Room by Room Heat Loss Calculator

Heat Loss Formula:

\[ Q_{room} = U \times A \times \Delta T + 0.33 \times V \times ACH \times \Delta T \]

U-value (W/m²K):

Surface Area (m²):

Temperature Difference (ΔT in K):

Room Volume (m³):

Air Changes per Hour (ACH):

Fabric Heat Loss (W):

Ventilation Heat Loss (W):

Total Heat Loss (W):

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1. What is a Room by Room Heat Loss Calculator?

Definition: This calculator estimates the heat loss for individual rooms based on building fabric properties and ventilation rates.

Purpose: It helps architects, engineers, and homeowners determine heating requirements for specific spaces in a building.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ Q_{room} = U \times A \times \Delta T + 0.33 \times V \times ACH \times \Delta T \]

Where:

\( Q_{room} \) — Total heat loss (Watts)
\( U \) — U-value of building elements (W/m²K)
\( A \) — Surface area of building elements (m²)
\( \Delta T \) — Temperature difference between inside and outside (Kelvin)
\( V \) — Room volume (m³)
\( ACH \) — Air changes per hour (1/h)

Explanation: The calculation considers both heat loss through building fabric (walls, windows, etc.) and heat loss due to ventilation.

3. Importance of Heat Loss Calculation

Details: Accurate heat loss calculations ensure proper sizing of heating systems, energy efficiency, and occupant comfort.

4. Using the Calculator

Tips: Enter the U-value of your building elements, surface area, temperature difference, room volume, and air changes per hour (default 0.5 ACH for typical rooms).

5. Frequently Asked Questions (FAQ)

Q1: What is a typical U-value?
A: Modern walls: 0.2-0.3 W/m²K, Windows: 1.0-2.0 W/m²K, Older buildings may have higher values.

Q2: How do I determine ACH?
A: 0.5 for normal rooms, 1.0 for leaky buildings, 0.3 for very tight construction.

Q3: What temperature difference should I use?
A: Difference between desired indoor temp and design outdoor temp (e.g., 20°C inside and -5°C outside = 25K ΔT).

Q4: Why is the ventilation factor 0.33?
A: It's the product of air density (1.2 kg/m³) and specific heat capacity (0.28 Wh/kgK) converted to Watts.

Q5: Should I calculate for each surface separately?
A: For best results, calculate each element (walls, windows, roof) separately and sum the results.