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Existing buildings consume most of our non-transportation related energy and are a major contributor to the emission of greenhouse gases. Improving their energy efficiency by applying energy conservation measures (ECMs) remains a major challenge. This paper presents computational tools developed to screen office buildings for retrofit and to select specific ECMs for each building. This selection process accounts for climate, occupancy, building operation, heating and cooling systems, distribution systems, envelope properties, building geometry, and cost of ECMs. The tools screen the complete building set for optimal retrofit opportunities. The methodology adopted in developing the computational tools includes characterization of the office building stock into a manageable set of archetypes; simulation of building operation using specific occupancy characteristics and local climate data; development of energy prediction models for lights, equipment, pumps, fans, domestic hot water, chillers, and boilers; and application of present value analysis to evaluate the cost effectiveness of ECMs. Key words: energy, modelling, office buildings, retrofit, screening. Les batiments existants consomment la majorite de l'energie non reliee aux transports et sont des contributeurs importants a l'emission de gaz a effet de serre. Ameliorer leur efficacite energetique par l'application de mesures d'economies d'energie demeure un grand defi. Cet article presente des outils de calculs developpes pour preselectionner les immeubles de bureaux en vue d'une mise a niveau et pour choisir les mesures d'economies d'energie specifiques a chaque immeuble. Ce processus de selection tient compte des conditions climatiques, de l'occupation, du fonctionnement de l'immeuble, des systemes de chauffage et de ventilation, des systemes de distribution, des proprietes de l' enveloppe, de la geometrie de l'immeuble, ainsi que des couts des mesures d'economies d'energie. Les outils evaluent l'immeuble au complet qui a ete choisi pour les mises a niveau optimales. La methodologie adoptee lors du developpement des outils comprend la caracterisation de l' immeuble de bureaux au completen un ensemble gerable d' archetypes, la simulation du fonctionnement des immeubles en utilisant des caracteristiques specifiques d'occupation ainsi que les donnees locales sur les conditions climatiques, le developpement de modeles de prevision energetique pour les lumieres, les equipements, les pompes, les soufflantes, l'eau chaude domestique, les refroidisseurs et les chaudieres, de meme que l'application de l'analyse des valeurs actualisees afin d'evaluer le rapport cout-efficacite des mesures d'economies d'energie. Mots-cles : energie, modelisation, immeubles de bureaux, mise a niveau, preselection. [Traduit par la Redaction], 1. Introduction Within the commercial and institutional sector, office buildings make up 41% of the energy use (Natural Resources Canada 2008). Studies on reducing office buildings' energy consumption have shown [...]

Constitutive equations for fresh mortar and fresh concrete provide the characterization of the mixture's flow and the quantification of the rheological properties. This paper presents a constitutive material model for mortar and concrete that builds on previous research. It postulates that (a) the shear stress is the sum of three components: static interaction between particles, dynamic interaction between particles, and collision of particles; and (b) the cell is a representative volume of the mixture. For fresh concrete, the effects of particle collisions are negligible due to high concentration, and the equation reduces to the Bingham model. Experimental data reported in the literature was employed to evaluate the predictive capabilities of the constitutive equations. The model results are found to compare very well with the measured experimental data and the difference is within the measurement errors. Key words: mortar, concrete, constitutive equations, rheology, workability, cell method. Les equations de comportement pour le mortier frais et le beton frais permettent de caracteriser l'ecoulement du melange et de quantifier les proprietes rheologiques. Cet article presente un modele de comportement des materiaux, le mortier et le beton base sur le travail des recherches anterieures. Il presume que (a) la contrainte en cisaillement est la somme de trois composantes : l'interaction statique entre les particules, l'interaction dynamique entre les particules et la collision des particules, et (b) la cellule constitue un volume representatif du melange. Pour le beton frais, les effets des collisions entre les particules sont negligeables en raison de la forte concentration, et l' equation se resume au modele Bingham. Les donnees experimentales rapportees dans la litterature ont ete utilisees pour evaluer les capacites predictives des equations de comportement. Les resultats du modele se comparent tres bien aux donnees experimentales mesurees et la difference est dans la plage des erreurs de mesure. Mots-cles : mortier, beton, equations de comportement, rheologie, maniabilite, methode des cellules. [Traduit par la Redaction], 1. Introduction Characterizing the rheological properties and behaviour of fresh concrete is an important step toward controlling the quality of concrete (Chidiac et al. 2000, 2003; Ferraris et al. 2001). [...]

The main focus of this paper is on the evaluation of local a posteriori error estimation techniques for the finite element method (FEM). The standard error estimation techniques are presented for the coupled displacement fields appearing in elasticity problems. The two error estimators, the element residual method (ERM) and Zienkiewicz--Zhu (ZZ) patch recovery technique, are evaluated numerically and then used as drivers for a mesh adaptation process. The results demonstrate the advantages of employing a posteriori error estimators for obtaining finite element solutions with a pre-specified error tolerance. Of the two methods, the ERM is shown to produce adapted meshes that are similar to those adapted by the exact error. Furthermore, the ERM provides higher quality estimates of the error in the global energy norm when compared to the ZZ estimator. Key words: mesh adaptivity, a posteriori error estimation, element residual method, Zienkiewicz-Zhu patch recovery. Resume: Cet article porte principalement sur l'evaluation des techniques d'estimation des erreurs a posteriori pour la methode des elements finis. Les techniques d'estimation de l'ecart-type sont presentees pour les zones de deplacement couple presentes dans les problemes d'elasticite. Les deux estimateurs d'erreur, la methode des elements residuels (<< ERM >>) et la technique de recuperation par patch du type Zienkiewicz-Zhu (ZZ), sont evalues de maniere numerique puis utilises comme base d'un processus d'adaptation des mailles. Les resultats montrent les avantages d'utiliser des estimateurs d'erreur a posteriori afin d'obtenir des solutions par elements finis avec une tolerance d'erreur predeterminee. Des deux methodes, << ERM >> produit des mailles adaptees similaires a celles adaptees par l'erreur exacte. De plus, l'ERM fournit des estimations de meilleure qualite de l'erreur dans la norme d'energie globale lorsque comparee a l'estimateur de type ZZ. Mots-cles: adaptabilite des mailles, estimation de l'erreur a posteriori, methode des elements residuels, recuperation par patch du type Zienkiewicz-Zhu. [Traduit par la Redaction], 1. Introduction The finite element method is an optimal method for solving elasticity problems appearing in structural mechanics. It is optimal in the sense of minimizing the total potential energy [...]

Abstract: The optimization of the production of fired clay brick is essential for the sustainability of the clay brick industry. While there exist areas for improvement of these bricks' properties [...]

Abstract: Performance of dry-cast concrete masonry products (DCCMPs), which are becoming the product of choice for many applications, has yet to be assessed in a comprehensive manner. This study was [...]

Abstract: This study evaluates the potential use of ultrasonic pulse velocity (UPV) for determining the early age Compressive strength of dry-cast concrete containing varying percentages of ground granulated blast-furnace slag [...]

Premature deterioration of concrete structures has created awareness and concern about the durability of concrete. Concrete mixtures used in the construction of residential basement walls and foundations have a high water to cement (w/c) ratio (w/c> 0.6) and low cement content (< 280 kg/[m.sup.3]). The result is friable concrete with a highly porous surface layer and high potential for cracking. The defects have a direct impact on the durability of concrete. This experimental study examines the effects of three parameters--mix design, formwork, and consolidation--on the quality of the surface of high w/c concrete. The fresh concrete is characterized using its rheological properties--in particular, its yield stress and plastic viscosity. Pulse velocity, pull-off strength, and compressive strength were measured to evaluate the quality and the mechanical properties of the hardened concrete. The durability of the hardened concrete was evaluated by measuring its surface transport properties--namely, its air permeability and sorptivity. The results show that it is possible to correlate the rheological properties of fresh concrete to the mechanical and permeation properties of the hardened concrete. CE Database subject headings: Concrete durability; Sorption; Permeability; Vibration; Admixtures; Rheological properties; Correlation.

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Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)