NET ZERO ENERGY BUILDINGS
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Transcript NET ZERO ENERGY BUILDINGS
NET ZERO ENERGY
BUILDINGS
DR. CY YAVUZTURK, PH.D, C.E.M.
COLLEGE OF ENGINEERING ARCHITECTURE
AND TECHNOLOGY
DEPARTMENT OF MECHANICAL
ENGINEERING
BACKGROUND
Assistant Professor in Mechanical Engineering
Teach and Conduct Research in
Thermodynamics, Heat Transfer, Energy Engineering, HVAC,
Sustainable Design
Active Member of the American Society of Heating,
Refrigerating and Air Conditioning Engineers
(ASHRAE)
Chair of Solar Energy Utilization Subcommittee
Former Chair of Research of Geothermal Energy Utilization
Subcommittee
OUTLINE
An Overview of the Energy Consumption ‘Landscape’
in the US.
Significance of Energy Savings in Buildings
What is a Net Zero Energy Building (NZEB)?
Active and Passive Approaches to Net Zero
New Constructions and Retrofits
Primary Technologies
Design for NZEB
Conclusions
Resources
AN OVERVIEW
United States Consumed about 100 QUADs
(Quadrillion BTUs) of Energy in 2007.
100 QUADs = 100,000,000,000,000,000 BTUs
In Other Words
800,007,000,000 gallons (US) of gasoline
3,040,026,600,000 liters of gasoline
3,600,000,000 tons of coal
97,043,400,000,000 cubic feet of natural gas
29,307,100,000,000 kWh of electricity
AN OVERVIEW
Energy Consumption by Source (DOE Energy Data Yearbook 2007)
AN OVERVIEW
Where Do We Consume Energy? (DOE Energy Data Yearbook
2007)
AN OVERVIEW
Building Energy Consumption Distribution (DOE Energy Data
Yearbook 2007)
ENERGY SAVINGS IN BUILDINGS
Approximately 48 QUADs consumed in Buildings
36% Space Air-Conditioning -> 17.3 QUADs
27% Space Illumination -> 12.9 QUADs
14 % Water Heating & Refrigeration -> 6.7 QUADs
11 % Electronics & Computers -> 5.3 QUADs
2% Cooking -> 1 QUAD
10 % All Other Consumption -> 4.8 QUADs
Significant Opportunities in Reducing Energy
Consumption Exist!
1% Reduction = 0.48 QUADs
ENERGY SAVINGS IN BUILDINGS
0.48 QUADs = 480,000,000,000,000 BTUs
In Other Words
3,843,360,000 gallons (US) of gasoline
14,592,127,680 liters of gasoline
17,280,000 tons of coal
465,808,320,000 cubic feet of natural gas
140,674,080,000 kWh of electricity
However, Technology is available & Economics are
favorable to do more than reducing Consumption.
Reduction coupled with Production of Energy,
leading to Net Zero Energy Buildings.
JUSTIFICATION FOR NET ZERO
71% of All Electricity Consumed is Consumed in
Buildings! This is a Huge Burden on:
Electrical System
Energy Resource Availability
Emissions
Economic Viability
To make things worse:
The Commercial Sector is Expected to Grow by Average 1.5%
Annually in the next Decade
Economic Expansion and Population Growth Demands more
Building Space
Energy Demand is Growing faster than Energy Conservation
Measures taken.
JUSTIFICATION FOR NET ZERO
Consider the following (DOE 2006 Scenario):
The current stock of commercial buildings have an approx.
Energy Use Intensity (EUI) of about 85 kBTU/sqft
If all buildings in the commercial stock had been designed
using the Model Energy Code (ASHRAE Std. 90.1-2004), the
EUI would be about 50 kBTU/sqft
41% Energy Savings!
Tremendous Potential for Energy Savings Already Exits.
And, if PV were to be added to commercial roofs EUI may be as
low as 35 kBTU/sqft!
Add ‘Solar Energy Measures’, HVAC Equipment Efficiency
Improvements (mostly modest!) -> EUI further reduces to 15.5
kBTU/sqft
NET ZERO ENERGY BUILDINGS
GETTING CLOSER!
NET ZERO ENERGY BUILDINGS
BUT THERE IS SIGNIFICANT WASTE!
NET ZERO ENERGY BUILDINGS
ZERO is the Crossover Point between a Building
that consumes a Resource and one that produces the
Resource.
It is the point where Energy Needs of a Building has
No Impact.
Zer0 - Sum of All Energy Flows are Equal but
Opposite.
∑E=0
NET ZERO ENERGY BUILDINGS
Several Definitions (or ways of accounting) Exist:
Net Zero Site Energy Building – Produces as much
renewable energy as it uses in a year at the site.
Net Zero Source Energy Building – Produces (or
purchases) as much renewable energy as it uses in a
year when accounted for at the source.
Net Zero Energy Costs Building – Receives as much money
from the Utility Co. for on-site production of
renewable energy as it pays in a year for energy
services.
Net Zero Energy Emissions Building – Produces (or
purchases) enough emission-free renewable energy to
offset emissions from all energy used in a year.
NET ZERO ENERGY BUILDINGS
No ‘Best’, All-Encompassing Definition Exists!
Each Approach has Merits as well as Drawbacks
Goals of the Building Owner and Building Use
Characteristics also play a significant role as to what
approach may be the most reasonable.
However, one Rule remains constant for newconstructions and retrofits:
REDUCE DEMAND FIRST, SUPPLY SECOND!
PASSIVE APPROACH TO NET ZERO
Building Geometry and Orientation Measures
High-Performance Building Envelopes (Insulation,
Fenestration)
Passive Solar Heating/Cooling (Trombe Walls,
Fabric Cooling)
Day-Lighting
Natural Ventilation
ACTIVE APPROACH TO NET ZERO
High-Efficiency HVAC Equipment
Ground-Source Heat Pump Systems
Solar Thermal
Solar Photovoltaics
Wind Turbines
Ocean Water Cooling
Biomass Energy
Combined Heat and Power
Evaporative Cooling
OTHER APPROACHES TO NET ZERO
Thermal Energy Storage
Controls
NEW CONSTRUCTION & RETROFIT
Approaches to Net Zero will be different if New
Construction or Retrofit.
Some Technologies may be ‘too late’ for an already
existing building.
Nevertheless, with exceptions, the overall design
approach is fundamentally the same.
It’s all about judicious use of energy to reduce cost
and ‘save the planet’ in the process!
THE FUNDAMENTALS
A Building’s Energy Consumption can be broken
into:
Envelope Needs
Sensible Conduction
Solar Loads
Infiltration Loads (Sensible and Latent)
Occupant Needs
Sensible and Latent Needs
Fresh Outside Air Requirements
System Efficiencies
Mechanical Component Efficiencies
Configuration and System Control Strategies
THE FUNDAMENTALS
The Building Envelope:
THE FUNDAMENTALS
Internal Loads:
THE FUNDAMENTALS
Inefficiencies:
About 15%-20% of Energy Savings could be achieved in
Commercial Buildings if
Equipment Inefficiencies could be eliminated
System Configuration Improvements
System and Sub-System Operations could be optimized
Whole-Building system control and operation algorithms could be
implemented
And with some (even minor) attention to detail in the operation of
mechanical systems
DESIGN FOR NZEB
Building Envelope Measures
Orientation – optimize natural daylighting, passive solar heat
in winter & minimize solar heat gains through fenestrations
Increase R-values of walls and roof with enhanced envelope
insulation
External shading devices to minimize direct sunlight in
summer (fins, overhangs, plants)
Skylights for natural daylighting and monitors to bring
daylight into building core
Optimize envelope surface performance (reduce glazing areas
in E/W facing surfaces, increase in N/S)
DESIGN FOR NZEB
Equipment & Lighting Measures
High-efficiency lighting controlled with occupancy sensors
Daylighting controls to lower lighting and cooling
requirements
High-efficiency water heating systems to reduce stand-by
losses
Maximum use of outside air ventilation when outside
temperatures are low (free cooling)
Demand controlled ventilation with occupancy sensors
Ground source heat pump systems for higher COP’s
Variable speed fans and pumps to reduce energy distribution
energy at part load conditions
DESIGN FOR NZEB
Waste heat recovery
Evaporative cooling
Internal energy wheeling
Optimized controls
Occupant and operator training
DESIGN FOR NZEB
Renewable Energy Measures
Solar thermal collectors for service water as well as space
heating
Photovoltaic panels for direct electricity generation
Electricity generation from wind energy
Geothermal energy utilization
Biomass
Other renewable energy technologies as appropriate
AN EXTREME CASE STUDY
IDeAs Z-Squared Design Facility
Located in San Jose, CA
Retrofit of a 1960’s Building
6,560 sqft, 2-story
Urban Setting
Currently Operational
Z-Squared (net zero energy and net zero carbon emission
AN EXTREME CASE STUDY
All Electric
30kW Roof-Mounted PV Arrays
Heating and Cooling via GSHP
Heating System is Radiant Hot Water
Cooling System is Air
Significant Lighting Controls via Occupancy Sensors
Daylighting Monitors for Lighting of Building Core
Electrochromic Glass on Fenestrations to Reduce Solar Gains
Sunshades with Integral PV Cells
NZEB
ASHRAE NZEB Video
CONCLUSIONS
More to be done!
RESOURCES
DOE Websites
EERE: Building Technologies Program Home Page
NZEB Database
NZEB Projects
Building Energy Modeling Software
Financial Opportunities & Tax Incentives
ASHRAE
US Green Building Council
LEED
LEED Project Profiles