These slides use concepts from my (Jeff Funk) course entitled analyzing hi-tech opportunities to look at how improvements are occurring in zero energy buildings. Improvements in the energy efficiency of appliances, in aerogels for insulation, in solar cells for electricity generation, and in passive solar design are helping us reduce energy usage. The goal is zero energy usage of external electricity and fossil fuels.

1. Zero Energy Buildings:
Building a Sustainable Future
Chen Jia, Shubham Duttagupta, Martin Heinrich, Ankit Khanna,
Yeo Boon Khee
MT 5009 Analyzing Hi-Technology Opportunities
Class project

2. The definition of a Zero Energy Building
2010 US end-use emissions
 Def: ZEBs generate equal or
from fossil fuel combustion
more energy than they
consume annually
Emission in Tg (CO2 eq. )
 ZEB is a 3 fold concept:
 Local use of green energy
sources (our focus: BIPV)
 Energy efficiency: passive
design and efficient
technologies
 Optimal grid connections
Adapted from: U.S. Greenhouse Gas Inventory Report (US Environmental Protection Agency), 2012

3. A qualitative look at ZEB costs
ZEB’s advantage over the lifecycle
Regular buildings
ZEBs High construction cost offset
Future ZEBs by low operating costs
Construction cost ZEBs higher than
Cumulative costs
conventional buildings
Conventional
Lowering initial and operating
cost by improvements in ZEB
technologies
Years
(Cumulative cost = construction cost + operation costs)

4. ZEBs are energy efficient
Technologies and design to reduce energy usage
 Reduction of energy demand is
central to the ZEB concept
 Energy efficiency is attained
through:
 High efficiency HVAC
 Energy-efficient artificial
lighting
BCA Academy building, Singapore  Passive solar design
 Maximizing day lighting

5. Photovoltaics: Technology and
Integration

6. World cumulative PV installation
Rapid growth in PV market, average annual growth rate of 40%
Sources: International Energy Agency (IEA) 2008

7. Grid parity in Singapore
a scenario under the assumption of net metering
0.40
+5%/a
0.35
Electricity costs/prices in [S$/kWh]
PV cost
0.30
0.25 0%/a
Utility price -7%/a
0.20
0.15 -13%/a
0.10
0.05
0.00
2011 2012 2013 2014 2015 2016 2017 2018 2019 2020
Calendar year
Source: Luther et. al., ICMAT, 2011

8. Market shares of PV technologies
Other
100%
a-Si ClS
80%
CdTe
Ribbon c-Si
60%  Currently, silicon
Multi c-Si dominates the PV
market
40%
 Thin film materials
(CIS, CdTe, etc.)
20% growing slowly
Mono c-Si
0%
Source: S. Glunz, Fraunhofer ISE; Data Photon Magazine 2011

9. PV Technologies
Thin film
Dye-Sensitized
Organic
Best efficient in lab using different technology
Source:Multi-Junction Solar Cells, ICMAT Yamaguchi 2011

10. Building Integrated Photovoltaics (BIPV)
Concept, key aspects
 PV materials replace
conventional building
materials
 Integration
 Addition to existing
building (e.g. roof-top PV
installation)
 Replacing building
envelopes (e.g. PV façade
or window)
 Aesthetically pleasing
 Connecting to utility/grid

11. BIPV installation
Split by application (worldwide estimation)
roofing
facades
transparent windows
Source: Lux research, BIPV, 2010

12. Vertical scaling for ZEBs
Façade and window integration becomes more prominent
 Modern ZEBs need to be several
stories high
 This would improve natural
ventilation and allow more
daylight
 Trade-off: roof PV no longer
sufficient for energy demand
 Façade and window integration
become more prominent
An artistic impression of the
Pearl River Tower in China

13. Learning curve of BIPV
Experience for 20 years
Drivers:
 Decrease in BIPV cost driven by reduced PV cost and increased efficiency
 Special BIPV feed-in-tariffs
 Architects and BIPV R&D Source: International Energy Agency, PV report, 2004
Source: K.Sopian et al , ISESCO Science and Technology Vision - Volume 1, 2005

14. The need for grid connected ZEBs
PV electricity output varies with time
Daytime surplus energy
can be fed back to the grid
Grid connections
are necessary
Daily electricity supply (PV) and demand, averaged over one year
Source: Data from the BCA academy building, Singapore’s first ZEB

15. Energy efficient technologies for
buildings

16. Energy consumption in Singapore
By end-use
Commercial sector Residential sector
Others Air-
Office Air- Washing 8%
Equipment & conditioner
conditioning 6%
Others Kitchen 30%
52%
25% Appliance
6%
Video
Trans- Equipment
portation 10%
Fans
7%
4%
Water
VentilationLighting Heater Lighting Refrigerator
4% 12% 9% 10% 17%
Major usage:
1. Air conditioning/ Refrigerator
2. Lighting
Source: Office Building Energy Saving Potential in Singapore, Cui Qi, 2006; E2 Singapore, NEA, 2010

17. Air-conditioning /Refrigerator
Working principle
Compressor Condenser
1. Compressor: Gas compression
and heating
2. Condenser: Condensation of hot
outside gas to liquid
inside 3. Valve: sudden expansion of
liquid => partly evaporation and
cooling
4. Evaporator: Full evaporation of
mist and cooling
Evaporator Valve

18. Possible improvements for AC
Identified, selected technologies for AC with high potential
Air conditioning
Source: Energy Savings Potential and R&D Opportunities for Commercial Building HVAC
Systems, U.S. Department of Energy 2011

19. Improvements for air-conditioning
Example: Liquid desiccant
 Singapore: Over cooling and
reheating air to reduce humidity
 Solution: Liquid desiccant (like
silica gel, but liquid)
 Liquid desiccant: High affinity for
water, attracts moisture in
conditioner
 Regenerator heats liquid
desiccant to release moisture
Source: Energy Savings Potential and R&D Opportunities for Commercial Building HVAC
Systems, U.S. Department of Energy 2011

20. Outlook AC efficiency
AC efficiency (Energy Efficiency Ratio, EER) projection
Average efficiency of all AC unit for sale
MEPS: minimum energy efficiency requirements, target set by Chinese
government
Source: Energy efficiency of air conditioners in developing countries …, OECD/IEA, 2007

21. Energy efficient lighting outlook
Current and projected advances in lighting (section 8 by Prof. Funk)
projection
LED
CFL
Light bulb
In summary:
• Recent advances in CFLs Energy consumption of lighting will
• Future advances in LEDs projected become less
Source: Solid State Lighting, U.S. Department of Energy (2010)

22. Passive design

23. Thermal insulation
Reducing overall HVAC usage
 Insulation prevents heat
transmission, therefore
overall HVAC usage
 Past 20 years: only
incremental improvements
in insulating material
 Recently, aerogels explored
as new insulating
Insulation prevents heat transmission into technology
building (summer) and from buildings (winter)  Aerogels consist of network
of bubbles, with very thin
cell walls

24. Aerogels cost and performance
Commercially available building insulation materials
Insulating Material Thermal conductance Cost per ft3 (US$)
[W/m²·K]
Polystrene Foam 0.20 8.04
Rock Wool 0.36 1.64
Fiber Glass 0.32 1.63
Cellulose 0.29 1.81
Pure Silica Aerogel 0.05 2500
Clay Polymer Aerogel (Aeroclay) 0.05 8
 Aerogels commercially available and used mainly in clothing and for
scientific applications (because of higher costs)
 New startup Aeroclay (2010) is commercializing cheap aerogels made
of clay; scale up from R&D to manufacturing underway
Source: Evacuated Panels Utilizing Clay-Polymer Aerogel Composites for
Improved Housing Insulation, Dalton et. al., 2010

25. Aerogels cost and performance
Improvements in performance of building insulation materials
 Thickness of insulation reduces while thermal conductivity falls
Source: Vacuum promises a thinner future, A.Birch, 2009

26. Improvements in Aerogels
Use of aerogels in many industries is driving improvements
 Wide applications across various industries
Source: J. Non-Crystalline Solids, Schmidt et al, 1998

27. Aerogels for Building Insulation
Potential Aerogel usage for Window insulation
Thermal Conductance, U value (W/m2K)
Insulation glass unit:
Clear Aerogel
Thermal transmittance for different insulations types of windows
Source: Aerogels Handbook, Springer, 2011

28. Maximizing day lighting
Using light ducts for lighting in offices
Source: Solar Energy Vol. 73, No. 2, pp. 123–135, 2002)

29. Solar chimney
Solar assisted stack ventilation
Use of natural convection to
supply fresh air:
 Under PV panels on rooftop
hot air accumulates
 Hot air is rising in chimney
(buoyance effect)
 Rising air generates suction,
removing old air in offices
 New (fresh) air introduced
from sidewalls
Source: BCA academy building, Singapore’s first ZEB

30. ZEB: State of the art and outlook

31. Case Study: BCA Academy, Singapore
Singapore’s first ZEB (retrofitted to existing building)
Insulation • Low-absorption
glass
(1,2,3) • Green walls/roofs
5 • Meets annual
energy demand
4 3 BIPV
• PV on roof, facade,
(4,5,6) car park
1
7 • c-Si and thin film
2
6 • LEDs, motion
sensors (6)
Lighting • Light ducts,
(7) reflecting panels
(maximising day
lighting)

32. PV, closer look
Solar chimney
Facade PV
Roof PV
Roof PV
Thin film PV on
car park shelter
Source: BCA Academy ZEB website, virtual tour

33. Passive design, closer look
Green Roof
Insulation on glass
Sun shades with PV
Motion
Green Walls sensors Light duct
LED
Reflecting
panels
Source: BCA Academy ZEB website, virtual tour

34. Case Study: BCA Academy, Singapore
Energy production, consumption and cost saving (Oct 09 – Jan 12)
Cumulative energy Typical office
879350 kWh
consumption of similar layout
Cumulative energy
424830 kWh
consumption
ZEB, BCA Academy
Cumulative energy
454958 kWh
production
Cost saving due to energy efficiency S$ 118,410
Cost saving due to onsite energy generation S$ 112,237
Source: BCA Academy ZEB website, Energy Production and Consumption, 2012

35. Customer needs
The ZEB approach and drivers for improvement
Economy Comfort
• Approach: Upfront cost offset by • Approach: Energy efficient HVAC,
low operating cost smart lighting etc
• Drivers: Advances in energy • Drivers: reduction in cost, more
generating/saving components widespread information
ZEBs
Functionality Aesthetics
• Approach: Smart design • Approach: Alternative building
• Drivers: Architectural expertise materials
specific to ZEBs • Drivers: Architectural expertise
specific to ZEBs

36. Market prediction for ZEBs
Analysis of US construction market
 Pike Research: ZEBs market
$690 billion by 2020
 Market share for:
 Architecture, engineering
and construction firms
(“zero energy design”)
 PV and other renewable
energies
 HVAC, lighting and others
 Building materials
Source: Pike Research Report on ZEBs, 2011 and Green outlook, McGraw-Hill Construction, 2011

37. Thank you for your attention