- 1. Introduction
- SpecX quick selector
- 2. HVAC System Classifications
- 3. HVAC System Components
- 4. Design Parameters & Performance Standards
- 5. Ducting & Air Distribution
- Duct Materials
- Insulation Materials
- 6. Common HVAC System Types (Configuration‑wise)
- 7. Codes & Standards
- 8. Site QA/QC Guidelines
- Pre‑Installation
- During Installation
- Post Installation
- 9. Common Failures & Troubleshooting
- 10. Testing & Commissioning
- 11. BOQ Sample Items
- 12. HVAC Performance Checklist (Summary)
- 13. Consultant Focus Points
1. Introduction
Heating, Ventilation, and Air Conditioning (HVAC) systems regulate indoor temperature, humidity, air purity, and comfort.
They directly influence occupant health, energy efficiency, and building sustainability.
A well-designed HVAC system ensures:
- Indoor air quality within ASHRAE 62.1 limits
- Thermal comfort per ASHRAE 55
- Energy performance as per ECBC 2017 / ASHRAE 90.1
In commercial buildings, HVAC energy consumption accounts for 40–60% of total energy use, making design optimization essential.
SpecX quick selector
- Offices: Chilled water system with AHUs + VAVs; target chiller COP ≥ 4.0; supply air 12–14 °C; duct leakage ≤ 5%
- Mid‑scale: VRV/VRF with heat recovery; MERV 8–11 filters; condensate traps and insulated drains
- Small rooms: High‑wall split with fresh air via treated air (FAHU) or ERV; slope drain pans 1:100
- Ducting: GI 24–26 SWG with 25–50 mm insulation; sealing with mastic/tape to SMACNA
2. HVAC System Classifications
System Type | Description | Typical Use Case |
Window / Split AC | Independent DX units | Small rooms, retail, residential |
VRV / VRF | Multi-split system with variable refrigerant flow | Office, hotels, hospitals |
Packaged / Ducted AC | Centralized packaged DX units | Auditoriums, malls |
Chilled Water Systems | Water-cooled/air-cooled chillers with AHUs & FCUs | Large buildings |
Evaporative / Cooling Tower | Air cooling via evaporation | Industrial workshops |
Hybrid / Geothermal | Heat pump-based sustainable systems | Green buildings |
3. HVAC System Components
Category | Component | Purpose |
Cooling Generation | Chillers (air/water-cooled), compressors | Heat removal |
Air Handling | AHU, FCU, filters, coils | Temperature & IAQ control |
Air Distribution | Ducting, diffusers, grilles | Uniform air supply |
Water Circulation | Pumps, valves, cooling towers | Chilled water loop |
Controls | Thermostats, actuators, dampers, sensors | Automation & efficiency |
Insulation | Nitrile rubber, fiberglass, PU foam | Condensation prevention |
Filtration | Pre-filter, fine filter, HEPA | IAQ & cleanliness |
4. Design Parameters & Performance Standards
Parameter | Typical Value / Limit | Reference Standard |
Room temperature | 22–26°C | ASHRAE 55 |
Relative humidity | 40–60% | ISHRAE / NBC |
Air Changes per Hour (ACH) | 6–12 (offices), 15+ (labs) | NBC Part 8 |
Chiller COP | ≥ 4.0 (water-cooled), ≥ 3.0 (air-cooled) | ASHRAE 90.1 |
Filter efficiency | MERV 8–13 / HEPA 99.97% | ASHRAE 52.2 |
Duct leakage | ≤ 5% | SMACNA |
Noise level | ≤ 45 dB(A) (office) | ISHRAE Handbook |
5. Ducting & Air Distribution
Duct Materials
- Galvanized Iron (GI) — 22–26 gauge
- Aluminum — lightweight, corrosion resistant
- Fabric / PVC ducts — temporary or industrial use
Insulation Materials
Type | Application | Thickness |
Nitrile Rubber | AHUs, chilled water lines | 19–25 mm |
Glass Wool | Supply/return ducts | 25–50 mm |
PU Foam | External ducts, chillers | 25–40 mm |
All duct fabrication must comply with SMACNA and DW144 standards.
Proper insulation is essential to prevent condensation and maintain energy efficiency.
6. Common HVAC System Types (Configuration‑wise)
System | Medium | Control Type | Advantages |
DX (Direct Expansion) | Refrigerant | Thermostat | Compact, low initial cost |
Chilled Water | Water | BMS/PLC | Scalable, high efficiency |
VRF/VRV | Refrigerant | Inverter-driven | Zonal control, efficient |
Radiant Cooling | Water | Thermostatic valves | Silent, high comfort |
Hybrid (Solar/Heat Pump) | Mixed | Smart BMS | Energy savings, sustainable |
7. Codes & Standards
Standard / Code | Scope |
ISHRAE Handbook | Design parameters & HVAC practice |
ASHRAE 55 | Thermal comfort standard |
ASHRAE 62.1 | Ventilation for acceptable IAQ |
ASHRAE 90.1 | Energy standard for buildings |
SMACNA / DW144 | Duct construction standards |
NBC 2016 Part 8 | HVAC & mechanical systems |
ECBC 2017 | Energy conservation & efficiency |
8. Site QA/QC Guidelines
Pre‑Installation
☑️ Verify approved shop drawings and GFCs
☑️ Check duct routing & clearance (avoid clashes)
☑️ Confirm insulation material & density
☑️ Approve filter grades and chiller capacity
During Installation
☑️ Ensure proper slope in drain pans
☑️ Duct joints sealed with aluminum tape or mastic
☑️ Valves, gauges, and dampers as per approved drawings
☑️ Verify insulation continuity and cladding integrity
Post Installation
☑️ Pressure test ducts and chilled water lines
☑️ Balance airflow via TAB (Testing, Adjusting, Balancing)
☑️ Record chiller efficiency (COP/EER)
☑️ Log AHU noise & vibration test readings
9. Common Failures & Troubleshooting
- Condensation on ducts → poor insulation / air leaks; seal joints and increase insulation
- Uneven cooling → poor damper balancing; perform TAB
- Low chiller efficiency → fouled condenser tubes; clean periodically
- High noise levels → fan imbalance/duct resonance; re‑balance, add acoustic lining
- Mold/odor → clogged filters/pans; maintain filters, disinfect coils
Problem | Root Cause | Remedy / Preventive Action |
Low suction pressure | Refrigerant leakage | Check connections, recharge system |
10. Testing & Commissioning
Key Tests:
- Duct leakage test (pressure decay method)
- Chilled water hydrostatic test
- Airflow & CFM measurement
- Noise & vibration level test
- COP / EER verification
- AHU performance test
- Condensate drain test
Documentation:
- Test reports
- Calibration certificates
- As-built drawings
- O&M manual with maintenance schedule
11. BOQ Sample Items
Item No. | Description | Unit |
1 | Supply & installation of 25 TR air-cooled chiller with pump set, interconnecting piping, insulation, testing & commissioning complete | Nos |
2 | GI ducting of 24 SWG with 25 mm glass wool insulation, cladding, supports, and balancing | Sq.m |
3 | Supply & installation of AHU 6000 CFM, 3-row chilled water coil with filters, dampers, controls, and commissioning | Nos |
4 | Chilled water piping in MS ‘C’ class, 50 mm dia with 19 mm nitrile insulation | Rm |
12. HVAC Performance Checklist (Summary)
Parameter | Expected Value | Checked By | Remarks |
Indoor temperature | 22–26°C | Site engineer | |
RH level | 40–60% | Site engineer | |
Duct leakage | ≤ 5% | QA team | |
Chiller COP | ≥ 4.0 | MEP head | |
Noise level | ≤ 45 dB(A) | QA | |
Filter class | As per design | QA | |
Pressure test results | Pass | QA |
13. Consultant Focus Points
- Energy modeling to meet ECBC 2017 targets
- Material submittals: chiller data, filter grades, duct thickness
- Shop drawings to include airflow & static pressure
- Duct supports spacing as per SMACNA tables
- Drainage slope 1:100 min for AHU pans
- Annual maintenance contracts must include TAB verification