Monolithic structural systems and material simplicity

The project introduces a novel one-layer construction strategy in each housing complex, reducing materials, composite primary sources, assembly complexity, and thus embodied carbon [4]. Each three-story walk-up housing block employs a different monolithic structural system: timber, masonry, and lightweight concrete (see Figure 2). Each material simultaneously performs structural, thermal, and enclosure functions, reducing the need for layered assemblies, synthetic membranes, composite materials, chemical adhesives, and finishing layers typically used in contemporary high-performance construction (see Figure 3) [5].

The timber house employs 30 cm thick solid timber walls with integrated milled air chambers to improve thermal performance without requiring additional insulation or conventional vapour barriers (see Figure 4) [6]. The thickness of the monolithic timber envelope enables thermal mass to minimize insulation [7]. Prefabrication, exposed untreated surfaces, and selective glueing enable efficient and economical construction [8]. The use of timber additionally highlights circularity as a renewable material capturing nearly twice the amount of carbon emitted during construction, as well as facilitating prefabrication and rapid assembly [9].

The masonry house utilizes 42.5 cm thick load-bearing vertically perforated insulating brick walls protected against moisture and frost through interior and exterior render layers (see Figure 5) [10]. Compared to conventional brick construction employing EPS filling, the monolithic masonry assembly offers improved recyclability while its high thermal mass maintains climatic inertia [11].

The lightweight concrete house employs 50 cm thick infra-lightweight concrete walls containing expanded glass secondary aggregate for insulation performance (see Figure 6) [12]. The high thermal storage mass of exposed infra-lightweight concrete eliminates the need for supplementary insulation layers or reinforcement [13].

For all three buildings, simulation modelling during the preliminary research process was used to ascertain optimal window proportions and room geometries standardized across the builds, eliminating the need for exterior sun protection while reducing operational energy demand [14]. Moderately sized punched windows within the thick monolithic walls reject the fully glazed curtain wall strategy common in contemporary construction, returning instead to a traditional and simple approach that achieves consistent thermal performance without thermal bridges [15]. Cold attic spaces and uninsulated sloped roofs further reduce costs and construction complexity while reinforcing the project’s embrace of low-tech simplicity [16].

technical sufficiency and circularity

Circularity within the project is mediated through durable, simplified material systems driven by sufficiency. Monolithic assembly and material purity improve future recyclability, selective deconstruction potential, and material recovery [17]. Technical systems are consistently separated from structural construction, allowing accessible maintenance and repairability (see Figure 7) [18]. Flexible floor structures and durable interior surfaces further support potential adaptation throughout the building lifecycle [19].

Identifying increasingly complex technical installations as a major contributor to rising construction costs, the project critiques the “performance gap” observable in technologically intensive buildings, wherein theoretical efficiency depends on ideal user operation and laboratory conditions compared to real-world performance [20]. In response, technical systems are approached through principles of low-technology robustness. Following construction, a network of over 300 sensors continuously monitored exterior walls, air temperature, humidity, radiation temperature, CO2 content, illuminance, and user behaviour throughout the first two years of occupation, in order to evaluate success of the “Building Simply” strategy through occupant comfort and environmental performance [21].

material strategies and data monitoring for passive environmental design

The project pursues occupant comfort and reduced carbon and energy consumption through passive material strategies rather than technological optimization. Thermal inertia in chosen materials, optimized window positioning, pitched roofs with external eaves and gutters, compact building forms, natural ventilation through operable windows and air exchange slots, and biogas radiator heating collectively regulate environmental performance (see Figure 8, Figure 9, Figure 10) [22]. In contrast to the performance gap often associated with high-tech systems, the simple buildings largely met expectations due to the predictability of material-based strategies [23]. User comfort surveys indicated generally high occupant satisfaction, with south-oriented and solid-timber dwellings receiving the most positive evaluations, illustrating the effects of both materiality and passive environmental strategies on perceived quality (Figure 11) [24]. Results ultimately indicate that robust construction using environmentally performant materials can achieve superior real-world performance and reduced lifecycle costs compared to technologically intensive “low-energy” buildings reliant upon active systems.

Monitoring studies demonstrated that the timber house achieved the lowest operational energy consumption, though its lighter construction showed a greater tendency toward summer overheating compared to the heavier masonry and lightweight concrete systems, necessitating additional sun protection on west-facing windows and resulting in slightly warmer perceived interior temperature [25]. The lightweight concrete house demonstrated the greatest summer comfort due to its high thermal inertia though was rated as “too cool” in winter, while the masonry house most effectively regulated indoor humidity [26].

material circularity through lifecycle analysis

Circularity was additionally evaluated through the Urban Mining Index lifecycle assessment. The timber house demonstrated the highest circularity potential due to renewable PEFC-certified wood and high reuse potential; lightweight concrete performed favourably due to the incorporation of secondary materials [27]. Lower recyclability was indicated for the masonry assembly due to its reliance on non-renewable raw materials, though the vertically perforated system improved material recovery potential compared to conventional insulated masonry construction [28].

thermal transmittance and energy performance

Monolithic wall assemblies aim to achieve consistent performance without thermal bridges. The timber house achieved the strongest measured wall performance with a U-value of 0.22 W/m²K, while the lightweight concrete house achieved 0.32 W/m²K and the masonry house performed significantly worse than expected at 0.40 W/m²K (see Figure 12) [29]. Although these values generally satisfy milder European climatic requirements, the concrete and masonry assemblies substantially exceed many Canadian wall performance requirements, where maximum U-values commonly fall between approximately 0.18 and 0.28 W/m²K depending on climate (see Figure 13) [30]. As such, direct implementation of the Einfach Bauen model within colder Canadian climates would likely necessitate increased wall thicknesses, supplemental insulation strategies, or adaptation of the monolithic envelope concept.

Despite thermal transmittance limitations in colder climates, the project demonstrates strong environmental performance and occupant comfort through simplified construction strategies that reduce lifecycle complexity, technical dependence, and material consumption. The research has subsequently informed multiple follow-up projects by Florian Nagler Architekten, including the Wogeno cooperative housing project, House 4 research building, and the Garden House in Munich, which further develop monolithic bio-based construction and adaptable low-tech environmental strategies [31, 32] . Collectively, the Research Houses Bad Aibling position simplicity, material sufficiency, and robust passive architecture as viable circular strategies for adaptable and resource-efficient housing.

references

ArchDaily. 2021. “Research Houses Bad Aibling / Florian Nagler Architekten.” April 20. https://www.archdaily.com/960283/research-houses-bad-aibling-florian-nagler-architekten.

BAU München. n.d. “Simple Construction—a Worthwhile Path?” Accessed May 14, 2026. https://bau-muenchen.com/en/bau-insights/detail/simple-construction-a-model-for-success.html.

Cooperative Housing near Rosenheim. 2024. Summer 2024.

“Einfach Bauen – A new paradigm of timber construction based on Sufficiency.” 2024. Madera Estructural / Structural Timber, October 21, 2024. https://maderaestructural.wordpress.com/2024/10/21/einfach-bauen-a-new-paradigm-of-timber-construction-based-on-sufficiency/.

“Energy Code Requirements: Canada.” n.d. Steelway Building Systems. https://steelway.com/wp-content/uploads/Energy-Code-Requirements-Canada-SBS.11.22.pdf.

Isopp, Anne. 2023. “Serial Building Systems from Wood.” DETAIL Magazine, June 2023.

Jungblut, Sarah-Indra. 2023. “Achieving More With Less By Building Simply.” Digital for Good | RESET.ORG, September 18, 2023. https://en.reset.org/simple-building-low-tech-construction-approach/.

Kaltenbach, Frank. 2022. “Building Affordably? Building Simply! Interview Florian Nagler.” DETAIL Magazine, June 2022. https://inspiration.detail.de/en/article/building-affordably-building-simply-interview-florian-nagler-5942.

Swedish Wood. 2024. “Housing with a Focus on Simplicity and Socialising.” Swedish Wood, March 14. https://www.swedishwood.com/about_us/news/2024/3/housing-with-a-focus-on-simplicity-and-socialising/.