Fire Protection Plumbing Quick Reference Guide

1. Cooling Load Components

Sensible Heat (temperature-related)
Latent Heat (humidity-related)

Main Sources of Heat Gain:

Source	Examples
External Loads	Sunlight, outdoor air temperature
Internal Loads	People, lights, appliances
Infiltration/Ventilation	Air leaks, fresh air intake

2. Required Data for Calculation

Building Dimensions (Length, width, ceiling height)
Wall/Roof Materials (U-value, insulation)
Window Types & Shading (Glass type, curtains)
Occupancy (Number of people, activity level)
Lighting & Equipment (Wattage, usage hours)
Outdoor Design Conditions (Sri Lanka: ~32–35°C DB, ~70–80% RH)
Indoor Design Conditions (Comfort: 24–26°C, 50–60% RH)

3. Calculation Methods

A. Manual Calculation (ASHRAE CLTD/CLF Method)

Conductive Heat Gain: Q = A × U × ΔT

Where: A = Area (m²), U = Heat transfer coefficient (W/m²K), ΔT = Temperature difference

Solar Heat Gain: Q = A × SHGC × SC × CLF

Internal Loads (People): Q = No. of People × Heat Gain (W/person)

B. Software-Based Calculation

HAP (Hourly Analysis Program)
Carrier E20-II
IES VE
CoolCalc / HVAC-Calc

4. Standards to Follow

International Standards:

ASHRAE Handbook - Fundamentals
ASHRAE Standard 55 (Thermal comfort)
ASHRAE Standard 62.1 (Ventilation)
ISO 7730 (Thermal comfort)

Sri Lankan Standards (SLS):

SLS 1246 (Energy performance of buildings)
SLS 530 (Electrical installations)
SLS 1553 (AC & refrigeration safety)

5. Sri Lanka-Specific Considerations

            High Humidity → Prioritize dehumidification
Frequent Power Cuts → Use inverter ACs
Monsoon Season → Account for extra moisture load
Follow National Ozone Unit (NOU) refrigerant regulations

        

6. Example Calculation (Small Office)

Load Type	Calculation	Heat Gain (W)
Wall Heat Gain	20m² × 2.5 W/m²K × (34°C-25°C)	450 W
Window Solar	10m² × 0.5 SHGC × 200 W/m²	1000 W
People (5)	5 × 70 W (sensible) + 5 × 60 W	650 W
Total Load	Sum of all	≈1.1 TR

Add 15% safety factor → ~1.3 Tons Refrigeration (TR) Required

HVAC Cooling Load Analysis Reference Guide