Energy Auditing for Schools Maryland Energy Administration Eric Oliver, EMO Energy Solutions, LLC May 10, 2007
Schools Consumption breakdown 19% 6% 9% Space Heating 46% Water Heating Lighting Cooling 20% Other U.S. DOE EERE
Energy Auditing Outline 1. Utility Consumption analysis 2. Kickoff meeting 3. Initial Walk through 4. Identification of opportunities 5. Follow up audits 6. Development of Energy Conservation Measures and Audit Report 7. Debriefing
Utility Consumption Analysis Benchmarking National Average approximately 70 kbtu/ft 2 Seasonal trending How high is summer consumption? Winter peak? Figure 2-1 Monthly kwh and Costs Figure 2-2 Monthly therms and Costs 700000 600000 500000 400000 300000 200000 100000 0 J F M A M J J A S O N D $45,000.00 $40,000.00 $35,000.00 $30,000.00 $25,000.00 $20,000.00 $15,000.00 $10,000.00 $5,000.00 $0.00 35000 30000 25000 20000 15000 10000 5000 0 J F M A M J J A S O N D $50,000.00 $45,000.00 $40,000.00 $35,000.00 $30,000.00 $25,000.00 $20,000.00 $15,000.00 $10,000.00 $5,000.00 $0.00 kwh Costs therms Costs
Kickoff Meeting Audit Timeline O&M Issues Wish List Access Review drawings Next Steps
Walk through audit Walk-through versus full-scale audit Comprehensive energy assessment Performed by a qualified energy service provider Monitor and measure Air temperatures Water flow rates and temperatures Electric demand of mechanical equipment Run times of lighting Assess O&M strategies, interview maintenance staff Develop detailed energy conservation measures Onsite renewable energy opportunities Detailed cost/savings estimates for improvements
Site Analysis Look for Quick Hits Oversized or outdated equipment not performing to needs Unnecessary/inefficient lighting Excess loads Ventilation in areas that aren t occupied Kitchen/office equipment on when not needed Heat loss/solar gain through windows/envelope Poor monitoring and/or controls Badly maintained HVAC
Site Analysis Monitoring and measurements Determine how equipment is operating Measure actual vs nameplate consumption Find areas of energy waste
Short term monitoring and datalogging Will gain a better understanding of how the building works May identify areas of energy waste
Identification of Opportunities Lighting Heating Cooling temperature and humidity control Eliminate energy waste Look for heat recovery renewable opportunitites
Develop Energy Conservation Measures (ECMs) Three-stage upgrade process Stage 1: Minimize Building Loads Stage 2: Improve System Effectiveness Stage 3: Optimize Resource Delivery
1. Minimize Building Loads This Includes: Improve building envelope (R-value, heat gain/loss) Reduce Internal Heat Gains Lighting power density (W/sqft) & usage Equipment power density (W/sqft) & usage Reduce Infiltration
Building Envelope Improve Wall & Roof Construction Insulation levels Surface absorption Thermal mass Improve Windows Double Glazing or storm windows Low-e coatings Spectrally selective coatings Utilize shading techniques Block solar penetration during the cooling season Allow solar gain during the heating season
Lighting Technology System Efficacy Incandescent T12 Fluorescent T8 Fluorescent T5 Fluorescent Metal Halide High Pressure Sodium Low Pressure Sodium LED 0 20 40 60 80 100 120 140 160 180 200 lumens/watt
Standard vs. Energy Efficient Lighting Size lumens life Annual costs Incandescent 100 W 1585 750 hr $21 Compact fluorescent 23 W 1580 10,000 hr $4.80 Fluorescent T12 vs T8 T12 12/8 diameter, 94 Watts per 2-lamp fixture T8 8/8 diameter, 58 Watts per 2-lamp fixture new 25W T8 46 Watts per 2-lamp fixture
Lighting Controls Occupancy Sensors - Detect motion or heat and initiate lighting Photocells - Monitor light levels to adjust lighting intensity when daylight is available
2. Improve System Effectiveness Air Distribution Cooling Heating Heat Recovery Direct Digital Controls Electrical Systems Service Hot Water Process Systems
Air Distribution Variable Air Volume Energy Savings Constant volume Supply 3750 cfm 1250 cfm 1250 cfm 1250 cfm VSD Variable volume Supply 2150 cfm SP 650 cfm 1050 cfm 450 cfm
Cooling Cooling Spot, window, air-cooled typically 1.0 1.5 kw/ton Chillers (30-tons +) Before 1990: 0.9 kw/ton 1990-1995: 0.7 0.9 kw/ton New HE: 0.4-0.6 kw/ton
Heating Standard existing : 60% efficient 40% wasted energy Standard new: 80% efficient Energy efficient: up to 95% efficiency Pulse condensing steam boilers Pre-heat combustion air Insulated tanks and pipes Efficient burners
Ground Source Heat Pumps Closed loop pipes buried underground to transfer heat Water loop heat pumps provide cooling or heating inside the building 40% to 60% less energy than chiller/boiler system
Building Controls Ways to Save Energy Unoccupied Settings Lighting schedules Chiller optimization Enthalpy Control Boiler optimization Smart controls Temperature (deg F) 79 78 77 76 75 74 73 72 71 70 69 Summer Temperature Setpoint 1 3 5 7 8 10 12 14 16 18 20 21 23 time (hour) Enthalpy - measure of combination of temperature and humidity of air
Heat Recovery Strategies Air/air heat exchangers Flat plate Enthalpy wheels Transfer heat & humidity between exhaust/supply Air/water heat exchangers Run-around coil loops No cross contamination Heat pipes
3. Optimize Resource Delivery Incorporate renewable energy technologies Incorporate energy storage techniques Investigate cogeneration
Renewable Opportunities Photovoltaics (PV) Facts: PV modules covering 0.3% of the land in the United States could supply all the electricity consumed in the U.S. How a solar cell works: The PV systems installed since 1988 in the developing world provide enough electricity to power 8 million homes there. http://www.eren.doe.gov/pv/pvmenu.cgi?site=pv&idx=1&body=aboutpv.html
Using the sun Passive vs Active Passive Uses the heat of the sun to offset fuel consumption Low cost Needs heating end use Can be 0-12 yr payback Variety of strategies Active Uses photovoltaic process to convert sunlight to electricity High cost Replaced purchased electricity 20 40 yr payback without assistance Limited technologies
Solar Power PV is still not cost effective without financial incentives installed costs in the range of $5 - $8/Watt typical payback 25 35 years California, New Jersey have good incentive programs cost effective for off-grid applications when compared to extending grid
Wind Power Where is there good wind?
Integrated Upgrades Description First Cost Annual Savings Payback Lighting Upgrade $65,000 $21,000 3.1 yr Install programmable thermostats $12,000 $8,500 1.4 yr Chiller Replacement $95,000 $27,000 3.5 yr Improve Boiler Combustion efficiency $1,500 $2,000 0.8 yr Insulate hot water pipes $3,000 $500 6.0 yr Install door thresholds $450 $140 3.2 yr Install Variable Speed Drives on fans $24,500 $9,500 2.6 yr Replace standard efficiency motors for chilled water pumping $2,300 $550 6.2 yr * Install 10 kw photovoltaic array $40,000 $1,600 25.0 yr * with tax credits Total $243,750 $70,790 3.4 yr