Making the Best Use of Energy Modeling in Designing High-Performance Green Buildings

1. Making the Best Use of Energy Modeling in Designing High-Performance Green Buildings by Andy Lau, PE, LEED AP July, 2007

2. Engineers Are Vital

3. USGBC’s Core Purpose To transform the way buildings are designed, built and operated, enabling an environmentally and socially responsible, healthy, and prosperous built environment that improves the quality of life in communities.

4. Reducing Energy Use • Reduce loads • Harmonize with climate • Optimize systems • Use renewable energy

5. The Heart of the Process – Integrated Design • Team-based • Stakeholders engaged throughout • Early goals and team alignment • Expertise engaged early & throughout • Building as organism • Reduce redundancies • Use analysis

6. Discovery Concept Design Schematic Design Design Development Construction Documents/ Delivery CoVO CoVO CoVO CoVO CoVO Front End Back End (CoVO)- Continuous Value Optimization Concept Design Schematic Design Design Development Construction Documents/ Delivery VE VE VE VE (VE)- Value Engineering Integrated Design Process Whole System Integrated Process (WSIP) Traditional Process

7. What is an Energy Model? A tool for … • estimating energy use and savings as a guide in design, • complying with standards, • optimizing economic and energy performance.

8. What an energy model is NOT: • A substitute for experience & collaboration • A tool for load calculations or HVAC system sizing • but it can account for the effect of building changes on HVAC sizes • A predictor of human behavior

9. Why do we need an Energy Model? • To inform decisions • Only way to account for synergistic interdependencies • Examples: Daylighting, Heat Recovery • LEED certification • Standardizes measurement of energy savings • Reduces “gamesmanship”

10. Synergistic Interdependencies Daylighting Heating & Cooling loads Window selection Electric Lighting Energy Use HVAC Size HVAC Energy Use NOTE: = $ Eliminate Perimeter Heating

11. Using it effectively • Climatic analysis • US EPA Target Finder analysis Pre-Design • Identify strategies • Set goals Design Charrette • Develop base case • Develop high-performance vision • Shape, massing • Windows & Building envelope • Daylighting • HVAC type • Individual EEM’s and combos Schematic Design

12. Using it effectively • Fine-tune details • Check progress, LEED points Design Development • “Value” engineering • Document for LEED Construction / Bidding • Calibrate model • Troubleshoot operation Commissioning

13. Start modeling ASAP When just 1% of a project’s up front costs are spent… up to 70% of its life-cycle costs may already be committed.

14. Pre-design – climatic analysis Hot and/or humid – avoid sun and air Mild – manage sun, use ventilation & air movement Cold & dry – allow sun and humidify

15. Pre-design – EPA Target Finder

16. Pre-design – EPA Target Finder

17. In Schematic Design • “Easy” via “wizard’s” • Define base case • Define proposed • Analyze EEM’s

18. Design Development Fine-tune the design • Optimization of specific components

20. Measurement & Verification • Proposed energy model is calibrated to actual post-occupancy operation conditions and weather data. • Verify that building systems and EEMs are operating as intended. • Problems can be identified and solutions analyzed. • Model can be improved next time.

21. Measurement & Verification DEP Cambria, Ebensburg, PA: LEED Silver

22. Electric Use Measurements

23. Occupancy Comparison 743 per-hr modeled vs. 706 per-hr reported (+5.1%)

24. Lighting Comparison 226 kwh modeled vs. 310 kwh measured (-27%)

25. Plug Loads Comparison 138 kwh modeled vs. 292 kwh measured (-53%)

26. Comparison of Actual Energy Use in 2002 with Calibrated PowerDOE Model HVAC Energy use is underpredicted by about 16%

27. Predicted Savings

28. Economics of Green Bldg’s • Holistic approach needed • Uses team knowledge • Emphasis on reducing redundancies • Comprehensive accounting BIG SAVINGS can cost less than Small Savings

29. Traditional Economic Approach (+) STOP Cost Effectiveness Limit Diminishing Returns (payback, ROI, capital budget) Added Cost Cumulative Savings (-) Rocky Mountain Institute

30. Tunneling through the Cost Barrier DETOUR (+) Cost Effectiveness Limit Diminishing Returns Cumulative Savings (-) Reduced Costs Rocky Mountain Institute

31. Neptune Township Community School NJ Elementary School/Community Center ● 145,600 GSF ● SSP Architectural Group

32. EEM’s • solar orientation • R27 wall w/ blown cellulose • R30 roof insulation • triple pane windows • LPD 0.92 W/sf • solar shading • light shelves • daylight dimming • ground source heat pumps • underfloor air • demand controlled ventilation • energy recovery units

33. Energy Modeling Results 40% load reduction

34. Energy Modeling Results • HVAC System: • Ground Source Heat Pumps • 40% load reduction = 10% cost reduction • 10% cost reduction = $400,000

35. Conclusions / Recommendations • Start early • Allow adequate time for the analysis • Communicate regularly and effectively • Recognize design integration issues • Danger of line item “Value” engineering • Use your head too!

36. Thank You