lecture-4_energy efficiency in buildings

7/25/2019 Lecture-4_Energy Efficiency in Buildings

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2Energy Use in Buildings

How to use Energy Efficiently?

Daylighting and Solar Techniques

AR L2418 DESIGN OF GREEN BUILDINGS

A lecture by Ar. Sachin Harry

5Cooling Techniques

1What is ‘Energy’ & ‘Efficiency’?

INTRODUCTIONINTRODUCTION

•• What is Energy?What is Energy?

• Energy is the ability to do work.

• Energy can neither be created nor be

destroyed but can be transformed from oneform to another.

• Energy sources are –

– Renewable and Non-Renewable

– Non-Renewable sources cause pollution



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INTRODUCTIONINTRODUCTION

•• What is Efficiency?What is Efficiency?• CAMBRIDGE Advanced Learners’ Dictionary states –

• when someone or something uses time and

energy well, without wasting any.

• SPECIALIZED the difference between the amountof energy that is put into a machine in the

form of fuel, effort, etc. and the amount that

comes out of it in the form of movement.

ENERGY USE IN BUILDINGSENERGY USE IN BUILDINGS

• An estimated two-thirds of the commercial and

high-rise residential structures that will be

standing in India in 2030 have yet to be built*.

• Buildings already consume 30% of India’s energy.

• That puts India at a critical juncture as it seeks

new ways to power its growing economy, and

resolve its existing, chronic energy shortages.



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• The Indian government is looking for answers

everywhere, planning hundreds of new coal-fired

power plants, nuclear power plants*, hydroelectric

dams, and expanding solar power^ and other

renewable energy sources~.

• But the cheapest, cleanest, and fastest way for India tobring power to people who need it is energy efficiencyenergy efficiency.

• According to McKinsey & Company, India can save $42

billion every year just by reducing energy waste in

buildings.


40%

30%

30%

Distribution of Energy Use in Buildings

Electric Lighting Heating and Cooling Other



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HOW TO USE ENERGY EFFICIENTLY?HOW TO USE ENERGY EFFICIENTLY?

•• Energy efficiencyEnergy efficiency is “using less energy to

provide the same service”.

• Major use of energy in buildings are through

Lighting, Heating and Cooling.• Therefore, in order to use energy efficiently it

is important to design the building climate

responsive and also incorporate new as well

as time-tested solar techniques.



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• Some passive design strategies has to be adopted to

optimise building design that controls heat gain and

allows maximum natural light –

– Optimum orientation;

– Internal space arrangement (thermal buffer zone);

– Allocation of building openings (least insolation*);

– Sizing of openings (limitation of window-wall-ratio and

skylight-roof-ratio);

– Appropriate shading design (facade shading and

fenestration shading); and

– Adequate daylighting.

* Insolation= Incident Solar Radiation

• Energy Efficiency in buildings –

– Daylighting

– Solar techniques

• Active Solar

• Passive Solar

– Cooling Techniques

• Active Cooling

• Passive Cooling




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DAYLIGHTINGDAYLIGHTINGThe daylighted area is the daylight

illuminated floor area under horizontal

fenestration (skylight) or adjacent to

vertical fenestration (window).

BASIC DAYLIGHTING STRATEGIESBASIC DAYLIGHTING STRATEGIES

1. Orientation

– For daylighting,

• when winter heat

is desirable, use

south-facing

glazing.

• when winter heat

not desirable, usenorth-facing

glazing.

• without summer

overheating or

severe glare,

avoid east and

west glazing.



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CLERESTORY

2. Lighting through the roof – Except for the use of light wells, only one storey or the top floor of multi-

storey buildings can use overhead openings.

– Advantages

• Uniform illumination over very large interior areas, while windows it ’s 15 ft. limit.

• Horizontal openings receive more light than vertical openings.

– Disadvantages• It can trap heat in summers.

• Shading horizontal openings is more difficult than vertical openings.

BASIC DAYLIGHTING STRATEGIESBASIC DAYLIGHTING STRATEGIES2. Lighting through the roof

– Therefore, it’s more appropriate to use vertical

openings on the roof in the form of clerestory

windows, monitors, or saw tooth arrangements.



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3. Form

– The form of the

building not only

determines the mix of

vertical and horizontal

openings that is

possible, but also how

much of the floor areawill have access to

daylighting.


BASIC DAYLIGHTING STRATEGIESBASIC DAYLIGHTING STRATEGIES4. Space Planning

– Open space planning is

very advantageous for

bringing light to the

interior.

– Glass partitions can furnish

acoustical privacy without

blocking the light.

– When visual privacy is also

needed, venetian blinds or

translucent materials could

be used.

– Alternatively, the

partitions can have glass

above eye level only.



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5. Colour

– Light coloured facades

are important not only

to reduce heat gain but

also to increase the

availability of daylight.

– Light coloured interiors

will not only reflectlight farther into the

building, but also

diffuse it to reduce

dark shadows, glare,

and excessive

brightness ratios.


6. View and Daylighting

– Use separate openings for view and daylighting.

– Use high windows, clerestories, or skylights for excellent

daylighting, and use low windows at eye level for view.

– High glazing should be clear or spectrally selective to maximise

daylight.

– The view glazing can be tinted or reflective to control heat gain.



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BASIC WINDOW STRATEGIESBASIC WINDOW STRATEGIES

• Guidelines –

– Windows should be high on the wall, widely

distributed, and of optimum area.

– If possible, place windows on more than one wall.

– Place windows adjacent to interior walls.

– Splay walls to reduce the contrast between windows

and walls.

– Filter daylight by using trees or by trellises* and

screens.

– Shade windows from excess sunlight in summer.

– Use movable shades.* a light frame made of bars of wood or metal crossed over each other, fixed to a wall for plants to grow up.



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SOLAR TECHNIQUESSOLAR TECHNIQUES

• Active Solar Techniques include –

– Solar electricity,

– Solar water heating

• Passive Solar techniques include –

– Direct gain (Greenhouse),

– Indirect gain (Trombe Wall), and

– Combination of the both (Sunspace, Conservatory)

PASSIVE SOLAR TECHNIQUESPASSIVE SOLAR TECHNIQUES

Greenhouse effect in buildings



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Trombe Wall


Sunspace



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Conservatory


Conservatory



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Conservatory


Conservatory



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COOLING TECHNIQUESCOOLING TECHNIQUES• Passive Cooling techniques include –

– Cooling with ventilation

• Hot & Dry Climate (Wind scoops, Wind towers, “Mashrabiya”, Small and

Deep courtyards, high mass walls, etc.)

COOLING TECHNIQUESCOOLING TECHNIQUES• Passive Cooling techniques include –






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COOLING TECHNIQUESCOOLING TECHNIQUES

• Passive Cooling techniques include –




• Warm & Humid Climate (Large windows, Large overhangs, High ceilings,

Low mass walls, Large and shallow courtyards, Deep verandahs, etc.)










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– Radiant Cooling (Roof Insulation – Direct & Indirect)











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– Evaporative Cooling• Direct (Desert coolers)

• Indirect (Roof ponds)








– Radiant Cooling (Roof Insulation – Direct & Indirect) – Evaporative Cooling

• Direct (Desert coolers)


Evaporative coolers

(swamp coolers)

Indirect Evaporative Cooling(Roof Pond)

Wind Tower



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– Stack Effect (Solar Chimney)














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– Earth Cooling (Earth sheltering, Earth Tunnels)















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– Dehumidification with a ‘Desiccant’ (Drying agent like silica gel, natural

zeolite, calcium chloride, etc.)

THOUGHT FOR THE DAYTHOUGHT FOR THE DAY

BE GENEROUS AND SHAREBE GENEROUS AND SHARE

YOUR FOOD WITH THE POOR.YOUR FOOD WITH THE POOR.

YOU WILL BE BLESSED FOR ITYOU WILL BE BLESSED FOR IT..

-- PROVERBS 22:9, THE HOLY BIBLEPROVERBS 22:9, THE HOLY BIBLE



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Go Green…

Save our planet

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