Ventilation Plan

The ventilation plan is a design document that describes how a building is supplied with sufficient fresh air and how moisture and pollutants are removed-particularly in the case of airtight building envelopes, which are standard in low-energy and passive houses. It has been mandatory for new buildings and comprehensive renovations since the enactment of the GEG (Building Energy Act) and DIN 1946-6. A missing or inadequate ventilation concept can lead to moisture damage, mold, and health hazards.

Legal Requirements According to DIN 1946-6

DIN 1946-6 (Ventilation and Air Conditioning - Ventilation of Residential Buildings) stipulates that whenever a significant change is made to the building envelope-such as window replacement, facade insulation, or roof renovation-it must be determined whether natural infiltration is still sufficient or whether a mechanical ventilation system is necessary. The result of this assessment is the ventilation concept.

Specifically, the following trigger the obligation to develop a ventilation concept: the replacement of more than one-third of all windows and exterior doors, or the insulation of more than one-third of the roof area or basement ceiling. It determines whether window ventilation, an exhaust air system, a supply/exhaust air system with heat recovery, or another solution will be used. For new buildings, the ventilation concept is a mandatory component of the building permit documents and is verified no later than during the blower door test.

Overview of Ventilation Systems

Depending on the requirements, various systems may be considered. Natural ventilation (windows, exterior wall openings) works in drafty older buildings but fails in insulated buildings with an airtight envelope. Exhaust systems extract stale air from the kitchen and bathroom; fresh air enters through gaps or exterior wall vents-sufficient for lightly renovated buildings but not for airtight new constructions.

Central supply and exhaust air systems with heat recovery (WRG) are considered the optimal solution for new buildings-they exchange air in a controlled manner and recover up to 90% of the heat, which significantly reduces heating requirements. Decentralized ventilation units are suitable for renovating individual rooms and can be retrofitted without a duct network. The choice of system has a significant impact on energy consumption, comfort, and maintenance requirements.

Development of the ventilation concept: Who is authorized to develop it?

The ventilation concept in accordance with DIN 1946-6 requires building physics calculations and must not be developed by laypeople. Those authorized to do so include energy consultants, specialist engineers (building services, building physics), and architectural firms with the appropriate expertise. For subsidy programs from KfW or BAFA, the signature of a certified energy consultant (as listed on the Energy Efficiency Experts List) is often mandatory. The cost of a professional ventilation concept ranges from €300 to €1,000, depending on the size of the building.

A correctly prepared ventilation concept forms the basis for selecting and sizing the ventilation system and protects the owner in the event of damage: If mold develops despite a properly designed system, the cause is more likely to be user behavior than the design.

Practical Tip for Homeowners in Nuremberg and Franconia

Anyone renovating their home in Nuremberg or the metropolitan region to improve energy efficiency-such as replacing windows and insulating the facade-must have a ventilation concept prepared in accordance with DIN 1946-6. Many homeowners overlook this step, which later leads to mold damage. Before or at the same time as planning the renovation, hire an energy consultant to develop the ventilation plan. Funding from KfW and BAFA for energy-efficient renovations often requires a proper ventilation plan.

Especially in Nuremberg’s Wilhelminian-style neighborhoods-such as Gostenhof, Südstadt, or St. Leonhard-older buildings are being fitted with new windows without a ventilation plan being commissioned. The result is mold problems in bedrooms and living areas, which not only cause structural damage but can also lead to rent reductions. We can help you find qualified energy consultants in the region.

Frequently Asked Questions

When is a ventilation concept required?

Whenever more than one-third of the windows in an existing building are replaced or one-third of the roof or basement ceiling is insulated. For new construction, it is always required. The exact thresholds are specified in DIN 1946-6.

How much does it cost to develop a ventilation concept?

The cost of a professional ventilation concept in accordance with DIN 1946-6 ranges from €300 to €1,000, depending on the building’s size and complexity. For larger properties or apartment buildings, the costs may be higher.

As the owner, can I create the ventilation concept myself?

Technically possible, but not recommended. DIN 1946-6 requires building physics calculations. Errors in the concept can lead to inadequate ventilation or mold growth. For subsidy programs, the signature of a certified energy consultant is often required.

Does the ventilation plan have to be submitted with the building permit application?

For new construction, yes-it is a mandatory part of the building permit application documents. For renovations involving significant changes to the building envelope, it must be prepared but is not required to be submitted to the building authority. It primarily serves as a planning basis and liability protection for the designer.

How much does a controlled residential ventilation system with heat recovery cost?

The investment costs for a central supply/exhaust air system with heat recovery typically range between 8,000 and 20,000 euros, depending on the size of the house and the scope of work. Installation is less expensive for new construction, as the ducts are planned from the outset. In existing buildings, duct shafts must be retrofitted or decentralized units without a duct network must be used, which increases the cost. The ongoing operating costs are low: electricity for the fans is typically less than 100 euros per year; filter replacement (every six to twelve months) costs 30 to 80 euros per filter. This is offset by energy savings, which can amount to several hundred euros annually in a well-insulated home with an efficient heat recovery system. KfW subsidy programs support the installation of ventilation systems with heat recovery as part of energy-efficient renovations.

What maintenance does a ventilation system require?

A controlled residential ventilation system must be regularly maintained to ensure it operates hygienically and efficiently. This includes regular filter changes (coarse and fine dust filters every 6-12 months), annual cleaning of the heat exchanger unit, and, for duct networks, regular inspection and, if necessary, cleaning of the air ducts. Neglected maintenance leads to increased energy consumption, reduced air quality, and, in the worst case, the spread of germs and mold spores through the ductwork. We recommend agreeing on a maintenance contract with the installation company during the system planning phase.

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