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www.arpa-e.energy.gov
BUILDING ENERGY EFFICIENCY
Ravi Prasher, Technology Development Program Manager, Intel Corporation
Colin McCormick, Building Technologies Program, U.S. Department of Energy
March 1, 2010
ARPA-E Pre-Summit Workshop
www.arpa-e.energy.gov
“There is a growing realization that we should be able to build buildings that
will decrease energy use by 80 percent with investments that will pay for
themselves in less than 15 years. Buildings consume 40 percent of the energy
in the U.S., so that energy efficient buildings can decrease our carbon
emissions by one third.”
Secretary Chu, Caltech Commencement, June 12, 2009
VISION
Buildings use 72% of nation’s electricity and 55% of its natural gas.
Buildings construction/renovation contributed 9.5% to US GDP and employs
approximately 8 million people. Buildings’ utility bills totaled $370 Billion in 2005.
Source: Buildings Energy Data Book 2007
By 2030, Business as Usual
• 16% growth in electricity
demand
• Additional 200 GW of
electricity at cost of $500-
1000B, or $25-50B/yr
Buildings Can Provide
Grid-Level Storage
BUILDINGS PLAY A KEY ROLE IN
AMERICA’S ENERGY FUTURE
China
India
8.5%/yr growth
New: 80% reduction
Existing: 50% reduction
COMMERCIAL BUILDINGS OFFER A
SIGNIFICANT OPPORTUNITY FOR
ENERGY SAVINGS
• HVAC (space heating,
space cooling, and
ventilation): 31.4%
• Lighting: 14.1%
• Water heating: 8.6%
• Increasing
miscellaneous loads
• Air conditioning is a
key driver of peak
electricity demand.
Source: 2009 Buildings Energy Data Book
(http://buildingsdatabook.eren.doe.gov/TableView.aspx?table=1.1.5)
Space heating, 20.0%
Lighting,14.1%
Space cooling, 9.9%
Water heating, 8.6%
Electronics, 7.2%
Refrigeration, 5.2%
Wet clean, 3.1%
Computers, 2.7%
Cooking, 2.3%
Ventilation, 1.5%
Other,17.3%
Adjust to SEDS, 8.1%
Total: 41.0
Quads
TOTAL PRIMARY ENERGY
CONSUMPTION
BY BUILDINGS (2010)
• Buildings are
responsible for ~ 40%
of CO2 emissions in
the U.S.
• Buildings are
responsible for ~ 2,300
Tg CO2 eq. (MMT)
• Cooling alone is
responsible for ~ 5%
of CO2 emissions in
the U.S.
Source: 2009 Buildings Energy Data Book
(http://buildingsdatabook.eren.doe.gov/TableView.aspx?table=1.1.5)
TOTAL CO2 EMISSIONS BY
BUILDINGS
(2010)
Space heating, 447
Lighting, 336
Space cooling, 236Water
heating, 197
Electronics, 172
Refrigeration, 125
Wet clean, 73
Computers, 64
Cooking, 54
Ventilation, 35
Other, 405
Adjust to SEDS, 194
Total: 2,338
Tg CO2 eq.
Courtesy: World Business Council for Sustainable Development (WBCSD) Report
on Energy Efficiency in Buildings, July 2008
Need:
• Tools to integrate process & communities
• Tools to integrate building design and operations
• Align incentives
FRAGMENTATION OF INDUSTRY
AND PROCESS
SYNERGISTIC APPROACH
David Culler
University of
California,
Berkeley
Member of National
Academy of Engineering
Credited with pioneering
work on sensor networks &
computer architecture
Sanjay Sarma
Massachusetts
Institute of
Technology
Credited with developing
many standards and
technologies that form the
foundation of the commercial
RFID industry.
Sam Baldwin
DOE, Office of
Energy Efficiency
and Renewable
Energy
Chief Technology Officer and
Member, Board of Directors
Satyen Mukherjee
Phillips Research
Chief scientist and senior
director for research strategy
in North America
Ron Judkoff
National Renewable
Energy Laboratory
Director, Center for Buildings
and Thermal Systems
Jeff Snyder
California Institute of
Technology
Thermoelectric Materials
and Devices
Breakdown of 76 attendees
by affiliation
Representative Attendees
ARPA-E & EERE BUILDINGS
WORKSHOPDECEMBER 15, 2009
25%
26%30%
18%
National Labs Academia
IndustryFederal Agencies
DOE, DOD, NSF, NIST, GSA, OSTP
What is the state-of-the-art and where do we want to be?
What are the gaps, challenges, and barriers?
What are the potential approaches to overcoming the barriers?
What are the specific performance and cost metrics?
What is the time horizon for goals?
What are the challenges and barriers for validation and adoption?
What levels of investment do we need to develop and deploy these
technologies?
What is the return on investment?
KEY QUESTIONS
ACHIEVING EFFICIENT BUILDINGS IS VERY
CHALLENGING, BUT EXISTING EXAMPLES &
INVESTMENT AREAS PROVIDE HOPE
Dr. J Michael McQuade,
United Technologies Corp.
Buildings Systems Grand Challenges to Increase
Energy Efficiency
Greatest efficiency improvements may lie in
exploitation of otherwise detrimental sub-system
interactions
Efficient designs must also deal with uncertainties
and bottlenecks in design and operation
Investments are required to achieve aware,
interactive, reconfigurable buildings
WE SHOULD STRIVE TO BRIDGE THE TRADEOFF
THAT EXISTS BETWEEN ENERGY CONSUMPTION
AND PERFORMANCE
Yi Jiang
Tsinghua University
What is the approach to reach the low energy goal for
buildings?
There is a huge difference in building energy
consumption between OECD and developing
countries such as China
Difference due to lifestyle difference - energy
efficiency designs must take lifestyle into account
Decentralized, “part time part space” service
system may be the US solution
Other areas for study - independent control of
temperature and humidity, evaporative cooling
1. Measurement & Communication (sensors, data protocols, power)
• Shyam Sunder (NIST)
• David Culler (UC Berkeley)
2. Simulation & Computation (computational models, calibration)
• Ron Judkoff (NREL)
• Michael Wetter (LBNL)
3. Systems Approach to Fault Diagnostics and Controls
• Scott Bortoff (Mitsubishi Electric)
• Srinivas Katipamula (PNNL)
4. Active and Passive Thermal Devices and Components
• Ravi Prasher (Intel)
• Sam Baldwin (DOE/EERE)
BREAKOUT SESSIONS
Highly efficient buildings exist today, but measured performance rarely
meets design performance.
Achieving designed performance requires labor-intensive, high-skill
continuous operation & maintenance. This must be made easier.
Solution will be part technical, part behavioral, part economic, part policy.
Enormous opportunities exist in improved systems integration.
Investable areas for building science components include:
– Lighting (Solid State lighting program in EERE)
– Active building envelope technologies (controllable)
– Long-duration, fast-charging/discharging thermal storage
– Enhanced passive ventilation systems
– Fast humidity control systems
– High-efficiency, low-GWP refrigerant replacements/not-in-kind systems
KEY LESSONS
The SpreadEUI in kBTU/sq.ft.-yr
Analysis of 121 LEED-Rated BuildingsLow-to-Medium Energy Use Intensity Buildings
Measured to Design Ratio
Towards Zero-Net EnergyM. Frankel, “The Energy Performance of LEED Buildings,” presented at the Summer Study on Energy Efficient
Buildings, American Council of Energy Efficiency Economy, Asilomar Conference Center, Pacific Grove, CA, August
17-22, 2008.
Labels/codes are for Design Performance, NOT based on Measured Performance.
Gap
• Lack of Measurements & Policies
Requiring it
MISMATCH BETWEEN MEASURED &
DESIGNED PERFORMANCE
MEASUREMENT & COMMUNICATIONSENSOR PARAMETERS
Key parameters Future/desirable parameters
Mass flow (air, water, steam, fuel) Carbon dioxide
Temperature, pressure, humidity VOCs
Light levels Biologics
Electrical power (sub-metering major
equipment, tenant groups)
Occupant density
Indoor environmental quality Plug load power consumption
Building boundary conditions or
configuration (windows, doors, etc)
Granular equipment consumption (zonal)
Occupancy and comfort levels, acoustics Parameterized personal comfort
External conditions (weather, insulation)
Measurement Type I:Conservation Laws
Utility Line
Distributed
Use
Y
xi
Is Y = Σxi ?
Measurement Type II: Model Validation
Heat Loss
Heat Load
Inlet Outlet
Measurement ModelInverse
ForwardCalibrated
Model
People
,,TYm
,,TYm
,T
MEASURED PERFORMANCE IS
LINKED TO MEASUREMENT TYPE
MEASUREMENT & COMMUNICATIONSENSOR CHARACTERISTICS/BARRIERS
Key characteristics Key barriers
Sensor density based on gradients Sensor drift and mis-calibration
Location at equipment, exterior faces Large dataset handling (search, etc)
Ease of access/maintenance Inadequate meta-data
Dynamically configurable Connectivity (wired/wireless?)
Integration with controls Power (energy harvesting?)
Robust to single-point failure Interoperability
Fully autonomous Legacy systems, protocol changes (3-4 years)
Long sensor lifetime (20+ years?) Expense/difficulty of mesh network?
SIMULATION & COMPUTATIONSIMULATION NEEDS/CHALLENGES
Issues Needs
Modeling inefficient buildings is more difficult
than efficient ones
Tools/interface tailored to different
user groups
Occupant behavior in larger buildings is highly
stochastic
Fast/real-time simulation
Weather data is hourly – hard to simulate at finer
timescales
Ties into other toolsets (MATLAB,
Mathworks, etc)
Wind data is at a single elevation (10 m) – large
impact on buildings
Smooth transition from design
model to operating model
Moisture is not well-modeled Better inverse-modeling capability
Ground coupling is not well-modeled Better theory of in-building
convection
Equipment performance (esp. legacy) is not well-
modeled
Communicating anticipated loads
to utilities
SIMULATION & COMPUTATIONTIME AND LENGTH SCALES
Thanks to Michael McQuade, UTC
Reduce energy consumption by cooling equipment
Alternate refrigerants with GWP < 1
On demand local cooling
CHALLENGE: REDUCING GHG
EMISSIONS FROM SPACE COOLING
Standard residential A/C working fluid
is moving from R-22
(production/import ban starts in 2010)
to R-410A and other HFCs.
Standard vehicle A/C working fluid is
moving from R-12 (production/import
ban started in X) to R-134a.
R-410A 100-year GWP: 2,088.
R-404A 100-year GWP: 3,922.
AZ-20 (Honeywell)
Puron (Carrier)
Suva 410A (DuPont)
Forane 404A (Arkema)
Sources:
1) Velders et al, PNAS 106, 10949 (2009),
http://www.pnas.org/content/suppl/2009/06/22/0902817106.DCSupplemental/09028171
06SI.pdf#nameddest=ST2
2) EPA: http://www.epa.gov/Ozone/snap/refrigerants/lists/homeac.html
GHG EMISSIONS FROM HFC
WORKING FLUIDS
Under a 450-ppm stabilization
scenario, HFCs are likely to
contribute 28-45% of total GHG
emissions in 2050, on a CO2-eq
basis.
Growth is driven by demand for A/C
and refrigeration in the developing
world.
Source: Velders et al, PNAS 106, 10949 (2009),
http://www.pnas.org/content/suppl/2009/06/22/0902817106.DCSuppleme
ntal/0902817106SI.pdf#nameddest=ST2
HFC EMISSIONS: AIR CONDITIONING
& REFRIGERATION
CURRENT COOLING SYSTEMS
Cooling type COP Source
Air cooled systems ~4 EERE, DOE
Water cooled systems (evaporative
cooling of condensers)
~7 EERE, DOE
COP = Cooling load/ electrical energy supplied
Can we get COP same as water cooled chiller but without loss of water?
ENERGY END USE INTENSITIES IN
BUILDINGSTH1
TH2
BJ1
BJ2
BJ3
US2
FR1
SH1
US1
照明办公电耗kWh/m2.a
26.1 24.5 18.4 23.1 26.5
152.7 149.4
20.8N/A
0
50
100
150
200
TH1 TH2 BJ1 BJ2 BJ3 SH1 US1 US2 FR1
Lighting & appliances (kWh/m2.a)冷机电耗kWh/m2.a
8 6.59
19.526.7
13.7
48.152
43.97
22.2
0
10
20
30
40
50
60
TH1 TH2 BJ1 BJ2 BJ3 SH1 US1 US2 FR1
Chiller (kWh/m2.a)
风机电耗kWh/m2.a
0 7.7 0 8.121.5
168.7197.1
13.525.7
0
50
100
150
200
250
TH1 TH2 BJ1 BJ2 BJ3 SH1 US1 US2 FR1
Fan for AC system (kWh/m2.a)水泵电耗kWh/m2.a
02.9
0
8.96.4
25.3
17.519.5
9.8
0
5
10
15
20
25
30
TH1 TH2 BJ1 BJ2 BJ3 SH1 US1 US2 FR1
Pump for AC system (kWh/m2.a)
耗冷量GJ/m2.a
0.07 0.12 0.18
0.44
0.20
1.041.12
0.63
0.36
0.0
0.2
0.4
0.6
0.8
1.0
1.2
TH1 TH2 BJ1 BJ2 BJ3 SH1 US1 US2 FR1
Cooling (GJ/m2.a) 耗热量GJ/m2.a
0.28 0.30.2
0.3650.25
0.82 0.88
0.45
0.17
0.0
0.2
0.4
0.6
0.8
1.0
TH1 TH2 BJ1 BJ2 BJ3 SH1 US1 US2 FR1
Heating (GJ/m2.a)
USA USA
China
France
Courtesy: Yi Jiang, Tsinghua University
the Building's Cooling Electricity Consumption with
Different Operations in Shanghai21.8
12.4
8.8
5.33.3
0
5
10
15
20
25
Standard Case Raise the
Starting
Temperature
Open
Windows
Part Time
Operation
Part Space
operation
Co
oli
ng
Ele
ctri
city
Co
nsu
mp
tio
n o
f th
e
Wh
ole
Yea
r(kW
h/m
2·a)
HOW BUILDINGS ARE OPERATED IS
IMPORTANT
Comparing with the energy
consumption of the five cases– Total cooling electricity
consumption:
21.8kWh/m2 to 3.3kWh/m2!
Measured data & simulation
data in Beijing
0123456789
101112131415
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
住户编号
空调能耗指标
(kW
h/m
2)
平均值 2.3 kWh/m2 Average 2.3kWh/m2
En
erg
y C
on
sum
pti
on
of
Co
olin
g S
yste
m
(kW
h/m
2)
Apartment No.
0123456789
101112131415
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
住户编号
空调能耗指标
(kW
h/m
2)
平均值 2.3 kWh/m2 Average 2.3kWh/m2
En
erg
y C
on
sum
pti
on
of
Co
olin
g S
yste
m
(kW
h/m
2)
Apartment No.
Ele
ctri
city
Co
nsu
mp
tio
n o
f C
oo
ling
Sys
tem
0123456789
101112131415
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
住户编号
空调能耗指标
(kW
h/m
2)
平均值 2.3 kWh/m2 Average 2.3kWh/m2
En
erg
y C
on
sum
pti
on
of
Co
olin
g S
yste
m
(kW
h/m
2)
Apartment No.
0123456789
101112131415
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
住户编号
空调能耗指标
(kW
h/m
2)
平均值 2.3 kWh/m2 Average 2.3kWh/m2
En
erg
y C
on
sum
pti
on
of
Co
olin
g S
yste
m
(kW
h/m
2)
Apartment No.
Ele
ctri
city
Co
nsu
mp
tio
n o
f C
oo
ling
Sys
tem
the Building's Cooling Electricity Consumption with
Different Operations in Beijing
16.5
9.8
5.0
2.0 1.2
0
5
10
15
20
Standard
Case
Raise the
Starting
Temperature
Open
Windows
Part Time
Operation
Part Space
operation
Co
oli
ng
ele
ctri
city
co
nsu
mp
tio
n o
f th
e
Wh
ole
Yea
r(kW
h/m
2·a)
Cooling On Demand in
Space & Time
Courtesy: Yi Jiang, Tsinghua University
>10X
REHEAT FIGHTING WITH COOLING
A typical Air Handling Process in a US bldg: VAV + Reheat
22 ℃
17℃ 21℃ 14℃ 20℃
Cooling CoilVAV box withRe-heaterC ooling: 264kW
H eating: 228kW
22 ℃
17℃ 21℃ 14℃ 20℃
Cooling CoilVAV box withRe-heaterC ooling: 264kW
H eating: 228kW
Courtesy: Yi Jiang, Tsinghua University
HEATING & COOLING IN AN USA
CAMPUS IN PHILADELPHIA
2006年度UPENN逐月总冷量和热量
0
50000
100000
150000
200000
250000
7月 8月 9月 10月 11月 12月 1月 2月 3月 4月 5月 6月
GJ 冷量
热量
Heating and Cooling Load
0
20
40
60
80
100
120
140
160
180
200
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
MJ/m2
cooling load
heating load
Heating and Cooling Load
0
20
40
60
80
100
120
140
160
180
200
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
MJ/m2
cooling load
heating load
Courtesy: Yi Jiang, Tsinghua University
Waste
Latent load
Sensible load
THERMAL LOADS ON A/C
Reduction of temperature and humidity
Two types of loads
– Sensible load: mCp (Tamb – Tspace)
– Latent/humidity load: mhfg (xamb-xspace)
m = mass flow rate of air
Cp = specific heat of air
hfg = latent heat of water
x = humidity ratio (mass of water
vapor/mass of air)
Minimum theoretical work required to go from 1 to 2 = Availability
(exergy) of moist air
Sensible load
Latent load
Reheat load Extra cooling load
SEPARATE CONTROL OF HUMIDITY
& SENSIBLE LOAD
Which is a more energy efficient path?
DESICCANT SYSTEMS
BACKGROUND ON DESICCANTS
Desiccants material that absorb moisture:
During moisture adsorption/absorption (sorption)
– Latent is converted to sensible heat: Water vapor converts to liquid
– Heat is released due to sorption (typically small compared to L to S
conversion)
– Therefore process ~ isoenthalpic
During desorption in the regeneration of moisture to atmosphere
– Regeneration energy = sum of
• Latent heat
• Heat necessary to raise the desiccant to a temperature high
enough to make its surface vapor pressure higher than that of
surrounding air
– Desorption rate (r) = A*exp (-Ea/kBT): Arhenius Rate
Extra energy needed to to desorb the desiccant
amb
PvaporambambPvapor
amb
PairambambPairsT
TcTTTcx
T
TcTTTcw ln)(ln)(
ambvapor
vapor
ambvapor
ambvapor
vapor
ambairlP
PTxR
PP
PPTRw
__
lnln
MINIMUM THEORETICAL WORK FOR
AIR CONDITIONING OF MOIST AIR
Mina, Newell,& Jacobi, Int. J. Refrigeration, 28. 784 – 790 (2005)
For sensible or mechanical cooling (Carnot)
For dehumidification or latent load cooling (Entropy of mixing):
Availability (Exergy)
~ 60 – 120 oC
~500 oC
CarnotWs
Q1
Tamb
Thot
COPlatent Ql
Qd
Ql
Wl /Carnot
Ideal COPlatent = ~ 2.5-6.5
Real COP = ~ 0.7 – 1.0
Sensible HeatLatent Heat
IDEAL SYSTEM AT THERMODYNAMIC
LIMIT
Difference between current energy input and ideal system can be reduced by 50% by
•Increasing the COP of vapor compression (without loss of water!)
•Increasing the COP of the desiccant
REAL SYSTEMS VS. THEORETICAL
LIMIT
Current
systems
FOA
targets
Primary energy use
0
20
40
60
80
100
120
140
160
180
200
1 2 3 4 5 6 7 8
COP_Vapor-compression
Pri
mary
En
erg
y (
kJ/k
g)
Vapor
compression/mechanical
cooling
Desiccant + Vapor compression
(COPlatent = 1.4)Theoretical limit
Current
Systems
Tamb = 90 oF, RH = 0.9
Tsupply = 55 oF, RH = 0.5
Pri
ma
ry E
ne
rgy (
kJ
/kg
)
COPvapor-compression
REFRIGERANTS WITH GLOBAL
WARMING POTENTIAL (GWP) ≤ 1
Magnetic
refrigerants
Thermoacoustic
refrigeration
Thermoelectric
refrigeration
Is it possible to get 1 Ton (3.5 kW) of cooling with COP >4?
Recommended