Browsing by Author "Ge, Hua"

Now showing 1 - 9 of 9
  • No Thumbnail Available
    Item
    Assessing and mitigating overheating risk in existing Canadian school buildings under extreme current and future climates
    (Elsevier, 2022) Mutasim Baba, Fuad; Ge, Hua; (Leon) Wang, Liangzhu; Zmeureanu, Radu
    Canadian buildings have been primarily designed to withstand cold and long winters, not hot summers. With climate change and the increase in the intensity and severity of heatwaves, it has become important to investigate overheating in buildings. However, there are limited studies on assessing and mitigating the overheating risk in existing buildings that house vulnerable populations in cold climates, especially in Canada. This paper provides a framework for the systematic assessment of overheating risks and the development of passive mitigation strategies to reduce the overheating risks without increasing cool ing energy consumption under current and future climates with simulation models that are calibrated based on measured indoor air temperatures and outdoor weather conditions. The framework is applied to a school building built in 1958. The calibrated building model achieved an RMSE of less than 0.6 C compared with measurements, a Maximum-Absolute-Difference of less than 1.9 C, and a 1 C Percentage-Error of less than 10 %. The simulation results from the calibrated model predicted 110 over heating hours during the year 2020. The use of exterior blind roll or a combination of night cooling and other mitigation measures that reduce solar heat gain can achieve acceptable thermal conditions. In 2044 (the future extreme midterm year), night cooling with the exterior blind roll shading would be required during extreme heat events. Whereas during 2090 (the future long-term extreme year), additional mit igation measures such as a cool roof may be required to achieve an acceptable level of thermal conditions in the school.
  • No Thumbnail Available
    Item
    Calibration of building model based on indoor temperature for overheating assessment using genetic algorithm: Methodology, evaluation criteria, and case study
    (Building and Environment 207 (2022) 108518, 2022) Mutasim Baba, Fuad; Ge, Hua; Zmeureanu, Radu; (Leon) Wang, Liangzhu
    With the increased severity, intensity, and frequency of “heatwaves” due to climate change, it has become imperative to study the overheating risks in existing buildings. To do so, a building simulation model needs to be calibrated based on measured indoor temperatures under the current weather conditions. This paper presents a robust automated methodology that can calibrate a building simulation model based on the indoor hourly temperature in multiple rooms simultaneously with high accuracy. This methodology includes a variance-based sensitivity analysis to determine building parameters that significantly influence indoor air temperatures, the Multi-Objective Genetic Algorithm to calibrate different rooms simultaneously based on the significant param eters identified by the sensitivity analysis, and new evaluation criteria to achieve a high-accuracy calibrated model. Maximum Absolute Difference (MAD), a new metric, that calculates the maximum absolute difference between simulated and measured hourly indoor temperatures, Root Mean Square Error (RMSE), Normalized Mean Bias Error (NMBE) were used as the evaluation criteria. Another new metric is introduced, 1 ◦C Percentage Error criterion that calculates the percentage of the number of hours with an error over 1 ◦C during the cali bration period, to select the best solutions from the Pareto Front solutions. 0.5 ◦C Percentage Error criterion is also used for the level of accuracy the model can achieve. It was found that the calibrated model achieved these metrics with RMSE of 0.3 ◦C, and MAD of 0.8 ◦C, and 85% of data points with an error less than 0.5 ◦C for a school building case.
  • No Thumbnail Available
    Item
    Do high energy-efficient buildings increase overheating risk in cold climates? Causes and mitigation measures required under recent and future climates
    (Elsevier, 2022) Mutasim Baba, Fuad; Ge, Hua; (Leon) Wang, Liangzhu; Zmeureanu, Radu
    Contradictory findings are reported in the literature showing that high energy-efficient buildings have either higher or lower overheating risks compared to old buildings. A methodology is developed using the Global and Local Sensitivity Analysis to quantify the contribution and correlation of individual building envelope parameter to the change in indoor operative temperature. This methodology is applied to an archetype Canadian detached house as a case study to evaluate its overheating risk. The building envelope thermal characteristics studied represent houses built in different periods from 1950 to high energy-efficient buildings in Montreal under different weather generations: typical historical (1961–1990), recent observational (2016), and typical future years 2030 (2026–2045) and 2090 (2080–2099) generated based on RCP-4.5 and 8.5 scenarios. The results showed that the high energy-efficient buildings can be more resilient to climate change than old buildings if adequate ventilation is provided, where the decrease of window and wall U-value, and SHGC all contribute to the decrease in indoor temperature. While without adequate ventilation, the overheating risk in high-energy-efficient buildings can be higher than old buildings, where decreasing wall and window U-values and infiltration rate has a greater contribution to the increase of indoor temperature, while decreasing window SHGC has a lower contribution to the decrease in indoor temperature compared to the case with adequate ventilation. The results also showed that natural ventilation in the high energy-efficient buildings is sufficient to reduce the overheating risk under the current climate but will require additional interior and exterior shading under future climates.
  • No Thumbnail Available
    Item
    Effect of Climate Change and Extreme Weather Events on the Thermal Conditions of Canadian Multi-unit Residential Buildings
    (ASHRAE, 2019) Mutasim Baba, Fuad; Ge, Hua
    Buildings designed and built in cold climates, such as Canada, are typically optimized for minimizing heating energy demand, however, with climate change, these buildings may experience increased cooling energy demand and overheating risk during the summer. This paper presents the evaluation of the effect of climate change on the thermal conditions of multi-unit residential buildings that meet the current energy code and Passive House (PH) requirements under historical weather year, future horizon years and extreme warm conditions (heat wave) through simulations. A wood-frame mid-rise and a pour-in-place concrete high-rise multi unit residential building are selected as case study buildings.
  • No Thumbnail Available
    Item
    Effect of Climate Change on the Energy Performance and Thermal Conditions of a Single-family Detached House in Canada
    (American Society of Heating, Refrigeration and Air Conditioning Engineers, Inc., 2019) Mutasim Baba, Fuad; Ge, Hua
    The Earth is already suffering some of the effects of climate change, such as rising temperature, more frequent storms, and increased precipitation, etc. Canada seeks to reduce the greenhouse gases emission by a consistent improvement in energy efficiency of buildings from current building code to net-zero energy ready buildings by 2030. These measures will significantly reduce the energy consumption of buildings. However, with the changing climate how these buildings designed based on historical weather data would perform under future climates. This paper attempts to answer this question by investigating the effect of climate change on the energy demand and overheating risk in a single-family detached house with different energy efficiency levels, i.e. NECB that meets current National Energy Code of Canada for Buildings (NECB), and passive house (PH) that meets the PH requirements. Two climate zones in Canada are simulated, i.e. zone 4 (Vancouver); and zone 6 (Montreal). RCP 4.5 and RCP 8.5 emission scenarios are used to generate future climate for 2030, 2060 and 2090 horizon year. The simulation results showed that for both NECB and PH cases and under different climate zones, heating energy demand would be reduced by 5-48% by 2090, while the cooling energy demand as a percentage of the total energy demand would be increased from 0% under historical weather up to 60% by 2090. The climate change affects the PH case more than the NECB case and under zone 6 more than zone 4. The overheating hours would be increased by 27-43% for the NECB case, 44-50% for the PH case, respectively, under predicted 2090 weather conditions without natural ventilation. With the implementation of mitigation strategies such as natural ventilation, the overheating hours under future climate would be reduced to 7% of the summer time for Vancouver and to 21% of the summer time for Montreal. In conclusion, buildings designed based on historical weather data would perform differently under the changing future climates, thus the efforts should be made to design buildings that would be adaptable to climate change.
  • No Thumbnail Available
    Item
    Effect of climate change on the annual energy consumption of a single family house in British Columbia
    (MATEC Web Conf., 2018) Mutasim Baba, Fuad; Ge, Hua
    The Earth is already experiencing some of the effects of climate change, such as rising temperature, more frequent storms, increased precipitation, etc. This paper investigates the effect of climate change on the energy consumption of a single-family house with different energy efficiency levels, i.e. bylaw to meet current National Energy Code of Canada for Buildings (NECB), and passive house (PH) to meet the PH requirements under four climate zones in British Columbia, Canada. SRES A2, RCP 4.5 and RCP 8.5 emission scenarios are used to generate future climate for 2020, 2050, and 2080. The simulation results show that for both bylaw and PH cases, heating energy consumption will be reduced while cooling energy consumption will be increased, as a result for bylaw case, the energy consumption will be decreased for four climate zones, while for PH case, the energy consumption will be increased for zone 4 & 5 and decreased for zone 6 & 7. In climate zone 5, the building fails to meet the PH requirements during 2050. Therefore, buildings designed based on historical weather data will perform differently under the changing future climates, thus the efforts should be made to design buildings that are adaptable to climate change.
  • No Thumbnail Available
    Item
    Feasibility of Planting Trees around Buildings as a Nature-Based Solution of Carbon Sequestration—An LCA Approach Using Two Case Studies
    (MDPI, 2022) Grossi, Felipe; Ge, Hua; Zmeureanu, Radu; Baba, Fuad
    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 seques tration 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 natural gas for space heating and domestic hot water, the GWP was found to be 544,907 kgCO2eq using One Click LCA, and 566,856 kgCO2eq using Athena. For the all-electric laboratory, a garden fully covered with representative urban trees could offset around 17% of the total life cycle carbon emissions. For the natural gas-powered single-detached house, the sequestration by trees is around 3% of the total life cycle carbon emission. This paper presents limits for achieving carbon neutral buildings when only the emissions sequestration by trees is applied, and discusses the main findings regarding LCA calculations under different scenarios.
  • No Thumbnail Available
    Item
    Optimizing overheating, lighting, and heating energy performances in Canadian school for climate change adaptation: Sensitivity analysis and multi-objective optimization methodology
    (Building and Environment, 2023) Mutasim Baba, Fuad; Ge, Hua; Zmeureanu, Radu; (Leon) Wang, Liangzhu
    This paper aims to develop long-term adaptation strategies for the existing Canadian school buildings under extreme current and future climates using a developed methodology based on global and local sensitivity analysis and Multi-Objective Optimization Genetic Algorithm. The calibrated simulation model based on indoor and outdoor measured temperature for a school of interest is used to evaluate the optimization strategies. This paper aims to search for the optimum school building design under three simultaneous conflicting objective functions: (1) the minimization of overheating hours to less than 40 h as required by Building Bulletin BB101 building code by using passive mitigation measures, (2) the minimization of heating energy use to less than 15 kW/m2 ac cording to passive house requirements and thus the reduction of greenhouse gas emissions, and (3) the mini mization of artificial lighting energy use to less than the current lighting energy use by maximization of daylighting usage without exceeding acceptable glare index in classrooms. Ten building design variables are selected, which could generate approximately 300,000 solutions. The developed methodology reduced the numbers to 14,400 solutions and found seven Pareto solutions that comply with the three objectives and their constraints. High energy-efficient building envelope, appropriate window-wall ratio and window type, natural ventilation during the day, and night cooling can play a key role in achieving the objectives under current weather conditions. An additional cool roof and external overhang will be needed in the medium-term future climate, and an additional movable screen shading will be needed in the long-term future climate.
  • No Thumbnail Available
    Item
    Overheating risk of a single-family detached house built at different ages under current and future climate in Canada
    (EDP Sciences, 2020) Mutasim Baba, Fuad; Ge, Hua
    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, airtightness, and windows U-value are the three most significant parameters influencing the overheating risk without natural ventilation. With natural ventilation, the SHGC of windows is the most influencing parameter in reducing overheating risk. This paper confirms that the Canadian buildings have the overheating risk over the hot summer experienced over the past a few years and the risk will be increased in the future. Natural ventilation as a mitigation measure, which has been relied on by building designers in Canada will not be sufficient to remove excess heat or provide thermal comfort to residents. Other mitigation strategies such as shading to reduce the heat gain during the summer, are needed.