Modeling of Heat Transfer in Rooms in the Modelica "Buildings" Library

Abstract

This paper describes the implementation of the room heat transfer model in the free open-source Modelica "Buildings" library. The model can be used as a single room or to compose a multizone building model. We discuss how the model is decomposed into submodels for the individual heat transfer phenomena. We also discuss the main physical assumptions. The room model can be parameterized to use different modeling assumptions, leading to linear or non-linear differential algebraic systems of equations. We present numerical experiments that show how these assumptions affect computing time and accuracy for selected cases of the ANSI/ASHRAE Standard 140-2007 envelop validation tests.

An Algorithm to Translate Building Topology in Building Information Modeling into Object-Oriented Physical Modeling-Based Building Energy Modeling

“…The HeatTransfer and Room packages in the library are among the major models for thermal analysis of buildings, and have been validated by simulation results comparisons with benchmarked simulation models [36,37]. While the library is still under development and likely to be more extensively used through projects including IEA Annex 60 [38], which has the objective of developing and demonstrating new generation computational tools for building and community energy systems using Modelica [37], the use of it is still new and only a few demonstrated samples currently exist.…”

“…In addition, the class defines parameters for thermal simulations including convection, conduction, infrared radiation and solar radiation. Validation of the application using the MixedAir class has been conducted [22,36,37,39]. Table 1 shows the required parameters in creating an enclosed room with surfaces and constructions.…”

Validation and Application of the Room Model of the Modelica Buildings Library

“…Note that the current room model assumes that the air in the room is well-mixed so that a single volume is used to represent the room air. More details of the room model are available in [2].…”

“…These component models can be used for (1) rapid prototyping of innovative building systems, (2) design of building energy systems, (3) performance analysis of existing building systems, (4) development, specification and optimization of building control sequences, and (5) model-based operation for controls, fault detection and diagnostics. Recently, we implemented window and room models into the Buildings library to extend its capability to whole building energy simulation [2]. However, the models were not systematically validated against reference data in [2].…”

“…Recently, we implemented window and room models into the Buildings library to extend its capability to whole building energy simulation [2]. However, the models were not systematically validated against reference data in [2]. In [3], we presented the validation of the window model which is an important part of the room model.…”