scholarly journals Changes in Temperature and Moisture Content of an Extensive-Type Green Roof

2019 ◽  
Vol 11 (9) ◽  
pp. 2498 ◽  
Author(s):  
Anna Baryła ◽  
Tomasz Gnatowski ◽  
Agnieszka Karczmarczyk ◽  
Jan Szatyłowicz
Keyword(s):  
Moisture Content ◽  
Surface Temperature ◽  
Air Temperature ◽  
Green Roof ◽  
Atmospheric Precipitation ◽  
Environmental Parameters ◽  
Green Roofs ◽  
Imaging Camera ◽  
Daily Changes ◽  
Continental Climate

Green roofs ought to be perceived as ensuring a wide-ranging contribution to the sustainable urban environment. The aim of the study was; (1) to investigate and analyse the differences in the surface temperature between four models of green roofs of the extensive type and a conventional roof (covered with bitumen) under the conditions of a continental climate; (2) to assess the influence of environmental parameters (climatic water balance, air temperature, relative humidity, moisture content in the profile) on changes in the temperature of the extensive type green roof profile (substrate and vegetation mat). The study (1) was carried out during the period of June–December 2016 using a thermal imaging camera. As a result, the greatest differences in temperature were noted in June and July, with a maximum difference between the temporary surface temperature of a green roof and a conventional roof of up to 24 °C. The (2) study was conducted on a green roof profile with sedum plant vegetation. The measured parameters were: the temperature of the surface, the temperature and humidity at depths of 3 cm and 15 cm, and active radiation in the photosynthesis process (PAR). As the result, the range of daily changes in the surface temperatures and the vegetation mat were higher than the range of changes in the air temperature. Atmospheric precipitation decreased the thermal gradient in the soil, as well as the temperature fluctuations in the course of a day as a result of the increase in humidity following a rainfall. During the summer period, over the course of a day, the surface temperature was 5 °C higher than the air temperature. The largest correlation was obtained between the air temperature and the temperature of the surface as well as the temperature of the structural layers.

scholarly journals Influence of Temperature and Moisture Content on Thermal Performance of Green Roof Media

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2421
Author(s):  
Bohan Shao ◽  
Caterina Valeo ◽  
Phalguni Mukhopadhyaya ◽  
Jianxun He
Keyword(s):  
Thermal Conductivity ◽  
Moisture Content ◽  
Green Roof ◽  
Green Roofs ◽  
Power Functions ◽  
Thick Substrate ◽  
Different Temperatures ◽  
Test Cells ◽  
Substrate Moisture ◽  
Phase Transition Zone

The influence of moisture content on substrate thermal conductivity at different temperatures was investigated for four different commercially available substrates for green roofs. In the unfrozen state, as moisture content increased, thermal conductivity increased linearly. In the phase transition zone between +5 and −10 °C, as temperature decreased, thermal conductivity increased sharply during the transition from water to ice. When the substrate was frozen, thermal conductivity varied exponentially with substrate moisture content prior to freezing. Power functions were found between thermal conductivity and temperature. Two equally sized, green roof test cells were constructed and tested to compare various roof configurations including a bare roof, varying media thickness for a green roof, and vegetation. The results show that compared with the bare roof, there is a 75% reduction in the interior temperature’s amplitude for the green roof with 150 mm thick substrate. When a sedum mat was added, there was a 20% reduction in the amplitude of the inner temperature as compared with the cell without a sedum mat.

Measurement of indoor environmental parameters and analysis of the condensation phenomenon in urban utility tunnels

2022 ◽  
pp. 1420326X2110564
Author(s):  
Chuanmin Tai ◽  
Guansan Tian ◽  
Wenjun Lei
Keyword(s):  
Water Supply ◽  
Surface Temperature ◽  
Air Temperature ◽  
Natural Ventilation ◽  
Environmental Parameters ◽  
Dew Point ◽  
Control Mode ◽  
Safe Management ◽  
Environmental Test ◽  
Water Supply Pipeline

Condensation is a major issue in the safe operation of utility tunnels. To address the condensation problem, the indoor air temperature, relative humidity (RH) and surface temperature in an urban utility tunnel in Jining were continuously measured, and the condensation conditions were surveyed and analysed. The results indicated that under natural ventilation conditions, the air temperature in the comprehensive cabin varied from 23.4°C to 24.5°C, the RH fluctuated between 86.4% and 95.3%, and the corresponding air dew point temperature (DPT) remained in the range of 22.2°C–22.9°C. The surface temperature of the water supply pipeline ranged from 17.8°C to 18.5°C, which was far lower than the DPT in the tunnel, resulting in serious condensation. A water supply pipeline with an anti-condensation design was developed based on environmental test data. A 25-mm-thick rubber plastic sponge insulation layer was used to thermally insulate the water supply pipeline, preventing further dew condensation. Furthermore, mechanical ventilation had little effect on reducing the RH in the tunnel and may actually cause dew condensation; therefore, a ventilation control mode was proposed in this study. These results are expected to provide basic data for further research and reference for the safe management of utility tunnels.

scholarly journals Model research on the influence of green roofs on environmental parameters in urban agglomerations

2018 ◽  
Vol 45 ◽  
pp. 00094 ◽  
Author(s):  
Dariusz Suszanowicz
Keyword(s):  
Heavy Metals ◽  
Urban Areas ◽  
Air Pollutants ◽  
Green Roof ◽  
Soil Layer ◽  
Environmental Parameters ◽  
Green Roofs ◽  
Field Studies ◽  
Air Pollutant ◽  
Laboratory Scale

This study presents features of green roofs in urban areas with a particular emphasis on the filtration of air pollutants, heavy metals removal, reduction of rainwater runoff from roof surfaces and thermal insulation. To carry out field studies on the influence of green roofs on the environment in urban areas, two green roof models on a laboratory scale were used. The observations of the prepared green roof models made during the summer, autumn and winter confirmed the extremely beneficial effect of this type of roof for the elimination of air pollutant, heavy metals, and particulate matter. The observations also confirmed that plants on a green roof growing on a soil layer absorb an average of 74% of rain water and then allow it to evaporate. The selection of plants for green roofs should mainly focus on how effectively they improve urban environmental parameters and remove air pollutants. The results of the study of the two green roof models on a laboratory scale are necessary to work out the parameters of layers of the roof and select the most appropriate plants for the reference research object on the roof of one of buildings of the University of Opole.

scholarly journals Determination of the Physical, Chemical, and Hydraulic Characteristics of Locally Available Materials for Formulating Extensive Green Roof Substrates

2015 ◽  
Vol 25 (6) ◽  
pp. 774-784 ◽  
Author(s):  
Nikolaos Ntoulas ◽  
Panayiotis A. Nektarios ◽  
Thomais-Evelina Kapsali ◽  
Maria-Pinelopi Kaltsidi ◽  
Liebao Han ◽  
...  
Keyword(s):  
Particle Size ◽  
Moisture Content ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Green Roof ◽  
Organic Amendments ◽  
Green Roofs ◽  
N Leaching ◽  
Extensive Green Roof ◽  
Second Stage

Several locally available materials were tested to create an optimized growth substrate for arid and semiarid Mediterranean extensive green roofs. The study involved a four-step screening procedure. At the first step, 10 different materials were tested including pumice (Pum), crushed tiles grade 1–2 mm (T1–2), 2–4 mm (T2–4), 5–8 mm (T5–8), 5–16 mm (T5–16), and 4–22 mm (T4–22); crushed bricks of either 2–4 mm (B2–4) or 2–8 mm (B2–8); a thermally treated clay (TC); and zeolite (Zeo). All materials were tested for their particle size distribution, pH, and electrical conductivity (EC). The results were compared for compliance with existing guidelines for extensive green roof construction. From the first step, the most promising materials were shown to include Pum, Zeo, T5–8, T5–16, and TC, which were then used at the second stage to develop mixtures between them. Tests at the second stage included particle size distribution and moisture potential curves. Pumice mixed with TC provided the best compliance with existing guidelines in relation to particle size distribution, and it significantly increased moisture content compared with the mixes of Pum with T5–8 and T5–16. As a result, from the second screening step, the best performing substrate was Pum mixed with TC and Zeo. The third stage involved the selection of the most appropriate organic amendment of the growing substrate. Three composts having different composition and sphagnum peat were analyzed for their chemical and physical characteristics. The composts were a) garden waste compost (GWC), b) olive (Olea europaea L.) mill waste compost (OMWC), and c) grape (Vitis vinifera L.) marc compost (GMC). It was found that the peat-amended substrate retained increased moisture content compared with the compost-amended substrates. The fourth and final stage involved the evaluation of the environmental impact of the final mix with the four different organic amendments based on their first flush nitrate nitrogen (NO3−-N) leaching potential. It was found that GWC and OMWC exhibited increased NO3−-N leaching that initially reached 160 and 92 mg·L−1 of NO3−-N for OMWC and GWC, respectively. By contrast, peat and GMC exhibited minimal NO3−-N leaching that was slightly above the maximum contaminant level of 10 mg·L−1 of NO3−-N (17.3 and 14.6 mg·L−1 of NO3−N for peat and GMC, respectively). The latter was very brief and lasted only for the first 100 and 50 mL of effluent volume for peat and GMC, respectively.

scholarly journals Applications of Extensive Green-roof Systems in Contributing to Sustainable Development in Densely Populated Cities: a Hong Kong Study

2011 ◽  
Vol 11 (1) ◽  
pp. 15-25 ◽  
Author(s):  
Vivian W. Y. Tam ◽  
Xiaoling Zhang ◽  
Winnie Lee ◽  
LY Shen
Keyword(s):  
Hong Kong ◽  
Air Temperature ◽  
Current Practice ◽  
Green Roof ◽  
Green Roofs ◽  
Existing Building ◽  
Extensive Green Roof ◽  
High Rise ◽  
Urban Greenery ◽  
Extensive Green Roofs

Developed cities such as Hong Kong are usually densely populated. Since the land is limited, high-rise buildings are constructed. When the building height becomes higher, air flow is reduced and heat is trapped among high-rise buildings. Air temperature will be greatly increased and air pollution becomes a serious problem. This creates a walled building problem. To reduce air temperature caused by the wall-effects, various methods have been developed in the previous studies. One typical method is the use of green roof systems. The application of extensive green roofs on the existing building rooftops has been recommended in Hong Kong since 2001. The advantage of this practice is that no additional floor area is required and it can also improve urban greenery. Although a green roof system has been introduced and adopted in Hong Kong since 2001, the emphasis is mainly given to the application of intensive green roofs for podium garden instead of extensive green roofs. It is considered valuable and necessary of the extensive green roofs for the buildings. This paper investigates the current practice of using extensive green roofs in Hong Kong. The constraints in applying extensive green roofs are investigated, which leads to studying the solutions for mitigating these constraints and improving the future development of the implementation.

scholarly journals Moisture Content of Extensive Green Roof Substrate and Growth Response of 15 Temperate Plant Species during Dry Down

HortScience ◽  
2011 ◽  
Vol 46 (3) ◽  
pp. 518-522 ◽  
Author(s):  
Jennifer M. Bousselot ◽  
James E. Klett ◽  
Ronda D. Koski
Keyword(s):  
Moisture Content ◽  
Plant Species ◽  
Green Roof ◽  
Green Roofs ◽  
Herbaceous Plant ◽  
Herbaceous Species ◽  
Extensive Green Roof ◽  
Dry Down ◽  
Porous Soils ◽  
Extensive Green Roofs

Success of extensive green roof vegetation depends primarily on associated plant species' ability to survive the low moisture content of the substrate. As a result of the well-drained nature of the substrate, plants adaptable to dry, porous soils are primarily used in extensive green roof applications. Although Sedum species have dominated the plant palette for extensive green roofs, there is growing interest in expanding the plant list for extensive green roof systems. To effectively select suitable plants, species need to be evaluated in terms of their response to gradual and prolonged dry down of the substrate. A study to determine the relative rates of dry down for 15 species was conducted in greenhouse trials. During dry downs that extended over 5 months, the substrate of succulent and herbaceous species dried down at different rates. The change in moisture content of the substrate was not consistent among succulent and herbaceous plant species during the initial 18 d of dry down. Despite differences in rate of dry down, the succulent species, as a group, maintained viable foliage for over five times longer than the herbaceous species. The revival rates of the succulent species were nearly double those of the herbaceous species. Therefore, not only are succulent species more likely to survive during periods of drought, but these species are more likely to resume growth soon after water is again made available.

scholarly journals Thermal Behavior of Green Roofs Applied to Tropical Climate

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Grace Tibério Cardoso ◽  
Francisco Vecchia
Keyword(s):  
Thermal Behavior ◽  
Air Temperature ◽  
Water Reuse ◽  
Building Materials ◽  
Time Lag ◽  
Green Roof ◽  
Green Roofs ◽  
Run Off ◽  
Cover Systems ◽  
Dry Climates

The main goal of this paper is to present results on an experimental field about the green roofs thermal behavior, compared to other traditional roof covering systems. On the one hand, it intends to describe shortly the constructive system of a green roof with a lightweight building system, which has a sustainable building materials character and, on the other, it worries with the water reuse and with the run-off delay. The main methodological procedure adopted to study the thermal behavior of green roof was installing thermocouples to collect surface temperatures and indoor air, later comparing them with existing prototypes in an experimental plot. The thermal behavior analysis of cover systems was assessed by a representative episode of the climate fact, based on the dynamic climate approach. The experimental results from internal air temperature measurements show that the green roofs applied to warm and dry climates also provide an interesting time lag with surface and internal air temperature reduction.

scholarly journals Moisture content of cereals at harvesting time by comparing microclimate values and standard weather data

1993 ◽  
Vol 41 (3) ◽  
pp. 167-178
Author(s):  
A.J. Atzema
Keyword(s):  
Moisture Content ◽  
Surface Temperature ◽  
Air Temperature ◽  
Weather Conditions ◽  
Dew Point ◽  
Weather Data ◽  
Daily Cycle ◽  
The Difference ◽  
High Equilibrium ◽  
Screen House

The moisture content of wheat and barley together with the weather elements were measured at 3 different experimental sites in the Netherlands in 1990-91. The difference in the dew point temperature in the screen[house] and in the field was small. However, the differences between air temperature in the screen and those at different heights in wheat and in barley stands were considerable. In daytime the surface temperature of barley was higher than that of wheat under the same weather conditions as a result of a higher absorbtion coefficient. Both for wheat and barley, the maximum difference between the calculated moisture content was 0.5%, using the air temperature at 1.5 m height from the nearest standard weather station and the surface temperature of the spikes. Barley had a greater daily cycle in the moisture content of the grains than wheat as a result of a high equilibrium moisture content during the night and a low one in daytime.

scholarly journals Role of drainage layer on green roofs in limiting the runoff of rainwater from urbanized areas

2019 ◽  
Vol 41 (1) ◽  
pp. 12-18 ◽  
Author(s):  
Anna M. Baryła
Keyword(s):  
Moisture Content ◽  
Green Roof ◽  
Initial Moisture Content ◽  
Green Roofs ◽  
Climatic Conditions ◽  
Column Studies ◽  
Initial State ◽  
Drainage Layer ◽  
Urbanized Areas ◽  
Substrate Moisture

Abstract Green roofs play a significant role in sustainable drainage systems. They form absorbent surfaces for rainwater, which they retain with the aid of profile and plants. Such roofs therefore take an active part in improving the climatic conditions of a city and, more broadly, the water balance of urbanized areas. One of the factors influencing the hydrological efficiency of green roofs is the drainage layer. In the article, column studies were carried out under field conditions involving the comparison of the retention abilities of two aggregates serving as the drainage layer of green roofs, i.e. Leca® and quartzite grit. The average retention of the substrate was 48%; for a 5 cm drainage layer of Leca® retention was 57%, for a 10 cm layer of Leca average retention was 61%. For a 5 cm layer of quartzite grit average retention was 50%, for 10 cm layer of quartzite grit 53%. The highest retention was obtained for the column with the substrate and 10-centimeter layer of Leca®. At the same time, it was shown that Leca® is a better retention material than quartzite grit. The initial state of substrate moisture content from a green roof appears to be a significant factor in reducing rainfall runoff from a green roof; the obtained values of initial moisture content made for a higher correlation than the antecedent dry weather period.

scholarly journals In-situ monitoring of energetic and hydrological performance of a semi-intensive green roof and a white roof during a heatwave event in the UK

2019 ◽  
Vol 30 (1) ◽  
pp. 56-69 ◽  
Author(s):  
Yangang Xing ◽  
Phil Jones
Keyword(s):  
Air Temperature ◽  
Indoor Air ◽  
Performance Monitoring ◽  
Green Roof ◽  
Weather Conditions ◽  
Green Roofs ◽  
In Situ Monitoring ◽  
Runoff Reduction ◽  
Peak Runoff ◽  
The Uk

Due to the increasing magnitude and high frequency of urban heatwaves, recently, there has been a surge of interest in the reflective roofs and the vegetative green roofs. Along with the rising temperature, there are also more frequent droughts and rainfall which have led to wider changes in weather conditions subsequently affecting the performance of green roofs and white roofs. However, there is still a lack of research in comparing dynamic energetic and hydrological performance of green roof and white roofs during heatwave events. This paper introduces a newly constructed outdoor test rig (installed with a semi-intensive green roof and an aluminium white roof) and a few initial monitoring results. The hydrological performance monitoring results showed that, although a noticeable peak runoff reduction of the white roof was observed, more significant water retention of green roofs had been established. The energetic performance monitoring results indicated that the green roof performed better than the white roof during the heatwave event reducing solar heat gains by 76% during day time, improving U-value by 28% and reducing indoor air temperature by 2.5°C. The peak indoor air temperature reduction in the green roof space occurred during late afternoons (around 7 pm).

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