System Windows Design Factors

The word system itself indicates the windows are designed in a proper methodology & with a purpose to fulfil Performance in terms of function. Three important aspects the windows are designed for

  • Environmental Factors
  • Materials Factors ( Aluminium Extrusions, Hardware & Fitting accessories)
  • Quality Workmanship Factors.

These terminologies were never discussed in India but with the current trend of high rise Structures major factors effecting like Wind, water, heat, air leaks etc became a challenge against the smooth performance of the Windows.

Environmental Factors

Wind Loads

Indian standards wind speed codes Is 875 Part III discusses the Wind speed city to city. The formula to arrive at Wind Loads also cater to Building location, terrain factor, Height, Width & Depth of the building. Multiplication of all these factors constitutes to Wind Load in (KPa) Kilo Pascals.

Whole system calculations are evaluated using the wind load & size of sections are derived to sustain the loads.

Water Drainage

The major challenge for any window during rains is to cater to drainage of water from the track, against the wind force blocking the drains. This is a dynamic situation any system window has to address. Conventionally drains caps are too design with flaps for high rise windows. The materials for cap is also selected considering the life of Window for minimum 10 years.


There are various sources of heat coming in a window through

  • non solar conduction, convection & radiations. ( U Value of Window)
  • Solar heat gain through convection.
  • Air flow by means on ventilation & another by means of infiltration.

Materials Factors

Aluminium Extrusions

Aluminium extrusions, a technique used to transform Alloy into any shape with defined cross sectional area. Aluminium has unique physical properties its malleability allows to be easily machined & cast. The most unique property of Aluminium is it is Non corrosive & at the same time provides enough strength & stability for use in Architectural products.

Aluminium once alloyed with other metals provides strength & mechanical properties to bear the strength. It can also be coated easily with 3 different processes Anodizing, Powder coating & PVDF coating. PVDF coating is now widely used due to high resistance to UV rays and allows the gloss retention up to 70% over a period of 20 years.



Corner cleats, Locks, bearings, Anti lift, drainage cap constitutes major hardware components in any sliding window. All system windows have these components & their performance in terms of operations counts the most.


A bearing which is the most important element of window needs to be used based on evaluations of dead load of glass & cyclic testing with N number of cycles tested. These data from the vendors must be taken. Very few companies like Lavaal, Giesse have these testing facilities & provide the data. Locks the second most important component needs to be tested as well for cyclical locking so that the springs & joinery perform well.

Rest all components corner cleats, drainage cap materials always need to be examined or tested for those components to perform for 10 years.


Quality & Workmanship

With all things right Aluminium extrusions, Coating, hardware, EPDM gaskets, wool pile one has to ensure the fabrications machinery used is proper to get 45 degree & 90 degree joints precisely machined. The tolerance factor in machining must be very minimum so that the end product is right.

In the installation stage also use of sub-frame on site is preferred as this helps to standardize window sizes. The labour team has to ensure all the water levels of track shutter are thoroughly inspected on site to give a right end product.




In order to achieve a problem free Window one has to focus on System Windows as the best option. Also note system windows Aluminium consumption is marginally higher than the normal windows, but the major difference is in the hardware used.


There is a difference in terms of performance & comfort in operations.


If you are looking for any system Window design & development we @ can help you source the right window for your project.


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Or call @ 08652446321


Sliding window constitutes majority of Home in Indian Market from Bungalows to high rises. Indian climate is a challenge for Window system suppliers as all seasons Summer, Winter & Monsoon equally poised over span of more than 2 to 3 months. Hence for the same window to pass these climate test becomes equally challenging.

More than 70% Homes have Sliding Windowsdue to economy of cost & ease in functionality. Architects too had a challenge of Sight line aspect for it to look sleek in elevation hence opted more of Sliding Windows.



Conventionally Structural aspect in sliding window was never discussed until in last few years, with High Rise Structures coming in, increased the Wind loads on the Windows. With speed of Wind & during rains performance becomes challenging as all the materials used may not perform up to the mark. The track design also becomes challenging where one has to understand the co-relation between Collection & drainage of water against gravity.

Major Design Aspects of Sliding Window:

  • Always insist on checking Structural stability of the window in terms of wind loads & dead loads of the shutters.

  • Ensure design of gutters is studied with intake & outlet water into the track.

  • Check the strength of the glass with respect to Wind loads, consider safety aspects in event of breakage due to some reasons.

  • Check for use of Proper corner cleats for outer frames and shutter frames as these joints should not get loose over life of a window.

  • Proper Locking systems helps in preventing from Burglary, Proper operation of day to day locking & functionality. Always use locks duly tested with N number of cycles.

  • Most important aspect of any sliding window is Rollers. Always ensure you ask the roller manufacturing companies the data at which they have tested it right from Surface Materials, SS used in rollers, dust contamination must not be there.

  • Most importantly materials used must be corrosion free. As these hardware should have a life of at least 10 years once used.

  • Workmanship plays an important part as despite efficient design if not installed properly you can have sliding issues. One has to ensure all hardware like Locks, Rollers, Anti Lift, Corner cleats, Sealants & various things must be properly installed on site.




Window testing at leading laboratories can now be done in India. These test are defined as perASTM / AAMA standards. Testing builds confidence in Contractor, Developer & designer to see the performance of sections he is using on site. In event of any failure during test the corrections can be implemented so that on site failures do not occurre.

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Sustainable Facades

One could have observed an absurd climatic change in the country where sudden rains, unbearable heat & lot of climatic issues arising. With the modernization of building facades lot of glass buildings coming up there is a need for Sustainable Façade.

The modern façade becomes Sustainable in regards to the thermal & functional performance not compromising on the aesthetics.


For any building two important aspects come to the developer

  • Investment on the construction of facade.

It is preferable for any building façade to be durable on the long run & usage of recyclable materials needs is increased. Fortunately most of the façade materials like Aluminium, Glass, ACP, Solid cladding has reusability properties, and one can recycle & reuse them.

  • Operating cost of the facade.

People have a tendency that as they are not the occupants of the buildings any low quality materials can be used & somehow the façade needs to be completed.

This is a wrong approach as in today’s scenario Operating cost is very high in terms of Electricity bills of HVAC, Lighting & various mechanical utilities used in a building. So it must be very crucial for the designer to save energy as & where possible. For example Glass is major transmitter of heat inside the building, hence Glass can be designed to suit the climatic conditions.

Core Aspect of an intelligent façade:

Façade are responsible for the comfort of the occupant within the building & at the same time consumption of Energy. One needs to incorporate various strategies to achieve Low Energy consumption in a building.

Various important Aspects of Effective Design:

  • Maximizing Day Lighting Strategies.
  • Blocking Heat in South & South West Area using Louvers & Blinds.
  • Insulating the Spandrels to block the heating of RCC structures.
  • Generating Electricity by using Photovoltaic cells.
  • Utilization of Pressure Differentials.

Classification of Intelligent Facades:

  • Single Skin Façade.
  • Double Skin Façade.
  • Combined Façade

Single Skin Façade:

To achieve a certain level of Solar Control in Single Skin façade following things to be done

  • Use Effective Solar Control Glass with Low Solar Factor & Low U values.
  • Use of better Gaskets (EPDM) to thermally break the heat transfer of conduction.
  • Pressure Equalized facades helps in proper Air Circulations inside the chambers to drive water & heat away trapped inside.
  • Use of perforated Panels in high heat areas to have optimized day lighting & blocking unwanted heat.
  • Various Internal Shading strategies can be adopted to block the Glare & incoming heat.


Double Skin Façade:

The term double skin facade refers to an arrangements with a glass in front of the actual building a facade. Solar control devices are placed in the cavity between these two skins, which protects them from the influences of weather and air pollution.

  • Solar shading helps achieve optimized temperature inside.
  • Re-radiation from the solar radiation is emitted in the central cavity.
  • Better Sound Control by creating a cavity in between two facades.
  • Widely used in high rises to have less effect of wind & cavity helps as natural ventilation zones.
  • Very Expensive in terms of cost, so very few building used.


Combined Facades

This is combination of single & double skin facades by providing a baffle panel in the vision area helping in reducing noise levels in the building.

  • Baffle panel is an additional panel in front of a window in a perforated or conventional panel.
  • Baffle Panel blocks lot of sound comes from the primary façade.
  • Baffle panel helps in solar screening.
  • Baffle panel needs to be openable for cleaning, & ventilation.



Because of reduction energy resources and increasing cost in the world every day, energy conservation in buildings primarily focused on building systems. After 2010, targeting the energy crisis, which can produce its own energy, ventilation, heating and cooling that provides “intelligent facades” came up.

No doubt in the short run these facades are expensive but in Long run they pay you back in terms of Cost, Better Environment & Sustainability.


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Role of Façade Management Consultant :

Day by day increase in demand for facades has brought up lot of challenges with Architects aiming for complex designs catering to demand in façade Management professional.

  1. Approvals of Installation drawings.
  2. Quality auditing of raw materials coming at site.
  3. Quality of Installation.
  4. Safety Issues of Labour.
  5. Final Handing Over & Certification.

Approvals of Installation drawings –

  • This stage is most important stage for the Professional to know what is going to be done on site understands the Façade systems, shop drawings & methods of fixing.
  • Figure out the wall types & their detailing for fixing on site.
  • Approve the right drawings or ask for corrections in the same.

Quality Audits of Raw Materials coming at site –

  • For any façade to perform for cycle life of building this is the most important aspects as materials need to ensured for quality checks randomly.
  • Aluminium extrusions, coatings on Aluminium, bracket quality, Glass processing, Anchoring on site, Glazing process, EPDM quality audits & various other quality processes needs to be documented.
  • ASTM / AAMA / Australian/ EN/ BS standards are various international standards which clearly mention how to carry out process of checks of raw materials. These test needs to be done in order to have right materials on site.
  • One can have random checks because glazing system failures starts from materials failures only.


For example:

Aluminium extrusion –

No one can keep on checking all the supply coming from factory, but one can bind the vendor with either rejections or penalty in event of poor quality materials. Basic checks like thickness of materials, diagonal inspection of hollow materials, Twist & bow along the length are mandatory checks need to be done.


 Glass Inspections –

There are various instruments now available to check surface compressive stress on glass without breaking the glass, these checks must be documented. Rest issues such as diagonal size mismatch, edge arising, improper grinding needs to be checked as any of could be the reason for onsite breaking of tempered glass.

To avoid quality issues a inspection of factory of the vendor is must so that he can supply right glass.

 Double Glass –

Hardly few contractors get a prior approval of Silicone byte size used in the making of double glass. In some cases even not mentioning the work in PO Silicone sealant itself might create a quality gap where processor might use Poly sulphide sealants.


EPDM Gaskets –

These gaskets are on the low cost items in the whole façade materials but these are the important barriers one has to look into. Without gaskets façade fails in thermal transmittance of heat & prevent air & water leaks.

Buying a low quality PVC, EPDM gasket could lead to disaster as failure of joints cost a lot. Hence before selecting a Gasket understands its Thermal conductivity properties so that it has to perform over the life of façade. Once cannot replace these gaskets easily as it is integral part once fixed cannot be accessed.


 Structural Sealants –

We always emphasize on Contractor asking for warranty from the silicone supplier & document it. All materials are inspected by the sealant supplying company & a compatible test is conducted. After this test it comes to physical inspection


  • Onsite deglazing process must be followed in guidelines of sealant supplying company.
  • In case of single part silicone compatibility between open cell tape & silicone must be done.
  • In event of 2 part sealant proper butterfly test needs to be conducted so that mixing of sealants is done properly for better adhesion once applied.
  • Sealant applicator must be trained with respect to guidelines of sealant training manuals.
  • Finally after carrying out the process get the final onsite warranty from the Suppliers.

Weather Sealants-

Application of weather sealants is more risky affair as lot many people I have observed tend to use General purpose silicones which is ready across the counter in many small projects & in the event joints fail in the very first year of application. Before considering weather silicone following steps need to be understood

  • Get the application manual from silicone sealant suppliers in order to understand the properties of the same.
  • A proper byte size must be derived in proportion of 2:1 guidelines in the manual ( Ex It Width is 12 mm then depth needs to be minimum 6mm so that the joint is properly formed)
  • Also use proper bonding primers as specified by the silicone sealant manufacturing guidelines in order to get best adhesion.
  • Cleaning of surface is must & always ensure application of backer rod is done properly to get the byte size.

Similarly all the raw materials coming to site needs to be checked & their application methods need to be followed as per standards.

Quality of Installation –

This is most important element in the façade construction & needs lot of expertise. I have seen despite high end factory manufacturing if the product is not installed properly it ends up in disasters.

In the past 2 to 3 years we have got lot of projects for rectification the largest being a 40 storey high rise at Mumbai, where lot of areas were subject to water leaks & client being a hotel was irritated with the façade.

We conducted lot of inspections & also suggested the clients with external capping in order to prevent the water entering the groove, but due to looks we stayed with a glazed façade & rectified it using our team on gondola sealing the biggest façade.

I would say always plan your installation & understanding of fixing systems is most important. Water levels, Plumb & respective gauges needs to be inspected periodically on site to ensure product is rightly installed.

We have done many projects in India, Mauritius where the extent of wind loads ins up to 3 KPa, working conditions are breezy throughout the year .

One has to ensure proper site supervision & document inspection dates & time so in event of any issue can reach the person & understand why failure happened.

Safety issues of Labour –

Glazing is a field where I have observed despite lot of complicated designs on paper our whole future lies in the hands of labour as their work will bring you the credit of better workmanship.

Labour safety rules must be followed begins with Helmet, Safety belt, Shoes , Proper access space on site needs to be provided. You cannot take any uncalculated risks on site because safety of labour is most important for you.

We also need to get the insurance for labours so that in event of any mishaps the costs are covered by the company.

Final Handing Over & Certification

After all the work is over on site one has to properly clean the site & hand it over to the clients. We also have practised a method where we document all the test certificates of materials supplier & Silicone warranty Certificate & Hand it over to the

Clients for documentation. These also contains phone numbers of the vendors so in event of any failures once can be easily reached.


written by: Satish Jadhav (Director Mascon Facades)

Satish Jadhav, having 20+ years experience in the façade field worked with leading companies like Sp Fab, Alufit, Ajit India, FCD consultants & presently works independent in Façade Management Consulting.

He has worked on Various Indian Projects Siemens Bangalore, Oracle Bangalore, IT Park Mauritius, SD Towers Mumbai & more than 100 projects where he completed. Recently he is doing a rectification work at a 40 storey building at Mumbai to prevent leaks & rectify some façade elements.

Contact – 09769271616




 2008 was a big year for China as Beijing had won the bid to host the Summer Olympics. The Chinese Government had grand plans to prepare their country as host nation for this worldwide event. Included on the list was a state-of-the-art, eye-catching facility from which China Central Television could share the Olympics with the world.

 China Central Television

 A Geometric Wonder

Standing in a Seismic Zone

GE Silicone and Comprehensive Technical Expertise Critical to CCTV Construction


The Challenge:

 Connecting Two Buildings in a Seismic Zone:

The winning design, shaped like two “L” shaped high-rise towers linked at the top and the bottom at an angle to form a loop, best described as a “Z criss-cross,” was planned for a modest 234 meters. However, the building’s unique shape created an irregular grid on the building’s façade with an open  center, a challenge for a structure that connected two separate buildings on a foundation in the middle of an earthquake zone.

Constructing 27,400 Pieces Safely and Quickly:

The building, centered with a curtainwall façade, required 27,400 pieces, all of untraditional shapes and sizes, to fit within an irregular structural frame totaling 100,000 square meters (~1.1 million square feet). In addition to the many pieces, the designer and the fabricator determined that the safest way to construct the many pieces into a “Z” shape was with “L” shaped joints, which were longer in vertical length than horizontal length.

The challenges mounted:

Irregular geometric pieces take longer to manufacture and install; safety for everyday use and within seismic conditions was paramount; and the international stage of the Olympics presented a hard, quickly-looming, deadline.

location: Beijing; China.

challenge: The buildings unique shape created an irregular grid on the buildin’s facade with an open centre, a challenge for a structure that connected two separate buildings on a foundation in the middle of an earthquake zone.

number of floors: 49 floors.

building height: 234 metres

structure: Shaped like a “Z criss cross” in Beijing’s central buisness district; with an earthquake zone.

products: GE SSG4400 UltraGlaze*, GE SSG4800J UltraGlaze*

(custom multi-part mixture), GE SCS2903 SilPruf*, Pensil 300


The Solution:

 Excellent Technical Support and Sealant


Mechanical Properties:

The Chinese Government selected Beijing Jangho Curtain Wall Co., Ltd., the second biggest curtainwall fabricator in China, as the façade fabricator. The manufacturer of GE sealants and Jangho have had a strong history of collaboration and success.

“We needed a partner who had both a technical product advantage and the ability to manage the inevitable technical challenges that would come in creating a building with such an unusual design,” says Zhang Sheng, vice president at Jangho.

While Jangho recognized GE Sealants as excellent products, it would take more than that to construct the China Central Television (CCTV) building. Basic geometry implies that two equal size triangles will create four-sided shapes. The challenge was taking irregular geometric frames with lots of triangles within a system designed around rectangular calculations. Assembling such panels makes the dimensions difficult to control, so every millimeter counted, and excellent adhesion and flexibility to stick on the panels was critical.

In addition, to meet earthquake safety standards, the fabricator selected dual-laminated insulating glass, so the structural sealant needed to be applied into an “L” joint through narrow openings. Conventional SSG joints require a +/-12.5 percent movement. In examining the “L” joints needed for the project, the sealants team of technical experts determined that a +/- 15 percent movement was necessary.

“The technical experts for GE sealants spent countless hours working with our design department and going back and forth between the work site and our Beijing plant to find a solution for the uniquely sized pieces and “L” shaped joints,” says Sheng.

“Together we tested to find the right product that had the product consistency to fit within the sealant joints; and that is why we selectedGE sealants for the CCTV.”

Redefining Limitations:

The technical experts for GE sealants had clear challenges to consider in recommending the right mix of products. The design process resulted in two towers that, as independent towers, were prone to movement from the wind and surface temperature variations due to the amount of direct sunlight or shade on any given elevation.

GE SSG4400 UltraGlaze*, a high-strength, two-part elastomeric adhesive sealant for structural bonding, passes the ASTM C719 movement test at Class 12.5. Due to the large size of glass and the “L” shaped joints, +/-15 percent movement capacity was deemed necessary for this design. The sealants team conducted multiple tests on the work site and at Jangho’s lab to help determine that, with its excellent processing and flowability (which allowed the sealant to get within the uniquely shaped joints), coupled with its ability to accommodate the additional 15 percent movement,SSG4400 had the properties needed to successfully and safely construct the building.

Through a thorough analysis and deep technical discussions between the fabricator curtainwall providers and the sealants team, it was determined that SSG4400 would be “pumped” into the uniquely shaped joints. The consistency of SSG4400 in testing proved to be both viscous enough to hold the joints stable during the cure phase, as well as capable of flowing into tight spaces while thoroughly filling the cavity within.

The Result:

The CCTV building was completed in January 2008. Start to finish, the façade fabrication took about 18 months—six months quicker than the average for a building as complex as CCTV.

To stay on track with the aggressive timeline, Jangho ordered all of the aluminum extrusions and pieces prior to involving the sealants team. If Jangho, with the help of the sealants experts, hadn’t found a solution to the “L” shape joint, the project would have been significantly delayed and the original aluminum order would have been wasted.

“One of the reasons we partner with the manufacturer of GE sealants is because we are a local company and they are a global company,” says Sheng. “Once again, they helped us with global experience, tapping into their experience so that we could best serve our customer through their sealant laboratory and excellent training programs.”

Pioneered by GE. Refined by GE. With a history of dedication to innovation and excellence, today’s family of GE sealantproducts address a wide variety of the ever-inventive, increasingly demanding architecture found around the world. Outstanding durability, flexibility, and movement capability are fundamental to the high performance of GE sealants. With decades of experience, in new and remedial applications, on some of the world’s most innovative structures, the GEsealants team provides knowledge and comprehensive support to help ensure a project is successful.


APPLICATION: Each customer should determine the suitability of Momentive’s materials for the customer’s particular use through appropriate testing and analysis. Due to variability of substrates, testing for substrate compatibility is recommended. Appropriate surface preparation is required. Actual results may vary.

The participants in the CCTV project mentioned herein are provided solely as historical background information. This advertisement does not constitute an endorsement from such parties, except to the extent expressly provided herein.

GE is a registered trademark of General Electric and is under license by Momentive Performance Materials Inc. Huntersville, NC 28078.