NET ZERO ENERGY BUILDINGS

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. 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

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 • 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