Low-e玻璃和镀膜玻璃.doc

Low-e的反射颜色为紫色。LOW-E玻璃Low-E玻璃又称低辐射玻璃，在玻璃表面镀上多层金属或其他化合物组成的膜系产品。其镀膜层具有对可见光高透过及对中远红外线高反射的特性:优异的热性能普通浮法玻璃的辐射率高达0.84，当镀上一层以银为基础的低辐射薄膜后，其辐射率可降至0.1以下。如果使用Low-E玻璃，由于热损失的降低，可大幅减少因采暖所消耗的燃料，从而减少有害气体的排放。良好的光学性能Low-E玻璃对太阳光中可见光有高的透射比，可达80%以上，而反射比则很低，这使其与传统的镀膜玻璃相比，光学性能大为改观。从室外观看，外观更透明、清晰，保证了建筑物良好的采光，又避免了以往大面积玻璃幕墙、中空玻璃门窗光反射所造成的光污染现象。镀膜玻璃按产品的不同特性，可分为以下几类：热反射玻璃、低辐射玻璃（Low-E）、导电膜玻璃等。热反射玻璃一般是在玻璃表面镀一层或多层诸如铬、钛或不锈钢等金属或其化合物组成的薄膜，使产品呈丰富的色彩，对于可见光有适当的透射率，对红外线有较高的反射率，对紫外线有较高吸收率，因此，也称为阳光控制玻璃，主要用于建筑和玻璃幕墙；低辐射玻璃是在玻璃表面镀由多层银、铜或锡等金属或其化合物组成的薄膜系，产品对可见光有较高的透射率，对红外线有很高的反射率，具有良好的隔热性能，主要用于建筑和汽车、船舶等交通工具，由于膜层强度较差，一般都制成中空玻璃使用；导电膜玻璃是在玻璃表面涂敷氧化铟锡等导电薄膜，可用于玻璃的加热、除霜、除雾以及用作液晶显示屏等；玻璃吸收能力的强弱，直接关系到玻璃对远红外热能的阻挡效果。辐射率低的玻璃不易吸收外来的热辐射能量，从而玻璃通过传导、辐射、对流所传递的热能就少，低辐射玻璃正是限制了这一部分的传热。以上两种形式的热能透过玻璃的传递可归结为两个途径：太阳辐射直接透过传热、对流传导传热。透过每平方米玻璃传递的总热功率Q可由下式表示：Q=630Sc+U（T内-T外）式中630是透过3mm透明玻璃的太阳能强度，（T内-T外）是玻璃两侧的空气温度，均是与环境有关的参数。SC和U是玻璃自身的固有参数，其含义如下：SC玻璃的遮阳系数，数值范围01，它反映玻璃对太阳直接辐射的遮蔽效果。U玻璃的传热系数，它反映玻璃传导热量的能力。由此可见，玻璃节能性的优劣由U和SC这两个参数就完全可以判定三、不同玻璃的传热特性及参数1、普通透明玻璃透明玻璃（钠钙硅玻璃）的透射范围正好与太阳辐射光谱区域重合，因此，在透过可见光的同时，阳光中的红外线热能也大量地透过了玻璃，而35m中红外波段的热能又被大量地吸收。2、热反射镀膜玻璃(阳光控制镀膜)热反射镀膜玻璃在玻璃表面镀金属或金属化合物膜，使玻璃呈显丰富色彩并具有新的光、热性能。 其主要作用就是降低玻璃的遮阳系数SC，限制太阳辐射的直接透过。热反射膜层对远红外线没有明显的反射作用，故对改善U值没有大的贡献。在夏季光照强的地区，热反射玻璃的隔热作用十分明显，可有效衰减进入室内的太阳热辐射。但在无阳光的环境中，如夜晚或阴雨天气，其隔热作用与白玻璃无异。从节能的角度来看它不适用于寒冷地区，因为这些地区需要阳光进入室内采暖。北方寒冷地区采用这种玻璃的唯一目的就是追求装饰效果。3、Low-E玻璃（低辐射镀膜玻璃）Low-E玻璃在玻璃表面镀低辐射材料银及金属氧化物膜，使玻璃呈现出不同颜色。其主要作用是降低玻璃的U值，同时有选择地降低SC，全面改善玻璃的节能特性。高透型Low-E玻璃，遮阳系数Sc0.5，对透过的太阳能衰减较少。这对以采暖为主的北方地区极为适用， 冬季太阳能波段的辐射可透过这种Low-E玻璃进入室内，经室内物体吸收后变为Low-E玻璃不能透过的远红外热辐射，并与室内暖气发出的热辐射共同被限制在室内，从而节省暖气的费用。遮阳型Low-E玻璃，遮阳系数SC0.5，对透过的太阳能衰减较多。这对以空调致冷的南方地区极为适用，夏季可最大限度地限制太阳能进入室内，并阻挡来自室外的远红外热辐射，从而节省空调的使用费用。不同的Low-E玻璃品种适用于不同的气候地区，就节能性而言，其功能已经覆盖了热反射镀膜玻璃。4、几种玻璃的综合参数以下中空玻璃的结构相同，镀膜面位于中空玻璃的第2#面（室外玻璃的内表面）说明：6C表示6mm透明玻璃，CTS140、CES11、CEB12分别是南玻热反射玻璃和Low-E玻璃型号。传热系数是美国ASHRAE标准条件下的数值。分析表明：在同等透光率下，遮阳型Low-E玻璃具有更低的遮阳系数SC，这意味着它在限制太阳热辐射的同时，并不过多阻挡可见光的透过，通俗地说，它将阳光中的热量过滤掉了。热反射镀膜玻璃获得低遮阳系数SC的代价是，这会极大地影响室内的自然采光。Low-E玻璃也叫做低辐射镀膜玻璃，是指表面镀上拥有极低表面辐射率的金属或其他化合物组成的多层膜层的特种玻璃。Low-E玻璃是种绿色、节能、环保的玻璃产品。普通玻璃的表面辐射率在0.84左右，Low-E玻璃的表面辐射率在0.25以下。这种不到头发丝百分之一厚度的低辐射膜层对远红外热辐射的反射率很高，能将80%以上的远红外热辐射反射回去，而普通透明浮法玻璃、吸热玻璃的远红外反射率仅在12%左右，所以Low-E玻璃具有良好的阻隔热辐射透过的作用。冬季，它对室内暖气及室内物体散发的热辐射，像一面热反射镜一样，将绝大部分反射回室内，保证室内热量不向室外散失，从而节约取暖费用。夏季，它可以阻止室外地面、建筑物发出的热辐射进入室内，节约空调制冷费用。Low-E玻璃的可见光反射率一般在11%以下，与普通白玻相近，低于普通阳光控制镀膜玻璃的可见光反射率，避免造成反射光污染。Low-E玻璃的生产工艺一、在线高温热解沉积法：在线高温热解沉积法Low-E玻璃在美国有多家公司的产品。如PPG公司的Surgate200，福特公司的Sunglas HRP。这些产品是在浮法玻璃冷却工艺过程中完成的。液体金属或金属粉沫直接喷射到热玻璃表面上，随着玻璃的冷却，金属膜层成为玻璃的一部分。固此，该膜层坚硬耐用。这种方法生产的Low-E玻璃具有许多优点：它可以热弯，钢化，不必在中空状态下使用，可以长期储存。它的缺点是热学性能比较差。除非膜层非常厚，否则其u值只是溅射法Low-E镀膜玻璃的一半。如果想通过增加膜厚来改善其热学性能，那么其透明性就非常差。二、离线真空溅射法：用溅射法可以生产Low-E玻璃的厂家及产品有北美的英特佩公司的LnplusNetetralR，PPG公司的Sungatel00，福特公司的SunglasHRS等。和高温热解沉积法不同，溅射法是离线的。且据玻璃传输位置的不同有水平及垂直之分。溅射法工艺生产Low-E玻璃，需一层纯银薄膜作为功能膜。纯银膜在二层金属氧化物膜之间。金属氧化物膜对纯银膜提供保护，且作为膜层之间的中间层增加颜色的纯度及光透射度。垂直式生产工艺中，玻璃垂直放置在架子上，送入大的真空室内。真空室内的压力将随之减小。垂直安装的阴极靶溅射出金属原子，沉积到玻璃基片上，形成膜层。为了形成均匀一致的膜层，阴极靶靠近玻璃表面来回移动。为了取得多层膜。必须使用多个阴极，每一个阴极均是在玻璃表面来回移动，形成一定的膜厚。水平法在很大程度上是和垂直法相似的。主要区别在玻璃的放置，玻璃由水平排列的轮子传输，通过阴极，玻璃通过一系列销定阀门之后，真空度也随之变化。当玻璃到达主要溅射室时，镀膜压力达到，金属阴极靶固定，玻璃移动。在玻璃通过阴极过程中，膜层形成。低辐射镀膜玻璃（又称LOW-E玻璃），是在玻璃表面镀上多层金属或其他化合物组成的膜系产品。该产品对可见光有较高的透射率，对红外线（尤其是中远红外）有很高的反射率，具有良好的隔热性能。 在任何气候环境下使用，均能达到控制阳光、节约能源、热量控制调节及改善环境的作用。 根据不同型号，LOW-E玻璃一般分为：高透型LOW-E玻璃，遮阳型LOW-E玻璃和双银LOW-E玻璃。 高透型LOW-E玻璃 产品特性： 1、较高的可见光透射率：采光自然，效果通透； 2、较高的太阳能透过率，透过玻璃的太阳热辐射多； 3、极高的中远红外线反射率：优良的隔热性能，较低V值（传热系数）。 适用范围： 1、寒冷的北方地区。冬季太阳热辐射透过玻璃进入室内增加室内的热能，而室内的暖气、家电、人体等发出的远红外被阻隔反射回室内，有效地降低暖气能耗； 2、适用于外观设计透明、通透、采光自然的建筑物，有效避免“光污染”危害； 3、制作成中空玻璃使用节能效果更加优良。 遮阳型LOW-E玻璃 产品特性： 1、适宜的可见光透过率，对室外的强光具有一定的遮蔽性； 2、较低的太阳能透过率，有效阻止太阳热辐射进入室内； 3、极高的中远红外线反射率，限制室外的二次热辐射进入室内。 适用范围： 1、适用于南方地区及北方地区。该产品不仅冬季限制部分太阳热能进入室内，在夏季则能限制更多的太阳能进入室内，因为冬季太阳能的强度仅为夏季的1/3左右，因而保温性能并未受到影响。从节能效果看，遮阳型不低于高透型； 2、其丰富的装饰性能起到一定的室外实现的遮蔽作用，适用于各类型建筑物； 3、制作成中空玻璃节能效果更加明显。 双银LOW-E玻璃 产品特性：双银LOW-E玻璃，因其膜层中有双层银层面而得名，其属于LOW-E玻璃膜系结构中较复杂的一种，是高级LOW-E玻璃。它突出了玻璃对太阳热辐射的遮蔽效果，将玻璃的高透光性与太阳热辐射的低透过性巧妙地结合在一起，因此与普通LOW-E玻璃比较，在可见光透射率相同的情况下具有更低太阳能透过率。 适用范围：不受地区限制，适合于不同气候特点的广大地区。1、镀膜玻璃：镀膜玻璃是在玻璃表面镀一层或多层金属，合金或金属化合物，以改变玻璃的性能。按特性不同可分为热反射玻璃和低辐射玻璃。热反射(阳光控制)玻璃，一般是在玻璃表面镀一层或多层如铬，钛或不锈钢等金属或其化合物组成的薄膜，使产品呈丰富颜色，对可见光有适当的透射率，对近红外线有较高的反射率，对紫外线有很低的透过率，因此，也称为阳光控制玻璃。与普通玻璃比较，降低了遮阳系数，即提高了遮阳性能，但对传热系数改变不大。2、低辐射(LOW-E)玻璃，是在玻璃表面镀多层银，铜或锡等金属或其他化合物组成的薄膜，产品对可见光有较高的透射率，对红外线有很高的反射率，具有良好的隔热性能，由于膜层强度较差，一般都制成中空玻璃使用而不单独使用。 3、镀膜玻璃与中空玻璃的复合体：包括热反射镀膜中空玻璃和低辐射镀膜中空玻璃。前者可同时降低传热系数和遮阳系数，后者透光率较好在线低辐射（LOW-E）镀膜玻璃是对中远红外辐射具有较高反射率的新型节能镀膜玻璃。该产品是在锡槽和退火窑内，采用CVD和MOCVD工艺将镀膜原料在高温下连续热解，沉积在移动的玻璃表面，制成低辐射镀膜玻璃。由于在高温下连续成膜，无需升温、清洗、干燥等环节，因此生产规模很大，生产成本较低，膜层与玻璃结合牢固。能单片使用并可进行热加工，是实现建筑节能必选的幕墙、窗体材料。蓝星在线低辐射（LOW-E）镀膜玻璃分为两类，一是净色低辐射镀膜玻璃，既保持了无色透明玻璃的可见光高透性能，同时具有优良的低辐射功能。二是彩色低辐射镀膜玻璃，既具有良好的透光性和遮阳性，又具有优良的低辐射功能。隔热、遮阳、低辐射都是节能概念的良好体现，承载着节能概念的各类产品的多种组合，为中空玻璃加工选择提供了可能，是实现建筑节能标准的良好基础。产品特点：高效的节能环保性：良好的保温隔热性能，是理想的节能环保材料。 优良的采光性：可见光透射比高，具有良好的采光效果。化学性能稳定：可单片使用，可长期存放，充分发挥深加工企业的自身优势。 热加工性能稳定：可任意进行钢化、热弯、夹层等各类深加工。 机械性能稳定：膜层牢固、耐磨性好、不易划伤。 在进行中空加工时，无需除掉边部膜层。 采用在线、连续生产工艺，规模大、生产效率高。 品种多样化，可生产多种颜色。镀膜玻璃也称反射玻璃.镀膜玻璃是在玻璃表面涂镀一层或多层金属、合金或金属化合物薄膜，以改变玻璃的光学性能，满足某种特定要求。镀膜玻璃按产品的不同特性，可分为以下几类：热反射玻璃、低辐射玻璃（Low-E）、导电膜玻璃等。热反射玻璃一般是在玻璃表面镀一层或多层诸如铬、钛或不锈钢等金属或其化合物组成的薄膜，使产品呈丰富的色彩，对于可见光有适当的透射率，对红外线有较高的反射率，对紫外线有较高吸收率，因此，也称为阳光控制玻璃，主要用于建筑和玻璃幕墙；低辐射玻璃是在玻璃表面镀由多层银、铜或锡等金属或其化合物组成的薄膜系，产品对可见光有较高的透射率，对红外线有很高的反射率，具有良好的隔热性能，主要用于建筑和汽车、船舶等交通工具，由于膜层强度较差，一般都制成中空玻璃使用；导电膜玻璃是在玻璃表面涂敷氧化铟锡等导电薄膜，可用于玻璃的加热、除霜、除雾以及用作液晶显示屏等；镀膜玻璃的生产方法很多，主要有真空磁控溅射法、真空蒸发法、化学气相沉积法以及溶胶凝胶法等。磁控溅射镀膜玻璃利用磁控溅射技术可以设计制造多层复杂膜系，可在白色的玻璃基片上镀出多种颜色，膜层的耐腐蚀和耐磨性能较好，是目前生产和使用最多的产品之一。真空蒸发镀膜玻璃的品种和质量与磁控溅射镀膜玻璃相比均存在一定差距，已逐步被真空溅射法取代。化学气相沉积法是在浮法玻璃生产线上通入反应气体在灼热的玻璃表面分解，均匀地沉积在玻璃表面形成镀膜玻璃。该方法的特点是设备投入少、易调控，产品成本低、化学稳定性好，可进行热加工，是目前最有发展前途的生产方法之一。溶胶凝胶法生产镀膜玻璃工艺简单，稳定性也好，不足之处是产品光透射比太高，装饰性较差。镀膜玻璃中应用最多的是热反射玻璃和低辐射玻璃。基本上采用真空磁控溅射法和化学气相沉积法两种生产方法COMMON GLASS QUESTIONSHow is glass produced?Almost all glass produced today in the developed countries is done so by the “float process”. The glass composition materials, mainly silica sand, soda ash and limestone, are melted in a furnace and then flowed on to a bath of molten tin. The glass is formed and gradually cools as it moves from the tin bath to an annealing lehr, which is a controlled cooling chamber. As it moves through this process, the glass is in the form of a continuous ribbon, which is cut to size and packaged at the final stage.What are the most common types of glass?All float glass as it is initially made in the above description is called annealed and is the most common. Float glass is made in a variety of colors or tints, in addition to basic clear glass. Annealed glass, the starting point can be further fabricated in many ways. Coatings of various types can be applied to achieve many visual effects and affect the optical properties. In addition the glass can be heat treated to increase its strength and give it safety glazing properties. Glass can be put into an insulating glass unit, meaning two or more pieces of glass are separated by a dry air space to improve the insulating properties.What is the best glass product for the Sunbelt areas of the country?Proper window design in the south must account for solar heat gain in order to help reduce air-conditioning. Therefore glass products should have a low solar heat gain coefficient SHGC or low shading coefficient SC; the u-value, or insulating performance is of lesser importance.What is the difference between long wave and short wave infrared? Short wave infrared energy comes directly from the sun but is not felt as heat. It converts into heat when it strikes something. Long wave infrared is the heat radiated from an object which has received short wave radiation, a hot automobile dashboard, for example, or a hot sidewalk or roadway where you can often see heat radiating from the surface.What are the Shading Coefficient and the Solar Heat Gain Coefficient?These terms are mathematically related and both describe the solar energy blocked from passing through a glass material. The shading coefficient is the ratio of solar energy that passes through a piece of glass relative to piece of 1/8” clear glass (which has a shading coefficient of 1.0. Solar heat gain coefficient represents the solar gain through the glass relative to the incident solar radiation; it is equal to 86% of the shading coefficient. In either case, a lower number indicates improved solar control over the 1/8” clear glass baseline.What is better, a high or low shading coefficient?In colder, heating-dominated climates such as Canada or northern US, windows with higher shading coefficients generally are preferred and conserve energy. This so because in the longer heating season, more solar radiation, which becomes “free” heat is allowed to pass into a home.In the south, with a long air-conditioning season, it is most important to reduce solar gain and therefore reduce air conditioning loads.Does long wave infrared energy only come from the sun?Any heat source, such as furnace or engine which consumes and combusts fossil fuel, release long wave energy. Any object, like a sidewalk or road or windowsill, which has been exposed to short wave solar radiation will also emit long wave infrared energy.SAFETY GLASS QUESTIONSWhat is safety glazing?Glass is a breakable material, which when broken into smaller sharp pieces often called shards can cause serious injury. Safety glazing material, usually tempered glass or laminated glass, reduces the risk of injury. This is accomplished in the case of tempered by the characteristic break pattern-many small pieces, and by the adhesion of the glass pieces to the inner plastic layer in the case of laminated glass.What is security glazing?Security glazing products usually involve multiple layers of glass, and in some cases acrylics, usually laminated, in order to achieve maximum impact resistance from explosions, ballistic assaults and even simple forced entry. There is a wide range of such specialty glass products.What are the U.S. Standards for testing safety glazing materials?ANSI Z97.1 and CPSC 16CFR, Part 1201.Where safety glazing should be used?The Federal safety glazing law stipulates that safety glazing be used in architectural applications (homes and buildings) in defined hazardous locations. Generally the hazardous location include doors, immediately adjacent sidelites, bath and shower enclosures and glazing adjacent to passages where there are walking surfaces adjacent to the glass and the bottom edge of the glass is within 18” of the floor.Are there special safety glazing requirements in overhead glazing?Many local building codes mandate special considerations for overhead glazing. It is common to require and use tempered glass in residential overhead applications. Laminated, often heat-treated glass is commonly required in commercial building applications. Often, when tempered glass is allowed in commercial building, some form of restraining screening is also required below the glass.How is safety glazing marked for identification?The Federal safety glazing law requires that all safety glazing products have a permanently identifiable marking on each piece. This marking cannot be removed without damaging or breaking the glass and is generally located in one of the corners of each piece.LOW-E GLASS QUESTIONSIs it better to have the coating on the #2 or #3 surface of an insulating glass unit?The light transmittance and U-Value of the unit will be the same whether the coating is on the #2 or #3 surface; however, the SHGC will be lower when the coating is on the #2 surface.In general, if you are concerned about reducing SHGC (typically in a cooling climate), then using the coating on the #2 surface would best meet the requirement. On the other hand, if you are interested in utilizing passive solar heat gain (typically in a heating climate) then using the coating on the #3 surface would best meet the requirement.Do all Low-E coated glasses look the same?No, they do not. Color differences between various low-e coatings are due to the use of different coating materials, the thickness of the various coating layers, as well as differences in manufacturing processes.Will Low-E glass work only in northern climates?No, low-e coated glass can work in all climates.Low-e coatings reduce heat loss from the interior through windows, thus reducing the energy used to heat buildings and associated heating costs.And, low-e coatings also offer solar control that reduces heat gain due to both the transmitted solar energy and conducted heat caused by indoor outdoor temperature difference. This reduces cooling loads and consequently the energy and costs associates with cooling the building.How can PPG Low-E work both in the summer and winter?Winter In the winter, PPG Low-E glass keeps more heat inside by reducing the amount escaping though the glass and therefore reduces heating bills. Some heat (long wave infrared) is not permitted to enter the home, but this is outweighed by the benefits of the amount of extra heat kept inside (much less heat escapes). Some short wave infrared is still allowed to enter the home and is converted into heat.Summer In the summer, PPG Low-E glass reduces the amount of heat that enters through the glass thus reducing the solar heat gain and decreasing cooling costs.How much does PPG Low-E glass reduce the transmission of ultraviolet (UV) energy?The reduction in the transmittance of UV energy is dependent on the specific PPG low-e coating and the make-up of the insulating glass unit, i.e., glass thickness, glass type, etc. Please refer to the product performance charts elsewhere on the PPG Website for specific information. The low-e coated glass improves the insulating properties of the insulating glass unit, while the tinted glass reduces the influx of solar energy through the insulating unit. How do I know that my window actually has Low-E glass?Low-e glass is plain sheet of glass that has a coating put onto one of its two surfaces. To improve the insulating properties of windows, that plain sheet of glass is put together with another piece of glass to make a sealed insulating glass unit. The low-e coating goes inside the insulating unit.You can test for the low-e coating in a window by doing the following: Hold a match or a pen light up in front of the window. You will see four reflections of the flame from the match or the light from the penlight when you look at the glass. If you have low-e, one of the images will be a different color than the rest of the images. If your window has no low-e, the four reflected images will be the same color.How does argon gas work?Insulating glass can be made with air between the lite of glass or it can be made with other gases between the lite of glass. Putting argon inside the insulating glass in a window improves the insulating value of the IG unit and the overall window. The bottom line is, less heat flows through a window with argon between the lite of glass than through a window wi