1. What is a Residential Heat Loss Calculator?

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

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

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Total heat loss (Watts)
• \( U \) — U-value (thermal transmittance in W/m²K)
• \( A \) — Area of the surface (m²)
• \( \Delta T \) — Temperature difference between inside and outside (Kelvin)
• Ventilation loss — Heat loss through air changes (Watts)

Explanation: The calculator sums the conductive heat loss through building elements and adds the ventilation heat loss.

3. Importance of Heat Loss Calculation

Details: Accurate heat loss calculations ensure proper heating system sizing, energy efficiency, and comfort while preventing over- or under-heating.

4. Using the Calculator

Tips: Enter the U-value of the building element, its area, the temperature difference, and any ventilation losses. For complete building analysis, calculate each element separately and sum the results.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical U-value for walls?
A: Modern insulated walls typically have U-values between 0.15-0.30 W/m²K, while older walls may be 1.0-2.0 W/m²K.

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

Q3: What affects ventilation loss?
A: Air changes per hour, building volume, and temperature difference. Use 0.33 × volume × air changes × ΔT for estimation.

Q4: Should I use worst-case ΔT?
A: For heating system sizing, use the design temperature difference for your location (often -5°C to -15°C outside).

Q5: How accurate is this calculation?
A: It provides a good estimate but doesn't account for thermal bridges, solar gain, or internal heat sources.