Calculadora de Casa Passiva (Economia)
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
Economia = (kWh_conv - kWh_passiva) × tarifa; CO₂_evitado = economia_kWh × 0,233; payback = custo_extra / economia
About this calculator
The Passive House (Savings) Calculator estimates the financial savings, payback period, and CO₂ emission reductions when choosing a passive construction over a conventional one. It compares the annual electricity consumption in kWh between the two models, applies the local energy tariff, and calculates the extra cost required to implement passive principles (such as thermal insulation, sealing, and mechanical ventilation). The result shows how many years it takes for this additional investment to pay off and how many kilograms of CO₂ are avoided per year.
The operation is simple: you enter the annual energy consumption of a conventional house (kWh) and a passive house (kWh), plus the extra cost of passive construction and the energy tariff (R$/kWh). The calculator then computes the annual savings in reais, the payback period, and the amount of CO₂ avoided per year, using the factor of 0.233 kg CO₂ per kWh saved (Brazilian average). This tool is useful for architects, engineers, and homeowners who want to assess the economic viability of a passive house.
Use this calculator when planning a construction or renovation and you want to compare long-term costs between a conventional and a passive building. It is especially relevant in regions with high energy tariffs or where incentives for sustainable construction exist. Remember that consumption values should be based on projects or energy simulations, not on generic estimates.
Caveats: results are approximate and depend on the accuracy of the input data. Passive house consumption can vary with climate, solar orientation, and occupant behavior. Also, the extra cost of passive construction can be difficult to estimate, as it includes specialized materials and labor. It is recommended to consult a professional for realistic values. The calculator does not consider inflation, tariff increases, or maintenance costs.
Frequently asked questions
What is a passive house?
A passive house is a construction standard that aims to drastically reduce energy consumption for heating and cooling, using thermal insulation, airtightness, high-performance windows, and mechanical ventilation with heat recovery.
How is the payback calculated?
The payback is calculated by dividing the extra cost of passive construction by the annual savings in reais. For example, if the extra cost is R$ 30,000 and the annual savings are R$ 3,000, the payback is 10 years.
Is the CO₂ factor (0.233) valid for all of Brazil?
This factor is a rough national average. The actual value varies by regional electricity mix. For greater accuracy, check the local emission factor.
Can I use the calculator for a renovation?
Yes, as long as you enter the consumption before and after the renovation and the extra cost of passive improvements. The calculation will be the same as for a new construction.
Does the calculator consider gas or other fuels?
No, it only considers electricity. If your house uses gas for heating, you should convert the consumption to equivalent kWh and include it in the electricity tariff or use another tool.