Abstract

Thermal load and indoor comfort level are two important building performance indicators, rapid predictions of which can help significantly reduce the computation time during design optimization. In this paper, a three-step approach is used to develop and evaluate prediction models. Firstly, the Latin Hypercube Sampling Method (LHSM) is used to generate a representative 19-dimensional design database and DesignBuilder is then used to obtain the thermal load and discomfort degree hours through simulation. Secondly, samples from the database are used to develop and validate seven prediction models, using data mining approaches including multilinear regression (MLR), chi-square automatic interaction detector (CHAID), exhaustive CHAID (ECHAID), back-propagation neural network (BPNN), radial basis function network (RBFN), classification and regression trees (CART), and support vector machines (SVM). It is found that the MLR and BPNN models outperform the others in the prediction of thermal load with average absolute error of less than 1.19%, and the BPNN model is the best at predicting discomfort degree hour with 0.62% average absolute error. Finally, two hybrid models—MLR (MLR + BPNN) and MLR-BPNN—are developed. The MLR-BPNN models are found to be the best prediction models, with average absolute error of 0.82% in thermal load and 0.59% in discomfort degree hour.

Highlights

  • Building design optimization involves the integration of an optimization algorithm with building performance calculation

  • Oftentimes the building performance calculation conducted by simulation software is time-consuming; the development of performance prediction models is a good alternative to significantly reduce the computation time

  • It is found that the relative errors for both thermal load and discomfort degree hour models using multilinear regression (MLR) algorithms are less than 10% with average errors of 1.2% and 0.9%, respectively

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Summary

Introduction

Building design optimization involves the integration of an optimization algorithm with building performance calculation. Olivieri et al [9] performed an experimental study to find the optimal insulation thickness of a vertical green wall under the continental Mediterranean climate and found an insulation thickness of 9 cm to be sufficient Building simulation software, such as TRNSYS [1], THERB [2], EnergyPlus [4], and New. HASP/ACLD-β [6] have been used to obtain the thermal load and/or indoor thermal comfort condition. Such programs require dynamic computing to calculate the hourly/subhourly thermal load and indoor comfort condition It becomes time-consuming when providing annual results, especially when coupled with an optimization algorithm and many iterations are inevitable in order to find the optimum building design solutions. Artificial neural network (ANN) models have been developed to predict the annual building energy consumption/thermal comfort condition to reduce the computation time during the optimization process [1,3,5]. Two hybrid models, called MLR (MLR + BPNN) and MLR-BPNN models, are developed to improve the prediction accuracy

Base Building Model
Independent Variables
Dependent Variables
Data Sampling Method
Single-Algorithm Models
Evaluation Method
Results and Discussion of Single-Algorithm Models
Method
Hybrid Model
Results and Discussion of the Hybrid Model
Conclusions
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