Hua Ge | Concordia University (Canada) (original) (raw)
Papers by Hua Ge
Climate data is one of the most important inputs for hygrothermal simulations and significantly i... more Climate data is one of the most important inputs for hygrothermal simulations and significantly influences the simulation results that are used for moisture performance assessment of building envelopes. Conventionally, climate data from representative weather stations are used for hygrothermal simulations to assess the moisture performance of the buildings. Recently, the Construction Research Centre of the National Research Council Canada generated historical and future climate data for 564 locations across Canada. In this paper, the climate data of four urban locations within Vancouver (a humid and warm coastal city in Canada) were selected for hygrothermal simulations. These include an open area at the airport, a city center, an area surrounded by plants, and an area surrounded by a water body. The 31-year-long simulations were performed for a typical woodframe wall assembly complying with moisture protection designs as provided in the National Building Code Canada (NBCC 2020) but rain penetration was assumed considering the deficiency of exterior cladding. The differences in its hygrothermal response across the four locations were analyzed. It was found that some climate parameters are significantly different among the selected locations, although the values for moisture indices given in the NBCC 2020 for these locations are all similar. The results show that high values of WDR are the dominant factor that drives the moisture performance but there is no indication that the design of the assembly could be different among the tested locations.
E3S web of conferences, 2021
Canadian Journal of Civil Engineering, Nov 1, 2019
In terms of hygrothermal performance, solid wood panels such as cross-laminated timber (CLT) are ... more In terms of hygrothermal performance, solid wood panels such as cross-laminated timber (CLT) are sensitive to moisture. However, the previous studies on the hygrothermal performance of CLT external envelopes have not indicated the critical moisture conditions for CLT external walls. Therefore, our main objective was to set limit values as hygrothermal criteria for the design of CLT external walls in terms of moisture conditions using a stochastic approach to ensure safe hygrothermal performance. Hygrothermal performance was evaluated by simplified 1D validated calculation models based on the field measurements [1]. Peer-review under the responsibility of the organizing committee of the ICMB23.
Building Simulation, Mar 1, 2021
Building and Environment, Dec 1, 2018
As energy consumption has become an important issue in building design, most building codes requi... more As energy consumption has become an important issue in building design, most building codes require a higher insulation level for building envelopes to improve the building's energy efficiency. However, the highly insulated walls may lead to a higher risk of moisture problems. Although hygrothermal simulation has been widely used to investigate the moisture performance of wood framed walls, the uncertainties of input parameters such as material properties, boundary conditions and moisture loads, may lead to discrepancies between simulation results and actual performance of the envelope. This paper investigates the hygrothermal performance of highly insulated wood framed walls using a stochastic approach, which combines the Latin Hypercube Sampling method and Factorial Design to take into account the uncertainties of material properties, boundary conditions and moisture loads (air leakage and rain leakage). The investigated walls include an I-joist deep cavity wall, two exterior insulated walls, and a conventional 2x6 stud wall as the baseline. It is found that under the moisture loads introduced (i.e. air leakage and rain leakage), the exterior insulated walls have a lower mold growth risk than the deep cavity wall and the 2x6 stud baseline wall. The uncertainties of material properties do not result in significant variations in simulation results such as moisture content and mold growth index as uncertainties of moisture loads do. The hygrothermal performance of these highly insulated walls is more sensitive to moisture loads and the significance of the moisture loads (air leakage and rain leakage) depends on climatic conditions.
Buildings
In response to Canada’s commitment to reducing greenhouse gas emissions and to making pathways to... more In response to Canada’s commitment to reducing greenhouse gas emissions and to making pathways to achieve carbon neutral buildings, this paper presents two real case studies. The paper first outlines the potential of trees to absorb CO2 emissions through photosynthesis, and the methods used for the estimation of their annual carbon sequestration rates. The net annual carbon sequestration rate of 0.575 kgCO2eq/m2 of tree cover area is considered in our study. Then, this paper presents the carbon life cycle assessment of an all-electric laboratory at Concordia University and of a single-detached house, both located in Montreal. The life cycle assessment (LCA) calculations were performed using two software tools, One Click LCA and Athena Impact Estimator for Buildings. The results in terms of Global Warming Potential (GWP) over 60 years for the laboratory were found to be 83,521 kgCO2eq using One Click LCA, and 82,666 kgCO2eq using Athena. For the single-detached house that uses natura...
Healthy, Intelligent and Resilient Buildings and Urban Environments, 2018
Extreme cold climates and Canada's sparsely populated Northern regions have limited human and inf... more Extreme cold climates and Canada's sparsely populated Northern regions have limited human and infrastructural capacity making it difficult to build energy-efficient homes. Despite such differences, homes are built based on codes and standards developed for Canada's South. In 2008, a by-law was passed in Yellowknife, Canada requiring a minimum EnerGuide Housing (EGH) rating of 80 for all new single-family and two-family residential buildings. The EnerGuide's Energy Rating Service (ERS) program is an energy assessment program for residential housing formerly known as the EnerGuide Rating for Houses (EGH). Homes are rated between 0 to 100; lower numbers represent homes that are less efficient and 100 represents an airtight and well-insulated house that is net-zero energy. 1002 homes from the City of Yellowknife evaluated since 1950s were studied from the ERS database, Performance metrics studied include energy intensity, EGH rating, ACH rating, window types, the thermal resistance of the building envelope, primary heating and hot water heating equipment's efficiencies, total electricity used, and total energy used. The analysis identified the current state of housing in Yellowknife, past and present housing trends, and determined the effect of the city of Yellowknife's new building by-law had on housing performance. The preliminary finding shows a pathway to significantly improve the energy efficiency of the housing stock in Yellowknife. This regulation shows other municipalities in Canada that legislations pushing energy efficient buildings can be very effective.
Energy and Buildings, 2015
The existence of thermal bridges in building envelopes affects the energy performance of building... more The existence of thermal bridges in building envelopes affects the energy performance of buildings, their durability and occupants' thermal comfort. Typically the effect of thermal bridges on the energy performance is taken into account by implementing an equivalent U-value in 1D whole building energy simulation program. This treatment accounts for the effect of thermal bridges on the overall thermal transmittance, while their thermal inertia effect is ignored. The presence of thermal bridges not only reduces the overall thermal resistance but also changes the dynamic thermal characteristics of the envelope. This paper investigates the dynamic effect of thermal bridges on the energy performance of residential buildings through simulations. A two-story residential building is used as a case study. Three methods, namely equivalent U-value method, equivalent wall method, and direct 2D/3D modeling method, are implemented in WUFI Plus, a whole building Heat, Air and Moisture (HAM) modeling program. Simulations are carried out for two climates with different insulation levels. Simulation results show that for the cold climate the annual heating load of this building with the inclusion of thermal bridges modeled using 3D dynamic method is 8-13% higher than that modeled using the equivalent U-value method, and 4-9% higher than that modeled using the equivalent wall method. With the increase of the insulation level, the percentage effect of thermal bridges on the heating load increases, while the difference among the three methods decreases. For the hot climate, simulation results show that the presence of thermal bridges increases the annual cooling load by 20%. Compared to the 3D dynamic method, the annual cooling load is underestimated by 17% using the equivalent U-value method and by 14% using the equivalent wall method, respectively.
Buildings
The building sector is responsible for nearly 40% of the total global direct and indirect CO2 emi... more The building sector is responsible for nearly 40% of the total global direct and indirect CO2 emissions. Urban green infrastructure, which includes features such as urban trees, vegetation, green roofs, and green facades, are examples of nature-based solutions often employed as municipal climate mitigation and adaptation strategies. This approach offers a range of cost-effective strategies for reducing municipal CO2 emissions and presents compelling public policy co-benefits such as improved urban livability and enhanced environmental conditions. For municipalities to confidently deploy these solutions at a scale necessary to achieve climate benefits, acquiring knowledge of quantifiable and demonstrated outcomes is an essential requirement. The objectives of this paper are to (1) provide a comprehensive analysis of the advantages and limitations of nature-based solutions (NBS) to address the challenge of reducing CO2 emissions; (2) evaluate existing design guidelines and policies as...
Drying and wetting can occur locally at different parts of a building envelope and involve simult... more Drying and wetting can occur locally at different parts of a building envelope and involve simultaneous heat, air, and moisture transfer. These dynamic wetting and drying processes can be captured using advanced hygrothermal models. In this paper, the one-dimensional hygrothermal model HAMFit is used to simulate the dynamic hygrothermal responses of a sheathing board in a prefabricated wall system. The walls comprise the following layers: fiber-cement board as a cladding layer, plywood as a sheathing board, expanded polystyrene (EPS) as insulation, gypsum board as an interior layer, and 6 mil polyethylene sheet as a vapor and air barrier. The simulation results were compared with measured data from an experiment carried out at the field Building Envelope Test Facility, Building Science Centre of Excellence (BSCE), British Columbia Institute of Technology (BCIT). The model’s prediction, using the measured indoor and outdoor boundary conditions, of the transient temperature and moistu...
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2021
As the urban population grows and the global economy develops, municipal solid waste management (... more As the urban population grows and the global economy develops, municipal solid waste management (MSWM) has become an increasingly prominent global issue. MSWM is particularly difficult in developing countries due to its high cost and time-consuming nature. The Environment-based design (EBD) can potentially contribute to global MSWM by reducing costs and increasing efficiency, especially in helping developing countries identify critical issues in MSWM. This paper uses and demonstrates the effectiveness and efficiency of the EBD method to analyze and identify critical issues in MSWM, using the city of Nairobi as a case study. This paper contains the first two of EBD's three activities: environment analysis and conflict identification, during the design problem period, design knowledge, and design solutions simultaneously and interdependently evolve as a part of the environment. The comparison with the existing literature confirms that the conclusions reached are, to some extent, reliable, time-saving, and less costly, which will offer a possibility to solve the problem of MSWM in impoverished areas.
E3S Web of Conferences, 2020
With the anticipated increase in temperature and solar radiation and frequency of extreme weather... more With the anticipated increase in temperature and solar radiation and frequency of extreme weather conditions due to climate change, buildings typically designed/built in Canadian cold climates would experience increased risks of summer overheating. This paper focuses on how these existing buildings perform under a current extreme year and projected future climates. Results show that the thermal conditions of a single-family detached house built in 1964 and 1990 are more comfortable than the house built to meet the current National Energy Code of Canada for Buildings (NECB) and high energy-efficient building (HEEB) without including natural ventilation by up to 50%. On the other hand, when natural ventilation is included, the house built to NECB and HEED are more comfortable. Sensitivity analysis is carried out to evaluate the influence of five design parameters, i.e. wall and roof insulation, airtightness, U-value and SHGC of windows. Sensitivity analysis shows that wall insulation,...
MATEC Web of Conferences, 2019
Buildings now produce more than a third of global greenhouse gases, making them more than any oth... more Buildings now produce more than a third of global greenhouse gases, making them more than any other sector contributing to climate change. This paper investigates the effect of climate change on the energy performance and thermal comfort of a high-rise residential building with different energy characteristic levels, i.e. bylaw to meet current National Energy Code of Canada for Buildings (NECB), and passive house (PH) under two climate zones in British Columbia, Canada. SRES A2, RCP-4.5 and RCP-8.5 emission scenarios are used to generate future horizon weather data for 2020, 2050, and 2080. The simulation results show that for both bylaw and PH cases, the heating energy consumption would be reduced while cooling energy consumption would be increased. As a result, for the bylaw case, the total energy consumption would be decreased for two climate zones, while for PH case, the total energy consumption would be increased for zone 4 and decreased for zone 7. In addition, the number of h...
Energy Procedia, 2015
Wind-driven rain (WDR) is one of the most important causes for water damage in buildings. Therefo... more Wind-driven rain (WDR) is one of the most important causes for water damage in buildings. Therefore, the first crucial step to assess the hygrothermal performance of the building envelope, is the appropriate estimation of the amount of rainwater striking the building's façade. ISO 15927 offers the annual average index-mainly to assess the moisture content of absorbent surfaces, and the spell index-more related to the likelihood of water penetration through joints. To calculate these indices, assumptions are made concerning the length of the period of 'no rain', called 'spell definition'. Obviously, the choice of this spell definition will characterise the WDR-amount. In this paper, WDR measurements of a 3-storey building in Vancouver, Canada are used to investigate how this spell definition affects the rain load. Different filter criteria are used to exclude errors due to measurement equipment. By means of the catch ratio as a dimensionless parameter, the results of the analysis for different spell definitions are compared to hourly and 5-min data. It is concluded that longer spell definitions result in lower catch ratios and an underestimation of the WDR load. Hourly data turns out to be a more conservative approach for WDR-assessment of this case study, but is able to represent the spread on the catch ratio most closely to the original 5min-dataset.
Wind-driven rain is known to be a major source of moisture loads on building envelopes and is res... more Wind-driven rain is known to be a major source of moisture loads on building envelopes and is responsible for numerous cases of building envelope failures. One of the classic solutions for preventing the building envelope from being extensively exposed to wind-driven rain is the use of overhangs. Previous studies have shown that the introduction of the overhang can change both the amount and the pattern of the wind-driven rain wetting of the facade significantly. In this work, the effects of overhangs on the distribution of wind-driven rain on the windward facade of a low-rise building are discussed based on the results of numerical simulations. It is shown that roof overhangs significantly reduce the amount of wind-driven rain deposition on the upper half of the facade.Wind speed is found to have a large influence on the protection that the overhang provides, while the intensity of rainfall does not have a significant effect. A physical explanation of the effects of overhangs is al...
Climate data is one of the most important inputs for hygrothermal simulations and significantly i... more Climate data is one of the most important inputs for hygrothermal simulations and significantly influences the simulation results that are used for moisture performance assessment of building envelopes. Conventionally, climate data from representative weather stations are used for hygrothermal simulations to assess the moisture performance of the buildings. Recently, the Construction Research Centre of the National Research Council Canada generated historical and future climate data for 564 locations across Canada. In this paper, the climate data of four urban locations within Vancouver (a humid and warm coastal city in Canada) were selected for hygrothermal simulations. These include an open area at the airport, a city center, an area surrounded by plants, and an area surrounded by a water body. The 31-year-long simulations were performed for a typical woodframe wall assembly complying with moisture protection designs as provided in the National Building Code Canada (NBCC 2020) but rain penetration was assumed considering the deficiency of exterior cladding. The differences in its hygrothermal response across the four locations were analyzed. It was found that some climate parameters are significantly different among the selected locations, although the values for moisture indices given in the NBCC 2020 for these locations are all similar. The results show that high values of WDR are the dominant factor that drives the moisture performance but there is no indication that the design of the assembly could be different among the tested locations.
E3S web of conferences, 2021
Canadian Journal of Civil Engineering, Nov 1, 2019
In terms of hygrothermal performance, solid wood panels such as cross-laminated timber (CLT) are ... more In terms of hygrothermal performance, solid wood panels such as cross-laminated timber (CLT) are sensitive to moisture. However, the previous studies on the hygrothermal performance of CLT external envelopes have not indicated the critical moisture conditions for CLT external walls. Therefore, our main objective was to set limit values as hygrothermal criteria for the design of CLT external walls in terms of moisture conditions using a stochastic approach to ensure safe hygrothermal performance. Hygrothermal performance was evaluated by simplified 1D validated calculation models based on the field measurements [1]. Peer-review under the responsibility of the organizing committee of the ICMB23.
Building Simulation, Mar 1, 2021
Building and Environment, Dec 1, 2018
As energy consumption has become an important issue in building design, most building codes requi... more As energy consumption has become an important issue in building design, most building codes require a higher insulation level for building envelopes to improve the building's energy efficiency. However, the highly insulated walls may lead to a higher risk of moisture problems. Although hygrothermal simulation has been widely used to investigate the moisture performance of wood framed walls, the uncertainties of input parameters such as material properties, boundary conditions and moisture loads, may lead to discrepancies between simulation results and actual performance of the envelope. This paper investigates the hygrothermal performance of highly insulated wood framed walls using a stochastic approach, which combines the Latin Hypercube Sampling method and Factorial Design to take into account the uncertainties of material properties, boundary conditions and moisture loads (air leakage and rain leakage). The investigated walls include an I-joist deep cavity wall, two exterior insulated walls, and a conventional 2x6 stud wall as the baseline. It is found that under the moisture loads introduced (i.e. air leakage and rain leakage), the exterior insulated walls have a lower mold growth risk than the deep cavity wall and the 2x6 stud baseline wall. The uncertainties of material properties do not result in significant variations in simulation results such as moisture content and mold growth index as uncertainties of moisture loads do. The hygrothermal performance of these highly insulated walls is more sensitive to moisture loads and the significance of the moisture loads (air leakage and rain leakage) depends on climatic conditions.
Buildings
In response to Canada’s commitment to reducing greenhouse gas emissions and to making pathways to... more In response to Canada’s commitment to reducing greenhouse gas emissions and to making pathways to achieve carbon neutral buildings, this paper presents two real case studies. The paper first outlines the potential of trees to absorb CO2 emissions through photosynthesis, and the methods used for the estimation of their annual carbon sequestration rates. The net annual carbon sequestration rate of 0.575 kgCO2eq/m2 of tree cover area is considered in our study. Then, this paper presents the carbon life cycle assessment of an all-electric laboratory at Concordia University and of a single-detached house, both located in Montreal. The life cycle assessment (LCA) calculations were performed using two software tools, One Click LCA and Athena Impact Estimator for Buildings. The results in terms of Global Warming Potential (GWP) over 60 years for the laboratory were found to be 83,521 kgCO2eq using One Click LCA, and 82,666 kgCO2eq using Athena. For the single-detached house that uses natura...
Healthy, Intelligent and Resilient Buildings and Urban Environments, 2018
Extreme cold climates and Canada's sparsely populated Northern regions have limited human and inf... more Extreme cold climates and Canada's sparsely populated Northern regions have limited human and infrastructural capacity making it difficult to build energy-efficient homes. Despite such differences, homes are built based on codes and standards developed for Canada's South. In 2008, a by-law was passed in Yellowknife, Canada requiring a minimum EnerGuide Housing (EGH) rating of 80 for all new single-family and two-family residential buildings. The EnerGuide's Energy Rating Service (ERS) program is an energy assessment program for residential housing formerly known as the EnerGuide Rating for Houses (EGH). Homes are rated between 0 to 100; lower numbers represent homes that are less efficient and 100 represents an airtight and well-insulated house that is net-zero energy. 1002 homes from the City of Yellowknife evaluated since 1950s were studied from the ERS database, Performance metrics studied include energy intensity, EGH rating, ACH rating, window types, the thermal resistance of the building envelope, primary heating and hot water heating equipment's efficiencies, total electricity used, and total energy used. The analysis identified the current state of housing in Yellowknife, past and present housing trends, and determined the effect of the city of Yellowknife's new building by-law had on housing performance. The preliminary finding shows a pathway to significantly improve the energy efficiency of the housing stock in Yellowknife. This regulation shows other municipalities in Canada that legislations pushing energy efficient buildings can be very effective.
Energy and Buildings, 2015
The existence of thermal bridges in building envelopes affects the energy performance of building... more The existence of thermal bridges in building envelopes affects the energy performance of buildings, their durability and occupants' thermal comfort. Typically the effect of thermal bridges on the energy performance is taken into account by implementing an equivalent U-value in 1D whole building energy simulation program. This treatment accounts for the effect of thermal bridges on the overall thermal transmittance, while their thermal inertia effect is ignored. The presence of thermal bridges not only reduces the overall thermal resistance but also changes the dynamic thermal characteristics of the envelope. This paper investigates the dynamic effect of thermal bridges on the energy performance of residential buildings through simulations. A two-story residential building is used as a case study. Three methods, namely equivalent U-value method, equivalent wall method, and direct 2D/3D modeling method, are implemented in WUFI Plus, a whole building Heat, Air and Moisture (HAM) modeling program. Simulations are carried out for two climates with different insulation levels. Simulation results show that for the cold climate the annual heating load of this building with the inclusion of thermal bridges modeled using 3D dynamic method is 8-13% higher than that modeled using the equivalent U-value method, and 4-9% higher than that modeled using the equivalent wall method. With the increase of the insulation level, the percentage effect of thermal bridges on the heating load increases, while the difference among the three methods decreases. For the hot climate, simulation results show that the presence of thermal bridges increases the annual cooling load by 20%. Compared to the 3D dynamic method, the annual cooling load is underestimated by 17% using the equivalent U-value method and by 14% using the equivalent wall method, respectively.
Buildings
The building sector is responsible for nearly 40% of the total global direct and indirect CO2 emi... more The building sector is responsible for nearly 40% of the total global direct and indirect CO2 emissions. Urban green infrastructure, which includes features such as urban trees, vegetation, green roofs, and green facades, are examples of nature-based solutions often employed as municipal climate mitigation and adaptation strategies. This approach offers a range of cost-effective strategies for reducing municipal CO2 emissions and presents compelling public policy co-benefits such as improved urban livability and enhanced environmental conditions. For municipalities to confidently deploy these solutions at a scale necessary to achieve climate benefits, acquiring knowledge of quantifiable and demonstrated outcomes is an essential requirement. The objectives of this paper are to (1) provide a comprehensive analysis of the advantages and limitations of nature-based solutions (NBS) to address the challenge of reducing CO2 emissions; (2) evaluate existing design guidelines and policies as...
Drying and wetting can occur locally at different parts of a building envelope and involve simult... more Drying and wetting can occur locally at different parts of a building envelope and involve simultaneous heat, air, and moisture transfer. These dynamic wetting and drying processes can be captured using advanced hygrothermal models. In this paper, the one-dimensional hygrothermal model HAMFit is used to simulate the dynamic hygrothermal responses of a sheathing board in a prefabricated wall system. The walls comprise the following layers: fiber-cement board as a cladding layer, plywood as a sheathing board, expanded polystyrene (EPS) as insulation, gypsum board as an interior layer, and 6 mil polyethylene sheet as a vapor and air barrier. The simulation results were compared with measured data from an experiment carried out at the field Building Envelope Test Facility, Building Science Centre of Excellence (BSCE), British Columbia Institute of Technology (BCIT). The model’s prediction, using the measured indoor and outdoor boundary conditions, of the transient temperature and moistu...
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2021
As the urban population grows and the global economy develops, municipal solid waste management (... more As the urban population grows and the global economy develops, municipal solid waste management (MSWM) has become an increasingly prominent global issue. MSWM is particularly difficult in developing countries due to its high cost and time-consuming nature. The Environment-based design (EBD) can potentially contribute to global MSWM by reducing costs and increasing efficiency, especially in helping developing countries identify critical issues in MSWM. This paper uses and demonstrates the effectiveness and efficiency of the EBD method to analyze and identify critical issues in MSWM, using the city of Nairobi as a case study. This paper contains the first two of EBD's three activities: environment analysis and conflict identification, during the design problem period, design knowledge, and design solutions simultaneously and interdependently evolve as a part of the environment. The comparison with the existing literature confirms that the conclusions reached are, to some extent, reliable, time-saving, and less costly, which will offer a possibility to solve the problem of MSWM in impoverished areas.
E3S Web of Conferences, 2020
With the anticipated increase in temperature and solar radiation and frequency of extreme weather... more With the anticipated increase in temperature and solar radiation and frequency of extreme weather conditions due to climate change, buildings typically designed/built in Canadian cold climates would experience increased risks of summer overheating. This paper focuses on how these existing buildings perform under a current extreme year and projected future climates. Results show that the thermal conditions of a single-family detached house built in 1964 and 1990 are more comfortable than the house built to meet the current National Energy Code of Canada for Buildings (NECB) and high energy-efficient building (HEEB) without including natural ventilation by up to 50%. On the other hand, when natural ventilation is included, the house built to NECB and HEED are more comfortable. Sensitivity analysis is carried out to evaluate the influence of five design parameters, i.e. wall and roof insulation, airtightness, U-value and SHGC of windows. Sensitivity analysis shows that wall insulation,...
MATEC Web of Conferences, 2019
Buildings now produce more than a third of global greenhouse gases, making them more than any oth... more Buildings now produce more than a third of global greenhouse gases, making them more than any other sector contributing to climate change. This paper investigates the effect of climate change on the energy performance and thermal comfort of a high-rise residential building with different energy characteristic levels, i.e. bylaw to meet current National Energy Code of Canada for Buildings (NECB), and passive house (PH) under two climate zones in British Columbia, Canada. SRES A2, RCP-4.5 and RCP-8.5 emission scenarios are used to generate future horizon weather data for 2020, 2050, and 2080. The simulation results show that for both bylaw and PH cases, the heating energy consumption would be reduced while cooling energy consumption would be increased. As a result, for the bylaw case, the total energy consumption would be decreased for two climate zones, while for PH case, the total energy consumption would be increased for zone 4 and decreased for zone 7. In addition, the number of h...
Energy Procedia, 2015
Wind-driven rain (WDR) is one of the most important causes for water damage in buildings. Therefo... more Wind-driven rain (WDR) is one of the most important causes for water damage in buildings. Therefore, the first crucial step to assess the hygrothermal performance of the building envelope, is the appropriate estimation of the amount of rainwater striking the building's façade. ISO 15927 offers the annual average index-mainly to assess the moisture content of absorbent surfaces, and the spell index-more related to the likelihood of water penetration through joints. To calculate these indices, assumptions are made concerning the length of the period of 'no rain', called 'spell definition'. Obviously, the choice of this spell definition will characterise the WDR-amount. In this paper, WDR measurements of a 3-storey building in Vancouver, Canada are used to investigate how this spell definition affects the rain load. Different filter criteria are used to exclude errors due to measurement equipment. By means of the catch ratio as a dimensionless parameter, the results of the analysis for different spell definitions are compared to hourly and 5-min data. It is concluded that longer spell definitions result in lower catch ratios and an underestimation of the WDR load. Hourly data turns out to be a more conservative approach for WDR-assessment of this case study, but is able to represent the spread on the catch ratio most closely to the original 5min-dataset.
Wind-driven rain is known to be a major source of moisture loads on building envelopes and is res... more Wind-driven rain is known to be a major source of moisture loads on building envelopes and is responsible for numerous cases of building envelope failures. One of the classic solutions for preventing the building envelope from being extensively exposed to wind-driven rain is the use of overhangs. Previous studies have shown that the introduction of the overhang can change both the amount and the pattern of the wind-driven rain wetting of the facade significantly. In this work, the effects of overhangs on the distribution of wind-driven rain on the windward facade of a low-rise building are discussed based on the results of numerical simulations. It is shown that roof overhangs significantly reduce the amount of wind-driven rain deposition on the upper half of the facade.Wind speed is found to have a large influence on the protection that the overhang provides, while the intensity of rainfall does not have a significant effect. A physical explanation of the effects of overhangs is al...