About this calculator

Passivhaus certification requires ≤ 15 kWh/m²·yr for space heating (PHPP). EnerPHit (retrofit) = 25. Quick estimate: heat loss W/m² × heating hours / 1000.

Frequently asked questions

What does the Passivhaus Heat-Demand Check do?

Quick PHPP-style check: is your annual heating demand inside the 15 kWh/m²a Passivhaus limit? Passivhaus certification requires ≤ 15 kWh/m²·yr for space heating (PHPP). EnerPHit (retrofit) = 25. Quick estimate: heat loss W/m² × heating hours / 1000.

Is the Passivhaus Heat-Demand Check free to use?

Yes. Every calculator on Calcurly.com is free, works in your browser without sign-up, and can be embedded on your own website.

How accurate is the Passivhaus Heat-Demand Check?

Results are calculated in real time using industry-standard formulas. Treat the output as a well-informed estimate — always cross-check with local regulations, product datasheets, or a qualified passivhaus check professional before committing to a purchase or a job.

What inputs does the Passivhaus Heat-Demand Check need?

Enter values for: Treated floor area (m²), Design heat load (W/m²), Heating hours/yr. Sensible defaults are pre-filled where possible so you can start with a single change.

Can I embed the Passivhaus Heat-Demand Check on my own website?

Yes — copy the iframe snippet at the bottom of this page, or use the Embed Generator to customise the size. The embedded version stays in sync with the live calculator on Calcurly.com.