When you search for a modern rental property in Germany, you will often see two properties that look almost identical — same size, similar location, comparable design — but with a notable difference in their energy label. One says KfW-40. The other simply says Neubau (new build). The monthly rents are similar, but the running costs could be very different indeed.
This guide explains exactly what separates a KfW-40 new build from a standard new build, what it means in practice for your heating bills, and why — if you are choosing between the two — the KfW-40 property is almost always the better long-term choice for tenants.
What Is a Standard New Build in Germany?
In Germany, all new residential buildings must meet the minimum energy requirements set by the Gebäudeenergiegesetz (GEG) — the Building Energy Act. A standard new build meets these minimum requirements and nothing more. It will typically achieve energy class B or sometimes A-, and it is a significant improvement over older stock.
A standard new build will usually have:
- Double-glazed windows
- Standard wall insulation meeting GEG minimums
- A modern gas or heat pump heating system
- Basic ventilation (usually via openable windows)
This is perfectly adequate housing. But it is not the same as a KfW-40 building — and the difference in running costs can be substantial.
What Is a KfW-40 New Build?
A KfW-40 property (officially: Effizienzhaus 40) meets the standards set by the Kreditanstalt für Wiederaufbau (KfW), Germany’s state development bank. The 40 refers to the primary energy demand: a KfW-40 building consumes no more than 40% of the energy that an equivalent GEG reference building would require.
To reach this threshold, the building must go significantly beyond the legal minimum in several areas:
| KfW-40 Standard — What Is Required:Triple-glazed windows — three panes with low-emissivity coatingHigh-performance external insulation — full thermal envelope, no cold bridgesAir-source heat pump — instead of gas boilerMVHR ventilation — mechanical ventilation with heat recovery (85-90% heat recapture)Rooftop photovoltaic system — solar electricity generation |
The Real Difference: Running Costs
Here is where the two property types diverge most dramatically — and where the choice matters most to tenants.
Standard New Build — Typical Energy Costs
A standard new build home of 120 m² in Germany might have a primary energy consumption of around 75–100 kWh/(m²·a). At current energy prices, annual heating and hot water costs for a family in this type of property typically run to €900–1,400 per year.
KfW-40 New Build — Typical Energy Costs
The same 120 m² property built to KfW-40 standard, heated by a heat pump and supported by a photovoltaic array, might achieve a primary energy consumption of 30–40 kWh/(m²·a). Annual heating costs can fall to €300–600 — a saving of €600–800 per year compared with a standard new build, and far more compared with older rental stock.
The German Federal Environment Agency estimates that tenants in certified energy-efficient new builds spend up to 60–70% less on heating than those in typical existing-stock properties. While the comparison between KfW-40 and a standard new build is less dramatic than that, it is still meaningful — particularly as energy prices remain volatile.
Comfort Differences You Will Actually Notice
Beyond the bills, KfW-40 buildings simply feel different to live in. The combination of triple glazing, full thermal insulation and mechanical ventilation creates a noticeably more comfortable indoor environment:
- No cold walls or cold spots — the thermal envelope eliminates the cold bridges that make corners and wall junctions feel chilly in standard builds
- Consistent temperature — the building holds heat exceptionally well, meaning less active heating is needed
- Fresh air without draught — the MVHR system continuously circulates fresh air without the heat loss of opening windows in winter
- Cooler in summer — the same insulation that holds heat in winter keeps summer heat out, reducing the need for air conditioning
- Lower noise levels — triple glazing provides significantly better acoustic insulation than double glazing
What About the Rent? Is a KfW-40 Property More Expensive?
In some cases, yes — a KfW-40 property may command a modest premium in cold rent compared with a standard new build. However, when you factor in the savings on heating and electricity, the total monthly cost (Warmmiete — cold rent plus utilities) is often comparable or even lower.
| Example Comparison (120 m² family home):Standard new build: €1,500 cold rent + €150/month heating advance = €1,650 WarmmieteKfW-40 new build: €1,600 cold rent + €60/month heating advance = €1,660 Warmmiete |
In this example, the KfW-40 property costs €100 more per month in cold rent — but the total monthly outgoing is almost identical. And the KfW-40 tenant gets a significantly more comfortable, future-proofed home.
A Real-World Example: KfW-40 Terraced Houses Near Ulm
If you are looking for KfW-40 terraced houses for rent near Ulm, the Riverside Wohnpark in Herbrechtingen is one of the few current developments in the region that meets the full KfW-40 standard. The development offers 48 modern family homes of 120 m², each with a private garden, fitted kitchen, photovoltaic panels, glasfibre broadband and two parking spaces with EV charging pre-installation.
Net cold rents start from €1,635 per month — and with the energy savings of the KfW-40 standard, the total Warmmiete compares very favourably with standard new builds in the Ulm region. For families looking for modern family homes to rent in Herbrechtingen, it is one of the most complete packages currently available.
Summary: Which Should You Choose?
If you have the choice between a KfW-40 new build and a standard new build at similar price points, the KfW-40 property wins on almost every measure that matters over the medium and long term:
- Lower total monthly costs once heating and electricity are included
- Greater comfort — no cold spots, fresh air, better acoustics
- Future-proofed — less exposed to gas price spikes and energy market volatility
- Better for the environment — lower carbon footprint
- Stronger tenant protection — landlords of energy-efficient properties have less justification for modernisation rent increases
The only reason to choose a standard new build over a KfW-40 is if the location or layout is significantly better, or if the price difference is too large to justify. In most cases, the KfW-40 property is the smarter long-term choice.
