TSINGHUA SCIENCE AND TECHNOLOGY I S S N 1 0 0 7 - 0 2 1 4 0 8 / 1 8 p p 3 2 7 - 3 3 2 V o l u m e 14, N u m b e r 3 , June 2009

Plausibility in Early Stages of Architectural Design: A New Tool for High-Rise Residential Buildings

Dirk Donath, Danny Lobos**

Chair of Computer Science in Architecture, Faculty of Architecture,

Bauhaus-University, Weimar 99423, Germany

Abstract: This paper analyzes the problem of the design of envelopes for high-rise isolated residential build-

ings. The phenomenon of envelope creation appears in the early stages of the architectural design. Vari-

ables that influence the final shape and size of such envelopes are then identified. This paper presents the

state-of-the-art tools for the current solutions at the commercial and academic/scientific level. The variables

identified in this research are the client's needs, the urban code and architectural practice, and their specific

components for the final creation of a new decision support system tool based on the building information

modeling (BIM) software platform, to facilitate the work in the project development and drawing production

stages. This tool generates several options for building envelopes according to the parameters required by

the city Zoning Planning Commission. These options then lead to deliver reliable data and a geometry that

can be analyzed in a timely fashion by the engineers, builders, architects, government, and clients in the

early stages of the building's design. The results show that use of specific information and communication

technologies (ICT) tools in the early stages of a building design helps reduce the working time, increases

confidence in the generated solution, and contributes to the exploration of alternatives in a short period of

time.

Key words: constraint based design; parametric programming; urban modeling; optimization; architectural

design

Introduction

In the early stages of the architectural design of a high-rise residential building, the architects must design a theoretical volume as a visual reference for the "de-fault" zoning planning and building codes for the plot. Later, they can design a different volume that fulfills the more "specific" building codes, but also satisfies their own practice and the client needs. Finding the op-timum volume in a reasonable time is a complex task.

Received: 2008-03-28; revised: 2008-11-16

* * To whom correspondence should be addressed.

E-mail: danny.lobos@architektur.uni-weimar.de

Tel: 49-3643-584210

The design is based on a "variety of possible shapes and sizes for the building envelope versus one theo-retical volume in a plot". The key variables are related to the client's needs (space program), the zoning plan-ning regulations (urban codes), and the architectural practices (in current development). This paper presents a solution for the space program and the urban codes.

This research analyzes the building from a norma-tive point of view [ 1 ], but also includes variables related to the client and the architect, who normally have an influence on the final shape and size of the building envelope.

The initial and schematic definition of the shape and size of the building envelope is included in the urban regulations of most countries' building codes, and is

328 Tsinghua Science and Technology, June 2009, 14(3): 327-332

well-known as the "maximum building wrap/bulk" or "theoretical volume" that is a tridimensional volume, similar to a six-sided polyhedron with additions or sub-tractions based on the building codes. These initial plans are normally submitted as part of the file for the government building permit.

1 Research Objectives

The main objective is to determine and quantify the factors that influence the shape and size of the final building envelope of an isolated high-rise residential building to establish the relationships between the cli-ent's needs, the building code requirements, and the architectural practice in the early stages and to synthe-size these relationships in a new digital tool to support the creation of an optimized, parametric building enve-lope in a plot.

2 Urban Codes: History and Present

The origin of the use of theoretical volumes is linked to the existence of urban planning, particularly to ur-ban regulations since the Athens Charter in 1933 and the Seagram Building designed by Ludwig Mies van der Rohe and Philip Johnson in 1958.

The New York City 1916 Zoning Resolution was adopted primarily to stop massive buildings such as the Equitable Building in New York for preventing light and air from reaching the streets below. Figure la shows the zoning and excess bulk limit. The resolution established limits on building masses at certain heights, usually interpreted as a series of setbacks, and while not imposing height limits, restricted towers to a per-centage of the lot size. Figure lb shows some buildings designed under these concepts. Architectural delineator Hugh Ferriss popularized these new regulations in 1922 through a series of mass studies, clearly depicting the possible forms and how to maximize building vol-umes. The new 1961 Zoning Resolution coordinated use and bulk regulations.

The variation of the theoretical volume in the inter-national context will be analyzed for four cases with a brief description of the most common norms and regulations.

United States Historically speaking, the United States has the best known urban regulations due to buildings designed by famous architects whose shapes

were determined from the application of the codes, es-pecially in New York City, where the first American Zoning Law in 1916 (called "New York City 1916 Zoning Resolution") was written, as described by Dolkart[ 2 ]. Many buildings were designed using these new concepts and the new 1961 Zoning Resolution. The main variables to be considered are setbacks, cov-erage area, open area, built area, floor to plot area, and the plot area ratio.

(a) Equitable Building, New York

(b) Some buildings using setbacks

Fig. 1 Examples of urban planning

Germany The main variables to be considered in Germany are minimum distances, rules for different roof forms, surface area index, floor space index, building lines, building borders and public surfaces, and fire protection regulations.

Chile The main constraints in Chile include use, grouping mode, buildable coefficient (built area), site coverage coefficient, setback requirements, sky expo-sure plane, building height, story height, parking, un-derground levels, shadows, and combination of plots.

Argentina The main variables to be considered in layout include the plot area ratio, coverage area, set-backs, and sky exposure plane.

Dirk Donath et al: Plausibility in Early Stages of Architectural Design . 329

The current implementation considers the following zoning planning regulations: site size, buildable coeffi-cient (plot area ratio), site coverage coefficient (cover-age area), setback requirements, sky exposure plane, maximum building height, story height, and under-ground levels (height and total depth).

3 Early Stages of the Architectural Design Process

The research is focused on the early stages of the ar-chitectural design process. This stage includes analysis of the theoretical volume and the final building enve-lope. The decisions made in this stage are irreversible; therefore, they are the most important. Some ap-proaches to the definitions and tasks of these early stages were discussed by Lewis [ 3 ] and Lyon [ 4 ]. This work is based on the International Building Code (IBC), in which Patten [ 5 ] indicates that the first step of all of the services provided by an architect/engineering office is called the schematic design phase (15% of the total services), in which the following are considered: programming, space diagrams, site development plan-ning, site utilization studies, utility studies, environ-mental studies, and zoning.

4 Variables

4.1 Variable 1: Space program

The space program is a transcription or translation of

the needs of the client into an architectural program-

matic language, or words and figures that can be inter-

preted by the architect in terms of rooms, sizes, and re-

lationships. The spaces and their sizes (areas) must be

named, listed, and grouped by zones. A digital database

represented by a dynamic shared table is used to store,

edit, and quickly exchange the required building data [ 1 ].

4.2 Variable 2: Urban code

More than 10 rules apply at the same time in the early stages of the architectural design of a high-rise residen-tial building. These rules come from three main sources: building codes (for the country), local ordi-nances (commune or district), and the site information report (for the plot). Many different shapes can be de-rived with consideration of these rules starting from the "maximum theoretical volume". These definitions

are as follows: • Buildable coefficient (built area or plot area

ratio (PAR)) is a non-negative real value that, when multiplied by the total area of the plot, de-termines the maximum gross floor area (square meters) of the completed building (typical values are 1 to 10, increasing by tenths, e.g., 1.1, 1.2), regardless of its shape.

• Site coverage coefficient is a non-negative real value that, when multiplied by the total site area, determines the maximum floor area of the ground level of the building. The value ranges in tenths between 0 and 1 (e.g., 0.1, 0.5, 0.6) or percent-ages (e.g., 10%, 50%, 60%).

• Setback requirements determine the minimum horizontal distance allowed between each lot line of the plot and the nearest point of the building (in meters). The codes for this requirement differ depending on the country and are often related to the height of the building. The rule applies to dif-ferent parts of the building height.

• Sky exposure plane is an imaginary plane that cuts the theoretical volume. It starts from each lot line following a defined angle upwards towards the inside of the site (possible values are 60°, 70°, 80°).

• Building height determines the maximum verti-cal distance allowed between the natural ground level and the highest point on the building (in meters).

• Story height determines the minimum allowable vertical distance between the finished floor and the ceiling of an inhabitable room (the distance is 2.35 m in Chile).

• Parking for every building must be designed with the minimum quantity, determined by the lo-cal ordinance. In general, ordinances require 1 parking space per flat, with 10%) on the surface of the plot and the rest underground.

• Shadows from an isolated building can exceed the sky exposure plane if the shadow cast by the proposed building over adjacent plots does not exceed the shadow of the theoretical volume pro-jected over adjacent plots. This is not considered in this prototype.

Figure 2 shows a flowchart of these variables to ob-tain the building permission.

330 Tsinghua Science and Technology, June 2009, 14(3): 327-332

Fig. 2 Flowchart paperwork after rea

5 Computer Aided Architectural Design (CAAD) Prototype

5.1 Cadastre for existing commercial software

The results from Lobos[ 6 ] and his cadastre for the existing commercial architectural tools will be used here. The analysis tools were grouped into three areas: (1) Design software for architects: AutoCAD 2-D/3-D, Maya, FormZ, Sketchup, Maxxon Form, Rhinoceros, Paracloud, Ecotect, Generative Components, and Affinity R5.0; (2) BIM/AEC software: Revit Building, Archicad, MicroStation, Architectural Desktop, Allplan, Catia / Designer, Vectorworks; and (3) 3-D model and animation software: 3DSMAX, Cinema4D, Quest3D, Autodesk VIZ, Softimage.

There is presently no commercial application that resolves the problem completely. It is possible, and necessary, to develop new solutions for these new tasks by programming over the existing software or by creat-ing new solutions (plug-in or add-ons) in some pro-gramming language.

5.2 Cadastre for existing prototype software

The current state-of-the-art prototype tools for urban code tasks can be divided into two categories: those that work with several plots (urban planning for areas) and those that work with one plot (architectural design for a single plot). There are useful tools for both cases.

Recent research, mainly in Latin America, has sup-ported this process by creating some new information

ig full government building permission

and communication technologies (ICT) tools.

5.2.1 For several plots (1) CITYZOOM[ 7 ] is a decision support system for ur-ban planning, with a specific built-in city model, where data is represented in an object-oriented model repre-senting the urban structure to simulate the impact of al-ternative urban regulations for a large number of plots. Results can be displayed as tables and graphs and in a 3-D preview.

(2) In the project for Redevelopment of the Area Around the Main Station in Zurich, different software technologies were used for the visualization of the zon-ing planning regulations to support the design ideas.

(3) C-CODE 1.0[8] is an AutoCAD program for automatic generation of guided-style theoretical volumes and finished building envelopes for several blocks.

(4) NORMATIVA 3-D[ 9 ] evaluates the zoning plan-ning tools through tridimensional modeling with graphic representation of the target image or the urban shape for the city.

(5) CITY SIMULATOR™ simulates and analyzes cities where tall buildings with irregular shapes are emerging in pre-existing urban schemes.

5.2.2 For one plot (1) Building Code with the geographic information system (GIS) linked to the Internet has been described in several research papers

(2) Parametric Envelope[ 1 2 ] allows the creation of prototypes in Revit with the urban code being trans-ferred to computable data (input). The tool gives an

Dirk Donath et al: Plausibility in Early Stages of Architectural Design . 331

automatic theoretical volume output in real time. (3) Building Bulk Design Support (BDS) tool [ 1 3 ' 1 4 ] is

a constraint-based design strategy to support participa-tory residential planning processes. The tool synthe-sizes the boundary geometry from the volume, shape, and space allocation in the building and any part thereof located inside a given zoning lot.

(4) Spaceplan is for planning and optimizing build-ing regulations in urban plots. The input is the plot size, setbacks, plot area ratio, and maximum occupants. The output is the 3-D volume optimized by total area or to-tal stories.

(5) Simulador PRU_Datos was developed by SOL-NET-Chile S.A. for economic simulations and profit-ability analysis of plots in a district or commune.

Most of these prototypes are very useful tools sup-porting larger urban design/planning decisions or for working on a specific plot, but none considers as many codes as in this research.

5.3 Revit parametric model

Lobos[ 6 ] developed a tool called the "prototype for ur-ban code constraints". The model takes into considera-tion all the required variables for the design of the theoretical building volume using Autodesk Revit

Building because of its simple and powerful 3-D visu-alization capabilities and the possibility of adding parametric constraints to the 3-D Boolean operations through the use of the parametric families functional The prototype was implemented on Windows XP with an Intel Core Duo 1.66 GHz CPU and 1 GB of memory.

The total building area is calculated using the space program database (in Excel). Then, as shown in Fig. 3, several scenarios are plotted. The design starts with a generic box volume with constraints added that act as Boolean operators by subtracting mass from the origi-nal volume. The values of the codes (side plots, set-backs, sky exposure angle, maximum building height, underground depth, etc.) can be added by the architect in a text format in a user friendly interface where the changes in the shape and size of the volume in real time can be seen with about 1 min for each scenario. Then, the architect can automatically receive several reports on each scenario with 3-D views/floor/sec-tion/elevation plans, the total building area (m2), the building volume (m3), the area per story (m2), the perimeters (m), costs, open database connectivity (ODBC) databases, and industry foundation classes (IFC) models.

Fig. 3 Screenshot of "Prototype for Urban Code Constraints"

Further development must be considered that inte-grates the advanced programming interface (API) fea-tures into this prototype with the purpose of integrating the other detected variables. The Autodesk Revit API

can be fully accessed by any language compatible with the Microsoft .NET 2.0 (Visual Basic .NET or Visual C#). Following the reviewed literature and the cur-rently available software knowledge, the capabilities of

332 Tsinghua Science and Technology, June 2009, 14(3): 327-332

other languages for these complex tasks must also be considered, such as AutoLISP (AutoCAD/ADT), JAVA, Iconic Programming (Quest3D/Cinema4D), and Script (3DSMAX / Rhino / Generative Components).

6 Conclusions

Various tools are available for the design of the final envelope (shape and size) as opposed to the initial theoretical volume. These variables were synthesized into a tool that generates new optimized building enve-lopes for a site. The results show that use of specific ICT tools in the early stages of a building design helps reduce the working time, increases confidence in the generated solution, and contributes to the exploration of alternatives in a short period of time.

A new concept is proposed, the plausible optimal envelope, which defines the optimal relationship be-tween the different variables at an early stage of the planning process based on the client's needs, the urban codes, and the architect. This method can be extended to other kinds of buildings such as for health, educa-tion, or commercial facilities. The chance to use IFC codes in each stage must be mentioned as it helps to exchange information between all the software plat-forms and applications used in each stage and between all of the players involved in the building process. The constructors and engineers can receive information on the building in the very early stages of the design, ena-bling them to generate better designs.

References

[1] Lobos D. Plausible design of floor plans: A methodology

supported by information technology tools. In: Proceedings

of the 10th Iberoamerican Congress of Digital Graphics

(SigradiX). Santiago, Chile, 2006: 293-298. (in Spanish)

[2] Dolkart A S. The architecture and development of New

York City: The birth of the skyscraper. Columbia Univer-

sity, Digital Knowledge Ventures. http://nycarchitecture.

columbia.edu, 2007-07-01.

[3] Lewis R K. Architect?: A Candid Guide to the Profession.

Cambridge, Mass.: MIT Press, 1998.

[4] Lyon E. Strategies for IT adoption in the building industry.

Graduate Research Seminar, Georgia Institute of Technol-

ogy, 2002: 9-11.

[5] Guthrie J P. The Architect's Portable Handbook. First-Step

Rules of Thumb for Building Design. New York: McGraw-

Hill, 2003: 3-4.

[6] Lobos D. Plausibility in early stages of architectural design:

The case of theoretical volume in Santiago, Chile. Technical

Report for Research Theme, INFAR-Bauhaus-University

Weimar, Germany, 2007: 60-65.

[7] Grazziotin Ρ C, Benamy T, Sclovsky L, et al. Cityzoom—

A tool for the visualization of the impact of urban

regulations. In: Proceedings of the 8th Iberoamerican Con-

gress of Digital Graphics. Porte Alegre, Brasil, 2004:

216-220.

[8] Labarca Μ C, Culagovsky R R. C-Codel.0: Digital urban

simulation. In: Proceedings of the 2nd International Con-

gress City and Virtual Territory. Concepcion, Chile, 2005:

159-162. (in Spanish)

[9] Wurman R D. 3-D urban regulations—Three dimensional

modeling as a method for evaluation and generation of ur-

ban regulations [Dissertation]. Catholic University of Chile,

2006. (in Spanish)

[10] Raposo M, Sampio M, Raposo P, et al. A City Simulator.

New York: Acadia, 2001: 52-61.

[11] Frassia M. Digital urban code of the city of Buenos Aires.

In: Proceedings of the 3rd Iberoamerican Congress of Digi-

tal Graphics (Sigradilll). Montevideo, Uruguay, 1999: 209-

212. (in Spanish)

[12] Mellantoni G. Theoretical volume: Parametric modeling of

setbacks. Revit Workshop of the 10th Iberoamerican Con-

gress of Digital Graphics (SigradiX). Santiago, Chile,

2006-11-20. (in Spanish).

[13] Gonzalez L F. BDS: A building bulk design support tool.

INFAR Report, Bauhaus-Universitaet Weimar, Germany,

2005: 10-12.

[14] Donath D, Gonzalez L F. A constraint based building bulk

design support. In: Proceedings of the 10th Iberoamerican

Congress of Digital Graphics (SigradiX). Santiago, Chile,

2006: 278-282.