Passive House

The passive house standard includes several criteria, but the main one is the low annual heating demand – not more than 15 kWh/m2. It means the building essentially does not require a traditional heating system, as the necessary heat is provided by a modern ventilation system. A passive house is the apex of comfort, quality of living environment and energy-efficiency in construction. The building provides very high thermal comfort and excellent air quality. In a passive house, even in the coldest days of the winter, you will never feel discomfort between surfaces with different temperatures, such as between window glazing and ambient temperature. You will not feel tired because of the effect of CO2, and children will be able to avoid asthma-related problems, as fresh air constantly enters the passive house, after it has been warmed up to the temperature necessary for comfort.

As strange as it may seem, when thinking in the long term, a passive house will be cheaper than a “regular” contemporary house. In the 20 years since the construction of the first passive house, the standard has proven its viability and economy, and around 25,000 passive houses have already been built in Europe alone – mainly in Austria, Germany, and Sweden. The advantages of a passive house can be easily proven with calculations on heating and economy. However, it is best to experience it yourself by building a passive house for your family!

What ensures the economy of a passive house?

Why choose the passive house standard for the construction of a private house? A “regular” contemporary house has an annual heating demand of 120–150 kWh/m2; a passive house uses only 15 kWh/m2 per year. If we choose the prices of natural gas as the standard, the heating of a 150 m2 house after January 1, 2012 costs 2600 m3 × 0.5497 = 1,429 euros. We know that the cost of natural gas for households has increased by 555% over the past ten years, or by an average of 21% per year, and we can assume the price increase in the next ten years will not be smaller. In that case, in ten years the cost of a cubic meter of gas will be 0.5497 × (1+0.21)10 = 3.698 euros, and a total of 48,598 euros will be spent on heating over 10 years.

Let us assume that the construction of a “regular” house today costs 925 EUR/m2, while a passive house is 25% more expensive at 1155 EUR/m2. The “regular” version of the aforementioned 150 m2 house will cost 138,750 euros, while observing the passive house standard will increase the cost to 173,250 euros. The difference between the construction costs of both houses is 34,500 euros. If you build a passive house whose annual heating demand is only 15 kWh/m2, you will save 41,309 euros over the course of ten years. Inserting the numbers in formulas allows easily calculating that the additional cost of a passive house will pay off in as little as eight or nine years, after which the house will be “making money” for you. If we assume that the house is used for 15 years, the building and heating costs of a “regular” house will be 249,853 euros, while the total cost of a passive house will be only 184,419 euros. Thus, you will save 65,434 euros from the 9th to the 15th year of use.

Guntis Gradovskis,
Dipl.-Ing., energy auditor,
designer of passive houses