BRIGHTNESS and COLOUR

Post 712 -by Gautam Shah

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Brightness and Colour have mutual dependence. Greater brightness leads to sharper visual perception and the colour (spectrum) affects the perceived level of brightness. Physiological and environmental conditions alter the perception of brightness as well as colours. Noon time daylight conditions are accepted as the optimal brightness condition for experiencing the colour. But this condition of high brightness can reduce the contrast between two near by objects and so confuse the colour perception.

Brightness and colour, both are strongly affected by the immediate past experience. Sudden transition from darkness to brightness or one colour to another affects the pupil dilation.

Brightness and colour relate to reflection from a surface. The quality of a surface, the texture and its grain orientation vis a vis the directions of illumination and observation, affect the perception. Most of the objects reveal their multiple surfaces concurrently but brightness and colour on each of the face seems different. In this scenario the source of illumination (if solar) and observers both vary their position. As a result colour perception is very dynamic phenomenon. In Architecture or Interior design colour matching or determination of brightness is always worrisome affair.

Next factor is the context in which objects or scenes are observed. The juxtaposition with a lighter background enhances and darker backdrop setting dulls the perception of brightness and colour.

Colour perception operates at three basic levels, as the capacity of a surface to reflect light, as emission of light from a hot body and the personal capacity to differentiate various colourations. But the conveyance of the ‘colour related experiences’ is even more difficult. The interpretation of colours varies in different setting of locations, cultures and circumstances. Environment and Terrain are two major factors that alter the colour. Environmental conditions like solar brightness, inclination, orientation, cloud-cast conditions, atmospheric refractions, etc. vary depending on the geographic location. These are further attuned by the surface extent, texture, angle and duration of exposure. The terrain offers very pervasive colour context against which everything is observed. The different terrain effects are really not perceived on the site, but experienced through time-space segmented documents like photographs, paintings, videos or movies.

The conditions at ground level such as surface colour, wetness, snow, vegetation cover, topography, orientation, man-made and natural features, surroundings, density, reflection (albedo), absorption, altitudes etc. determine the colour quality of light. Since all these surface conditions are very localized, the colour variations are conditioned by them. The buildings in surrounding areas, immediate terrain and water bodies have a bearing on the quality of illumination entering a building.

Illumination in a space is Natural (daylight, chiefly solar origin), Artificial and often combination of both. Daylight has Four important facets, the illuminance, warmth, colour and the variability. Daylight on an outdoor location is a combination of direct sunlight, diffuse sky radiation, and both of these as reflected from the earth and other objects. The brightness and colour of daylight are governed by the sky conditions, like clouds, fog, smoke, atmospheric pollution, morning and evening twilight zones (when the atmospheric scattering of predawn sunlight takes place).

The solar radiation as received on the surface of Earth varies from place to place, season to season, day to day and even hour to hour. Equatorial regions receive more radiation, than polar regions. Darker surfaces, like the tropical forests reflect very little radiation, 10 %, compared to snow bound high latitude areas, which nearly reflect 80 % of the energy received. Cloudy and dust polluted areas receive less solar energy. Direct sunlight at noon can have illuminance as high as 120,000 lux (Compared to this moon light is <1 lux). Sunlight is a warm colour light, at noon, the colour-temperatures are about 5500°k, bluish-white or ‘cool colours’ and at sunset, these are about 2700-3000°k (degrees kelvin), are yellowish-white through red or called ‘warm colours’.

The reflected light from the exterior surfaces of buildings, roads and pavements affect the illumination on lower floors of the buildings. These cause minor variations due to movements of people, vehicles, ripples on water bodies and leaves of trees. Upper floors of tall buildings, except in similar localities, receive fairly consistent, but very strong daylight from nominal windows. Such floors with low or no sill windows (glass curtain walls) get varying levels of illumination, often strongly coloured.

Reflectance of rooms’ interior surfaces impacts the perception of brightness and colours in a space. The surface reflectance is a function of colour, its texture (matt, dull-sheen, glossy) and the orientation of grains of textures. Extreme levels of brightness, if, are present within the same field of view, can be calibrated by the surface texture and colour. Historic buildings, sites and remains, are conserved with surroundings updated through paved stones of same colour-texture as the original built-form or green lawns. These choices, alter the degree of interior brightness, as well the quality of colour.

Similarly cities conserved with enforced thematic colours (blue -Jodhpur, Pink -Jaipur, both in India, white -Santorini, sienna browns -Italian, Piazza del Campo and ), create monotonous colour tonality in interior spaces.

For artificial illumination sources Brightness and Colour have some sensorial connection. Artificial light sources one commonly accepted rating, the Colour rendering index (CRI). It is supposed to index ‘how the colour will look’. High CRI (nearly equal to daylight in afternoon) will mean colour will look ‘real and right’ and low CRI will mean unreal (weird) and wrong. CRI has limited relevance, if only the illumination source is white (Candles and incandescent bulbs can have high CRI ,but are off-white. The sodium lamps have low CRI but high brightness.

 

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EXTERNAL or INTERNAL ‘REVEALS’ of OPENINGS

Post 685 –by Gautam Shah

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Walls are chiefly load bearing entities. The thickness is the third dimension to the nominal planner structure. The third dimension has a functional depth, and architectural character. The Architectural expression of the wall-depth modulates the facade and gives a massing flavour. The functional depth frames the view, and regulates the illumination in the interior space.

Openings in thicker walls have external or internal ‘reveals’ surrounding the frame. The bottom section forms the ledge of the sill. Openings placed on the outer face create deep an inner side or intrados (originally intrados meant, the inner curve of an arch or vault). Similarly openings placed on the inner edge form exterior side or extrados (originally extrados meant, the outer curve of an arch or vault).

The deep interior sides, if ‘square-edged’ (at a right angle to plane of the window), made the perceived size of the opening smaller, then it actually is. This type of setting on interior sides, was not a major issue, where the room spaces were comparatively narrow, and so reflection from opposite walls was available. The narrow spaces were due to the technological restrictions and for functional requirements, such as in long halls and church buildings. In squared buildings the illumination was balanced from windows in the drum perimeter of the dome.

The deep exterior sides, if ‘square-edged’ (at a right angle to plane of the window), made the perceived size of the opening smaller, a desired arrangement to enhance the wall area and de-emphasize the presence of gaps of openings. It reduced the ingress of winds and snow-rainwater. To emphasize the presence of gaps, portals were added as the opening’s treatments.

The ‘square’ edged openings have high contrasting brightness. Such windows require counter illumination to reduce the glare. To distribute the light better in the interior space, inner sides (-intrados with the window fixed on the outer edge) and an outer side (-extrados with the window fixed on the inner edge) were splayed by chamferring. The angled side surface was further carved, fluted with ornate borders or architraves.

Inner vertical sides, window heads and the sill, all were sloped to enlarge the reflective surface area. The chamferred sides on the outer face allowed more light by increasing the sky component, and allowed wider view of the outside.

The effects of square and the chamferred sides of openings were well known to the mural artists (working with different mediums such as tempera, mosaic and frescoes painting), who accordingly composed the stories, shading in the scene, perspective angle, colour’s  hue and tone of artwork.

In Romanesque and early Gothic architecture the windows were fixed on inner face, creating a plain and undisturbed interior surface. But by the time this was perfected, the Gothic walls were completely diminished, and windows were as wide as the gap between two columns.

Side walls of Gothic buildings became thinner due to the arrangement of flying buttresses and use of load-bearing columns. But the same advantage was not available in case of un-buttressed Front wall. The entrance doors of Gothic churches were flush-set on the inner face, and that allowed better view across and fuller distribution of light. But the doors set deep in the thick walls, needed chamferring with serrated sides.

In Baroque architecture the depth of opening was concealed with the projected facade elements like columns, pilasters, cornices, or pediments. In Italian Renaissance the facade had an applique lattice like a pattern that united several openings. In post medieval period, windows began to protrude out of the buildings, over into the narrow street. Bay and oriel windows, Mashrabiya openings in the middle East, and Zarokhas in India transgressed out, mainly to gain sideways view and air. The multi sided mass of the projection became a personal statement.

In post medieval period, window projections created serious fire hazards and issues of encroachment of public lands. Both of these were corrected through improved fire laws and defined easement rights. Fire laws required windows to be within the wall (without any projections like ledges or hanging shutters). Later the Window tax curtailed the number of openings in a building.

Gothic architecture had already shown how to divide large openings with traceries of mullions and muntins. Large windows in thin walls require framing and masking, but small depth did not allow formation of integrated architectonic elements, or scooping out for niche creation. Architectural add-on elements such as half columns, extrados, porticoes, etc. were additives placed to frame and highlight the opening.

The surface of the window was strongly stated by articulated divisions, contrasts between glazed and other surfaces like rusticated masonry. Windows were also placed in inward or sunken bays. The mid-wall between the windows was treated as very shallow niche or bordered frame for murals, paintings or placing a fireplace or library cabinet. Building’s facades of thin walls were also undulated by outward bay windows, ledges and other projections.

Thick walls accommodate the shutters of doors and windows within the gap. But shallow window gaps offer no shading. Some form of external shading system is required. Such shading systems have been used for creating architectural facade system, as in Chandigarh Secretariat building.

Glass curtain walls are thin body construction, often without any projections for solar protection. This now sought through the glass technology, and the ventilation through separate HVAC system. Thin walls save floor space, and so are economic in spite of the compulsory recourse to other compensatory facilities. The nominal architectural play of depth and shadows for 3^rd dimensional visual depth is not available with openings in very thin walls. This is now recreated by volumetric play of the building mass, or by variegated surface finishes. For such surface modulation, other means include visual reflectance and glows (illumination from within).

The vividness of stained glass windows or the colourful lanterns of Gothic eras are now recreated through see through LED glass. At another level the touch screen provides the same fare. The mix of the two will become part of architectural and interior face of buildings.

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PERCEPTION of CONTRAST -Issues for design -18

Post 659 -by Gautam Shah

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Contrast is a deviation from the expected. It is the realization of a thing against, the obvious, existing, notional or ideological percept. Contrast is seen between nominal or obvious things, versus abnormal or non-perceived conditions. Like a full vs empty streets, clear vs fuzzy, pleasant smell vs unpalatable taste, dark-hot vs bright-cool, vibrating but noiseless; These are some such expectations vs perceptions.

Contrast is a comparison and occurs in some reference. The reference forming nexus is proffered in real or a hyper realm. But the ‘thing’ and its context are not always in the same space or time setting. Contrast makes a ‘thing’ stronger by juxtaposition of some weaker, duller or different elements.

Contrast is detected by two distinctive processes. The perception, is a combined experience of different sensorial faculties. And it is also a process of cognition that defines the strongest experience forming the main object or foreground, and all other as the background. The backgrounds offer the context.

Sensorial faculties have their own scale of strength, and some have bipolarity. Typically eyes and ears continuously back up the space-position details. Similarly nose and tastes buds in the mouth, are closely located, and so show time-simultaneity in definition of edible things. The space-time references are filled in by other senses. Multilateral nodes of touch support such a process.

The foreground-background divergence manifests in time-space reference. The juxtaposition, however, is not in the same space or time setting. The nexus could be in real or hyper a real realm. The hyper realm consists of experiences and resulting expectations. One has seen neither heaven nor hell, but both pose concurrently as extreme contrast. One of the two could be real and other through anecdotical knowledge. Here the contrasts are realized through recall. The contrast is relevant till foreground-background simultaneity remains within a fathomable range of perception. Architectural entities contrast in size, scale, style, placement, orientation, and environmental conditions, thematic content etc.

The contrast offers a scale. Objects forming the contrasting zones have shapes, extent, proportion, and indicate a direction. The depth is the obvious phenomenon of foreground-background differentiation. Other two dimensions of the scale are formed by the shape and its extent. The fourth dimension of reality occurs with vivid scenes. Here, if the background is dull or static, the foreground contrasts intensely. And, where the foreground is dull or rapidly varying, the particulars of things and happenings fail to register effectively. The perceiver becomes confused and disinterested, if ‘back and foreground’ elements fail to present relationships in terms of now-then, here-there, far-near etc. In Design, there is always a conflict between context and contrast, requiring equilibrium.

Contrast makes things conspicuous to attract the senses. And the contrast to be obvious, occurs with some reference. The reference is formed by a ‘thing’ that is stronger by juxtaposition of some weaker, duller or different elements, by its power of persistence in reality, and as a recall. Often clues are included in the composition for the recall. The clues could be similarities, leftover trails of the past happenings or subtle insertions relevant only to the person experiencing it or in that time and space. Other design elements that offer contrast include presence of directions, sequences, repetitions, occlusion by frames, thematic continuities, sensorial consistencies, associated fables and explanations.

A design has internal and external context. Internal contrasts are part of the designed entity, so within the ambit of real experience. External contrasts occur through the embedded or implied metaphoric clues for connection.

Architecture occurs in the context of its terrain, environment and stake holders (humans and tasks) and incorporeal parameters like weather, culture, economics, social and politics. These are universal posers, some find them suffocating in creation of outstanding and long-lasting contrast. So contrast is realized by negation of the contextual elements. Architects resort to attitudes like deconstructivist, monumentalist, eccentricist etc. Architecture has been for a very long time and substantially static formation, but now for evocation of contrast, not only the form is made dynamic but the perceiver-users are made mobile and hyperactive. These experiences began in rapidly changing environmental conditions, unsettled positions of perceptions, gyrating conditions, gravity less conditions, videos and movies.

In art work like paintings aberrations of perception arise from how spaces are postulated by extent and depth, and time is suggested with metaphoric details. The way colours are seen or weights are felt is due to such contrasts. Our past experience and desires make us see or experience things before they happen at closer locations.

A silhouette is a very specific condition of contrast. Here the proportion of dark-light is of course important, but the edge conditions like shapes, arrangement, sizes etc. determine the effectiveness of contrast. Silhouette work in two ways: One due to the stark difference between the background and foreground, and Two due the lack of details in the foreground object. A glare is a form extreme contrast which fuzzes the foreground.

Camouflage is in a way opposite of contrast. It forms from the skillful exploitation of the contrast, though the resultant scenario is cacophonous. The noise occurs from anomalous conditions between the perception and its cognition. It is also the difference between real experience and the expectations. Camouflage morphs the foreground with background, alternatively the foreground turns fuzzy due to the reflections, multiple impressions, askew positioning, colour intonation, altered scaling etc.

Contrast occurs due to cascade of light, glare, echoes or reverberation, masking (of smell, taste), screening, covering, hiding reflections, and framing.

This is the 18 th article of 20 topics series on ISSUES for DESIGN

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BLOGS LINKS about PERCEPTION

Post 652 -by Gautam Shah

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These are my select few 91+ blogs (out of nearly 850 placed on my 4 blog sites) written over last 4 years, now compiled under a common theme ‘Space Perception’ with following sub sections.

      0  New series of Lectures (Four) on Perception

1. SPACE PERCEPTION
2. ILLUMINATION
3. MOVEMENT, BALANCE
4. OPENINGS SYSTEMS
5. GLASS
6. GRILLS, TRELLIS, CURTAINS
7. SOUND and NON VISUAL
8. OBJECTS, SURFACES, COLOURS, PATTERNS
9. REALITY, MAKE-BELIEVE

 

0  New series of Lectures (Four) on Perception

0.1 SOME SOUND BITES -Space Perception -I

https://designacademics.wordpress.com/2018/02/12/some-sound-bites-space-perception-i/

0.2 STRATIFICATION of VISION

https://designacademics.wordpress.com/2018/03/02/stratification-of-vision0.2 /

0.3 PERCEPTION of SPATIAL FIELDS -ILLUMINATION

https://designacademics.wordpress.com/2018/03/11/perception-of-spatial-fields-illumination/

0.4 MULTI NODAL PERCEPTIONS of OBJECTS in SPACE

https://designacademics.wordpress.com/2018/05/14/multi-nodal-perceptions-of-objects-in-space/

 

 

1 SPACE PERCEPTION

1.1 PROCESS of PERCEPTION

1.2 PROCESS of PERCEPTION part-I

1.3 SPACE PERCEPTION -through seeing, hearing and touching

1.4 SPACE PERCEPTION – Issues for Design -4

1.5 SPACE PERCEPTION

1.6 SPATIAL DEFINITIONS

1.7 SENSING OBJECTS BEYOND THEIR SIZE MEASURES

1.8 SPATIAL DEFINITIONS

1.9 SPATIAL DISTANCING and BEHAVIOUR

1.10 DISTANCING in SPACE

1.11 SPACES SIZES and SHAPES

1.12 SMALL SPACES and LARGE SPACES

1.13 REACH in SPACE

2 ILLUMINATION

2.1 CONTRAST EFFECT – PERCEPTION

2.2 PERCEPTION of SPATIAL FIELDS -ILLUMINATION

2.3 DAYLIGHTING

2.4 DAY-LIGHTING – in Interior Spaces

2.5 DESIGN CONSIDERATIONS for DAYLIGHTING

2.6 SPACE PERCEPTION and ILLUMINATION

2.7 DAYTIME INTERIOR ILLUMINATION -REALITY and PERCEPTION

2.8 INTERIOR ILLUMINATION through DOORS

2.9 WINDOW LOCATION and NATURAL LIGHTING

2.10 LE CORBUSIER and ILLUMINATION

2.11 COMPARING WINDOWS of FLW, LC and Mies

3 MOVEMENT, BALANCE

3.1 MOVEMENT and BALANCE – Issues for Design -5

3.2 PERCEPTION of BALANCE and MOVEMENT

3.3 BALANCE in DESIGN – Part 1

3.4 BALANCE in DESIGN – Part 2

3.5 VISUAL PERCEPTION of MOVEMENTS

3.6 PERCEPTION through SCALES and CONVERSIONS -Issues or Design -3 

4 OPENINGS SYSTEMS

4.1 LEVELS of OPENINGS

4.2 DESIGNING OPENINGS

4.3 CLASSICAL WINDOW FORMS

4.4 ARCHITECTURAL WINDOWS and VISION in-out

4.5 ARCHITECTURAL WINDOWS and the MEANING

4.6 ARCHITECTURAL WINDOWS and MECHANICS of VISION

4.7 MEANING of a WINDOW SILL

4.8 THIRD DIMENSION of OPENINGS

4.9 LANTERNS in ARCHITECTURE

4.10 CLERESTORY OPENINGS

4.11 SKY LIGHTS

4.12 ROOF LIGHTS

4.13 SHOP WINDOWS

4.14 SHOP WINDOWS – SHOP FRONTS – DISPLAY WINDOWS

4.15 FRAMING of OPENINGS

4.16 MASKING of OPENINGS Part -III -Framing

4.17 MASKING of OPENINGS Part -II

4.18 MASKING of OPENINGS Part -I

5 GLASS

5.1 GLASS in ARCHITECTURE -1

5.2 GLASS and PERCEPTION

5.3 GLASS in WINDOWS – Part • I

5.4 GLASS in WINDOWS – Part • II

5.5 COLOURED GLASS

6 GRILLS, TRELLIS, CURTAINS

6.1 CONTEXT -Issues for Design -12

6.2 ROOFS 3 -Skyline and Silhouette

6.3 HOLISM and DESIGN

6.4 TRELLIS

6.5 GRILLS

6.6 CURTAINS

6.7 TRANSLUCENCY for CURTAINS

6.8 SHEER FABRICS and CURTAINS

6.9 SHEER FABRICS and CURTAINS-2

6.10 NON SILK SHEER FABRICS and CURTAINS

6.11 WEIGHT and TRANSLUCENCY of fabrics for curtains

6.12 SHEER FABRICS

7 SOUND and NON VISUAL

7.1 SOUND

7.2 SOUND, SPACE and PERCEPTION

7.3 PERCEPTION of SOUND and SPACES

7.4 SPACE and SOUND REVERBERATION

7.5 SOUND and NOISE MANAGEMENT

7.6 HEARING and interior spaces

7.7 ACOUSTICS in SMALL SPACES

7.8 SOUND and SMALL SPACES

7.9 SPACE PLANNING and NON VISUAL CUES

7.10 NON VISUAL LANGUAGE -Issues for Design -6

7.11 LANGUAGE EXPRESSION and SOUND PERCEPTION

8 OBJECTS, SURFACES, COLOURS, PATTERNS

8.1 OBJECTS in SPATIAL FIELDS -Issues for Design -14

8.2 COLOURS -Perception and Expression

8.3 COLOURS and BUILDINGS

8.4 FLOORINGS

8.5 FLOORING COLOUR

8.6 FLOORINGS IN INTERIOR SPACES

8.7 PERCEPTION of SURFACE FINISHES

8.8 GLOSS

8.9 TEXTURES and MATERIALS

8.10 JOINTS in SURFACE FINISHES

8.11 MOSAICS

9 REALITY, MAKE-BELIEVE

9.1 SOLIDS and VOIDS -issues for Design -13

9.2 AUGMENTED REALITY

9.3 SPACES and REALITY

9.4 MAKE-BELIEVE in INTERIOR DESIGN

 

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SPATIAL NATURE of WINDOWS

Post 644 –by Gautam Shah

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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.

Elbe Philharmonic Hall Hamburg Plaza Germany > http://maxpixel.freegreatpicture.com/Germany-Elbe-Philharmonic-Hall-Hamburg-Plaza-2000436

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 > https://flickr.com/photos/bpprice/12043141995

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.

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.

Reflection in Windows > http://maxpixel.freegreatpicture.com/Reflection-Building-Architecture-Window-Glass-922529

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.

https://www.pexels.com/photo/architecture-building-business-city-245618/

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 > https://www.flickr.com/photos/wonderlane/4889566212

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 > https://flickr.com/photos/hunky_punk/7511302668

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 >

http://talking-interior-design.blogspot.in/2009/12/spatial-character-of-windows.html

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

http://www.gautamshah.in

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DESIGN CONSIDERATIONS for DAYLIGHTING

Post 593 –by Gautam Shah

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Daylighting is illuminating the interiors of built spaces with the sunlight, as available during the sun up period. This is controlled entry of natural light and diffuse skylight into a building to reduce electric lighting and saving energy. The ‘direct’ daylight arrives through openings like doors, windows, skylights and other gaps. ‘Indirect daylight’ is brought in as Diffused sky light from surface reflectors or Transmitted light through tubes and other devices.

Haveli Courtyard, Near begum Samru’s palace > Flickr image by Varun Shiv Kapur

Daylighting depends on the external conditions, such as the season of the year, climate, dust, fog or cloud cover, time of the day, terrain or surroundings. Daylight can be designed through buildings, size (spread or massing, depth, floor heights), form or shape, orientation, scheduling and location of tasks, configurations of openings, etc. It is closely linked to saving energy used for lighting during daytime. Daylight is substantially dependent on openings like doors and windows, and this help creates stimulating and natural environment.

Chhatrapati Shivaji International Airport Mumbai Departure area > Wikipedia image by Nancy Beaton

■ Daylighting is dependent on external conditions. The season of the year determines not only the ‘sunshine’ days and brightness, but the direction (solar inclination) of the light. The climatic conditions govern if fenestrations can be kept fully open or closed. Local atmospheric conditions like dust, fog, cloud cover and pollution affect the intensity of daylight. Activities must be scheduled according to the diurnal cycle and positioned as per the available exposure. The surroundings’ factors, such as the terrain slopes, colour (of white sand beach fronts, green lawns or foliage, water bodies), and reflective capacities determine the brightness level of illumination.

Sahara Town Ghadames Libya > Wikipedia image by Luca Galuzzi http://www.galuzzi.it

■ Daylighting and building design, have mutual dependence. The exposure of the face, surface area, perimeter and form of the buildings can be advantageously exploited for better gain of daylight.

■ Daylighting for energy saving must be conceived with a view to reduce the artificial illumination requirements of deep-set spaces, low height spaces, isolated interior entities like vestibules and corridors. A synergetic system to calibrate the electric illumination can be created for task-need and occupancy of the space, compensative distribution (elimination of glare-contrasts) and low heat output.

High sill windows Abbaye d’Acey Jura France > Wikipedia image by Arnaud 25

■ Fenestrations and Daylighting are linked. Fenestration location (wall, skylights), height, shape and construction affect the daylighting. Fenestrations also serve the purpose of comfort (ventilation requirements such as heat gain-loss, air-moisture control, interior pollutant dilution, air movements) and view in-out, so must incorporate these requirements.

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Daylight used for illuminating interior spaces, exploits the ever-changing quality in terms of intensity, colour and direction of the light. The daylight-design, scatters the light over a wider extent, diffuses its intensity and subdues the strong directionality, alters the colour quality, and shifts the location of the source.

Screening for daylight and view Wikipedia image by Margaret Bourke-White

● Light intensity is a function of season, orientation and fenestration design. These are important considerations for siting an activity. Light intensity is perceived against the brightness level of the background scene or the surfaces. It can also be altered by illumination from other directions or additional artificial sources.

Tony Rich Training Centre Uni of Essex Consistent illumination by skylight and support by electric light> Wikipedia image by Rwendland

● Colour of the daylight as reflected sky component have small colour variations, except the occasional colour scattering at sun rise and set periods. Daylight received from reflected surfaces such as terrain, near by buildings and plants has a colour tinge. The colour of the glazing material, colour of the opening cover systems like Venetian blinds, curtains, overlay films, etc. side-surfaces of fenestration systems.

Colours of the surroundings > Flickr image by Darron Birgenheier

● Direction of the light is an important consideration for ingress or avoidance direct sunlight. North light (South light in S-hemisphere), are designed to access best natural illumination for industrial plants. East side facing openings allow ‘cool’ brightness in comparison to West faces.

Darker surface does not equalize the light > Pixabay image

● Scattering the light over a wider area achieves equal brightness by avoiding high-low contrast or patchy areas. This is done by multiple openings or by masking the opening with diffuser screens. Scattering is avoided where dramatic effects are intentionally created such as vestibules, entrance halls, etc. Equalization of illumination in space is also achieved by electronic sensors that activate electric illumination in required intensity.

Taliesin West drafting studio illumination > Wikipedia image by Steven C. Price

● Diffusing the intensity of light is resorted to reduce the high level of brightness on summer or clear sky afternoon periods. This is done by automatic masking devices or by baffles or louvers with apertures attuned to non-bright exposure-directions and schedules. Diffusers are also used to reduce the level of brightness in areas that act as transition spaces to darker environments such as auditoriums.

Strong light source and contrast > Pixabay image (of woman by window)

● Calibrating a strong sense directionality with illumination is necessary to reduce the dynamism of direct natural illumination. Architectural openings like doors and windows bring in variations of brightness (movement of clouds), shadows of moving objects (trees, vehicles, other traffic), and variations of colours into the interior spaces. This changeability is often an irritant for work areas like laboratories, libraries, bedrooms, etc. By sourcing the daylight from multiple directions, the illumination can be made static and multilateral.

Contrast reduced by additional illumination from side openings >Window at the East end of Choir in Month of Feb, Wells Cathedral Somerset > Wikipedia image by IDS.photos from Tiverton, UK

● Altering the colour quality where colour perception is important such as in surgical and pathological areas of hospitals, colour and dye manufacturing plants, film and media editing rooms. Here not only the colour must be neutral but consistent. This is achieved by avoiding light reflected from external sources, such as pavings, walls and lawn or green foliage.

● Shift the location of the source is important for space planning design at micro level. The available natural source may have strong left or right, up or down delineation and may need the shift of illumination location. This is done by external and internal reflecting surfaces or use of light transmission tubes.

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DAYTIME INTERIOR ILLUMINATION -REALITY and PERCEPTION

Post 486  by Gautam Shah

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Illumination is required in interior spaces in several contexts. At realistic level, task illumination is the most obvious requirement, but one needs sufficient illumination to move around known as well as unknown interior spaces. At perceptual level an illuminated space is associated with cleaner and healthier space. The perception has been so ingrained into our psyche that interior brightness and well-being of the space as one concept. For ages, in absence of glass, openings were ‘open’, allowing sufficient ventilation through the cracks and gaps in the door or windows. And even when openings began to be glazed, the sunlight seeping through it warmed up the interior space to cause air movements, and act as bactericide.

 

In Northern hemisphere, the North, and in Southern hemisphere the South, gets solar exposure throughout the day. And so, at realistic level, the North and South facing openings are chosen for illumination in factories, schools and homes. But perceptively, it is the East, than west, or combination of both, have found favour, for religious buildings. East-west light is nearly horizontal in the morning-evening and penetrates deepest section of a building. It is varying hour by hour, unlike the consistent North-South light. East-West light is dynamic and awe inspiring. In early Egypt the Sun god was revered and the main doors of temples were East facing. North and South doors have high inclination of the sun, so horizontal penetration of illumination is not very deep.

West front of Wells Cathedral UK

Door orientation has a direct bearing on the level of illumination. Early Church buildings had Eastern entrances to illuminate the altar from front, but an altar with an Eastern back-lit glass windows proved to be a better alternative. Gradually churches began to have Western entrance doors. The East-West have been prime directions for illumination in many historical buildings, however, with the ascent of the clear storey openings the importance of a door as the chief illumination provider has decreased.

The size and Width-Height proportions of a door have a direct relationship with the depth of illumination. 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 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 doors were unmanageable for shutter mechanisms and also too narrow for ceremonial 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 sidelight and also ‘within the door’ with lattices. Greek buildings had panelled doors that were partly latticed in the upper sections, or had additional latticed shutters. Side lights or side windows decrease the size of the shutter and reduce the structural span of the lintel, but increase the perceptive width of the opening.

Illumination through a door invariably accompanies the radiation. The solar radiation through a door varies depending on the geographical location, orientation, time of the day, shading devices, nature of the foreground and surroundings, etc.

Puerta del Perdón, Catedral de Toledo, España Pic by Sevillista on Flickr

The depth of the door (depth of the wall) defines the quality of illumination. A door in a very thin wall (Gothic architecture) -the flush set door, allows fuller distribution of light, (a larger segment of brightness on the inside), but a deep-set door curtails the brightness due to the sides of the wall. In Gothic cathedrals due to side buttressing the side walls were thin and allowed flush set openings (with stained glass), but the same structural advantage was not available in case of un-buttressed front walls. The entrance doors of Gothic churches were deep set in thick walls but with serrated edges. Door sides (i.e. wall sides) and heads have been chamfers cut, on inside or outside faces, to enhance width and height. Chamfered edges on outside make the opening flush on the inside wall, and allow wider perception of the outdoors. A bevelled edge on the inside, make the opening flush on the outer edge of the wall. It allows visually more perceptible brightness on an interior surface due to the additional lit surface of the bevelled faces.

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DAY-LIGHTING – in Interior Spaces

Post 366 – by Gautam Shah

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Day-lighting or daytime natural illumination is an important requirement for Interior spaces. The illumination requirements vary for various tasks, background brightness (contrast or glare), forms of shadows, and movement or variations in levels of lighting. The direct sources of daytime natural illumination in interior space are openings like doors, windows, gaps, cracks, punctures, translucent or transparent walls, trellis, etc. Besides these there are number of indirect means that enhance or contrast the direct sources of illumination. These means are planer or curvilinear surfaces, reflective surfaces, colours and textures. The daytime illumination arrives to a built-form, from different directions and sources, such as directly from the source, from sky, and as the reflections from terrestrial objects. These sources include, direct sunlight, diffused sky radiation, and both of these as reflected from the terrestrial objects.

The amount of daylight received into an interior space is defined as a daylight factor (being the ratio between the measured external and internal light levels). The external light level can be as high as 120,000 lux at noon for direct sunlight at noon, to less than 5 lux on very heavily cloudy evening.

To gain maximum daylight into an interior space the building should have wider foot print and its perimeter should be linear or undulated. The building must be longer in North-South direction, compared to East-West direction, unless the space is meant exclusively for either Morning or Evening use. For Northern Hemisphere, North side and for Southern Hemisphere, the South side receives more daylight.

The neighbourhood buildings and topography and immediate surroundings have a bearing on the quality of illumination entering a building. The reflected light from surfaces of buildings, colours of roads and pavements affect lower floors of the buildings. Reflections from sea front and movement of trees tops, due to the breeze, can have unsettling effect on interior spaces. Upper floors of tall buildings, except in similar localities, receive consistent, but very strong daylight from nominal windows. Such floors with bottom windows get disturbing reflections from traffic and other movements, reflected to the ceiling.

Location of openings, their proportion to wall, and distribution, determine the distribution of day light in the interior space. In tropical climate zones and in colder climes during warmer months, open doors play a very important role in daylight gain. Similarly, open to sky Chowk or cutouts with surrounding passages or ‘livan’ like spaces allow distributed illumination.

For good day lighting the interior spaces must have at least one face with exterior exposure, or with an abutting shading component like verandah or gallery. A skylight or upper level opening is an efficient source for natural illumination. A taller window leads the daylight deeper into the room space. The depth of daylight penetration is approximately two and one-half times the height of the opening.

High – performance glazing with downward inclination

The space planning of an interior layout must be optimized for daylight. Large tall pieces of furniture can act as mid space barricading element or as reflective surfaces. In commercial spaces half or fully glazed partitions can allow just sufficient illumination for passage areas. A plain ceiling at low level may not be as reflective as a stepped or contoured one.

On exterior and interior sides use of light-shelves, against an opening, helps distribute the daylight and cut glare. A light shelf could be a small width blade of a louver to very large fixed or adjustable jalousie system. A high-performance glazing systems generally admit light without the heat gain.

Reflectance of room surfaces impacts the perception of brightness in a space. The surface reflectance is a function of colour, its texture (matt, dull-sheen, glossy) and the orientation of grains of textures. Extreme levels of brightness are present in the same field of view, can be calibrated by surface design.

Daylight must be planned and ‘attuned’ for requirements of tasks, posture, communication, expression and intra-personal relationships, Poor visibility, recognition, and discomfort result from lack of required levels of illumination, direction. To remove wearisome consistency (as with sky or high level openings), some variations in moment to moment daylight must occur.

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WINDOWS and VENTILATION

Post 280 – by Gautam Shah

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Windows served two main functions for interior spaces: Ventilation and Illumination. To this was added the view out with the advent of glass. The window became part of shop front and it served the purpose of view in.

For several centuries a window was a minor entity for Illumination of domestic interiors. The door provided enough day time illumination. Domestic finer activities, such as the needle craft were conducted just inside or outside the threshold of the door. In deeper spaces, such as inner rooms, roof holes provided basic illuminance. In early public buildings, illumination was provided through smaller openings covered with parchment or alabaster. The areas of window opening though small, was distributed over a larger surface made available through increased interior heights.

Door as the only opening in the dwelling

In a tropical house admission of light is usually accompanied by heat gain, but the breeze coming through a door balances the interior environment. In tropical climates interiors tend to be darker to reduce the heat gain compared to colder climates where greater illumination is perceived as warmth. Naturally illuminated lit spaces are perceived to be healthier.

Ventilation in extreme climates such as very warm and cold, occurs through the temperature gradient between outside and inside. In hot and humid climates, the temperature gradient is not acute enough to cause natural air movement of a sufficient quantum. The need for large volume air movement is significant for moisture control in hot humid areas.

Ventilation requirements of an interior space vary depending on the number of occupants, nature of indoor cooking activities, fuels used for indoor heating and cooking, duality of distinct entry and exit points, the structure of the dwelling and scope for micro passive ventilation. To a smaller extent the ventilation needs are governed by the siting of the dwelling, such as the densely populated urban colony. Ventilation also depends on the nature of opening (cracks, crevices, holes), size of opening, number, distribution, location, orientation, and external climatic conditions (snow, rain, windy).

Micro ventilation

Cracks and gaps being unintentional are usually insufficient for heavier needs of ventilation and cooling or heating of spaces such as for toilets, kitchens, production areas and public spaces. Planned openings like windows on external face provide for such needs at the location, elevation, depth and in required quantity (such as a rate of air change -dilution, and the rate of air flow). The effectiveness of windows in achieving desired ventilation depends also on which windows are opened, how far they open, and the nature of shutter fixing.

Ventilation requirements for a dwelling are regulated by the cooking activity. In hot arid climates cooking is done outside the house, in an attached facility or semi open lean-to shades. Kitchen areas are sited in isolated spaces or corners. Cooking with a centric hearth occurred where it also contributed heat for warming. Moisture dilution is an important factor of ventilation requirements. In hot humid climates water utilities like storage and usage (bathing and washing) are placed in the Chowk like interior courtyards, outside or away from the dwelling. According to cannons of Building design, the Vastu Shastra, place of water is in the North-East side. This orientation provides for exposure to south-west face, the warmest or Sun side in the Northern hemisphere.

Punjab India -Open air – outdoor cooking minimises internal ventilation needs

Ventilation is required to dilute the odours, moisture, carbon dioxide, airborne pollutants such as dust, smoke, volatile organic compounds (VOCs), latent heat from air, objects, etc. and encourage evaporation of body moisture and thereby cause cooling.

Windows provide ventilation, more effectively in rooms with internal doors (that is a door not opening to an exterior face), and especially when the exterior face door is closed for security reasons, such as at night. Movement of air between indoor spaces, and not the outside, is called transfer-air. Transfer-air has very little role in diluting the polluted air.

Windows placed on opposite sides and on same axis are better ventilating devices. The position of window vis a vis the work plane or task is determined whether one wants a draught-breeze over the body and the task, or avoid it. The nature of shutter opening also determines the direction of the internal air movement.

Windows with shutters opening outward often obstruct the wind path, but double hung sash windows and sliding shutters which open within the frame are better as receptors. Casement window shutters with offset hinges or friction stay which create a small gap on the jamb side help in catching the breeze. Hoppers, awning and jalousie windows direct the breeze due to the angle of opening. The depth of a window and its surround also affects the nature of ventilation. Splayed sides create funnel effect to catch the breeze.

Mumbai Houses -One face for ventilation

Most building codes suggest minimum opening area (including doors, windows, etc.) @4 to 5% of the floor area. But actual ventilation requirements are higher such as during rainy days, moisture content is very high, or when during celebrations and social events lot of people gather in a room. Nominally openings (including doors) @20% of the floor area, are sufficient for the purpose of ventilation, provided some sections of the openings are located within the human height (1.75 mts). Even in unoccupied rooms some ventilation is required to remove fumes and moisture generated by materials, plants and condensation. Minimum volumetric requirements for ventilation are 23 to 25 CMt per person per hour, and 12 to 16 CMt per Kg of fuel burnt. Large sized openings create turbulent air movements, whereas cracks and crevices create a viscous or laminar flow.

Commonly ventilation is measured in terms of entire interior volume of air gets replaced per hour, it is called air changes per hour, ACH, but requirements for air for well being per person are also specified. Minimum 0.35 ACH, but the supplied air must be no less than 15 cfm/person or 7.5 l/s/person. Since 2003, the standards for ventilation have been changed on floor area basis which is from 3 CFM/100 sq. ft. or 15 l/s/100 sq. m. to the 7.5 CFM/person or 3.5 L/s/person. To find the total amount of outside air required, one needs to add 3 cfm/100 sq. ft. or 15 l/s/100 sq. m. to the 7.5 cfm/person or 3.5 l/s/person. Thus, the air change rate requirement will vary by the size of the house and the occupancy.

Ventilation is required for a fire emergency from areas like corridors, stairs, etc. Openings for ventilation are necessary for all climate conditions, but control requirements are very acute in warm and extremely cold climates, due to outward leakage of internal air.

For adequate ventilation the building must take full advantage of prevailing breezes on the site. This includes consideration of: seasonal and diurnal wind patterns, land contours and other topographical features, shape and form of the building, height of the openings, axial position of the openings, work or task plane, physical state and age of the occupants, etc. Other important conditions are position of the window, the form of the surrounds and projections and design of the window shutter.

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GLASS in ARCHITECTURE -1

Post 263 ⇒   by Gautam Shah  →

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Glass has been used in architecture in THREE major ways. It has been used as a space moulding surface material, environment controller and for the metaphysical allusions.

Central Library Seattle Washington

Architecture has always been manifestation of surfaces. The surfaces have been predominantly opaque and omnipresent. This aspect has been sought to be dissolved in many different manners. The textural character of the built mass with its varying shadows has enlivened the surface. Structures like the pyramids or the burial chambers of Newgrange were monotonous, because the texturing elements were too small for the extent of the surface. The surfaces of later structures were further surface- modulated with incised with figures, writings or colour variations of materials. Large variegation of gaps, openings and massive impositions of columns and projections further dissolved the monolithic character of the form.

Chichen Itza pyramid Mexico

The diffusion of outer skin of a building was not desirable. In Egyptian or the Indian temples it exposed the inner areas to weather. The surface conversions for texturizing must remain an overt change, and for that reason an envelope was required. The envelope in Parthenon and other buildings were exterior surface composition. The inner core, covered by the outer skin had little need for surface treatment.

Erechtheion of the Acropolis, Athens

The monolithic nature of building and its surface character began to change with additions of functional units, such as wings, blocks, towers, campaniles and ambulatory spaces. The openings were made emphatic with various architectonic elements.

St. Michael’s Church, Hildesheim Architectural elements moulding the form

Abbaye Cerisy le Foret, Normandy, France Architectural elements moulding the form

The building’s exterior surface was fairly complex arrangement of forms. The interior surfaces though remained moderately plain, devoid of any play of architectural features. Interior surfaces of the Santa Sophia, Constantinople, were masked with bends of various materials, tying up openings, columns, etc.

Santa Sophia Interior Surface Treatment > Wikipedia image by Dean Strelau

 The Glass was not yet a force as a space moulding surface material. Its size was small, life short, quality inferior and very costly. It was just an illumination element that allowed, light without rains, winds minus the cold or warmth. It replaced parchment, alabaster, etc. The walls were massive to allow large sized openings. The framing techniques with stone, wood, and lead caulking were poor.

By Romanesque period there was realization that Glass is a good controller of environment. It could simultaneously protect and illuminate the interiors. Other realization was that, glassed openings shone at night, giving a brilliant recognition to the architecture. The same glass during day time, in spite of colour staining had lusterless or dull metallic grey face.

Strasbourg Cathedral, France The glass face during day time from outside was dull metallic grey surface

The interiors of the buildings of religious order were mural painted, but for that to be seen day time illumination was required. The openings seemed narrow in proportionately heavy thickness of walls. The resolution to this was in chamfering the inner edges of sides, sills and in instances lintel heads. This method gave a ‘sense’ of a larger source of illumination. For paintings on both long walls to be visible, the openings had to be on opposite walls. The placement of openings broke the continuity of the story telling board -the murals.

St Malachys Church, Castlewellan, Chamfered edges of windows enhance the brightness

The basilica of Sant’Apollinare Nuovo in Ravenna –For wall art to be seen Windows on opposite face are necessary

Glass had its own tinge of colour which affected the colour scheme of the wall art. One way of diluting the tinge effect was to produce glass as thin as possible. This was done by blowing glass cylinders or bulbs and flattening them. This glass had imperfections that marred the visual clarity. The blown glass panes when placed in lower sections of the building distorted the scenery. Some form of occluding was required. Dwellings began to have sheer curtain masking, and in religious stained and painted glasses were used.

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