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

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Presentation on theme: "Making the Best Use of Energy Modeling in Designing High-Performance Green Buildings by Andy Lau, PE, LEED AP July, 2007."— Presentation transcript:

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 1. Reduce loads 2. Harmonize with climate 3. Optimize systems 4. Use renewable energy

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

6 Integrated Design Process Discovery Schematic DesignDesign Development Construction Documents/ Delivery Front EndBack End Concept Design (CoVO)- Continuous Value Optimization CoVO Schematic DesignDesign DevelopmentConstruction Documents/ Delivery Concept Design (VE)- Value Engineering VE 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, estimating energy use and savings as a guide in design, complying with standards, complying with standards, optimizing economic and energy performance. optimizing economic and energy performance.

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

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

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

11 Using it effectively Pre-Design Design Charrette Schematic Design Identify strategiesIdentify strategies Set goalsSet goals Climatic analysisClimatic analysis US EPA Target Finder analysisUS EPA Target Finder analysis Develop base caseDevelop base case Develop high-performance visionDevelop high-performance vision Shape, massingShape, massing Windows & Building envelopeWindows & Building envelope DaylightingDaylighting HVAC typeHVAC type Individual EEM’s and combosIndividual EEM’s and combos

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

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

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

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

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

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

22 Electric Use Measurements TABLE 1 Comparison of Measured Power Levels with PowerDOE Model (prior to calibration) Item Measured (kw) Modeled (kw) Difference (%) Pumps-ground loop Fans-HVAC Heat Recovery Ventilators Lights Equipment (plug)

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 ModelActualModel/Actual MonthEnergyDemandEnergy 1 DemandEnergyDemand (kwh)(kw)(kwh)(kw) Jan33, , Feb29, , Mar32, , Apr29, , May30, , Avg Comparison of Actual Energy Use in 2002 with Calibrated PowerDOE Model HVAC Energy use is underpredicted by about 16%

27 Predicted Savings Case Total (kwh) Bill ($) Bill ($/sq.ft.) Savings (%) ASHRAE Budget624,30264, Baseline Proposed Original253,81426, Proposed w/M&V Adj.343,41835,

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

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

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 EEMCostSavingsPayback Lower Lighting Power Density -$123,887$12,549NA Daylighting$90,350$16, Wood Triple Pane Windows $69,896$9, Extra Wall Insulation$46,302$9, R30 Roof Insulation$41,789$5, % load reduction

34 Energy Modeling Results EEMCostSavingsPayback EEM Combination$124,450$36, CostSavingsPayback Holistic Effect-$275,550$80,166?? HVAC System: Ground Source Heat Pumps 40% load reduction = 10% cost reduction 10% cost reduction = $400,000

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

36 Thank You


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