knowledge center


This is your hub for knowledge and information on windows and doors. Over the years, Fenesta has developed a unique understanding of how they work. This knowledge is shared through this section to help you learn what features and materials enable windows and doors to contribute to your home's comfort

Understanding Windows

A window is defined as an opening in the wall above the floor level, whose traditional function is to provide natural light, ventilation and vision. With advancements in technology the role of a window has broadened to include insulation against outside noise, protection from storms, prevent rain water seepage and reduce rising energy costs. It also breaks the monotony of the walls and adds to the overall aesthetics of your home.

Windows come in various shapes and styles, and the right kind of window can change the look of your room, home or office.

Choosing the right type of window for a particular location can be quite intimidating given the different styles, features and materials available in the market today. Here are a few things you need to know when you plan to replace those old, creaky windows.


Sliding windows

These windows have sashes that slightly overlap each other, while moving on a fixed horizontal frame. These are best suited for residential and commercial spaces where space saving is a must. They offer convenience and space

Casement windows

These windows have their sash hinged, which enables them to swing in and out, just like a door. Once again, these windows are very popular with residential plots.

Bay windows

These windows protrude out of the main walls of a room, creating a hollow bay. They are best suited for spacious rooms with high ceilings that offer a good scenic view and also add a touch of elegance to the room.

Tilt and Turn windows

These windows can tilt inwards for protection against rain and swing in like a casement window with the help of their side hinges. They are best suited when you need the slight ventilation but without the outside weather elements affecting your home.

Combination windows

Combination windows are a combination of different types of windows that deliver a completely new and stylish twist to your room.

Fixed windows

Fixed windows are those windows with no openings and these are best in spaces where little or no extra ventilation is required.

Single and Double Hung Windows

Single hung windows are fixed at the top but the bottom slides up and down like a traditional sash window. Double hung windows on the other hand, have a fixed bottom but can be opened at the top.

Awning windows

Similar to casement windows, these windows too have a hinged sash, but the hinges are at the top.

Understand your space and then choose a window type best suited for your requirement.

Framing Material

Wood and aluminium which had been the predominant material for constructing windows in the past have given way to UPVC (Un-plasticised Poly Vinyl Chloride frames) - a new-age material. Earlier, buildings were not constructed keeping in mind expansion in the size of doors and windows in summers, erosion during the monsoons and exposure to UV radiation and aesthetics. UPVC windows have changed all that and minimised the effect of these unwelcome intrusions. Moreover, materials like UPVC are low-maintenance, aesthetically attractive, energy-efficient, come in a wide range of colours, do away with the need to periodically paint the window and door frames - and don't warp.

Components of Window

Following are the main components of windows

Outer Frame

This is an immovable part of the window fixed into the aperture that was built into the wall when house was constructed

Outer Frame

This is an immovable part of the window fixed into the aperture that was built into the wall when house was constructed


This is typically an open-able part of the window, although sometimes it can be fixed too (depending on the requirement). It is used to hold the glass


Usually used for covering the openings or the gaps between window frame and the wall, a trim also doubles up as a styling accessory for the window making it visually more appealing. Trims can be applied to both exterior and interior of the window


This is the glass portion of the window and is often referred to as glazing. Two or three glasses can also be combined together to improve thermal and sound insulation. Different varieties of glasses are available and you can choose the one that meets your requirements


These are horizontal bars that divide the window's outer frame


These are vertical bars that divide the window's outer frame


It refers to the dividers (horizontal or vertical) in window sash


It is the horizontal part at the bottom of the window


These are usually metal bars that are clamped inside the window frame or onto the wall to protect against theft.

Handles & Locks

Handles are used for opening and closing the window and are fitted on to the sash of the window. Usually they are accompanied with a locking mechanism to prevent easy entry into your home

Friction Hinge

It is used for connecting sash with the outer frame. Using a friction hinge, the sash can be kept open at any desired angle.

Glazing Bead

It is used for securing the glass on the frame or the sash

Choosing the right window

Below are some of the important factors to consider while choosing the right window for your home:

  • Sound Insulation

    If you live in a crowded locality or close to busy roads, you might want to go for windows which offer superior sound insulation, so that you can have a peaceful environment at home.

  • Weather Resistance

    Like other aspects of the house, windows must be chosen keeping in mind the climatic conditions, altitude, etc. Especially if you are living in high-rise buildings or in heavy monsoon areas, it is imperative that windows withstand torrential rains and high-speed winds, thereby weatherproofing your home. Nowadays, with new-age framing materials like UPVC, it is even possible to construct UV resistant windows that neither fade, even under sustained exposure to sun, nor expand or contract with temperature variations.

  • Dust proofing

    Dust proof windows are designed to be air tight, leaving no gaps to allow dust to enter. This enhances the quality of air in your home and ensures your interiors stay clean.

  • Energy efficiency

    Windows play an important role in determining the energy costs of your home. Therefore you should consider the following energy efficiency ratings of the window profile while deciding on your window solution

    U-Factor: Ranging from 0.20 to 1.20, the lower the U-factor, the better the window traps heat inside the room.
    Solar Heat Gain Coefficient (SHGC): It ranges from 0 to 1. The lower the number, the better the window blocks excess heat.
    Visible Transmittance (VT): With a range of 0 to 1, it measures the amount of visible light allowed inside by the window. 1 indicates total visible transmittance, while 0 indicates complete opaqueness.

    An energy efficient window will not let outside heat flow in or cold-air escape out, as a result air-conditioning costs goes down

  • Longevity & Durability

    Installing low-maintenance, weather-resistant and termite-proof windows will ensure your windows stay as good as new for a long time and even outlast the building

  • Beautify Your Home Interiors

    Windows no longer serve just utilitarian purpose but are important aesthetic elements that add to the beauty of your home. With technological advancements, windows of various sizes, shapes and styles are now possible. Choose the ones that compliment the architectural style of your home

  • Save Maintenance Hassles

    If you have to get your windows repainted every few months, leading to a lot of unnecessary cost and discomfort, it is time to replace them with maintenance-free windows. These days windows made from special fade-resistant UPVC blends are widely available in the market. They do not require painting, just routine cleaning with soap and water.

  • Opt for Convenience and Optimize Space Usage

    To combat challenges arising due to space constraints, it is best to replace two-way opening windows with sliding windows. Not only is this easy and smooth to operate, but it is also quite easy to clean.

  • Maintain Privacy

    Switching to a one-way view window is best suited for those who wish to avoid peeping eyes. One-way windows make it difficult for someone standing outside during the day, to see inside the home.

The Right Kind of Installation

While the right windows can help to transform your living space, right installation is equally important. Windows with cracks or gaps, allow hot or cold air to enter the house, increasing the dependency on an air conditioner or heater. This increases your energy bills. It is recommended that you hire trained and certified installers to get your new windows in place.

Understanding Glass

Glass is amorphous (non-crystalline) transparent / translucent and is produced by floating molten glass over a bed of a liquid tin, which has a low melting temperature. Float glass is made from a mixture of sand, limestone, soda ash, dolomite, iron oxide and salt cake which are heated to a temperature of 1500 degrees Celsius.

The most common glass used is “Lead Glass” for optical use which has 24% or more lead (PbO) by weight and refractive index of more than 1.545 %.


Float or Annealed Glass

Float glass also called as flat glass is annealed glass (not tempered or heat strengthened) and is produced by controlled cooling to prevent residual stress in the glass. Float glass is high quality like sheet glass with good optical clarity like plate glass and can be cut, drilled, machined, edged, bent and polished.

Toughened Glass

Thermally tempered or toughened glass is approx 4 times stronger than annealed glass. Toughened glass is impact resistant and when it is broken it shatters into small, harmless cubes. Toughened glass is made from annealed glass which is heated to 600C and then rapidly cooled. The rapid cooling places internal stresses on the glass which allow it to be strong and break into regular cubes. After the glass is toughened, it is not possible to carry out any alteration like cutting, machining, drilling, sandblasting etc

Heat Strengthened Glass

Heat strengthened glass is subjected to heating / cooling cycle in controlled behaviour and is twice as strong as annealed glass. These glasses also have higher resistance to thermal loads. When broken, the glass fragments break into large pieces and do not result into small fragments like toughened glass, thus allowing it to stay in the opening for a longer duration. Although it is not a safety glass but this breakage pattern prevents the glass from falling and injuring someone This glass cannot be drilled / cut / edged, sandblasting etc.

Frosted Glass

Most commonly used when privacy is required, frosted glass allows light to pass through without clear view. Frosted glass is produced by sand blasting or acid etching float glass.

Insulated or Double Glass

Insulated glass refers to two or more glass sealed around the edges with an air space between the two to form a single unit. The insulating air / gas between the two layers of glass improve the thermal performance of the unit.

Laminated Glass

Laminated glass consists of two or more glass permanently bonded together with one or multiple layer of polyvinylbutyral (PVB). Used most commonly when safety is paramount. When broken, the glass pieces tend to adhere to plastic (PVB) layer. It is recommended to use toughened glass with Lamination. Toughened laminated glass invariably has waviness. This is due to glass process limitation.

Tinted (Colored) Glass

Tinted or light colored glasses are used to for aesthetic appeal or reduce direct glare and providing “soothing feel”. Tinted glass reduces light transmission and therefore proper deliberation should be done before going in for this glass.

Reflective Glass

Reflective glass is glass that has been treated with advanced coatings to reflect heat and radiation from sunlight while allowing the natural light to come in. These glasses cut substantial light and heat and are recommended to be used in double glazing (DG) format.

Borosilicate Glass

Borosilicate glass is a type of heat resistant glass which is most commonly known as Pyrex. It is not affected by changes in temperature due to its low coefficient of thermal expansion. Though sudden temperature fluctuations or rapid heating can cause it to break but instead of shattering like a float glass it is most likely to fracture in one place, making it easier and safer to clean up. Heat resistant glass is less dense than normal glass.

Glass Myth Buster

Glass plays a vital role in the performance of windows and doors. Today there are hundreds of glass options available in the market and glass manufacturers introduce many new shades / options to the customers which either confuses them or make them leave the decision to the interior designer or an architect who are in turn dependent upon the information given by the glass manufacturers.

This section is intended to remove some myths and create a basic understanding of glass and its selection criteria.

  • Myth Buster 1:

    Glass is just filling material in the window pane and does not require any wind load validation. This is not true. Windows & Doors have to pass specified wind load of the city / building. Ask your window provider for wind load chart for glass selection.

  • Myth Buster 2:

    Differential Glass thickness reduces sound. This is not true in way it is being used today. Sound attenuation works on the principle of Mass theory i.e. thicker the glass better the sound insulation properties. The differential glass thickness works when the glass mass multiplies with respect to another. This means when two glasses like 6 & 12, 5 & 10, 4 & 8 is used. It does not have any effect when we use 5&6 or 4&5 etc.

  • Myth Buster 3:

    Double glazing & Triple glazing provide better sound insulation compared to Single Glazing. This is not true. As stated in above part, more the glass mass better is the sound attenuation. This means a Single Glazing (SG) of 12mm will have better sound insulation over a DG with 6+12mm gap+6!!

  • Myth Buster 4:

    Fenesta Windows will reduce sound by 40dB This is not true always. The sound reduction is based on various factors like noise level outside, type of noise (frequency), type of construction, surrounding etc.

What is UPVC


UPVC is based on polyvinyl chloride (PVC), one of the most versatile polymers found in the century. PVC today finds application in almost all facet of our life, from daily use to highly sophisticated life saving applications. This flexibility of PVC is leveraged through a unique formulation to prepare a special UPVC blend for windows and doors.
UPVC (where 'U' stands for unplasticized) is one of the most preferred window framing material across the world. The material comes in a range of colour, is low maintenance and offers benefits which no material so far has matched. This has helped UPVC garner more than 50% market share in countries like UK, USA where it is also known as vinyl or vinyl siding.

Benefits of UPVC Windows:

UPVC windows and doors offer many of the performance characteristics which no other material so far has achieved


UPVC is prepared with a special formulation in which modifiers and stabilizers are added to polyvinyl chloride (PVC) making it rigid and suitable for use as window frames.

PVC: PVC forms the major (approx 80 - 85 %) constituent of blend composition. PVC unlike other polymer is heat sensitive and hence needs additives for processing. The property of material is such that it can be made as soft as rubber or can have strength close to any other engineered plastic. This versatility is developed through additives (like light & UV stabilizer, processing aids, impact modifier, lubricants, fillers, pigments, plasticizer etc.) which are added in PVC during the blending process.

Stabilizer - Heat & Light: As PVC cannot be processed due to its heat sensitive nature, Heat stabilizers are must to improve the stability of PVC and render it process-able. Sufficient stabilizer is required to prevent degradation of base material during processing. Lack of sufficient stabilizer may lead to early discoloration of profile when exposed to sunlight. Since windows are subject to harsh condition of Indian climate - High temperature, the formulation should also take care of endurance of profile to continuous exposure of heat & UV. This typically applies for PVC window profile in the tropical zone wherein the profile is exposed to high temperature with UV radiations. For this light stabilizers are used in recommended dosage.

Processing Aids: These are generally acrylic based material which enhances the melt strength during fusion and contributes in smooth extrusion of profile with uniform cross section.

Impact Modifier: Typically polymers tend to become brittle once subjected to low temperature or exposed to UV radiation. Acrylic based impact modifiers are used to retain impact strength even after UV exposure and at low temperature. Insufficient dosage or low cost impact modifier (like CPE) may not be able to withstand the impact resistance over long period of usage and may become brittle / crack during fabrication, installation, operation or usage.

Lubricants: These additives are used to manoeuvre the process-ability of PVC in the extrusion process. Excessive or insufficient usage of the lubricants may cause product defect.

Pigments - Titanium Di-Oxide: Titanium Di-oxide is an expensive pigment which is used as white pigment, imparting natural white colour to the PVC profile and provides the necessary UV stability for the product to have durability over years of usage. The dosage of TiO2 depends upon the UV radiation of the region. Typically the dosage ranges from 4 parts for climate similar to Europe and 10 parts for harsh tropical climate like Arizona, India, etc. The pigment also gives opacity to the product. Other pigments (organic / inorganic) & brightener are used to colour the pigment but may not have similar UV stability. These should be used cautiously ensuring the weather resistance and colour fastness.

Fillers: These are inorganic minerals (like calcium carbonate) as fine particles homogenized in the PVC blend. Usage of filler has effect on mechanical property (tensile strength, elongation and impact strength), shrinkage and cost. When used in designed proportionate improve the mechanical strength of the polymer and if used in excessive though reduces the cost but impairs the durability of product.

UPVC vs Wood vs Aluminium

UPVC is one of the most preferred window framing materials across the world and is now gaining popularity in Indian market as well due to its highly-efficient performance ratings.

So if you are renovating your home or building a new one please look at the table below for comparisons with traditional wood and aluminium. This will help guide you to make your decision

  UPVC Windows Aluminium Windows Wooden Windows
Expansion & Contraction of Window profiles can lead to product deformation

Fenesta UPVC windows is manufactured from tropical formulation which makes it durable with minimal expansion and contraction

Aluminium has very high thermal expansion coefficient as compared to UPVC, leading to product distortion if not manufactured and installed appropriately.

Wood has inherent property to breathe / absorb moisture / expand & contract, eventually leading to distortion and gaps
Insulation from Heat

Fenesta UPVC windows provides superior insulation to your home from outside heat as UPVC is a poor conductor of heat

Aluminium (being a metal) is a good conductor of heat and therefore cannot provide insulation from heat

Wood is a poor conductor of heat, however improper sealing & bending can allow heat to pass
Low Maintenance

Fenesta UPVC windows and doors require no painting, only routine cleaning

Aluminium windows and doors may require periodic maintenance over long periods of usage

Wooden windows need regular painting and polishing
Low Embedded Energy

Fenesta UPVC Windows and doors are environment friendly as they require very less energy to convert from raw material to finished good.

Aluminium window and door frames use large amount of energy in conversion

Wooden windows and doors use tropical hardwoods.
Termite Resistance

Fenesta UPVC Windows and doors are not prone to termites

Aluminium windows and doors do not attract termites

Wooden windows and doors are prone to termites
Resistance to Corrosion

Fenesta UPVC Windows do not rust or corrode due to inherent material characteristics

Aluminium windows are prone to corrosion

Wooden windows do not rust / corrode
Fade Resistant/UV Resistant

Fenesta UPVC Windows and doors are made of special UV resistant blend and therefore do not fade even after prolonged exposure to sun

Aluminium windows are typically powder coated or anodized. The powder coating, If not of high UV resistance, shall discolour quickly.

Wooden windows and doors start fading very soon ; require constant repolishing/finishing

Fenesta UPVC windows are Self Extinguishing and do not propagate fire

Aluminium windows have very high melting temperature

Wooden windows can catch fire easily
Fire Escape

UPVC windows can allow easy escape in case of fire; due to its lower softening temperature glass can be pushed out of the frame easily

Aluminium & glass both have high MP and therefore does not assist in easy break away.

Wood itself can catch fire very easily

A pioneer in Indian UPVC Window market, Fenesta's proprietary uPVC formulation and extrusion process make window frames that deliver superior performance, energy efficiency and environmental sustainability.
Aluminium windows considered here are the general / local system being used by most of the suppliers. High end designed system are not considered here for comparison.


Why should I choose UPVC?

UPVC is an excellent option for windows and doors because it is energy efficient, low maintenance and has superior thermal and acoustic insulation properties. Unlike wood, it doesn't expand or contract with temperature variations and doesn't need painting. It is also resistant to termites and doesn't fade under exposure to sun or UV rays. Compared to aluminium, UPVC is a poor conductor of heat and therefore doesn't allow transfer of heat, and neither does it rust or corrode.

Why should I choose Fenesta?

Fenesta is India's largest windows and doors brand with an experience of over a million installations in more than 1.5lac homes and several leading hotels, hospitals, institutions, offices across the country. With Fenesta customer is assured of complete end-to-end service, right from design selection, site survey, manufacturing, installation to after sales service. The infrastructure of 9 signature studios, 100 partner showrooms, 4 factories, strong direct sales force of 300+ executives, 365days customer service centre, helps us to reach out to and serve more than 100 cities in India. Moreover our products come with 10 year warranty on profiles and 1 year warranty on hardware

Does Fenesta make special sized windows?

Fenesta products can make windows and doors perfectly sized to suit your home. Speak to a Fenesta representative about custom sized products for your home.

Does Fenesta provide colour options?

Yes, Fenesta range of products comes in a variety of colour options. Click here to explore the possibilities

Where can I physically see the Fenesta product range?

You can visit the nearest Fenesta signature studio/ partner showroom / sales office in your city. Just click on the link below Locate Us

Are Fenesta products covered by Warranty?

All Fenesta windows come with 10 year warranty on profile and 1 year warranty on hardware

Do you charge a fee for an in-house estimate?

In-house estimates are welcome and completely free of cost and obligation.

What kind of service does Fenesta give?

Fenesta prides in making long term relationship with its customers through superior customer service. Fenesta has well trained professionals to look after

Window design: Designing the appropriate window based on climatic, wind load, monsoon or design considerations. Fenesta strongly believes in designing for Indian conditions and not super imposing technology used in other country conditions on Indian windows.

Window selection: trained window consultants help you chose the right window for your home

Site survey: Fenesta technicians visit each customer site to take on site measurements and advise the customer on correct timing of installation

Window installation: Fenesta has a well trained team of installers for complete window and door installation in your home in the earliest possible time

Post sales service: Should there be a need; Fenesta's service team is available to take care of any of your after sales requirements.

How can Fenesta help me chose the right window designs?

Fenesta's sales team is adequately trained to help you chose the right window for your requirements. The right design is a function of many parameters. These include:

  • Need (sound proofing, good view, etc)
  • Finish
  • Size of aperture
  • Wind conditions
  • Monsoon conditions

Our sales team will help you make the right choice for your window. They will also help you arrive at the right kind of glass and locking system.

Does Fenesta have its own installation team?

Every installation is completed by our expert team of professional installers. Fenesta's expertise in installation is unmatched. It has handled large projects stretching up to thousands of windows. On the other hand, it can provide personalized installation in an individual home taking utmost care in doing the job in quick time with minimal disturbance.

Will Fenesta take measurements of each and every window aperture?

Trained surveyors measure each and every opening before sending the window for production. It is very important as Fenesta is a factory made product and no changes can be made in it once it is produced.

At what stage should Fenesta windows be fixed?

For a high quality installation, it is critical to recognize the Right time of measurement: Measuring an unfinished aperture will lead to a wrong production. As a result, window may not fit correctly. Hence the measurement must happen on a surface that has been plastered.
Right time of installation: A home under renovation or construction is a messy place with various agencies like flooring, painting, and carpentry doing simultaneous work. Installing windows under such chaos may hamper the quality of windows before they are handed over. The right time to install windows is when the painting is almost over. Fenesta's trained installers are well trained in their job and specialize in completing installation in quick time.

Will Fenesta be available for after sales service?

Fenesta prides itself in making long term relationships with its customers. Post sales service: Should there be a need; Fenesta's service team is available to take care of any of your requirements.

Can I get spare parts for Fenesta products?

Yes. If any Fenesta products need to be replaced simply contact your nearest Fenesta showroom and ours sales team will assist you.

Upon order placement, when can I expect my windows to be installed?

Depending on the product and the manufacturer, your product delivery dates can vary. At the time of signing you will be notified of the approximate installation date.

What kind of maintenance does Fenesta require?

You don't need to do a lot of maintenance work on UPVC windows and doors: no painting, staining, or treatment. From time to time, just clean the interior and exterior frame with a standard soapy household cleaner diluted in water. And simply use a glass cleaner without ammonia for the glass.

Will the colour of Fenesta UPVC / Vinyl fade over a period of time?

Fenesta's UPVC / vinyl blend uses the highest amount of titanium di-oxide; a key ingredient required to maintain the whiteness of windows under harsh UV conditions. This ensures that Fenesta windows do not fade over sustained exposure to sun.

Who do I call if there is a service issue?

Just call Fenesta on 1800 102 9880 and speak to the window professional immediately. If a house call is needed, we will schedule a convenient time with one of our service professionals.

Is it scratch proof? What will happen if scratches appear on the surface?

UPVC window systems are resistant to scratches during normal domestic use. If scratches do appear, they can be polished out.
Still have questions? If you still have questions, please send us an email at or submit the Customer Enquiry form.


UPVC Unplasticized polyvinyl chloride

Casement Window Windows with swinging open-able parts (Sashes)

Horizontal Slider Windows/doors with sliding open-able panels (sashes)

Outer Frame The part of the window fixed to the masonry work

Sash Open-able part of the window/door

Transome Horizontal dividers of window/door outer frame

Mullion Vertical dividers of window/door outer frame

Midrail Dividers (horizontal or vertical) in a window/door sash

Bay Window A combination of three or more windows that projects outward from main walls forming a bay in a room, either square or polygonal

Tilt & Turn Window A window that tilts at an angle for ventilation and opens inwards like a casement

Multi-point locking A locking mechanism that locks at more than one point

Extrusion A process where solid plastics in the form of granules is melted in a heated chamber. The molten plastic is then forced out through a die and then immediately cooled to re-solidify to desired shape

Extruded Profile Sections made through the extrusion process

Fusion Welding A process where members are joined by heating the ends to create a semi solid area and fusing them together

Sill The main horizontal part forming the bottom of the frame of a window

Patio Door A sliding glass door used in a patio area

Rollers Wheels attached to the bottom of the sash of a window or door that allows it to slide easily

STC Sound Transmission Class ‘Higher the STC rating, better is the sound insulation characteristic of the material

Gasket The black rubber strip that runs around the pane of glass in a window to create a weatherproof joints

Reinforcements Steel or aluminium sections are used in the chambers of the UPVC profile to provide necessary strength

Single Glazing Single glass in a window is called single glazing

Double Glazing Use of two panes of glass in a window with a space in between

Triple Glazing Use of three panes of glass in a window with spaces in between

Composite Door Made from Glass reinforced plastic, it is a sturdy and stylish alternative to traditional wooden door

Low 'e' glass Refers to low emissivity glass. It lets in energy from the sun while preventing the heat escape from indoors to outdoors

'U' Value It is a measure of heat loss. Lower the 'u' value, better thermal insulation of the material

Solar Heat Gain Coefficient (SHGC) It measures how well a product blocks heat from the sun. SHGC is expressed as a number between 0 and 1. The lower the SHGC, the better a product is at blocking unwanted heat gain.