BIM-based Automation for OTTV Calculation and Construction Cost Estimation in Energy-Efficient Building Design

Abstract

Due to the increasing trend of building energy consumption in Thailand, the Department of Alternative Energy Development and Efficiency (DEDE) established the Building Energy Code (BEC) to promote energy conservation. The BEC standard evaluates energy-efficient buildings with initial assessments conducted using the DEDE-developed software, BEC Version 1.0.6. The Overall Thermal Transfer Value (OTTV) is a crucial index in the BEC code for evaluating building energy efficiency. However, adding OTTV calculation task during the design stage may hinder the flow and time consuming. This study introduces a BIM-based tool developed using Dynamo, an add-in for Autodesk Revit, to assist designers in evaluating building designs while simultaneously controlling construction costs. The 3D model of eight alternative cases was created according to various building envelope and orientation settings. The instruction sets for OTTV calculation and construction cost of the wall extracted from the software were compared to the BEC program to validate its efficiency. The results demonstrate that the OTTV calculation using the developed instruction set closely aligns with the BEC program, achieving an R² value of 0.9898. Additionally, the instruction set for construction cost estimation produces lower costs compared to traditional methods. This workflow streamlines OTTV evaluation and construction cost estimation, enhancing design efficiency while ensuring compliance with energy standards.