Heat Loss Calculator UK

Heat Loss Formula:

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

U-Value (W/m²K):

Surface Area (m²):

Temperature Difference (ΔT in K):

Room Volume (m³):

Air Changes per Hour (ACH):

Total Heat Loss (W):

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1. What is a Heat Loss Calculator for UK Buildings?

Definition: This calculator estimates the heat loss of a building using the UK standard calculation method, considering both fabric and ventilation losses.

Purpose: It helps architects, builders, and homeowners determine heating requirements and improve energy efficiency in UK buildings.

2. How Does the Calculator Work?

The calculator uses the formula:

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

Where:

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

Explanation: The calculation combines heat loss through building fabric (first term) with heat loss through ventilation (second term).

3. Importance of Heat Loss Calculation

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

4. Using the Calculator

Tips: Enter the U-value of your building element, surface area, temperature difference (default 21K for 21°C inside and 0°C outside), room volume, and air changes per hour (default 0.5 for average UK homes).

5. Frequently Asked Questions (FAQ)

Q1: What is a typical U-value for UK homes?
A: For walls, modern homes aim for 0.3 W/m²K or better. Older homes might be 1.5 W/m²K or higher.

Q2: Why is 0.33 used in the ventilation formula?
A: This is the heat capacity of air (0.33 Wh/m³K) which converts air flow to heat loss.

Q3: What's a typical ACH value?
A: 0.5 for modern homes with good air tightness, 1.0 for older homes, up to 2.0 for very leaky buildings.

Q4: How do I account for multiple building elements?
A: Calculate each element separately and sum the results, or use an average U-value for the whole building.

Q5: Does this include heat gains?
A: No, this calculates heat loss only. For net heating requirement, subtract solar and internal gains.