Post 644 –by Gautam Shah


Windows are surface elements with great presence on both exterior and interior sides. It is fairly a complex entity against the comparatively simplistic wall, but a surface that is penetrable. Its surface is very dynamic, due to the continuous variations in views through it and the vivid reflections on the glass surface. The contextual conditions like climate, illumination, distance and angle of observation and the purpose of use and multifarious position of the shutters continuously reshape the perceived form of the window.

The external changes are reflected as a reverse mirror image in the glazing surface, and the interiors get revealed through an iridescent surface. A window, as a single picture frame, simultaneously reveals the changes occurring in the interiors as well as exteriors. The dynamism of the window gets enhanced further by the framing, masking and filtration of the perception.


Looking out Chand Baori Stepwell Rajasthan India Flickr Image >

A window is like a membrane with degrees of permeability. It may not permit one to go through it, but allows to stretch out through the sensorial faculties. We see, smell, listen and feel the other side through the window. The connection to the other side of the window is always short and casual. The frugal experience stimulates one to go across it, albeit by other means. Doors are dilemmas, either go out or remain in, but a window provides no such options. A person on outside of a window perceives the safety in the interior, and the one in a bounded space realizes the freedom and diversity of experiences available outside. Windows have been used for opening out the interior spaces or for bringing in the exteriors.

Pecs Zsolnay Architectural District Building

The historical window with opaque glazing of heavily coloured pot glass was extremely colourful but dead static. As the glass became thinner and lighter in colour, the changes in outside levels of illumination began to be noticed on the interior face. This was aided by the use of water white Cristallo glass. Interiors seemed now much more natural, and attuned to the outside changes in luminescence. Till 19th C windows were vivid elements in an otherwise static exterior or interior surface. The Cristallo glass, outside was a dull metal like an opalescent surface, but new clear glass with better casting, polishing and fire finishing began to be iridescent.

The glass was recognized as having two distinctly different faces. Iridescent on the outside face due to reflections and a ‘water-white’ flawlessly clear and non glossy surface on the interior face. Corbusier used the opaque iridescence of the exterior surface to juxtapose the exterior masonry or cement surfaces. But FLW used the deep shadows to eliminate the exterior iridescence and added colour staining and patterning to break the transparency. Mies used the exterior mirror like gloss to reflect the changes occurring in the surroundings concurrently juxtaposing the interiors. This helped to reduce the massiveness of the built-form.


FLW Window with masking of Pattern > Flickr Image by Hardisty

Window glass is now often used to assimilate the realities of interior and exterior on a very large joint-less screen. The mix creates a very vivid object, like a water body reflecting both the sky and the floor. Metalized opaque glass belies the two-way transparency of a see-through element.

Wall to wall glass openings dissolve one or many sides of a volumetric space, reshaping its perceptive size, scale and extent. The spatial illusion becomes more intriguing when such a large reflective glass surface is used. Wall corners, large stretches of surfaces, acutely angled spaces, stubborn elements like columns and piers are dissolved by illusion of windows through mirroring effect of glass.


Corner in Glass > Flickr image by Wonderlane >

We are conditioned to expect certain spatial effects in a space. And glass is an effective tool for breaking that anticipation. A narrow space visually gets widened by a glass opening. Skylights and clerestories add ‘lightness’ to the space. Lights such as roof holes focus the attention. Openings, depending on their location and nature redefine the space configuration. The stratification of view to the outside offers different scale to the space. Significantly bright areas highlight the details, and so are perceived and registered, more effectively then darker zones. A window becomes an element for changing a space, intentionally and accidentally.


Madrid Crystal Glass palace Pixabay image by IvanPais Espanol


Madrid crystal glass palace > Pixabay image by IvanPais Espanol

Windows are furrowed gaps into an otherwise solid barricading mass. The depth is highlighted due to the dark interior, and shadows cast by strong and directional light. The shadows as a form creating element was very well exploited by L. Kahn in his Asian buildings. The same effect at a micro scale and in repetition creates a lattice, used in Indian Architecture. Windows like, bay, bow, Mashrabiya and oriel have been used to enlarge interior spaces and also to correct the interior shape of the space. Zarokhas add to the interior space but have also been used to undulate the exteriors.


Gothic window tracery Snettisham Norfolk England > Flickr Image by Spencer Means >

Masking has been very commonly used to change the character of the windows. Greek and Roman architecture subdued the openings as a secondary and less visible layer. Romanesque windows once again came to the surface, but openings were framed by the semi circular arch. Coordinating several windows was a difficult design issue, as the height of the rounded arch was defined by the width of the opening. Gothic architecture solved the problems of geometric composition, by of pointed arch. It also created a system of subdividing the window opening through mullions, transoms and glazing bars. The window opening was masked by traceried patterns. Window masking became an effective tool to overcome the deficiencies of glass, size, clarity and impurities. The deficiencies made the windows subservient entity of the load-bearing structure. Glass houses, orangeries, etc. allowed windows to define a space without the use of a wall. The need for very large and deep sun lit spaces for bus depots, railway stations, markets, and factories redefined the Windows’ spatial nature.


Pot Metal Glass stained Window Exhibit in Krannert Art Museum > Wikipedia Image

Framing is a property of all openings. Openings have their sides and mid members within the view cone depending on the point of observation. Palladio masked and framed the exterior face of the opening. The double-hung sash windows did the same on both, exterior and interior face. Framing is now used as an inevitable joint management system, and but often made imperceptible. Stratification (window openings’ position @ low, mid or higher level with reference to height of the user or the task plane) is an important ergonomic parameter that affects the spatial perception.


Elgin Cathedral > Wikipedia image by Billreid

Transparency is a quality of the glass, and the most important aspect of the surface of the opening. A window opening in the form of a glass curtain wall or shop front, shows up the space in its exterior surface configuration, and also the spatial depths of its interiors. The simultaneity of the exterior and interior spaces adds to the dilemma of the physical reality vs the virtual reality.


Glass house by Philip Johnson New Cannan, CT USA > Wikipedia image by Staib

This re-composed article is based on my earlier BLOG > here >

AND the BLOG was based on my Lecture Notes > Interior Components and Systems: Windows >>






Post    -by Gautam Shah



Looking out of Temple Door > Pixabay image by fr_golay

In all climates, geographic locations and cultures, a door is a major, preferred and often the only source of illumination, compared to a window or other openings. The degree of shutter being opened or closed provides easiest control over both the level and direction of illumination. Besides this, the door shutters, in the form of lattice, glazing, louvres, windowing, etc., provide more and easily maneuverable options for illumination control. The form and scale of the door such as tall, wide, large, small, flush or deep set, etc. offer other means of administering the illumination.


Control of illumination through a door is availed of:

1 by adjusting the size and form of the gap on opening the door shutter,

2 by providing lattice or glazing within the main shutter or by providing additional shutters for such options,

3 by increasing or decreasing the depth of the door and by shaping the sides of the opening (such as chamfer corners or splaying),

4 by defining the exterior and interior surroundings and base level near the door (the colour, texture, angle and distance of near by elements)

5 by selecting the orientation of the door opening,

6 by scheduling and siting of appropriate activities in or out of the door surroundings.


Flickr Image by David Masters

External Door

An external door of an enclosed space is very relevant for illumination and ventilation. The illumination is substantially determined by the Sky Component or SC, which checks the light reflected from the sky directly into a room. Any overhang or side projection reduces the sky component. The other major factor is the Externally Reflected Component or ERC, which depends on the quality of surface (texture), colour and reflectivity of the foreground of a door and other side areas (such as side walls). The third important factor is the Internally Reflected Component or IRC. It consists of light reflected from the internal surfaces of the room. Adjustment of IRC is very helpful in controlling the glare through the open door (Glare is the high difference of light between the opening and its surrounding surfaces).


Doors at the back of INFOSYS Institute, Mysore, India > Wikipedia image by Prateek Karandikar

The Internal Door is not very useful for illumination, unless the other side of the interior door (of room, passage, etc.) can contribute some reflected illumination. Such ‘borrowed’ illumination may be sufficient for ‘passive’ activities or ‘less-used’ areas like stairs, passageways, etc. However, in very warm climates and coastal areas like the Mediterranean or Kerala, where external brightness is very high, an external door brings in radiant heat along with light. This is controlled by placing doors in verandahs or with deep awnings. Doors with louvres are widely used in Mediterranean climates to reduce the brightness and glare. Deep-set doors are also created by placing doors on the inner edge of a thick wall (where possible) or by creating deep portals.


The ruined Tyn Llan viewed through open door of the Llantrisant old church > source:> Author: Eric Jones

Illumination has a direct bearing on the door orientation. The main doors of early Egyptian buildings were East facing and the Sun god was revered. The East and West have been prime directions for illumination in many historic places of worship. With the ascent of the clear storey openings or entire glass curtain walls the importance of a door as the chief illumination element has reduced.

Illumination and the size of a door have a direct relationship. A taller door is more effective then a wider door in illuminating deep interiors. Monumental buildings have tall doors not just for architectural grandeur but its was the upper section of a tall door provided the deep illumination during a crowded ceremonial function. In Egyptian temples the upper section of the door was supposed to bring in the Sun god with the first rays of rising sun. The tall door was unmanageable for shutter mechanisms and useless as a passage. The upper section was either left without a shutter or latticed to form a ‘transom’. It was more practicable to leave a transom or a rose window than load a wall over the door lintel.

The illumination through a door has also been enhanced by providing side lites or side-lights and within the door lattices. Panel doors of Greek buildings were partly latticed in the upper sections, or had additional latticed shutters. Side lights or side windows increase the perceptive width of the opening, decrease the size of the shutter and reduce the structural span of the lintel.



WINDOW LOCATION: A window with an interior wall at a right angle distributes the light well, reducing the glare, compared to a centric window that causes contrast and so glare. A window in a wall with interior colour of lighter shade seems less contrasting than a window in a dark coloured wall. Chamfered or splayed sides of the window opening over the inner edges creates planes of intermediate brightness and thereby dispersion of illumination. Similar chamfering of the outer edges enlarges the sky component and thereby greater intake of illumination. A chamfered sill illuminates sections close to the wall. Windows located high in a wall or in the roof trusses and clerestories result in deeper penetration of light and better distribution. A rule-of-thumb is that the depth of daylight penetration is about two and one-half times the distance between the top of a window and the sill. Light-coloured floors allow daylight reflection to the ceiling section.

Brightness is a perceived phenomena or a subjective attribute of light, because the sensitivity of the eye decreases as the magnitude of the light increases. It cannot be measured, but checked as between very dim and very bright (brilliant). If the luminance of a viewed light source is increased 10 times, viewers do not judge that the brightness has increased 10 times. The relationship is, in fact, logarithmic: the sensitivity of the eye decreases rapidly as the luminance of the source increases. It is this characteristic that allows the human eye to operate over such an extremely wide range of light levels.

MODELLING: For a designer ‘modelling’ of objects is as important as their functional aspects are. Opening systems like windows, skylights, clerestories provide the necessary natural luminance (brightness or intensity) to show the form, colour and texture of objects. Objects are perceived mainly due to the direction of light and its ever-changing nature. These are often enhanced, contrasted or subdued by reflectance and also by artificial illumination. Corbusier has used planes strategically placed against openings to model the interior spaces. The size and intensity of the luminance determine the shadow density and so affect the ‘modelling’.

For visual effectiveness, some contrast in brightness levels is desirable in a space. Dull uniformity in lighting leads to tiredness and lack of attention. Windows on multiple orientations and height levels must be combined to produce the right mix of light for interiors.

Light from a single bright source over emphasizes the shadows and textures, and therefore creates a model that may be all right only from certain points of observation. Light from a large diffuse source softens the texture and dulls the neat delineation of the object (modelling), but permits mobile objects to be seen. Light from multiple directions and if in different intensities accentuates differences between different planes of the object. However, a very large diffuse source eliminates the texture. Light which comes from a large top source like a roof, seems shadow-less and so featureless, compared to light from a side, which enhances the horizontal dimension and creates a definition.