Building information modeling (BIM) and parametric modeling are very current themes in today’s AEC industry. Instead of drawing lines, parametric building models are defined by rules and constraints, which identify aspects of the building - from physical characteristics to environmental parameters - and their relationships to each other. Creating and modifying these parameters, or the relationships between them, is an important part of the design process. Changing a rule or constraint, or modifying a part of the model itself, almost always has implications on the entire model. In other words, the parametric model functions a bit like a spreadsheet: changing a feature of the building is like changing an entry of the spreadsheet. In response to a change, the software regenerates the model so that pre-determined relationships are maintained, just like a spreadsheet re-calculates all of its entries. This makes parametric building models extremely powerful design tools, facilitating the design and construction of buildings which would have been impossible only a few decades ago.
Take, for example, The London City Hall, shown at right. This iconic building designed by Norman Foster, houses the Mayor of London, the London Assembly and the Greater London Authority. The use of glass and a giant helical staircase in the interior are supposed to symbolize the transparency and the accessibility of the democratic process. What is most striking when looking from the outside, though, is the building's odd shape.
Perched on the banks of the river Thames, the building is reminiscent of a river pebble. The spherical shape was chosen not only for its unique look, but also to maximize energy efficiency by minimizing the total exposure of the façade to solar radiation. The building's lopsidedness is also conducive to energy efficiency: the overhang on the South side ensures that windows here are shaded by the floor above, thus reducing the need for cooling in the summer. During the design phase, computer modeling showed how air currents move through the building and the geometry within the building was chosen to maximize natural ventilation. In fact, the building does not require any cooling at all and reportedly uses only a quarter of the energy of comparable office spaces.
The Parametric City
The idea that we can generate an ideal city from a set of principles and logical steps has of course tempted city designers since long before computers were invented. Masterplans are large, they take a long time to develop, they are expensive, they require a wide consensus, and, most importantly, the design process needs to keep track of a huge quantity of complex information. For this reason, a systematic, rather than intuitive, design approach is needed. Computers, along with generative parametric techniques make it easier than ever before to make this idea a reality.
Parametric urban design is a new design discipline that utilizes elements of both urban planning and architectural design. It promises to radically update urban design, real estate development and master planning, in the same way that Building Information Modeling (BIM) and software like Revit and ArchiCad have transformed the architecture industry.
Adopters of the parametric planning process are able to make design decisions based on objective data built into an urban 3D model. A key component of this new technology is the automatic measurement of sustainability and livability factors, and the ability to address such issues as:
Activity throughout the 24 hour cycle
Land/building use mix
Number of dwellings within 5 minutes walk of any site amenity (example: a bus stop)
Average distance from every dwelling to green space
On-site Energy use and/or production
Green space per person
Total parking spaces
Parametric city models are extremely powerful - if you make a change to the spatial design, all information is updated immediately, allowing the implications of design changes to be understood immediately as well. For example, you could change the mix of ‘affordable’ and ‘market’ housing, adjust the street layout, or add storey’s to a building, and then instantly see the impact on the viability of the plan.
Parametric design tools can also help assess the sustainability performance of tomorrow’s ‘green’ city. Different assumptions about energy, water use, movement, waste management and CO2 can be plugged in, and the environmental footprint will be instantly recalculated as the design model is changed.
Modelur is a revolutionary new parametric urban design tool seamlessly integrated into Google SketchUp. It offers basic tools for quick and effective urban design. In contrast to traditional CAD tools, where the building is described by its width, length and height, Modelur uses a parametric approach, in which the building can also be designed by a combination of desired final parameters, e.g. built area, gross floor area or number of storeys. When one of the basic parameters is changed, all buildings get updated and urban control values are recalculated.
Different colors represent a number of land uses, with models including residential, service, industrial and mixed use. The software automatically detects planning conflicts, notifying the user if buildings are too close or a built area is overused. An on-screen display provides a list of current urban control values.
Modelur supports terrain import or 3D export with Google Earth. Users can create sun illumination simulations and save the file as a movie. SketchUp models, such as the Heritage Street Clock by Canterbury Designs, shown right and available as a free download from CADetails.com, can also be added to the setting.
To learn more, visit the Modelur website or the Modelur YouTube channel. Modelur is currently still in pre-beta testing program, in which all interested in getting first hand experience are able to use the application at no charge. If you want to test drive Modelur fill out the form on the Modelur website.