Effects of climate change on the moisture performance and durability of brick veneer walls of wood frame construction in Canada

The objective of this study was to assess the potential effects of climate change on the moisture performance and durability of red matt clay brick veneer walls of wood frame construction on the basis of results derived from hygrothermal simulations. One-dimensional simulations were run using DELPHIN 5.9 for selected moisture reference years of the 15 realizations of modelled historical (H: 1986-2016) and future (F: 2062-2092) climate data of 12 Canadian cities. The mold growth index at the outer layer of the OSB sheathing panel was used to compare the moisture performance under H and F periods. Results for the base design that meet the minimum requirements of the National Building Code of Canada showed that cities within the interior of the country, characterized by a low annual rainfall, are less likely to develop significant mold growth under H and F periods, whereas cities in coastal areas, characterized by high annual rainfall, present a heightened risk to mold growth under both H and F periods. For cities located on the west coast, a possible solution could be to use a 38-mm ventilated drainage cavity as this measure would help dissipate moisture from within the cavity. On the east coast, apart from using a 38-mm ventilated drainage cavity, other measures aiming at reducing the wind-driven rain deposition (i.e., increasing overhang ratio or the height of the roof) could be introduced. However, the feasibility of such measures needs to be considered in respect to whether these are to be implemented as part of a new building or retrofit of an existing one.

The Influence of Cavity Ventilation on the Performance of Brick Veneer Panels When Exposed to Wind Driven Rain: an Experimental Analysis

This study investigates the influence of cavity ventilation on the wind driven rain (WDR) performance of brick veneer walls. Two types of walls (type C and D) both bonded with N-type mortar were studied. The volume and frequency of WDR was based on weather station data from York University. Cavity conditions were mocked with a cavity chamber and ventilation was simulated with a fan providing air suction out of the cavity. Ventilation rates were simulated at 0, 5 and 10 ACH. Higher ventilation rates resulted in more efficient drying and lower RH within the cavity chamber. Wall type C exhibited more absorption with increased ventilation rates. Moisture content readings were generally irrelevant due to failure of the prescribed method. Measuring the influence of cavity ventilation on the amount of penetrated water should be further investigated by applying different ventilation rates to the same wall specimens to reduce the impact of physical variations within the same brick type.

The Influence of Cavity Ventilation on the Performance of Brick Veneer Panels When Exposed to Wind Driven Rain: an Experimental Analysis

This study investigates the influence of cavity ventilation on the wind driven rain (WDR) performance of brick veneer walls. Two types of walls (type C and D) both bonded with N-type mortar were studied. The volume and frequency of WDR was based on weather station data from York University. Cavity conditions were mocked with a cavity chamber and ventilation was simulated with a fan providing air suction out of the cavity. Ventilation rates were simulated at 0, 5 and 10 ACH. Higher ventilation rates resulted in more efficient drying and lower RH within the cavity chamber. Wall type C exhibited more absorption with increased ventilation rates. Moisture content readings were generally irrelevant due to failure of the prescribed method. Measuring the influence of cavity ventilation on the amount of penetrated water should be further investigated by applying different ventilation rates to the same wall specimens to reduce the impact of physical variations within the same brick type.

Alternative Method to the Replication of Wind Effects into the Buildings Thermal Simulation

To design energy-efficient buildings, energy assessment programs need to be developed for determining the inside air temperature, so that thermal comfort of the occupant can be sustained. The internal temperatures could be calculated through computational fluid dynamics (CFD) analysis; however, miniscule time steps (seconds and milliseconds) are used by a long-term simulation (i.e., weeks, months) that require excessive time for computing wind effects results even for high-performance personal computers. This paper examines a new method, wherein the wind effect surrounding the buildings is integrated with the external air temperature to facilitate wind simulation in building analysis over long periods. This was done with the help of an equivalent temperature (known as Tnatural), where the convection heat loss is produced in an equal capacity by this air temperature and by the built-in wind effects. Subsequently, this new external air temperature Tnatural can be used to calculate the internal air temperature. Upon inclusion of wind effects, above 90% of the results were found to be within 0–3 °C of the perceived temperatures compared to the real data (99% for insulated cavity brick (InsCB), 91% for cavity brick (CB), 93% for insulated reverse brick veneer (InsRBV) and 94% for insulated brick veneer (InsBV) modules). However, a decline of 83–88% was observed in the results after ignoring the wind effects. Hence, the presence of wind effects holds greater importance in correct simulation of the thermal performance of the modules. Moreover, the simulation time will expectedly reduce to below 1% of the original simulation time.

The Significance of Sky Temperature in the Assessment of the Thermal Performance of Buildings

Energy-efficient building design needs an accurate way to estimate temperature inside the building which facilitates the calculation of heating and cooling energy requirements in order to achieve appropriate thermal comfort for occupants. Sky temperature is an important factor for any building assessment tool which needs to be precisely determined for accurate estimation of the energy requirement. Many building simulation tools have been used to calculate building thermal performance such as Autodesk Computational Fluid Dynamics (CFD) software, which can be used to calculate building internal air temperature but requires sky temperature as a key input factor for the simulation. Real data obtained from real-sized house modules located at University of Newcastle, Australia (southern hemisphere), were used to find the impact of different sky temperatures on the building’s thermal performance using CFD simulation. Various sky temperatures were considered to determine the accurate response which aligns with a real trend of buildings’ internal air temperature. It was found that the internal air temperature in a building keeps either rising or decreasing if higher or lower sky temperature is chosen. This significantly decreases the accuracy of the simulation. It was found that using the right sky temperature values for each module, Cavity Brick Module (CB) Insulated Cavity Brick Module (InsCB), Insulated Brick Veneer Module (InsBV) and Insulated Reverse Brick Veneer Module (InsRBV), will result in 6.5%, 7.1%, 6.2% and 6.4% error correspondingly compared with the real data. These errors mainly refer to the simulation error. On the other hand using higher sky temperatures by +10 °C will significantly increase the simulation error to 16.5%, 17.5%, 17.1% and 16.8% and lower sky temperature by +10 °C will also increase the error to 19.3%, 22.6%, 21.9% and 19.1% for CB, InsCB, InsBV and InsRBV modules, respectively.

Modelling moisture conditions behind brick veneer cladding: Verification of common approaches by field measurements

Cavity walls consisting of an outer leaf, a cavity and an inner leaf are a widespread building enclosure configuration because of their good performance regarding rain tightness. To increase the drying potential, open head joints are typically provided in the brick outer leaf, creating cavity ventilation. Even though this cavity ventilation has a limited effect on the drying out of the brick veneer, it can significantly reduce the moisture levels inside the cavity. This might be crucial when the brick veneer is combined with, for example, a wooden load-bearing wall. A reliable prediction of the cavity moisture levels is hence essential. However, previous studies showed that the ventilation rate in the cavity is highly fluctuating in both magnitude and direction. That is why most numerical models simplify cavity ventilation by neglecting it, replacing it by an equivalent resistance, assuming a constant air change rate and so on. This article verifies common assumptions in numerical models to incorporate cavity ventilation behind a brick veneer cladding, by confronting the simulations with detailed field studies. The results showed that for walls exposed to driving rain and solar radiation, most simplified one-dimensional simulations do not suffice to predict the moisture content in the cavity in a reliable way. Only with two-dimensional simulations, incorporating the airflow in the cavity, a good agreement with the in situ measurements was obtained. Furthermore, the two-dimensional models showed to be able to capture the moisture gradient along with the height of the wall rather precisely.

EXPERIMENTAL INVESTIGATION OF PULL OUT STRENGTH OF FLEXIBLE TIES IN THIN BRICK VENEER LAYER

The use of thin brick veneer layers for building facades becomes more popular nowadays. Using thin bricks (50−65 mm thick) instead of normal 100−120 mm thick bricks let us to save expenses up to 50% related to materials. The connection of thin veneer layer with inner construction wall must be assured. Usually, the connection is fulfilled using flexible metal or composite ties. The main issue for this connection is tie pull out strength from thin brick masonry. This strength depends on type and construction of ties and it governs the number of ties need for facades. This article describes experimental research of pull out strength of flexible steel ties in thin brick masonry. Two possible anchoring types were used. Experimental test results and analysis are described in the article.

Hygrothermal performance of timber frame walls with brick veneer cladding: a parameter analysis

To meet the increasingly stringent energy efficiency requirements, the market share of timber frame houses is steadily growing across Europe. Timber frame walls in Belgium are typically combined with a brick veneer cladding, which has a high buffer capacity for wind driven rain and a relative low cavity ventilation rate. Consequently, moisture levels inside the cavity may become high, which might lead to an inward vapour flow and an elevated moisture content in the inner part of the wall. In combination with a moisture sensitive timber frame inner wall, this could result in an increased risk of fungal growth. Therefore, the aim of the current paper is to study the hygrothermal performance of timber frame walls with brick veneer cladding in a moderate sea climate. To do so, a field study on two typical timber frame walls with brick veneer cladding is conducted. The field study specifically focuses on the contradictory criterion for the vapour diffusion resistance of the wind barrier for summer and winter conditions. The data of the in-situ measuring campaign indicates that the differences between set-ups with wind barriers with different vapour diffusion resistance is rather limited. In addition, a parameter analysis is conducted using a numerical model. The parameter analysis indicates an increased mould growth risk due to the brick veneer cladding and the importance of providing hygroscopic moisture buffer capacity inside the wall.

A service life model of metal ties embedded in the mortar joints of brick veneer walls with applications to reinforced concrete

The issue regarding the corrosion of steel ties connecting brick veneer to a structural backing is well documented. In this paper, the predicted corrosion rate and resulting service life estimates, produced by a time-stepped service life model developed in Visual Basic for EXCEL, for metal ties embedded in mortar, are compared with the empirically determined corrosion rates and service lives of 16 zinc galvanized tie specimens taken from 13 buildings located in 6 different Canadian cities. This tie service life model, coined the “Tie Service Life Predictor”, correlates the external environment of the building to the tie life. As with most corrosion models for steel embedded in concrete (or mortar), the model is broken into two distinct phases: corrosion initiation using Fick’s law of diffusion and corrosion propagation. By considering the mortar surrounding the tie as the tie’s atmosphere, the Tie Service Life Predictor characterizes the microenvironment (atmospheric conditions) surrounding the tie from the macroenvironment conditions. Once the atmospheric conditions were established, the ISOCORRAG atmospheric corrosion model could be used to predict the corrosion rate of zinc galvanized steel ties embedded in the mortar joints of the exterior wythe of brick veneer wall systems. The methods used to create the Tie Service Life Predictor could also be applied to service life estimation of reinforcing steel in concrete structures such as bridge decks and parking structures.