Michael Lacasse

National Research Council Canada | NRC · Institute for Research in Construction (IRC)

Climate heat waves occurring in urban centers are a serious threat to public health and wellbeing. Historically, most heat-related mortalities have arisen from excessive overheating of building interiors housing older occupants. This paper developed an approach that combines the results from building simulation and bioheat models to generate health...

Quantifying building resilience to extreme weather conditions helps identify the capability of a building system to tolerate disturbances and recover from extreme events. The robustness of building retrofit strategies can also be evaluated through their contributions to building resilience. In this study, building thermal resilience to summertime h...

Facade failures due to rainwater entry are common in Turkey although, few systematic studies have been completed to determine the types of defects and failures and their causes as would permit developing appropriate repair solutions. The intent of this study is to determine the types of defects and failures caused by rainwater ingress to building f...

Mould may grow in wood frame wall assemblies when subjected to excessive moisture load over prolonged periods of time. To permit estimating the moisture risk in wood-frame wall assemblies, one approach is to use hygrothermal simulations. This process requires access to relevant climate data and as well, knowledge and experience regarding the use of...

Canada employs a prescriptive-based code for residential buildings. The minimum requirements as prescribed in the 2015 National Building Code were developed based on historical climate which was assumed static. It is now evident that the climate is changing and it is anticipated that wind-driven rain events will be more frequent, of longer duration...

Drainage reduces the amount of water able to infiltrate toward the interior of wall assemblies. However, a portion of the infiltrated water remains in the assembly after drainage has occurred. The degree to which this retained portion of water affects the durability of the wall assembly can be evaluated by means of hygrothermal simulations. However...

Under heat-stressful conditions, occupants can adapt to the environment by regulating sweating or blood flow to the surface of the skin. However, the ability of the human body thermoregulation declines with age due to age-related physiological and thermoregulatory changes such as the delay in vasodilation and sweating and lower metabolism. Therefor...

In this study, a comparison is made of overheating in multiple field-monitored buildings using several different overheating indices, including dry-bulb temperature, the heat index (HI), humidex (H), standard effective temperature (SET), wet-bulb globe temperature (WBGT), discomfort index (DI), and summer simmer index (SSI). The field monitoring wa...

The objective of this research is to investigate the effects of different bias correction (BC) methods applied to climate data used to assess the hygrothermal performance on building envelopes based on simulations. To this end, a univariate and two multivariate distribution based bias correction methods were used to prepare weather files to assess...

The objective of this study was to develop a prediction model for predicting the mould growth risk in wood-frame walls. A machine learning algorithm, the Partial Least Squares (PLS) regression was used for developing the model. Hygrothermal simulations were performed for a wood-frame wall with brick cladding using hourly historical and projected fu...

This study explores the spatial variability of the thermal responses of older occupants' in indoor environments at various locations in Montreal, Canada. Urban climate in and around the city over an extreme heat event in 2018 is simulated at 1 km spatial resolution using Weather Research and Forecasting (WRF) model, and data for 29 long-term care b...

Defining and quantifying building thermal resilience is important given that this helps determine the capability of a building system to tolerate disturbances from exposure to extreme heat events, and from which to compare different retrofit strategies to enhance the robustness of a building system to such events, and as well, to estimate the rapid...

For an efficient moisture performance analysis of walls, the selection of wall orientation for undertaking the hygrothermal simulations plays an important role. The wall orientation receiving the highest amount of annual wind-driven rain (WDR) and the one receiving the least annual solar radiation is that which is recommended in ASHRAE 160. There a...

Canada is warming at double the rate of the global average caused in part to a fast-growing population and large land transformations, where urban surfaces contribute significantly to the urban heat island (UHI) phenomenon. The federal government released the strengthened climate plan in 2020, which emphasizes using nature-based solutions (NBSs) to...

To assess the impact of future climate on the hygrothermal performance of walls when considering different types of walls, geographical locations, and various climate change scenarios, a significant number of simulations will be required. To address this issue and thereby reduce the number of simulations and calculation time, regression models can...

In this study, the spatial distribution of the urban climate is evaluated and its impact on indoor overheating conditions is assessed. This was done by modelling the near-field climate of Ottawa and Montreal at 1 km resolution for the summer of 2018 during which an extreme heat event occurred causing nearly 100 deaths in this area. The climate data...

Building models that can accurately predict hourly indoor air temperatures in free-running situations are key to understanding overheating conditions and the resilience of passive cooling strategies under a changing climate. To accurately predict indoor temperatures it is necessary to properly model pressure-driven infiltration and natural ventilat...

Due to age-related physiological changes, older people are more vulnerable than young people to heat or cold conditions. Predicting older people's thermal sensations is essential for controlling the built environment and avoiding extreme heat/cold injuries. Previous studies mainly focused on predicting the thermal sensation of young people, and the...

Climate change will continue to bring about unprecedented climate extremes in the future, and buildings and infrastructure will be exposed to such conditions. To ensure that new and existing buildings deliver satisfactory performance over their design lives, their performance under current and future projected climates needs to be assessed by under...

Climate change has led to prolonged, more frequent, intense, and severe extreme weather events, such as summertime heatwaves, creating many challenges on the economy and society and human health and energy resources. For example, the 2010 and 2018 heatwave in Quebec, Canada, resulted in about 280 and 93 heat-related deaths, and there were around 50...

Physiological modeling is important to evaluate the effects of heat and cold conditions on people’s thermal comfort and health. Experimental studies have found that older people (above 65 year old) undergo age-related weakening changes in their physiology and thermoregulatory activities, which makes them more vulnerable to heat or cold exposure tha...

In the last decades, considerable work has been done regarding service life prediction of buildings and building components. Academics and members of the CIB W080 commission, as well as of ISO TC 59/SC14, have made several efforts in this area and created a general terminology for the concept of service life, which is extremely relevant for propert...

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...

One of the parameters that influences the moisture performance of the wood framed wall assembly is the material properties of exterior cladding. The uncertainties of its properties, would result in a range of wall performance. The objective of this study was to investigate the impact of uncertainties in cladding material properties on moisture perf...

Due to global climate change, the world has been experiencing significant increases in average temperatures and the frequency and intensity of extreme weather events such as heatwaves. The overheating problem in indoor spaces of buildings has become a concern to the comfort and health of building occupants, especially vulnerable populations such as...

This study demonstrates the importance of high-resolution climate simulations when conducting city-scale outdoor heat wave alert and indoor overheating assessments. This is done by modelling urban climate of the Ottawa and Montreal cities at 1 km and 25 km, typical for regional climate modelling respectively, over the summer of 2018 when an extreme...

A moisture reference year (MRY) is generally used to assess the durability, or long-term performance of building envelopes within a long climatological time period, e.g. a 31 year timeframe. The intent of this paper is to develop a set of moisture reference years that can be used to assess risk to the formation of mould growth in wood-frame buildin...

Hygrothermal simulations can be used as a reliable tool in analysing moisture performance. For an efficient analysis, it is important to appropriately select the wall orientation in the simulations. ASHRAE 160 recommends to using orientation with highest amount of annual wind-driven rain (WDR) and the orientation with the least annual solar radiati...

This paper evaluates the reliability of the currently used climate-based indices in selecting a moisture reference year (MRY) for the freeze-thaw (FT) damage risk assessment of internally insulated solid brick walls. The evaluation methodology compares the ranking of the years determined by the climate-based indices and response-based indices from...

Parts of the building envelope that frequently receive high amounts of rain are usually exposed to a higher risk of deterioration due to moisture. Determination of such locations can thus help with the assessment of moisture-induced damage risks. This study performs computational fluid dynamics (CFD) simulations of wind-driven rain (WDR) on the Par...

As a consequence of global warming and rapid urbanization around the globe, the magnitudes and frequencies of extreme heat events (EHEs) are increasing and this trend is expected to continue into the future. In this study, the added benefit of modelling climate at convection-permitting spatial resolutions (grid spacing < 4 km) is considered for a s...

When assessing a building performance under overheating conditions, there is a need to identify extreme hot years (EHYs) for a given climate location. Different types of EHYs can be selected depending on the criteria for their selection, such as long, intense, or severe heatwaves defined based on dry-bulb temperature and other thermal comfort indic...

Hygrothermal simulations can be used to evaluate the hygrothermal response of building envelope to the effect of climate change. However, to account for the uncertainty in projected future climates, a large number of simulations are required. To reduce computational time, hygrothermal performance of walls is typically evaluated using Moisture Refer...

Air-barrier systems (ABSs) are essential elements in the performance of building envelopes and they are specified in the National Building Code of Canada (NBC) to minimize the infiltration and exfiltration of air through the building envelope to control the risk of condensation. Although their primary function is to control the movement of air acro...

Climate change is a major contributor to extreme heat events, which have been a threat to the health of building occupants. It has been found that the rates of mortality and morbidity are much higher for urban dwellers during prolonged periods of elevated outdoor temperature. However, only limited studies have been conducted on the current overheat...

Previous studies have shown that the effects of climate change on building structures will increase the mould growth risk of the wood-frame building envelope in many circumstances. This risk can be controlled by wind-driven rain deflection, improving water tightness of the exterior facade, and improving cladding ventilation. However, the effectiven...

The two-node bioheat model is widely used in thermal comfort standards and design tools. In recent years, there have been many new experimental studies and thermoregulatory models developed under stressful heat or cold conditions, but those have not been tested under the two-node model structure. Furthermore, limited validation studies of the two-n...

The performance and durability of wall assemblies are greatly affected by the moisture load to which they may be subjected, in particular those arising from Wind-Driven Rain (WDR). Standard approaches for estimating such moisture loads assume 1% of the WDR load, whereas these loads have also been assessed from watertightness tests, although these a...

The objective of this study was to explore the potential of a machine learning algorithm, the Support Vector Machine Regression (SVR), to forecast long-term hygrothermal responses and the moisture performance of light wood frame and massive timber walls. Hygrothermal simulations were performed using a 31-year long series of climate data in three ci...

As a consequence of global warming, buildings in Canada and around the globe are expected to face unprecedented climate over their design lives. The Moisture Index (MI) is a climate-based indicator currently used in the National Building Code of Canada (NBCC) to guide the design of wall assemblies for acceptable durability performance. In this stud...

The moisture load in wall assemblies is typically considered as 1% of the Wind Driving Rain (WDR) load that is deposited on the surface of wall assemblies as specified in the ASHRAE-160 standard whereas this ratio has been shown to be inaccurate as compared to results derived from several watertightness tests. Accurate assessment of moisture loads...

The objective of this work was to compare the hygrothermal responses and the moisture performance of four wood-frame walls as predicted by four hygrothermal (HAM) simulation tools, namely: DELPHIN, WUFI, hygIRC and COMSOL. The four wall systems differ only in their cladding type; these were fibreboard, vinyl, stucco and brick. Three Canadian cities...

The objective of this study was to assess the potential effects of climate change on the moisture performance and durability of massive timber walls on the basis of results derived from hygrothermal simulations. One-dimensional simulations were run using DELPHIN 5.9.4 for 31 consecutive years of the 15 realizations of the modeled historical (1986–2...

In the face of rapid urbanization and global warming, it is important to acquire a better understanding of urban climate and land-atmosphere interactions operating therein. The Weather Research and Forecasting (WRF) model is a limited area model that has been used to study urban microclimate in many cities across the globe. However, such a study is...

This paper presents the results of a Guarded Hot Box (GHB) experiment on a wall assembly made up of both steel stud framing and an external insulating assembly which incorporates vacuum insulation panels (VIPs) for which knowledge of the composition of the VIP barrier foil is not readily available. The purpose of the tests is to provide an experime...

The purpose of this paper is to investigate the potential for calculation methods to determine the thermal resistance of a wall system containing vacuum insulation panels (VIPs) that has been experimentally characterised using a guarded hot box (GHB) apparatus. The VIPs used in the wall assembly have not been characterised separately to the wall as...

In this study, a 1 km resolution Weather Research and Forecasting (WRF) model is developed for the Montreal city and validated by field monitored data. The validated model will be used to dynamically downscale future projections of climate made around the city to evaluate the overheating conditions based on building energy simulations. The indoor t...

Today, it is globally known that climate change needs to be addressed to mitigate its harmful effects on our environment. It is also common knowledge that the contribution of historical buildings to the energy consumption of the existing Canadian building stock is severe. Buildings of historical identity are often poorly thermally insulated. Thus,...

Hygrothermal simulations are necessary to permit analyzing moisture performance when designing building envelopes. Owing to the high computing time and cost of the long term simulations, a common approach is to select representative year(s), the Moisture Reference Year(s), from a long-term series of climate data. It is assumed that the use of Moist...

Given the long lifespan of buildings it becomes inevitable to assess the impact of climate change when designing building envelopes or retrofitting solutions. Hygrothermal simulations would benefit from using a climate ensemble to account for the large uncertainties that come with modelled climate data. However, this has been rarely done so far, an...

In 2018 Montreal experienced a severe heatwave (extreme heat event), causing 66 deaths, for which most of the deceased lived in buildings located in hot areas within the city and that had limited access to air-conditioning. To study the resiliency of buildings against extreme heat events (EHE), in particular within the context of the changing clima...

Overheating in built environments during climate extreme heat events is a major concern to human health, particularly for people vulnerable to prolonged exposure to heat and humidity. However, currently available methods for assessing the risk of overheating lack robust procedures to evaluate the effects of overheating on the comfort and health of...

Many building components rely on pressure equalization to achieve a good performance in respect to watertightness. Guidelines on geometrical constraints derived from numerical models and experiments are widely spread, but it appears these are only valid for dry conditions. To evaluate the impact of rain on the pressure equalization in facades, a ge...

Sustainable building practices are rooted in the need for reliable information on the long-term performance of building materials; specifically, the expected service-life of building materials, components, and assemblies. This need is ever more evident given the anticipated effects of climate change on the built environment and the many governmenta...