M.Sc. Thesis

A CAD System for Design and Evaluation of Solar Apartment Buildings, 1991

A considerable part of the architect’s effort during the initial schematic stages of the design process focuses on the determination of the geometry of the building. The present study deals with the creation of a design tool to help through all the stages of the design of an apartment building, particularly during the early conceptual phase, when the geometry of the building and its solar features are determined.

A detailed definition of all the building’s input is essential for running a simulation model for the correct and accurate evaluation of design solutions. During the first steps of the design the architect obviously deals with defining the geometric aspects of the building, without having any data about other parameters, such as color or envelope insulation which he will attend to at a later stage. Consequently, the architect designing an energy-conscious building must resort to simple rules of thumb or to approximate calculations which might lead him to wrong conclusions. Using more accurate hourly simulation based systems is deferred to the detailed design stages, after all the information and building details have been completed, when any attempt to revise the original design is hard and costly.

The proposed system combines the use of specific heuristic rules which are the knowledge base of the system, with the use of an accurate hourly simulation model to determine the value of the various design parameters in the process of designing an apartment building. The system identifies which parameters can be determined by applying the heuristic rules, and which, owing to their sensitivity to value changes of other parameters, must be determined by means of an examination by a simulation model. Subsequently, some design parameters are determined by defaults. As a result less data must be defined by the architect, so that the use of accurate CAD tools is made possible during the schematic-conceptual design stages as well, thereby ensuring a better design of an energy-conscious apartment building.

The study consists of three main parts:

  1. Classification of design parameters, development of heuristic rules and their integration into the computerized system.
  2. Development of an energy evaluation model of an apartment building.
  3. Demonstration of the application of the system to design a single unit and a whole building.

The first part of the study deals with the examination of the different design parameters so as to determine their effect on the energy consumption and the thermal behavior of the building, as well as their classification into groups to be specifically dealt with the system. These examinations were carried out by numerous runnings of the simulation model on pre-defined prototypical buildings. The results of these examinations constitute the basis for the development of the heuristic rules to determine the design parameter value. These rules were integrated into the computerized system, and the procedures corresponding to the system’s processing levels for each design parameters to determine its recommended value were presented. These procedures can be utilized to design by the computerized system based on heuristic rules, to advice the designer, to criticize the architect’s proposed solution, and to evaluate the design based on the simulation model. In the second part of the study, a model for the energetic evaluation of an apartment building was developed, to help the designer determine the preferred building configuration so as to obtain a more efficient solar apartment building. The last part of the study demonstrates how to apply the system to design a single unit and a whole building.

The model proposed in this study enables the use of accurate evaluation tools intended for the detailed design stage during the earlier schematic-conceptual stage, thereby ensuring an efficient, correct initial design as far as energy is concerned. Finding an effective solution in the initial stage is the key to success in designing passive solar buildings. This is why the proposed CAD is an efficient and useful tool for a computerized energy-conscious architectural design.

© Copyright 1991by I. G. Capeluto