Sanyogita Manu and Satish KumarInternational Resources Group
New Delhi, India
Presented By
Aalok DeshmukhInternational Resources Group
BauSIM 2010, Vienna, Austria, 22-24 September 2010
Architectural Design Optimization for Energy efficiency using Mixed-mode system:
Tracing the Challenges and Opportunities in a Warm-humid Climatic Context
Presentation Outline
Context
Challenges and barriers Climate
Stakeholders
Simulation
Thermal Comfort
Conclusion
Acknowledgement
References
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Context
3 BauSIM 2010, Third German-Austrian IBPSA Conference, Vienna, Austria, 22-24 September 2010
USAID ECO-III Project – Establishment of Regional Energy Efficiency Centres (REECs) in India
REEC KolkataHome Appliances
West Bengal Renewable Energy Development Agency
REEC NagpurSmall and Medium
EnterprisesSEE-Tech Solutions Pvt. Ltd.
REEC AhmedabadBuildings
CEPT University
Enhance energy efficiency awareness and education among energy end-users Facilitate showcasing and demonstration of energy efficient products for public at large Promote development (incubation) of energy efficient technologies Encourage research and interdisciplinary collaboration on energy efficiency Catalyze the development and growth of energy efficiency market and business in the
country
Context
Energy Conservation Building Code (ECBC)
Covers new buildings and ensures minimum energy performance requirements
Launched by Govt. of India on 27th May, 2007
Building components included
Building Envelope (Walls, Roofs, Windows)
Lighting (Indoor and Outdoor)
Heating Ventilation and Air Conditioning (HVAC) System
Solar Water Heating and Pumping
Electrical Systems (Power Factor, Transformers)
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Context
Initial Design Proposal:
Reduce solar heat gain by incorporating different external shading devices - a combination of horizontal and vertical shading devices on south and south-west facades and vertical shading devices on north and east
Hollow brick wall with insulation to reduce conductive heat gain from outside
High performance glazing to mitigate solar radiation
Multiple numbers of small openings with deep overhangs on south facade and relatively larger openings on the north
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Context
6 BauSIM 2010, Third German-Austrian IBPSA Conference, Vienna, Austria, 22-24 September 2010
Building description:
Total built-up area: 250m2, distributed over three floors Ground floor: Demonstration
First floor: Training & offices
Second floor: Rest rooms & terrace
Overall WWR: 20%
Challenges and Barriers
CLIMATE: Warm and humid
High temperature Mean monthly: 19-30°C
Maximum > 40°C
Low diurnal range
High humidity Annual average RH: 78%
Moisture ingress, mould growth
Low wind 3-7m/s for 10 months
50% of the blowing wind is Calm
High solar radiation Annual Global average: 4100Wh/m2
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Challenges and Barriers
STAKEHOLDERS: Client, Architect and Product manufacturers
Public undertaking Absence of clarity in the program
Notions of ‘Green’ building limited to a building with no air conditioning
Restricted possibility of experimentation with construction techniques and materials beyond the given set of specifications
Current specifications are outdated
Limited budget leads to cutting down on the short-term expenditure
Interaction between stakeholders
Unavailability of appropriate Technological solutions to assist path-breaking designs in energy efficiency
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Challenges and Barriers
SIMULATION-based Analysis
Simulation inputs: Schedules for occupancy, activity, systems
Modeling of mixed-mode system: temperature bands for natural ventilation
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Simulation
Energy Performance
Energy Conservation Building Code –Envelope measures
‘Zoned’ Mixed-mode design (different spaces, same time)
Thermal Comfort
‘Change-over’ Mixed-mode design (same spaces, different times)
PMV – Modified (Adaptive thermal comfort)
10 BauSIM 2010, Third German-Austrian IBPSA Conference, Vienna, Austria, 22-24 September 2010
Optimizing
Building
Envelop
Reducing
Internal Loads
Wall optimization
Insulation
Cavity
Window optimization
Improved glazing: reflective and low-
emissivity coatings
Improved frame
Reducing Lighting Power
Density (LPD)
Reducing Equipment Power
Density (EPD)
Daylight sensors
Natural Ventilation
Daylighting
Passive
strategies
ENERGY CONSERVATION MEASURESENERGY CONSERVATION STRATEGIES
ECBC Compliant
Design
COMPARATIVE
ANALYSIS: Stage 2
Improved
Design (with
ECMs)
COMPARATIVE
ANALYSIS: Stage 1
Active strategies
Typical Building Proposed
Design
Proposed Design
Efficient Packaged AC
Solar Absorption Cooling
Dehumidifiers
Process followed for ECBC compliance, showing various ECMs
Challenges and Barriers
THERMAL COMFORT
Mixed-mode
Natural ventilation
Increased air speed
11 BauSIM 2010, Third German-Austrian IBPSA Conference, Vienna, Austria, 22-24 September 2010
RUN DESCRIPTION HVAC NAT-VENT MIXED-MODE
1 Cooling setpoint 24 °C On On On
2 Cooling setpoint 26 °C On Off Off
3 Without Ceiling fans Off On Off
4 With Ceiling fans Off On Off
Challenges and Barriers
THERMAL COMFORT
PMV Mean Air temperature
Mean Radiant temperature
Relative humidity
Air speed
Clothing
Activity level
Studies have shown PMV model to predict thermal sensations warmer than occupants actually feel in naturally ventilated spaces
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Challenges and Barriers
THERMAL COMFORT
13 BauSIM 2010, Third German-Austrian IBPSA Conference, Vienna, Austria, 22-24 September 2010
Mathematical
model of PMV
Adaptive mechanisms
Thermal Comfort
Psychological adaptation: An occupant’s past thermalexperiences have an impact on his EXPECTATIONS ofcomfort
Behavioral Adaptation: People change/slow down theirMETABOLIC RATE (activity) when they feel warm Fanger &Toftum
Challenges and Barriers
MODIFIED PMV
Spreadsheet for calculating hourly PMV (based on ASHRAE Thermal Comfort algorithms)
Calculation inputs: Mean air temperature (Simulation hourly results)
Mean radiant temperature (Simulation hourly results)
Relative humidity (Simulation hourly results)
Metabolic rate: 60 W/m2 (light office work)
Clo value: 0.75 (winters), 0.5 (summers)
Calculated PMV → Modified PMV To account for slowing down of metabolic rate: metabolic rate reduced by 6.7%
(based on Fanger & Toftum PMV extension model)
Resultant PMV adjusted using expectancy factor ‘e’ of 0.7
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PPD decreases from 50 to 35% for Modified PMV
Decrease in PPD is more significant when air movement is increased using ceiling fans – PPD calculated using Modified PMV presents a more realistic prediction of thermal comfort in naturally ventilated spaces (with ceiling fans assisting air movement)
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31%
22% 28%
37%
0
10
20
30
40
50
60
70
1 2 3 4
Annual Average Area-weighted PPD
Calculated Modified
PPD increases from Run 1 to Run 2 in conditioned zones due to increase in cooling setpointPPD Increases (to double) from Run 1 to Run 2 in non-conditioned zones due to unavailability of Nat Vent in Run 2 – Nat Vent is an important strategy in non-conditioned zonesPPD decreases (to about half) from Run 3 to Run 4 due to increase in air
speed in Run 4 (ceiling fans)
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0
10
20
30
40
50
60
70
80
90
1 2 3 4
Annual area-weighted 'Modified' PPD
Building Conditioned area Non-conditioned area
Run 1 (Mixed-mode AC) and Run 4 (Nat Vent + Ceilings fans) coincide, except for peak summer months – Air-conditioning can be avoided during the rest of the year through passive measures
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0
10
20
30
40
50
60
70
80
90
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Monthly Area-weighted average 'Modified' PPD
1
2
3
4
Conclusion
Integrated Design Process assumes greater importance in a multi-stakeholder participation scenario
Change of role: Technical assistance → Facilitation
Keep all stakeholders in the loop
Vary the extent of engagement at each stage
Need for a Thermal Comfort Model for India - Warm-humid climate
Significance of Ceiling Fans in Warm-humid climate towards improving thermal comfort
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Acknowledgement
United States Agency for International Development (USAID)
Bureau of Energy Efficiency, Ministry of Power, Government of India
West Bengal Renewable Energy Development Agency (WBREDA), Department of Power and NES, Government of West Bengal
P. C. Thomas and Justin Wong, Team Catalyst
Prakalpa Architects, Kolkata
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References
Brager, G. S., de Dear, R. J. 1998. Thermal adaptation in the built environment: a literature review, Energy and Buildings, Vol. 27, pp. 83-96
(BIS) Bureau of Indian Standards. 2005. National Building Code of India, Second Revision 2005, New Delhi, India
EnergyPlus. 2009. EnergyPlus Engineering Reference, U. S. Department of Energy
Fanger, P. O., Toftum, J. 2002. Extension of the PMV model to non-air-conditioned buildings in warm climates, Energy and Buildings, Vol. 34, pp. 533-536
Fountain, M., Brager, G., de Dear, R. 1996. Expectations of indoor climate control, Energy and Buildings, Vol. 24, pp. 179-182
Nicol, J. F., Humphreys, M. A. 2002. Adaptive thermal comfort and sustainable thermal standards for buildings, Energy and Buildings, Vol. 34, pp. 563-572
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Thank you
Contact:
USAID ECO-III Project, New Delhi, India
www.eco3.org