How To Do A Heat Load Calculation

Heat Load Formula:

\[ \text{Heat Load} = \sum (U \times A \times \Delta T + \text{Internal Gains} + \text{Infiltration}) \]

U Value (W/m²K):

W/m²K

Area (A):

m²

Temperature Difference (ΔT):

Internal Gains:

Infiltration:

Heat Load:

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1. What Is Heat Load Calculation?

Heat load calculation is a fundamental engineering process used to determine the amount of heating or cooling required to maintain comfortable conditions in a building. It accounts for heat transfer through building envelopes, internal heat gains, and infiltration losses.

2. How Does The Calculator Work?

The calculator uses the comprehensive heat load formula:

\[ \text{Heat Load} = \sum (U \times A \times \Delta T + \text{Internal Gains} + \text{Infiltration}) \]

Where:

\( U \) — Thermal transmittance coefficient (W/m²K)
\( A \) — Surface area (m²)
\( \Delta T \) — Temperature difference between inside and outside (K)
\( \text{Internal Gains} \) — Heat generated internally by occupants, equipment, and lighting (W)
\( \text{Infiltration} \) — Heat loss due to air leakage (W)

Explanation: The equation calculates total heat loss by summing conductive heat transfer through building surfaces and additional heat components from internal sources and air infiltration.

3. Importance Of Heat Load Calculation

Details: Accurate heat load calculation is essential for proper HVAC system sizing, energy efficiency optimization, thermal comfort assurance, and compliance with building codes and standards.

4. Using The Calculator

Tips: Enter U-value in W/m²K, area in square meters, temperature difference in Kelvin, internal gains in watts, and infiltration in watts. All values must be positive numbers for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is U-value in heat transfer?
A: U-value measures the rate of heat transfer through a building component. Lower U-values indicate better insulation and reduced heat loss.

Q2: How is temperature difference (ΔT) determined?
A: ΔT is the difference between desired indoor temperature and design outdoor temperature for the specific climate zone and season.

Q3: What are typical internal gains in buildings?
A: Internal gains include heat from occupants (100W/person), lighting, computers, appliances, and other electrical equipment operating in the space.

Q4: How is infiltration calculated?
A: Infiltration is calculated based on air changes per hour, building volume, and temperature difference, representing heat loss through unintentional air leakage.

Q5: Why convert to BTU/h?
A: BTU/h (British Thermal Units per hour) is commonly used in HVAC industry, especially in North America, making results more accessible to professionals.