Heat Load Calculator - EN 12831-1
Heat load calculations in minutes, not hours.
The heat load calculator in HeatAlgo is a browser-based heat load calculation compliant with EN 12831-1 (ISO 6946, ISO 13370), room by room - built for heating installers. See every wall layer, every U-value, the split between transmission and ventilation losses. Nothing is hidden.
Context
Why heat load calculations matter now
Clients ask about heat demand calculations while planning the investment - when choosing the heat source, radiators, or underfloor heating. If you can calculate and present it, you walk into that conversation prepared.
Until now, the calculations meant expensive licensed desktop software or outsourcing every project to an engineer. Small installation companies had no good option. They either paid up or lost the job.
Installers who can produce heat load calculations themselves win on every front: they are faster than the competition, retain full control over the result, and keep the entire fee. It is a concrete advantage in every client conversation.
Step by step
How to calculate the heat load
Enter building data
Provide dimensions, location, and climate zone. The system fills in sensible defaults, and you change only what differs from the typical values.
Features
Everything you need for the heat load calculation
Comparison
HeatAlgo vs traditional software
Comparison of tools for heat load calculations
HeatAlgo
Traditional software
Free forever, reports from €25
Price
A per-seat licence
Price
Browser
Installation
PC (Windows)
Installation
None
Training
Weeks
Training
EN 12831-1 + ISO 6946 + ISO 13370
Full compliance covers residential buildings with natural, mechanical, or MVHR ventilation, without air transfer devices (ATDs).
Methodology
Varies
Methodology
Every step visible
Transparency
Often a black box
Transparency
Yes, simple and readable
PDF report
Yes, complex
PDF report
FAQ
Frequently asked questions
What methodology are the calculations based on?
The heat load calculator implements EN 12831-1 (room-by-room building heat load) with EN ISO 6946 (thermal resistance of building components) and EN ISO 13370 (ground). The result includes heat losses, U-values, the transmission/ventilation split and an additive thermal-bridge surcharge per EN 12831-1 Annex B.2.1 (ΔU_TB). Useful for quick building assessment and client presentations - a certified energy audit may still be required for formal grant applications. Full compliance covers residential buildings with natural, mechanical, or MVHR ventilation, without air transfer devices (ATDs).
Can I add custom wall layers?
Yes. You can define any wall composition layer by layer, with your own thicknesses and lambda values. Or pick a typical construction from the list.
How quickly do I get a result?
Minutes. Enter the building data and the calculations generate automatically. The result is instant.
What does HeatAlgo cost?
Your account is free forever - calculate the heat load without limit, no card required. You only pay for the full report: €25 per project, or unlimited on the Installer subscription from €83.25/mo billed annually.
How long does an audit take?
Minutes. It depends on the building, but a typical single-family home takes 10-15 minutes on the first visit. Subsequent projects go faster thanks to saved constructions.
Will the result help with a Clean Air grant application?
HeatAlgo generates heat load calculations per EN 12831-1. The result is useful for initial building assessment and client conversations. A certified energy audit performed by a licensed auditor may still be required for the formal grant application. Full compliance covers residential buildings with natural, mechanical, or MVHR ventilation, without air transfer devices (ATDs).
Does it support buildings with different wall types?
Yes. You can define a different layer composition for each building element: external wall, roof, floor, windows, and doors can each have different parameters.
Can I edit wall layers?
Yes. You can add, remove, or change any layer. You immediately see the effect on the U-value.
Calculate your first heat load today
Register, enter the building data, and see a result compliant with EN 12831-1 in minutes.
No payment card. Your projects and calculations stay forever.