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8.2 Energy Control Strategies: Temperature/Pressure Resets, Night Setback, and Deadbands
AEE Certified Energy Manager CEM
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1 Chapter 1: Energy and Sustainability Policies, Codes, and Standards
1.1 Federal and State Energy Policies, Decarbonization Targets, and ESG Reporting 1.2 Building Energy Codes: ASHRAE Standard 90.1, IECC, and Compliance Paths 1.3 Energy Management Systems: ISO 50001, ENERGY STAR Benchmarking, and Portfolio Manager
2 Chapter 2: Energy Rates, Tariffs, and Supply Options
2.1 Utility Rate Structures: Volumetric vs. Demand Charges, Time-of-Use (TOU), and Real-Time Pricing 2.2 Demand Charges, Ratchets, Peak Shaving, and Power Factor Penalties 2.3 Energy Procurement, Deregulated Markets, Supply Contracts, and Green Tariffs 2.4 Demand-Side Management, Load Curtailment, and Transportation Energy Efficiency
3 Chapter 3: Energy Audits and Instrumentation
3.1 Energy Audit Methodologies: ASHRAE Level I, II, and III Audit Scopes 3.2 Audit Instrumentation, Data Loggers, Metering Accuracy, and Safety (PPE) 3.3 Baseline Energy Data, Utility Bill Disaggregation, and ECM Identification 3.4 Energy Modeling, Simulation, Digital Tools, and Performance Indicators
4 Chapter 4: Energy Accounting and Economics
4.1 Energy & Power Units (kWh, kW, Therms, MMBtu, Joules) and Conversion Calculations 4.2 Financial Metrics: Simple Payback Period, Return on Investment (ROI), and LCCA 4.3 Time Value of Money: Net Present Value (NPV), Internal Rate of Return (IRR), and Escalation 4.4 Advanced Financial Evaluation: Annual Worth, SIR, Depreciation, and Interest Formulas
5 Chapter 5: Electrical Power Systems and Motors
5.1 Electrical Fundamentals: Single/Three-Phase Power, Apparent/Real/Reactive Power, and Power Factor 5.2 Electric Motors: Efficiency Classes, Loading Calculations, NEMA Premium, and Losses 5.3 Variable Frequency Drives (VFDs), Affinity Laws, and Electrical Harmonics
6 Chapter 6: Lighting Systems
6.1 Lighting Fundamentals: Photometric Quantities (Lumens, Lux, Foot-Candles, CRI, CCT) and Efficacy 6.2 Lighting Technologies & Retrofits: LED Systems, Fluorescent/HID Replacement, and LPD 6.3 Lighting Controls: Occupancy/Vacancy Sensors, Daylight Harvesting, Dimming, and Task Tuning
7 Chapter 7: HVAC Systems and Building Envelope
7.1 HVAC Fundamentals & Psychrometrics: Dry-Bulb, Wet-Bulb, Dew Point, Relative Humidity, and Enthalpy 7.2 Cooling and Heating Equipment: Chillers (COP, kW/ton, EER, SEER), Heat Pumps, and Boilers 7.3 Air and Water Distribution: AHUs, VAV vs. CAV, Pumping Systems, Fans, and Economizers 7.4 Building Envelope: Heat Transfer (U-factor, R-value, SHGC), Infiltration, and Thermal Insulation 7.5 Building Envelope Calculations: Degree-Days, Solar Heat Gain, and Passive Design 7.6 Refrigerants, Cooling Towers, and Specialized HVAC Technologies (Absorption, VRF, Chilled Beams)
8 Chapter 8: Building Automation, Controls, and Artificial Intelligence Systems
8.1 Building Automation Systems (BAS) Architecture, BACnet, Modbus, and DDC Loops 8.2 Energy Control Strategies: Temperature/Pressure Resets, Night Setback, and Deadbands 8.3 Fault Detection & Diagnostics (FDD), Energy Analytics, and AI Optimization 8.4 IoT, Cloud-Based BAS, Expert Systems, and Cyber-Security
9 Chapter 9: Energy Storage Systems
9.1 Battery Energy Storage Systems (BESS): Technologies, Capacity, Efficiency, and Safety 9.2 Thermal Energy Storage (TES): Chilled Water, Ice Storage, and Phase Change Materials 9.3 Storage Dispatch Strategies, Tariff Integration, Peak Shaving, and Microgrid Integration
10 Chapter 10: Boiler and Steam Systems
10.1 Boiler Fundamentals & Efficiency: Combustion Efficiency, Excess Air, and Stack Losses 10.2 Steam Distribution & Traps: Steam Trap Types, Failure Modes, Testing, and Insulation 10.3 Condensate Recovery, Boiler Blowdown Control, and Waste Heat Recovery
11 Chapter 11: Distributed Generation and Renewable Energy Systems
11.1 Solar Photovoltaic (PV) and Wind Energy Systems: Design, Inverters, and Capacity Factor 11.2 Combined Heat and Power (CHP) / Cogeneration: Thermal Efficiency and System Sizing 11.3 Grid Interconnection, Net Metering, Islanding, and Microgrid Resilience 11.4 Biomass, Geothermal, Hydropower, Solar Thermal, and Waste-to-Energy Systems
12 Chapter 12: Industrial Systems
12.1 Compressed Air Systems: Efficiency, Pressure Drop, Leak Management, and Receiver Storage 12.2 Industrial Process Heating, Cooling Towers, and Industrial Refrigeration 12.3 Production-Normalized Energy Metrics, Pumping System Optimization, and Process Integration
13 Chapter 13: Operations, Maintenance, and Commissioning
13.1 Preventive, Predictive, and Reliability-Centered Maintenance Strategies 13.2 Building Commissioning: Existing Building Commissioning (EBCx) & Retro-Commissioning (RCx) 13.3 Savings Persistence, Continuous Commissioning, Sensor Calibration, and Alarms 13.4 Quantifying O&M Losses: Compressed Air Leaks, Steam Traps, Boiler Scale, and Group Relamping 13.5 CMMS, Water Treatment, and Human Behavior in Energy Management
14 Chapter 14: Energy Savings Performance Contracting and Measurement & Verification
14.1 Energy Savings Performance Contracting (ESPC), ESCO Roles, and Financing Models 14.2 Measurement and Verification (M&V): IPMVP Options A, B, C, and D 14.3 Baselines, Weather Normalization, Non-Routine Adjustments, and M&V Reporting
8.2 Energy Control Strategies: Temperature/Pressure Resets, Night Setback, and Deadbands
Key Takeaways Explain This Topic AI
Reset schedules optimize efficiency by dynamically adjusting setpoints (e.g., chilled water temperature, supply air temperature) based on actual load or ambient conditions.
Increasing Chilled Water Supply Temperature (CHWST) significantly improves chiller efficiency, saving approximately 1% to 2% in compressor energy per degree Fahrenheit increased.
Night setback and setup strategies reduce energy consumption during unoccupied hours by expanding temperature limits and shutting down unnecessary ventilation.
Deadbands prevent simultaneous heating and cooling (energy waste) by establishing a neutral temperature zone where no mechanical conditioning occurs.
Duct static pressure reset strategies save significant fan energy by minimizing pressure to only what is required to satisfy the most demanding VAV box.
Last updated: July 2026
Energy Control Strategies: Temperature/Pressure Resets, Night Setback, and Deadbands
Implementing advanced control strategies through a Building Automation System (BAS) is one of the most cost-effective methods to achieve deep energy savings. Unlike capital-intensive equipment replacements, control optimizations leverage existing hardware by rewriting the software logic to ensure equipment only works as hard as absolutely necessary. The core philosophy of these strategies involves abandoning fixed setpoints in favor of dynamic setpoints that adapt to real-time building loads and ambient conditions.
Temperature and Pressure Reset Strategies
HVAC systems are traditionally designed to handle the absolute peak cooling or heating load (e.g., the hottest summer afternoon with full occupancy). Consequently, during the vast majority of operating hours (part-load conditions), the system is oversized. Reset strategies adjust operational setpoints during these part-load conditions to improve efficiency.
Chilled Water Supply Temperature (CHWST) Reset
Chillers are extremely energy-intensive. They typically provide chilled water at a fixed setpoint of 42°F to 44°F to handle peak dehumidification and cooling loads. However, when the outdoor temperature is moderate (e.g., 65°F), producing 44°F water is unnecessary.
A CHWST reset strategy dynamically raises the chilled water setpoint based on either the Outside Air Temperature (OAT) or the valve positions of the cooling coils in the building.
The Golden Rule of Chillers: Raising the chilled water supply temperature increases the chiller's efficiency. As a rule of thumb, chiller efficiency improves by 1% to 2% for every 1°F increase in the CHWST setpoint.
OAT-Based Reset Example:
When OAT > 85°F, CHWST Setpoint = 44°F (Peak load, maximum cooling capacity needed).
When OAT < 60°F, CHWST Setpoint = 54°F (Low load, warmer water is sufficient).
Between 60°F and 85°F OAT, the CHWST scales linearly between 54°F and 44°F.
Supply Air Temperature (SAT) Reset
Air Handling Units (AHUs) typically cool air to a fixed 55°F to satisfy building loads. Similar to the chiller reset, a SAT reset strategy raises the supply air temperature when cooling demand is low. This provides two massive benefits:
It reduces the cooling energy required at the AHU cooling coil.
It significantly reduces reheat energy . In many VAV systems, overcooled 55°F air must be reheated at the terminal box before entering a room to prevent overcooling the occupants. Raising the SAT to 60°F or 65°F during mild weather slashes this reheat penalty.
Duct Static Pressure Reset
Variable Air Volume (VAV) AHUs use Variable Frequency Drives (VFDs) to control fan speed, maintaining a fixed static pressure in the supply duct (e.g., 1.5 inches of water column, "w.c."). This fixed setpoint is chosen to ensure the most distant VAV box receives enough airflow during peak conditions.
A static pressure reset strategy polls the damper positions of all VAV boxes served by the AHU. If all VAV box dampers are less than 85% open, it means the system has excess pressure. The BAS slowly resets the static pressure setpoint downward (e.g., from 1.5" w.c. to 1.4" w.c., then 1.3" w.c.) until at least one VAV box damper opens to nearly 100%. By continually "starving" the system just enough to satisfy the most demanding zone, fan speed is minimized. Due to the Affinity Laws, even a small reduction in fan speed yields cubic reductions in fan power consumption.
Unoccupied Control Strategies
Buildings spend a massive percentage of their life unoccupied (nights, weekends, holidays). Optimizing controls during these periods is critical.
Night Setback and Night Setup
During unoccupied hours, there is no need to maintain strict occupant comfort standards.
Night Setback (Heating): The heating setpoint is lowered significantly (e.g., from 70°F to 60°F). The heating system remains off until the building temperature drops below 60°F.
Night Setup (Cooling): The cooling setpoint is raised significantly (e.g., from 74°F to 82°F). The cooling system remains off until the temperature exceeds 82°F.
Energy Savings Calculation Example: Consider a building operating 50 hours a week. It is unoccupied for 118 hours a week. Implementing a 10°F night setback reduces the temperature differential ( Δ T \Delta T Δ T ) between the inside and outside, drastically reducing heat loss through the building envelope. Savings from setback strategies typically range from 5% to 15% of total heating/cooling energy, depending on the severity of the climate, the mass of the building, and the length of the unoccupied period.
Optimum Start / Stop
Traditional scheduling starts the HVAC equipment at a fixed time (e.g., 5:00 AM) to ensure the building is comfortable by 8:00 AM. In mild weather, 3 hours of "warm-up" is wasteful.
Optimum Start is an intelligent algorithm that calculates exactly when to turn on the equipment based on the current indoor temperature, the outside temperature, and the historical thermal mass response of the building. On a mild day, it might start at 7:15 AM; on a freezing day, it might start at 4:30 AM. Optimum Stop performs the reverse, shutting down mechanical cooling/heating before the occupants leave, allowing the building to "coast" on its thermal inertia for the final 30-60 minutes of the day.
Zone Temperature Control: The Deadband
A deadband is a temperature range in which neither heating nor mechanical cooling is activated. It is the neutral zone separating the heating setpoint and the cooling setpoint.
Without a deadband (or with a very narrow one), a system might heat a room to 72°F, overshoot slightly to 73°F, immediately trigger the cooling system to bring it back to 72°F, and oscillate endlessly. This is known as simultaneous heating and cooling , and it is one of the worst forms of energy waste.
Typical Occupied Setpoints: Heating = 70°F, Cooling = 74°F.
Deadband: 4°F (from 70°F to 74°F).
When the space temperature is 72°F (inside the deadband), the VAV box damper modulates to its minimum position to provide ventilation air only, and no mechanical heating or cooling is applied. Widening the deadband (e.g., to 69°F heating and 75°F cooling) significantly reduces energy consumption by allowing the building temperature to float freely over a wider range before expending energy.