Energy Audit Lab (EX-705) - Unit 2 Short Notes

UNIT 2: ENERGY AUDIT LAB - SHORT NOTES

1.0 Introduction & Pre-Audit Planning

1.1 Purpose & Scope of a Laboratory Energy Audit

• Audit Types:

  | Audit Level | Depth & Focus | Typical Output | | :--- | :--- | :--- | | Preliminary | Walk-through, quick savings identification, low-cost measures | List of no-cost/low-cost opportunities | | Detailed | Comprehensive measurement, system-level analysis, firm savings estimates | Detailed report with calculated savings for ECMs | | Investment-Grade | Full engineering analysis, financial modeling, implementation plan | Business case for major capital investments |

• Audit Boundaries: Define physical (building, lab wing), temporal (operating hours), and system boundaries (HVAC, plug loads, process) clearly.

1.2 Audit Team Roles & Safety Protocols

• Team Roles:

  • Lead Auditor: Overall responsibility, planning, reporting.

  • Assistant Auditor: Data collection, instrumentation support.

  • Instrumentation Specialist: Setup, calibration, advanced measurements.

• Laboratory-Specific Safety:

  • Electrical Safety: Verify de-energized circuits before work, use appropriate PPE (gloves, face shield).

  • Lockout/Tagout (LOTO): Mandatory for any equipment or panel work.

  • Chemical/Biological Hazards: Review SDS, know lab-specific risks (fumes, vapors, pathogens).

  • PPE: Lab coat, safety glasses, gloves; additional PPE based on hazards.

1.3 Pre-Audit Data Collection & Review

• Documents to Review:

  • Building/lab floor plans, equipment schedules (make, model, rated power).

  • Utility bills (12-24 months) for electricity, gas, steam.

  • Operational schedules (24/7 research vs. scheduled classes).

• Key Focus: Identify energy-intensive processes (e.g., autoclaves, reactors, clean rooms) and baseline energy use patterns.

[!TIP] Common Pitfall: Assuming lab equipment is always "on." Verify actual runtime from schedules or preliminary measurements.

2.0 Instrumentation & Measurement Tools

2.1 Electrical Measurement Tools

2.2 Thermal & Environmental Measurement Tools

• Infrared (IR) Thermography:

  • Qualitative: Hot spot detection (overloaded panels, insulation gaps).

  • Quantitative: Requires correct emissivity setting and distance-to-spot ratio. Use for building envelope, steam traps, electrical equipment.

• Anemometers & Flow Meters:

  • Anemometers: Measure air velocity (fpm/m/s) in ducts, at fume hood faces.

  • Flow Meters: Measure fluid flow rate (GPM for water, SCFM for air) for chillers, compressors.

• Temperature & Humidity Data Loggers: Monitor lab ambient conditions, HVAC supply/return air, storage areas.

2.3 Light Measurement Tools

• Lux/Light Meter: Measures illuminance (lux or foot-candles). Take readings at workplane height (typically 3 ft above floor).

• Luminare Mapping: Plot measured lux levels across a grid to identify over/under-lit areas.

2.4 Calibration & Instrument Accuracy

• Calibration: Regular calibration against traceable standards ensures data validity. Always check calibration date.

• Accuracy vs. Precision: Accuracy = closeness to true value; Precision = repeatability. Note instrument error margin (±% of reading + digits).

[!TIP] Exam Focus: For IR thermography, remember that reflected ambient temperature can affect readings on shiny surfaces. Use tape or paint to increase emissivity.

3.0 Measurement Techniques & Data Collection Procedures

3.1 Electrical System Auditing

• Measure load profiles of major equipment (ovens, furnaces) over representative periods.

• Assess Power Factor (PF) and THD from non-linear loads (VFDs, computers). Low PF increases utility demand charges.

• Evaluate transformer loading and distribution losses (measure voltage drop across conductors).

3.2 HVAC System Auditing in Labs

• Air Changes per Hour (ACH):

$$ACH = \frac{\text{Airflow (CFM)} \times 60}{\text{Room Volume (ft}^3\text{)}}$$

. Measured via tracer gas decay or anemometer duct traverse.

• Fume Hood Evaluation:

  • Measure face velocity (target: 100 fpm at full sash opening).

  • Energy Impact: Exhaust rate ∝ (Face Velocity)³. A 2-inch sash height reduction can cut exhaust energy by ~30%.

  • DiagramSEARCH: fume hood face velocity measurement diagram

• Duct Leakage Testing: Pressurize duct system, measure leakage flow with balometer or flow hood.

• System Type Assessment: Identify inefficient Constant Air Volume (CAV) systems with reheat vs. efficient Variable Air Volume (VAV).

3.3 Compressed Air System Auditing

• Measure system pressure, compressor power (kW), and flow rate (SCFM).

• Leak Detection: Use ultrasonic detectors to locate leaks (audible hissing).

• Calculate pressure drop across filters/dryers; excessive drop indicates maintenance need.

3.4 Process & Specialized Equipment Auditing

• Measure energy consumption (kWh) and runtime for reactors, centrifuges, cryogenic systems.

• Quantify idle/standby losses by measuring power draw when equipment is "on" but not processing.

3.5 Lighting System Auditing

• Create inventory: luminare type, lamp wattage, ballast type, control type (switch, occupancy sensor).

• Measure current illuminance (lux) and compare to IESNA standards (e.g., 300-500 lux for general lab benches).

3.6 Building Envelope & Domestic Systems

• IR Scan: Detect insulation gaps, thermal bridges, air infiltration around windows, doors, lab walls.

  • DiagramSEARCH: infrared thermography building envelope

• Measure hot water flow rate and water heater input energy to calculate efficiency.

4.0 Data Analysis, Interpretation & Benchmarking

4.1 Organizing & Validating Field Data

• Create a master spreadsheet/database with all measurements, timestamps, locations.

• Cross-check data: Ensure power (kW) ≈ Voltage × Current × PF for three-phase systems. Flag outliers for re-measurement.

4.2 Energy Consumption Analysis

• Total Energy (kWh) = Sum of all measured/estimated loads over period.

• Peak Demand (kW): Highest 15/30-min interval demand from utility bill or logger.

• Load Factor:

$$Load\ Factor = \left( \frac{\text{Average Load (kW)}}{\text{Peak Load (kW)}} \right) \times 100\%$$

. Low LF (<50%) indicates underutilized capacity.

• Energy Use Breakdown: Pie chart of % contribution by HVAC, plug loads, lighting, process.

4.3 Efficiency Calculations

• System Efficiency: E.g., Chiller COP = $$\displaystyle \frac{\text{Cooling Output (BTU/hr)}}{\text{Electrical Input (W)} \times 3.412} $$.

• Specific Energy Consumption (SEC):

$$SEC = \frac{\text{Total Energy (kWh)}}{\text{Unit of Output (e.g., samples processed, liters produced)}}$$

. Key for process benchmarking.

4.4 Benchmarking & Savings Potential

• Benchmark Sources:

  • Lab design specs/ASHRAE 90.1.

  • Labs21 (now Better Buildings) benchmarks.

  • ENERGY STAR for labs (if available).

  • Peer institutions.

• Savings Assessment: Quantitative (kWh savings from ECM calc) vs. Qualitative (potential from observation, e.g., "24/7 equipment could be scheduled").

5.0 Identifying Energy Conservation Measures (ECMs) & Preliminary Savings Estimation

5.1 Common ECMs for Laboratory Settings

5.2 Simple Payback & Return on Investment (ROI) Calculation

• **Annual Cost Savings ($$\displaystyle )** = Annual Energy Savings (kWh/therms) × Utility Rate ( $$/kWh).

• Simple Payback Period:

$$\boxed{Simple\ Payback\ (years) = \frac{\text{Total Project Cost (\$)}}{\text{Annual Cost Savings (\$/year)}}}$$

• Limitations: Ignores time value of money, O&M savings, incentives. Use for initial screening only.

[!TIP] Exam Trap: Simple payback does not account for equipment lifetime. An ECM with 5-year payback may be excellent if equipment lasts 15 years.

6.0 Audit Reporting & Documentation (Lab Format)

6.1 Structure of an Energy Audit Report

1. Executive Summary: Key findings, top 3-5 ECMs, total savings, investment required.

2. Audit Scope, Methodology, Dates: Boundaries, tools used, team members.

3. Facility Description & Current Energy Profile: Lab types, operating hours, utility data summary.

4. Detailed Findings by System: Measured data tables, IR images, observations.

5. Recommended ECMs: Description, measured baseline, proposed action, estimated cost, calculated savings (kWh, $), simple payback.

6. Prioritized Implementation Plan: Quick wins (low cost, fast payback) vs. capital projects.

6.2 Presenting Technical Findings

• Charts/Graphs: Bar charts for energy breakdown, line graphs for load profiles.

• IR Thermograms: Annotate with temperature, location, suspected issue (e.g., "Missing insulation").

• Writing Style: Concise, factual, actionable. "Measurement on 10/26 showed fume hood face velocity of 150 fpm at 24-inch sash height, indicating 50% excess exhaust energy."

6.3 Laboratory-Specific Documentation

• Equipment Inventory Spreadsheet: Tag ID, location, make/model, rated power, measured power, runtime.

• Measurement Logs: Date, time, location, parameter measured, value, instrument, technician.

• Calibration Certificates: For all instruments used, valid during audit period.

• Safety & Access Logs: Document LOTO procedures, lab entry permissions, hazard acknowledgments.

[!TIP] Professional Practice: Always include a "Assumptions & Limitations" section in your report to clarify the basis of your savings calculations.