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No description available.

No description available.

In the present climate of energy conservation and CO2 emission consciousness, building heating, ventilating and air conditioning (HVAC) systems are required to achieve thermal comfort and indoor air quality in the most energy efficient manner possible. To this end optimising the use of natural ventilation is considered an area which can significantly reduce both the occupants discomfort and the energy consumption. The ability to effectively control the indoor environment would considerably enhance the use of natural ventilation. The overall aim of this research is to develop, commission and evaluate a fuzzy rule-based controller which can vary the resistance of ventilation opening in order to maintain an acceptable comfort conditions in the occupied space. The design of the fuzzy control system starts by establishing certain quantization levels for the input/output variables along with corresponding membership functions. Aspects of input and output variable choice together with their linguistic labels are explained and presented. Control rules are defined based on the off-line thermal modelling, experimental results and through discussions with experts. A dynamic air flow distribution is investigated through a series of experiments for different environmental conditions and opening levels without any control action. Three rule-bases of different complexity are developed and presented. All solutions are simulated in an input-output space and their differences presented in more detail through examples of the Mamdani inference method application. Controller validation is initially carried out using simulation as this offers the possibility of testing controllers under extreme conditions regardless of test room physical limitations. Simulations are carefully designed to allow simultaneous comparison of different controllers' performances. Then on-line validation is carried out in the test room by measuring the air flow distribution with and without the controller in action. A naturally ventilated test room and its instrumentation is set up. A controller commissioning methodology is established, involving the choice of software and hardware platforms and data acquisition methodology.

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The goal of this thesis was to improve the energy efficiency of building ventilation systems by exploring new methods of applying natural ventilation concepts. Strictly natural systems have limitations in which climates they can function or can provide optimal performance; these limitations lead to the use of mechanical or hybrid ventilation. This study looked at methods of combining the operation of the systems, such that the natural components improve the efficiency of the mechanical system.

This thesis explores the opportunities and limitations of steel construction and connection to the outdoors through a sports facility for the city of Blacksburg, Virginia. The program being that of an indoor soccer facility allows for the steel to express its ability to span great distances with a very fine and visually delicate structure. Cables express the steel's strength in tension. The structure is clearly expressed and easily understood by anyone who enters the facility. The building's indoor connection to the outdoor environment is achieved through the study and implementation of several strategies that not only enhance the visual and thermal comfort levels of those people in the facility but will also reduce the building's operating costs. One of the main strategies utilized to achieve this enhanced comfort level is that of natural ventilation. This will contribute to the overall air quality of the interior space and bring a refreshing breeze to the athletes and spectators of the facility. A second important design strategy is the utilization of natural light brought through and interacting with the translucent roof and steel structure. / Master of Architecture

Environmentally sensitive architecture is rapidly staking its claim on the building community. The structures that are being constructed to fulfill the increasing public demand for "green buildings" are not currently utilizing their unique potential to physically portray their inherent characteristics to be naturally and technologically advanced. Environmentally sensitive architecture has the potential and arguable responsibility to physically react to and portray the natural factors that they are programmatically and technically adapting to. / Master of Architecture

Energy usage in buildings has become a major topic of research in the past decade, driven by the increased cost of energy. Designing buildings to use less energy has become more important, and the ability to analyze buildings before construction can save money in design changes. Computational fluid dynamics (CFD) has been explored as a means of analyzing energy usage and thermal comfort in buildings. Existing research has been focused on simple buildings without much application to real buildings. The current study attempts to expand the research to entire buildings by modeling two existing buildings designed for energy efficient heating and cooling. The first is the Viipuri Municipal Library (Russia) and the second is the Margaret Esherick House (PA). The commercial code FLUENT is used to perform simulations to study the effect of varying atmospheric conditions and configurations of openings. Three heating simulations for the library showed only small difference in results with atmospheric condition or configuration changes. A colder atmospheric temperature led to colder temperatures in parts of the building. Moving the inlet only slightly changed the temperatures in parts of the building. The cooling simulations for the library had more drastic changes in the openings. All three cases showed the building cooled quickly, but the velocity in the building was above recommended ranges given by ASHRAE Standard 55. Two cooling simulations on the Esherick house differed only by the addition of a solar heat load. The case with the solar heat load showed slightly higher temperatures and less mixing within the house. The final simulation modeled a fire in two fireplaces in the house and showed stratified air with large temperature gradients. / Master of Science

In this thesis the air infiltration through the envelope of a naturally ventilated stone church located in Bergby (Gävle, Sweden) is studied. The project is focused on Multiple Linear Regression (MLR) modeling the air change rate (ACH) inside the church hall and studying the factors (stack effect and wind effect) that influence the air infiltration. The weather parameters outside the building were recorded in a weather station and the properties of the air inside the church was analyzed with different methods. Infrared thermography techniques and thermistors were used to measure the temperature inside, the tracer gas method to measure the ACH and the blower door technique to measure the tightness of the building envelope. In order to know the pressure coefficients on the church envelope a physical model of the building was studied in a wind tunnel. Firstly, only the values obtained from the weather station were used to calculate the predictors of ACH and see which parameter influence more on its variation:  temperature difference (∆T) indicating the stack effect; and wind speed (WS), the component of wind speed perpendicular to the long-side facades of the church (WS90) and their square values (WS2 and WS902) indicating the wind effect. The data obtained in the wind tunnel were later used to do the MLR study with new predictors for indicating wind effect (∆Cp∙WS, ∆Cp∙WS2, ∆CpOUT-IN·A∙WS, ∆CpOUT-IN·A∙WS2, ∆CpC-H∙WS, ∆CpC-H∙WS2). Better prediction of ACH was obtained with the square of the wind speed (WS2) instead of the magnitude itself (WS). However, the latter (WS) provided better results than the regression with the magnitude of the perpendicular component of the wind (WS90). Although wind speed influences in ACH, it alone seems to be a very poor predictor of ACH since has a negative correlation with ΔT when the data under study include both day and night. However when high wind speed are detected it has quite strong influence. The most significant predictions of ACR were attained with the combined predictors ∆T & WS and ∆T & ∆CpOUT-IN·A∙WS2. The main conclusion taken from the MLR analysis is that the stack effect is the most significant factor influencing the ACH inside the church hall. This leads to suggest that an effective way of reducing ACH could be sealing the floor and ceiling of the church because from those areas the air infiltration has big influence on the ACH inside the church hall, and more in this case that have been noted that the floor is very leaky. Although different assumptions have been done during the analyses that contribute to make the predictions deviate from reality, at the end it would be possible to asses that MLR can be a useful tool for analyzing the relative importance of the driving forces for ACR in churches and similar buildings, as long as the included predictors not are too mutually correlated, and that attained models that are statistically significant also are physically realistic. / Church project