The set points of supervisory control strategy are optimized with respect to energy use and thermal comfort for existing HVAC systems. The set point values of zone temperatures, supply duct static pressure, and supply air temperature are the problem variables, while energy use and thermal comfort are the objective functions. The HVAC system model includes all the individual component models developed and validated against the monitored data of an existing VAV system.
Modelling of buildings with natural or hybrid ventilation systems requires the coupling of a thermal and an air flow model because of the strong mutual impact of the thermal and the air flow behaviour. The newly developed tool TRNFlow is the complete integration of the multizone air flow and pollutant transport model COMIS [Dorer 2001] into the thermal multizone building module of the building and system simulation program TRNSYS [Klein 2000].
This paper demonstrates an image-based lighting analysis procedure and tool called Virtual Lighting Laboratory. Virtual Lighting Laboratory is a computer environment, where the user has been provided with matrixes of illuminance and luminance values extracted from high dynamic range digital images. The discussions mainly refer to the flexibility of capabilities within a virtual laboratory environment to handle various lighting design and analysis problems.
From the view point of designing the energy efficient air conditioning system with maximized ventilation, the possibility of an all fresh air system was discussed using the simulation results of a model building in Tokyo. The algorithm of single duct cooling system for simulating the cooling coil of air handling unit based on the heat balance model of whole system components is also described as a base for the simulation of cooling effect of ventilation fresh air.
Considering the natural ventilation, the thermal behavior of buildings can be described by a linear time varying model. In this paper, we describe an implementation of model reduction of linear time varying systems. We show the consequences of the model reduction on computing time and accuracy. Finally, we compare experimental measures and simulation results using the initial model or the reduced model. The reduced model shows negligible difference in accuracy, and the computing time shortens.
The Transfer Function Method (TFM) is a tool able to solve heat transfer problems in building envelopes and environments and it is recommended by the American Society of Heating, Refrigerating and Air- Conditioning Engineers (ASHRAE). Authors have investigated TFM mathematical features, especially concerning the reliability and the quality of the thermal dynamic simulations. Using some basilar control systems tools like Bode plots, step response, model validation, results show clearly that, for a very massive building, a simply application of TFM very often fails.
While a lot of attention has been given in the study of indoor air distribution and its thermal performance, buildings clustered together in a development modify the outdoor environment to a great extent and the outdoor thermal performance of such a development is a critical factor for its success as to its acceptance by the tenants and visitors and their enjoyment of the outdoor activities.
The first energy efficiency law for Brazil was presented in 2001, which required that buildings should have some energy efficiency regulation. Salvador city building code was then submitted to a study to include energy efficiency parameters related to the building envelope. The energy consumption limits were associated with the envelope parameters using simulation and using a multi-variable regression equation developed using simulation.
Building simulation programs normally do not take into account moisture effects in soils temperature determination. However, the presence of humidity can strongly affect the temperature distribution in soils due especially to the evaporation/condensation mechanisms and the strong variation of their thermophysical properties.In order to calculate the temperature profiles in a more accurate way, we have developed the software Solum, which was conceived to model the coupled heat and moisture transfer in soils.
Building energy analysis are very sensitive to external convection heat transfer coefficients so that some researchers have made sensitivity calculations and proved that depending on the choice of convective heat transfer coefficient values, energy demands estimation values can vary from 20 to 40%. In this context, a Computational Fluid Dynamics (CFD) program has been used to predict external convective heat transfer coefficients at external building surfaces.