Integrating Building Information Modeling for Thermal Transfer Value Calculation in a Conceptual Design Stage

Abstract

In many southeast tropical countries of Asia, overall thermal transfer value (OTTV) and roof thermal transfer value (RTTV) are standard thermal performance measurements for code compliance. They are designed to evaluate a building envelope design on reference to external heat gain. The objective of this thesis is to develop an OTTV and RTTV calculation framework during the conceptual design stage using building information modeling (BIM) and visual programming language (VPL). This research methodology included five main stages. First, a commercial building case study was set based on Thailand building energy code (BEC) 2009. Second, a BIM 3D model was developed as a base case design scenario using Revit, including the materials thermal properties. Third, VPL scripts utilizing Dynamo software were used to create a BIM OTTV and RTTV calculation model framework. Through VPL scripts, a BIM OTTV and RTTV calculation model was created and connected to the 3D BIM model, while the utilizing of Revit application programming interface (API) automatically extracts and retrieve BIM information. Fourth, the BIM OTTV and RTTV calculation model were tested with different design scenarios in the conceptual design stage. Finally, the results of the BIM OTTV and RTTV calculation model were verified using Thailand BEC software. The domains for verification included different design scenarios for commercial, office, and residential buildings. The model was tested with different design scenarios and was verified with Thailand BEC software. The findings revealed that the model’s results were slightly different from ones calculated by Thailand BEC software. The difference of the OTTV calculation of commercial buildings ranged from 0.06% to 0.68 %, whereas the difference of the RTTV calculation was 3.07%. In terms of office buildings, the OTTV calculation difference ranged from 3.06% to 4.06%, while the RTTV calculation difference was 11.07%. For residential buildings, the differences of OTTV and RTTV calculation between tested models and Thailand BEC software were 1.08%-1.38 % and 3.82%, respectively. The methodology proposed in this study showed that using BIM, couple with VPL, in OTTV and RTTV calculation during the conceptual design stage may be implemented automatically. When compared to the building energy code results, the developed model was accurate, with an acceptable difference in OTTV and RTTV values. Using a BIM OTTV and RTTV calculation model during the conceptual design stage can assist building design professionals, in a timely way, on a decision-making process, that can include materials, sizes, colors, shapes, forms, and fenestration ratios that meet the OTTV and RTTV requirements of the building energy code.