Energy Performance Certificate & Ventilation: What You Need to Know
The energy performance certificate is mandatory for sales and rentals – and it has long been more than a formal document. Potential buyers and tenants are increasingly paying attention to the energy class, as it directly determines future ancillary costs. A building with a poor energy rating is harder to market and achieves noticeably lower prices.
What many don't know: A modern ventilation system with heat recovery can significantly improve the energy rating and thus increase the property value – often with less effort than a complete facade insulation. This guide shows you how significant the effect is, which systems are worthwhile, and what landlords need to consider legally.
What is in the energy performance certificate?
The energy performance certificate makes the energy status of a building comparable at a glance. The core of the document is the energy performance indicator: It states how much energy the building requires per square meter of living space per year. The lower this value, the better the energy class – and the lower the heating costs for the residents.
Basically, there are two variants: the consumption-based certificate, which is based on actual consumption data from recent years, and the demand-based certificate, which calculates the theoretical energy demand based on the building structure and plant technology. For evaluating modernization measures such as a ventilation system, the demand-based certificate is more informative because it reflects the technical quality of the building independently of user behavior.
Classification is done in classes from A+ to H. For orientation:
- Class A+: below 30 kWh/m²·a
- Class B: 75–100 kWh/m²·a
- Class F: 165–200 kWh/m²·a
- Class H: over 250 kWh/m²·a
How does a mechanical ventilation system improve the energy rating?
To understand why a ventilation system improves the energy performance certificate, it helps to look at the heat balance of a building: In addition to losses through walls, roof, and windows, a considerable part of the heating energy is simply lost through ventilation. Every time warm indoor air escapes through an open window, the incoming cold outside air must be completely reheated.
A controlled domestic ventilation system with heat recovery addresses exactly this: It transfers the heat from the exhaust air to the fresh supply air before it enters the rooms. Most of the ventilation heat thus remains in the building instead of being wasted. Since ventilation losses are the largest item in heat demand after the walls, this effect is directly reflected in the energy performance indicator:
| Before MVHR | After MVHR | Improvement |
|---|---|---|
| F (170 kWh/m²·a) | C (90 kWh/m²·a) | −47 % |
| E (140 kWh/m²·a) | B (80 kWh/m²·a) | −43 % |
| D (115 kWh/m²·a) | A (50 kWh/m²·a) | −57 % |
One class better means approximately 10–20% higher sales price for the property. In addition, there are the soft factors: a building with controlled ventilation offers consistently fresh air, protects against mold, and is thus a real quality feature for tenants. The guide on Planning a comfort ventilation system with heat recovery explains how to properly design a MVHR system.
Obligations for landlords and GEG requirements
For landlords and sellers, the energy performance certificate is not a voluntary additional service, but a legal obligation with clear rules. Anyone advertising a property must already state the energy key figures in the advertisement – and at the latest during the viewing, the certificate must be presented unsolicited. These transparency obligations are intended to ensure that interested parties can realistically estimate the ongoing energy costs before committing.
Violations are not minor offenses: missing or delayed presentation can be penalized as an administrative offense. Those who regularly rent out or plan a sale should therefore check early on whether a valid certificate is available – and whether an energy improvement before marketing is worthwhile to increase the rating and thus the achievable price.
Important: Since 2014, the energy performance certificate must be presented during viewings. The energy key figures must be stated in real estate advertisements. Violations can result in a fine of up to €15,000.
The Building Energy Act (GEG) 2024/2025 also requires:
- For rental and sale: a valid energy performance certificate
- New construction: KfW Efficiency House 55 as a minimum
- For extensive renovation: 65% renewable energy obligation (heating)
- Ventilation maintenance certificate for multi-family houses
Which ventilation system increases value?
Not every ventilation solution has the same strong effect on the energy performance certificate. The greatest leverage comes from systems that actively support heat recovery or combine several functions – for example, devices that combine ventilation, heating, and hot water preparation in one unit. Such combi units not only improve the ventilation balance but ideally also replace a fossil heat generator, thus doubling the energy rating improvement.
Important for the order of measures: The plant technology only fully develops its effect in a reasonably airtight building envelope. Anyone who owns a completely uninsulated house should therefore first address the greatest weaknesses of the envelope and adapt the ventilation technology accordingly. However, solid individual solutions such as decentralized fans with heat recovery already bring measurable improvements – especially where a central system is not feasible.
Maximum Effect
- Nilan Compact P (with active heat recovery)
- Nilan Combi 302/400 (integrated heating)
- Brine-to-water heat pump plus ventilation
- Photovoltaic system for electricity
- First improve insulation
Solid Effect
- S&P CAD-HE ventilation
- Nilan Comfort 200 (passive heat recovery)
- Bathroom fan with heat recovery (Blauberg Vento)
- Decentralized fans per room
Whether a central or decentralized system is better suited to your building is shown in the comparison Central vs. Decentralized Ventilation. Suitable devices can be found in the categories Ventilation Systems and Heat Pumps.
With the BEG funding 2026, you receive up to 70% government funding for heat pump ventilation – and the energy performance certificate value improves at the same time.
Frequently Asked Questions
How long is an energy performance certificate valid?
10 years from issue. However, after extensive energy modernization, a new issue is worthwhile so that the improved rating is also documented.
Which class does an apartment building need?
For new buildings from 2024, at least KfW-EH 55 (Class B–C). In existing buildings, it varies greatly.
Can a ventilation system alone improve the class?
Yes, an MVHR system with active heat recovery can bring 1–2 classes of improvement. Combined with insulation, 3+ classes are possible.
Who is allowed to issue an energy performance certificate?
Energy consultants from the dena list or certified experts (e.g., HVAC masters with additional qualifications).
Conclusion
A ventilation system with heat recovery is one of the most effective levers for a better energy performance certificate – with a direct impact on property value and marketability. Because ventilation losses are among the largest items in heat demand, an MVHR system often improves the energy rating by one to two classes, and even more significantly in combination with insulation. Landlords thus also meet the GEG requirements and make their property fit for future tightening of regulations. By combining the investment with government funding, they significantly reduce their own costs – and benefit from a better indoor climate and lower heating costs from day one.
Everything about controlled domestic ventilation can be found in the ventilation assortment of wohnungstechnik.de.
