How this instrument works
Passive House (Passivhaus) is a rigorous, internationally recognised building-performance standard developed by the Passive House Institute. Its signature requirement is that space-heating demand must not exceed 15 kWh per square metre of treated floor area per year — roughly a tenth of what conventional buildings in many countries typically use, achieved through superinsulation, airtight construction, and heat-recovery ventilation rather than a bigger furnace.
That 15 kWh/m²/year figure is a fixed, well-established standard used as-is by this calculator. The 'conventional baseline' it's compared against, however, is genuinely not a fixed international constant — heating demand for existing buildings varies enormously by country, climate zone, and building age, so this calculator exposes it as an adjustable input with a disclosed rough default of 150 kWh/m²/year, in the range commonly cited for existing European building stock by sources like BPIE's 'Europe's Buildings Under the Microscope.'
The calculator multiplies the gap between your baseline and the Passive House threshold by your floor area to get annual energy saved, converts that to a currency saving using your energy price, and divides the extra construction cost of meeting the standard by that annual saving to get a simple payback period in years — the point at which the upfront investment has paid for itself in avoided heating costs.
- Enter Heated floor area — your building's treated floor area in square metres.
- Adjust Conventional building's heating demand if you know your local baseline; default is 150 kWh/m²/yr.
- Enter Heating energy price — your cost per kWh of heating energy.
- Enter Extra construction cost for building to Passive House standard.
- Read Annual energy saved, Annual cost savings, and Simple payback period.
Worked example — a 150 m² home against a European baseline
A 150 m² home built to Passive House standard (15 kWh/m²/yr) instead of a conventional baseline of 150 kWh/m²/yr — a rough figure for existing European building stock — saves (150 − 15) × 150 = 20,250 kWh of heating energy every year.
At an energy price of $0.10/kWh, that's 20,250 × 0.10 = $2,025 in annual heating savings. Against an extra construction cost of $15,000 to meet the Passive House standard, the simple payback period is 15,000 ÷ 2,025 ≈ 7.41 years — after which the upfront investment has been fully recovered in avoided heating costs, with decades of further savings typically still ahead given a building's usual lifespan.
Questions
What exactly does the Passive House standard require?
Its headline requirement is that space-heating demand must not exceed 15 kWh per square metre of treated floor area per year, achieved primarily through superinsulation, airtight construction, high-performance windows, and mechanical ventilation with heat recovery rather than a larger heating system. The Passive House Institute also sets airtightness and other performance criteria, but the 15 kWh/m²/yr heating threshold is the standard's defining number.
Why is the conventional baseline adjustable instead of a fixed number like the Passive House threshold?
Because unlike the Passive House standard, which is a single internationally-defined target, 'conventional' heating demand varies hugely by country, climate, and building age — an older, poorly insulated building in a cold climate can use far more than 150 kWh/m²/yr, while a newer, moderately efficient building might use much less. The 150 kWh/m²/yr default here is a rough placeholder for aging European building stock, not a claim about your specific building or location.
Does the payback period account for anything other than heating costs?
No — this is a simple payback calculation based purely on avoided heating energy costs, and doesn't factor in other potential Passive House benefits like improved comfort, better indoor air quality, reduced cooling costs in summer, or any resale-value premium, nor does it account for financing costs, inflation, or future energy price changes. Treat the payback figure as a first-order estimate for the heating-cost dimension alone.
Is Passive House the same thing as 'net-zero' or 'zero-energy' building?
No — Passive House specifically targets ultra-low space-heating demand through building envelope performance, while net-zero or zero-energy standards typically target total annual energy consumption being offset by on-site renewable generation like solar panels. A building can be Passive House certified without being net-zero, and vice versa, though the two approaches are often combined in practice since a Passive House's low heating demand makes reaching net-zero with a smaller renewable-energy system much easier.
Does a smaller gap between baseline and the Passive House threshold ever make it not worth it?
Yes, mathematically — if a building's conventional baseline is already close to the 15 kWh/m²/yr threshold (an already energy-efficient building, for example), the annual energy saved shrinks and the payback period lengthens accordingly, which the calculator will show directly. In that case, other reasons to build to Passive House standard, like comfort or long-term resilience to energy price volatility, may matter more than the pure cost-payback math.