An explorative study on the potential of green roofs providing thermal comfort conditions for indoor spaces in Kumasi, Ghana

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Christian Koranteng ◽  
David Nyame-Tawiah ◽  
Kwabena Abrokwa Gyimah ◽  
Barbara Simons
Keyword(s):  
Climate Change ◽  
Thermal Comfort ◽  
Leaf Area ◽  
Energy Use ◽  
Green Roofs ◽  
Weather Data ◽  
Indoor Temperature ◽  
Content Type ◽  
Mean Temperature ◽  
Test Cells

PurposeAs the global population keeps increasing with its associated urbanisation and climate change issues being experienced in various degrees worldwide, there is the need to find mitigating measures to improve thermal conditions within spaces. The study aimed to evaluate green roofs to determine whether they could provide thermal comfort within residential buildings.Design/methodology/approachForty-two-year weather data were retrieved from the Kumasi weather station to establish the pattern of the climatic variables. Furthermore, an experiment was conducted by constructing test cells to determine the potential of vegetation/green roofs on temperature development within spaces. This approach led to a simulation-based exploration of the thermal performance of the test cells to probe variables that could lead to the reduction in temperature after the models in the software (design-builder) had been validated.FindingsThe results on the 42 years (1976–2018) weather data showed a significant (p = 0.05) mean temperature increment of 2.0 °C. The constructed test cell with Setcreasea purpurea (Purple Heart) vegetation showed an annual mean temperature reduction of 0.4 °C (p = 0.05). In addition, the exploration using the simulation application showed combinations of various soil depth (70–500 mm) and leaf area indices (leaf area index of 2–5) having a potential to lower indoor temperature by 1.5 °C and its associated reduction in energy use. The option of green roofs as a valuable alternative to conventional roofs, given their potential in mitigating climate change, must be encouraged. A survey of occupants in six selected neighbourhoods in Kumasi showed varying subjective perceptions of several green issues (24–98%) and increases in temperature values because of the loss of greenery in the city.Originality/valueEmpirical data that point to the significant reduction of indoor temperature values and a subsequent reduction in energy use have been unearthed. Therefore, built environment professionals together with city authorities could invest in these sustainable measures to help humanity.

scholarly journals Determination of the Effect of Green Roofs on Indoor Temperature by the Use of Simulation in a Tropical Landscape

2020 ◽  
pp. 12-28
Author(s):  
D. Nyame-Tawiah ◽  
L. Attuah ◽  
C. Koranteng
Keyword(s):  
Thermal Comfort ◽  
Leaf Area ◽  
Study Design ◽  
Soil Depth ◽  
Real Life ◽  
Green Roofs ◽  
Simulation Design ◽  
Indoor Temperature ◽  
Soil Thickness ◽  
Construction Methods

Aims: To use a simulation base exploration to carry out 6 scenarios of green roof construction methods to determine the most efficient in improving indoor thermal comfort. Study Design: Simulation Design was used as the study design. Place and Duration of Study: The study was conducted at the Department of Horticulture – Kwame Nkrumah University of Science and Technology located at Kumasi-Ghana between 2016 and 2019. Methodology: A simulation experimental setup was done to run for 1 year to cover the two seasons in Ghana. Version 5.0.2 Design Builder and Energy Plus 5.8 was used to work on 6 scenarios using leaf area indexes (LAI) of 2 and 5 as well as soil depth (thickness) of (70-150 mm), 200 mm, 300 mm and 500 mm. Also a real life experiment was done at the Department of Horticulture by constructing 9 test cells and using treatments such as Portulaca grandiflora and Setcreasea purpurea to validate the results for the simulation. The time setup for the simulation was from 12.00 am to 11.59 pm. Results: A leaf area indexes (LAI) of 5 and soil depth of 70 mm-150 mm recorded the lowest simulated temperature ranging from 26.26°C to 29.30°C for scenario one. For scenario two, a leaf area indexes (LAI) of 5 and a soil depth of 200mm recorded the lowest significantly (P≤0.05) indoor temperature in August (26.20°C) and the highest (29.26°C) in March. In February, June and August, significant differences (P≤0.05) were achieved by leaf area indexes (LAI) 5 and soil thickness 500 mm for scenario three. January, March to July indicated significant differences (P≤0.05) between the treatments leaf area indexes (LAI) 2 and soil thickness 300 mm and leaf area indexes (LAI) 5 and soil depth of 300 mm recorded 26.32°C to 29.33°C for August and March respectively for scenario four. A soil depth of 500 mm and leaf area indexes (LAI) of 2 gave significantly (P≤0.05) low temperatures indoors all year (26.27 to 29.32°C) for scenario five and in August leaf area indexes (LAI) 5 and soil thickness of 500 mm recorded the least temperature all year for scenario six. Conclusion: From the exploration, a soil depth of 70 mm – 150 mm and a LAI of 5, LAI of 5 and soil depth of 200 mm and LAI of 2 and soil depth of 500 mm achieved the lowest temperature and performed better in terms of temperature reduction which will lead to thermal comfort of occupants.

scholarly journals The study of potential evapotranspiration in future periods due to climate change in west of Iran

2018 ◽  
Vol 10 (1) ◽  
pp. 161-177 ◽  
Author(s):  
Ahmad Rajabi ◽  
Zahra Babakhani
Keyword(s):  
Climate Change ◽  
Potential Evapotranspiration ◽  
Circulation Model ◽  
Weather Data ◽  
Maximum Temperature ◽  
Global Circulation Model ◽  
Content Type ◽  
Global Circulation ◽  
Change Effect ◽  
Climate Change Effect

Purpose This study aims to present the climate change effect on potential evapotranspiration (ETP) in future periods. Design/methodology/approach Daily minimum and maximum temperature, solar radiation and precipitation weather parameters have been downscaled by global circulation model (GCM) and Lars-WG outputs. Weather data have been estimated according to the Had-CM3 GCM and by A1B, A2 and B1 scenarios in three periods: 2011-2030, 2045-2046 and 2080-2099. To select the more suitable method for ETP estimation, the Hargreaves-Samani (H-S) method and the Priestly–Taylor (P-T) method have been compared with the Penman-Monteith (P-M) method. Regarding the fact that the H-S method has been in better accordance with the P-M method, ETP in future periods has been estimated by this method for different scenarios. Findings In all five stations, in all three scenarios and in all three periods, ETP will increase. The highest ETP increase will occur in the A1B scenario and then in the A1 scenario. The lowest increase will occur in the B1 scenario. In the 2020 decade, the highest ETP increase in three scenarios will occur in Khorramabad and then Hamedan. Kermanshah, Sanandaj and Ilam stations come at third to fifth place, respectively, with a close increase in amount. In the 2050 decade, ETP increase percentages in all scenarios are close to each other in all the five stations. In the 2080 decade, ETP increase percentages in all scenarios will be close to each other in four stations, namely, Kermanshah, Sanandaj, Khorramabad and Hamedan, and Ilam station will have a higher increase compared with the other four stations. Originality/value Meanwhile, the highest ETP increase will occur in hot months of the year, which are significant with regard to irrigation and water resources.

scholarly journals Technical considerations in green roof retrofit for stormwater attenuation in the Central Business District

2015 ◽  
Vol 33 (1) ◽  
pp. 36-51 ◽  
Author(s):  
Sara Wilkinson ◽  
Jessica Lamond ◽  
David G Proverbs ◽  
Lucy Sharman ◽  
Allison Heller ◽  
...  
Keyword(s):  
Built Environment ◽  
Focus Groups ◽  
Energy Use ◽  
Relevant Literature ◽  
Green Roof ◽  
Green Roofs ◽  
Environmental Benefits ◽  
Design Stage ◽  
Due Diligence ◽  
Content Type

Purpose – The key aspects that built environment professionals need to consider when evaluating roofs for the purpose of green roof retrofit and also when assessing green roofs for technical due diligence purposes are outlined. Although green or sod roofs have been built over many centuries, contemporary roofs adopt new approaches and technologies. The paper aims to discuss these issues. Design/methodology/approach – A mixed methods design based on a systematic review of relevant literature from parallel disciplines was used to identify and quantify the social, economic and environmental benefits of retrofitted green roofs in commercial districts. The technical issues of concern were drawn from a desk-top survey of literature and from stakeholder focus groups undertaken in Sydney in 2012. Findings – There are perceptions amongst built environmental practitioners that may act as artificial barriers to uptake. There is little direct experience within built environment professionals and practitioners, along with a fear of the unknown and a risk averse attitude towards perceived innovation which predicates against green roof retrofit. Furthermore projects with green roofs at inception and early design stage are often “value engineered” out of the design as time progresses. There is a need for best practice guidance notes for practitioners to follow when appraising roofs for retrofit and also for technical due diligence purposes. Research limitations/implications – The focus groups are limited to Sydney-based practitioners. Although many of these practitioners have international experience, few had experience of green roofs. A limited number of roof typologies were considered in this research and some regions and countries may adopt different construction practices. Practical implications – In central business districts the installation of green roof technology is seen as one of the main contributors to water sensitive urban design (WSUD). It is likely that more green roofs will be constructed over time and practitioners need knowledge of the technology as well as the ability to provide best advice to clients. Originality/value – The benefits of green roofs as part of WSUD are increasingly being recognised in terms of reduced flood risk, reduced cost of drainage, improved water quality and lower energy use, as well as other less tangible aspects such as aesthetics and amenity. This research highlights the lack of understanding of the short- and long-term benefits, a poor appreciation and awareness of these benefits; a lack of technical knowledge and issues to be considered with regard to green roofs on behalf of practitioners. The study has highlighted the need for specific training and up-skilling in these areas to provide surveyors with the technical expertise needed. There is also a need to consider how the emerging retrofit and adaptation themes are best designed into the curriculum at both undergraduate and postgraduate levels. Clearly, if the potential benefits of green roofs are to be realised in the future, building professionals need to be fully conversant with the technology and be able to provide reliable and accurate advice.

scholarly journals Propuesta de materiales termoaislantes para desarrollo de casa-habitación adecuada a cambios climáticos con eficiencia energética

2019 ◽  
pp. 1-5
Author(s):  
Francisco Gibranny Curiel-Sanchez ◽  
Ixchel Astrid Camacho-Ixta
Keyword(s):  
Climate Change ◽  
Environmental Impact ◽  
Thermal Comfort ◽  
Energy Use ◽  
Basic Needs ◽  
Building Envelope ◽  
Human Being ◽  
Insulating Materials ◽  
Thermal Insulating ◽  
Sustainable Materials

The condition of climate change is attributed directly or indirectly to activities related to the human being, as a more transcendental effect the increase of temperature is highlighted. Such a condition is not taken into account in the development of current constructions, so it is sought to propose the use of thermal insulating materials that will give a thermal comfort to the user and a reduction of energy use, which in turn will be an environmental advantage. There are various types of thermal insulating materials, however, it is proposed to be sustainable, as it is intended not to contribute to climate change and to meet the appropriate specifications of the building envelope, in order to ensure the users comfort of current and future dwellings, different factors, such as orientation, as well as specific parameters, will be taken into account as part of the development of the aforementioned ones. The construction development of the current house-room does not take into account the continuous thermal alterations that occur by the continuous climate change, ignoring the basic needs of the thermal comfort of the user; so sustainable materials are recommended, which meet thermoinsulating properties without causing an environmental impact.

scholarly journals Could refurbishment of “traditional” buildings reduce carbon emissions?

2014 ◽  
Vol 4 (3) ◽  
pp. 221-237 ◽  
Author(s):  
Richard Atkins ◽  
Rohinton Emmanuel
Keyword(s):  
Climate Change ◽  
Energy Use ◽  
Research Study ◽  
Single Case ◽  
Improve Performance ◽  
Content Type ◽  
Post Occupancy Evaluation ◽  
Practical Implications ◽  
Very High

Purpose – Evaluate the post occupancy performance of a typical “traditional” building using multiple post occupancy evaluation (PoE) protocols against design intents to learn lessons about their suitability in meeting UK's climate change reduction targets. The paper aims to discuss these issues. Design/methodology/approach – PoE studies of a single case study, Norton Park, using three PoE methodologies. Gaps and overlaps between the PoE protocols are assessed and their role in improving energy and carbon emission performance of traditional buildings is explored. Findings – Refurbishment of the type undertaken in this case study could halve the energy use in traditional buildings with comparable savings in CO2 emission. Research limitations/implications – Traditional buildings could positively contribute to achieving climate change reduction targets; regular feedback loops improve performance over time. Practical implications – Quantification of the likely national benefit of focusing retrofit actions on traditional buildings is explored. Originality/value – The research study demonstrates that very high levels of energy saving can be achieved when traditional buildings are refurbished. In addition on-going monitoring and PoE studies highlight opportunities to optimise the performance of traditional buildings.

scholarly journals Impact of Passive Cooling on Thermal Comfort in a Single-Family Building for Current and Future Climate Conditions

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5332
Author(s):  
Krzysztof Grygierek ◽  
Izabela Sarna
Keyword(s):  
Thermal Comfort ◽  
Natural Ventilation ◽  
Energy Use ◽  
Weather Data ◽  
Passive Cooling ◽  
Climate Data ◽  
Single Family ◽  
Climate Conditions ◽  
Building Simulations ◽  
Family Building

Today, there is a great deal of emphasis on reducing energy use in buildings for both economic and environmental reasons. Investors strongly encourage the insulating of buildings. Buildings without cooling systems can lead to a deterioration in thermal comfort, even in transitional climate areas. In this article, the effectiveness of natural ventilation in a passive cooling building is analyzed. Two options are considered: cooling with external air supplied to the building by fans, or by opening windows (automatically or by residents). In both cases, fuzzy controllers for the cooling time and supply airflow control are proposed and optimized. The analysis refers to a typical Polish single-family building. Simulations are made with the use of the EnergyPlus program, and the model is validated based on indoor temperature measurement. The calculations were carried out for different climate data: standard and future (warmed) weather data. Research has shown that cooling with external air can effectively improve thermal comfort with a slight increase in heating demand. However, to be able to reach the potential of such a solution, fans should be used.

scholarly journals Energy Use and Perceived Indoor Environment in a Swedish Multifamily Building before and after Major Renovation

2018 ◽  
Vol 10 (3) ◽  
pp. 766 ◽  
Author(s):  
Lina La Fleur ◽  
Patrik Rohdin ◽  
Bahram Moshfegh
Keyword(s):  
Energy Efficiency ◽  
Thermal Comfort ◽  
Indoor Environment ◽  
Energy Use ◽  
Ventilation System ◽  
Heating Season ◽  
Indoor Temperature ◽  
Exhaust Ventilation ◽  
Heat Demand ◽  
Before And After

Improved energy efficiency in the building sector is a central goal in the European Union and renovation of buildings can significantly improve both energy efficiency and indoor environment. This paper studies the perception of indoor environment, modelled indoor climate and heat demand in a building before and after major renovation. The building was constructed in 1961 and renovated in 2014. Insulation of the façade and attic and new windows reduced average U-value from 0.54 to 0.29 W/m2·K. A supply and exhaust ventilation system with heat recovery replaced the old exhaust ventilation. Heat demand was reduced by 44% and maximum supplied heating power was reduced by 38.5%. An on-site questionnaire indicates that perceived thermal comfort improved after the renovation, and the predicted percentage dissatisfied is reduced from 23% to 14% during the heating season. Overall experience with indoor environment is improved. A sensitivity analysis indicates that there is a compromise between thermal comfort and energy use in relation to window solar heat gain, internal heat generation and indoor temperature set point. Higher heat gains, although reducing energy use, can cause problems with high indoor temperatures, and higher indoor temperature might increase thermal comfort during heating season but significantly increases energy use.

scholarly journals Modelling the Impacts of Climate Change on Building Heating and Cooling Energy Use in Toronto

2021 ◽  
Author(s):  
Pouriya Jafarpur
Keyword(s):  
Climate Change ◽  
Energy Demand ◽  
Energy Use ◽  
Dynamical Downscaling ◽  
Ghg Emissions ◽  
Building Energy ◽  
Weather Data ◽  
Existing Building ◽  
Average Decrease ◽  
The Future

The study describes the results of climate change impact assessment on building energy use in Toronto, Canada. Accordingly, three future weather data sets are generated and applied to the energy simulation of 16 building prototypes. Both statistical and dynamical downscaling techniques are used to generate the future weather files. The results indicate an average decrease for the future in the range of 18-33% in heating EUI, and an average increase of 16-126% in cooling EUI, depending on the baseline climate and building type. In addition, the GHG emissions for each building model are presented. It is concluded that the application of future weather files for building performance simulation leads to a better quantification of building energy demand in the future than a historical weather file. Furthermore, the results demonstrate the need to modify and adapt existing building modelling regulations and to plan future building according to the future climate.

scholarly journals Green Roofs and Greenpass

Buildings ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 205 ◽  
Author(s):  
Scharf ◽  
Kraus
Keyword(s):  
Climate Change ◽  
Thermal Comfort ◽  
Green Infrastructure ◽  
Climate Adaptation ◽  
Urban Climate ◽  
Green Roofs ◽  
Well Being ◽  
Status Quo ◽  
Assessment System ◽  
Urban Energy Balance

The United Nations have identified climate change as the greatest threat to human life. As current research shows, urban areas are more vulnerable to climate change than rural areas. Numerous people are affected by climate change in their daily life, health and well-being. The need to react is undisputed and has led to numerous guidelines and directives for urban climate adaptation. Plants are commonly mentioned and recommended as one key to urban climate adaptation. Due to shading of open space and building surfaces, as well as evapotranspiration, plants reduce the energy load on the urban fabric and increase thermal comfort and climate resilience amongst many other ecosystem services. Plants, therefore, are described as green infrastructure (GI), because of the beneficial effects they provide. Extensive green roofs are often discussed regarding their impact on thermal comfort for pedestrians and physical properties of buildings. By means of Stadslab2050 project Elief Playhouse in Antwerp, Belgium, a single-story building in the courtyard of a perimeter block, the effects of different extensive green roof designs (A and B) on the microclimate, human comfort at ground and roof level, as well as building physics are analyzed and compared to the actual roofing (bitumen membrane) as the Status Quo variant. For the analyses and evaluation of the different designs the innovative Green Performance Assessment System (GREENPASS®) method has been chosen. The planning tool combines spatial and volumetric analyses with complex 3D microclimate simulations to calculate key performance indicators such as thermal comfort score, thermal storage score, thermal load score, run-off and carbon sequestration. Complementary maps and graphs are compiled. Overall, the chosen method allows to understand, compare and optimize project designs and performance. The results for the Elief Playhouse show that the implementation of green roofs serves a slight contribution to the urban energy balance but a huge impact on the building and humans. Variant B with entire greening performs better in all considered indicators, than the less greened design Variant A and the actual Status Quo. Variant B will probably bring a greater cost/benefit than Variant A and is thus recommended.

scholarly journals Assessing the Performance Gap of Climate Change on Buildings Design Analytical Stages Using Future Weather Projections

2020 ◽  
Vol 24 (3) ◽  
pp. 119-134
Author(s):  
Ibrahim Alhindawi ◽  
Carlos Jimenez-Bescos
Keyword(s):  
Climate Change ◽  
Thermal Comfort ◽  
Ghg Emissions ◽  
Weather Data ◽  
Dynamic Simulations ◽  
Performance Gap ◽  
Remarkable Effect ◽  
Thermal Status ◽  
High Emission ◽  
Climate Analysis

AbstractWith the higher pace of climate change, temperatures are rising each year, resulting in various effects on the thermal status of buildings. This paper takes the opportunity of analysing different scenarios of greenhouse gas (GHG) emissions using hourly weather data of future projections by implementing EPW weather files on EnergyPlus software dynamic simulations, coupled with architectural science methods of climate analysis, to test the effect of high and medium-high emission scenarios for the 2050s and 2080s future timelines on thermal comfort range, passive zones potential, and heating/cooling periods, as compared to the weather data from 2003–2017. Simulations results have shown a remarkable effect on the scale of daily cooling hours and monthly coverage under the high GHG emission scenario, expanding its range by 60 %, with 6 hours on summer peak days and 3 months/year, as well as an annual decrease in heating period by 33.3 %. Thermal comfort zones of tested periods have also witnessed an alternation, translating the effect on the passive cooling and passive heating zones’ way of variating, where the ranges are pushed towards their potential limits. Results have also demonstrated that if future weather data is not included in simulations, a weather-related performance gap is generated.

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