Managing energy by design with low energy comfort systems

by Punit H Desai, Green Initiatives, Infosys Ltd

Energy consumption distribution

Air conditioning40%

Lighting / Raw power15%

UPS/Computing40%

Misc.(5%)

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Managing energy with low energy comfort systems

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Managing HVAC energy

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Reduce Air-conditioning load by design

Goal : Limit external heat gain to less than 1 watt/sqft & 1 TR should cool min 550 sqft

Building shape and orientation, Roof Insulation (Over deck roof insulation) Reflective roofs Wall Insulation - Double brick wall construction with insulation and air cavity Window wall ratio Heat avoiding Glazing (Double glazed windows with argon filling) Efficient lighting and computing devices

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Do efficient design and select efficient technologies

Goal : HVAC system ikw/tr < 0.6 for plant room

Innovative cooling technologies – Radiant cooling Radiant cooling separates out latent and sensible loads Uses 16 deg C chilled water for sensible cooling Takes benefit of lower ambient humidity whenever avaialble

Low pressure drop design for piping and equipments Low pressure drop design for AHUs and ducting Automation for smart operation High efficiency chillers, pumps and cooling towers

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Building Orientation – Minimum surface area and windows on E & W

West East

North

South

Building envelope

• Efficient walls: Insulation for the walls minimizes heat gains into the building through walls. The exterior walls are cavity brick walls with insulation that let in only 1/5th of the heat into the building compared to a conventional 9” brick wall.

Heat transfer co-efficient:

U – 0.4 btu/hr ft2 F ( Insulation – XPS – R5 with 25mm), Total R-14

Double brick cavity wall with insulation and air gap

100mm

200

50

75

Interior Exterior

Building envelope

• Efficient roof: Insulation for the roof minimizes heat gains into the building through the roof. The roof for Mysore SDB-5 are insulated over deck and let in only 1/8th of the heat into the building compared to a conventional RCC roof.

Heat transfer co-efficient:

U – 0.35 ( Insulation – XPS – 75 mm, no air gap), Total R-16

Insulation above the RCC layer and sloping

Building Envelope: High Performance glazing

35 0C24 0C

900 W

540 W360 W

55 W

35 0C

24 0C

900 W

90 W

810 W

12 W

Single glass Spectrally selective double wall glass with Argon filling

Single Glass

U = 5

Double pane glass with argon filling

U = 1.2 , SHGC =0.2

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Window wall ratio, differs on all sides

Double brick wall with insulation

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Radiant cooling technology – chilled water @ 16 deg C embedded in slab

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Managing Lighting energy

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Strategy 1 : Maximize day lighting, use as much natural light as possible

Goal : 90% of the area should be day lit

Limit floor depth to allow maximum day light coverage (20 m) Split the window into view pane and day light pane Use suitable glass for view pane and day light pane (Daylight to have high VLT) Use internal light shelves for effective day light penetration Use shading to cut glare

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Day light pane

View pane

External shading

Smart glazing

Internal Light shelf

Building envelope

• Building simulation used to design the shading devices• Minimize heat gain• Minimize glare from sunlight• Maximize daylight in the spaces

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Strategy 2 :Design efficient system

Goal : Total connected lighting load should be less than 0.5 watt/sqft

Use lighting simulation programs to optimize lighting fixtures (gives 30% reduction) Use high efficiency lights and fixtures (T5) Use LED in common areas, stair case, rest rooms Use occupancy sensors in meeting rooms, conf rooms, rest room

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Managing Computing energy and plug loads

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Managing IT and plug loads

Reduced number of plugs per workstation Segregated UPS plug points from raw power plug points Energy efficient IT procurement Selection of high efficiency and modular UPS (greater than 94% efficiency) Developed software to switch off computers automatically based on employee

prescribed time (Terminator application) Employee awareness programs

Managing energy by operations

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Benefit to Infosys

In 2007-08

• Average for software buildings (incl. lights, AC, computers, etc.)

Building energy: 200-240 kWh/sqm per year

• Average for software buildings across campuses

Lighting design: 1.2-1.4 W/sqft

• Average installed cooling capacity across campuses

AC design: 300-350 sqft per TR

• Total electrical load for software buildings including chiller plant

Electrical design: 6.5 W/sqft

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In 2011-12

• Average for software buildings (incl. lights, AC, computers, etc.)

Building energy: 90 kWh/sqm per year

• Average for software buildings across campuses

Lighting design: 0.5 W/sqft

• Average installed cooling capacity across campuses

AC design: 550-650 sqft per TR

• Total electrical load for software buildings including chiller plant

Electrical design: 3.5 W/sqft

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~55% lower

~60% lower

~36% lower

~46% lower

Thank you

• www.infosys.com

• The contents of this document are proprietary and confidential to Infosys Limited andmay not be disclosed in whole or in part at any time, to any third party without the priorwritten consent of Infosys Limited.

• © 2011 Infosys Limited. All rights reserved. Copyright in the whole and any part of thisdocument belongs to Infosys Limited. This work may not be used, sold, transferred,adapted, abridged, copied or reproduced in whole or in part, in any manner or form, or inany media, without the prior written consent of Infosys Limited.

Punit H. DesaiSenior Manager – Green InitiativesPunit_desai@infosys.com+91 7829918740