Final Report of project HVAC Design for a 3BHK Residential House

 

 Detailed explanation of the Final Project for designing a complete HVAC system, covering both a 3BHK house (residential) and a small office (commercial). This includes load calculation, equipment selection, duct layout, IAQ (Indoor Air Quality) considerations, and design steps.

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🏠 A. HVAC Design for a 3BHK Residential House

🔹 1. Basic Assumptions:

Room	Size (in ft)	Occupants	Orientation	Windows
Bedroom 1	12 × 12 × 10	2	West	1
Bedroom 2	12 × 14 × 10	2	South	1
Bedroom 3	10 × 12 × 10	1	North	1
Living Room	14 × 16 × 10	4	East	2
Kitchen	10 × 10 × 10	1	East	1

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🔹 2. Load Calculation

Use Manual J method for residential load:

✅ Formula:

Cooling Load (BTU/hr) ≈ Area × 30–40 BTU/hr (typical)

Rough Estimate:

 (People, Lights, Appliances): ~3,000 BTU/hr

👉 Total Cooling Load ≈ 30,000 BTU/hr
(= 2.5 Tons)

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🔹 3. Equipment Selection

Room Type	Equipment
Bedrooms	1 Ton Split AC each
Living + Dining	1.5 Ton Split AC
Kitchen	Exhaust fan, cross-ventilation

Total Units:

• 3 × 1 Ton + 1.5 Ton = 4.5 Tons of Cooling

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🔹 4. Duct Design Layout (Optional - for Central AC)

For ducted AC system (instead of splits):

Use flexible ducts or rectangular sheet metal ducts.

Maintain air velocity = 700–900 FPM.
Use supply diffusers in the center of rooms, returns at wall level.

Basic layout:

    [Bedroom 1]      [Bedroom 2]
         |               |
      [ Duct ]-------[Living Room]----[Bedroom 3]
         |
     [ AHU/Furnace ]
         |
     [Outdoor Condenser]

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🔹 5. IAQ Considerations

Fresh Air Inlet: Small fresh air duct with filter.

Exhaust Fan: In kitchen and bathroom.
Air Filters: MERV 8–11 filters.
Humidity Control: Use of dehumidifier in monsoon season.

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🏢 B. HVAC Design for a Small Office (Commercial)

🔹 1. Assumptions

Area	Size (ft²)	Occupants	Equipment (W)
Reception	150	2	300
Work Area	600	6	1500
Cabin	150	1	300
Conference	200	6	1000

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🔹 2. Load Calculation (Use Manual N for commercial)

Components:

Area Load: Total 1100 ft² × 35 BTU/hr = 38,500 BTU/hr

People Load: 15 people × 400 BTU/hr = 6,000 BTU/hr
Equipment Load: ~3000 BTU/hr
Lighting Load: 1100 ft² × 3 W/ft² × 3.41 = ~11,000 BTU/hr

👉 Total ≈ 58,500 BTU/hr ≈ 4.9 Tons ≈ 5 Ton AC needed

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🔹 3. Equipment Selection

Central Ducted Package Unit or VRF/VRV System

Zone	Suggested Unit
Work Area	2 Ton cassette type
Conference Room	1.5 Ton wall mount
Reception/Cabin	1.5 Ton combined

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🔹 4. Duct Design Layout

Use ducted central unit with VAVs for zoning.

Air velocity = 1000–1200 FPM for commercial ducts.
Duct material: GI sheet metal.

Example Layout:

[AHU/Package Unit]
      |
  [Main Duct]
 /     |     \
Rec  Work  Conf

Supply Vents: Each room

Return Air Duct: Common return to AHU
Fresh Air Intake: Through treated fresh air (TFA) unit

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🔹 5. IAQ Considerations

CO₂ Sensors for occupancy-based ventilation

HEPA or MERV 13 filters
UV Lights in ducts to kill microbes
Fresh Air Ventilation: 15–20 CFM/person
Humidity Control: Maintain RH 40–60%

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📐 Summary of Design Parameters

Parameter	Residential (3BHK)	Small Office
Cooling Load	2.5 Tons	5 Tons
Equipment Type	Split / Central	VRF / Ducted
Air Flow Rate	400 CFM/ton	400 CFM/ton
Air Changes	4–6 per hour	6–10 per hour
Fresh Air Required	Basic Ventilation	TFA system
Filtration	MERV 8–11	MERV 13+

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🛠 Final Deliverables

✅ 1. Load Calculation Sheet
✅ 2. Equipment List with Specs
✅ 3. Duct Layout Diagram
✅ 4. IAQ Measures Plan
✅ 5. Energy Efficiency Notes (e.g., inverter AC, insulation, zoning)