How CMU gets its groove back: improving the performance of concrete masonry units through adaptable self-shading

Energy and aesthetic performance are often at odds in design and construction. Energy performance,
commonly led by an instrumental logic, gives little room for a more extensive cultural influence outside
efficiency. From its technological inception, Concrete Masonry Units (CMU) have maintained a parallel
history of industrial production and aesthetics goals and are conducive to research, such as this proposal,
which aims to create a thermally performative material aesthetic. In early concrete block construction,
textured blocks mimicking stone or naturalistic motifs were the only few alternatives to flat faced units
whose exterior surface matched their construction means. Later, early modern experiments in related
block construction, such as Frank Lloyd Wright's textile block works, moved away from the mimicry of
earlier construction techniques and naturalistic imagery toward a greater degree of abstract patterning.
Patterning, inherent in masonry's bonding logics, developed during modernism to be the defining
aesthetic characteristic of CMU. Porous breeze block and highly textured block faces used patterns both
within and between concrete masonry units to create rich surface textures that visually explore light and
shadow dynamics. CMU in modernist construction forefronted industrial serialization as an aesthetic asset
and showcased an early engagement of concrete block construction with environmental performance
through ventilation and (shelf)shading. The most recent digital experiments with masonry tend to focus
upon the systemic organization of blocks through robotics and CNC technology, techniques that are not
economically effective in the majority of market-rate construction.

Today, CMU most often operates aesthetically in the modernist paradigm of serialization or via an early
20th-century mimicry of stone. Neither of these productively addresses the issues related to the built

environment's carbon footprint, energy-efficiency in buildings, and computational design, which dominate
much of the contemporary architecture and construction discourse.
This research proposal engages such issues using a cross-disciplinary approach that bridges different
knowledge fields, including building physics, building performance simulation, optimization, and digital
fabrication. The main target is to combine advanced thermal and whole-building energy simulation,
optimization, and adaptable construction techniques to develop new thermally improved CMU blocks.
The project engages the surface aesthetic of CMU in an aperiodic and localized manner to improve
exterior walls' thermal performance composed of exposed CMU blocks. The investigation examines the
benefits of shading the opaque surfaces of building envelopes by embedding grooving patterns that
promote CMU blocks' self-shading in building façades. Liu et al. (2019) demonstrated that shading the
non-transparent portion of façades reduces building cooling loads and consequently the heat island effect
in highly dense urban areas. Despite the promising results of Liu et al. (2019), the study did not perform a
comprehensive optimization of different shading profile angles and only considered one location, Hong
Kong, where shading is less effective because overcast skies diffuse radiation predominance. Thus, the
research team believes there is space to improve and propose solutions whose energy-saving potential
goes beyond the literature results, particularly in warm to hot climates dominated by clear skies.
Standard running bond wall assembly organization will be used for simplicity of study and maintain a clear
path for future application. The research will focus on optimizing CMU blocks' heat rejection potential
through small scale self-shading grooves cast into the CMU face and within assembly logics common to
masonry construction. The design procedure combines algorithmic/parametric modeling tools, advanced
whole-building energy simulation software, and evolutionary optimization algorithms into a single
performance-based generative design system (PGDS) (Santos, 2020). The parametric/algorithmic
modeling tools allow the generation of different shading groove patterns. The building energy simulation
software estimates their thermal behavior. Finally, the optimization algorithm automatically searches for
pattern designs that minimize building cooling loads. This sophisticated approach allows designers to
understand better the impact of different shading strategies on the complex transient heat transfer
phenomenon that depends on the interplay between thermal resistance, storage, and solar heat gain.
The research then discusses inexpensive fabrication methods to physically test, calibrate, and validate
the optimization of the shading groove patterns. The research team proposes developing an inexpensive
fabrication method of embedding different form liners into CMU blocks. Such fabrication methods should
be easily transferable to industrial production scales and handle the deployment of different block patterns
designed for thermal optimization across buildings of multiple scales.

New co-simulation methods for micro self-shading of building units
Custom made fabrication methods of concrete masonry units