1. What is a Heat Loss Calculator?

Definition: This calculator estimates the rate of heat transfer through a building element or surface using the basic heat loss equation.

Purpose: It helps engineers, architects, and energy assessors determine heat flow through building envelopes for HVAC sizing and energy efficiency analysis.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Heat loss rate (Watts)
• \( U \) — U-value (W/m²K)
• \( A \) — Surface area (m²)
• \( \Delta T \) — Temperature difference across surface (Kelvin)

Explanation: The U-value represents thermal transmittance, area is the surface size, and ΔT is the temperature gradient driving heat flow.

3. Importance of Heat Loss Calculation

Details: Accurate heat loss calculations are essential for proper HVAC system sizing, energy efficiency assessments, and building code compliance.

4. Using the Calculator

Tips: Enter the U-value (thermal transmittance) in W/m²K, surface area in m², and temperature difference in Kelvin. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What are typical U-values?
A: Single-glazed window ≈ 5.7, double-glazed ≈ 2.8, brick wall ≈ 2.0, well-insulated wall ≈ 0.3 W/m²K.

Q2: How do I calculate ΔT?
A: Subtract outdoor temperature from indoor temperature (both in °C or K - the difference is the same).

Q3: Does this account for air infiltration?
A: No, this calculates conductive heat loss only. Ventilation losses require additional calculations.

Q4: What if my area is in ft²?
A: Convert to m² by dividing ft² by 10.764 before entering.

Q5: How accurate is this calculation?
A: This provides basic conductive heat loss. For comprehensive analysis, consider thermal bridging, orientation, and other factors.