What is a passive house? According to the definition from PHI (Passivhaus Institut), passive houses are extremely energy efficient, comfortable and at the same time affordable. They provide a comfortable indoor climate both in summer and in winter, without the need for a conventional source of heating. This concept can be applied in any construction. A European standard bears the name of passive house, when the passive energy of the solar radiation captured from the outside and then supplied as thermal energy by some devices and the occupants of the house, is sufficient to keep the house at a comfortable indoor temperature during the cold season. An important component of the concept of passive houses are efficient technologies that minimize the energy consumption from other sources (especially electricity for household appliances). The objective is to keep total heat, hot water and electricity consumption below 42 kWh / m² * year.
Criteria for a passive house per square meter of living area:
maximum 10 W / m² constant heat requirement;
maximum 15 kWh / m² required annually for space heating;
maximum 42 kWh / m² total annual energy requirement.
The principles of a passive house:
efficient insulation
sealed envelope
no thermal bridges
triple pane windows
south orientation
heat recovery ventilation (HRV)
solar panels
vegetation for seasonal shading
Passive houses are distinguished by high thermal comfort and superior indoor air quality. High thermal comfort means comfortable and constant temperatures inside the house, without air currents, thus eliminating the risk of condensation and mold.
One of the basic elements in the construction of a passive house is the installation of an innovative heat recovery ventilation system. With the help of it, the vitiated air from the rooms with high humidity and odors (kitchen, bathrooms, laundry, etc.) is extracted and evacuated from the building, except heat, which is recovered and used for heating the fresh air that is permanently introduced in the house at a comfortable temperature. Thus, one of the main advantages of a passive house is the quality of the indoor air. It is permanently fresh, with extremely low concentrations of CO2, formaldehyde and volatile chemical compounds. At the same time, dust, emissions and allergens from outside are captured by the filters of the ventilation system. Another significant advantage is the very high energy efficiency. The energy consumption for heating a passive house is lower by more than 75-95% compared to similar consumption of a conventional house.
The PH (Passive House - certified by PassivHaus Institut) is the highest standard in the world for energy efficient buildings at the moment. The passive house must comply with extremely demanding requirements regarding the energy consumption for heating and cooling, the primary energy requirement or the degree of air tightness of the house envelope. In order for such a house project to meet all the necessary criteria, a team of specialists is required, and the energy balance must be achieved through a special software dedicated to passive building projects (PHPP - Passive House Planning Package) throughout the design process.
Passive houses can be built from any material, as long as the design principles are respected. The details of the execution and the way of putting it into operation are essential for obtaining the passive house certification.
How much does a passive house cost? Contrary to the popular belief regarding the costs of building a passive house, in general they are 10-15% higher compared to a conventional house. For larger buildings this difference is only 5-8%. However, these costs are recovered within 5-10 years of use, through reduced amounts of used energy. Even more, those who own an energy efficient home and produce even more green energy than is necessary for their own consumption, can become prosumers, thus generating negative electricity bills.
What is nZEB? The near zero energy building (nZEB) is characterized by low energy consumption from fossil sources and uses renewable (non-fossil) energy sources, in a proportion established by the procedure for defining minimum requirements, in accordance with the provisions of Articles 4 and 5 of Directive 31/2010 / EU.
According to the same European Directive 31/2010 / EU, until December 31, 2020, all new buildings will be buildings whose energy consumption is almost zero.
According to the legal requirements and provisions in force, a nZEB type building is defined and configured energetically taking into account the following elements:
the architectural configuration of the building implies the observance of the principles of sustainable development (including a high degree of energy performance of the building elements that will lead to a minimum energy requirement);
ensuring the need for energy, in particular, from high efficiency urban / district networks;
equipping the building with renewable energy sources, located either on the building or on the land owned by the building (analysis at the urban zoning project stage).
The level of primary energy consumption in the definition of nZEB - the individual dwelling for the climatic zone II in Romania is 111 kW / m2 / yr.
Through the “Green House” program started by the Ministry of the Environment, certain expenses regarding the energy efficiency of the houses are subsidized. The beneficiaries of the subsidies can receive up to 20,000 RON for the purchase of photovoltaic systems. The first step towards energy efficiency of a home refers to the thermal insulation of the building, the walls, and the installation of energy efficient windows and doors. There is no point in investing in an alternative source of energy such as solar panels or heat pumps, if thermal energy is lost through the walls. For windows, the frame is very important, but also the glass. It is recommended to use 3-pane windows.
Unlike passive houses, the concepts of eco house, green house or low energy house are very vague, interpretable concepts. There is no institution that imposes certain requirements, at least minimal, so that a building can be included in one of these categories.