Room Heat Loss Calculator UK

Heat Loss Formula:

\[ Q = U \times A \times \Delta T + 0.33 \times V \times ACH \times \Delta T \]

U-value:

W/m²K

Surface Area:

m²

Temperature Difference:

Room Volume:

m³

Air Changes per Hour:

1/h

Heat Loss (W):

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1. What is a Room Heat Loss Calculator?

Definition: This calculator estimates the heat loss from a room in watts using UK building standards and practices.

Purpose: It helps homeowners, architects, and builders determine heating requirements for rooms and buildings.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ Q = U \times A \times \Delta T + 0.33 \times V \times ACH \times \Delta T \]

Where:

\( Q \) — Total heat loss (Watts)
\( U \) — U-value of the building element (W/m²K)
\( A \) — Surface area of the element (m²)
\( \Delta T \) — Temperature difference between inside and outside (Kelvin)
\( V \) — Volume of the room (m³)
\( ACH \) — Air changes per hour (1/h)

Explanation: The formula calculates both fabric heat loss (through walls, windows, etc.) and ventilation heat loss (through air changes).

3. Importance of Heat Loss Calculation

Details: Accurate heat loss calculations are essential for proper heating system sizing, energy efficiency, and compliance with UK building regulations.

4. Using the Calculator

Tips: Enter the U-value, surface area, temperature difference, room volume, and air changes per hour (default 0.5 for typical UK homes). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical U-value for UK homes?
A: Modern UK building regulations require walls to have U-values around 0.3 W/m²K, windows around 1.6 W/m²K.

Q2: How do I determine air changes per hour?
A: 0.5 is typical for modern homes, 1.0 for older homes, and up to 1.5 for very leaky buildings.

Q3: What temperature difference should I use?
A: For heating design, use the difference between desired indoor temperature (e.g., 21°C) and winter design temperature for your location (e.g., -3°C outside = 24K difference).

Q4: Why is the ventilation factor 0.33?
A: This accounts for the heat capacity of air (0.33 W/m³K) and converts hours to seconds in the calculation.

Q5: Does this include heat loss through floors?
A: Yes, if you include the floor area and U-value in your calculations. Ground floors typically have U-values around 0.25 W/m²K.