ENERGY EFFICIENT WINDOWS AND BUILDING DESIGN

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ENERGY EFFICIENT WINDOWS AND BUILDING DESIGN

• ARCHITECTS AND CONSULTANTS POINT OF VIEW.
• BY K.V.PRADEEP
• MANAGING DIRECTOR
• DVP CONSULTING PVT. LTD.
• BANGALORE,

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WHAT DO WE MEAN BY ENERGY EFFICIENCY?

• WE MEAN
• HOW EFFICIENTLY WE ARE USING ENERGY FOR VAROIUS
  SERVICES IN THE BUILDING
• IN OTHER WORDS.

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HOW MUCH LESS ENERGY THAN CONVENTIONAL METHODS WE
ARE USING TO ACHIEVE SAME OR BETTER RESULTS

• AIR CONDITIONING IS ONE OF THE MAJOR CONSUMER OF
  ENERGY IN ANY AIR CONDITIONED BUILDING

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AIR CONDITIONING LOAD INCREASES DUE TO

• SOLAR HEAT GAIN THROUGH
• WALLS
• WINDOWS
• ROOF
• ETC.

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IN A COMFORT AIR CONDITIONING APPLICATION

• SOLAR HEAT GAIN ACCOUNTS FOR AS HIGH AS 30 40
  OF THE AIR CONDITIONING LOAD
• HENCE IT IS ESSENTIAL TO REDUCE THIS HEAT GAIN TO
  REDUCE AIR CONDITIONER SIZE AND COST OF BUYING
  AND OWNING.

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EFFECTS OF SOLAR RADIATION ENTERING BUILDING

• Increased Heat and Hence stress on people
• Reduces working efficiency of people.
• Reduces Efficiency Life of machines
• Direct sunlight induces glare making visual tasks
  difficult to accomplish
• Create unsafe working conditions
• And others

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HOW DOES THIS ENTER THE BUILDING?

• SOLAR ENERGY ENTERS BUILDING BY
• CONDUCTION ( OUTER TO INNER WALL, GLASS)
• CONVECTION ( FROM INNER SURFACE TO THE
  CONDITIONED AREA)
• RADIATION ( THROUGH WINDOWS ETC.)

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THE PROBLEM IS MORE AGGRAVATED WHEN.

• Outdoor temperatures are very high
• People work in fixed postures / desks
• Ventilation is poor in the area
• Already other heat sources are in the area like
  computers etc.

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HOW TO REDUCE SOLAR GAIN?

• Solar Heat Gain can be reduced by
• Proper orientation of the building / walls /
  windows
• Control unwanted sunlight
• Choose right material for construction
• Provide Insulation for exposed Roof

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ORIENTATION

• Avoid West facing glass
• North facing glass preferred
• Prefer shading by other structures / trees etc.
• Prefer Longer south North Facing walls
  Windows

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CONTROL UNWANTED SUNLIGHT

• Retractable Sunshades
• Adjustable Louvers
• Light colored Louvers
• Projecting Roof Balcony
• Venetian Blinds
• External The best Method
• Internal
• Horizontal
• Vertical
• Special Window Glass

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Special Type of Glasses

• Reflective Glass acts as one way mirror
  reflecting incident light backwards
• Heat Absorbing Glass Heavy tinted- absorbs and
  reradiates later
• Double Glazed windows
• Neutral Tinted glass for glare reduction

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OTHER IMPORTANT POINTS

• 10 of Floor Area should be Windows for natural
  Lighting
• 5 10 floor area should be fully open able
  windows for natural ventilation.
• Forced ventilation though can not cool the area,
  can keep the area comfortable in non A/c areas.

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CASE STUDY

• SOFTWARE FACILITY GR. 3 UPPER FLOORS.
• TOTAL AREA 120,000 SFT
• EACH FLOOR 30,000 SFT
• BUILDING SHAPE 1)175 x 175 SQUARE
• 2) 300 x 100
  RECTANGULAR

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CASE STUDY

• ASSUMPTIONS
• OCCUPANCY ONE PERSON / 100 SFT
• FRESH AIR 20 CFM / PERSON
• COMPUTERS 150 W / PC
• LIGHTING 1.5 W / SFT

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CASE STUDY

• COOLING LOAD (20 GLASS AREA)
• ROOF IS INSULATED
• FOR SQUARE BLDG. - 100 TR / FLOOR
• FOR RECT. BLDG. - 98 TR / FLOOR
• COOLING LOAD (20 GLASS AREA)
• ROOF IS NOT
  INSULATED
• FOR SQUARE BLDG. - 138 TR / FLOOR
• FOR RECT. BLDG. - 136 TR / FLOOR

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CASE STUDY

• COOLING LOAD (80 GLASS AREA)
• ROOF IS INSULATED
• FOR SQUARE BLDG. - 119 TR / FLOOR
• FOR RECT. BLDG. - 114 TR / FLOOR
• COOLING LOAD (80 GLASS AREA)
• ROOF IS NOT
  INSULATED
• FOR SQUARE BLDG. - 158 TR / FLOOR
• FOR RECT. BLDG. - 152 TR / FLOOR

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CASE STUDY

• COOLING LOAD FOR THE ENTIRE RECT. BLDG. (20
  GLASS AREA)
• 356 TR
• COOLING LOAD FOR THE ENTIRE RECT. BLDG. (80
  GLASS AREA)
• 432 TR
• THEREFORE, WE REQUIRE AN ADDITIONAL 17.5
  COOLING CAPACITY IF GLASS AREA IS 80

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CASE STUDY

• RUNNING COST / YEAR
• 20GLASS AREA BLDG.
• 356TRX8HRX5DX52WX1KW/TRX RS.5X0.7
• RS. 25.9 LAKHS
• 80GLASS AREA BLDG.
• 432TRX8HRX5DX52WX1KW/TRX RS.5X0.7
• RS. 31.4 LAKHS

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CONCLUSION

• THE CASE STUDY SHOWS THAT IT IS IMPERATIVE THAT
  THE GLASS AREA BE KEPT TO A MINIMUM OR IF THIS IS
  NOT POSSIBLE DUE TO ARCHITECTURAL REASONS, TO
  SELECT A GLAZING CAPABLE OF REDUCING THE SOLAR
  HEAT GAIN.

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THANK YOU FOR YOUR TIME
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CASE STUDY

• COOLING LOAD (80 GLASS AREA)
• ROOF IS INSULATED
• FOR SQUARE BLDG. - 119 TR / FLOOR
• FOR RECT. BLDG. - 114 TR / FLOOR
• COOLING LOAD (80 GLASS AREA)
• ROOF IS
  UNINSULATED
• FOR SQUARE BLDG. - 158 TR / FLOOR
• FOR RECT. BLDG. - 152 TR / FLOOR