English

Air supply diffusers used in air-conditioning systems can be classified as ceiling diffusers, sidewall diffusers, floor diffusers, jet nozzles, and low velocity displacement diffusers. Fixed or adjustable slats are usually used to control airflow directions.

With the advancement of technology, and with the widespread availability of simulation tools, we are forced to consider which simulation tool would be appropriate for a particular problem. The seemingly trivial decision is in reality not very easy to make. And this leads to the practice of using the most sophisticated tool available for every problem. The levels of resolution and complexity are directly related to the accuracy of the simulation and to the total cost of the simulation process. A simple tool may be cheaper, but there is a high risk of inaccuracy.

This paper will address the shortcomings of typical heat balance-based HVAC design and analysis software when applied to thermal displacement ventilation (TDV) system design. The performance characteristics of thermal displacement systems that lead to inaccurate calculations from heat balancebased programs are discussed. Finally, the paper presents an approach for estimating the performance of TDV systems using existing heat-based calculation tools that responds to most of the significant differences between overhead mixing systems and thermal displacement systems.

This paper presents the development of a simulation tool based on the Matlab computational environment for building temperature performance analysis with automatic control. The simulation tool contains mathematical models for buildings, HVAC (Heating, Ventilation and Air Conditioning) systems, sensors, weather data and control algorithms. The building mathematical model is described in terms of statespace variables, with a lumped approach for the room air governing equations energy and mass balances. In this context, the simulation tool structure and components are explained.

This paper describes a performance-based evolution model using Genetic Algorith as the evolution algorithm and CFD as the evaluation mechanism. The advantages of such an evolutionary performance-based design approach is that diverse instances of the state space can be investigated in relation to specific goal requirements that will enhance the possibility of discovering a variety of potential solutions. The model allows the user to explore and visualize the design evolution and its form generation in an attempt to stimulate the designer creativity that might contribute to their output.

A comfortable indoor climate environment is necessary for modern buildings and therefore the Heating, Ventilation and Air-Conditioning (HVAC) systems are widely used. Faults or disturbances are normally unavoidable in the systems and they will lead to more energy consumption or degradation of comfort level of indoor climate. Energy consumption is useful to detect the

The practical use of building simulation software requires a global and comprehensible interpretation of results for decision support in design. We propose a method in which the temperature of the free-running building is used to express: 1) the ratio between energy consumption for heating and cooling, 2) energy saved when ventilation is used instead of mechanical cooling, and 3) the degree of building adaptation to the environment.

This article defines a new air-exchange efficiency that takes into account the occupancy in each zone.. Cases studies are then described and show that the new efficiency can better evaluate the ventilation effect of the room.

A questionnaire study (on ventilation, surface materials, heating and cooling) was performed on 3562 employees working in 32 buildings without previously known indoor air problems.The associations between symptom prevalence and building characteristics are reported in this paper.

The aim of the study is to validate CFD approaches for the simulation of the dispersion of gases and vapors in an enclosed space at different flow rates, and to show the impact of one important determinant of simulation accuracy.CFD results and measurements were compared, showing a good correspondance for the pollutant concentration when the boundary condition was a profiled velocity inlet and not an uniform velocity inlet.