English

By describing three recent case-studies, this paper aims to elaborate the current state of building energy modelling and simulation in the Czech Republic in general, and at the Czech Technical University (CTU) in Prague in particular. The studies which are described were carried out at the Department of Environmental Engineering, Faculty of Mechanical Engineering, concern practical problems related to heating, ventilating, and airconditioning (HVAC) systems.

Thermal storage tanks are widely used in Japan mainly to shift electrical energy usage to night time for the purpose of peak demand reduction. However, the operation of the system has not often been accepted with satisfaction in a real field. Authors developed a method ensuring rational operation by utilizing predicted air-conditioning load based on an ARX model derived from building load simulation. The rational operation is achieved considering the predicted load and performance of HVAC components.

Hollow core ventilated slab systems provide an effective means of utilizing the building structure as a thermal store. The optimum control strategy for the system would be one that minimizes energy costs without prejudicing the occupant thermal comfort. This paper describes an implementation of one such strategy in which the optimum operation of the plant is predicted for the next day. The controller incorporates algorithms for predicting the ambient temperature and solar radiation over the next 24 hours.

An extensive experimental program on single sided natural ventilation was  carried  out  within the frame of PASCOOL EC research project. Within the frame of these activities, four single sided natural ventilation experiments were carried out in a test cell, a full scale outdoor  facility. Experimental data were used as  input  for numerical simulations that  were  carried  out using air flow calculation tools based on network modeling as well as computational fluid dynamics (CFD). Finally, fuzzy logic techniques were used to predict the air velocity profile in the middle of the opening.

This paper describes a series of tests that were performed to determine whether a neural-network model could outperform a correlation-based model in representing foundation heat losses. The two models were trained with data generated by BASECALC, a finite-element-based program for modelling foundation heat losses.

Modelling and simulation play a number of roles in engineering design studies. For Gaz de France, these studies must satisfy exacting criteria of quality and rapidity. Studies are even more effective if models developed on previous occasions can be stored and reused and if the company is able to share models with its partners. The development of model exchanges is therefore a key factor determining the future scope of modelling/simulation activities. The Modelica design group was set up to design of a new language for physical modelling.

General models for heat and mass transfer components have been developed for use in TRNSYS [1] thermal system simulations. These components remove some of the idealizations and detailed specifications that are required in existing TRNSYS component models. In these new component formulations, a set of parameters characterizing the performance of the component are fit using catalog data. This paper presents a technique for parameter estimation that can be used with realistic models to accurately represent equipment performance.

This is the second of two papers that describe the development of simulation methods for optimally controlled central plant equipment in IBLAST (Integrated Building Loads Analysis and System Thermodynamics). In Part II, the development and implementation of methods for simulating optimally controlled cold thermal storage in a building energy analysis program are described. The goal of optimising a thermal storage system is to minimise the daily energy cost of operating the system.

This is the first of two papers that describe the development of simulation methods for optimally controlled central plant equipment which have been implemented in the IBLAST (Integrated Building Loads Analysis and System Thermodynamics) building energy analysis program.

This paper is concerned with the optimisation of some design criteria for water based active solar space heating systems intended for residential applications in Cyprus.