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Thermal insulation plays an important role in achieving building efficiency. Many engineering investigations were carried out to determine the optimum insulation thickness. In this paper, a coupled heat and moisture transfer model is presented to calculate the annual energy consumption. Then, the lifecycle total cost is analyzed by the P1-P2 economic model. Based on lifecycle total cost analysis, the optimum insulation thickness is determined. Three representative cities, viz. Changsha, Chengdu and Shaoguan, are chosen as the sample cities. The optimum insulation thickness, lifecycle saving and payback period are estimated. The results show that the optimum thickness of extruded polystyrene (XPS) is between 0.053 and 0.069m and the optimum thickness of expanded polystyrene (EPS) is between 0.081 and 0.105m. The maximum lifecycle saving varies from 16.60 to 28.50$/m2 and the payback period varies from 1.89 to 2.56 years. EPS is more economical than XPS as insulation because of its lower lifecycle total cost. [ABSTRACT FROM AUTHOR]

With air-tight housing construction becoming common practice in Canada the importance of providing fresh-air to interior spaces has never been greater. Fixed-plate cross-flow air-to-air heat/energy exchangers are utilized extensively across Canada; however limitations still exist for northern Arctic regions. This paper presents preliminary performance results pertaining to the use of water-vapour permeable cores in fixed-plate cross-flow air-to-air heat/energy exchangers for net-zero energy homes located in Arctic regions. Experimental tests were conducted with the use of a purpose built experimental setup where inlet supply and exhaust air conditions are controlled. The results and conclusions will aide in the design and evaluation of a heat/energy exchanger for Arctic regions to be completed in future work. [ABSTRACT FROM AUTHOR]

The Analysis of Variances (ANOVA) approach is used to quantify the impact of nine curtain wall design parameters on the energy consumption of an office space in the perimeter zone of a typical office building in Montreal. The uncertainty analysis shows that the variation in curtain wall configurations has generally a greater impact on the cooling followed by heating, lighting and total energy consumption. The global sensitivity analysis shows that the window wall ratio is the most significant design parameter influencing the end-use energy consumption. [ABSTRACT FROM AUTHOR]

Arctic homes are based on standards developed for the southern regions despite northern Canada's unique challenges. A performance protocol that integrates the building envelope with other subsystems meant to optimize energy efficiency, durability and project delivery should improve housing standards for the region. The protocol presented in this paper includes key standards, guidelines, criteria and verification methods that are to be met through the design, construction and operational stages. The protocol will anticipate and address key related challenges of the region to promote a delivery system that involves all stakeholders, reduces delays and cost overruns by developing key sets of parameters needed for energy efficient homes. This paper focuses on the development and content of the protocol. [ABSTRACT FROM AUTHOR]

The moisture buffering potential is defined as the capacity of hygroscopic materials to absorb and release moisture under cyclic moisture loads. In a large-scale experimental investigation, the authors found a significant difference in the moisture buffering potential and the moisture residual between wood paneling and gypsum board when subjected to different moisture load profiles. This difference is attributed to the different moisture capacity and vapor permeability of these two finishing materials. A further study, motivated by these observations, was carried out by the authors to investigate the impact of different moisture load profiles and the effect of moisture history on the moisture buffering potential through hygrothermal simulations. Ten hygroscopic materials are categorized into three groups based on their moisture capacity and vapor permeability. The moisture buffering potential of these three material groups were investigated under different moisture load profiles. The moisture residual in the first daily moisture load cycle was studied as well. The simulation results verify that the different response of these materials to the moisture load was determined by the materials' moisture capacity and vapor permeability, i.e. moisture effusivity, and material thickness. In addition, the moisture residual phenomenon is related to the penetration depth of materials. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a study of the effect of key design parameters on energy performance of two-storey single family dwellings and small scale neighborhoods, in a mid-latitude northern climate. Design parameters include the geometric shapes of dwelling units and their assemblage in a neighborhood. The effects of the design parameters are presented in a matrix that relates design parameters to performance criteria. An example for an evaluation system of the performance of design alternatives is proposed, based on design parameter effects and weights assigned to different performance criteria. Performance criteria considered are heating and cooling energy consumptions, solar energy generation, and shift of peak of electricity generation. The evaluation system is a decision-aiding tool, which enables selection of design parameter values leading to optimal performance for the assumed performance criteria. A design methodology is proposed for the design of solar optimized housing units and neighborhoods, based on the matrix of results and the evaluation system. [Copyright &y& Elsevier]

Abstract: To model the indoor environment influenced by room factors including moisture loads and ventilation conditions, the governing equations of heat, air and moisture (HAM) transport inside the room and through the envelope, including the coupling process of the interaction of heat and moisture between indoor air and envelope, need to be solved. This paper presents a CFD model of the indoor environment that takes into account the heat and moisture transfer through the envelope in a single simulation environment. The comparisons between experimental data and simulation results show close agreement. This model is then implemented in 12 cases to study the influence of moisture loads, ventilation rates, and positions of the air inlet and outlet on the indoor environment and on the heat and moisture transport through the envelope. Simulation results show that the humidity responses of the test room vary significantly for different moisture loads from 42g/h to 91g/h and for different ventilation rates from 0.5 air change per hour (ach) to 1ach. Changing the positions of the ventilation vents alters the air flow pattern significantly, thus affecting the ventilation efficiency. With a heat and moisture source inside the test room, the changed ventilation efficiency influences the indoor environment significantly, especially under low ventilation rates. The increased ventilation rate carries away more heat and moisture, which reduces both temperature and moisture levels inside the room. Under the mixed convection condition, the indoor temperature and moisture levels dominate the heat and moisture transport through the wall system. [Copyright &y& Elsevier]

Abstract: The concept of moisture buffering value based on material level tests has been widely adopted in current room level moisture buffering studies. However, the characterization of the material buffering properties may not be directly representative of the material buffering performance at room level because the room factors influence the moisture behavior of the materials. The moisture buffering is a dynamic moisture interaction process between the indoor humidity air and the hygroscopic finishing materials. The buffering effect is the amount by which the variation of the indoor humidity is dampened both by the hygroscopic materials and by the room factors. Hence, the magnitude of the buffering effect is related to the characteristics of the building structure. This paper presents an experimental study on the moisture buffering performance of wood paneling at room level and its buffering effects on the indoor environment. The data presented include the buffering effect values of several test scenarios on a full scale test hut in a large-scale environmental chamber. The data analysis shows that the moisture response of the hygroscopic material at room level varies in different test scenarios. This variation is influenced by room factors, including ventilation conditions and the amount of moisture generation, and to a lesser degree by the indoor initial humidity conditions. Hence, the buffering effect cannot be predicted based on the material performance alone. [Copyright &y& Elsevier]

Abstract: Moisture buffering (MB) phenomena exhibited by hygroscopic materials, such as interior finishing or furnishing, can reduce indoor humidity variation, thus improving indoor conditions and save energy consumed by the mechanical system for humidification or dehumidification. In full-scale experiments, the moisture buffering effect for an entire room is typically evaluated by the reduction of indoor relative humidity (RH) variation. In this study, a new approach to quantitatively evaluate the moisture buffering capacity of hygroscopic materials, namely the maximum accumulated moisture buffering value (MAMBV), is developed based on the moisture balance established in a full-scale experimental investigation. This value represents the maximum amount of moisture buffered by the hygroscopic materials. The impact of ventilation rate, moisture generation protocol, and addition of furniture on two types of interior surface materials, i.e. uncoated gypsum board and wood paneling, are evaluated using the MAMBV index. [Copyright &y& Elsevier]

Abstract: The capacity of drying out moisture accumulated within stud cavities, especially moisture due to rain penetration, is an important characteristic affecting the performance and durability of building envelope systems. This paper introduces a new approach for evaluating such drying performance based on the concepts and procedures of Limit State Design (LSD) used in structural engineering. For a well performing envelope, the moisture load must be less than the drying capacity of the system. The drying capacities are obtained through full-scale experiments that utilize moisture loading derived from a moisture source (water tray) placed at the bottom of the stud cavity. In moving out of the cavity, part of the moisture will be absorbed by the materials surrounding the stud cavity. When any part of the wall specimen reaches 20% MC, the cumulative evaporation from the water tray is termed as the ICEA (in-cavity evaporation allowance) of that wall system. The ICEA value is dependent on the envelope configuration and is a good indicator of the drying performance of that wall system. By comparing ICEA values of wall systems with their respective moisture loads, those envelopes having ICEA values higher than the amount of rain penetration calculated from prevailing driving rain and faults in the envelope are deemed to have adequate drying capacity. [ABSTRACT FROM AUTHOR]

Abstract: Although moisture significantly affects the performance and durability of building envelope systems, effective methods to quantify the relative drying capacity of these systems are yet to be developed. A new testing method and an evaluation approach for comparing the drying capacity of wood-frame wall systems in evacuating water due to rain penetration in the stud cavities are presented in this paper. A controllable and consistent moisture loading is created by placing a water tray on a load cell at the bottom of the stud cavity of the wall assembly which is then subjected to lab generated indoor/outdoor conditions. The data on water evaporation from water trays and the monitored moisture accumulations in the materials surrounding the stud cavities are used to establish load–response relations. Using these relations the relative performance of various building envelope systems in preventing biodeterioration caused by rainwater penetration into the stud cavities can be compared. The concept of in-cavity evaporation allowance (ICEA) has been proposed and it is based on the limit of 20% moisture content (MC) being reached at any location of the building envelope. [Copyright &y& Elsevier]

Abstract: An experimental project was conducted to investigate mold products, namely spores and volatile organic compounds (VOCs) in the cavity of full-scale stud wall assemblies. Twenty specimens were constructed and tested to inquire the capacity of wall cavities to restrain mold products, emanating from studs with 10% of their surface covered with mold, from penetrating into the indoor space. The tests were designed primarily to study the movement of spores. The project was subsequently extended to investigate the identification of microbial volatile organic compounds (MVOCs) and their transport through the building envelope. This paper presents the experimental design, testing procedure and a summary of the analysis conducted to identify mold related VOCs and their transport from the cavity to the indoor space, and the evaluation of the influence of experimental factors on this transport. Six experimental factors were investigated: air leakage path; mold presence; wall construction configurations (insulation, vapor barrier and sheathing material) and ambient conditions (dry and wet conditions). The chemical analysis of VOCs (volatile organic compounds) was performed using gas chromatography/mass spectrometry (GC/MS). Results are analyzed using multiple regression analysis to identify the mold related VOCs, and to determine the transport through the building envelope. Five VOCs are confirmed to be related to the mold presence in the cavity and the transport of these MVOCs is supported by the data. However, no significant effect of the construction factors on MVOC transport is detected. [Copyright &y& Elsevier]

Abstract: A research project was undertaken on full-scale wood-framed wall assemblies to evaluate the transport of mold spores from slightly moldy wood studs within the stud cavity to the indoor environment. A series of tests were performed with variations of such parameters as rates and patterns of air leakage, presence or absence of insulation and vapor barrier. Wood studs with slightly visible surface molds (10% of surface area) were used for some of the wall assemblies, while clear studs were used for the remainder. A pressurization setup was used to create an air infiltration through the wall assemblies. Air samples were taken to measure the spore concentrations in the stud cavities, infiltrating air, and laboratory background. Statistical significance testing methods were used to draw observations and conclusions from these data. The results from this experiment do not support a statistically significant increase of spore movement out of stud cavities into the indoor space due to the use of slightly moldy studs in the wall assemblies. [Copyright &y& Elsevier]

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]

Metal curtain walls typically have a large portion of continuous glazing area. In cold climate, the cold draft induced by the large cold glazing surface may cause discomfort to occupants seated in the perimeter zone. This paper presents the experimental investigation of the characteristics of the cold draft induced by two different types of glazing panels and its effect on the occupant''s local thermal sensation. A large-scale (3.8 m×6.7 m) metal curtain wall specimen consisting of two different wall systems was tested in an Environmental Chamber. The effect of the thermal performance of glazing units, the frame projection, and the mechanical ventilator on the cold draft was studied.The measurements indicate that the better-insulated glazing unit reduces the cold draft considerably compared to the conventional glazing unit, thus increasing the comfort level of the occupants. The frame projection deflects the cold flow from the wall surface and causes mixing of the cold air with the room air thus elevating the temperature and decreasing the momentum of the cold air before it penetrates into the occupied zone. The mechanical ventilator, located at the end of the room side, simulates the design of moving the heating supply away from the exterior wall. The measurements show that the resultant air movement from the ventilator increases the draft risks at ankle level for the occupants, and the ASHRAE requirements cannot be met until the occupants seat 2 m away from the wall. The analysis shows that, for the test conditions of this study, the glazing surface temperature of both wall systems needs to be raised, through perimeter heating or ventilation system for example, in order to provide a comfortable indoor climate, the need for the better-insulated system being less than the conventional system. [Copyright &y& Elsevier]