{"id":22381,"date":"2016-12-22T13:02:44","date_gmt":"2016-12-22T07:32:44","guid":{"rendered":"https:\/\/mccoymart.com\/post\/?p=22381"},"modified":"2024-05-25T16:14:41","modified_gmt":"2024-05-25T10:44:41","slug":"curtain-wall-systems","status":"publish","type":"post","link":"https:\/\/mccoymart.com\/post\/curtain-wall-systems\/","title":{"rendered":"Curtain Wall Systems"},"content":{"rendered":"
\"Curtain
\nCurtain Wall Systems<\/small><\/div>\n

With urbanization inclined perpetually towards fostering construction of multi-storeyed buildings in metropolitan and developing cities, fa\u00e7ade selection emerges as a critical component. Modern fa\u00e7ades have to incorporate functionality, durability, aesthetics and energy conservation. Building envelopes, including curtain wall systems, ventilated fa\u00e7ade<\/a> systems and sun shading systems, are all combined structurally in order to manage durability, lasting functionality, light dissemination, water, air and sound insulation, thus preserving energy efficiency of the structure.<\/p>\n

Enquire Now for Cladding & Facades<\/a><\/p>\n

Curtain wall systems, non-structural cladding<\/a> systems for external walls, are closely associated with the modernist movement in international style. In this story, we present approach to design curtain wall systems, key factors to be considered during design, cladding elements,issues affecting performance, optimisation, latest technology in the field and on intelligent glazing systems for curtain walls.<\/p>\n

Design of fa\u00e7ades depends on multiple factors. Apart from budget and overall aesthetics, design feasibility and contextual factors such as surrounding buildings, climate, end-users comfortability, interior atmospheric quality, thermal equilibrium etc. play a crucial role. The building must positively respond to all these dynamic factors.<\/p>\n

Deciding On the Type of Fa\u00e7ade<\/h3>\n

Fa\u00e7ades are not just the building\u2018s skin, they are its face as well. Beyond functional aspects, aesthetic considerations also play an important role and, sometimes, an ambitious client\u2019s aggressive demands lead to extreme designs. Selecting optimal materials opens space for creative design without compromising on engineering needs in the process.<\/p>\n

\"Khozema-Chitalwala\"
\nAr. Khozema Chitalwala,
\nPrincipal Architect of
\nDesigners Group<\/small><\/div>\n

Before delving into the extremes of design intervention on the fa\u00e7ade, it is vital to know the matter of availability of material and manufacturing technology for such design. The type of fa\u00e7ade depends on the building type and contextual climate, says Ar. Khozema Chitalwala, Principal Architect of Designers Group.<\/strong><\/p>\n

<\/div>\n
\"Mathieu-Meur1\"
\nMathieu Meur, Managing Dire-
\nctor, Meinhardt Fa\u00e7ade Techn-
\nology (S) Pte Ltd<\/small><\/div>\n

Fa\u00e7ade consultant Mathieu Meur (Managing Director, Meinhardt Fa\u00e7ade Technology (S) Pte Ltd)<\/strong> observes that deciding on the type of fa\u00e7ade to adopt the best design and materials requires close collaboration between the architect, developer and fa\u00e7ade consultant. While the architect sets the aesthetic direction, the developer provides the brief and budget and the fa\u00e7ade consultant puts it all together by providing technical advice on the various options that can be considered.<\/p>\n

<\/div>\n
\"Uttaran-B-Ray\"
\nUttaran B Ray, Founder & Man-
\naging Director, Studio Form
\nTechniques Pvt. Ltd.<\/small><\/div>\n

Uttaran B Ray (Founder & Managing Director, Studio Form Techniques Pvt. Ltd.),<\/strong> who is into boutique fa\u00e7ade design, engineering consultancy & turnkey contracting, also points out that architect provides detailed design intent. Consultants develop upon it further to make it practical and feasible. \u201cWe derive the type of fa\u00e7ade through a design dialogue between the architects and us. Fa\u00e7ade consultant\u2019s role is to approve or comment upon the interface details and structural calculations that we submit. The role is limited to performance and not really the look and feel of the envelope\u201d, adds Ray.<\/p>\n

<\/div>\n

Thus, we understand that architect has the upper hand in designing and consultants work on it to make it practical and viable. Fa\u00e7ade fabricators are obliged to go by the tender drawings\/specifications and the room to influence type of fa\u00e7ade is minimal.<\/p>\n

The Key Parameters<\/h3>\n
\"Akshat-Bhatt\"
\nAkshat Bhatt, Principal Archi-
\ntect, Architecture Discipline<\/small><\/div>\n

The building elevation is the first level of dialogue with a user, says Akshat Bhatt, Principal Architect, Architecture Discipline,<\/strong> a New Delhi based firm. It is important to understand that the elevation has to express concerns of the development and the program. He emphasizes on the importance of engaging in bespoke engineering and refined detailing in order to ensure an expressive elevation as opposed to a generic component.<\/p>\n

<\/div>\n

The fa\u00e7ade of a building is the essence of what the building stands for and selection of fa\u00e7ade design is an experiential process, says Bhatt. \u201cWe need to contemplate on the views of people as they see the building, analyse speed of cars passing by, climatological parameters etc. After considering all such parameters, we develop a building skin that has a strong architectural expression and meets the technical performance criteria\u201d, adds Bhatt.<\/p>\n

\"Gaurav-Gajjar\"
\nGaurav Gajjar, Design Team
\nLeader, Alfanar Aluminium,
\nRiyadh, Saudi Arabia<\/small><\/div>\n

According to Gaurav Gajjar<\/strong>, Design Team Leader, Alfanar Aluminium, Riyadh, Saudi Arabia, fa\u00e7ade type selection is centrally driven on the basis of project peculiarities such as architectural concept, geographical location of the project, environmental factors prevalent at site and the end user. The system type and design is dependent upon these factors and not a single aspect could be missed or taken for granted if the project is to succeed holistically.<\/p>\n

<\/div>\n
\"Nicholas-Goldsmith\"
\nNicholas Goldsmith FAIA LEED
\nAP, Senior Principal, FTL
\nDesign Engineering Studio<\/small><\/div>\n

Nicholas Goldsmith FAIA LEED AP, Senior Principal, FTL Design Engineering Studio,<\/strong> says that while developing a fa\u00e7ade, the architects would look at the building physics, orientation of the site and proposed buildings, climate zone and environmental challenges. They would provide us a sense of building mass, openness and desired transparencies.<\/p>\n

<\/div>\n
\"Hans\"
\nHans Brouwer, Principal Archi-
\ntect, HB Design Pte Ltd<\/small><\/div>\n

Hans Brouwer (Principal Architect, HB Design Pte Ltd)<\/strong> points out that the design of any fa\u00e7ade system should be determined based on a rigorous investigation into the key performance criteria and the most appropriate ways of achieving these. It is never the result of purely aesthetic concerns.\u201cIn addition to the environmental performance of a fa\u00e7ade system, we also need to take into account capital investment costs as well as downstream operational costs. All 3 elements need to be looked at holistically to determine the best solution for each project,\u201d he adds.<\/p>\n

<\/div>\n
\"antanu-Duttagupta\"
\nSantanu Duttagupta, Project
\nManager, Design2Occupancy
\nServices LLP<\/small><\/div>\n

Santanu Duttagupta (GRIHA Trainer & Evaluator, IGBC AP), Project Manager, Design2Occupancy Services LLP,<\/strong> is certain that durability or life expectancy is the key factor while designing a fa\u00e7ade system to resist environmental loads. But selection and design of the fa\u00e7ade system depends on the building type, size, usage, ownership and management team. But from the sustainability point of view, optimization of daylight and reduction of heat ingress are most important influencing factors.<\/p>\n

<\/div>\n

Khozema Chitalwala too agrees that the type of fa\u00e7ade should be simultaneous with the building system profile. Although desired as something specific, the fa\u00e7ade still depends on other intrinsic factors that include building type, easy maintenance, design style followed, thermal conductivity, availability of material in the market, operative performance, acoustics and above all assurance of safety and shelter.<\/p>\n

<\/div>\n

Design factors must fundamentally focus on having a healthy interface between the external & internal environments, meeting the desired aesthetic intent, being simple to install\/repair\/maintain, adequate design strength to bear the wind loads\/ live loads\/seismic loads\/snow loads\/thermal loads, says Gajjar. The objectives for a healthy interface relation between external & internal environment are controlled by effective water proofing, thermal efficiency, air tightness, condensation proof, acoustical insulation, maximizing natural light intake, he adds.<\/p>\n

\n
\"Charoli\"
\nPride World City Sales Offi ce at Charoli – Designers Group<\/small><\/div>\n
\"Discovery-Centre\"
\nDiscovery Centre, Bengaluru – Architecture Discipline<\/small><\/div>\n<\/div>\n

According to Santanu Duttagupta, Wind loading depends on the complexity of the building design. A wind tunnel study is important to understand the wind pressure. A full scale laboratory test can be done to check Seismic loading. Thermal performance and moisture condensation resistance capacity have to be verified to analyses thermal loading. Visual light transmittance is one of the most important factor for occupant comfort and indoor environment quality. Optimization of daylight and direct indoor outdoor visual connect are important factors as far as sustainability and green buildings are concerned. Routine maintenance is necessary to make sure the performance of the curtain wall system. Durability is measured by various structural checks (in line with above mentioned load factors) which are done prior to design finalization.<\/p>\n

Curtain wall designers also need to be aware of practical aspects of curtain wall fabrication and installation (e.g. maximum die size available, glass stock sheet sizes, metal panel sizes, etc.), opines Mathieu Meur. In addition, there are various regulatory requirements that apply to curtain walls, and these vary from country to country. For instance, some locations limit external reflectivity of glass, or set a maximum U-value and g-value that can be used. In other cases, certain materials are prohibited. All in all, curtain wall designers need to be highly versatile and experienced in order to achieve a successful outcome.<\/p>\n

Durability and Sustainability<\/h3>\n
\n
\n

Durability and sustainability is measured by quality of systems and materials which are recommended. We generally take into account various material interfaces and long term performance. Information from manufacturers is critical in the recommendation of systems.<\/p>\n

Durability and sustainability factors are researched upon at the design bid stage, which may go through many iterations to achieve the overall design intent, opines Uttaran B Ray. Available experimental data is trusted to estimate reliability of finishes, corrosion resistance, material integrity\/ compatibility, sealant degradation etc., says Gajjar.<\/p>\n<\/div>\n

\"AKH-Tower\"
\nAKH Tower, Dammam, Riyadh<\/small><\/div>\n<\/div>\n

Curtain walls are built to last longer, but are liable to have life expectancy issues if not maintained properly. Glazing, being braced on aluminium frames (malleable hence design friendly), is to be given a specific fluoro polymer coating or else would environmentally degrade. Sealant corners are prone to abrasion on prolonged exposure to moisture or heat. Along with good design principles, it becomes important for the walls to have high resistance and low emissivity values for prolonging service life.<\/p>\n

It is observed that bad workmanship and bad design are two main causes affecting durability of curtain wall systems, explains Dutta gupta.<\/p>\n

Steps to prevent bad workmanship:<\/strong><\/p>\n

    \n
  1. Certified and experience installers must be engaged<\/li>\n
  2. Regular on-site inspection required<\/li>\n
  3. Check installation sealants, fixings, gaskets, etc.<\/li>\n
  4. Review of storage and handling of the pre-cast units<\/li>\n<\/ol>\n


    \nSteps to avoid bad design:<\/strong><\/p>\n

      \n
    1. Design life consideration<\/li>\n
    2. Understanding of building physics<\/li>\n
    3. Adequate movement of the joints<\/li>\n
    4. Environmental considerations \u2013 mock ups and inspections<\/li>\n
    5. Research the product materials.<\/li>\n
    6. Design fa\u00e7ade in harmony with the structure.<\/li>\n<\/ol>\n

      Good design specs and planned maintenance are the other factors to ensure fa\u00e7ade durability.<\/p>\n

      Sustainability for any given project could be best achieved by fine-tuning the material selection\/ sourcing for fa\u00e7ades. Materials which are produced locally (ideally within a circular periphery of 50 km) and which are easy to decompose within a time frame threshold to the building design life period becomes the ideal choice. This way the sustainable buildings will not generate a residual balance to the environment upon demolition.<\/p>\n

      \n
      \n

      Selecting Between Stick and Unitized Systems<\/p>\n

      To better evaluate selection criteria, let us first understand the basic difference between Stick and Unitized Systems. In Stick systems, the individual mullion and transoms are machined in factory and the assembly with glass, pressure plate, accessories and cover cap takes place at site. The mullion-transom installation over the brackets, anchored to slab, takes place resulting in a structural grid work. This makes the system performance quite dependent upon the installation workmanship at site and necessitates the requirement of a dedicated scaffolding arrangement for installation.<\/p>\n<\/div>\n

      \"43\"
      \nAL Sebei Hotel (Train is the design theme)<\/small><\/div>\n<\/div>\n
      \n
      In case of unitized system, the complete panel fabrication and assembly (with glass and accessories) is done in a factory under controlled conditions and merely the panel fixation with bracket takes place at site with floor mounted hoist or cradle arrangement. This achieves better quality control, enables swift installation and does not need scaffolding on site. For projects which demand better performance, rapid installation and where space is limited (like crowded metro cities) for the erection of scaffolding structure, unitized system is best suited. Stick systems are generally viewed as being more economical. Since Unitized systems are pre-fabricated, they tend to be slightly more expensive to produce.Selection of system depends on the size of the curtain wall systems. For large buildings, unitized systems are apt as they are modular and are less prone to faults of bad workmanship.<\/div>\n
      \"Noor-Tower\"
      \nNoor Tower, Qatar, Doha (SMARTIA M50 from ALUMIL): Structural stick type curtain wall system, outstanding design and high energy effi ciency<\/small><\/div>\n<\/div>\n

      Unitized curtain systems can have multiple infills (ex. operable vent). They normally work best when the fa\u00e7ade design involves a high degree of repetition. On the other hand, for low-rise constructions with limited repetition or a small number of panels, stick systems make better sense.<\/p>\n

      \n
      \n

      Cladding Materials for Curtain Walls<\/strong> For curtain walls, any material from plastic to fabric to stone could be used for cladding<\/a>. Selection of material depends on requirement of expression and performance.\u201cWe have started using new age composite materials and carbon fibre in recent projects\u201d, says Ar. Bhatt. Glass is the most widely used infill material due to excellent light transmittance characteristics. Use of glass reduces internal passive lighting requirements, observes Gajjar. Glass is durable and comes with wide ranges of colour and thermal properties.Desired aesthetics is the primary criterion for selecting infill material. Once required aesthetics has been established, several possible options are reviewed in the light of the other criteria including structural adequacy, durability, availability, cost, thermal performance, etc. Infill materials could be fabric veneer, stone veneer, panels, louvers etc.,<\/p>\n

      says Dattagupta. Accordingly, infill materials could have matt, satin or glossy texture.<\/p>\n<\/div>\n

      \"President-Place\"
      \nPresident Place, Ho Chi Minh, Vietnam<\/small><\/div>\n<\/div>\n

      We distinguish between \u201cvision panels\u201d and \u201cnonvision panels\u201d, says Ar. Hans Brouwer. Where transparency (views out) and light transmission (natural lighting in) are required, vision panels are specified. In other conditions, the options for cladding material can be wide ranging from stone, to laminates to metal screens.<\/p>\n

      Enquire Now for Laminate Sheets<\/p>\n

      For cases where the solar light is not desired, there are wide range of choices available like ACP (Aluminium Composite Panels), Solid metal cladding like Aluminium wall cladding, Stainless Steel, Copper, Zinc, Titanium and Br, ceramic\/porcelain\/ clay, high pressure laminates, tensile fabric, GRC(glass reinforced concrete), ETFE, corten, etc. Here,<\/p>\n

      selection criteria depends upon the architect\u2019s intent and the theme being iconized for the project. For glass selection it is good to have low solar factor & U Value and high light transmittance.<\/p>\n

      \"An-integrated-glass\"
      \nAn integrated glass and membrane curtain wall for the Central Library in Phoenix AZ, USA, by FTL Design Engineering Studio<\/small><\/div>\n

      Materials can be combined to give a special look to the fa\u00e7ade. Besides conventional glass with infills being combined with brick and concrete to create innovative building envelopes, other cladding fills like terracotta, thin stone, HPL (High pressure laminate<\/a>), WPC (Wood plastic Composite), GRFC (glass fiber re-in forced concrete), etc. are selected to produce experimental skins on the building, notes Chitalwala. Meur considers GRC, GRP, solid surfaces, phenolic panels and other exotic materials for curtain walls other than stone and ACP. Nicholas Goldsmith says that their specialty is working with ETFE (Ethylene tetrafluoroethylene) foil cushion systems and fabric shading which can be used in conjunction with glazing systems.<\/p>\n

      Enquire Now for High Pressure Laminates (HPL)<\/a><\/p>\n

      According to Ray, Corten steel screens have large demand. Though there is an issue of staining due to a water run-off, it requires almost no maintenance while seasonally changing various tones of oxidation (rust!) Un-sealed copper is another such favourite with similar properties. Other existing processed materials include complex geometry formed acrylics and solid surfaces which are UV rated. Another trend that we notice is the requirement for energy related performance skins.<\/p>\n

      Prior deciding the cladding material to be used, one must also consider how the visionary access (opaque, translucent, transparent) goes in tandem with other instances such as reflectiveness, choosing the type of glass (triple glazed\/double layered), its thermal conductivity, exchange of light, heat and air, responsive outcome of an altering climate (day and night), the need for a sustainable integrated fa\u00e7ade, etc. The market availability and constraint on manufacturing could collide with the planning and completion time as well. However, since each material exhibits different properties based on the above list, it is essential that the whole vertical curtain performs as an entwined system.<\/p>\n

      Safety is also important selection criteria. For the balustrade, skylight or children play area applications, laminated glass is an ideal choice. Post breakage, laminated glass has the ability to hold the broken glass pieces in place thereby minimizing direct injury risk, says Gajjar.<\/p>\n

      Key Factors Escalating the Performance of Fa\u00e7ades<\/h3>\n

      According to Dattagupta, design is the most important stage to optimize the performance of a curtain wall. We need to study the building\u2019s profile and orientation. Shadow analysis and sun path analysis are important. One needs to consider heating cooling load and daylight too before the selection of best fa\u00e7ade material\/combination. Fa\u00e7ade maintenance aspects are also crucial. Ar. Chitalwala too agrees to this. In addition, one need to consider energy exchange loads, glazing ratios, periodic changes of shading according to overhangs, etc. These aspects, well in accordance with the building\u2019s profile, need to be clubbed with the occupant\u2019s productivity and well-being.<\/p>\n

      It is important to understand both the inside and the outside of a building\u2019s fa\u00e7ade to evaluate it correctly. Some of the essentials for performance evaluation are: daylight ingress, night time expression, heat bridges and dew points. The architect\u2019s skill really lies in being able to translate building physics parameters into an expressive construct, says Ar. Bhatt.<\/p>\n

      Gajjar points out that the most critical factor improving performance of a fa\u00e7ade is its ability to provide efficient weather proofing,to enhance the solar performance the fa\u00e7ade, the material must have a higher resistance to the heat flow i.e. lower U value and a lower solar factor applicable for glasses. Pressure equalized rain screen principles play a vital role in enhancing the weatherproofing and thermal performance of fa\u00e7ades. Another crucial aspect to consider at design stage is accessibility for maintenance.<\/p>\n

      Thermal Performance of Curtain Wall Systems<\/h3>\n
      \n
      \n

      Thermal performance of curtain walls play an important role in resisting the inflow or outflow of heat energy. For the projects in hot regions, the objective is to reduce the solar heat influx to reduce the cooling load. Whereas in cold regions, it is imperative to retain the internal heat to reduce load on heating systems. According to Meur, in a high-rise air-conditioned building, the fa\u00e7ade can contribute in the range of 30 per cent of the total heat load on that building, with the rest coming from internal equipment, human occupants, etc. If the building envelope is made 30 per cent more efficient, then this could represent a reduction in the total heat load on a building of about 10 per cent, which is substantial.<\/p>\n

      According to Gajjar and Dattagupta, thermal performance of fa\u00e7ade systems could be improved by incorporating a non-metallic, low conductivity infill material to create an insulating effect. Common insulation infill materials used are polyamide (PA) and polythermide (PT).<\/p>\n<\/div>\n

      \"ad\"
      \nRMIT Design Hub, Melbourne by Meinhardt – The glass shading disks are individually controlled via a computer so as to optimise daylight harvesting and minimise heat gain<\/small><\/div>\n<\/div>\n

      PA has better thermal performance and rigidity then PT; however, it is twice as expensive as PT. Another way to enhance the thermal performance of system is by increasing the number of gasket and its contact with the AL section or by having more air pockets. Use of soft coat, low E coatings have a major impact on solar passive heat gain.<\/p>\n

      Thermal conductivity of the curtain wall is important as the heat loss\/heat gain directly affect the heating\/cooling cost of buildings. To improve performance, thermal breaks of are incorporated. Pressure bars are also used in some of the systems. Maintaining the continuity of the air barriers at the perimeter reduces airflow around the curtain walls. Aluminium is normally used for curtain wall framing due to its light weight. However, heat transfer coefficient of Al is high and therefore there is a tendency of heat loss\/heat conduction through Al curtain wall mullions.<\/p>\n

      \n
      According to Khozema Chitalwala, certain buildings may opt for single glazing where the interior operations does not matter, hence no specific requirements besides cladding. However, the insulation and conductivity depends on reflective coating applied to the glazing and single\/multiple layering.Besides the purely thermal aspects, curtain walls also play a key role in limiting air infiltration, thus minimising the risk of condensation and mould formation.<\/div>\n
      \"Pride-World\"
      \nPride World City Sales Office, Charoli, Pune – Designers Group<\/small><\/div>\n<\/div>\n

      Reducing Construction Cost<\/h3>\n
      \n
      \n

      Repetition of details and modules brings down the cost of fa\u00e7ades, says Meur. Unusual modulations, particularly very large or non-rectangular panels, contribute to additional costs due to excessive wastage and higher shipping charges. The unit rate for granite from Brazil or a travertine<\/a> from Italy is higher than that of a composite aluminium panel<\/a>, for instance. Interestingly, some developers want to explore adopting window walls (floor-toceiling glazing) as a cheaper alternative to curtain walls. This may not necessarily be effective, as window walls require more brackets, anchors and sealant, scaffolding for external access, and more importantly, they reduce the NLA (net leasable area) substantially. The same applies to increasing spandrel areas to save on supposedly more expensive vision glass.<\/p>\n<\/div>\n

      \"CIS-Tower\"
      \nCIS Tower, Manchester: BIPV (building integrated photovoltaics) on fa\u00e7ade<\/small><\/div>\n<\/div>\n

      While it is true that monolithic or laminated spandrel glass is cheaper than a double-glazed vision area with coating, the unit rate for spandrels is often higher than that of vision areas when you factor the additional powder coated<\/a> back-pan and foil-backed insulation.<\/p>\n

      Latest Technologies and Trends in Curtain Wall Systems<\/h3>\n

      Development of more \u201cintelligent\u201d glazing systems have radically altered the energy balance of traditional curtain wall systems. Double-glazing has improved insulation values significantly and intelligent coatings, such as low-e, have reduced the impact of direct insolation (sunlight coming into the building) and the resultant heat loading on the interiors.<\/p>\n

      The nascent trend of fa\u00e7ade integration that includes amalgamating various power influx techniques providing energy-efficient buildings, are gradually taking lead. In response to keeping the interior air quality comfortable, these active fa\u00e7ades tend to perform strategic mechanisms that control solar heat gain\/glare infiltration, effectual ventilation, harvesting daylight, thereby reducing the building\u2019s gross energy consumption. Some examples include rain-screen fa\u00e7ades, BIPV (building integrated photovoltaics) (CIS Tower, Manchester), automated shading and transparency controls (Eskenazi Hospital, Indianapolis), effective day lighting, multiple infill unitized systems, Nano coated ACP<\/a> (in gulf countries), etc.<\/p>\n

      \"Antony-John\"
      \nAntony John, Engineering
      \nDirector, Schueco India<\/small><\/div>\n

      According to Antony John, Engineering Director, Schueco India,<\/strong> following are the latest technology in curtain wall systems:<\/p>\n