建筑类外文翻译环境变化影响下的建筑学

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1、Architecture in a Climate of ChangePage52-Page62Low energy techniques for housingIt would appear that,for the industrialised countries,the best chance of rescue lies with the built environment because buildings in use or in the course of erection are the biggest single indirect source of carbon emis

2、sions generated by burning fossil fuels,accounting for over 50 per cent of total emissions.If you add the transport costs generated by buildings the UK government estimate is 75 per cent.It is the built environment which is the sector that can most easily accommodate fairly rapid change without pain

3、.In fact,upgrading buildings, especially the lower end of the housing stock,creates a cluster of interlocking virtuous circles.Construction systems Having considered the challenge presented by global warming and the opportunities to generate fossil-free energy,it is now time to consider how the dema

4、nd side of the energy equation can respond to that challenge.The built environment is the greatest sectoral consumer of energy and,within that sector,housing is in pole position accounting for 28 per cent of all UK carbon dioxide (CO2) emissions.In the UK housing has traditionally been of masonry an

5、d since the early 1920s this has largely been of cavity construction.The purpose was to ensure that a saturated external leaf would have no physical contact with the inner leaf apart from wall ties and that water would be discharged through weep holes at the damp-proof course level.Since the introdu

6、ction of thermal regulations,initially deemed necessary to conserve energy rather than the planet,it has been common practice to introduce insulation into the cavity.For a long time it was mandatory to preserve a space within the cavity and a long rearguard battle was fought by the traditionalists t

7、o preserve thissacred space.Defeat was finally conceded when some extensive research by the Building Research Establishment found that there was no greater risk of damp penetration with filled cavities and in fact damp through condensation was reduced.Solid masonry walls with external insulation are

8、 common practice in continental Europe and are beginning to make an appearance in the UK.In Cornwall the Penwith Housing Association has built apartments of this construction on the sea front, perhaps the most challenging of situations. The advantages of masonry construction are: It is a tried and t

9、ested technology familiar to house building companies of all sizes. It is durable and generally risk free as regards catastrophic failurethough not entirely.A few years ago the entire outer leaf of a university building in Plymouth collapsed due to the fact that the wall ties had corroded. Exposed b

10、rickwork is a low maintenance system; maintenance demands rise considerably if it receives a rendered finish. From the energy efficiency point of view,masonry homes have a relatively high thermal mass which is considerably improved if there are high density masonry internal walls and concrete floors

11、.Framed constructionVolume house builders are increasingly resorting to timber-framed construction with a brick outer skin,making them appear identical to full masonry construction.The attraction is the speed of erection especially when elements are fabricated off site. However,there is an unfortuna

12、te history behind this system due to shortcomings in quality control.This can apply to timber which has not been adequately cured or seasoned.Framed buildings need to have a vapour barrier to walls as well as roofs. With timber framing it is difficult to avoid piercing the barrier.There can also be

13、problems achieving internal fixings.For the purist,the ultimate criticism is that it is illogical to have a framed building clad in masonry when it cries out for a panel,boarded,slate or tile hung external finish.Pressed steel frames for homes are now being vigorously promoted by the steel industry.

14、The selling point is again speed of erection but with the added benefit of a guaranteed quality in terms of strength and durability of the material.From the energy point of view,framed buildings can accommodate high levels of insulation but have relatively poor thermal mass unless this is provided b

15、y floors and internal walls.Innovative techniquesPermanent Insulation Formwork Systems (PIFS) are beginning to make an appearance in Britain.The principle behind PIFS is the use of precision moulded interlocking hollow blocks made from an insulation material,usually expanded polystyrene.They can be

16、rapidly assembled on site and then filled with pump grade concrete.When the concrete has set the result is a highly insulated wall ready for the installation of services and internal and exterior finishes.They can achieve a U-value as low as 0.11 W/m2K.Above three storeys the addition of steel reinf

17、orcement is necessary. The advantages of this system are: Design flexibility; almost any plan shape is possible. Ease and speed of erection;skill requirements are modest which is why it has proved popular with the self-build sector.Experienced erectors can achieve 5 m2 per man hour for erection and

18、placement of concrete. The finished product has high structural strength together with considerable thermal mass and high insulation value.Solar designPassive solar designSince the sun drives every aspect of the climate it is logical to describe the techniques adopted in buildings to take advantage

19、of this fact assolar design. The most basic response is referred to aspassive solar design.In this case buildings are designed to take full advantage of solar gain without any intermediate operations. Access to solar radiation is determined by a number of conditions: the suns position relative to th

20、e principal facades of the building(solar altitude and azimuth); site orientation and slope; existing obstructions on the site; potential for overshadowing from obstructions outside the site boundary.One of the methods by which solar access can be evaluated is the use of some form of sun chart.Most

21、often used is the stereographic sun chart in which a series of radiating lines and concentric circles allow the position of nearby obstructions to insolation,such as other buildings,to be plotted.On the same chart a series of sun path trajectories are also drawn(usually one arc for the 21st day of e

22、ach month); also marked are the times of the day.The intersection of the obstructionsoutlines and the solar trajectories indicate times of transition between sunlight and shade. Normally a different chart is constructed for use at different latitudes (at about two degree intervals).Sunlight and shad

23、e patterns cast by the proposed building itself should also be considered.Graphical and computer prediction techniques may be employed as well as techniques such as the testing of physical models with a heliodon. Computer modelling of shadows cast by the sun from any position is offered by Integrate

24、d Environmental Solutions (IES) with itsSuncastprogram.This is a user-friendly program which should be well within normal undergraduate competence. The spacing between buildings is important if overshading is to be avoided during winter months when the benefit of solar heat gain reaches its peak.On

25、sloping sites there is a critical relationship between the angle of slope and the level of overshading.For example, if overshading is to be avoided at a latitude of 50N,rows of houses on a 10 north-facing slope must be more than twice as far apart than on10 south-facing slope. Trees can obviously ob

26、struct sunlight.However,if they are deciduous,they perform the dual function of permitting solar penetration during the winter whilst providing a degree of shading in the summer.Again spacing between trees and buildings is critical. Passive solar design can be divided into three broad categories: di

27、rect gain; indirect gain; attached sunspace or conservatory.Each of the three categories relies in a different way on thegreenhouse effect as a means of absorbing and retaining heat.The greenhouse effect in buildings is that process which is mimicked by global environmental warming.In buildings,the

28、incident solar radiation is transmitted by facade glazing to the interior where it is absorbed by the internal surfaces causing warming.However,re-emission of heat back through the glazing is blocked by the fact that the radiation is of a much longerwavelength than the incoming radiation.This is bec

29、ause the re-emission is from surfaces at a much lower temperature and the glazing reflects back such radiation to the interior.Direct gainDirect gain is the design technique in which one attempts to concentrate the majority of the buildings glazing on the sun-facing facade.Solar radiation is admitte

30、d directly into the space concerned.Two examples 30 years apart are the authors house in Sheffield,designed in 1967 and the Hockerton Project of 1998 by Robert and Brenda Vale.The main design characteristics are: Apertures through which sunlight is admitted should be on the solar side of the buildin

31、g, within about 30 of south for the northern hemisphere. Windows facing west may pose a summer overheating risk. Windows should be at least double glazed with low emissivity glass (Low E) as now required by the UK Building Regulations. The main occupied living spaces should be located on the solar s

32、ide of the building. The floor should be of a high thermal mass to absorb the heat and provide thermal inertia,which reduces temperature fluctuations inside the building. As regards the benefits of thermal mass,for the normal daily cycle of heat absorption and emission,it is only about the first 100

33、 mm of thickness which is involved in the storage process.Thickness greater than this provides marginal improvements in performance but can be useful in some longer-term storage options. In the case of solid floors,insulation should be beneath the slab. A vapour barrier should always be on the warm

34、side of any insulation. Thick carpets should be avoided over the main sunlit and heatabsorbing portion of the floor if it serves as a thermal store.However,with suspended timber floors a carpet is an advantage in excluding draughts from a ventilated underfloor zone.During the day and into the evenin

35、g the warmed floor should slowly release its heat, and the time period over which it happens makes it a very suitable match to domestic circumstances when the main demand for heat is in the early evening. As far as the glazing is concerned,the following features are recommended: Use of external shut

36、ters and/or internal insulating panels might be considered to reduce night-time heat loss. To reduce the potential of overheating in the summer,shading may be provided by designing deep eaves or external louvres. Internal blinds are the most common technique but have the disadvantage of absorbing ra

37、diant heat thus adding to the internal temperature. Heat reflecting or absorbing glass may be used to limit overheating.The downside is that it also reduces heat gain at times of the year when it is beneficial. Light shelves can help reduce summer overheating whilst improving daylight distribution.D

38、irect gain is also possible through the glazing located between the building interior and attached sunspace or conservatory;it also takes place through upper level windows of clerestory designs.In each of these cases some consideration is required concerning the nature and position of the absorbing

39、surfaces. In the UK climate and latitude as a general rule of thumb room depth should not be more than two and a half times the window head height and the glazing area should be between about 25 and 35 per cent of the floor area.Indirect gainIn this form of design a heat absorbing element is inserte

40、d between the incident solar radiation and the space to be heated;thus the heat is transferred in an indirect way.This often consists of a wall placed behind glazing facing towards the sun,and this thermal storage wall controls the flow of heat into the building.The main elements High thermal mass e

41、lement positioned between sun and internal spaces,the heat absorbed slowly conducts across the wall and is liberated to the interior some time later. Materials and thickness of the wall are chosen to modify the heat flow.In homes the flow can be delayed so that it arrives in the evening matched to o

42、ccupancy periods. Typical thicknesses of the thermal wall are 2030 cm. Glazing on the outer side of the thermal wall is used to provide some insulation against heat loss and help retain the solar gain by making use of the greenhouse effect. The area of the thermal storage wall element should be abou

43、t 1520 per cent of the floor area of the space into which it emits heat. In order to derive more immediate heat benefit,air can be circulated from the building through the air gap between wall and glazing and back into the room.In this modified form this element is usually referred to as a Trombe wa

44、ll. Heat reflecting blinds should be inserted between the glazing and the thermal wall to limit heat build-up in summer. In countries which receive inconsistent levels of solar radiation throughout the day because of climatic factors (such as in the UK),the option to circulate air is likely to be of

45、 greater benefit than awaiting its arrival after passage through the thermal storage wall.At times of excess heat gain the system can provide alternative benefits with the air circulation vented directly to the exterior carrying away its heat,at the same time drawing in outside air to the building f

46、rom cooler external spaces.Indirect gain options are often viewed as being the least aesthetically pleasing of the passive solar options,partly because of the restrictions on position and view out from remaining windows,and partly as a result of the implied dark surface finishes of the absorbing sur

47、faces.As a result,this category of the three prime solar design technologies is not as widely used as its efficiency and effectiveness would suggest.Attached sunspace/conservatoryThis has become a popular feature in both new housing and as an addition to existing homes.It can function as an extensio

48、n of living space,a solar heat store,a preheater for ventilation air or simply an adjunct greenhouse for plants.On balance it is considered that conservatories are a net contributor to global warming since they are often heated.Ideally the sunspace should be capable of being isolated from the main b

49、uilding to reduce heat loss in winter and excessive gain in summer.The area of glazing in the sunspace should be 2030 per cent of the area of the room to which it is attached.The most adventurous sunspace so far encountered is in the Hockerton housing development which will feature later. Ideally th

50、e summer heat gain should be used to charge a seasonal thermal storage element to provide background warmth in winter.At the very least,air flow paths between the conservatory and the main building should be carefully controlled.Active solar thermal systemsA distinction must be drawn between passive

51、 means of utilising the thermal heat of the sun, discussed earlier,and those of a moreactivenature Active systems take solar gain a step further than passive solar.They convert direct solar radiation into another form of energy.Solar collectors preheat water using a closed circuit calorifier.The eme

52、rgence of Legionella has highlighted the need to store hot water at a temperature above 60C which means that for most of the year in temperate climes active solar heating must be supplemented by some form of heating. Active systems are able to deliver high quality energy.However,a penalty is incurre

53、d since energy is required to control and operate the system known as the parasitic energy requirement.A further distinction is the difference between systems using the thermal heat of the sun,and systems,such as photovoltaic cells, which convert solar energy directly into electrical power. For sola

54、r energy to realise its full potential it needs to be installed on a district basis and coupled with seasonal storage.One of the largest projects is at Friedrichshafen.The heat from 5600 m2 of solar collectors on the roofs of eight housing blocks containing 570 apartments is transported to a central

55、 heating unit or substation.It is then distributed to the apartments as required.The heated living area amounts to 39 500 m2.Surplus summer heat is directed to the seasonal heat store which,in this case, is of the hot water variety capable of storing 12 000 m3.The scale of this storage facility is i

56、ndicated by Figure 5.9.The heat delivery of the system amounts to 1915 MWh/year and the solar fraction is 47 per cent.The month by month ratio between solar and fossil-based energy indicates that from April to November inclusive,solar energy accounts for almost total demand,being principally domesti

57、c hot water. In places with high average temperatures and generous sunlight,active solar has considerable potential not just for heating water but also for electricity generation.This has particular relevance to less and least developed countries.环境变化影响下的建筑学房屋设计中的低能耗技术显而易见，在工业化国家，最好的营救机会依赖于建筑环境，因为不论

58、是在使用的建筑或者是在建设的建筑，都是最大的、单一的、间接地由化石燃料的燃烧所引起的碳排放的源头，而这些站了所有排放的50%。如果你加上为建造这些建筑在运输上所产生的碳排放，英国政府估计这个数字会上升到75%。也就是在建成环境这个领域里，能够简单的容纳如此快速的改变却不产生负面效果。事实上，升级建筑，特别是那些较老较旧的房子，将会营造一个连锁的良性循环。施工系统考虑到现在由全球性变暖以及非化石燃料使用机会所带来的的挑战。现在就是最好的时机去解决能量方程式一边的需求如何作用到这一挑战。建成环境是所有能耗中最大的消费者，在这里，住宅又以全英国28%的二氧化碳排放居于杆位。 在英国，一直就有用石头建

59、设住宅的出传统，并且从十九世纪二十年代早期开始，这一习惯得到了广泛的应用。这是为了使一个极湿的外表面能不至于和其内表面存在物理上的连接，这样，墙的联系被分开了，水也能够通过防水通排向外面。自从把热源控制引进来以后，最初人们认为的保护能源比保护星球更重要的理念，已经被广泛的在建筑洞口绝热材料的使用上。在一段很长的时间里，保护建筑的洞口是被强制命令的，并且一场由传统主义者发起的保护“圣所”的战争也已经持续了很久。失败最终被承认，通过BRE的大量研究我们发现，填满建筑的洞口并不会提高潮气穿透建筑的奉献，事实上，通过洞口的潮气反而减少了。带有外部绝热材料的砌体墙面被广泛的在欧洲大陆实践，在英国，他们甚

60、至作为外立面的装饰而使用。在康沃尔郡，PHA在面朝大海的地方用这种方法建了一栋住宅，肯能这就是最具挑战的条件了。砌体建筑的优势有：对于任何建筑公司而言，他都是一个熟悉并经得住考验的技术。他是一个使用寿命长，并且通常情况下不会产生毁灭性灾难的建筑形式，尽管他还不是很完善。几年前，普利茅斯一所大学建筑的整个屋顶突然坍塌，经调查，墙的连接部分被腐蚀是这一事故的缘由。裸露的砖石结构是一种低维护费的系统，如果奏效的话，维护费还会上升很大一部分。从能效的角度考虑，如果其有高密度的砌体内墙和混凝土楼板，砌体住宅本身较高的比热还将有一个很大的提升。框架建筑大量住宅的建筑者开始热衷于采用有砖石外墙的木构架建筑，

61、这使得他们他们看起来和砌体建筑一样。他的吸引力在于如果基础在空闲的地区进行建设，建筑速度将会非常的快。然而这一系统仍然有一个不幸的历史背景，因为在质量控制方面它还存在着很多的缺点。这些突出的表现在那些不是很牢固或者不成熟的木材上。框架建筑和屋顶一样需要防潮层。加上木结构以后他将很难避免潮气的渗透，在内部固定方面也仍然存在着很多问题。对于那些纯粹论者，最大的指责在于当框架建筑迫切的需要一个以面板，屋面，石板或瓦片悬挂在外部结束的时候，这在某种程度上是不合逻辑的。现在，钢铁工业大大促进了为家庭而制的压制钢框架的应用。伴随新建筑材料在强度和耐久能力上的良好保证，即使施工速度很快，还是很有卖点的。从能

62、源角度看，框架建筑能够提供较高等级的隔绝效果，但是框架建筑有一个相对较低的比热，除非其由地板和内墙提供。创新的技术在英国，PIFS正在为新的技术努力。他们的原则底线是由绝热材料制作的精确模数化得榫卯结构的使用，通常这些是膨胀聚苯乙烯。因为他们可以被快速装配，并填充上加气水泥。当混凝土结构完成，将会变成一个更高效的绝热墙，无论是在内部还是外部的安装服务上。这样，他将以小于0.11W/K的成绩得到一个U级评价。超过三层的建筑，钢筋的增加还是必要的。这一系统的优势在于：设计的灵活性：几乎所有的形状都是可以的。简单且快速的建筑时间：适度的技术要求使得他在自家建筑中非常流行，经验丰富的建筑工人可以以每小

63、时5平方米的速度用混凝土进行建设。最终的成果具有较高的建筑强度并且兼有比较不错的比热和隔热等级。日光设计积极的日光设计自从太阳驱动每个季节的变化以来，人们利用“日光设计”这一优势在建筑上就很合乎逻辑了。最基本的答复就是像“积极地日光设计”一样。因此，现在的建筑设计都会充分利用太阳能而非间接地通过其他方式。通过的太阳辐射决定于一系列的因素：太阳对于建筑主立面的位置（太阳方位角和高度角）基地的定位和坡度基地现存的障碍物基地外潜在的会遮挡阳光的物体太阳辐射的一种评价方式是某种形式的太阳图标，最常使用的是立体太阳图表，在这种图标里，一系列的射线和许多同心圆使得我们能够得到遮挡物的日照分析。就像其他建筑

64、一样，用来标绘。在相同的图志上，一系列的太阳光路径被绘制（通常情况下是每个月的第21天）；并且同样也会把那天的时间标识上。太阳光照射到遮挡物的外轮廓所形成阴影的交叉口就是阳光和阴影的分割部分。通常情况下不同的纬度会有不同的图志（一般在两个纬度等级之内）。建筑自身对光线和阴影的影响也要被考虑进来，图解的、计算机预测技术可能受制于像在同一个日影仪下的物理模型测试的技术。IES的“阳光投影”程序可以用电脑模拟从任何一个角度投射的太阳光和影。这是一个对于拥有一般技能的大学生都很容易掌握的程序。两个建筑物之间的距离是很重要的，这样可以避免在冬季获得阳光最好的时候得不到足够多的阳光。再有坡度的地块内，坡底

65、的坡度和遮挡的等级之间存在一个决定性的关系。比如说，如果要在北纬50的地方避免阳光被遮挡，北倾10排列的建筑群之间的距离要比南倾10的建筑群的间距多一倍。大树很明显会遮挡阳光。但是如果他们是落叶植物，他们将扮演两重角色。在冬天，他可以是阳光通过他们进行照射；在夏天，他又能提供相当数量的阴影。积极的阳光设计可以被分为三大类：直接获得阳光间接获得阳光附加日光间或者温室这三种方式中的任何一种都是从不同角度利用“温室效应”，而这正是一种吸收和保留温度的方法。温室效应在建筑上的应用是模仿全有气候变暖的过程，在建筑上，偶尔的太阳辐射是通过建筑主立面的窗户透射进来的，房屋内表面吸收以后使得房间的温度得到提高。然而，二次辐射所产生的热量却被玻璃窗阻隔在内，因为这一波长要远比辐射进来的长。二次辐射的辐射源是内部墙面，他的温度要比外面的温度低很多，玻璃窗也正好可以将其反射到内部。直接获得阳光直接获得的建筑技术是集中绝大多数的玻璃