1. What is a House Heat Loss Calculator?

Definition: This calculator estimates the heat loss of a building in watts based on U-values, surface areas, temperature differences, and ventilation losses.

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

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Total heat loss (Watts)
• \( U \) — U-value of building element (W/m²K)
• \( A \) — Surface area (m²)
• \( \Delta T \) — Temperature difference (Kelvin)
• Ventilation — Additional heat loss from air changes (W)

Explanation: The calculator sums heat loss through all building elements plus any additional ventilation losses.

3. Importance of Heat Loss Calculation

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

4. Using the Calculator

Tips:

• U-value: Default 2.5 W/m²K (typical for uninsulated walls)
• ΔT: Default 21K (difference between 21°C indoor and 0°C outdoor)
• Calculate each building element separately and sum the results

5. Frequently Asked Questions (FAQ)

Q1: What are typical U-values in UK homes?
A: Ranges from 2.5 (uninsulated) to 0.15 (well-insulated) W/m²K depending on construction.

Q2: How do I calculate ventilation losses?
A: Use: 0.33 × air changes per hour × volume × ΔT (or use 10-20% of fabric loss as estimate).

Q3: What temperature difference should I use?
A: Standard UK calculation uses 21K (21°C indoor vs 0°C outdoor).

Q4: How accurate is this calculator?
A: Provides good estimates but professional assessment recommended for precise calculations.

Q5: Does this account for thermal bridging?
A: No, consider adding 10-15% to account for thermal bridges in typical UK construction.