Table of Contents
- 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
- Disclaimer
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
Disclaimer
Conix is an industry initiative & a neutral resource, compiled from industry references and best practices. It is not brand-specific. Always cross-check with project requirements and local codes before finalizing specifications.