Operational Improvements

Operational improvements represent the lowest-cost approach to energy conservation, targeting system performance optimization without capital investment. These strategies focus on extracting maximum efficiency from existing equipment through better control, maintenance, and operating practices.

Scheduling Optimization

Operating equipment only when needed eliminates unnecessary energy consumption while maintaining comfort and functionality.

Occupancy-Based Scheduling

Time-based scheduling aligns system operation with building use patterns:

• Start/Stop Optimization: Calculate minimum lead time required to reach setpoint by occupancy time
• Optimal Start Algorithms: Use outdoor temperature, space temperature, and thermal mass characteristics
• Night Setback Recovery: Predict warmup/cooldown time based on ΔT and building thermal response
• Weekend/Holiday Scheduling: Reduce or eliminate operation during unoccupied periods
• Staged Equipment Start: Prevent demand peaks by sequencing equipment startup

Optimal start time calculation:

t_start = t_occupancy - (T_setpoint - T_current) / R_thermal

Where R_thermal represents building heating/cooling rate (°F/hr or °C/hr).

Zone-Level Scheduling

Independent scheduling for different building areas improves efficiency:

• Perimeter vs. Core: Different solar gain patterns require different schedules
• Multi-Tenant Coordination: Individual zone control for varied occupancy patterns
• After-Hours Overrides: Temporary occupancy accommodation with automatic reversion
• Cleaning Schedule Integration: Ventilation during custodial operations only
• Kitchen/Laboratory Exhaust: Match exhaust to actual use periods

Load Shedding Strategies

Strategic equipment cycling reduces peak demand without compromising comfort:

• Rotating Equipment Shutdown: Brief cycling of non-critical loads
• Pre-Cooling: Lower temperature before peak demand periods
• Thermal Mass Utilization: Leverage building thermal storage capacity
• Demand Response Integration: Automated response to utility signals
• Peak Demand Limiting: Real-time load monitoring with automated shedding

Setback and Setup Strategies

Temperature setback during unoccupied periods reduces heating and cooling loads significantly.

Night Setback Heating

Lower heating setpoint during unoccupied hours:

• Typical Setback: 55-60°F (13-16°C) for most commercial buildings
• Freeze Protection: Minimum 50°F (10°C) for piping protection
• Equipment Protection: Higher setpoints for sensitive equipment areas
• Humidity Considerations: Prevent condensation during setback periods
• Recovery Time: 1-3 hours typical for commercial construction

Energy savings equation:

Q_saved = UA × (T_normal - T_setback) × t_unoccupied

Cooling Setup

Raise cooling setpoint during unoccupied periods:

• Typical Setup: 80-85°F (27-29°C) for commercial spaces
• Humidity Limits: Maximum 60% RH to prevent moisture damage
• Computer Room Exceptions: Maintain tighter control for IT equipment
• Building Mass Impact: Heavy construction allows wider temperature swing
• Peak Load Consideration: Setup may increase peak cooling demand

Seasonal Adjustments

Optimize setpoints based on outdoor conditions:

• Shoulder Season: Wider acceptable temperature range (70-78°F vs. 72-76°F)
• Humidity-Based Limits: Tighter control during high humidity periods
• Occupant Adaptation: Gradual seasonal adjustment improves acceptance
• Clothing Factor: Consider seasonal dress code in setpoint selection
• Activity Level: Adjust for space function and metabolic heat generation

Economizer Operation

Free cooling using outdoor air when conditions permit reduces mechanical cooling energy substantially.

Economizer Control Strategies

Selection of appropriate control method affects energy savings:

Economizer Optimization Techniques

Maximize free cooling benefit through proper operation:

• Integrated Control: Coordinate economizer with mechanical cooling
• Minimum Damper Position: Ensure adequate ventilation air at all times
• Damper Sequencing: Modulate outdoor air before mechanical cooling
• Morning Purge: Pre-cool building with cool outdoor air before occupancy
• Night Cooling: Flush building heat during mild evenings
• High-Limit Shutoff: Prevent economizer operation during unfavorable conditions

Common Economizer Problems

Typical failures that eliminate energy savings:

• Stuck Dampers: Mechanical failure prevents modulation
• Failed Sensors: Incorrect readings cause improper control
• Control Logic Errors: Programming mistakes prevent economizer operation
• Minimum Position Too High: Excessive outdoor air during mechanical cooling
• Relief Damper Issues: Improper building pressure affects economizer capacity
• Mixed Air Temperature: Below dewpoint causes coil condensation and freezing

Maintenance Impact on Energy Performance

Proper maintenance preserves equipment efficiency and prevents energy waste.

Filter Maintenance

Clean filters reduce fan energy and maintain airflow:

• Pressure Drop Monitoring: Replace at 1.0-2.0 in. w.g. (250-500 Pa) depending on filter type
• Energy Impact: Each 0.5 in. w.g. increases fan power by approximately 10-15%
• Filter Selection: Balance filtration efficiency with pressure drop
• Prefilters: Extend life of final filters, reduce overall pressure drop
• Differential Pressure Sensors: Automate filter change notifications

Fan power relationship to pressure:

BHP = (CFM × ΔP) / (6356 × η_fan)

Coil Maintenance

Clean heat exchanger surfaces maintain heat transfer efficiency:

• Fouling Impact: Dirty coils reduce capacity by 10-30%
• Airside Cleaning: Annual cleaning prevents biological growth
• Waterside Cleaning: Remove scale and biological deposits
• Fin Straightening: Restore airflow through damaged fins
• Condensate Drain: Clear blockages to prevent water damage and IAQ issues

Belt and Drive Maintenance

Proper belt tension and alignment reduce energy loss:

• Belt Tension: Loose belts slip, wasting 5-10% of motor power
• Belt Condition: Worn belts reduce transmission efficiency
• Sheave Alignment: Misalignment increases belt wear and energy loss
• Direct Drive Benefits: Eliminate belt losses (3-5% efficiency gain)
• VFD Integration: Variable speed operation reduces mechanical stress

Bearing Lubrication

Proper lubrication reduces friction losses and prevents failure:

• Lubrication Schedule: Follow manufacturer recommendations
• Bearing Temperature: Monitor for excessive heat indicating problems
• Vibration Analysis: Detect bearing wear before failure
• Motor Efficiency: Poor bearings increase motor current draw
• Seal Condition: Prevent lubricant loss and contamination

Monitoring-Based Commissioning

Continuous monitoring identifies operational problems and optimization opportunities.

Key Performance Indicators

Track critical parameters to identify problems:

• Energy Use Intensity (EUI): kBTU/sf/yr or kWh/m²/yr
• Cooling Efficiency: kW/ton or COP
• Heating Efficiency: Combustion efficiency percentage
• Fan Efficiency: CFM/W or pressure rise per unit power
• Pump Efficiency: GPM/W or head per unit power
• Delta-T: Supply-return temperature difference indicates distribution efficiency

Fault Detection and Diagnostics

Automated analysis identifies operational faults:

• Simultaneous Heating and Cooling: Wasteful operation requiring correction
• Excessive Outdoor Air: Above minimum ventilation requirements
• Temperature Sensor Errors: Unrealistic or unchanging readings
• Economizer Faults: Damper position inconsistent with control logic
• Equipment Cycling: Short cycling indicates oversizing or control problems
• Schedule Adherence: Equipment operating outside scheduled hours

Trending and Baselining

Establish normal operation patterns to identify deviations:

• Load Normalization: Adjust for weather using degree-days or regression
• Seasonal Patterns: Compare current year to previous year same period
• Day-Type Comparison: Weekdays vs. weekends, occupied vs. unoccupied
• Benchmark Comparison: Compare to similar buildings or industry standards
• CUSUM Analysis: Cumulative sum charts reveal performance drift

Alarm Management

Effective notification ensures timely response to problems:

• Alarm Prioritization: Critical vs. informational classifications
• Setpoint Tolerance: Dead bands prevent nuisance alarms
• Alarm Delays: Time delays filter transient conditions
• Escalation Procedures: Automatic notification hierarchy
• Alarm Analysis: Review patterns to identify systemic issues

Reset Strategies

Adjusting supply temperatures based on demand reduces energy consumption.

Supply Air Temperature Reset

Raise supply air temperature when cooling loads decrease:

• Outdoor Air Reset: Increase SAT as OAT decreases
• Warmest Zone Reset: SAT based on zone requiring most cooling
• Return Air Temperature Reset: Maintain target return air temperature
• Typical Range: 55-65°F (13-18°C) depending on load
• Humidity Constraints: Minimum SAT to maintain dehumidification

Chilled Water Temperature Reset

Increase chilled water supply temperature reduces chiller energy:

• Outdoor Air Reset: 42-50°F (6-10°C) range based on OAT
• Load-Based Reset: Increase temperature during low load periods
• Valve Position Reset: Monitor valve positions, reset when all valves <90% open
• Chiller Efficiency Impact: Each 1°F increase saves approximately 1-2% compressor energy
• Dehumidification Limit: Maintain adequate coil temperature for latent removal

Hot Water Temperature Reset

Lower hot water temperature reduces heat loss and boiler cycling:

• Outdoor Air Reset: 120-180°F (49-82°C) range based on OAT
• Linear Reset: ΔT_hw proportional to ΔT_outdoor
• Design Day Operation: Maximum temperature at design outdoor temperature
• Domestic Hot Water Priority: Separate DHW from space heating for better control
• Condensing Boiler Optimization: Lower return temperature maximizes efficiency

Reset schedule example:

Variable Speed Drive Optimization

VFD operation reduces fan and pump energy through affinity law relationships.

Fan Speed Optimization

Reduce airflow during low load conditions:

• VAV System Reset: Lower static pressure setpoint based on damper positions
• Trim and Respond: Incrementally adjust setpoint to maintain minimum damper position
• Diversity Factor: Account for zones requiring simultaneous maximum airflow
• Minimum Speed: Maintain minimum 30-40% speed for stable operation
• Duct Pressure Distribution: Ensure adequate pressure at furthest zones

Energy savings relationship:

P₂/P₁ = (RPM₂/RPM₁)³

Reducing fan speed to 80% of design reduces power to 51% of design.

Pump Speed Optimization

Variable flow reduces pumping energy substantially:

• Differential Pressure Reset: Lower setpoint when control valves open
• Temperature-Based Control: Modulate flow to maintain ΔT
• Minimum Flow Requirements: Maintain chiller/boiler minimum flow
• Distribution Efficiency: Ensure adequate flow at furthest loads
• Decoupling Applications: Primary-secondary pumping with variable secondary

Demand Controlled Ventilation

Modulate outdoor air based on actual occupancy reduces conditioning load.

CO₂-Based Control

Carbon dioxide concentration indicates occupancy level:

• Setpoint Selection: 800-1000 ppm typical target above outdoor ambient
• Sensor Placement: Return air or representative zone location
• Minimum Ventilation: Maintain code-required minimum at all times
• Transient Response: Account for sensor lag and space mixing time
• Sensor Calibration: Verify accuracy annually, replace as needed

Ventilation rate equation:

CFM_vent = (G × 10⁶) / [CS(CO₂_space - CO₂_outdoor)]

Where G = CO₂ generation rate (CFM), CS = steady-state constant.

Occupancy Sensor Integration

Direct occupancy detection enables faster response:

• PIR Sensors: Passive infrared detects motion
• Dual Technology: Combines PIR with ultrasonic for better accuracy
• CO₂ Backup: Use both methods for redundancy
• Zone Aggregation: Combine multiple zones for smoother control
• Time Delays: Prevent rapid cycling on occupancy changes

Components

• Preventive Maintenance Efficiency
• Control System Optimization
• System Balancing Commissioning
• Economizer Optimization
• Supply Air Temperature Reset
• Chilled Water Temperature Reset
• Hot Water Temperature Reset
• Demand Controlled Ventilation
• Variable Speed Drive Optimization