Hugh Crowther presented Net Zero Energy Buildings at the November Illinois ASHRAE Chapter Meeting.

1. Net Zero Energy Buildings
Hugh Crowther P. Eng.
Director at Large

2. Agenda
• Climate Change
Statistics
• Government Policy
• NZEB definitions
• Practical Limitations
• ASHRAE Activity Oberlin College
• Examples Goal of net zero site energy use
• Next Steps

3. CO2 Levels

4. CO2 Emissions

5. Per Capita CO2 Emissions
• World; 4.3 metric tons/person
• OECD Nations; 11 metric tons/person
• USA; 19 metric tons/person
Global CO2 Emissions
2009: 30 Billion metric tons
2030: 42 Billion metric tons

6. Pre-industrial CO2 Levels
• Pre-industrial:
180 - 280 PPM
• 2007: 380 PPM
• 2050 Business as
usual: 580 PPM

7. International Policy
• Kyoto Protocol
– USA never ratified
– Minimal effect
• Copenhagen Accord
– USA 17% by 2020
– Not ratified
– No clear path to
implementation

8. Policy Makers
• Climate change
issues well known to
policy makers
– NGOs (NRDC) are
very vocal
• Most solutions are
painful to public
officials
They also know…

9. Energy Usage
Energy Use by Sector Electricity Use by Sector
Transportation
29% Residential
22% Other
28%
Industry Commercial Buildings
30% 19% 72%
Source: Energy Information Administration 2009

10. Renewable Energy

11. EISA 433
New Federal Building Targets
EISA 433
Against 2003 CBECS
(EUI – 91.00 Kbtu/ft2.yr)
Year Reduction EUI
2010 55% 40.95
2015 65% 31.85
2020 80% 18.20
2025 90% 9.10
2030 100% 0.00

12. EPA
• Treating CO2 as an
environmental risk
• Trying to manage it
through regulation
– Doesn’t require
congress
• Republicans moving
to limit EPA authority

13. Policy Makers and the Built Environment
• Strong focus on energy
use in buildings
– EISA 433
• Energy Bill/Climate
Change legislation that
focuses on energy
reduction in buildings
– Stalled right now
– States are now taking action
• They have learned how to
spell NZEBs!
They don’t know what it means!

14. Response to Policy
• Lots of organizations
moving to “High
Performance
Buildings”
• Public commitments
when NZEBs will be a
reality
– 2030 most common

15. ASHRAE Vision 20-20
36000
En rg ( B tu/yr)
e y k
Standard 90.1
AEDG
Standard 189
2010 2015 2020 2025 2030
Year

16. What is a Net Zero Energy Building?
• Conceptually, a building that has no
adverse energy [or environmental] impact
[because of its operation]
• ZERO is not easy to define!
– Disconnect all utility interfaces?
– Net energy transfer across boundary?
– Where is the boundary?

17. What is a Net Zero Energy Building?
• A building that over a period of time (typically a
year) will produce as much energy as it
consumes
– There will be on site power generation
• NZEB buildings should have very low EUIs and
then use on site power generation to reach zero
• There is no consistent definition!

18. Energy Use Intensities (EUI)
• EUI = Annual Bldg Energy Use/Floor Area
• Many definitions of EUI!
• Gross floor area?
• Rentable?
• Parking garages in or out?
• Consider 2 identical buildings
– One has a parking garage the other is attached to a
subway station
– If garage included in EUI, the building that promotes
automobile use will have a better EUI!

19. EUI Definition
• Denominator doesn’t have to be area
– Energy/person?
– Data packets/energy?
• Numerator even more interesting!
• Energy measured at site or source?
• Energy content (kWh) or energy cost ($)?
Std 189.1 Std 90.1

20. Net Zero Site Energy
• Measured at the interface of the building to
the utility (point of sale)
• Easy to measure/verify (kWh)
• Can favor electricity over on-site combustion
– Gets the utilities “engaged”
• Encourages energy efficient designs at the
building level
• What is the “site?” Building footprint or
property

21. Net Zero Source Energy
• With current information, really
just site with multipliers for
different fuels
• Has a grid (more global) impact
• Depends on dispatch of power
generation
– Fuel source
– Incremental dispatch
• Daily and seasonal dependencies
• Regional (non climatic) dependencies
• Not a strong focus on building efficiency

22. Net Zero Energy Cost
• What the owner really sees ($)
• (Also) based on site measurements
• Easy to verify
• Demand component
• High regional variations
• Highly dependent on rate structures (demand
and fixed charges cannot be negated)
• Cost volatility
• Market driven comparisons
• Cannot do this on a large scale

23. Net Zero Emissions
• Also based on site numbers, typically with
national or regional multipliers based on
generation location
– Carbon
• Same issues as source
• If a building has zero source energy and
therefore zero emissions, is it really a zero
emissions building?

24. Site vs. Source and Behavior
• Use site energy for a building in Minneapolis Mn.
that requires perimeter heating
– Promote electric BB over nat. gas boiler
• Use source (carbon) and the gas boiler will be
promoted
• Use source energy and a building can be
improved by buying “green” energy rather than
improving the building

25. Current Programs
Document Term Energy Considered Area
ASHRAE Std 90.1, Chapter 11 Modeled annual energy cost Site Gross
ECB
California Title 24, Part 6, Modeled annual energy costs Time dependent valued site Conditioned Floor area
Performance Method using time-dependent valued energy
(TDV) energy.
Arch 2030 Annual fossil fuel based energy Site fossil fuel Same as CBECS and Energy Star
2
in kBtu/ ft -yr
Energy Star Annual energy in kBtu/ ft²-yr Site and Primary (Source) Gross Building Floor Area
EISA 433 Annual fossil fuel generated Site fossil fuel Gross Building Floor Area
energy in kBtu/ft²-yr.

26. Current Programs
ZEB Goals by Organization
Site EUI
(kBtu/ft2)
120
CBECS
100
1999 CBECS
80
ASHRAE Energy Codes 50% Savings
from CBECS
60 ASHRAE 90.1-1999
ASHRAE 90.1-2004
40% Savings from
40 30% Savings from ASHRAE 90.1-2004
ASHRAE 90.1-1999
20
AIA 2030
DOE ZEB ASHRAE AEDG
0
1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025 2030
Year

27. ASHRAE EUI Definitions
• Efficiency Only Energy Use Intensity (EUI):
the Target Energy Use divided by the Gross
Floor Area measured in kBtu/ft2-yr.
– Focus on this value and you will drive energy
conservation
• Net Energy Use Intensity (NEUI): the Net
Energy Use divided by the Gross Floor Area
measured in kBtu/ft2-yr.
– This will be zero for NZEB

28. ASHRAE EUI Definitions
• Gross Floor Area: the sum of the floor areas of all the
spaces within the building, including halls and other
circulation areas, any common areas, basements,
interior shafts (by floor), mezzanine and intermediate-
floored tiers, and penthouses with headroom height of 90
in. (2300 mm) or greater; it is measured from the exterior
faces of exterior walls or from the centerline of walls
separating buildings, but it excludes covered walkways,
open roofed-over areas, porches and similar spaces,
pipe trenches, exterior terraces or steps, chimneys, roof
overhangs, parking garages, surface parking, and similar
features

29. Net Energy Use Intensity

30. ASHRAE Definitions are Not Perfect
• Don’t deal with site to source energy issues
• Don’t deal with customer who wants (needs) to
buy alternative energy off site

31. Are NZEB possible?

32. NZEB and IEQ
• NZEB cannot be
created at the
expense of
occupancy comfort
and safety
• Need to meet Std
62.1, Std 55 etc

33. Are NZEB possible?
Science House, Science Museum of Minnesota
goal: zero net site energy use

34. NREL Assessment of NZEBs
• Using ASHRAE
definitions
• Assuming 50% roof can
be PV
• Technology that is
available or nearly
available in the market
place
• 15 building types and 16
climate zones

35. NET EUI, Max Tech, No on site
Building Types Climate Zones
Climate Zone
All 1A 2A 2B 3A 3B 3C 4A 4B 4C 5A 5B 6A 6B 7
All 40.3 55.2 41.8 44.4 48.1 37.1 44.6 38.8 28 32.7 41.9 36.2 37.6 35.2 35.5
Office/professional 32.7 33.8 35.9 31.7 30.3 30.3 29 34.2 37.6 30.5 33.1 28.5 31 29 34.7
Nonrefrigerated warehouse 17.4 14.3 13.4 a 14.9 14.5 12 17 21.8 13.8 19.4 21.9 20.6 18.5 20.8
Education 23 74.5 26.6 30.9 19.9 21.6 27.1 25.6 17.4 18.8 21.6 18.6 22.4 23.8 27
Retail (excluding mall) 28.6 22.5 33.3 38.7 26.1 25.6 24.8 27.7 24.7 a 29.3 29.7 30.9 33.5 35
Public assembly 30.4 53.1 36.3 a 38.4 31.8 25.6 26.7 21.1 39.2 29.4 26.4 29.9 27 26.8
Service 37.1 72.6 41.7 a 28.7 31.5 22.2 38.4 26.6 a 40 34.2 34.4 34.6 41.6
Religious worship 16.4 a 17.2 a 11.9 12.8 a 16 21.4 a 18.6 13.1 19.1 13.7 a
Lodging 28.8 36.3 30.7 a 29.5 25.7 a 29.4 30.2 29 28 26.7 27.4 28.1 27.7
Food services 311.3 482.1 298.1 a 316.6 334.4 304.3 304.6 A 401.1 316.3 293.1 306.1 198.3 291.7
Health care (inpatient) 71.3 78.2 74.9 79.8 68.8 72 68.5 67.9 60.9 a 77.2 70.3 65.3 64 95.4
Public order and safety 43.7 a 38.7 a 35.9 51.5 a 37.8 a a 49 59.2 44.1 60.8 a
Food sales 107.1 a 112.3 a 118.5 94 98.6 112.7 a a 101.7 109.9 106.2 a 100.6
Health care (outpatient) 40.4 36.8 52.8 a 39 59.5 a 33.5 34.3 a 42.4 33.2 34.1 34.1 46
Vacant 11.6 a 6 28.3 13.3 10.1 8.3 16.3 16.6 6.3 7.3 7.7 14.2 a 28.2
Other 30.9 a 45.4 a 23.6 29.7 a 32 12.5 a 31.8 22.8 30 34 21.8
Skilled nursing 86.8 a 93.5 a 85.4 77.3 a 95 a a 93.4 68.8 75.3 74 a
Laboratory 286.3 a A a 296.9 318.7 a 227.3 a a 285.6 a 243.1 274.8 a
Refrigerated warehouse 51.1 a a a a a a 52.5 a a 51.4 43.3 52.5 a a

36. NET EUI, Max Tech, No on site
Climate Zone
All
All 40.3
Office/professional 32.7
Nonrefrigerated warehouse 17.4
Education 23
Retail (excluding mall) 28.6
Public assembly 30.4
Service 37.1
Religious worship 16.4
Lodging 28.8
Food services 311.3
Health care (inpatient) 71.3
Public order and safety 43.7
Food sales 107.1
Health care (outpatient) 40.4
Vacant 11.6
Other 30.9
Skilled nursing 86.8
Laboratory 286.3
Refrigerated warehouse 51.1

37. NET EUI, Max Tech, with PV
Building Types Climate Zones
Climate Zone All 1A 2A 2B 3A 3B 3C 4A 4B 4C 5A 5B 6A 6B 7
All 12.2 19.8 7.4 9.4 13.4 2.9 27.3 13.6 NZ 15.5 18.5 1.5 13.9 NZ 12.7
Office/professional 14.2 17.9 12.3 NZ 8 7 23 18.9 20.6 19.5 17.1 4.4 12 NZ 15
Nonrefrigerated warehouse NZ NZ NZ NZ NZ NZ NZ NZ NZ NZ NZ NZ NZ NZ 2.9
Education NZ 36.5 NZ NZ NZ NZ 1.8 0 NZ NZ 2.1 NZ 0.3 NZ NZ
Retail (excluding mall) NZ NZ NZ NZ NZ NZ 4.3 NZ NZ NZ NZ NZ 1 NZ 2.1
Public assembly 1.7 NZ NZ a 8.6 NZ NZ 3.8 NZ 19.2 2.5 0 8.2 10.7 NZ
Service NZ 19.7 NZ a NZ NZ NZ 5.6 NZ a 6.6 NZ 0.1 NZ 6.8
Religious worship NZ a NZ a NZ NZ a NZ NZ a NZ NZ NZ NZ a
Lodging 14.1 25.7 18.1 a 10.9 3.8 a 17.4 23.5 7.9 16.9 0.4 14.6 NZ 9.7
Food services 276.2 425 255.7 a 277 288.6 287.5 272.8 a 356.7 288.3 254.4 278.2 151.2 253
Health care (inpatient) 61.1 68.5 64.1 71.9 54.7 61.5 50.5 58.3 54.1 a 70.9 51.9 56.1 52.5 88.7
Public order and safety 20.1 a 18.4 a 1.1 20.9 a 18 a a 27.5 20 18.7 48.7 a
Food sales 66.7 a 66 a 71.8 45.6 58.8 72.1 a a 64.7 74.9 68.1 a 77.2
Health care (outpatient) 11.7 10.4 13.1 a 1 19.9 a 8.7 NZ a 21.3 NZ 11.5 8.1 26.6
Vacant NZ a NZ NZ NZ NZ NZ NZ NZ NZ NZ NZ NZ a 14.8
Other NZ a 2.9 a NZ NZ a NZ NZ a 4.4 NZ 7.9 NZ NZ
Skilled nursing 61.5 a 65.4 a 54.4 30.9 a 75.7 a a 73.9 21.9 55.6 34.7 a
Laboratory 272.9 a a a 290 286.4 a 205.9 a a 274.2 a 234.4 261 a
Refrigerated warehouse 15.6 a a a a a a 11.2 a a 31.9 1.1 16.8 a a

38. NET EUI, Max Tech, No on site
Climate Zone All
All 12.2
Office/professional 14.2
Nonrefrigerated warehouse NZ
Education NZ
Retail (excluding mall) NZ
Public assembly 1.7
Service NZ
Religious worship NZ
Lodging 14.1
Food services 276.2
Health care (inpatient) 61.1
Public order and safety 20.1
Food sales 66.7
Health care (outpatient) 11.7
Vacant NZ
Other NZ
Skilled nursing 61.5
Laboratory 272.9
Refrigerated warehouse 15.6

39. Percent of floor area able to reach ZEB goal
0
10
20
30
40
50
60
70
80
90
100
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40. Current Status
Site EUI kBtu/ft2-yr (MJ/m2-yr)
100.0 (1,135)
90 (1020) Existing commercial buildings (2003 CBECS)
79.2 (900) Models of existing stock (Griffiths et al. 2007)
75.0 (852)
70.7 (803) New buildings base scenario (90.1-2004)
50.0 (568)
40.3 (458) Max Tech energy efficient scenario
25.0 (284)
12.2 (139) Max Tech energy efficient scenario w/ PV
0.0
0 (0) Net Zero Energy Building

41. On Site Power Generation vs. Grid

42. Utility Base Load
Base
Load
Myers 2010

43. Myers Study (2010)
• Using Flex factor = 60% (40% based load)
– Up to 20% of annual electric energy could be met with
PV
– Would require rated capacity of PV be 4 times utility
peak demand
• Simply said, the utilities cannot have every
NZEB putting power on the grid at the same time
– Not only will the utilities not pay for the power, they
will not even take it!

44. NZEB Possibility
• It can be done for many building types in many
zones
– But not all
– Restaurants and health care and labs are not
possible
• Analysis assumes technology will arrive in the
next 20 years
• That money is no object
– Money is always an object!
• Considering the national building stock and
location, national NZEB is not possible
– Must be careful with “national policy statements”

45. NZEB Possibility
• 80% of the buildings that will be around in 2030
exist today
– Need an amazing strategy for existing buildings
• Need to deal with Utility base loading issue
• Even if we could only get half way there that
would be
– 20% reduction in energy usage
– 35% reduction in electricity usage

46. ASHRAE NZEB Activities
• Energy Target (ET) Committee
– Prepared the first report in 2010
– Now focusing on implementing 4 strategies
• Don’t set hard targets for 90.1 and 189.1
• Get help and keep going with AEDGs to NZEB
• Complete/update research for NZEB for all building types
and locations
• Educate the market place on what is and is not possible

47. ASHRAE Energy Labeling Building eQ Program

48. Advanced Energy Design Guides
• 30% set complete
– Schools
– Healthcare
– Small office
– Highway lodging
– Retail
• 50% series underway
– Small/med office Spring
2011
– K-12 School fall 2011
– Trying for Healthcare or
retail late 2011 or early
2012

49. Building Performance Metrics
• Published Building
Performance Metrics
• High performance
research
• New standards

50. Defining Scales
Max. Potential
90.1-1999 50% AEDG
“Carnot”
30% AEDG Zero Site
• All based on simulation

51. High Performance Buildings
• www.highperformancebuildings.gov
• Data base of high performance buildings
• 120+ in database
• Following have NEUI ≤ 0
– Aldo Leopold Legacy Center, Wi
– Challengers Tennis Club, Ca
– Environmental Tech Center-Sonoma, Ca
– Hawaii Gateway Energy Center, Hi
– ORNL, Tn
– Oberlin College, Oh
– Omega Center, NY
– Science House, Mn

52. NZEB House Case Study
Daily and Cumulative Net Electricity Use
February 2006 - March 2007
25.00 2500.00
20.00 Daily Net Use 2000.00
(A negative number indicates net
15.00 Cumulative Net Electricity Used 1500.00
Cumulative net kWh used
10.00 1000.00
Daily net kWh used
production)
5.00 500.00
0.00 J 0.00
-5.00
Blizzards -500.00
-10.00 -1000.00
-15.00 -1500.00
-20.00 -2000.00
-25.00 -2500.00
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53. NZEB Case Studies
• Oberlin College Lewis
Center (2000)
– Oberlin Oh
• Net zero site energy use
• 13,950 ft²
– $535/ ft²
• 59 kW solar array
• Geothermal
• EUI = 32.94 kBtu/ ft² Article in High Performance
• NEUI = - 0.52 kBtu/ ft² Buildings
Winter 2011

54. NZEB Case Studies
• Zion Visitor Center
(2000)
– Springdale Ut
• 70% energy cost
savings
• 7,600 ft²
• Evaporative cooling,
PV
• EUI = 44 kBtu/ ft²
• NEUI = 39.3 kBtu/ ft²

55. NZEB Case Studies
• Cambria Office
Center (2000)
– Ebensburg, Pa
• 66% energy cost
savings
• 34,500 ft²
• Geothermal, 14.3 kW
PV
• NEUI = 41.9 kBtu/ ft²

56. NZEB Case Studies
• Chesapeake Bay
Foundation (CBF)
(2000)
– Annapolis, Md
• LEED Platinum
• 32,000 ft²
• NEUI = 37.1 kBtu/ft²

57. NZEB Case Studies
• Thermal Test Facility
(TTF) (1996)
– Golden Co
• 70% energy cost
savings
• 10,000 ft²
• NEUI = 28 ktu/ft²

58. NZEB Case Studies
• Science House,
Science Museum of
Minnesota (2003)
– St Paul, Mn
• 0 net site energy use
• 1,530 ft²
• Geothermal, PV
• NEUI = 0 kBtu/ft²

59. Case Study Results
100% Percent Net Source Energy Savings
90% Percent Net Site Energy Savings
80% Percent Site Energy Savings
Percent Energy Cost Savings
70%
Percent Savings
60%
50%
40%
30%
20%
10%
0%
Oberlin BigHorn TTF Cambria Zion CBF
simulated as-built vs. simulated basecase measured data vs. simulated basecase

60. Case Study Results

61. NZEB in the Future
• Buildings have a major role to play in
national energy policy
– Not everything is going to be NZEB but we
should try to get closer
• It is one thing to design a building, it is
another to commission and operate it
– Expect to see more activity around building
operation

62. NZEB in the Future
• Need to deal with existing building stock
• Need to deal with load vs. on site
generation timing
– Brief going to congress on energy storage
– Thermal storage most cost effective
• Regulation will play a role but market
forces are better!
– Federal gov’t will be slow to act
– State gov’t taking the lead

63. Questions?