The report presents a comprehensive assessment of residential building energy performance, focusing on the classification of buildings into efficiency classes from A+ to H based on specific end‑energy consumption. The classification ranges from less than 30 kWh m⁻² a for A+ to over 250 kWh m⁻² a for H, with corresponding approximate annual energy costs per square metre ranging from below €2 for A+ to €13 or more for H. These figures provide a clear benchmark for evaluating the economic impact of energy‑saving measures.

Technical results centre on heating supply options and insulation strategies. The study recommends renewable heating systems such as biomass boilers (pellets, wood chips, bark), heat pumps, and solar thermal collectors, often combined to meet winter demand efficiently. For district heating, the report notes that the choice of supply depends on local infrastructure and future decentralisation plans. Insulation performance is quantified through U‑values and required thicknesses. For example, a 60 mm wood‑fiber insulation plate combined with a 15 mm lime plaster layer yields a U‑value of 0.44 W m⁻² K⁻¹, while increasing the plate to 80 mm reduces the U‑value to 0.35 W m⁻² K⁻¹. Similar data for straw‑fiber panels show U‑values of 0.55 W m⁻² K⁻¹ at 60 mm and 0.48 W m⁻² K⁻¹ at 80 mm. The report also documents the use of a polystyrene‑free “Wärmedämmputz” (thermal‑insulating plaster) that achieves U‑values of 0.70 W m⁻² K⁻¹ at 20 mm, 0.60 W m⁻² K⁻¹ at 40 mm, and 0.55 W m⁻² K⁻¹ at 60 mm, while preserving the façade’s original appearance. These figures illustrate that natural materials can deliver competitive thermal performance without the environmental drawbacks of conventional rigid foams.

Case studies illustrate practical implementation. The Biohotel Amtshof in Langenargen was retrofitted with straw‑fiber panels and lime plaster, achieving a wall‑surface heating system integrated into the plaster. Another example shows an interior insulation scheme using 60 mm wood‑fiber plates, 15 mm lime plaster, and embedded wall‑heating pipes, resulting in a U‑value of 0.44 W m⁻² K⁻¹ and improved indoor climate. The report also discusses the challenges of adding external insulation to historic façades, recommending the use of “Wärmedämmputz” to maintain aesthetic integrity while improving thermal performance.

Collaboration details are less explicit. The report references contributions from architects (e.g., Architekturbüro R. Betz, Architekturbüro A. Weber) and material suppliers such as HAGA AG Naturbaustoffe, indicating a multidisciplinary approach that combines architectural design, engineering analysis, and material science. No formal consortium or funding body is named, and the timeframe of the project is not specified, suggesting that the work was carried out by a local team of professionals over several years, culminating in this publication. The absence of a stated funder implies that the project may have been supported by regional building authorities or industry partners rather than a national research grant.