Strategies for Energy-Efficient Buildings for...2 Energy Performance of Buildings • Energy...
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Strategies for Energy-Efficient Buildings Dr Sameer Maithel 24 th September 2014 Jaipur
Transcript of Strategies for Energy-Efficient Buildings for...2 Energy Performance of Buildings • Energy...
Strategies for Energy-Efficient
Buildings
Dr Sameer Maithel
24th September 2014
Jaipur
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Energy Performance of Buildings
• Energy Performance Index (kWh/m2/year) is the measure
of the energy performance of buildings.
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BAU (3 shiftoffice)
BAU (2 shiftoffice)
BAU (1 shiftoffice)
Aranya Bhawan(1 shift Office)
EPI (kWh/m2/year)
* BAU data taken from Building Energy Benchmarking study undertaken by USAID ECO III Project (860 buildings)
A large scope exists for reducing energy consumption in buildings
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Parameters Influencing Energy
Performance (EPI) of a Building
Climate
Design
Building Usage User Behaviour
Controls, Operation & Maintenance
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Approach to Energy-Efficient Design
Business As Usual
Passive Measures Energy
Efficiency in Cooling & Appliances Renewable Energy
Generation
EPI
Net Energy Requirement
5 Indo-Swiss Building Energy Efficiency Project
PASSIVE MEASURES
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Building Orientation
• Orient buildings to minimize solar exposure on
wall surfaces (i.e. larger façade on North and
South direction)
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Understanding Heat Gains from
Building Envelope
• External wall – 9 inch brick (Area: 47.6 m2)
• Roof – 6 inch RCC slab (Area: 15 m2)
• Window to wall ratio: – 15% (all sides) (Area: 8.4 m2)
– Glazing type: Single clear 6mm
• No heat exchange with the ground (adiabatic)
• No internal loads
• Cooling set-point: 24oC
• Infiltration: 1 ach
Source: BEEP analysis
• Summer: Heat in-flow (May)
• Delhi (Composite Climate)
3m
5m
3.5m
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Understanding Heat Gains from
Building Envelope
Summer: Heat in-flow (May)
Delhi (Composite Climate)
Roof: 31%
Wall: 32%
Windows: 31%
Infiltration: 6%
Net heat flow per unit area
Window (8.4 m2) 43 kWh/m2
Roof (15 m2) 25 kWh/m2
Wall (47.6 m2) 8 kWh/m2
Infiltration (based on floor area 15 m2)
5 kWh/m2
Source: BEEP analysis
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Strategies for Reducing Heat Gains
from Building Envelope
Roof a) Insulation b) High reflectance c) Shading
Wall a) Insulation b) Low absorption – light colours c) Thermal mass
Windows a) Optimizing the area b) Double-glazing c) Fixed shading d) External movable
shading
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Example: Impact of Passive
Measures in a Residential Building
Passive measures for Walls & Windows
– Package of Measures –I : Use of light colors on wall (absorptivity ≤ 0.4) +
Window shades with extended overhangs + better insulation of walls +
optimised natural ventilation (~20% reduction in cooling thermal
energy)
– Package of Measures –II: Package of Measures-I+ external movable
shutters on windows (~40% reduction in cooling thermal energy)
– Package of Measures –III: Package of Measures-II with improved wall
insulation + double glazing + better building tightness (~55% reduction
in cooling thermal energy)
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Package 1
+ +
Light colors on wall
(absorptivity: 0.4)
Window shades with overhangs
with side extension
Optimized natural ventilation
200 mm AAC Blocks
(0.7 W/m2.K)
+
(~20% reduction in cooling thermal energy)
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Package 1 Measures +
Sliding shutter Hinged and top rolling
shutters
(~40% reduction in cooling thermal energy)
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+
50 mm thick XPS insulated
cavity wall 0.5 W/m2.K
Double Clear Glazing
Improved Building
Tightness
(0.3 ACH)
+
Package 2 Measures +
(~55% reduction in cooling thermal energy)
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• Raising the temperature of cooling set-point from 24 to 28 oC (~adapative comfort temperature for summer as per ASHRAE 55) can bring ~ 60% reduction in cooling thermal energy
Full Utilization of Low Energy Cooling
Techniques
• Cooling system design approach should
favour utilization of full potential of low
energy cooling techniques
– Natural ventilation
– Fans, assisted ventilation
– Evaporative cooling
• Reducing the air-conditioning energy
Refrigerant
Cooling Water
Chilled Water
Air
Evaporator
Condenser
Compressor Expansion Valve
Heat rejection temp.
CHW supply temp.
Coefficient of performance or COP
Cooling provided in kW
Energy Consumption in kW =
* Higher the COP better is the efficiency of the chiller
COP of chiller increases, if the temperature difference between “heat rejection temperature” and “chilled water supply temperature” decreases
Evaporator
Condenser
Compressor Expansion Valve
Heat rejection temp.
CHW supply temp.
• Using Water Cooled Chillers instead of air cooled (~ 2 time more efficient)
• Using HVAC design which require higher chilled water temperature e.g. chilled beams, radiant cooling, under floor air distribution system etc.
• If the building load is reduced then chilled water temperature can be raised
• Keeping the cooling tower approach temperature lower
• Duct
insulation
• Duct design
– Duct sizing
– Minimize
bends
• Air balancing
• Chilled water
pipe insulation
• Pipe design
– Pipe sizing
– Minimize bends
• Water balancing
• Right sizing of fans and pumps • All motors for fans & pumps to be Eff1 or IE2 • Installation on VFD on pumps and fans
operating at variable flow rate
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Appliances
• Select higher BEE star labeled
equipments and appliances
e.g. Transformers, Tubelights, ceiling fans,
air-conditioners, etc
Select lifts having energy-efficiency features:
a) EE features to reduce standby electricity consumption – LED/CFL for lighting, auto switch-off, avoiding dark
interiors
– High efficiency motors for ventilation, auto-switch off
b) EE features to reduce running electricity consumption – Use of VFD drives in motors
– Gearless systems
– Regenerative braking • Electricity savings of 20-30%
Common Services-Lighting
a) Design for day-lighting of corridors,
staircases, parking areas.
b) Choose energy-efficient artificial lighting
– Indoor spaces
• CFLs and T5 Tube Lights
– Outdoor spaces
• LEDs and metal halide lamps
• Optimization for height and distance
Design for energy-efficient pumping system
a) Select pump so that the head and flow parameter for the ‘Duty Point’ matches with that of the ‘Best Efficiency Point’ of the pump.
b) Design piping so as to reduce frictional losses
c) Use variable flow drives (VFDs) on pump motors.
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Solar PV technology Polycrystalline silicon
Efficiency of solar panel at standard test
conditions* (%) 13.5
Size of 1 kWp solar panel (m2) 7.4
Roof area required for 1 kWp solar panel (m2) 10
Roof area (m2) of the building 355
Available shadow-free roof area for solar (%) 60
Available shadow-free roof area for solar (m2) 213
Maximum size of photovoltaic system possible on
roof (kWp) 21
Location New Delhi Nagpur
Annual electricity generation (kWh/year) 30,904 32,232
Approach to Energy-Efficient
Design
Business As Usual
Passive Measures Energy
Efficiency in Cooling & Appliances Renewable Energy
Generation
EPI
Net Energy Requirement
37 Indo-Swiss Building Energy Efficiency Project
Thank you!
www.beepindia.org
