USING BIM FOR BETTER FACADE DESIGN

Many architectural firms have embraced the use of Building Information Modeling (BIM) as a better, more coordinated, and more streamlined way to manage the design and construction (or renovation) of a building project. While the benefits of this approach are numerous, we will focus here on how integrated BIM software can greatly enhance facade designs as well by helping architects achieve a project’s optimal appearance and performance.

At the most basic level, BIM software allows architects to visualize how a project will look as well as perform against natural elements. The beauty of using BIM as a design tool is that professionals can quickly iterate different design options, wall assemblies, and material choices to compare the appearance of each and discern which is preferred. Similarly, the performance impact on the building and sustainability goals can be readily reviewed as needed to optimize outcomes. Integrated design tools aided by algorithms can help the design process with automation-enhanced testing of various scenarios. This integrated approach empowers designers to explore the aesthetic design features of a project with real-time rendering using a wide range of materials and textures resources. From a full facade planning standpoint, the software can also provide full visualization of sun paths and create sun studies as part of the design process. This can be invaluable in determining the degree of sun exposure and the appropriate means to address it, either for enhancing daylighting into a building or for shielding it from excessive solar gains.

Using data-driven design tools embedded in BIM objects helps architects make more fully informed design decisions. The data-driven design aspect of BIM software provides the opportunity to test the simulated or comparative performance of different design choices. This is possible because data from a BIM model generated with parametric building objects provides information to designers allowing them to make better design decisions. This can be most fully achieved by using BIM-generated automatic reports, quantity takeoff calculations, and schedules (i.e., room schedules, finish schedules, door and window schedules, etc.).

Colin Davis, of the London-based architectural practice Studio Partington, has been experiencing the benefits of using BIM for design for quite some time. It has helped him and the practice better understand the process of creating well-designed and truly sustainable buildings. He comments, “You don’t design a building that you like the look of and then strap on solar panels on the roof and build up the insulation really high and call it a day.” Using BIM, the firm is able to analyze and assess the data of different parts of the building envelope and readily compare different options to see what really does work and what doesn’t.

Davis also sees the larger value of using BIM for internal use as well as for explaining concepts to others. “I do think the ability to capture information graphically is a really great skill for architects to have,” says Davis, “and it’s often missing from research projects where the data might be great, but people haven’t really thought about how it is communicated.” It is here that Davis notes that the historic strength of BIM in graphics capabilities really shines for a mid-size firm like Studio Partington, where he notes, “Our job as architects ultimately is one of communication.” Part of that communication is in how a building will act or perform, too. “You can develop and test a massing model very quickly in BIM, which has many advantages, like using built-in tools for shadow analysis. So, [for example] the spaces you have labeled as ‘park’ if you see they don’t get much sunlight, you know immediately you must adjust the design.”

Image courtesy of Vectorworks

Vectorworks Embodied Carbon Calculator. Different types of facade material with relevant data can be analyzed within a BIM program to determine the optimal choice to reduce the building’s carbon footprint.

Image courtesy of Vectorworks

Sun shading systems can be analyzed within a BIM program to determine the most effective approach to reduce solar heat gain.

BIM and Carbon Emission Calculations

Part of designing more sustainable facades and buildings including an environmental or carbon assessment of the products, materials, and systems that are selected as part of the design.

Through the use of BIM software and other tools, data can be assigned to each component of the building based on published data from a manufacturer’s EPD. For instance, one can use material resources representing specific building materials to support an effective BIM workflow. These act as a receptacle for a wide range of information, like graphic attributes such as fill or texture, but also real-world physical attributes such as gravity, yield strength, tensile strength, density, embodied carbon, and other data that can be found in a product’s environmental product declaration (EPD). All this data within the material resource can be used to create accurate reports and data visualization diagrams. Each facade design can then be compared based on this data to more accurately determine global warming potential and embodied carbon values related to the materials used in each design scheme. This is ultimately most helpful in making informed decisions when evaluating different materials in a design and determining any required changes to reduce a building’s environmental impact.

The iterative design process based on its embodied carbon can be as simple as comparing the exterior wall system with various types of facade systems where the needed data has already been assigned to the materials in those facade types. When presented and compared, the data can ultimately speak for itself allowing designers to weigh in on the related pros and cons of cost, availability, or other factors. In this way, composite aluminum panels, for example, can be assessed as an alternative to more traditional materials like clay brick or even steel sheets. Some BIM software includes an integrated energy performance analysis tool which allows designers to assess energy performance in the early stages of the design (not needing to wait until later in the design process) and evaluate the building’s operational carbon right up front where it is easy to adjust the design as may be needed.

Relatedly, flexible design tools like BIM software support architects in their process of innovative thinking. It has been noted already that implementing sun shading systems is an effective practice for reducing solar heat gain and improving sustainable design. Customizing and automating the design of these systems can help to optimize a building’s energy consumption. Using tools based on algorithms-aided design (AAD), virtually endless opportunities are possible for design customization and analysis. For example, with algorithmic modeling, a designer can connect a sun shading element to real sun positions so that its orientation can respond to change throughout the day. This interaction allows for an accurate interpretation and analysis of sun shading studies focused on optimizing a facade design.

BIOPHILIC FACADES

Biophilic design is a design philosophy centered around connecting people with nature within built environments and communities. It has been applied to building interiors and exteriors and can be applied to building facades as well. There are a growing number of designs where the exterior wall is intentionally covered with living plant growth of various types providing a number of beneficial sustainability attributes. First, a “green wall” as it can be called, provides a natural means of shading a building from excess sunlight and heat, thus reducing cooling loads and the related energy use. Second, such a green facade can help to reduce the urban heat island (UHI) effect – a phenomenon observed when pavement, roofing, and other dark surfaces absorb sunlight and create islands of heated air in an urban environment. Green walls thus become an excellent alternative for building facades in urban developments. Third, green facades, particularly if used in conjunction with green roofs, can also assist with water management, absorbing and containing water, thus reducing potentially damaging stormwater runoff. Finally, green facades absorb carbon dioxide as part of the natural process of photosynthesis. This reduces the amount of carbon in the atmosphere and replaces it with plant-generated oxygen. Beyond the physical attributes, green facades, like other biophilic design techniques, have some positive health and wellness benefits too. Biophilia has been shown to promote calmness and boost creativity in different settings.

Images courtesy of Vectorworks

Modeled Green Wall Symbol. Different types of green wall systems with relevant material data can be analyzed within a BIM program to determine the best overall choice.