes/Classification (IS 1646):

• Class A: Ordinary combustibles (wood, cloth, paper).

• Class B: Flammable liquids/gases (petrol, LPG).

• Class C: Electrical fires (live equipment).

• Class D: Combustible metals (Na, K, Mg).

• Class E: High voltage fires (specialized).

• Class F: Cooking oils/fats (kitchen fires).

Common Causes in Buildings:

• Electrical short circuits

• Cooking/kitchen fires

• Smoking materials

• Heating equipment

• Open flames

• Arson

B. Fire Protection Systems

Fire Hydrants:

• Types: External (yard hydrant), Internal (within building).

• Provisions:

  • Hose Cabinets: 2 x 15m hoses, branch pipe, nozzle.

  • Hydrant Valves: Riser mains (2" dia), landing valves at each floor.

  • Pump & Pressure: Jockey pump (maintain pressure), main pump (fire flow).

  • Water Source: Underground tank (100,000L min for high-rise), borewell, municipal.

  • Layout: Max 30m from any point, two independent risers.

Fire Fighting Systems:

1. Carbon Dioxide (CO₂): For electrical/flammable liquid fires. Stored as liquid, discharges as gas. No residue, asphyxiation risk.

2. Sprinklers: Automatic, heat-sensitive. Types: Wet pipe (standard), Dry pipe (freezing), Deluge (high hazard). Design density: 4.1-20.4 L/min/m².

3. Foam Systems: For Class B fires. AFFF (Aqueous Film Forming Foam) forms blanket.

4. Fire Extinguishers: ABC powder, CO₂, water, foam.

Fire Escapes:

• Design: External staircases or internal fire-rated staircases.

• Requirements (NBC):

  • Width ≥ 1.2m (residential), 1.5m (others).

  • Number based on occupant load & travel distance.

  • Enclosed with 2h fire rating.

  • Pressurized in high-rises.

  • Materials: Non-combustible (concrete, steel with fireproofing).

Service Ducts & Escape Routes:

• Planning: Ducts (electrical, plumbing, HVAC) should not penetrate fire walls/compartment walls. If unavoidable, fire-stopping required.

• Escape Route: Protected corridor/stair with fire-resistant construction. No accumulation of combustibles. Clear signage & emergency lighting.

Fire Safety for High-Rise Buildings:

• Compartmentalization: Firewalls, fire doors.

• Pressurization: Staircases & lift lobbies positively pressurised.

• Smoke Management: Smoke vents, pressurised lobbies.

• Fire Lift: Dedicated lift with fireman's switch, 2h rating, separate shaft.

• Control Room: 24/7 manned with fire alarm panel.

IV. HVAC Systems

A. Ventilation

• Natural Ventilation: Wind-driven & buoyancy-driven (stack effect). Requires openings on opposite walls.

• Mechanical Ventilation: Fans & ducts. Types: Supply, Exhaust, Dilution.

• Hybrid: Combination (e.g., supply fan + natural exhaust).

• Essentials:

  • Air Changes per Hour (ACH): Depends on occupancy/activity (e.g., 2-4 for offices, 15-20 for kitchens).

  • Indoor Air Quality (IAQ): Control of pollutants (CO₂, VOCs, particulates). ASHRAE Standard 62.1.

B. Air Conditioning

• Unitary Systems: Self-contained package (window, split, packaged rooftop). Single factory-assembled unit.

• Central Systems: Central plant (chiller/boiler) with air/water distribution to multiple zones.

• Types:

  1. Window AC: Single unit, for small rooms.

  2. Split AC: Indoor fan coil + outdoor compressor. Ductless.

  3. Packaged AC: All components in one cabinet, ducted to spaces.

  4. Central Plant: Chiller + AHUs (Air Handling Units) + ducts. For large buildings.

C. Thermal Insulation

• Methods:

  • Material Insulation: Bulk (glass wool, rock wool, EPS), reflective (aluminium foil).

  • Cavity Wall: Air gap in wall reduces heat transfer.

  • Exterior Insulation: ETICS (External Thermal Insulation Composite System).

• Thermal Insulation of Walls:

  • Materials: Brick (autoclaved aerated), concrete blocks, insulation boards.

  • U-value (W/m²K): Measure of heat transfer. Lower = better insulation. NBC prescribes max U-values for different climates.

  • Placement: Exterior > Interior > Cavity. Exterior most effective (thermal mass protected).

V. Water Supply and Plumbing Systems

A. Water Supply

• Systems for Multistoried Buildings:

  1. Direct System: Mains pressure sufficient. Simple, no tanks.

  2. Indirect System: Overhead tanks (sumps) at each floor/zone. Gravity feed.

  3. Booster Pump System: Underground tank + pumps (variable speed) to maintain pressure in upper floors.

• Pipe Materials:

  • GI (Galvanized Iron): Traditional, durable, prone to corrosion.

  • PVC/UPVC: Lightweight, corrosion-resistant, for cold water.

  • HDPE: Flexible, jointless, for buried mains.

  • CPVC: For hot & cold water, higher temperature rating.

  • PEX: Flexible, for internal distribution.

• Fixtures & Appliances: Taps, showers, WCs, urinals, sinks. Requirements: Adequate flow rate, anti-siphonage, accessibility (as per NBC).

B. Swimming Pool Systems

• DBP (Disinfection By-Products) Mitigation:

  • Use alternative disinfectants (e.g., chlorine dioxide, ozonation, UV).

  • Maintain optimal pH (7.2-7.8) & ORP (Oxidation-Reduction Potential).

  • Adequate dilution (fresh water addition).

  • Advanced Oxidation Processes (AOPs): Ozone + UV.

• Algae Control:

  • Chemical: Algaecides (copper-based, quaternary ammonium), maintain chlorine residual.

  • Physical: Proper filtration (sand/DE), brushing walls, vacuuming, UV treatment.

VI. Acoustics and Noise Control

A. Noise Fundamentals

• Sources:

  • External: Traffic, aircraft, industry.

  • Internal: Speech, equipment (HVAC, lifts), footfall.

  • Services: Pumps, fans, plumbing, duct-borne noise.

• Planning Stage Control:

  • Site layout: Place noisy areas (parking, plant) away from quiet zones (bedrooms, auditoriums).

  • Building orientation: Shield facades from main noise source.

  • Zoning: Separate noisy & quiet functions.

• Noise Rating (NR) Curves:

  • Graph of permissible octave band sound pressure levels vs. frequency.

  • Application: Specify acceptable background noise levels for different spaces (e.g., NR 25 for libraries, NR 40 for offices). Design HVAC systems to meet target NR curve.

B. Sound Insulation

• Sound Insulation of Walls (Airborne): Governed by Mass Law: R (dB) ∝ 20 log(M), where M = surface density (kg/m²). Increase mass → higher insulation.

  • Stiffness: Stiff partitions have coincidence dip (low insulation at certain freq).

  • Damping: Use constrained layer damping (viscoelastic material).

  • Construction: Cavity walls, double leaf with absorbent in cavity, resilient mounts.

• Reverberation Time (RT):

  • Definition: Time for sound to decay by 60 dB after source stops.

  • Sabine Formula (for diffuse field):

$$ RT_{60} = \frac{0.161 \times V}{A} = \frac{0.161 \times V}{\sum (S_i \times \alpha_i)} $$

    Where: `V` = Volume (m³), `A` = Total absorption (sabins), `S_i` = Area of surface i, `α_i` = absorption coefficient.

*   **Design:** Optimize for speech clarity (shorter RT) or music richness (longer RT). Auditoriums: 1.0-1.8 sec.

• Materials for Good Acoustics:

  • Absorbers: Porous (fiberglass, foam), resonant (perforated panels), membrane.

  • Reflectors: Hard, smooth surfaces (concrete, wood) for early reflections.

C. Acoustic Design of Auditoriums

• Factors:

  1. Shape: Shoebox (good for music), fan-shaped (good for speech). Avoid concave surfaces (focusing).

  2. Materials: Combination of reflective (front, ceiling) & absorptive (rear, balcony undersides).

  3. Seating: Upholstered seats absorb sound when occupied.

  4. Volume & RT: Match RT to program.

  5. Balcony Design: Avoid deep overhangs causing shadows.

  6. Diffusers: Scatter sound to avoid echoes & dead spots.

• Open-Air Theatre:

  • Stage: Roof or canopy for projection & protection.

  • Seating: Sloped, absorbent material.

  • Back Wall: Highly absorptive or diffusive to prevent echoes.

  • Natural Vegetation: Can act as sound barrier/absorber.

VII. Sustainable Building Services

A. Green Building Concepts

• Concerns & Principles:

  • Energy Efficiency: Reduce operational energy (HVAC, lighting).

  • Water Conservation: Reduce, reuse, recycle.

  • Material Efficiency: Sustainable sourcing, recycled content, local.

  • Indoor Environmental Quality (IEQ): Ventilation, low-VOC materials, daylight.

  • Site Sustainability: Reduce ecological footprint, manage stormwater.

• Sustainable Site Planning: Minimize disturbance, preserve vegetation, manage runoff, reduce light pollution.

B. Resource Management

• Rainwater Harvesting (RWH):

  • System: Catchment (roof) → Conduits → First Flush (diverts dirty water) → Filter (sand, charcoal) → Storage (tank) → Utilization (flushing, landscaping) or Recharge (borewell/well).

  • Design: Storage capacity = (Rainfall × Catchment area × Runoff coefficient) - (Consumption).

• Landscaping & Horticulture:

  • Benefits: Reduces heat island, improves air quality, stormwater management, psychological well-being.

  • Selection: Native/drought-resistant species, shade trees (reduce cooling load).

  • Irrigation: Drip/sprinkler, use treated wastewater/RWH.

• Solar Energy Systems:

  • Solar Water Heating (SWH): Flat plate or evacuated tube collectors → storage tank → distribution. Efficiency ≈ 40-60%.

  • Photovoltaic (PV) Systems:

    • Grid-Tied: Connected to utility, net metering.

    • Stand-Alone: With battery backup.

    • Sizing: PV Capacity (kWp) = (Daily Load kWh) / (Peak Sun Hours × System Efficiency).

  • Sketches Required: Show SWH loop (collector-tank-pipes) and PV layout (panels-inverter-battery-grid).

VIII. Building Planning and Service Integration

A. Parking and Transportation

• Design of Car Parking Systems:

  • Layout: Perpendicular (most efficient), angled (45°-60°), parallel.

  • Dimensions: Standard bay 2.4m x 4.8m (compact), 2.6m x 5.5m (regular). Aisle width depends on angle.

  • Mechanical Systems: For high-density (e.g., rotary, puzzle, lift-type).

  • Multi-Level: Ramps (max slope 1:6) or lifts.

    DiagramSEARCH: car parking layout dimensions

B. Waste Management

• Refuse Collection Systems:

  • Chutes: For high-rise, from each floor to central collection room. Fire-rated, with inlet doors & cleaning provision.

  • Storage: Dedicated, ventilated room near service entrance. Bins for segregation (wet/dry).

  • Collection: Frequency, vehicle access, compactor for large complexes.

C. Security and Access

• Access Control Systems:

  1. Biometric: Fingerprint, iris (high security).

  2. Card-Based: Proximity (RFID), smart card.

  3. Keypad: PIN code.

  4. Intercom: Audio/video for visitor screening.

  • Integration: Often part of Building Management System (BMS).

D. Service Coordination

• Integration in Design:

  • Common Shafts/Ducts: For vertical routing (toilets, risers).

  • Coordination Drawings: Overlay of all services (structural, MEP) to avoid clashes.

  • Clearances: Maintain minimum distances between services (e.g., electrical & plumbing).

  • Access Panels: For maintenance in concealed areas.

IX. Supervisory and Administrative Aspects

• Administrative Functions of Supervisors:

  • Planning & Scheduling: Work breakdown, resource allocation (manpower, material, equipment).

  • Coordination: Between trades (civil, electrical, plumbing), client, architect.

  • Quality Control: Inspections, compliance with specifications & codes.

  • Safety Management: Site safety audits, PPE enforcement, incident reporting.

  • Documentation: Progress reports, site diaries, measurement books.

  • Cost Control: Monitoring expenditure, variation orders.

• Safety Precautions in Lift Installation & Maintenance:

  • Site Safety: Barricading hoistway, lockout/tagout for power, fall protection in shaft.

  • Testing: Pre-commissioning tests (safety gear, buffers, emergency operations) by authorized personnel.

  • Codes: Strict adherence to IS 14665 during installation & periodic maintenance.

  • Training: Only trained technicians to operate/test equipment.