Pub Date : 2006-02-01DOI: 10.1191/0143624406bt141tn
M. Asif, T. Muneer
Sustainability of building construction and its services is increasingly drawing attention. In this respect CIBSE has issued a number of calls to industry. Solar water heating systems are now economically competitive and are being used throughout the world. Following earlier work of the present authors on the life cycle assessment (LCA) for building components,1,2 this work presents a monetary, energy usage and environmental impact assessment for solar water heaters. It has been shown herein that for a developing country like Pakistan where large amounts of hot water are required within industry, solar water heating offers favorable payback periods on each of the above three counts. It has been estimated that under the tested conditions, the embodied energy payback period for the plain and finned heater is equivalent to 185 days and 169 days respectively. It has also been found that the amount of carbon released during the construction process of plain and finned water heaters is 27.9 kg and 29.7 kg respectively. Annual carbon saving for the plain and finned water heaters has been calculated to be equivalent to 59.5 kg and 69.6 kg respectively, which in turn gives a carbon payback period of 156 days and 171 days. The monetary payback period for the plain and finned heater has been found to be equivalent to 6.7 years and 6.1 years respectively.
{"title":"Life cycle assessment of built-in-storage solar water heaters in Pakistan","authors":"M. Asif, T. Muneer","doi":"10.1191/0143624406bt141tn","DOIUrl":"https://doi.org/10.1191/0143624406bt141tn","url":null,"abstract":"Sustainability of building construction and its services is increasingly drawing attention. In this respect CIBSE has issued a number of calls to industry. Solar water heating systems are now economically competitive and are being used throughout the world. Following earlier work of the present authors on the life cycle assessment (LCA) for building components,1,2 this work presents a monetary, energy usage and environmental impact assessment for solar water heaters. It has been shown herein that for a developing country like Pakistan where large amounts of hot water are required within industry, solar water heating offers favorable payback periods on each of the above three counts. It has been estimated that under the tested conditions, the embodied energy payback period for the plain and finned heater is equivalent to 185 days and 169 days respectively. It has also been found that the amount of carbon released during the construction process of plain and finned water heaters is 27.9 kg and 29.7 kg respectively. Annual carbon saving for the plain and finned water heaters has been calculated to be equivalent to 59.5 kg and 69.6 kg respectively, which in turn gives a carbon payback period of 156 days and 171 days. The monetary payback period for the plain and finned heater has been found to be equivalent to 6.7 years and 6.1 years respectively.","PeriodicalId":272488,"journal":{"name":"Building Services Engineering Research and Technology","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124993427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-02-01DOI: 10.1191/0143624406bt142oa
D. Etheridge, K. Murphy, David Reay
Air conditioning is now seen as a new and major contributor to CO2 emissions in the UK. This is partly due to global warming and partly to the increased use of IT systems. A novel system for reducing or eliminating the need for air conditioning was developed to the proof-of-concept stage under an earlier project at the University of Nottingham. The system makes use of heat pipes to transfer heat into and out of a phase change material which is ‘frozen’ during the night and ‘melted’ during the day. This paper describes a number of concepts for ‘free cooling’, and the background to the current concept, before detailing field tests on the system that have recently been completed and which demonstrate its effectiveness under real operating conditions. Systems were installed in two offices and detailed monitoring of their performance was carried out during the summer months. On the basis of the results obtained it is concluded that the system functions very well and is practically and technically the most attractive of the available alternatives to air conditioning. The fact that it is suited to retrofitting in existing buildings means that both the potential market and the CO2reductions are large. Practical application: The paper describes a novel system that is intended to provide passive cooling in naturally ventilated buildings. The novelty lies in the use of heat pipes and a fan to enhance the heat transfer to and from the phase change material (PCM) and the air. That this has been successful is shown by the ability of the system to exercise a degree of control over the room air temperature that is comparable to that of a conventional airconditioning system. The review provided in the paper may also be of use to other workers on PCMs and night cooling of naturally ventilated buildings.
{"title":"A PCM/heat pipe cooling system for reducing air conditioning in buildings: review of options and report on field tests","authors":"D. Etheridge, K. Murphy, David Reay","doi":"10.1191/0143624406bt142oa","DOIUrl":"https://doi.org/10.1191/0143624406bt142oa","url":null,"abstract":"Air conditioning is now seen as a new and major contributor to CO2 emissions in the UK. This is partly due to global warming and partly to the increased use of IT systems. A novel system for reducing or eliminating the need for air conditioning was developed to the proof-of-concept stage under an earlier project at the University of Nottingham. The system makes use of heat pipes to transfer heat into and out of a phase change material which is ‘frozen’ during the night and ‘melted’ during the day. This paper describes a number of concepts for ‘free cooling’, and the background to the current concept, before detailing field tests on the system that have recently been completed and which demonstrate its effectiveness under real operating conditions. Systems were installed in two offices and detailed monitoring of their performance was carried out during the summer months. On the basis of the results obtained it is concluded that the system functions very well and is practically and technically the most attractive of the available alternatives to air conditioning. The fact that it is suited to retrofitting in existing buildings means that both the potential market and the CO2reductions are large. Practical application: The paper describes a novel system that is intended to provide passive cooling in naturally ventilated buildings. The novelty lies in the use of heat pipes and a fan to enhance the heat transfer to and from the phase change material (PCM) and the air. That this has been successful is shown by the ability of the system to exercise a degree of control over the room air temperature that is comparable to that of a conventional airconditioning system. The review provided in the paper may also be of use to other workers on PCMs and night cooling of naturally ventilated buildings.","PeriodicalId":272488,"journal":{"name":"Building Services Engineering Research and Technology","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133401360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-02-01DOI: 10.1191/0143624406bt135oa
D. Johnston, R. Lowe
This paper describes an approach that has been undertaken to improve the airtightness of a number of plasterboard-lined load-bearing masonry dwellings that were constructed in the early 1970s. Such dwellings are likely to be broadly representative of many of the dwellings that will be refurbished in the UK over the next decade or so. The airtightness of the dwellings was improved by undertaking a two-stage programme of general and targeted airtightness work, in parallel with a basic domestic refurbishment programme. The results illustrate that prior to the refurbishment, the dwellings were in a poor state of repair and had an air permeability of between 24 and 26 m3/h per m2 at 50 Pa, which is substantially in excess of the UK mean of 11.5 m3/h per m2 at 50 Pa.1 The condition of the dwellings also suggests that the air permeability of these dwellings is likely to be considerably higher than that which would have been experienced when they were first built. Following the refurbishment programme, it was possible to reduce the air permeability of these dwellings by almost 55%, to a mean of just over 11 m3/h per m2 at 50 Pa. The paper also identifies a number of factors that limited the effectiveness of the airtightness work. These factors included: wear and tear of the plasterboard-lining; detailing and workmanship during the refurbishment programme; and, the partial nature of the refurbishment programme. Had it been possible to address a number of these factors during the refurbishment programme, the authors are reasonably confident that an air permeability of less than 10 m3/h per m2 at 50 Pa could have been achieved in all of the dwellings. Despite the small size of the sample (only 12 dwellings were tested), the results suggest that the airtightness of existing plasterboard-lined load-bearing masonry dwellings can be improved to a level that is comparable to the current UK Building Regulations (Approved Document Part L1) requirement for new dwellings.2 Practical application: Airtightness is crucial to improving the energy performance of buildings. In the UK, existing dwellings tend to be very leaky compared to some of their international counterparts. The use of plasterboard-lining as an internal finish to external and party walls makes a significant contribution to this poor performance, particularly where it is not edge sealed. Air leakage measurements reported here for dwellings built in the 1970s suggest that if this construction is allowed to deteriorate, very high leakage rates may result. Considerations of the impact of choice of construction on future robustness and durability of airtightness of new housing is likely to be an important practicalconsideration, particularly for social housing providers. Separating the air barrier function from the plasterboard lining appears to provide a more reliable and probably more durable solution.3 The paper goes on to describe how injecting expanding polyurethane foam into the cavity between the inn
{"title":"Improving the airtightness of existing plasterboard-lined load-bearing masonry dwellings","authors":"D. Johnston, R. Lowe","doi":"10.1191/0143624406bt135oa","DOIUrl":"https://doi.org/10.1191/0143624406bt135oa","url":null,"abstract":"This paper describes an approach that has been undertaken to improve the airtightness of a number of plasterboard-lined load-bearing masonry dwellings that were constructed in the early 1970s. Such dwellings are likely to be broadly representative of many of the dwellings that will be refurbished in the UK over the next decade or so. The airtightness of the dwellings was improved by undertaking a two-stage programme of general and targeted airtightness work, in parallel with a basic domestic refurbishment programme. The results illustrate that prior to the refurbishment, the dwellings were in a poor state of repair and had an air permeability of between 24 and 26 m3/h per m2 at 50 Pa, which is substantially in excess of the UK mean of 11.5 m3/h per m2 at 50 Pa.1 The condition of the dwellings also suggests that the air permeability of these dwellings is likely to be considerably higher than that which would have been experienced when they were first built. Following the refurbishment programme, it was possible to reduce the air permeability of these dwellings by almost 55%, to a mean of just over 11 m3/h per m2 at 50 Pa. The paper also identifies a number of factors that limited the effectiveness of the airtightness work. These factors included: wear and tear of the plasterboard-lining; detailing and workmanship during the refurbishment programme; and, the partial nature of the refurbishment programme. Had it been possible to address a number of these factors during the refurbishment programme, the authors are reasonably confident that an air permeability of less than 10 m3/h per m2 at 50 Pa could have been achieved in all of the dwellings. Despite the small size of the sample (only 12 dwellings were tested), the results suggest that the airtightness of existing plasterboard-lined load-bearing masonry dwellings can be improved to a level that is comparable to the current UK Building Regulations (Approved Document Part L1) requirement for new dwellings.2 Practical application: Airtightness is crucial to improving the energy performance of buildings. In the UK, existing dwellings tend to be very leaky compared to some of their international counterparts. The use of plasterboard-lining as an internal finish to external and party walls makes a significant contribution to this poor performance, particularly where it is not edge sealed. Air leakage measurements reported here for dwellings built in the 1970s suggest that if this construction is allowed to deteriorate, very high leakage rates may result. Considerations of the impact of choice of construction on future robustness and durability of airtightness of new housing is likely to be an important practicalconsideration, particularly for social housing providers. Separating the air barrier function from the plasterboard lining appears to provide a more reliable and probably more durable solution.3 The paper goes on to describe how injecting expanding polyurethane foam into the cavity between the inn","PeriodicalId":272488,"journal":{"name":"Building Services Engineering Research and Technology","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122023536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-02-01DOI: 10.1191/0143624406bt144oa
Lt T. Wong, P. Hui
Skin pain and burns at an elevated skin layer temperature due to incident heat flux could be used to evaluate thermal hazards for some enclosed fire environments and mathematical expressions were proposed in literature for fire safety evaluations. In this work, a mathematical model for determining the skin layer temperature due to incident radiant heat flux is examined with experimental verification. Heat balance on the skin layer due to the heat flux and conductive heat transfer through it is considered. Specifically, the skin layer temperature at the head portion of an artificial thermal manikin was measured at certain incident radiant heat flux and compared with that calculated from the mathematical model. The results showed that the predictions were slightly higher than the measured values and the mathematical model would be useful in hazard assessment for some fire environments involving exposure of humans to a thermal radiation. Practical application: This paper presents the temperature measurement at a depth of 0.1 mm under the skin of an artificial thermal manikin’s head portion exposed to a vertical heated surface of 699 K in two orientations: facing and sideways to the surface. The result could be a useful source of information for the verification of any classical radiation model application to fire safety designs regarding heat exposure of the head portion of a person to heated surfaces.
{"title":"Experimental verification of a thermal radiation model for humanskin heat exposure","authors":"Lt T. Wong, P. Hui","doi":"10.1191/0143624406bt144oa","DOIUrl":"https://doi.org/10.1191/0143624406bt144oa","url":null,"abstract":"Skin pain and burns at an elevated skin layer temperature due to incident heat flux could be used to evaluate thermal hazards for some enclosed fire environments and mathematical expressions were proposed in literature for fire safety evaluations. In this work, a mathematical model for determining the skin layer temperature due to incident radiant heat flux is examined with experimental verification. Heat balance on the skin layer due to the heat flux and conductive heat transfer through it is considered. Specifically, the skin layer temperature at the head portion of an artificial thermal manikin was measured at certain incident radiant heat flux and compared with that calculated from the mathematical model. The results showed that the predictions were slightly higher than the measured values and the mathematical model would be useful in hazard assessment for some fire environments involving exposure of humans to a thermal radiation. Practical application: This paper presents the temperature measurement at a depth of 0.1 mm under the skin of an artificial thermal manikin’s head portion exposed to a vertical heated surface of 699 K in two orientations: facing and sideways to the surface. The result could be a useful source of information for the verification of any classical radiation model application to fire safety designs regarding heat exposure of the head portion of a person to heated surfaces.","PeriodicalId":272488,"journal":{"name":"Building Services Engineering Research and Technology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125384793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-02-01DOI: 10.1191/0143624406bt143oa
S. Younes, T. Muneer
Simple radiation estimation models using meteorologically observed input parameters are often used in the applications requiring rough estimations of solar horizontal radiation. One of the parameters employed, cloud cover, is widely available from multiple regional and national weather stations. Kasten and Czeplak, Muneer and Gul, and Lam and Li, have proposed cloud-based models for the estimation of global and diffuse horizontal irradiance. In the current study, three new cloud-based models have been proposed. To compare the validity of the above models, statistical indicators have been developed for assessing the accuracy of estimation of global, diffuse and beam horizontal irradiance. The slope of the best fit line and the coefficient of determination between measured and calculated values, mean bias error, and root mean square error were calculated. In addition, the kurtosis and skewness of error histograms were also obtained. These parameters were used to obtain accuracy indicators for the models under validation. It was concluded that the proposed models outperformed the Kasten / Czeplak, and Lam / Li models, in both their original and modified forms. Practical application: Solar radiation data is an essential part of designing passive and active solar systems in building services. However, the solar radiation data is not always measured at the desired location, but other meteorological data are more available, therefore, tools have been developed to estimate the solar radiation from other measured parameters such as cloud cover. The models that are proposed are more accurate than their predecessors are, and provide global, beam and diffuse horizontal irradiance estimations. List of symbols
{"title":"Improvements in solar radiation models based on cloud data","authors":"S. Younes, T. Muneer","doi":"10.1191/0143624406bt143oa","DOIUrl":"https://doi.org/10.1191/0143624406bt143oa","url":null,"abstract":"Simple radiation estimation models using meteorologically observed input parameters are often used in the applications requiring rough estimations of solar horizontal radiation. One of the parameters employed, cloud cover, is widely available from multiple regional and national weather stations. Kasten and Czeplak, Muneer and Gul, and Lam and Li, have proposed cloud-based models for the estimation of global and diffuse horizontal irradiance. In the current study, three new cloud-based models have been proposed. To compare the validity of the above models, statistical indicators have been developed for assessing the accuracy of estimation of global, diffuse and beam horizontal irradiance. The slope of the best fit line and the coefficient of determination between measured and calculated values, mean bias error, and root mean square error were calculated. In addition, the kurtosis and skewness of error histograms were also obtained. These parameters were used to obtain accuracy indicators for the models under validation. It was concluded that the proposed models outperformed the Kasten / Czeplak, and Lam / Li models, in both their original and modified forms. Practical application: Solar radiation data is an essential part of designing passive and active solar systems in building services. However, the solar radiation data is not always measured at the desired location, but other meteorological data are more available, therefore, tools have been developed to estimate the solar radiation from other measured parameters such as cloud cover. The models that are proposed are more accurate than their predecessors are, and provide global, beam and diffuse horizontal irradiance estimations. List of symbols","PeriodicalId":272488,"journal":{"name":"Building Services Engineering Research and Technology","volume":"AES-7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126506416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-02-01DOI: 10.1191/0143624406bt140oa
Gt Marewo, D. Henwood
The cooling system at the Harare International School uses a packed bed system for storing the coldness of the night-time to be used later for day-time airconditioning. A two-phase mathematical model is described for the packed bed which includes heat dispersion in the fluid, and heat loss to the environment. This is in contrast to other studies, where at least one of these terms is neglected to simplify the mathematical model. A numerical method for obtaining a solution is proposed and implemented. Using measured inlet temperatures, the measured and predicted outlet temperatures of the bed show good trend agreement. The differences in detail are examined through sensitivity analyses for both the heat convection transfer and air velocity. It is apparent that adjusting these parameters can increase the agreement between the predicted and measured data. A parametric study for heat storage with various materials and bed sizes is given, which indicates how the code may be used as a tool for improving design and operational parameters. Practical application: A mathematical model of a packed bed is described; the bed is made up of fluid flowing over solid material with heat interchange between the two. The solid material is idealized as spheres and the fluid temperature is assumed uniform in a cross-section of the bed. The model includes heat interchange between the bed and its surrounding environment and allows for time varying fluid velocity. The input data is the inlet temperature to the bed, which may be measured. The comparison with measured data may be helpful to anyone attempting to develop and test a similar model. The sensitivity tests give an understanding of the significance of some of the parameters involved. The Appendix gives a mathematical statement of the problem and an outline of an approach to developing computer code for a numerical solution.
哈拉雷国际学校(Harare International School)的冷却系统使用了一个填充床系统，用于储存夜间的寒冷，稍后用于白天的空调。描述了填料床的两相数学模型，该模型考虑了流体中的热分散和对环境的热损失。这与其他研究相反，在其他研究中，为了简化数学模型，至少忽略了这些术语中的一个。提出并实现了一种求解的数值方法。利用实测的进口温度，床层出口温度的测量值与预测值具有较好的一致性。通过对热对流传递和空气速度的敏感性分析，详细分析了这些差异。显然，调整这些参数可以提高预测数据与实测数据的一致性。对不同材料和床层尺寸的储热进行了参数化研究，表明该规范可以作为改进设计和操作参数的工具。实际应用:建立了填料床的数学模型;床是由流过固体材料的流体组成的，两者之间有热交换。固体物质被理想化为球体，流体温度被假设在床的横截面上是均匀的。该模型考虑了床层与周围环境之间的热交换，并考虑了流体速度随时间的变化。输入的数据是床的入口温度，这是可以测量的。与测量数据的比较可能对任何试图开发和测试类似模型的人有所帮助。灵敏度试验使人们了解所涉及的一些参数的重要性。附录给出了问题的数学陈述，并概述了为数值解开发计算机代码的方法。
{"title":"A mathematical model for supplying air-cooling for a building using a packed bed","authors":"Gt Marewo, D. Henwood","doi":"10.1191/0143624406bt140oa","DOIUrl":"https://doi.org/10.1191/0143624406bt140oa","url":null,"abstract":"The cooling system at the Harare International School uses a packed bed system for storing the coldness of the night-time to be used later for day-time airconditioning. A two-phase mathematical model is described for the packed bed which includes heat dispersion in the fluid, and heat loss to the environment. This is in contrast to other studies, where at least one of these terms is neglected to simplify the mathematical model. A numerical method for obtaining a solution is proposed and implemented. Using measured inlet temperatures, the measured and predicted outlet temperatures of the bed show good trend agreement. The differences in detail are examined through sensitivity analyses for both the heat convection transfer and air velocity. It is apparent that adjusting these parameters can increase the agreement between the predicted and measured data. A parametric study for heat storage with various materials and bed sizes is given, which indicates how the code may be used as a tool for improving design and operational parameters. Practical application: A mathematical model of a packed bed is described; the bed is made up of fluid flowing over solid material with heat interchange between the two. The solid material is idealized as spheres and the fluid temperature is assumed uniform in a cross-section of the bed. The model includes heat interchange between the bed and its surrounding environment and allows for time varying fluid velocity. The input data is the inlet temperature to the bed, which may be measured. The comparison with measured data may be helpful to anyone attempting to develop and test a similar model. The sensitivity tests give an understanding of the significance of some of the parameters involved. The Appendix gives a mathematical statement of the problem and an outline of an approach to developing computer code for a numerical solution.","PeriodicalId":272488,"journal":{"name":"Building Services Engineering Research and Technology","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130301370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-11-01DOI: 10.1191/0143624405bt139oa
R. Yao, K. Steemers, N. Baker
A simplified coupled thermal and airflow model has been developed by integrating the British Standard natural ventilation calculation method for a single zone within a four-node thermal resistance network model, which is called the thermal resistance ventilation model (TRV). By comparison of the results from the TRV with that of the ESP-r program, and subsequently tuning the TRV parameter values, good correlation can be obtained. A two-stage method is proposed for natural ventilation strategic design and analysis. The first stage calculates the constant air rate (CAR) and performs parametric studies in order to propose a design strategy and the appropriate opening area which satisfies thermal comfort. The second stage calculates the dynamic air rate (DAR) and internal temperature and performs analytic studies of the proposed design. An example case has been introduced using this two-stage process. It shows that the method proposed in this paper is simple and straightforward and it is suitable for the strategic design of natural ventilation. Furthermore, it demonstrates how the simplified method can be used to generate detailed and robust comfort data based on both an automatic and a behavioural control model. Practical appilcation: This paper describes a two-stage method to perform parametric and analytic studies of natural ventilation for summer cooling. This method is simple and straightforward, which is suitable for strategic design of natural ventilation. It demonstrates how the simplified method can be used to generate detailed and robust comfort data based on both automatic and behavioural control models.
{"title":"Strategic design and analysis method of natural ventilation for summer cooling","authors":"R. Yao, K. Steemers, N. Baker","doi":"10.1191/0143624405bt139oa","DOIUrl":"https://doi.org/10.1191/0143624405bt139oa","url":null,"abstract":"A simplified coupled thermal and airflow model has been developed by integrating the British Standard natural ventilation calculation method for a single zone within a four-node thermal resistance network model, which is called the thermal resistance ventilation model (TRV). By comparison of the results from the TRV with that of the ESP-r program, and subsequently tuning the TRV parameter values, good correlation can be obtained. A two-stage method is proposed for natural ventilation strategic design and analysis. The first stage calculates the constant air rate (CAR) and performs parametric studies in order to propose a design strategy and the appropriate opening area which satisfies thermal comfort. The second stage calculates the dynamic air rate (DAR) and internal temperature and performs analytic studies of the proposed design. An example case has been introduced using this two-stage process. It shows that the method proposed in this paper is simple and straightforward and it is suitable for the strategic design of natural ventilation. Furthermore, it demonstrates how the simplified method can be used to generate detailed and robust comfort data based on both an automatic and a behavioural control model. Practical appilcation: This paper describes a two-stage method to perform parametric and analytic studies of natural ventilation for summer cooling. This method is simple and straightforward, which is suitable for strategic design of natural ventilation. It demonstrates how the simplified method can be used to generate detailed and robust comfort data based on both automatic and behavioural control models.","PeriodicalId":272488,"journal":{"name":"Building Services Engineering Research and Technology","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125640191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-11-01DOI: 10.1191/0143624405bt133oa
D. Robinson, Andrew Stone
The radiant external environment may be described by two hemispheres, above and below the horizontal plane, which are discretized into a number of patches of known solid angle. Occlusions to these patches may be combined and represented as some patch fraction for which the radiant characteristics are defined by the dominant occlusion. By solving for radiant exchanges between each surface in a scene and its associated (un)occluded patches, we have a simplified radiosity algorithm (SRA). This paper describes the application of this SRA to solve for urban scale predictions of: (i) solar radiation; (ii) interior daylight; and (iii) longwave radiation. Comparisons of solar and daylight predictions with the ray-tracing program RADIANCE show that accurate results are achieved at a computational cost several orders of magnitude lower. Practical application: This paper describes a new model for predicting external irradiance (shortwave and longwave) and internal illuminance in an accurate and very efficient way, in a single computational module. This module may be incorporated into existing software to improve the quality of predictions from single building thermal simulations as well as emerging software for urban scale predictions of integrated resource (energy, water, waste) flows, for which the model was developed.
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Pub Date : 2005-11-01DOI: 10.1191/0143624405bt136oa
A. Wright, A. Young, S. Natarajan
More frequent hot summers in the UK under climate change could lead to increased discomfort in dwellings, but there is little published field data on internal summer temperatures. Temperatures were measured in four dwellings around south Manchester and five dwellings in London during the August 2003 heat wave. Resultant statistics and various comfort metrics indicated a high level of discomfort in most dwellings, particularly in London. Daily internal temperatures were shown to correlate strongly with a time-decaying function of daily outside temperatures. Day and night temperatures were shown to relate to the type of structure. It is concluded that if heat waves become more common, this would lead to increased discomfort, with implications for health, mortality and housing design. Practical application: The results presented in this paper show what actually happens to a sample of dwelling temperatures during a severe UK heat wave, and the consequences for comfort. Little has been published on this previously. The correlations between time-averaged outside temperatures, and internal temperatures, provide a method for predicting dwelling temperatures in the future in a warming climate, without the need for detailed simulation and including real occupancy effects such as window opening, which are difficult to simulate reliably. Since there were many excess deaths during the August 2003 heat wave, health is an important concern. Work by others on this issue has shown that mortality rate is correlated with a three-day moving average of outside temperature above a threshold. This moving average correlates closely with the type of time-averaged outside temperature used in the paper. It seems quite possible that a 3-day moving average is a good predictor of excess mortality because it is also a good predictor of internal building temperatures, due to the mediation of thermal mass. This provides an alternative, or additional, explanation to that which explains the mortality as the cumulative result of high external temperatures acting on the human body over a few days, without considering the effects of buildings.
{"title":"Dwelling temperatures and comfort during the August 2003 heat wave","authors":"A. Wright, A. Young, S. Natarajan","doi":"10.1191/0143624405bt136oa","DOIUrl":"https://doi.org/10.1191/0143624405bt136oa","url":null,"abstract":"More frequent hot summers in the UK under climate change could lead to increased discomfort in dwellings, but there is little published field data on internal summer temperatures. Temperatures were measured in four dwellings around south Manchester and five dwellings in London during the August 2003 heat wave. Resultant statistics and various comfort metrics indicated a high level of discomfort in most dwellings, particularly in London. Daily internal temperatures were shown to correlate strongly with a time-decaying function of daily outside temperatures. Day and night temperatures were shown to relate to the type of structure. It is concluded that if heat waves become more common, this would lead to increased discomfort, with implications for health, mortality and housing design. Practical application: The results presented in this paper show what actually happens to a sample of dwelling temperatures during a severe UK heat wave, and the consequences for comfort. Little has been published on this previously. The correlations between time-averaged outside temperatures, and internal temperatures, provide a method for predicting dwelling temperatures in the future in a warming climate, without the need for detailed simulation and including real occupancy effects such as window opening, which are difficult to simulate reliably. Since there were many excess deaths during the August 2003 heat wave, health is an important concern. Work by others on this issue has shown that mortality rate is correlated with a three-day moving average of outside temperature above a threshold. This moving average correlates closely with the type of time-averaged outside temperature used in the paper. It seems quite possible that a 3-day moving average is a good predictor of excess mortality because it is also a good predictor of internal building temperatures, due to the mediation of thermal mass. This provides an alternative, or additional, explanation to that which explains the mortality as the cumulative result of high external temperatures acting on the human body over a few days, without considering the effects of buildings.","PeriodicalId":272488,"journal":{"name":"Building Services Engineering Research and Technology","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130349435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-11-01DOI: 10.1191/0143624405bt127tn
S. Arthur, G. Wright
The past 10 years have witnessed significant changes in the way roof drainage systems are understood and designed. In particular, there has been a stepchange in the confidence with which siphonic roof drainage systems may be specified and expected to perform. These changes have occurred whilst urban drainage design in general has been revolutionized by wider acceptance of Sustainable Urban Drainage Systems and greater public concern regarding pluvial flooding within the context of climate change. This text considers, in detail, both how roof drainage systems are designed and how they should be expected to perform. Particular attention is drawn to weaknesses in accepted design methods. Consideration is also given to ‘innovative’ roof drainage related approaches such as green roofs and rainwater harvesting. Practical application: Over the past few years there have been many changes in how roof drainage systems are specified and designed. On large buildings, technologies such as ‘siphonic roof drainage’ are now commonplace and there is an ever increasing demand for ‘green roofs’ to be specified due to their potential to ‘green’ developments. Based on ongoing research, this paper details how these different types of roof drainage solutions can be efficiently designed and what levels of performance can be expected.
{"title":"Recent and future advances in roof drainage design and performance","authors":"S. Arthur, G. Wright","doi":"10.1191/0143624405bt127tn","DOIUrl":"https://doi.org/10.1191/0143624405bt127tn","url":null,"abstract":"The past 10 years have witnessed significant changes in the way roof drainage systems are understood and designed. In particular, there has been a stepchange in the confidence with which siphonic roof drainage systems may be specified and expected to perform. These changes have occurred whilst urban drainage design in general has been revolutionized by wider acceptance of Sustainable Urban Drainage Systems and greater public concern regarding pluvial flooding within the context of climate change. This text considers, in detail, both how roof drainage systems are designed and how they should be expected to perform. Particular attention is drawn to weaknesses in accepted design methods. Consideration is also given to ‘innovative’ roof drainage related approaches such as green roofs and rainwater harvesting. Practical application: Over the past few years there have been many changes in how roof drainage systems are specified and designed. On large buildings, technologies such as ‘siphonic roof drainage’ are now commonplace and there is an ever increasing demand for ‘green roofs’ to be specified due to their potential to ‘green’ developments. Based on ongoing research, this paper details how these different types of roof drainage solutions can be efficiently designed and what levels of performance can be expected.","PeriodicalId":272488,"journal":{"name":"Building Services Engineering Research and Technology","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121013514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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