Construction Calc Lab

Building Physics · Calculator

Heat Loss Calculator

Estimate steady-state transmission heat loss using area, U-value and temperature difference.

Project inputs

Enter your project values, then press Calculate.

How this calculator works

Estimate steady-state transmission heat loss using area, U-value and temperature difference.

Q = U × A × ΔT

How to use the Heat Loss Calculator

1. Enter project inputs

  • Envelope area (m²)
  • U-value (W/m²·K)
  • Indoor temperature (°C)
  • Outdoor temperature (°C)

2. Review the results

  • Temperature difference
  • Heat loss
  • Heat loss

3. Check the calculation

The calculator uses the following core relationship:

Q = U × A × ΔT

Sizing note: HVAC results are preliminary estimates and should be verified against a project-specific load calculation and manufacturer data.

Heat Loss Calculator Guide

A heat loss calculator estimates heat transfer through building surfaces.

Calculation formula

Heat Loss depends on Area, U-Value and Temperature Difference

Estimation tips

Insulation quality and building materials strongly affect heat loss.

Engineering note: Use these calculations for estimation and planning. Always confirm final designs according to project requirements and applicable standards.

Heat Loss Calculator FAQ

What does the Heat Loss Calculator calculate?

Estimate steady-state transmission heat loss using area, U-value and temperature difference.

What information do I need to use the Heat Loss Calculator?

The calculator uses inputs such as Envelope area (m²), U-value (W/m²·K), Indoor temperature (°C), and Outdoor temperature (°C). Use values from your drawings, measurements, product data, or project specifications.

How should I use the results from the Heat Loss Calculator?

Use outputs such as Temperature difference, Heat loss, and Heat loss as an early sizing estimate. Final HVAC selection should account for climate, envelope performance, ventilation, occupancy, equipment data, and a project-specific load calculation.