Theodore Stathopoulos's research while affiliated with Concordia University Montreal and other places

Publications (66)

Article
This study introduces a novel approach for the modelling of convective phenomena for air-based building integrated photovoltaic thermal (BIPV/T) systems, which takes into consideration the interlinked nature of wind-driven and channel flow-driven convective phenomena. Expressions for wind-driven and channel convection used in the respective literat...
Article
This paper presents the design, development and experimental testing of a Building Integrated Photovoltaic/Thermal (BIPV/T) curtain wall prototype. The main purpose of this study was to address the lack of design standardization in BIPV/T systems, which has been identified as a major factor for the limited number of applications of such systems, by...
Article
This article presents a review of the monitored performance of air-based photovoltaic/thermal (PV/T) and building integrated photovoltaic/thermal (BIPV/T) systems, as well as the relevant system modelling with focus on the convective phenomena. The review showed that the majority of experimental studies involve small-scale PV/T prototypes of the st...
Conference Paper
In this paper the energy potential of an innovative Double Skin Façade integrating Photovoltaics (DSF-P) for different weather conditions is investigated. The proposed system consists of semi-transparent and opaque PV modules integrated in the exterior skin of the façade and active shading devices implemented within the cavity. The innovative singl...
Article
Wind induced convection is the main cause of heat loss for roof-mounted solar collectors. In this study the importance of using the actual wind velocity distributions over the whole roof area, instead of a commonly assumed single velocity of a reference location, is addressed through experimental measurements and numerical assessment of the perform...
Article
Air-based, open-loop Building Integrated Photovoltaic/Thermal (BIPV/T) systems are an efficient means for generating electricity and useful heat from incident solar energy. However, due to the low heat exchange efficiency of air, overheating issues may occur that can reduce the electrical production of the system, as well as its durability. With th...
Conference Paper
A numerical model is developed for a multi-story Double Skin Façade integrating Photovoltaics (DSF-P). The model has the ability to predict the thermal and electrical performance of the DSF-P system. The air flow inside the cavity may be assisted by a fan to cool down the photovoltaics while providing natural or hybrid ventilation to adjacent zones...
Conference Paper
A numerical model is developed for simulating a single or multi–story Double Skin Façade integrating Photovoltaics (DSF-P). The proposed model enables the prediction of the thermal and electrical performance of the DSF-P system. The DSF-P can co-generate solar electricity and heat. The buoyancy-driven air flow inside the cavity may be assisted by a...
Article
Full-text available
Building Integrated Photovoltaic/Thermal (BIPV/T) collectors take up the role of energy and heat production, while acting as a rain-screen cladding. A multiple inlet BIPV/T system counters the effect of high temperature stratification on the PV layer, by enhancing the convection inside the air channel with the introduction of more than one openings...
Article
High wind velocity affects the performance of unglazed transpired collectors (UTC); indeed, wind flow on the collector’s surface reduces useful heat transferred to the collector fluid by effectuating convection losses and suction in the pores and thereby outflow from the plenum. Wind does not impinge uniformly on all points on a large area; the vel...
Article
High wind velocity affects the efficiency of unglazed transpired collectors (UTC) by effecting convection losses and suction in the pores. Local wind velocities impinging on a surface differ from the approach wind velocity due to obstructions and redirection caused by surrounding structures. This paper describes an experimental study in a wind tunn...
Conference Paper
Full-text available
The state of the art is presented in the field of structural vulnerability assessment under earthquake, landslide, tsunami and wind hazards.We seek common avenues of research and points of contact among the existing philosophies used in these four different fields in the context of multi-hazard assessment frameworks. In essence, this is a step towa...
Conference Paper
Computational Fluid Dynamics (CFD) methods have been used for calculating wind flow around buildings and predicting pedestrian wind conditions. Compared to the traditional wind tunnel testing, CFD has the potential to be more efficient and its graphic presentation of wind flow fields is particularly attractive to architects and planners. Attempts h...
Article
Full-text available
Outdoor human comfort in an urban climate may be affected by a wide range of weather and human factors. This paper describes a research program investigating the comprehensive relationship between the comfort level of typical human activities and major weather parameters through questionnaire surveys, field measurements and statistical analyses. Th...
Article
Previous studies have shown that Computational Wind Engineering (CWE) is still in its infancy and has a long way to go to become truly useful to the design practitioner, The present work focuses on more recent studies to identify progress on outstanding issues and improvements in the numerical simulation of wind effects on buildings. The paper revi...
Article
Problems and discrepancies have been found in the provisions of exposure factors (Ce) when comparing different national wind standards and codes of practice, as well as when examining experimental findings in relation to code predictions. Difficulties have also been found in the application of current Ce provisions for design in case of complex ter...
Article
The paper addresses the suitability of wind pressure coefficients specified in contemporary design standards and codes of practice for gable roofs of intermediate slope (roof angle ). In a recent research study, a series of low building models with different roof slopes in this intermediate range were tested in a boundary layer wind tunnel under si...
Article
Wind-induced interference effects on a building are the result of one or more adjacent buildings modifying the flow of wind around it, which may result in a significant increase or decrease in wind loads on the building. Wind loading standards and codes of practice offer little guidance to the designer for assessing the effects of interference. Exp...
Article
This paper describes the experimental data obtained in a full-scale wind-pressure study on a low-rise building, 3.3m high, located beside a football field on the Loyola Campus of Concordia University in Montreal. Mean wind-induced pressures have been measured on 12 roof corner points for several wind directions. A series of building models were als...
Article
This paper describes a new experimental method using infrared thermography for the evaluation of wind impact at pedestrian level. The developed measurement system consists of a heated plate on which building models stand, an infrared video camera for detecting the surface temperature distributions on the heated plate, and a microcomputer for image...
Article
Current data storage and computational capabilities allow the development of a new generation of standards whose provisions on wind loads can be structured as knowledge-based systems drawing the requisite information from large data bases. We show several examples demonstrating that such provisions could be significantly more realistic and risk-con...
Article
Current data storage and computational capabilities allow the development of a new generation of standards whose provisions on wind loads can be structured as knowledge-based systems drawing the requisite information from large data bases. We show several examples demonstrating that such provisions could be significantly more realistic and risk-con...
Article
The paper reviews the current state of the art in computational wind engineering, particularly as it relates to applications of numerical flow modelling for the evaluation of wind effects on buildings and their environment. The variability of computational results is presented and compared with that of wind tunnel measurements. Concerns are express...
Article
The two-layer methods combining the k-ε model in the external, fully turbulent flow region with either the one-equation model or the low-Reynolds-number modified k-ε model in the near-wall area have been tested in computing the wind conditions around a cubic building. Results were compared with those from the k-ε model computation as well as those...
Article
A knowledge-based system has been developed for the evaluation of the pedestrian-level wind environment around buildings. This paper presents the system with emphasis on two of its major components dealing with the utilization of meteorological records and the recommendation of remedies to improve the wind environment, for which statistical analyse...
Article
Wind conditions over streets in built-up cities were examined in a boundary-layer wind-tunnel model study. Presented in this paper are results of wind speeds affected by a number of parameters such as the spatial density of street blocks, the building height over surroundings, the relative location of buildings and the direction of approaching wind...
Article
Wind loading is one of the most sophisticated requirements in building envelope design. The importance of wind loading depends on a number of factors such as building dimensions and geometries, surroundings, terrains and wind conditions. The evaluation process for wind loading on buildings, usually laborious and error-prone, could be automated by u...
Article
A wind-tunnel study has been carried out to assess wind loads on multispan gable roofs with roof slopes of 4:12 and 12:12. Local and area-averaged pressure coefficients were measured on models with one, two, and four spans. Critical suctions were significantly larger than those specified for single-span roofs in wind standards. Discrepancies betwee...
Article
Wind standards and codes of practice specify design pressure coefficients for eaves of low buildings with gabled roofs of angles smaller than 10°. The paper presents the results of a recent experimental study on the effects of wind on eaves of gabled-roof buildings with higher roof slopes, namely 4:12 and 12:12. The experiments were carried out in...
Article
Tree windbreaks form an important mechanism for reducing wind-induced air infiltration in buildings. However, they also affect wind loading determined mainly by wind standards and building codes of practice for a homogeneous terrain environment. A wind tunnel study was carried out to examine the effects of various tree configurations on wind-induce...
Article
Wind conditions around high-rise buildings in cities may create serious environmental problems at the pedestrian level. In spite of the progress of computational techniques in wind engineering, wind-tunnel experiments are still considered to be the most reliable approach for the evaluation of pedestrian-level winds. A number of techniques have been...
Article
The paper presents the numerical prediction of turbulent wind pressures on the surfaces of L-shaped buildings (either in plan view or in cross section) for different wind directions. The computer program developed for this purpose solves the time-averaged Navier-Stokes equations by using the k-E turbulence model for closure. A zonal treatment metho...
Article
Wind pressures on buildings may be affected by various appurtenances such as mullions or vertical ribs. The determination of the influence of these appurtenances on the wind loads on cladding and structural elements of a building is important in order to identify any modifications necessary for the provisions of wind codes of practice and design st...
Article
The paper refers to a new experimental approach applied in a boundary layer wind-tunnel experiment that tests the transient response of the wind-induced internal pressure in a building when a sudden opening occurs. This topic has been examined analytically in the past. It has been found that the internal pressure may become much higher than the ext...
Article
The effect of parapets on the wind loading of flat roofs has not been examined in detail in the past. This paper refers to the experimental data obtained in a recent study of the effects of wind on a variety of flat roofs with and without parapets when exposed to simulated atmospheric boundary layer flows (open country and urban exposure). Geometri...
Article
Wind-induced internal pressures in buildings can be analytically evaluated by using external pressure coefficients appropriate for each surface of the building envelope. The evaluation considers the overall building porosity and the specific (intentional or unintentional) wall (or roof) openings. Analytically-evaluated internal pressure coefficient...
Article
Presently, fatigue is not considered a critical design factor for low metal buildings exposed to severe wind storms. Fatigue however, has been shown to be the only possible cause of several roof failures which occurred during cyclones. A simple approach for the evaluation of wind-induced fatigue on low buildings is presented. The number and distrib...
Article
The effect of large nearby buildings on the wind loading of low buildings has not been examined in the past. Wind loads for low buildings specified by current standards and Codes of Practice originate from wind tunnel studies on isolated buildings and give no guide for the assessment of loads under conditions of buffeting. The current paper present...
Article
This paper refers to the most recent research on wind loads on low-rise buildings. Novel measurement techniques and methodologies are reviewed, and selected experimental results from various studies are presented. Particular emphasis is given to works aimed at the formulation of codified data, i.e. results appropriate for incorporation into design...
Article
Further analysis of wind loads derived from boundary layer wind tunnel experiments on low buildings sheds light on the question of scaling. Results are available for building models tested at three geometric scales under two different terrain exposures representing open country and suburban areas. Both mean and fluctuating pressure coefficients app...
Article
Innovative techniques for the measurement of mean and fluctuating wind loads acting over various tributary areas of wind tunnel models are described. Pneumatic manifolding, designed to provide good dynamic response, allows effective loads over large areas to be measured which inherently account for lack of spatial and temporal correlation in the un...
Article
Quasi-steady theory can be used for the prediction of fluctuating wind pressure coefficients acting on the edge strip of flat or low-sloped roofs and the ridge strip of steeper roofs of low buildings. Comparisons with experimental data indicate that the quasi-steady model, expressing the root mean square pressure coefficients as functions of mean p...
Article
This paper presents the results of a recent experimental study carried out in a boundary layer wind tunnel to determine the wind loads on low-rise buildings of different configurations with and without parapets. Data show that the addition of parapets reduces the magnitude of roof peak suction coefficients with values greater than about 1. 75 for o...
Article
Weighted Legendre polynomials are shown to represent adequately the distribution of mean and root mean square (rms) wind pressure coefficients on rectangular flat roofs for wind normal to the building faces. Peak pressure coefficients cannot be fitted by the same analytical model, but their variation can be represented from the mean and rms pressur...
Article
A series of full-scale structural static and dynamic tests were performed to characterize selected properties of a 1200-kV mechanical test line. Prior to the experiment tests, a finite-element analysis of the test tower was conducted. The analytical techniques used to determine the static dynamic behaviour of a transmission tower will provide satis...
Article
An experimental investigation of wind-induced pressure loads acting on two square-plan flat-roofed model structures (50ft and 225ft high in full scale) is described. Measurements of mean, peak, and root mean square pressures acting on points and over larger roof areas have been made in turbulent boundary layer flow simulating wind over urban and op...
Article
Probability distributions of wind pressures acting on points or areas of low-rise building models have been measured in turbulent boundary layer flow simulating wind over open country and suburban terrains. Results show extensive positive and negative tails for high negative and positive mean pressure coefficients, respectively. Probability density...
Article
The two-storey house at Aylesbury, England, built by the Building Research Establishment for the full-scale measurement of wind pressures, has been modelled at 1:500 scale in a boundary layer wind tunnel so that the reliability of simulation could be verified for low-rise buildings. Wind tunnel tests of building models of 5° and 22.5° roof slope ar...
Article
A pneumatic manifolding technique is suggested as an economical means for evaluating time-varying spatially-averaged pressure loads on tributary areas of design interest on building models. Results of some exploratory experiments are presented which show that mean and r.m.s. pressures can be determined accurately by such manifolds. Furthermore, the...
Article
Building integrated photovoltaic/thermal (BIPV/T) systems serve two purposes – generate electricity and heat ambient air using absorbed solar energy. High wind velocity reduces the efficiency of unglazed transpired solar collectors (UTC). Indeed, wind flow on the collector's surface reduces the useful heat transferred to the plenum air by effectuat...

Citations

... The investigation is carried out in diverse European weather zones concluding that air based BIPV/T adoption could reduce the final thermal energy demands up to 16% by also providing a remarkable contribution by the electric point of view. BIPV/T passive effects are investigated by several researchers, such as Yang et al. [44], Theokli et al. [45], Rounis et al. [46] and Yang et al. [47]. For example, Yang et al. [44], resent a sensitivity analysis of the design parameters of a BIPV/T double skin façade. ...
... 3. The PV cells are assigned as a single temperature because of the negligible thermal resistance of the PV module. 4. The one-dimensional heat flow of the wall is assumed, normal to the surfaces of the evolope [30]. 5. ...
... Use of scaled building models in the thermal environment analysis were in practice for several decades as reported by Yoon et al. [19,20]. On the other hand, there are numerous literary proofs of the analysis on (a) wind effects [21], (b) solar power utilization [22] and (c) thermal performance in comfort potential of low-rise or shallow buildings [23]. Similarly, Nahar et. ...
... Several technologies were proposed to have stationary shading elements above or in front of windows which provide solar thermal energy, too (Abu-Zour et al., 2006;Oliveira, 2006, 2010;Li et al., 2016). There are many developments on BIPVT like (Buonomano et al., 2016;Athienitis et al., 2017) which exceed the scope of this paper. ...
... From this plot, it can be concluded that flat plate collector efficiency decrease with an increase in wind velocity. This is because as wind velocity increases it reduces the effect of solar intensity and cool the collector fluid by natural convection, and reduces ambient temperature [15]. Figure 6 shows a variation of efficiency of the collector on different days with the time of day. ...
... The first two configurations recorded significant outlet air temperatures suitable for different applications of HVAC systems and domestic hot water preheating while configuration 3 reduces the electricity production by increasing the temperature of the PV panel. Rounis et al. [55] also performed a comparative study between a single and a multiple-inlet BIPV/T system design, for a possible retrofit or new building, presenting an example of a potential large-scale installation on an office building. The results showed that the multiple-inlet BIPV/T system may have higher electrical efficiency, additional power, higher thermal efficiency and lower and more uniform PV temperatures. ...
... Lin and Surry (1998) and Lin et al. (1995) showed that, for low buildings which are large enough to have reattached flows on the roof, the distribution of pressure coefficients in the corner region is mainly dependent on the eave height, H, and not so much on the building plan dimensions for similar terrain conditions. Moreover, external pressure coefficients measured in the wind tunnel by Kopp et al. (2005) on roof corners of a nearly flat building model were consistent with those measured on roof corners of flat roof low-rise building models with the same height but with different plan aspect ratios (Stathopoulos 1982, Stathopoulos and Baskaran 1988, Pierre et al. 2005. ...
... Risk management of the built environment is a challenging problem from an engineering perspective [11][12][13][14][15][16][17], since it involves several uncertain parameters [18][19][20][21]. These are mainly: actual loads acting on the structure [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39], building damage due to impacts from flying debris [40][41][42][43][44][45][46][47][48][49][50], responses of roof-to-wall connections [51][52][53][54][55], increased internal pressure and wind loads [24][25][26]37], subsequent water intrusion [11][12][13][14][15][16][17][56][57][58][59][60][61][62], amplified financial loss [19][20][21] and even construction deficiencies causing water intrusion losses [56]. Researchers have relied on fragility-based approaches [11][12][13][14][15][16][17] to propagate parameter uncertainties to eventual dollar loss. ...
... It should be noted that the provisions in wind loading standards are derived from the data collected from extensive wind tunnel tests and long-term field measurement campaigns conducted for low-rise buildings. For example, the data of wind pressure obtained from wind tunnel tests conducted by Davenport et al. [4], Davenport et al. [47], Holmes, [12,13]; Stathopoulos [48], Stathopoulos & Zhu [41], Stathopoulos & Luchian [39], Stathopoulos & Saathoff [40], as well as the full-scale measurements from a single-family dwelling [22], the Aylesbury Test Building the Silsoe 6 m cube at the Silsoe research institute [5,35], and Wind Engineering Field Research Laboratory (WEFRL) at Texas Tech University [21] paved the way to establish the provisions given in major internal wind loading standards for estimating wind pressure of low-rise buildings. ...