Passive House Savings Calculator

This calculator models a standard baseline building (Option A) against two high-efficiency tiers (Option B and Option C). First, total building costs are derived by multiplying the floor area (size) by the construction cost per square meter. Energy requirements are computed from specific energy demand metrics per square meter. Gas consumption is calculated by converting kilowatt-hours of energy demand into volume using the specified gas-to-kWh conversion factor, which is then multiplied by the unit gas price to determine annual heating expenses. Finally, financial savings equal the difference in annual heating costs between the baseline and the efficient tier, while the break-even period is determined by dividing the initial extra capital investment by the annual financial savings.

Consider a 150 square meter home. Option A (Standard Build) costs $2,000 per square meter, totaling $300,000, with an energy demand of 120 kWh/m² per year. Assuming a gas-to-kWh conversion rate of 10 and a gas price of $0.10 per unit, the baseline annual gas demand is 1,800 units, resulting in $180 in annual heating costs. Option B (Passive Tier) requires a 10% additional investment ($30,000 extra) but drops energy demand to 15 kWh/m² per year. Option B's annual gas demand drops to 225 units, costing $22.50 to heat. This yields an annual savings of $157.50 ($180 minus $22.50). Dividing the $30,000 extra investment by the $157.50 annual savings gives a break-even timeline of approximately 190.5 years.

When planning a passive house project, always factor in future energy price inflation, which can dramatically shorten your actual financial break-even timeline. Pay close attention to airtightness and thermal bridge elimination, as these components dictate whether your building will actually meet its targeted energy demand per square meter. Finally, consult local green building incentives or tax rebates, which can directly reduce your upfront capital investment and accelerate your return on investment.