The Three-Liter House - Building with the Environment at a Glance

The Three-Liter House - Building with the Environment at a Glance

The energy age has spawned some terms that say little to the layman at first. What is, for example, a three-liter house?

The Energy-Saving Ordinance

Since 2002, the Energy-Saving Ordinance, or EnEv, has set the energy standards that a properly planned building must meet in terms of energy consumption. Energy-saving system technology and thermal protection are designed to ensure efficiency. Instead of the useful energy, the final energy is crucial for the energy efficiency calculation.

Under the concept of transmission heat, the regulation assesses room heat that is released outside the walls. In a nutshell, the EnEv succeeds in creating life cycle assessments for buildings. For this life cycle assessment, the most important factor is the primary energy demand of a building compared to a house of its own, but of technically ideal standards.

For balance sheet types according to EnEv, there will soon be separate names, such as the passive house or the efficiency house 40, 55 and 70 .

Balance sheet types according to EnEv - Passive Houses and Efficiency Houses

Passive Houses and Energy Efficiency Houses are low-energy houses that meet the EnEv standard.

The Efficiency House 70 reaches a maximum of 70 percent of the maximum values ​​that have been set since the 2009 Energy Saving Ordinance as the limits of the permissible annual primary energy demand. The annual primary energy demand for buildings in this efficiency class is 60 kWh per square meter.

Buildings in efficiency class 55 follow other standards. They reach the maximum values ​​set by EnEv 2007 for a maximum of 55 percent. They have an annual primary energy requirement of 40 kWh per square meter. The airtight energy efficiency house 40 offers an ultimate. It reaches an annual primary energy requirement of 30 kWh per square meter.

For passive houses, the focus is on the need for heating energy instead of the primary energy requirement for the year. A passive house has a heating energy requirement of 15 kilowatts per hour per square meter per year. If one converts this statement to fuel oil, this results in an annual requirement of 1.5 liters for every square meter of the passive house.

The three-liter house as variable size

The three-liter house also meets EnEv standards. Buildings of this type require a maximum of three liters of heating oil per square meter per year for ventilation and heating. For a heating system with natural gas that corresponds to 2.9 m³, with electricity it is 11.2 kilowatts per hour and with wood 7.1 kilograms. In this way, the three-liter house, based on the EnEv standards, saves up to 70 percent energy per year. Compared to a conventional construction, the ultra-low-energy house needs only one-third of its heating energy.

What's more, hiding behind a three-liter house remains unanswered. The quality of the building envelope is at the center of attention in the designation, while the investment technique is less involved. Often, experts therefore recommend that construction projects be planned more in line with the principles of efficiency house guidelines, as their values ​​and requirements are more clearly defined.

In order to transform a building into an efficient three-liter house, the client carries out the thermal insulation of the outer wall with a thickness of 45 centimeters. Heat pumps, triple glazed heat shields and window frames with thermal insulation are also recommended. Energy-efficient heating and a solar thermal hot water system are also helpful.

Three-liter house residents benefit from the recommended south-facing glazing. On sunny days, the interior of the house heats up and distributes itself through comfort ventilation in the house. A buffer tank absorbs this heat and thus feeds the water. It also gives off heat on low-temperature days

The comfort ventilation fulfills an additional function in addition to the heat distribution: It transfers the warm air to the fresh air outside and directs fresh air into rooms that have high air quality requirements. On low-temperature days, an underground storage tank will warm that air.

KfW Bank is supporting the renovation and construction of a three-liter house as long as it corresponds to one of the three energy efficiency houses 40, 55 or 70. With the measures described here, these claims meet. Promotion and environmental protection is so nothing in the way, as long as builders enjoy the term with caution. Not every three-liter house is an ultra-low energy house, because the term is not officially defined as such.

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