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Automating the checking of building envelope design according to design regulations is a complex process because these regulations consist of complicated logic sentences covering multiple functions. Existing mechanisms of building code computer-aided checking have some limitations dealing with design regulations. This paper presents a new integrated approach to automated code compliance checking for building envelope design based on simulation results and building codes. In this approach, building codes and simulation results are seamlessly linked with the compliance checking software. A hierarchical object-based representation of simulation results is proposed as an extended building information model (EBIM) to describe the attributes of a building and its subsystems. A representation of building codes based on decision tables and compatible with the EBIM is also proposed so that users can check the building envelope design against building codes based on the standardized simulation results. A prototype system is developed and a case study gives an example of evaluating the hygrothermal performance of an exterior wall. DOI: 10.1061/(ASCE)0887-3801(2010)24:2(203) CE Database subject headings: Standards and codes; Building envelope; Design; Computer applications. Author keywords: Design code; Compliance checking; Building envelope.

Several existing certification programs and assessment tools that evaluate housing performance are presented in this paper, showing that there is global trend in defining and evaluating the overall building performance. [...]

Coordination of design information during the detailed design stage is essential for the design team to provide quality construction technical documents that are free of incompatibility errors. An analysis concerning current design coordination practices in the building industry revealed that design changes constitute a major cause of failure. More specifically, propagation of changes among the various design disciplines is deficient due to lack of required 'linking' knowledge. Such knowledge is necessary to propagate the effect of a design change by one discipline on the other disciplines involved in the design of a building. This paper presents an information model that aims to help the coordination of design information through managing design changes. The model uses a central database, which is developed not only to carry the building components data, but also to make these components active in assisting the coordination process. In addition to its ability to propagate design changes, the model is capable of tracking past changes and helping in the planning and scheduling of future ones. This paper focuses on the development of the information model and illustrates its implementation.

This paper presents a decision-support system (DSS) that aids contractors in preparing competitive bids for building projects. The DSS uses neural networks for markup estimation that derive solutions for new bid situations based on analogy with past projects using information elicited from contractors in Canada and the United States. The neural networks were trained to generalize the projects' knowledge and thus become able to predict the outcomes of a project when fed with the contractor's assessment of various project risks. The proposed DSS is coded in a user-friendly software called DBID. The software enables the contractor to retrain the neural networks on some of his or her past bid encounters and accordingly adapt the model to his or her own environment. In estimating the optimum markup for a new project, the uncertainty in the contractor's assessment of project risks is accounted for by a sensitivity analysis conducted using the Monte Carlo simulation technique. Such analysis produces a measure of the probability of winning at any desired level of markup. The capabilities of the present DSS are demonstrated through an example application.

This paper addresses the effective use of various levels of automation in concrete slab-on-grade construction, considering conventional manual construction, semiautomated placing using a laser-guided screeding machine and automated finishing using a robotic floor finisher. For both manual construction and semiautomated placing, information is obtained through structured interviews of concrete contractors and site observations. Information on robotic finishing is obtained from robot developers. When compared to the conventional manual construction of a typical 1,859-m squared, 150-mm-thick slab, accomplished in 10 hours with a 12-man placing crew and a six-man finishing crew, automation of finishing alone is found to offer benefits through a 30% reduction in the size of the finishing crew, whereas automation of placing alone offers benefits through a 33% reduction in the placing crew size and a 20% activity-duration reduction. Automation of both placing and finishing allows a 33% placing-crew-reduction, 25% finishing-crew increase, and a 60% activity-duration reduction. These benefits are considerably increased when higher quality is explicitly specified.

The thermal performance of structural insulated panels (SIP) and connections, developed and used to build 142 homes in Nunavut, Canada, was studied by subjecting the panels to steady-state cold climate conditions in a laboratory test setup. Testing was carried out using an inverted test hut, in which the panels were installed such that the interior of the hut was cooled down to outdoor conditions, and the ambient lab conditions served as the indoor climate. This inverted setup provides an alternative to using a large-scale environmental chamber when this is not available. Results showed the methodology used in this test is adequate to characterize the thermal performance at both the center of the panel and the connections. In carrying out steady-state thermal simulations on both the panel and connection cross sections using both onedimensional (1D) and two-dimensional (2D) programs, it was found that while the 1D simulation could adequately predict the performance at the center of the panel, a 2D simulation was required to predict the performance at the connections. The SIPs themselves were found to provide good thermal performance. [ABSTRACT FROM AUTHOR]

A building shall be classified as high performance building if it is energy efficient and durable and at the same time provides comfortable and healthy indoor environment for occupants. To achieve this objective, the hygrothermal performance of alternative building designs should be evaluated based on the simultaneous analysis of these three functional requirements rather than separately. In this article, a Whole-Building Hygrothermal model is used for evaluation of various retrofit design parameters that potentially enhance the overall performance of an existing residential house. The retrofit options considered in this study include changes to the reference house’s ventilation rate and operation, windows, insulation level, and various combinations of these options. Energy efficiency, building envelope and moisture management potential, indoor humidity control, and window condensation potentials are considered to be the four performance indicators in searching for a retrofit option that delivers an optimal performance. The hygrothermal simulation results indicate that changing a design parameter to improve one of the design goals may result in less optimal results in the other one or both goals, or even in some cases result in severe negative consequences. [ABSTRACT FROM PUBLISHER]

Complex fenestration systems (CFS) need to be evaluated to quantify how well they contribute to avoid glare and manage the solar heat gains through building façades. It is possible to use solar bidirectional properties of CFS in some building energy simulations tools in order to evaluate more accurately their impact on lighting, cooling and heating energy consumption.genBSDFis a Radiance's program whose capabilities of assessing the bidirectional solar properties of CFS are evaluated in this paper. This evaluation was carried out for 16 cases of a venetian blind varying the solar properties and slope angle of the slats. Results of directional and bidirectional solar properties obtained bygenBSDFwith radiosity assumptions were compared with the results of the radiosity-based WINDOW algorithm. Results show an excellent agreement between the two approaches which demonstrates thatgenBSDFis a very precise and robust tool for assessing the solar bidirectional properties of CFS. [ABSTRACT FROM AUTHOR]

Validated by a large-scale experimental investigation on moisture buffering (MB) effect, a whole building Heat, Air and Moisture (HAM) simulation tool, BSim, is applied to evaluate the impact of a number of parameters on the moisture buffering potential of a full-scale test room finished with hygroscopic materials. The Maximum Accumulated Moisture Buffering Value (MAMBV), developed from the moisture balance analyses in the experimental study, is used in the BSim simulation result analyses to evaluate the impact of various parameters. The parameters investigated include ventilation rates (0.5-5 ACH), types of materials (uncoated gypsum board, wood paneling, orientated strand board, aerated cellular concrete, and telephone book paper), humidity conditions of supply air, volume rates, and steady-state outdoor conditions. It is found that all these parameters have a significant impact on the moisture buffering potential except for the steady-state outdoor conditions. Two material properties, the moisture capacity and vapor permeability, determine the moisture buffering capacities of materials under different moisture generation regimes. [ABSTRACT FROM AUTHOR]

Moisture-related building envelope failures have resulted in costly rehabilitation in various regions of North America. To advance building envelope design towards an engineering approach and reduce the occurrence of future failures, an advanced numerical tool was developed, in conjunction with an extensive full-scale experiment, to investigate hygrothermal performance of various wood-frame wall assemblies. Major features of the tool are multi-dimensional and transient coupling of heat and moisture transport; natural air convection integrated in hygrothermal simulation through Darcy–Boussinesq approximation; heat transfer by conduction and convection of sensible and latent heat; moisture transport by vapor diffusion, capillary suction and convection; material database of common building materials in North America; experimental settings or weather data as boundary conditions; and moisture added in the building envelope to simulate the wetting process. The numerical tool achieves good compliances to the benchmarking cases of the HAMSTAD project, and its predictions have shown good agreement with data from the full-scale wall experiment. The numerical tool employs the commercial finite-element software to solve the governing equations. This approach provides building science researchers the flexibility to modify, maintain and share their modeling work efficiently. [Copyright &y& Elsevier]

Abstract: In the context of a collaborative research project with industry and government, a two-story test hut, consisting of thirty-one 2438mm (8ft) high and 762mm () wide wall assemblies and installed with 25 gravimetric samples in each assembly to monitor the moisture content change, was designed and erected within a large-scale test chamber to investigate the drying capacity of different envelope configurations. The test was performed under steady-state climatic loadings representing wet seasons. Uniform moisture loading was achieved by the use of water trays on load cells placed on the bottom plate within the stud cavities of the wall assemblies. This method submits the different wall configurations to wetting by evaporation and drying by evacuating moisture out of the stud cavity. In search for an indicator or yardstick of the relative drying capacity of different wall configurations, a new calculation method by mapping was developed. The method estimates the amounts of moisture absorbed by components surrounding the stud cavity. The moisture transported out of the cavity is the difference between the total water evaporated from the tray and the water absorbed by the wall components. The ratio between the water evaporated and the vapor evacuated is an indicator of the drying capacity of a given wall configuration in relation to others subjected to a predetermined set of conditions. [Copyright &y& Elsevier]

The moisture buffering capacities of five building materials which are widely used in North America was investigated experimentally. An experiment to quantify the moisture buffering capacity of building materials was developed. Hygrothermal properties of these building materials, reported in this paper, include the density, thermal conductivity, equilibrium moisture content, water vapor permeability, water absorption coefficient, and air permeability. Moisture buffering test results showed that among these materials the fiberboard product has the best moisture buffering capacity, whereas plywood has the lowest among the building products tested. [ABSTRACT FROM AUTHOR]

Rainwater penetration is the source of moisture that causes the greatest damage to building envelope assemblies. The building envelope should be designed to reduce the amount of rainwater penetration by deflection and drainage. Since it is not realistic to assume a perfect wall without any leakage, the envelope should have the drying capacity to tolerate defects that may arise from the design, construction, and aging of the exterior wall system. Systems with a greater capacity to evacuate moisture from the stud cavity are less likely to undergo moisture damage. A new testing method is developed and deployed to evaluate the relative drying capacity of six wood-framed wall panels of different configurations built into a test hut and tested within a large scale environmental chamber. The wall panels used plywood, oriented strand board (OSB), or fiberboard as sheathing, but did not include cladding. A uniform moisture source was introduced in a water tray set on a load cell at the bottom of each stud cavity. The protocol is based on the hypothesis that the potential for moving a water molecule from the bottom plate to the exterior of the stud cavity is independent of the previous journey of that molecule, i.e., whether it has traveled from the interior of the bottom plate to the surface of the plate or whether it comes from free water in a tray at the level of the bottom plate. For a given set of boundary conditions, this potential is a function of the characteristics of the wall panel, and is identified as the drying capacity of the panel or its drying by evaporation index (DEI). The value of DEI corresponds to the evaporation rate. The moisture response of wall materials enclosing the stud cavity and the evaporation rate of the moisture source were monitored. The results show that this index can be used as an indicator of the relative drying capacity of different wall systems. [ABSTRACT FROM AUTHOR]

This paper presents a method for the field measurement of airtightness for two- and three-unit buildings using only one fan pressurization system, commonly referred to as a blower door. The main advantage of this single-fan method is its lower equipment and labor cost as compared with multiple-fan methods. Results from consecutive tests in the individual units are used to prepare a set of simultaneous equations for airflow, allowing for the calculation of the air leakage characteristics of both the interior partitions and the exterior envelope on a unit-per-unit basis. Tests were performed on four buildings using the single-fan method and were compared with those obtained with a two-fan method. Test results indicate that the single-fan method may be of value as an inexpensive method of estimating the airtightness of two- and three-unit residential buildings. [ABSTRACT FROM AUTHOR]

A computer model was extended and adapted to simulate the hygrothermal behavior of building envelope-wood components. The model was used to predict moisture movement in wood planks forming the decks of nonvented flat roofs insulated with cellulose. The gradient of water potential was considered as the driving force for moisture movement in wood. The model required the determination of convective heat- and mass-transfer coefficients, the sorption curves, the effective water conductivity for different wood species, and the hygrothermal conditions within the assembly to characterize the mass-conservation equation. Once these parameters were integrated in the computer model, this approach was then validated by carrying a simulation of the drying process of wood planks using experimental data from a large-scale test. [ABSTRACT FROM AUTHOR]

The fan pressurization method for measuring air leakage through the building envelope relies on the assumption that the extraneous air leakage (EAL) through paths other than those through the specimen being tested is negligible. When EAL does exist, the calibration procedure by ASTM Standard E-283 is used to measure EAL values by covering the specimen or guarded chambers are used to equalize the pressure differences across these unintended paths. A new testing method, the flexible double-chamber method, is presented in this paper for large specimens where the above two approaches are difficult to implement and where flexible chambers are more easily applied. The experimental procedure and data processing routine are presented for the case of a full-size metal curtain wall specimen. The EAL is estimated by regression analysis in data processing. Inference analysis, multivariate error analysis, and the Monte Carlo simulation technique are also presented to examine the estimation errors. [ABSTRACT FROM AUTHOR]

An important part of the knowledge required for designing the envelope of a new building is based on experience. Confronted with a building envelope design problem, a human expert adds to well-established domain knowledge his/her own experience or the experience of others, to support his/her reasoning process, and to guide him/her in stereotypical situations. Based on that observation, we can conclude that the building envelope design fits well the description associated with the so-called “weak theory domains”, and is a prime candidate for adopting a case-based reasoning (CBR) approach. Proposes strategies to encode, organize, and compare prototypical building envelope cases within a CBR framework for selecting the construction alternatives during the preliminary stage of the building envelope design. The methodology presented aims to find the most suitable design alternative for a new building envelope from a library of prototypical building cases. [ABSTRACT FROM AUTHOR]

A full-scale wood frame test hut with nine wall specimens, typical of low-rise residential construction in the province of Quebec, was built inside an environmental chamber. This test hut was subjected to 66 days of simulated winter and 47 days of late spring climatic conditions to verify the feasibility of different methods of mapping and representing graphically air exfiltration. Through a better understanding of the movement of air through the envelope, the risks related to moisture condensation within the envelope for different wall compositions can be better ascertained. The air leakage pattern characterization methods implemented were two-dimensional grid moisture content monitoring and three-dimensional grid temperature monitoring. The moisture content and temperature data were presented in a graphic form, using isohygrons and isotherms. Temperatures without the impact of air leakage were also calculated using a three-dimensional conductive heat transfer model. The air leakage pattern characterization methods and the resulting moisture and temperature maps are presented and discussed herein. [ABSTRACT FROM PUBLISHER]

During the detailed design stage of a building project, a vast amount of mostly interrelated design information is generated and communicated among specialists from several disciplines. Changes in some design information are inevitable due to the iterative nature of the design process. In many cases, when the design of a building component is modified by one discipline, this change affects the design of many related building components that are the responsibility of several other design disciplines. Commitment and resources are needed to accommodate such design changes to maintain compatibility among all the design information. Otherwise, incompatibility errors become embedded in the design information leading to numerous problems during the construction of the project. This paper presents a computer-assisted methodology that helps design managers in planning and scheduling changes with interrelated effects on the design information. [ABSTRACT FROM AUTHOR]

A laboratory test using a large-scale environmental chamber has been carried out on two flat roof models fully insulated with cellulose fiber. These two models represent the most representative single-cavity flat roofs, built in Montreal between 1930 and 1970, being insulated as part of an energy conservation program. The insulating strategy consists of packing cellulose fiber in the cavity. The goal of the test program was to determine the risk of rotting of the wood structure and moisture accumulation in the roof assembly. The test was performed using real-scale huts that were exposed to 6 months of winter and summer conditions. Two roof assemblies were each divided into five roof cavities. The main variables were the mode of moisture transfer (diffusion only and diffusion combined with air exfiltration), type of vapor barrier, and air leakage paths. The construction of the huts and the monitoring plan are described. The results of the 6-month test program using seven simulated climatic conditions are presented. Wetting and drying curves for different parts of the assemblies as well as the levels of exposure to moisture are presented and analyzed. [ABSTRACT FROM AUTHOR]

Many failures in the building envelope are associated with disintegration of the brick veneer. The evaluation of durability is important for proper selection of the brick. The American and the Canadian standard methods for evaluating the durability of brick are time consuming and involve destructive testing. As a result, limited tests are carried out on the bricks during selection, leaving uncertainty about their durability and performance. Nondestructive testing would reduce the time and cost of evaluation. Therefore, a study was undertaken to investigate the feasibility of using nondestructive testing methods for evaluating the properties of bricks and thereby possibly their durability. The ultrasonic pulse velocity method was selected for the study. Based on the study, new durability provisions were derived using the pulse velocity to identify durable and nondurable bricks. These provisions were validated using a different set of bricks. At this stage, the new provisions can be used only along with the ASTM method, but it can avoid the time-consuming ASTM procedure in many cases. [ABSTRACT FROM AUTHOR]