Effective Facade Modularization

DRAFT PAPER SUMMARY CAPTURING KEY POINTS IN A BULLET POINT FORMAT - FULL CONTENT IN DEVELOPMENT

The modularization and unitization of facade systems is an effective strategy to create shop-fabricated facade solutions that benefit from improved quality of controlled shop environments, and allow for rapid installation on a project, limiting time spent on site. There are a number of additional parameters that should be reviewed as part of unitization strategies

What is being Unitized? There are several levels of what can be included in a shop-fabricated assembly, starting from:

1- Cladding Material(s)
1- Cladding Support Structure
1- Unit/Module Frame or Material

2- Waterproofing layer, which can be part of the cladding material when they are face sealed barrier materials and systems in lieu of rainscreen materials

3- Insulation

4- Interior Finish

5- Additional elements such as fins, small balconies

Facade Materials and Geometry:

- There are precedents of various materials being utilized in unitized and modularized solutions, this includes glass, metal panels, stone, terracotta, GFRC, UHPC, precast concrete, and timber. Certain finishes that are prone to damage or are brittle can be challenging to incorporate in the prefabrication facility as they risk damage during shipping and installation, and are frequently installed on site either on the ground before lifting the unit/module or in position. This includes elements such as fins made of terracotta, glass, and other materials. This decoupling however is also beneficial in shipping, as fin elements increase the shipping volume of the unit or module. IMAGES TO BE ADDED

- The depth of unitized and modularized systems varies based on spans, and the material used. The thinnest assemblies utilize ultra-high performance concrete, transitioning to steel-framed assemblies, to aluminum assemblies and lastly timber assemblies. The material properties in terms of tensile and compressive strengths follow this logic.

- When compared to traditional stick built assemblies, modularized systems can require a deeper overall assembly, this is partially due to the unit/module frame depth, but also due to the space required for bracketry and anchorage. Gaps are typically required between the facade and module when the system clads the entire envlope and does not only span floor to ceiling. These gaps are used for anchorage and to accommodate tolerances of the primary building structure that is being attached to. The anchorage methods need to be adjustable to compensate for such tolerances and align the position of the system to the true position. These gaps are typically filled with firesafing material to provide fire separation between levels.

- Transportation often dictates the effective size of a module or unit, as the facade needs to be transported from a fabrication facility to a jobsite for installation. Domestic transportation through trucking or railway is typically constrained to approximately 12' width utilizing an standard oversize permit that does not require complex logistics. While shipping via maritime transport is limited to shipping container widths which are approximately 7'-8". Given floor to floor heights are typically 10' or more, unitization commonly occurs utilizing the governing shipping width, and the length of the truck, train or container is used for height of the facade. When crating is taking into account, optimal widths are under 7' for containers and 11' for trucks. Where required, special permits and open-top containers, as well as ship hull storage can be utilized however at a much higher cost.

- The panelization geometry of a project can have an impact on the ability to unitize, standard rectilinear grids are most ideal, staggering between units can be achieved horizontally and also in some cases vertically with some modifications. However staggering within smaller panels that occur inside the unit are challenging. For example a facade with running bond stone panels would be challenging to unitize due to panels overhanging between two units, in some cases this can be achieved where those panels are field installed between units.

Embodied Carbon and Operational Carbon:

- Supply chain has a significant impact on A1 to A3 portions of Embodied Carbon, certain locations have cleaner energy grids which can improve the embodied carbon of a facade system. On the other hand, makes it worse if the grid relies on non-renewable sources and carbon-intensive energy generation.

- Supply chain also has a significant impact on the A4 Embodied Carbon calculation, depending on site location. Through a study that we have performed, transporting unitized facade components from the East Coast to the West Coast, on diesel-powered trucks or trains has a higher embodied carbon than marine freight from Asia or Europe, if the production facility is near a port or utilizes shipping on electric or clean-energy trains.

- Unitization can require additional framing material, particularly in cases where the erection engineering can be a driver in the frame design, additional framing means additional embodied carbon. The additional framing, particularly at the edges of each unit also impacts the thermal performance of a facade if it is creating thermal bridging in the insulation. This is commonly the case with aluminum framed curtainwalls, unless additional continuous insulation or mullion-wrap insulation is utilized. Whereas systems that do not include thermal insulation in the units may not have this impact however need to provide thermal insulation through other means and require them to be away from the facade which can also pose challenges.

Circularity:

- Unitized facade systems often have benefits in terms of circular economies and recycling of components, this is due to them being created from a kit of parts, where reversing the installation of that kit of parts allows for disassembly and use of the components on other applications. At the same time, unitized components can be taken taken off an existing building that will be demolished or requires a new facade, and reused on a different building.

- The UNESCO Building V in Paris by Bernand Zehrfuss and Jean Prouve is a remarkable precedent of a pioneering retrofit first, retaining and reusing as much of the existing facade as possible while preserving intricate detailing and extending the life of the building. The original facade had a modular approach, and was disassembled, cleaning and refinished and re-installed. The glass was sent to recycling facilities and the steel substructure was replaced with a timber structure which provided a resilient new structure that offered sequestration. IMAGES TO BE ADDED

Structural:

-UNDER DEVELOPMENT

- Seismic racking vs Seismic drift of units

- Stack joints, reduction of anchors

- Wind load restraints

- Thermal loads

- Impact loads

Installation Access:

- One of the key benefits of unitized and modularized approaches are the reduction of access needed for installation on the outside of the building. Traditional stick built approaches require full access from the exterior which often means scaffolding outside of the building to provide this access, this can be challenging and complex on high-rise buildings.

- Unitized approaches are also best suited on applications where the facade is at the outermost edge of the building and not obstructed by an overhang, as these systems are typically brought from above and lowered into position whether through a tower crane, or a smaller crane on the same level or level above. Facades that have balconies in front of them can pose challenges in installation or require added time.

- MORE INFO WILL BE ADDED.

Case study of Stone unitization, different options:

A case study project will be presented, where studies were performed on the potential untization and modularization of an opaque stone facade. Five different approaches were explored:

A1 - aluminum framed rainscreen - DESCRIPTION TO BE ADDED

A2 -Aluminum framed curtainwall - DESCRIPTION TO BE ADDED

B1 -Steel framed rainscreen/strongback - DESCRIPTION TO BE ADDED

B2- Steel framed megapanel - DESCRIPTION TO BE ADDED

C- UHPC Megapanel - DESCRIPTION TO BE ADDED

MORE INFORMATION AND ELABORATION ON THE OPTIONS WILL BE PROVIDED, SEE GRAPHICS.

CONCLUSIONS:

- Facades that have repeatability, orthogonal grids, facades at the outer edge, on large projects, and more than 5 levels are ideal for unitization.

- Facades that have irregular shapes, non-orthogonal grids, behind balconies, covered by overhangs, on small projects and less than 5 levels, are less ideal for unitization.

UNDER DEVELOPMENT, TO BE ADDED

UNDER DEVELOPMENT, TO BE ADDED