net-zero energy case studies
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Architect-Engineer Services Master Planning and
Design
for 10-year Development at Central Utility Facility
(CUF)
OC Public Works/Facilities and Real Estate ManagementProject Management
Presentation for Gulf Coast Green 2013
Net Zero Energy Case StudiesScott WestMechanical EngineerMay 2, 2013
Best Practice
Jacobs is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES). Credit(s) earned on completion of this program will be reported to AIA/CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon request.
This program is registered with AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product.
Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.
Course Description
• This session will focus on design and implementation of net zero energy buildings and how they can be turned into an operational reality. Achieving net zero energy buildings is the adopted goal of the AIA 2030 commitment and is often viewed as the standard for climate neutrality for new buildings. Net zero energy buildings offer particular design challenges but are possible in many circumstances with current technology.
Learning Objectives
• Cover the various definitions of net zero energy and how they apply to high performance projects
• Learn how integrative design can help achieve project energy goals
• Review net zero energy case studies and share lessons learned
• Evaluate the economics of net zero energy building design and construction
Why Are We Concerned With Net Zero Energy?
• Energy security
• Resource conservation
• Reduce operating cost
• Mitigating climate change
• Local environmental impact reduction
• Hedge against future energy price volatility
Recent Energy Legislation and Federal Leadership in Green Building Practices
• EPAct 2005, EISA 2007, EO 13423, EO 13514, Federal Leadership in High Performance and Sustainable Buildings
• EO 13514 from Oct. 2009 states in Section 2.g.i: “beginning in 2020 and thereafter, ensuring that all new Federal buildings that enter the planning process are designed to achieve zero-net-energy by 2030”
DoD and DOE Partner Up
• In 2008 DoD and DOE launched initiative to support net zero energy military installations
• Launched collaborative pilot of Marine Corps. base at Miramar
• NREL has helped out with NZEI guidance so far
• All US military branches addressing net zero energy to varying degrees
AIA 2030 Challenge
ASHRAE Path to Net Zero Energy
Net Zero Energy Definition
Type Description
Net Zero Site Energy The boundary is the site and the energy is measured annually at the utility meters
Net Zero Source Energy The energy is valued at its point of extraction (e.g. the wellhead or the coal mine)
Net Zero Energy Cost The credits received on exported energy equals the amount of annual energy bills from utilities
Net Zero Energy Emissions The emissions from fossil fuel energy use are offset by renewable energy fed into the grid on an annual basis
NREL Paper Goes Into More Depth on Definition
Site-Source Energy Factors
• NREL – Source Energy & Emission Factors for Energy Use in Buildings – June 2007
Net Zero Energy Definition
• Source versus site energy
• On-site combustion versus all electrical
• Treatment of off-site renewable energy generation and carbon offsets
• Campus setting versus treatment of individual buildings
• Treatment of embodied energy
• Division of responsibilities between owners, tenants and utilities
Federal Net Zero Energy Definition for DoD
Case Studies
University of North Texas – Net Zero Lab
Green Design Features
• Mixed mode ventilation with solar chimney
• Rainwater harvesting
• Solar PV and thermal
• Ground source heat pumps
• Radiant underfloor heating
and cooling
• Energy recovery ventilation
• Daylighting
Architectural Floor Plan
Underfloor Piping Zone Layout
They Built It!
University of North Texas – Net Zero Lab
Little Rock Air Force Base – C-130J Fuels Maintenance Hangar
C-130J: Super Hercules
Level 1 Layout
Level 2 Layout
C-130J Fuels Maintenance Hangar
• Net zero energy design definition»Includes plug/process loads»Based on site energy, gas use is okay if it is
offset on a per Btu basis»Transportation energy use not accounted for
• Challenges»FMH require high exhaust and make-up air flow
rates»90.1-2007 PRM requires an artificial cooling
system in the hangar (this has changed thankfully)
»Hangar infiltration is a big concern in heating season
YESYES
YESYES
YESYES
YESYES
YESYES
YESYES
YESYES
YESYES
YESYES
YESYES
MAYBE
MAYBE
MAYBE
MAYBE
MAYBE
MAYBE
NO
NO
NO
NO
NO
NO
YESYES
NO
NO
ECM Table
Show Model Inputs for all Alternatives
Baseline (Appendix G)
Current Concept Design (Appendix G)
ZNE Proposed Design (Both)
Construction TypeU-value (Btu/h-ft2-F) SHGC
U-value (Btu/h-ft2-F) SHGC
U-value (Btu/h-ft2-F) SHGC
Wall-CMU 0.085 - 0.085 - 0.045 -
Wall - metal 0.085 - 0.085 - 0.0499 -
Roof 0.048 - 0.047 - 0.032 -
Lobby glazing 0.650 0.250 0.520 0.331 0.520 0.331
Translucent panels 0.650 0.250 0.140 0.190 0.050 0.150
Door -storefront 0.600 0.250 0.520 0.331 0.520 0.331
Door - Opaque 0.700 - 0.200 - 0.200 -
Door- non-swinging 1.450 - 1.450 - 1.450 -
Partition Wall 0.123 - 0.094 - 0.094 -
Space ClassificationCooling SADB
Heating SADB RH %
Admin Areas 76 68 50
Shops/Storage 76 68 50
Mech/Elect 85 55 50
Comms 75 75 50
Hangar Area (conditioned) 85 65 50
Hangar Area (unconditioned) 110 65 50
ECM Energy Savings
0 100 200 300 400 500 600 700
EC
M
Energy Savings (MWh)
Solar Thermal
Alternate Ventilation Method
Ground Loop - VRF in central core
Solar Hot Water Heater
Hanger Door Decreased Infiltration
Biomass Furnace for Hangar Heating
Air-cooled VRF in Central Core
Overhangs on Kalwall Panels
Increased Insulation
Exterior Lighting LED's
LED fixtures in the Central core area
Standard Kalwall Daylighting
Kalwall Aerogel+Daylighting
LED lighting in Hanger
ECM Bar Charts
ECM LEED % Savings
-1.00 0.00 1.00 2.00 3.00 4.00 5.00 6.00
EC
M
LEED Savings %
Solar Thermal
Alternate Ventilation Method
Ground Loop - VRF in central core
Solar Hot Water Heater
Hanger Door Decreased Infiltration
Biomass Furnace for Hangar Heating
Air-cooled VRF in Central Core
Overhangs on Kalwall Panels
Increased Insulation
Exterior Lighting LED's
LED fixtures in the Central core area
Standard Kalwall Daylighting
Kalwall Aerogel+Daylighting
LED lighting in Hanger
ECM Bar Charts
Be sure you know your project goals
Total Energy Use - Appendix G Models
0
200
400
600
800
1,000
1,200
1,400
1,600
En
erg
y U
se
(M
Wh
)
Current Concept Design
NZE Proposed Design
% Improvement over Baseline - Appendix G Models
20
25
30
35
40
45
50
55
60
65
70
% Im
pro
vem
ent
Current Concept Design
NZE Proposed Design
Annual Energy Costs - Appendix G Models
0
20,000
40,000
60,000
80,000
100,000
120,000
140,000
160,000
180,000
200,000
Baseline (AppendixG)
Current ConceptDesign (Appendix G)
NZE ProposedDesign (Appendix G)
En
erg
y C
os
ts (
$) Domestic Hot Water
Heating - Gas
Heating - Electric
Fan Equipment
Cooling Equipment
Process Loads
Lights
Presenting Overall Energy Results
Renewable Energy Options
Solar PV Array
Lessons Learned
Look for the Sweet Spot
• Delivers the ideal result for clients’ pocket books, the environment and society
ECONOMYECONOMY SOCIETYSOCIETY
ENVIRONMENTENVIRONMENT
Sustainable Development
(the ‘sweet spot’)
Viable
Bearable
Equitable
Integrated (Integrative) Design Process
Conceptual Project Planning
Design Team
Design Team
City / CountyCity /
County
Building Owner
Building Owner
Energy Consultant
Energy Consultant
Building OccupantsBuilding
Occupants
Cx
Agent
Cx
Agent
Project ManagerProject
Manager
Utility Company
Utility Company
3rd Party Engineers & Inspectors
3rd Party Engineers & Inspectors
MEP Engineers
MEP Engineers
Interior DesignerInterior
Designer
ArchitectArchitect
Landscape Architect
Landscape Architect
Sustainable design is most effective when applied at the earliest stages of design
The conceptual design process is a collaboration of several disciplines that effectively integrates all aspects of site planning, building design, construction, operations and maintenance
A Sustainability (Eco) Charrette is an
intensive workshop in which stakeholders
and experts come together to address
project sustainability issues
The Charrette should result in unified
sustainability, design and construction goals
for everyone to work toward
A Sense of Place
• Integrate the building with its surroundings
• Apply the most economical options to achieve the desired result (e.g. don’t install a wind turbine to look green that won’t be running most of the time!)
• Passive solar design should not be skipped over but should be balanced with functionality and aesthetics
NZE Hierarchy
NZE Design for Passive Measures
• There is an economical limit to insulation levels (diminishing returns)
• Limiting solar heat gain through high performance glazing or solar shading is paramount (especially in Texas!)
• If your local climate is amenable to natural ventilation, the architectural design should be accomodating to it, we have the tools now!
• Good daylight design is an iterative process and proper modeling time should be allotted
NZE Design for HVAC
• Variable refrigerant flow (VRF) – very cost-effective now compared to traditional systems
• Geothermal• Radiant heating/cooling• Displacement ventilation (and sometimes UFAD)
• Energy recovery ventilation – decouple space conditioning from ventilation load to improve effectiveness and control
• Use LED lighting where you can and use lighting controls wherever they will help, e.g. occupancy and daylight sensing
NZE Design for Renewables
• Solar PV – Very “plug-and-play” but account for placement and orientation, PPA is a popular vehicle for large installations, default NZE equalizer
• Solar thermal – EISA 2007 requirement for federal buildings, usually a no-brainer for NZE
• Transpired solar collectors – excellent for areas with simultaneous sunshine and heating hours
• Biomass – difficult to beat as a high quality heat source
• Wind – often very cost-effective but hub height must be high enough, very visible though
• Offshore wind and wave/current energy – good potential for coastal areas
NZE for Designers
• Form follows function instead of function following form, NZE is a performance target and deviating from this principle can torpedo an otherwise successful approach
• Integrated, coordinated approach: disciplines should not work in isolation, design changes can have effects all the way down the line
• Model energy use early and often
• Design with a “systems mentality”; like in nature all building systems are somehow connected, e.g. DHW on geothermal system, selection of material reflectances affects daylighting, etc.
NZE for Building Users/Owners
• Plug/process loads become 40% or higher of overall building energy use for NZE designs
• Occupant behavior’s effect on energy use becomes very significant, behavioral change is often necessary
• Emphasis on flexibility rather than recipe approach: Might have to revisit existing design standards and decisions in order to achieve goal of NZE
• Suggest energy sub-metering, EMS and dash-boarding to complete energy information feedback loop
• Expect to spend more time on conceptual design phases
Cost of Net Zero Energy
• Cost premium anywhere between 5% up to 25% or even higher
• Emphasis on delivering NZE economically
• Rigorous life cycle costing is crucial
• Implementing passive energy measures can often down-size HVAC equipment enough to save significant costs
• Spend time on careful cost estimation at various decision points: rules of thumb and $/sf estimates don’t work very well for NZE
Net Zero Energy Economics
• How effective is the energy reduction measure compared to PV?
• For the same amount of kWh saved from an ECM, how does it compare to the cost of PV to generate the same amount of kWh?
• This is often the cost inflection point between energy efficiency and renewable energy
Bibliography
1. US Army Vision for Net Zero: http://army-energy.hqda.pentagon.mil/netzero/
2. Architecture 2030 Challenge: http://architecture2030.org/2030_challenge/the_2030_challenge
3. ASHRAE; Report of the Technology Council Ad Hoc Committee on Energy Targets; June 2010
4. 7 Group, Bill Reed; The Integrative Design Guide to Green Building; 2009