Passive strategies for acclimatization of buildings have been studied by several authors in many countries, especially the evaporative and radiant cooling techniques. Fiber cement tiles are very common in popular cons...Passive strategies for acclimatization of buildings have been studied by several authors in many countries, especially the evaporative and radiant cooling techniques. Fiber cement tiles are very common in popular constructions due to their low cost. However, they have over twice of the value thermal transmittance indicated to this bioclimatic zone according to Brazilian guidelines. The objective is to present an alternative to reduce high temperatures on fiber cement tiles. In this paper, the monitoring of passive cooling of roofing during the spring season in a city with subtropical climate is described. Single and combined reflective and evaporative cooling systems were studied in different environmental conditions. Internal surface temperatures of tiles were monitored together with weather variables. Results show a decrease of about 6 ℃, 9 ℃, 10 ℃ and 11 ℃ as compared to the original tiles according to environment conditions and the combined passive cooling techniques. These results allow for the conclusion that the use of passive cooling techniques opens up new possibilities to attenuate the internal surface temperatures of tiles and to consequently decrease the roofing solar heat gain into buildings, thus, providing less air cooling energy consumption.展开更多
An experimental investigation of passive cooling buildings has been carried out for a typical summer days extended from July to December of Baghdad in Iraq. Six independent chambers were designed and constructed for d...An experimental investigation of passive cooling buildings has been carried out for a typical summer days extended from July to December of Baghdad in Iraq. Six independent chambers were designed and constructed for different roof constructions. Night ventilation has been applied to study the possibility of reducing air temperature in buildings by testing different air changes per hour extended from 5 to 30. Measurements outside chambers including air temperature; relative humidity and solar radiation were achieved, while surface temperature and air temperature inside the chambers were recorded. The results show that the air temperature can be decreased with a range from 3 ℃ to 6 ℃ when using 50 mm polystyrene. This decrease can further be lowered by 2 ℃ to 4 ℃ if night ventilation of change per hours in buildings is allowed. The reduction in air temperature can be reduced to 5 ℃ by combination of external night ventilation and white paint.展开更多
Experimental research was conducted to study the structural behaviors of a steel roof truss model without fire-proof coating under pool fire conditions. The data of temperature distribution and displacements of typica...Experimental research was conducted to study the structural behaviors of a steel roof truss model without fire-proof coating under pool fire conditions. The data of temperature distribution and displacements of typical members were obtained. It is found that the temperature distribution of environment inside the structure, which is found to be in accordance with the multi-zone model with height, has a decisive effect on the tempera^tre evolution of steel members. Besides, it can also be observed that due to the restriction and coordination among the truss members in the localized fire, the maximum relative deflection, which occurs at the mid-span of the top chord, is relatively slight and has not exceeded 1 mm under experimental conditions. On the other hand, the column experiences a notable thermal expansion during the test. Then, a finite element model is presented and validated by the test results.展开更多
Analyzing observations of wintertime air temperature in both indoor and outdoor surroundings in Kunming, a city lying in low latitudes, characteristics of temperature and humidity have been studied for the interior of...Analyzing observations of wintertime air temperature in both indoor and outdoor surroundings in Kunming, a city lying in low latitudes, characteristics of temperature and humidity have been studied for the interior of rooms facing north-south under different weather conditions. Significant warming effect has been identified in terms of lowest and daily-mean indoor temperature in the area of Kunming. The heating amplitude ranges from 7.7C to 10.0C and from 4.6C to 5.8C for the interior part of rooms facing the south and from 4.6C to 7.0C and from 1.3C to 4.4C for the interior part of rooms facing the north, respectively for the two elements. The highest air temperature is higher indoor than outdoor for rooms facing the south, but otherwise is usually true for rooms facing the north. Additional findings point out that buildings not only help maintain relatively warm indoor temperature but delay its variation. The diurnal cycle of temperature indoor is smaller and ranges by 40% ~ 48% for south-facing rooms, and by 20% ~ 30% for north-facing rooms, than outdoor, and the highest temperature is about 2 hours late inside the room than outside. It shows how inertly indoor temperature varies. The work also finds that relative humidity is less indoor in southward rooms than in northward ones and difference is the largest on fine days but the smallest when it is overcast. For the diurnal variation, the indoor relative humidity is large at nighttime with small amplitude but small during daytime with large amplitude. The above-presented results can be served as scientific foundation for more research on climate in low-latitude cities and rational design of urban architectures.展开更多
This work is part of a large experimental study on the distribution of internal temperatures in two similar test cells, but with different systems of coverage. The main goal of this paper is to present results on an e...This work is part of a large experimental study on the distribution of internal temperatures in two similar test cells, but with different systems of coverage. The main goal of this paper is to present results on an experimental field to determine the influence of solar radiation on the internal environmental conditions of different roof systems. Dry bulb temperature and internal surface temperatures were measured in two test cells with different roof systems （green roof and conventional ceramic roof）. Their thermal performances were compared on days with differing air mass domain, based on dynamic climatic approach. This research was based on the spatial and temporal approaches of dynamic climatology, from the climatic regime of the city of Itirapina, S^o Paulo State, analysed as representative episodes. Climatic data were provided by an automatic weather station and verified by satellite imagery, and the internal temperatures of the cells were collected by thermocouples installed on the surfaces of ceilings, floors, walls, and suspended inside the buildings. The results indicate that the solar radiation is mainly responsible for the great variations in temperature and its impact on indoor environments, since there were great differences in temperature inside comparing the two days of the experiment. This refutes the notion that the outside temperature is responsible for daily variations in temperature inside buildings.展开更多
lraq locates in hot arid region （30 °N-37 °N）, where the hot summer season is very long and the ambient temperature is about 50 ℃. Cooling of building needs A/C （air-conditioning） system which consumes ...lraq locates in hot arid region （30 °N-37 °N）, where the hot summer season is very long and the ambient temperature is about 50 ℃. Cooling of building needs A/C （air-conditioning） system which consumes more than 60% of the total electricity supplied to residential building. So, there is really need to minimize the energy consumption by enhancement the performance of Iraqi buildings using passive house technique. This paper presents the thermal performance ofa Passivhaus model built in Kirkuk （35 °N）. The design depends on the using of suitable materials, sufficient insulation, well airtightness and underground air cooling. The experimental measurements take in consideration several parameters like ambient temperature, solar radiation, orientation of the building and duration. The results give good indication of the benefit of using this technique of passive cooling system in Iraqi residential buildings. The indoor temperature could be reduced to 30 ℃, while, the energy consumption for cooling could be saved up to 80%.展开更多
This article aims to assess the spatial distribution of the IST （internal surface temperatures） in the ceiling and DBT （dry bulb temperatures） of a LGR （light green roof） in a test cell. Cover systems known as g...This article aims to assess the spatial distribution of the IST （internal surface temperatures） in the ceiling and DBT （dry bulb temperatures） of a LGR （light green roof） in a test cell. Cover systems known as green roofs have the potential to retain rainwater and help reduce runoff. However, the characteristic considered in this work is the insulation capacity of this kind of coverage. To evaluate the spatial distribution of temperatures in an environment with light green roof, we proposed a new method for acquisition of series of climatological data and temperatures according to spatial and temporal approaches of dynamic climatology. Climatological data were provided by an automatic weather station and temperatures were collected in a test cell with light green roof. The spatial distribution of surface temperatures and internal air temperature （DBT） are based on the concepts of a climatic episode and typical experimental day from the study of the dynamic climatology. The results led to the conclusion that the light green roof has a balanced spatial distribution of the IST and of the internal air temperature （DBT）, i.e., without substantial variations over the day. The new methodology also showed the importance of specifying the location of the sensors and automatic weather station in experimental studies on the thermal behaviour of buildings.展开更多
文摘Passive strategies for acclimatization of buildings have been studied by several authors in many countries, especially the evaporative and radiant cooling techniques. Fiber cement tiles are very common in popular constructions due to their low cost. However, they have over twice of the value thermal transmittance indicated to this bioclimatic zone according to Brazilian guidelines. The objective is to present an alternative to reduce high temperatures on fiber cement tiles. In this paper, the monitoring of passive cooling of roofing during the spring season in a city with subtropical climate is described. Single and combined reflective and evaporative cooling systems were studied in different environmental conditions. Internal surface temperatures of tiles were monitored together with weather variables. Results show a decrease of about 6 ℃, 9 ℃, 10 ℃ and 11 ℃ as compared to the original tiles according to environment conditions and the combined passive cooling techniques. These results allow for the conclusion that the use of passive cooling techniques opens up new possibilities to attenuate the internal surface temperatures of tiles and to consequently decrease the roofing solar heat gain into buildings, thus, providing less air cooling energy consumption.
文摘An experimental investigation of passive cooling buildings has been carried out for a typical summer days extended from July to December of Baghdad in Iraq. Six independent chambers were designed and constructed for different roof constructions. Night ventilation has been applied to study the possibility of reducing air temperature in buildings by testing different air changes per hour extended from 5 to 30. Measurements outside chambers including air temperature; relative humidity and solar radiation were achieved, while surface temperature and air temperature inside the chambers were recorded. The results show that the air temperature can be decreased with a range from 3 ℃ to 6 ℃ when using 50 mm polystyrene. This decrease can further be lowered by 2 ℃ to 4 ℃ if night ventilation of change per hours in buildings is allowed. The reduction in air temperature can be reduced to 5 ℃ by combination of external night ventilation and white paint.
基金Project(50706059) supported by the National Natural Science Foundation of ChinaProject(HZ2009-KF05) supported by Open Fund of State Key Laboratory of Fire Science of University of Science and Technology in ChinaProject supported by the Fundamental Research Funds for the Central Universities of China
文摘Experimental research was conducted to study the structural behaviors of a steel roof truss model without fire-proof coating under pool fire conditions. The data of temperature distribution and displacements of typical members were obtained. It is found that the temperature distribution of environment inside the structure, which is found to be in accordance with the multi-zone model with height, has a decisive effect on the tempera^tre evolution of steel members. Besides, it can also be observed that due to the restriction and coordination among the truss members in the localized fire, the maximum relative deflection, which occurs at the mid-span of the top chord, is relatively slight and has not exceeded 1 mm under experimental conditions. On the other hand, the column experiences a notable thermal expansion during the test. Then, a finite element model is presented and validated by the test results.
文摘Analyzing observations of wintertime air temperature in both indoor and outdoor surroundings in Kunming, a city lying in low latitudes, characteristics of temperature and humidity have been studied for the interior of rooms facing north-south under different weather conditions. Significant warming effect has been identified in terms of lowest and daily-mean indoor temperature in the area of Kunming. The heating amplitude ranges from 7.7C to 10.0C and from 4.6C to 5.8C for the interior part of rooms facing the south and from 4.6C to 7.0C and from 1.3C to 4.4C for the interior part of rooms facing the north, respectively for the two elements. The highest air temperature is higher indoor than outdoor for rooms facing the south, but otherwise is usually true for rooms facing the north. Additional findings point out that buildings not only help maintain relatively warm indoor temperature but delay its variation. The diurnal cycle of temperature indoor is smaller and ranges by 40% ~ 48% for south-facing rooms, and by 20% ~ 30% for north-facing rooms, than outdoor, and the highest temperature is about 2 hours late inside the room than outside. It shows how inertly indoor temperature varies. The work also finds that relative humidity is less indoor in southward rooms than in northward ones and difference is the largest on fine days but the smallest when it is overcast. For the diurnal variation, the indoor relative humidity is large at nighttime with small amplitude but small during daytime with large amplitude. The above-presented results can be served as scientific foundation for more research on climate in low-latitude cities and rational design of urban architectures.
文摘This work is part of a large experimental study on the distribution of internal temperatures in two similar test cells, but with different systems of coverage. The main goal of this paper is to present results on an experimental field to determine the influence of solar radiation on the internal environmental conditions of different roof systems. Dry bulb temperature and internal surface temperatures were measured in two test cells with different roof systems （green roof and conventional ceramic roof）. Their thermal performances were compared on days with differing air mass domain, based on dynamic climatic approach. This research was based on the spatial and temporal approaches of dynamic climatology, from the climatic regime of the city of Itirapina, S^o Paulo State, analysed as representative episodes. Climatic data were provided by an automatic weather station and verified by satellite imagery, and the internal temperatures of the cells were collected by thermocouples installed on the surfaces of ceilings, floors, walls, and suspended inside the buildings. The results indicate that the solar radiation is mainly responsible for the great variations in temperature and its impact on indoor environments, since there were great differences in temperature inside comparing the two days of the experiment. This refutes the notion that the outside temperature is responsible for daily variations in temperature inside buildings.
文摘lraq locates in hot arid region （30 °N-37 °N）, where the hot summer season is very long and the ambient temperature is about 50 ℃. Cooling of building needs A/C （air-conditioning） system which consumes more than 60% of the total electricity supplied to residential building. So, there is really need to minimize the energy consumption by enhancement the performance of Iraqi buildings using passive house technique. This paper presents the thermal performance ofa Passivhaus model built in Kirkuk （35 °N）. The design depends on the using of suitable materials, sufficient insulation, well airtightness and underground air cooling. The experimental measurements take in consideration several parameters like ambient temperature, solar radiation, orientation of the building and duration. The results give good indication of the benefit of using this technique of passive cooling system in Iraqi residential buildings. The indoor temperature could be reduced to 30 ℃, while, the energy consumption for cooling could be saved up to 80%.
文摘This article aims to assess the spatial distribution of the IST （internal surface temperatures） in the ceiling and DBT （dry bulb temperatures） of a LGR （light green roof） in a test cell. Cover systems known as green roofs have the potential to retain rainwater and help reduce runoff. However, the characteristic considered in this work is the insulation capacity of this kind of coverage. To evaluate the spatial distribution of temperatures in an environment with light green roof, we proposed a new method for acquisition of series of climatological data and temperatures according to spatial and temporal approaches of dynamic climatology. Climatological data were provided by an automatic weather station and temperatures were collected in a test cell with light green roof. The spatial distribution of surface temperatures and internal air temperature （DBT） are based on the concepts of a climatic episode and typical experimental day from the study of the dynamic climatology. The results led to the conclusion that the light green roof has a balanced spatial distribution of the IST and of the internal air temperature （DBT）, i.e., without substantial variations over the day. The new methodology also showed the importance of specifying the location of the sensors and automatic weather station in experimental studies on the thermal behaviour of buildings.
