correspondence文献

Lessor (hereinafter referred to as Party A) Lessee (hereinafter referred to as Party B)Company Name: Company Name:Company Address: Address:Legal representative: Legal representative:Under the "Contract Law" and the relevant provisions of the Party and Party B for the specific rights and obligations, both voluntary and equal basis, under the principle of equal compensation through full consultations, specific legislation in this The contents of the first leaseParty A will be located in urban areas leased to Party B N Party on the rental housing has a legitimate property Second, a lease to Party B of the housing construction area of square meters floor area in square Party B agreed to the leased building for business use, the extent of the business license to Party B shall 4, Party A Party B to provide the room are: fire facilities and equipment for power The equipment operation and maintenance costs, included in the rental, Party B will not be The second term of the leaseFive-year lease, until years from the date of years Article rent and other costs6, the effective annual rent for a total contract yuan (RMB)7, each lease year on a monthly 8, the actual use of electricity by the daily number of (measured) and, on the 10th turn in each month on electricity (Party Agency to produce electricity fees invoice) other expenses, mutual agreement added to this Article IV rights and obligations of both parties9, Party(A) Party A shall ensure that rental housing and be in good condition and can be used normally, and is responsible for annual inspections and routine maintenance, repair; who come across government departments seeking to transform the facilities needed on, all costs borne by Party (Ii) leased by Party B or renovation of housing renovation programs to monitor and review and timely (3) is responsible for coordinating the relationship between the various departments in the region, and Party B to provide a valid business license and related procedures that (D) Party A ensure that the original interior wires, cables to meet the B normal business use, and regular checks of their integrity (B own excluded), found that problems should be promptly informed of the P As the supply line issues to the economic losses caused by Party B, Party B should be given full (E) During the contract period, Party A shall not be introduced again similar (jewelry) Such as breach of contract should compensate Party B RMB economic damages, and clear the (Vi) Party A shall ensure that rental housing meet industry requirements for fire safety installations, fire jurisdiction to provide Party B issued by the department of electricity, fire inspection certificate (G) the equipment, facilities problems Party shall promptly repair or replace, if not timely implementation of the Party, Party B is entitled on behalf of repair or replacement costs (invoice) deducted from the 10, B(A) national laws, regulations, policies, operating within the permitted and (B) of the contract period, on the rental housing and facilities have the legal right to (C) of the contents of the contract to pay rent and other Article V and the time of payment11, signed a contract to pay Party B RMB Party for the deposit, within five days after the formal admission to the first month's rent RMB 12, B from the second payment, each time this month, five days before 13, Party B shall pay the fees can use bank transfer, check, money order or Article VI housing renovation or reconstruction14, B, such as the need for the rental housing renovation or reconstruction, it must first obtain the written consent of Party A, Party B shall own the costs of Termination of the contract, cancel the lease relationship, B, or transformation and renovation of facilities housing all owned by Party all (except the mobile facilities)Article renewal15, after the expiration of this contract, Party B has the 16, B For renewal, the lease should be made before the expiry of two months to the Party, and sign a new lease Article VIII Other17, Party A and Party B changes the legal representative of any party, corporate relocation, merger, does not affect the continued performance of this Changes, the party that merged to become executor of this contract, of course, and assume the contents of this contract the rights and 18, need for a provision of this contract change, it must be determined in writing, the two sides entered into a supplemental agreement, received a letter written reply within ten days of parties in each other, not reply within ten days are deemed to agree, finally reaching a supplementary 19, the two sides go through their property insurance, and do not bear the risk of any form of 20, B business hours may be adjusted according to customer Article default21, A and B signed the rental Party B has paid the deposit, the employer does not schedule well in full, the transfer of rental housing and equipment, Party B, Party A breach of contract Party day 1% of annual rent payments delayed penalty to Party B, while Party B shall be entitled to recover the delay of the deposit, until fully recovered terminate the 22, the validity of the contract without the consent Party B, Party A, the increase in rent, B the right to refuse to pay the excess 23, any unilateral move to cancel, terminate contracts, months in advance notice to the 24, Party A has not paid any amount due to Party B is breach of contract, each overdue day, in addition to pay the amount owed, the daily payment of the arrears to the Party 1%

A standard form contract (sometimes referred to as an adhesion contract or boilerplate contract) is a contract between two parties that does not allow for negotiation, take it or leave It is often a contract that is entered into between unequal bargaining partners, such as when an individual is given a contract by the salesperson of a multinational The customer in no position to negotiate the standard terms of such contracts and the company's representative often does not have the autonomy to do While adhesion contracts, in and of themselves, are not illegal per se, there exists a very real possibility for There is some debate on a theoretical level whether, and to what extent, courts should enforce standard form On one hand, they undeniably fulfill an important efficiency role in Standard form contracting reduces transaction costs substantially by precluding the need for buyers and sellers of goods and services to negotiate the many details of a sale contract each time the product is On the other hand, there is the potential for inefficient, and even unjust, terms to be accepted by those signing these Such terms might be seen as unjust if they allow the seller to avoid all liability or unilaterally modify terms or terminate the These terms often come in the form of, but are not limited to, forum selection clauses and mandatory arbitration clauses, which can limit or foreclose a party's access to the courts; and also liquidated damages clauses, which set a limit to the amount that can be recovered or require a party to pay a specific They might be inefficient if they place the risk of a negative outcome, such as defective manufacturing, on the buyer who is not in the best position to take There are a number of reasons why such terms might be acceptedStandard form contracts are rarely readLengthy boilerplate terms are often in fine print and written in complicated legal language which often seems The prospect of a buyer finding any useful information from reading such terms is correspondingly Even if such information is discovered, the consumer is in no position to bargain as the contract is presented on a “take it or leave it” Coupled with the often large amount of time needed to read the terms, the expected payoff from reading the contract is low and few people would be expected to read Sometimes a standard form contract may literally be dispensed from a vending machine to drivers sitting in line to enter a parking garage, which means that stopping to read the contract risks provoking road Access to the full terms may be difficult or impossible before acceptanceOften the document being signed is not the full contract; the purchaser is told that the rest of the terms are in another This reduces the likelihood of the terms being read and in some situations, such as software license agreements, can only be read after they have been notionally accepted by purchasing the good and opening the These contracts are typically not enforced, since common law dictates that all terms of a contract must be disclosed before the contract is Boilerplate terms are not salientThe most important terms to purchasers of a good are generally the price and the quality, which are generally understood before the contract of adhesion is Terms relating to events which have very small probabilities of occurring or which refer to particular statutes or legal rules do not seem important to the This further lowers the chance of such terms being read and also means they are likely to be ignored even if they are There may be social pressure to signStandard form contracts are signed at a point when the main details of the transaction have either been negotiated or Social pressure to conclude the bargain at that point may come from a number of The salesperson may imply that the purchaser is being unreasonable if they read or question the terms, saying that they are "just something the lawyers want us to do" or that they are wasting their time reading If the purchaser is at the front of a queue (for example at an airport car rental desk) there is additional pressure to sign Finally, if there has been negotiation over price or particular details, then concessions given by the salesperson may be seen as a gift which socially obliges the purchaser to respond by being co-operative and concluding the Standard form contracts may exploit unequal power relationsIf the good which is being sold using a contract of adhesion is one which is essential or very important for the purchaser to buy (such as a rental property or a needed medical item) then the purchaser might feel they have no choice but to accept the This problem may be mitigated if there are many suppliers of the good who can potentially offer different terms (see below)Some contend that in a competitive market, consumers have the ability to shop around for the supplier who offers them the most favorable terms and are consequently able to avoid However, in the case of credit card contracts, for example, the consumer while having the ability to shop around may still have access to only form contracts with like terms and no opportunity for Also, as noted, many people do not read or understand the terms so there might be very little incentive for a firm to offer favorable conditions as they would gain only a small amount of business from doing Even if this is the case, it is argued by some that only a small percentage of buyers need to actively read standard form contracts for it to be worthwhile for firms to offer better terms if that group is able to influence a larger number of people by affecting the firm’s Another factor which might mitigate the effects of competition on the content of contracts of adhesion is that, in practice, standard form contracts are usually drafted by lawyers instructed to construct them so as to minimize the firm’s liability, not necessarily to implement managers' competitive Sometimes the contracts are written by an industry body and distributed to firms in that industry, increasing homogeneity of the contracts and reducing consumer's ability to shop Common law statusAs a general rule, the common law treats standard form contracts as any other Signature or some other objective manifestation of intent to be legally bound will bind the signor to the contract whether or not they read or understood the The reality of standard form contracting, however, means that many common law jurisdictions have developed special rules with respect to In general, courts will interpret standard form contracts contra proferentem (literally 'against the proffering person') but specific treatment varies between Contracts of adhesionContract of adhesion on timekeeping ticket dispensed by vending machine at parking lot entranceThe concept of the contract of adhesion originated in French civil law, but for example, it did not enter American jurisprudence until the Harvard Law Review published an influential article by Edwin W Patterson in It was subsequently adopted by the majority of American courts, especially after the Supreme Court of California endorsed adhesion analysis in For a contract to be treated as a contract of adhesion, it must be presented on a standard form on a ‘take it or leave it’ basis, and give one party no ability to negotiate because of their unequal bargaining The special scrutiny given to contracts of adhesion can be performed in a number of ways:If the term was outside of the reasonable expectations of the person who did not write the contract, and if the parties were contracting on an unequal basis, then it will not be The reasonable expectation is assessed objectively, looking at the prominence of the term, the purpose of the term and the circumstances surrounding acceptance of the Section 211 of the American Law Institute's Restatement (Second) of Contracts, which has persuasive though non-binding force in courts, provides:Where the other party has reason to believe that the party manifesting such assent would not do so if he knew that the writing contained a particular term, the term is not part of the This is a subjective test focusing on the mind of the seller and has been adopted by only a few state The doctrine of unconscionability is a fact-specific doctrine arising from equitable Unconscionability in standard form contracts usually arises where there is an "absence of meaningful choice on the part of one party due to one-sided contract provisions, together with terms which are so oppressive that no reasonable person would make them and no fair and honest person would accept "

我毕业设计的，虽说语言有点生涩，不过是自己翻译的，应该符合老师的要求。英文是PDF格式的建筑物服务工程设计与技术屋顶排水设计性能的近期与远期优势最近十年见证了屋顶排水系统设计方面的巨大变化，特别的是，虹吸雨水排水系统已经得到逐步改善，并且有可能得到重点应用。发生这些变化的同时，城市排水系统设计已经发生了巨大的变化，因为适用范围更广的可持续发展城市排水系统设计，还有人们对于气候变化带来的洪水泛滥的更多关注。这篇文章的主要内容就是，如何设计屋顶雨水排水系统并使之有良好的运行性能。需要特别注意的是如何改掉已经形成的不良设计习惯，同时还要需要考虑屋顶排水系统的创新，如绿色屋顶和雨水收集系统。实际应用：在过去几年，屋顶雨水排水系统的设计已经发生了巨大的变化。在大型建筑物上，虹吸雨水排水技术已经很常见，还有绿色屋顶由于其有利于绿色发展，正得到越来越多的应用。考虑到正在进行的研究，本文主要介绍如何有效地设计各种不同的屋顶雨水排水系统，并使其达到理想的设计效果。绪论在过去十年，城市与水排水系统设计已经想着广为接受的可持续发展城市排水系统或者最优管理方向发展。设计这些系统主要原则是，既要有符合当地发展水平的质量，又要为投资者创造一定的经济效益。这种原则已经引发了集水池发展方式新的变化。尽管这种装置的应用正在逐渐减少，但是城市环境要求比较高的地区仍然要求100%防水且排水迅速，例如屋顶。通常屋顶排水系统在设计、建造和维护时并没有受到应有的重视。尽管排水系统的投资费用只占建筑总投资的一小部分，但是，并不能据此来判断设计不良带来的损失。主要有两种不同形式的屋顶排水系统设计方法，分别是传统的和虹吸式方法。传统的系统依靠大气压力工作，其驱动压头受到水槽流动深度的影响。因此传统的屋顶排水系统需要一个直径相当大的垂直下降管，在排放之前，所有的装置都必须连接到地下水收集管网。与此相反，虹吸式屋顶排水系统通常设计成满管流（紊流状态意味着只需要较小的排气管），从而会形成负压，较大的压头和较大的流速。通常虹吸式系统需要较少的下降管，在负压状态下工作，意味着给水管网可以较高的高度上工作，从而减少地下管网量。两种系统都由三部分组成：屋顶，雨水收集管道，系统管网。所有这些部分都能够改变系统的水压分布。这部分主要关注各部分的作用和性能。由于虹吸系统的工作原理并没有得到很好的理解，得到的论证比较少，本文将会重点介绍虹吸系统。屋顶通常屋顶是由建筑师设计的，而不是由排水设计者设计的。主要有三种屋顶。1平屋顶平屋顶主要应用在降雨量比较少的地区和发达国家的工业建筑。这种屋顶并不完全是平的，而是低于所规定的屋顶最小坡度。例如，英国规定最大坡度为10°。设定最小坡度是为了避免任何不必要的积水。尽管平屋顶如果得不到正确的维护会产生较多的问题，但它会减少建筑物内的死区，且比斜屋顶有利于室内气流组织。2斜屋顶大多数居住建筑和商业建筑都是斜屋顶，斜屋顶最大的优点是可以迅速排水，从而可以减少漏水。在温带地区，不需要考虑屋顶承载的降雪载重。一旦下雨，斜屋顶通过的降雨量就可以通过计算确定。当有降雨资料可以利用时，可以使用运动学理论来解决这类问题。3绿色屋顶（平的或者是斜的）可以证明最老的屋顶就是绿色屋顶，它包括可以减少或驱散降雨的种有植物的屋顶。它可以是种有树和灌木的屋顶花园，也可以是长有植被的轻型屋顶地毯。其中后一种技术已经得到广泛应用。其中一些应用趋向于侧重美学要求并经常应用于绿色发展。由于审美要求和水压要求，绿色屋顶还有热绝缘的功能，减少热岛效应，有消声作用，延长屋顶的使用寿命。绿色屋顶在德国应用最为广泛，在北美地区次之，但是要考虑美学上的影响。德国是目前为止最有经验的国家，早在19世纪就有实际应用，当时作为在城市地区替代焦油屋顶降低火灾危险的一种选择。目前德国主要研究放在种植问题上，对城市的其它问题考虑较少。从1987年到1989年的一项研究工作，发现装有70毫米厚的绿色屋顶可以减少60%-80%的热损失。在加拿大的一项基于电脑模型的工作，表明在屋顶只要集水器是、的面积能够达到屋顶面积的70%，在一年内就能减少60%，同样的模型也被用于人工降雨，其结果都表明集水器在降雨季有助于雨水排走。但是这些研究都没有表明绿色屋顶在降雨季可以发挥多大的作用，或者给水管的收集效率有多高。美国做了一些测验，只要对绿色屋顶经常的浇灌，就可以在一次降雨中减少65%的径流量。美国最有权威的绿色屋顶指导原则是由新泽西州环保部门颁布的。这项原则主要是解决轻型结构问题，以及如何在两年之后还能正常的排水。降雨周期是根据是根据失败的概率决定的。通常的系统是根据暴雨期间两分钟的降雨量，这两分钟是有选择的。尽管这种模型会得到更高的流量，但是没有其他更好的替代方法。研究表明，传统模型应用于绿色屋顶的研究是是不成熟的。流失量系数比传统屋顶记录的要小，大约为7%峰值流量也会减少，虽然没有渗透，但是表面粗糙度也会产生显著的影响。集中降雨的时间要比两分钟要长，特别是对面积较大的屋顶，如公共建筑、商业建筑、工业建筑。城市排水设计还要考虑其他一些因素，对于一个复杂的系统来说，一个绿色屋顶在一场降雨中是不够的。流量水位曲线显示的持续期要比传统系统长。并且两场独立的将与之间的影响也是有可能的，这需要更加精确的时间周期。雨水收集器雨水收集器的基本要求是要能够容纳设计暴雨时的降雨量。尽管通常情况下可以通过让屋顶稍微倾斜来达到排水的目的，但是建筑工业的性质及建筑物的沉降都会式屋顶变得平坦，在水平放置的水槽中，水的剖面是向外倾斜的，这是流体静力学的作用。1排水沟出口的深度判断雨水收集器是否具有足够容积的关键是集水器外部出口的设置情况。还会影响流入雨水排水系统管道的流速，还会影响集水器的积水深度。尽管集水器的深度不会带来什么特别的问题，但是过深会导致集水器过高。20世纪80年代的大量研究表明，传统屋顶排水系统的出水口的流动情况可以分为两种情况。这取决于水深与出口尺寸的大小。当水深小于出口直径的一半时，流动情况是第一种类型，并且出口的流动情况可以通过合适的方程计算出；随着水深的增加，出口会被慢慢堵塞，流动形式会变成另一种形式，同时，出口的流动情况可以通过其他方程得出。尽管传统屋顶排水系统被设计成可以自由排水，但是设计中遇到限制可能会使出流不是自由的。在这种情况下，就会需要额外的深度。在虹吸式屋顶排水系统中，出水口被设计成淹没出流，。在这种情况下，决定出水口的深度比较复杂的，因为集水器的设计取决于流动情况。近期的研究表明，传统的屋顶雨水排水系统使用各种非标准的集水器，它们的深度和高度，都要比出口的直径大。这最终会造成虹吸作用。对于一个给定的集水器，始端的流动情况取决于下降管的直径。类似的现象也被用于研究标准的集水器，在这些情况下，受限的虹吸作用只发生在离出口比较近的距离内。2槽内的流动分类在集水槽复杂流动出口的流动分类中，可以从表2a中看出，流动会出现均匀的分层，而不管入口的流动情况是否相同。表2b和2c表明，出口的分布会极大的影响流动情况。当出口不是自由射流时，集水槽中复杂出口的流动情况分类是很难描述的。因为每个集水槽内的压力都有可能是合并的。例如，虹吸系统中的管子在靠近设计点时是充满射流，出口的流动分类取决于每个支路的能量损失。3静水剖面集水器中水表面的形状可以根据渠内流动方程进行分类。在大多数情况下，低流速意味着有较小的摩擦损失，如果出口是自由射流，那么摩擦损失是可以忽略的，静水剖面可以通过方程1来决定水平距离。式中Q--流量(m3/s)T—表面宽度（m）g—重力加速度（m/s2）F—流动面积（m2）方程1在摩擦力不可忽略时需要进行修正（管道很长或流速很大时），或者不是自由射流。4现行的设计方法先前的讨论已经强调了设计与水槽时应该考虑的主要因素。然而如果不借助于一定的数量模型，计算屋顶排水系统的静水剖面、集水槽容积是不可能的。这对大型商业和制造业来说，是一个发展机会，可以合并几千米的水管路线。因此，传统的排水系统的集水槽的设计方法主要是根据经验，并假定出口是自由射流。集水槽在建筑物中的位置，可能会造成失败的例子。不同的集水槽界面除了上面列举的情况外，还允许设计者采用经验数据。5数字模型大量的数字模型可以用来准确描述任何形式的集水槽内的流动情况，不管屋顶流量是否稳定。这种组合模型的一个例子是屋顶网模型。这种模型使用户能够对不同方面的数据进行分类说明，包括：雨季降雨情况的详细情况，屋顶表面排水的详细情况等。运动学也被用于研究雨水从流动到集水槽中的研究。一种典型的方法是基于解决开式系统中一位空间流动基本问题。这种模型自动解决集水槽出口流动情况，还能处理自由射流的情况，也能模拟空间中的受限流动以及淹没出流。输出值包括深度、流速等。目前，各种模型本质上还只是研究工具，还需要经过实际工程的检验。然而，我们应该正视模型的各种作用。4系统管组管组的组成形式和范围决定了屋顶排水系统主要依靠的是传统系统还是虹吸作用。1传统雨水系统传统屋顶雨水系统中，地面管网上面通常是垂直管网，连接着集水槽的出口和地下排水系统，重要的系统中还有补偿管。应该强调的是，补偿管与地面夹角小于10°。整个系统的能力主要依靠的是出水口而不是下降管。垂直管内的流动通常是自由流动，充满度只有33%，其效率取决于多余的管长。如果下降管足够长（通常大于5m），就有可能出现环形流动。同样的，补偿管内的流动通常情况下也是自由流动，充满度可达70%。这样设计的管路既可以用于设计，也可以用各种方程。2虹吸式屋顶排水系统与传统排水系统相反，虹吸式屋顶排水系统依靠系统外的空气流动，并且管内流动是满管流。通常的设计都做了这样的假设，对于设计的暴雨，虹吸系统能够迅速排出雨水。这种假设可以让虹吸系统应用水静压理论。经常用到稳定流能量方程。尽管这种方法忽略了进口处少量的能量损失，但经过实验表明还是有利于实际应用。然而稳定状态的设计方法在虹吸系统暴露在雨水系统时的标准不符合要求或者降雨强度的变化很大时是不能应用的。在第一种情况中，将会有一定质量的空气混入，出现环状流。这些问题在系统不是一个整体时更为严重。由于通常设计的降雨都是普通的，很明显现在的设计方法随着时间的推移可能会不适用于虹吸式系统。这是一个主要的缺点，因为设计中的主要问题是噪声和振动问题。尽管现有的设计方法有缺点，但世界上大量的工程却很少有失败的报告。当出现失败时，很有可能是下面的原因：对操作要点理解不正确不合格的原材料明细表安装缺陷维护管理不当为了克服这些缺点，最近已经开展了一系列研究工程，来讨论虹吸式系统，并发展数字模型。从这项工作中我们学到很多。与现有设计方法相反的一些假设，虹吸式系统主要有以下几个方面：1) 系统中的流动是非充满流动2) 水平流动的某些管段存在满管流3)满管流向下游传播，通过垂直管，上升管等4) 满管流出现在垂直段，系统内压力降低5）下降管内是满管流，将会出现气塞6）出现完全的虹吸作用，直到进入系统的空气低于一定的水平表4a列的数据表明，在低于设计点时，虹吸式系统会出现不稳定的流动，集水槽内的深度不足以维持虹吸作用。表4b表明非稳定流在虹吸式系统中何时会出现。表5列举了一个数字模型输出的数据。可以看出，这种模型能够准确描述虹吸作用，以及稳定虹吸状态，数据也表明该模型能够准确描述复杂的虹吸作用。5结论本文已经图示说明了屋顶排水系统的关键，但这些在城市排水系统设计中往往被人们忽视。本文也表明设计过程是一个复杂的过程，主要依靠出口的性能。下面这些结论是根据设计总结出来的：1） 运行依靠三个相互作用的部分：屋顶、集水槽、水管2） 绿色屋顶可以减少流量，美化城市3） 出口对系统的性能至关重要4） 虹吸式排水系统在大型工程中有较大的优势，但是必须考虑高昂的维修费用5） 设计虹吸式排水系统应该考虑额外的容量和操作问题尽管绿色屋顶是比较有吸引力的一种选择，但是传统屋顶在国内建筑物中将会持续占统治地位。绿色屋顶将会逐步发展，并逐步被人们广泛接受。同样的，屋顶排水系统所显示的高效表明它将会在商业建筑的排水系统中持续发挥巨大的作用。屋顶排水系统的最大威胁来自气候变化，现有的系统并不是简单的趋向于老化；降雨形式的变化将会导致低效的运行，自我清洁的速率也会降低。而且屋顶风速的变化也会加速屋顶的老化，因此十分有必要进行维修保养。考虑到气候的变化，材料的增多，收集屋顶的雨水将会更为广泛。目前，全球的雨水量大约为7到300升每人每天，在英国，平均消耗量为145L/h/d，这其中只有大约1升是人使用的，有大约30%用于厕所，研究表明，如果水资源短缺，收集屋顶雨水对发达国家和发展中国家都是值得推荐的方法。Recent and future advances in roof drainage design and performanceRecent and future advances in roof drainage designand performanceS Arthur BEng (Hons) PhD and GB Wright MEng PhDSchool of the Built Environment, Heriot-Watt University, Edinburgh, UKThe past 10 years have witnessed significant changes in the way roof drainagesystems are understood and In particular, there has been a stepchangein the confidence with which siphonic roof drainage systems may bespecified and expected to These changes have occurred whilst urbandrainage design in general has been revolutionized by wider acceptance ofSustainable Urban Drainage Systems and greater public concern regardingpluvial flooding within the context of climate This text considers, indetail, both how roof drainage systems are designed and how they should beexpected to Particular attention is drawn to weaknesses in accepteddesign Consideration is also given to ‘innovative’ roof drainage relatedapproaches such as green roofs and rainwater Practical application: Over the past few years there have been many changes inhow roof drainage systems are specified and On large buildings,technologies such as ‘siphonic roof drainage’ are now commonplace and there isan ever increasing demand for ‘green roofs’ to be specified due to their potentialto ‘green’ Based on ongoing research, this paper details howthese different types of roof drainage solutions can be efficiently designed andwhat levels of performance can be 1 IntroductionOver the past decade urban drainage systemshave moved towards what are now commonlyknown as ‘Sustainable Urban Drainage Systems’(SUDS) or ‘Best Management Practice’(BMP) Fundamental to the implementationof these systems is addressing both runoffquantity and quality at a local level in amanner which may also have the potential tooffer amenity benefits to This hasled to a change in the way new developmentsnow look and interact within However, despite the availability of such toolsto reduce, attenuate and treat urban runoff,substantial areas of the urban environment arestill 100% impermeable and drain rapidly;namely roof Normally, roof drainagesystems do not always receive the attentionthey deserve in the area of design, constructionand Although the cost of asystem is usually only a small proportion of abuilding’s total cost, it can be far outweighedby the costs of the damage and disruptionresulting from a failure of the system to providethe degree of protection Address for correspondence: Scott Arthur, School of the BuiltEnvironment, Heriot-Watt University, Edinburgh EH14 4AS,UK E-mail: ukBuilding S E R T 26,4 (2005) 337 /348# The Chartered Institution of B©u i2l0d0i5n SgASGeEr PvuicbeliscaE Aelel rrisgh2ts0 Not for commercial use or unauthorized 1191/0143624405bt127tnDownloaded from at Heriot - Watt University on January 31, 2007There are basically two different types ofroof drainage system, namely conventionaland siphonic (see Figure 1) Conventionalsystems operate at atmospheric pressure, andthe driving head is thus limited to the gutterflow Consequently, conventional roofdrainage systems normally require a considerablenumber of relatively large diameter verticaldownpipes, all of which have to connectinto some form of underground collectionnetwork before discharging to the surfacewater In contrast, siphonic roof drainagesystems are designed to run full-bore(turbulent gutter conditions mean that therewill always be a small percentage of entrainedair within the system, typically 5%), resultingin sub-atmospheric system pressures, higherdriving heads and higher system Hence, siphonic systems normallyrequire far fewer downpipes, and the depressurizedconditions also mean that much of thecollection pipework can be routed at highlevel, thus reducing the extent of any Both types of drainage system comprisethree basic interacting components: the roof surface; the rainwater collection gutters (includingoutlets); the system Each of these components has the ability tosubstantially alter the runoff hydrograph as itis routed through the This text willfocus on the role and performance of each ofthese As the principles of siphonicdrainage are generally less well understood,and certainly less well documented,particular emphasis will be placed on theperformance of siphonic roof drainage systemsin this