1. NET ZERO ENERGY BUILDINGS
Dr. Cy yavuzturk, ph.d, c.e.m.
College of engineering architecture and technology
Department of Mechanical engineering

2. 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

3. 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

4. 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

5. AN OVERVIEW
Energy Consumption by Source (DOE Energy Data Yearbook 2007)

6. AN OVERVIEW
Where Do We Consume Energy? (DOE Energy Data Yearbook 2007)

7. AN OVERVIEW
Building Energy Consumption Distribution (DOE Energy Data Yearbook 2007)

8. 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

9. 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.

10. 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.

11. 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 ), 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

12. NET ZERO ENERGY BUILDINGS
GETTING CLOSER!

13. NET ZERO ENERGY BUILDINGS
BUT THERE IS SIGNIFICANT WASTE!

14. 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

15. 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.

16. 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 new-constructions and retrofits:
REDUCE DEMAND FIRST, SUPPLY SECOND!

17. 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

18. 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

19. OTHER APPROACHES TO NET ZERO
Thermal Energy Storage
Controls

20. 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!

21. 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

22. THE FUNDAMENTALS
The Building Envelope:

23. THE FUNDAMENTALS
Internal Loads:

24. 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

25. 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)

26. 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

27. DESIGN FOR NZEB Waste heat recovery Evaporative cooling
Internal energy wheeling
Optimized controls
Occupant and operator training

28. 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

29. 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

30. 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

31. NZEB
ASHRAE NZEB Video

32. CONCLUSIONS
More to be done!

33. RESOURCES DOE Websites ASHRAE US Green Building Council
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