The effects of roof albedo modification on cooling loads of scale model residences in Tucson,Arizona

Data supporting reductions in cooling load and related demand for electric power possible from increasing building surface albedo are limited. Electrical use of wall-mounted air conditioners, roof temperatures, and related environmental factors were monitored during the summer of 1990 on three initially identical 1/4-scale model buildings situated in rock mulch landscapes in Tucson, Arizona. Model thermodynamic properties were scaled to approximate thermodynamic similarity with full-size buildings. With ceiling insulation of R value 5.28 m² K W⁻¹ (R-30) installed, increasing roof albedo of the gray composition shingles (0.30 albedo, 0.94 emissivity) by painting one roof silver and another white (0.49 and 0.75 albedos, 0.70 and 0.98 emissivities, respectively) reduced daily total and hourly peak electrical use for air conditioning approximately 5% for the house with white-colored roof compared to either gray or silver-colored roofs. Larger differences were found without ceiling insulation, with daily total and peak hourly demand for houses with white compared to dark brown roofing (0.9 albedo, 0.98 emissivity) reduced 28 and 18%, respectively. Computer simulations of daily total energy use confirmed comparable savings for similar full-sized buildings. White roofs were 20 to 30°C cooler than either silver or dark-colored roofs on hot, sunny days, indicating that expected cooling due to an increase in albedo may not be realized if it is accompanied by a decrease in emissivity. Light colored roofs, by maintaining cooler attic temperatures, may provide savings in addition to those presented here by reducing heat gain to air distribution systems located in the attic space.     

城市模型反射率测量方法与运用

介绍了一种测试城市模型反射率的试验方法。制作10个条形和十字形的城市模型进行测试,观测路面不同反射率对城市反射率的影响,并将实测模型反射率与ASTM E1918-06规范计算结果进行对比。研究发现:瞬时太阳辐射强度变化值在规范允许范围内,模型计算的反射率与ASTM E1918-06测量值的误差在0~0.1之间。当峡谷纵横比(建筑物高度与路面宽度之比)为1.0时,路面反射率从0.15提高到0.65,城市峡谷反射率增幅在0~0.30之间;提高路面反射率并不能有效提高城市峡谷反射率,尤其是纵横比较大的深峡谷。城市峡谷中的多重反射抑制城市反射率的提高。同时,反射路面将给行人增加额外的辐射通量,可能带来热不适感和眩光刺眼等问题。因此,应谨慎看待反射路面作为一个缓解城市热岛效应策略。     

Design strategy for low-energy ventilation and cooling within an urban heat island

Natural ventilation is a proven strategy for maintaining thermal comfort in non-domestic buildings in the UK. The energy consumption and thus the carbon dioxide emissions that contribute to global warming are lower than in conventional air-conditioned buildings. However, the ambient temperatures in the UK have risen over the last decade and new climatic data for use in the design of naturally ventilated buildings has been published. Using these data and dynamic thermal modelling, it is shown that passive stack ventilation alone was unlikely to maintain summertime comfort in a proposed University College London building within an urban heat island. The stack ventilation strategy was evolved by the introduction of passive downdraught cooling. This low-energy technique enables cooled air to be distributed throughout the building without mechanical assistance. The underlying principles of the technique were explored using physical models and the anticipated performance predicted using thermal modelling. The architectural integration is illustrated and the control strategy described. The resulting building is believed to be the first large-scale application of the passive downdraught cooling technique; construction began in late 2003.     

Design strategy for low-energy ventilation and cooling within an urban heat island

Natural ventilation is a proven strategy for maintaining thermal comfort in non-domestic buildings in the UK. The energy consumption and thus the carbon dioxide emissions that contribute to global warming are lower than in conventional air-conditioned buildings. However, the ambient temperatures in the UK have risen over the last decade and new climatic data for use in the design of naturally ventilated buildings has been published. Using these data and dynamic thermal modelling, it is shown that passive stack ventilation alone was unlikely to maintain summertime comfort in a proposed University College London building within an urban heat island. The stack ventilation strategy was evolved by the introduction of passive downdraught cooling. This low-energy technique enables cooled air to be distributed throughout the building without mechanical assistance. The underlying principles of the technique were explored using physical models and the anticipated performance predicted using thermal modelling. The architectural integration is illustrated and the control strategy described. The resulting building is believed to be the first large-scale application of the passive downdraught cooling technique; construction began in late 2003.     

Characteristics of heating and cooling loads in apartments

The energy required to heat and to cool an apartment varies according to the aspect and situations of the rooms in the apartment, the mode of air-conditioning (all day or intermittent) and the geographical location of the building it is situated in. A year-round computer simulation has been carried out using hourly meteorological information throughout 1975 in each of seven districts — Sapporo, Akita, Tokyo, Nagoya, Osaka, Kagoshima and Naha. The capacity requirements of the equipment, and the total energy requirement for year-round air-conditioning for a room situated in the centre of the south side, middle floor of a building in Tokyo was calculated as the planning guide, varying the situations and directions. The research continued with the study of air-conditioning load ratios for each district, measured by the degree-day and calorie-day index, so that year-round air-conditioning loads in other districts could be easily obtained.     

反射路面对城市峡谷反射率的影响

太阳辐射在城市峡谷内形成多重反射,加剧城市热岛效应。峡谷太阳辐射吸收量与城市结构、墙体和路面反射率及时间显著相关。建立城市峡谷反射率数值模型,评估提高路面反射率能否有效提高城市峡谷反射率,并探讨反射路面对邻近建筑墙体的反射与散射辐射的影响。通过现场观测数据验证数值模型的可靠性。研究结果表明:建筑物高度与路面宽度之比(纵横比)是城市峡谷反射率最关键的影响因素,当峡谷纵横比1.0时,路面反射作用较为明显;而且,相对于冬季,夏季时峡谷内反射路面能向邻近建筑物反射更多的额外散射辐射,而峡谷走向对额外散射辐射的影响较小。当峡谷纵横比1.0时,建议采用反射路面缓解城市热岛。     

热负荷与供热工程设备的估算

1概述 随着改革开放不断深入,城市建设迅速发展,近几年各地房屋开发大量兴起,作为开发商意在较短时间内获得较好经济效益,在工程筹建期间除对土建工程进行测算外,还要对其配套工程进行足够的估算.一个工程项目其配套工程包括,供水、供电、供热与供煤气等,其中供热工程是一个重要组成部分.合理地确定供热工程的规模,不仅可以节约基建投资、缩短建设时间、节约能源、保护环境、提供良好的外部环境,同时还可少走弯路,减少不必要的损失.本文就供热工程的设备,热源→管网→散热器的概略估算提出如下几点看法,可供参考.     

Ambivalent landscapes—wilderness in the urban interstices

This paper explores the origins and development of ambivalent responses to particular contemporary urban landscapes in historical ideas about human relationships with nature and wilderness, and suggests that post-modern wilderness may be found in the urban interstices: in woodland, abandoned allotments, river corridors, derelict or brownfield sites and especially areas in which the spontaneous growth of vegetation through natural succession suggests that nature is in control. We propose that these interstitial wilderness landscapes have numerous important functions as well as being rich repositories of meaning with implications both for theorizing nature-human relationships and for urban landscape planning and design.     

谈住宅户间传热负荷及不同围护结构传热负荷

以目前较为常见的加气混凝土填充墙外保温的框架剪力墙高层住宅为对象,分析了住宅标准层和顶层的典型户型采用分户热计量并进行分室调节时的室温、热负荷及户间传热量的逐时变化情况,以得出一些有意义的结论。     

Incorporation of latent loads into the cooling degree days concept

The cooling degree days concept is a tool to estimate and analyze weather related energy consumption in buildings, i.e. the cooling system electric energy consumption. The main problem with applying this method is that it disregards latent cooling loads. This paper deals with an approach for monitoring electric energy consumption due to cooling in buildings based on cooling degree days, which allows an estimation of latent loads. In addition to applying methods for determining base temperature to base humidity, a new technique is introduced, which is based on a significance test of the enthalpy latent days partial regression coefficient. Analogous to the performance line concept, the influence of latent loads can be presented in the form of a “performance surface” graph. The performance surface is a plot of electric energy consumption as a function of cooling degree days and latent enthalpy days. The above methods are tested on data sets consisting of electric energy consumption data obtained from two buildings and hourly meteorological data.     

长江流域住宅夏季通风降温方式探讨

认为全天持续自然通风对于长江流域住宅夏季降温效果很差，不应继续采用。推荐白天限制通风，夜间强化通风的间歇机械通风方式。实测结果表明，这种方式可取得相当满意的降温效果，而３７０砖墙住宅又优于２４０砖墙住宅。提出了预测间歇通风效果的回归方程。     

Pollution loads in urban runoff and sanitary wastewater

While more attention has been paid in recent years to urban point source pollution control through the establishment of wastewater treatment plants in many developing countries, no considerable planning nor any serious measures have been taken to control urban non-point source pollution (urban stormwater runoff). The present study is a screening analysis to investigate the pollution loads in urban runoff compared to point source loads as a first prerequisite for planning and management of receiving water quality. To compare pollutant loads from point and non-point urban sources, the pollutant load is expressed as the weight of pollutant per hectare area per year (kg/ha.year). Unit loads were estimated in stormwater runoff, raw sanitary wastewater and secondary treatment effluents in Isfahan, Iran. Results indicate that the annual pollution load in urban runoff is lower than the annual pollution load in sanitary wastewater in areas with low precipitation but it is higher in areas with high precipitation. Two options, namely, advanced treatment (in lieu of secondary treatment) of sanitary wastewater and urban runoff quality control systems (such as detention ponds) were investigated as controlling systems for pollution discharges into receiving waters. The results revealed that for Isfahan, as a low precipitation urban area, advanced treatment is a more suitable option, but for high precipitation urban areas, urban surface runoff quality control installations were more effective for suspended solids and oxygen-demanding matter controls, and that advanced treatment is the more effective option for nutrient control.     

浅谈城市热岛

对城市热岛现象的产生原因以及城市热岛对人类生存环境以及人体健康的危害进行了初步的探讨,而后对于城市热岛现象,提出了几种可行的改善措施,从而缓解城市热岛效应.     

Low cost urban housing — thermal efficiency

Structural Engineer, Mrs Rahooja, is a Principal Scientific Officer with the National Building Research Institute, Karachi and with her colleages, Mr Muzaffar Hasan and Mr Tanveer Saleem, describes their study into the thermal efficiency of low cost housing in the warm, humid climate of Karachi, with mean outdoor summer temperatures of 35°C.     

Study on the influence of albedo on building heat environment in a year-round

The research of energy saving is one of the highlights of buildings environment. According to the albedo change of the wall-facing materials of urban buildings, two building models were constructed, of which the internal and external microclimate parameters were measured under certain meteorological conditions in different seasons. The experimental results show that the decrease of indoor air temperature was up to 4.67 °C with the average diurnal temperature decrease up to 3.53 °C in summer, and the increase was up to 2.81 °C in winter when the albedo changed from 0.21 to 0.86. Moreover, Laplace integral transform method was used to analyze building energy saving. The results indicate that the wall-facing materials with high albedo have the function of heat-protection and heat-insulation and could reduce 150.3 W per day of the buildings’ cooling load in summer and 69.5 W per day of heating load in winter. The research results confirm that employing high albedo coatings on the building exterior wall is an active and effective approach to improve the urban buildings’ micro-heat environment.     

智能被动冷却和热回收系统

Monodraught公司花了30多年的时间来设计自然通风设备和日光解决方案,以提升建筑内的环境质量、减少能源消耗和碳排放量。如今该公司对外宣称新研究已经取得了进一步的发展,这项研究成果使用极少的能源,并拥有智能的被动制冷和热回收系统。