General design principles
3.4 Day lighting
3.4.3 Shading Devices
3.4.3.3 Solar control glazing
Solar control glazing are very effective against heat flow across the window but can reduce the transmission of light inside. The choice of glazing affects the daylight, solar heat gain, and heat loss through a window. These are measured by visible transmittance, the total solar transmittance and the U value. The following are the different glazing types
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· Single glazing gives the best daylight. It offers little resistance to the passage of heat. The small amount of insulation that single glazing does provide is actually due to thin films of still air that exist next to the glass.
· Double‐glazing offers much better insulation. It comprises two panes of glass with a sealed space between. The space is filled with air or an inert gas with better insulating properties than glass. It gives about 20% less daylight than single glazing.
· In low‐E (low –emissivity) double glazing, the reduction in the daylighting factor is by another 10% with respect to double glazing.
· Tinted double‐glazing has low visibility, thus cutting out daylight. Typically, more than 2sq.mt of tinted glazing will be required to admit as much daylight as 1sq.mt of clear glass.
Design considerations for daylighting as per various climates (Hot & Dry Climate)
Orientation
Orient the buildings with the long axes in the east‐west direction so that the longest walls face north and south and only the short walls face east and west.
Key factors
· Adequate shadings on the south side to cut‐off direct solar radiation during the summer months.
· Airflow need not be encouraged through large windows, as the daytime air is hot.
· Avoid externally reflected light from the ground and other external surfaces, unless great care is taken to avoid glare.
Recommended design variables/strategies
· Smaller openings that are efficiently shaded.
· Buildings with compact internal planning as courtyard type, with dense groping so that the east and west walls are mutually shaded.
· High level windows which would admit reflected light to the ceiling
· Vertical strip windows at the corner of the room to avoid excessive brightness and provide a light wash on the walls.
L I T E R A T U R E
S T U D Y 4. BUILDING
MATERIALS
For years the building industry had been dependent on a seemingly endless supply of high quality materials, supplies and energy resources. These become more significant when buildings are a global scale consume about 40% of the raw stone, gravel
and sang, 25% of wood, 40% of energy and 16% of water each year.A building industry that depends on diminishing resources will ultimately become more costly as the resources will continue to be depleted, and would thus pose a negative impact.
The underlying principle assumes that allstages in the life of a material– right from the raw material, extraction, manufacture and transportation to the installation,
operation, maintenance, and the recycling and waste managementcause some degree of environmental impact which needs to be evaluated. The need for this analysis is justified when considering the present state of the environment, and hence would provide a sustainable format for the evaluation of efficiency of building material.
Sustainable materials have five major benefits
1. They have a similar or lower price compared to traditional materials.
2. They do not exhaust the existing supplies of finite materials 3. They save energy and reduce harmful emissions
4. As they are encouraged by the building control, planning permissions are more likely to be received.
5. Since they are less harmful to occupants, they make healthier buildings.
Building materials are mostly made from naturally available materials like clay, stone, sand or biomass. Proper selection of building materials would help to conserve these natural resources.
A material that is suitable for one place may not be suitable elsewhere. We also need to understand that the building styles and design are heavily influenced by prevailing fashions, especially the fashions in the developed world. This was one of the reasons why many modern construction materials could ease out more durable, climate responsive traditional building materials in the developing world. The points to be noted for material and product selection are:
“The use of sustainably managed materials is an environmental responsibility in contributing towards a sustainable habitat.”
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ü Usenaturally available materials, especiallyorganic renewable materialslike
timber, trees, straw, grass, bamboo etc. Even non‐renewable inorganic materials like stone and clay are useful, since they can be reused or recycled.
ü Use certified timber. Check the reliability of the certificates, as forgery is possible.
ü Do not use sand quarried from coral reefs.
ü Check origin of soil for land filling.
ü Check whether quarry sites are rehabilitated.
ü Use materials with low‐embodied energy content for all structural work in fill systems.
ü Uselocally available materialsand technologies, employing local work force.
ü Use materials amenable for reuse and recycling. Pure material like bricks, wood, concrete, stone, metal sheets are most suitable for this purpose. Composite materials like prefabricated solid foam‐metal or foam‐plaster elements are difficult to separate and to recycle.
ü Use industrial waste‐basedbricks / blocks for non‐structural or infill wall system.
ü Reuse/ recycle construction debris.
ü Minimize use of wood for interior worksand use any of the following in place of wood.
ü Composite wood products such as hardboards, block boards, lumber‐
core plywood, veneered panels, particle boards, medium/ low‐density fibreboards made from recycled wood scrap from sawmill dusts or furniture industry and bonded with glue or resin under heat and pressure.
ü Materials/ products made from rapidly renewable small‐diameter trees and fast‐growing low‐utilized species harvested within a ten‐year cycle or shorter, such as bamboo, rubber, eucrasia, eucalyptus, poplar, jute/cotton stalks, etc. The products include engineered products, bamboo ply boards, rubber, jute stalk boards, etc.
ü Products made from wastes. These could be wood waste, agricultural wastes, and natural fibres, such as sisal, coir, and glass fibre in inorganic
combination with gypsum, cement, and other binders, such as fibrous gypsum plaster boards, etc.
ü Salvaged timber and reused wood products such as antique furniture.
ü Use water‐based acrylics for paints.
ü Use acrylics, silicones, and siliconized acrylic sealants for interior use.
ü Use adhesives with no/ low Volatile Organic Compound (VOC) emissions for indoor use. It could be acrylics or phenolic resins such as phenol formaldehydes.
ü Use water‐based urethane finishes on wooden floors.
ü Use particleboard made with phenol‐formaldehyde resin rather than urea formaldehyde, to control indoor VOC emissions.
ü Avoid the use of products using asbestos and CFC.
ü Minimize the use of metallic surfaces and metallic pipes, fitting, and fixtures.
ü Use products and materials with reduced packaging and/ or encourage manufacturers to reuse or recycle their original packaging materials.
ü Wherever possible,use permeable wall structures made of palm leaves, reed, grass or bamboo to promote aeration and low heat storage.
L I T E R A T U R E
S T U D Y 5. BUILDING
TECHNOLOGIES
Indian architecture has been the most enduring evidence to technological achievement when seen in the frame of culture, civilization, and range of variations in the Indian climatic conditions. The building technologies have been developed in the chronological course of time. In a streamlined manner, these technologies speak the language of the built form developed against the harshness of the prevailing
climate. The most prominent traditional building techniques in ancient India incorporated the use of stone, timber and soil.
The following are the general building technologies implemented for a residential high‐rise construction
High‐ rise construction (residential)
Roofing/flooring systems Zipbloc system, prestressed slab, hollow floor slabs, precast waffle/cored units, precast in situ thin ribbed slabs, precast waffle slabs
Walling systems Burnt brick masonry: Fly ash/sand lime/Fal‐ G, reinforced grouted brick masonry, interlocking bricks, reinforced hollow bricks with framed RCC construction, precast stone blocks.
Precast concrete blocks: Hollow/fly ash based aerated or cellular, composite ferro‐cement walling, interlocking concrete blocks, curtain walls,
structural glazing systems.
Doors / windows Precast RCC doors and windows, PVC doors/
windows shutters, partitions, energy‐efficient windows, fiberglass reinforced plastic doors, resin bonded sawdust door panels, natural fiber
reinforced polymer doors/windows. MDF particle board doors/windows. Gypsum based ceiling tiles, doors/windows, partitions, demountable systems with various types of recycled wooden boards.
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