What is this measure?

The retro-commissioning package includes operation and maintenance measures. Estimates for these measures come from the Department of Energy's Advanced Energy Retrofit Guide. These include:

Reduce envelope leakage

Air leakage through the building envelope most often occurs where building envelope elements are connected together. Leakage is typically a result of either improper design or construction, lack of maintenance, or normal degradation over the life of a building. Envelope leakage is most pronounced when the HVAC system is off, i.e., when the building is not mechanically pressurized. Significant night-time air leakage causes the HVAC systems to operate harder upon morning start-up, to bring the building back to setpoint temperature.

Energy savings can be achieved by identifying significant air leaks in the building envelope and sealing them. Specific methods of sealing will vary depending on the component(s) being sealed. In general, large gaps should be sealed with a structural material before applying caulk.

For office buildings, common areas of air leakage include curtain wall structures, soffits, roof-to-wall joints, expansion joints, parapet flashing, and roof penetrations. Infrared cameras can help identify air leaks in buildings.

Air leakage can affect occupant comfort, HVAC system performance, window and door performance, and building energy usage.

Revise air filtration system

Many large built-up air handling systems include both pre-filters and final filters for cleaning the air before it is supplied to the zones. The pre-filters are installed to extend the life of the final filters, yet typically they do not achieve this since it’s easy for dust to pass through and around the pre-filters. In addition, the pre-filters impose significant additional pressure drop, resulting in higher fan energy use and maintenance costs. Extended surface area filters are now available that can replace both the pre-filter and final filter. These extended surface filters have a long life (high dust holding capacity) and low pressure drop characteristics. Both maintenance (labor) and energy savings can be achieved by using these types of filters.

Calibrate air-sensors

HVAC systems rely on input from sensors to determine how to operate. However, these sensors can drift out of calibration over time. Sensors found in typical HVAC systems can include, but aren’t limited to, temperature, pressure, and flow sensors. If these sensors are not calibrated - i.e., if the value being reported by the sensor does not match the actual condition – this could negatively impact equipment performance and occupant comfort, and could result in energy waste due to simultaneous heating and cooling. Calibrated sensors are necessary for automatic control sequences to operate properly, and for accurate diagnoses of system performance.

This measure requires developing and implementing a sensor calibration plan. In general, sensor calibration consists of comparing reported sensor readings (e.g., at the building automation system) with readings from a calibrated device, and taking corrective action where there’s a significant difference between the two readings. Corrective action might include simple offsets or multipoint calibrations to align the readings. If the sensor is significantly out of calibration, replacement may be necessary. For example, if the supply air temperature setpoint is reset based on outside air temperature, it’s important to ensure that the outside air temperature sensor is calibrated and located in a representative location.

Re-enable the supply air temperature setpoint reset

For multi-zone air systems, whether CAV or VAV, automatically changing the supply air temperature setpoint to better match the needs of the zones can result in lower reheat energy use due to reduced amount of zone reheat (simultaneous heating and cooling). The supply air temperature setpoint is typically reset based on either outside air temperature or an indication of zone demand - e.g., average difference between zone temperature and zone temperature setpoint.

Care should be taken when implementing this measure to verify that internal zones receive enough cooling at higher supply air temperatures. While significant reheat energy can be saved by implementing this measure, there is usually a slight increase in fan energy usage due to internal zones requesting more airflow at the higher supply air temperatures to maintain space conditions. This fan energy penalty should be weighed against the reheat energy savings.

Reduce HVAC runtime, close outdoor air dampers during unoccupied periods

The maximum energy savings related to an HVAC system can be achieved by shutting the system off when not in use to minimize run time. This measure reduces the scheduled operating hours of the HVAC system, including fans, pumps, chillers and boilers, to more closely match the occupancy of the building.

In addition, many HVAC fan systems operate with the outside air damper open whenever the fans are operating, even during morning warm-up and cool-down periods, prior to the occupied period. Since ventilation is only required during occupied hours, the outside air dampers can be closed during non-economizer operation in unoccupied hours. This feature eliminates the energy associated with cooling and heating outside air when ventilation is not required.

Reduce economizer damper leakage

An airside economizer cycle utilizes outside air for cooling a facility when the outside conditions are cooler than inside conditions. Economizer cycles reduce the amount of mechanical cooling energy necessary for cooling a facility. During integrated airside economizer cycle operation, when the outside temperature is cooler than the indoor temperature yet warmer than the supply air temperature necessary for cooling the space, the outside air dampers are fully open and the return air dampers are fully closed.

If the return dampers are leaky, meaning if they don’t have blade and jamb seals and/or they are not adjusted to close fully when commanded to do so, the effectiveness of the economizer cycle is reduced and more mechanical cooling is required than would be necessary if the dampers leaked less.

Some HVAC systems include a morning warm-up/cool-down cycle. During this cycle, the space is cooled or heated to address the heat gained or lost during the night (unoccupied period). Typically this cycle occurs prior to the start of the occupied period, and the minimum outside air dampers remain closed during this period. If these dampers are leaky, more outside air would be drawn in than is necessary, adding an unnecessary load on the HVAC system.

Minimizing the air leakage through closed outside and return air dampers can reduce HVAC system energy use during integrated economizer operation and morning warm-up/cool-down cycles.

Calibrate water sensors

HVAC systems rely on input from sensors to determine how to operate. However, these sensors often drift out of calibration over time. Typical waterside sensors can include temperature, pressure, and flow sensors, to name a few. If these sensors are not calibrated – i.e., if the value being reported by the sensor does not match the actual condition – this could negatively impact equipment performance and occupant comfort, and could result in energy waste due to simultaneous heating and cooling.

This measure consists of developing and implementing a sensor calibration plan. In general, sensor calibration consists of comparing reported sensor readings (e.g., at the building automation system) with readings from a calibrated device, and taking corrective action where there’s a significant difference between the two readings. For example, if chillers are staged based on measured chilled water flow, then it’s especially important to regularly calibrate the chilled water flow sensor to maintain performance, equipment reliability, and energy efficient operations.

Shut down the cooling plant when there is no cooling load

Facilities often run their cooling plants continuously during occupied periods of the cooling season. This includes the chiller, cooling tower, and related pumps. However, there may be periods during the cooling season when the plant does not need to run, especially when airside economizer cooling is used at the air handlers. If there is a space that requires continuous cooling, even after hours, it may be more efficient to install a small cooling system to serve this space, and turn off the larger plant.

Automatic controls can be added to turn off the entire cooling plant when cooling is not needed in the facility during occupied hours. Two common automatic methods include:

• Outside air temperature or enthalpy-based lockout. These controls would turn off the cooling plant when the temperature or enthalpy drops below a certain value.
• Enable plant based on the cooling demand. These controls would turn off the cooling plant when there is no cooling demand (e.g., all air handler cooling coil valves are closed). Adequate time lags and proper trigger points need to be programmed with this strategy to prevent the plant from cycling on and off excessively.

 

Before this measure is implemented, the retro-commissioning team should ensure that the cooling plant is not operating after hours. Turning the cooling plant off during unoccupied hours is typically easier to implement than cooling plant shutdown during occupied hours, due to greater building operator buy-in.

For facilities with multiple chillers, the chiller staging strategy can have a large impact on the energy consumption of the plant. It’s often beneficial to shut off chillers at low load, to reduce pumping energy consumption and increase chiller efficiency. Each facility is different, and will have its own optimal chiller staging strategy. BAS software overlays are available that will continually optimize the performance of a chilled water plant.

In addition to energy savings, this measure should result in increased equipment life due to less run hours for the cooling plant.

This measure may not apply to smaller buildings, which typically do not have a cooling plant.

What is this measure?

Estimates for these measures come from the Department of Energy's Advanced Energy Retrofit Guide. The standard retrofit package includes the following measures:

Install occupancy sensors for lighting

Since lighting is typically required only when people are present, fixed lighting operating schedules may use more energy than necessary in zones with intermittent occupancy. Installing occupancy sensors in applicable zones will automatically match the lighting operation with occupancy. This helps minimize lighting run time and saves energy when compared with fixed operating schedules

Special Considerations

• Occupancy sensors work best in locations where there will be a minimal amount of false triggering, and where the lighting fixtures can respond (turn on) quickly
• The most common occupancy sensor types are ultrasonic (motion detection) and passive infrared (heat detection). In general, ultrasonic sensors are more suited for larger areas, and passive infrared sensors are more suited for smaller areas, within a 15-foot range.
• Occupancy sensors are most cost-effective when they serve spaces that are intermittently occupied, such as open offices, closed offices, conference rooms, restrooms, stairwells, and break rooms.

 

Install daylight harvesting sensors

Daylight harvesting sensors require the installation of photocells to sense the space lighting level and control the overhead lighting in the perimeter zones to maintain a constant light level in the space. This measure also includes replacing the overhead lighting with dimmable ballasts, since dimmable ballasts are necessary to realize energy savings.

Special Considerations

• The lighting next to the exterior windows needs to be on a separate circuit from the other lighting, so that these lights can be controlled separate from the interior zone lights.
• The design of a daylight harvesting system should account for sensor location, sensor orientation, and number of sensors. During installation, the light sensitivity settings need to be adjusted so that the desired lighting level is maintained in the space. Also, the system should be periodically tested for proper functionality.

 

Retrofit exterior lighting fixtures to reduce lighting power density (LPD) and exterior lighting control

This measure involves replacing a facility’s parking area lighting fixtures with more efficient fixtures that will deliver the same illumination at reduced power draw, and reducing the lighting level during unoccupied periods. Parking areas are traditionally lit with high-intensity discharge (HID) lighting fixtures, typically metal halide or high pressure sodium lights. Replacing these fixtures with newer, more efficient technologies such as light-emitting diodes (LED) will yield energy savings.

For office buildings, exterior lighting typically consists of parking area, walkway, and building façade lighting. This lighting is typically turned on at sunset and turned off at sunrise, based on photosensor or astronomical timeclock control. Energy savings can be realized by lowering the exterior lighting level below full load power during times when nobody is present.

Special Considerations

• Overall lighting system efficiency, fixture life, light output depreciation, maintenance, environmental impact, and controllability should all be considered when replacing lighting fixtures.

 

Widen zone temperature deadband (pneumatic zone controls)

Deadband is the difference between the zone heating and cooling temperature setpoints. Widening the zone temperature deadband of the HVAC distribution system (e.g., piping, ductwork, terminal units) will result in measurable energy savings at the HVAC central equipment (e.g., boilers, chillers, air handlers). It’s common for HVAC systems to operate with little to no deadband, meaning that there is one temperature setpoint during winter and summer seasons.

Specific zone control energy conservation modifications will vary by HVAC system type and the specific needs and capabilities of each facility. It’s important to integrate the controls of both the central equipment and the distribution system for maximum energy efficiency and occupant comfort.

Special Considerations

• Widening the deadband with pneumatic controls will likely involve replacing the thermostats with ‘zero energy band’-type thermostats that have an adjustable deadband and manually setting the deadband at each thermostat. If a system already has direct digital controls at the distribution level, widening the deadband can be as simple as a global change to the heating and cooling setpoints made from the main operator workstation.

 

Lower variable air volume (VAV) box minimum flow setpoints (pneumatic zone controls)

For HVAC systems with variable air volume (VAV) systems, reducing the zone supply airflow during periods of low cooling and heating load will result in measurable energy savings at the central equipment (e.g., boilers, chillers, air handlers). Specific zone control energy conservation modifications will vary by HVAC system type and the specific needs and capabilities of each facility. It’s important to integrate the controls of both the central equipment and the distribution system for maximum energy efficiency and occupant comfort.

Special Considerations

• During periods of no heating and cooling, VAV boxes must still deliver air to the zones in order to provide ventilation air for the occupants. For commercial office buildings, this airflow rate, the “minimum airflow”, is almost always a fraction of the peak airflow rate required during peak cooling periods. Oftentimes these minimum airflow rates are set higher than needed – a common strategy is to set the minimum at 50% of the maximum, even though less than 50% of maximum airflow is required for ventilation. Energy savings can be realized by lowering the minimum airflow rate to a level that still provides adequate ventilation air for the occupants, but will result in reduced fan and reheat energy used by the system.
• The minimum airflow rates should be calculated for each zone, since each zone will have different requirements.
• Lowering the VAV box minimum flow setpoints mostly involves TAB (testing, adjusting and balancing) work. If a system already has direct digital control at the distribution level, the minimum flow setpoints can be lowered at the main operator workstation.

 

What is this measure?

Since lighting is typically required only when people are present, fixed lighting operating schedules may use more energy than necessary in zones with intermittent occupancy. Installing occupancy sensors in applicable zones will automatically match the lighting operation with occupancy. This helps minimize lighting run time and saves energy when compared with fixed operating schedules

Special Considerations

• Occupancy sensors work best in locations where there will be a minimal amount of false triggering, and where the lighting fixtures can respond (turn on) quickly
• The most common occupancy sensor types are ultrasonic (motion detection) and passive infrared (heat detection). In general, ultrasonic sensors are more suited for larger areas, and passive infrared sensors are more suited for smaller areas, within a 15-foot range.
• Occupancy sensors are most cost-effective when they serve spaces that are intermittently occupied, such as open offices, closed offices, conference rooms, restrooms, stairwells, and break rooms.

Estimates for this measure come from the Department of Energy's Advanced Energy Retrofit Guide.

What is this measure?

Daylight harvesting sensors require the installation of photocells to sense the space lighting level and control the overhead lighting in the perimeter zones to maintain a constant light level in the space. This measure also includes replacing the overhead lighting with dimmable ballasts, since dimmable ballasts are necessary to realize energy savings.

Special Considerations

• The lighting next to the exterior windows needs to be on a separate circuit from the other lighting, so that these lights can be controlled separate from the interior zone lights.
• The design of a daylight harvesting system should account for sensor location, sensor orientation, and number of sensors. During installation, the light sensitivity settings need to be adjusted so that the desired lighting level is maintained in the space. Also, the system should be periodically tested for proper functionality.

Estimates for this measure come from the Department of Energy's Advanced Energy Retrofit Guide.

What is this measure?

Deadband is the difference between the zone heating and cooling temperature setpoints. Widening the zone temperature deadband of the HVAC distribution system (e.g., piping, ductwork, terminal units) will result in measurable energy savings at the HVAC central equipment (e.g., boilers, chillers, air handlers). It’s common for HVAC systems to operate with little to no deadband, meaning that there is one temperature setpoint during winter and summer seasons.

Specific zone control energy conservation modifications will vary by HVAC system type and the specific needs and capabilities of each facility. It’s important to integrate the controls of both the central equipment and the distribution system for maximum energy efficiency and occupant comfort.

Special Considerations

• Widening the deadband with pneumatic controls will likely involve replacing the thermostats with ‘zero energy band’-type thermostats that have an adjustable deadband and manually setting the deadband at each thermostat. If a system already has direct digital controls at the distribution level, widening the deadband can be as simple as a global change to the heating and cooling setpoints made from the main operator workstation.

Estimates for this measure come from the Department of Energy's Advanced Energy Retrofit Guide.

What is this measure?

For HVAC systems with variable air volume (VAV) systems, reducing the zone supply airflow during periods of low cooling and heating load will result in measurable energy savings at the central equipment (e.g., boilers, chillers, air handlers). Specific zone control energy conservation modifications will vary by HVAC system type and the specific needs and capabilities of each facility. It’s important to integrate the controls of both the central equipment and the distribution system for maximum energy efficiency and occupant comfort.

Special Considerations

• During periods of no heating and cooling, VAV boxes must still deliver air to the zones in order to provide ventilation air for the occupants. For commercial office buildings, this airflow rate, the “minimum airflow”, is almost always a fraction of the peak airflow rate required during peak cooling periods. Oftentimes these minimum airflow rates are set higher than needed – a common strategy is to set the minimum at 50% of the maximum, even though less than 50% of maximum airflow is required for ventilation. Energy savings can be realized by lowering the minimum airflow rate to a level that still provides adequate ventilation air for the occupants, but will result in reduced fan and reheat energy used by the system.
• The minimum airflow rates should be calculated for each zone, since each zone will have different requirements.
• Lowering the VAV box minimum flow setpoints mostly involves TAB (testing, adjusting and balancing) work. If a system already has direct digital control at the distribution level, the minimum flow setpoints can be lowered at the main operator workstation.

Estimates for this measure come from the Department of Energy's Advanced Energy Retrofit Guide.

What is this measure?

Deadband is the difference between the zone heating and cooling temperature setpoints. Widening the zone temperature deadband of the HVAC distribution system (e.g., piping, ductwork, terminal units) will result in measurable energy savings at the HVAC central equipment (e.g., boilers, chillers, air handlers). Putting the HVAC system in standby mode for zones that are unoccupied will also result in energy savings. Specific zone control energy conservation modifications will vary by HVAC system type and the specific needs and capabilities of each facility. In general, for centralized HVAC systems, it’s important to integrate the controls of both the central equipment and the distribution system for maximum energy efficiency and occupant comfort.

Special Considerations

• For hybrid systems (digital control at the plant, pneumatic at the zones), extending DDC control to the distribution level and providing enough capacity in the DDC system to allow for communication between the central equipment and the distribution system paves the way for implementing advanced control sequences that will help minimize energy consumption of the HVAC system, especially during non-peak heating and cooling periods. Extending digital control to the distribution level also allows operators to monitor performance of these systems and troubleshoot issues faster.

Estimates for this measure come from the Department of Energy's Advanced Energy Retrofit Guide.

What is this measure?

For HVAC systems with variable air volume (VAV) systems, reducing the zone supply airflow during periods of low cooling and heating load will result in measurable energy savings at the central equipment (e.g., boilers, chillers, air handlers). In addition, reducing or resetting the duct static pressure setpoint will also result in energy savings. Specific zone control energy conservation modifications will vary by HVAC system type and the specific needs and capabilities of each facility. In general, for centralized HVAC systems, it’s important to integrate the controls of both the central equipment and the distribution system for maximum energy efficiency and occupant comfort.

Special Considerations

• Lowering the VAV box minimum flow setpoints mostly involves TAB (testing, adjusting and balancing) work. If a system already has DDC control at the distribution level, the minimum flow setpoints can be lowered at the main operator workstation.
• Prior to lowering the duct static pressure setpoint or implementing an automatic reset strategy, it’s a good idea to verify the integrity of the duct system. Check to see if there is excessive leakage in the system. If a certain area has recurrent comfort complaints, check to see if there are obstructions in the ductwork (e.g., duct liner that has peeled away from the duct, closed fire dampers). Also check to see if there are an excessive number of duct elbows in the ductwork serving that area.
• VAV box damper position is a good input variable to use for resetting the duct static pressure setpoint: raise the setpoint if a certain number of dampers are 100% open, lower the setpoint if most of the dampers are less than 100% open.

Estimates for this measure come from the Department of Energy's Advanced Energy Retrofit Guide.

What is this measure?

This measure involves replacing a facility’s supply fan motors and VFDs with premium efficiency motors and VFDs with current technology. Standard motor efficiencies have steadily increased over the last few decades due to improvements in motor design and manufacturing, and VFD efficiencies have increased greatly over the past 10 years. Minimum motor efficiencies prescribed in building energy codes and federal regulations are frequently increased to keep pace with these improved efficiencies.

Special Considerations

• Most facilities do not consider upgrading motors or VFDs with higher efficiency models until the existing motors or VFDs need to be replaced due to failure or system replacement/reconfiguration. However, it may be worth replacing large, old VFD/motor combinations that operate frequently with more efficient models even before failure.

Estimates for this measure come from the Department of Energy's Advanced Energy Retrofit Guide.

What is this measure?

Lighting is often an area targeted for improvement in existing office buildings. Lighting upgrades can come in many forms, including light-emitting diodes (LEDs), high-efficiency fluorescents, or downsizing from T-12 fluorescent bulbs to T-8 or T-5 bulbs. Lighting accounts for 30-40% of commercial building energy consumption, and these technologies can reduce lighting energy usage from 35% (T-8 high efficiency fluorescent) to 75% (LED).

Special Considerations

• When replacing fluorescent tubes with higher-efficiency, longer-life LEDs, consider replacing the entire fixture to avoid incompatibilities between the bulb and the ballast which could degrade performance, shorten bulb life, or create a safety hazard.  Alternatively, use an LED tube with an integrated driver.
• Consider bundling this upgrade with occupancy and/or daylight sensors for additional savings.

Estimates for this measure come from the Department of Energy’s Energy Efficiency in Separate Tenant Spaces Feasibility Study.

What is this measure?

Energy Star independently certifies appliances and their operation costs. Products include refrigerators and dishwashers for kitchens, vending machines and coffee makers for break rooms, and a large portion of computer and office equipment. Though a premium of $50-200 can apply for an Energy Star certified product, the energy usage is usually 10-40% lower than non-certified products, providing a typical payback within 1 to 3 years.

Special Considerations

• Energy Star also administers the Portfolio Manager program, a free resource that tracks energy and water usage of your building, which can lead to an Energy Star certification for your entire building!

Estimates for this measure come from the Department of Energy’s Energy Efficiency in Separate Tenant Spaces Feasibility Study.

What is this measure?

Energy management and information systems are software tools that interface with a building to manage and control energy use. In addition to benchmarking and utility tracking (like Energy Star’s Portfolio Manager), building automation systems (BAS) are a common form of EMIS. A BAS is a computer based tool that allows the facility manager to control everything from HVAC to lighting to security systems. The Department of Energy has extensive information on EMISs through the Better Buildings Program.

Special Considerations

• There are many different types of systems that qualify as energy management systems. Learn more about the specifics and how they can save you money with this report from the Lawrence Berkeley National Laboratory:
• Energy Information Systems (EIS): Technology Costs, Benefit, and Best Practice Uses

Estimates for this measure come from the Department of Energy’s Energy Efficiency in Separate Tenant Spaces Feasibility Study.

What is this measure?

As buildings age, their envelopes can lose efficiency and require upkeep to avoid excessive heating and cooling costs. Recaulking windows is a cheap and cost-effective way to seal up the building and prevent heating/cooling loss, saving anywhere from 3-12% in HVAC costs. Solutions can in also include adding automatic shades or blinds and introducing a vestibule at the entrances of the building to prevent energy losses dependent on the outside temperature. Thermal imaging (see picture) can be used to identify areas of your building particularly prone to energy loss and due for upgrade.

Special Considerations

• The cost of improving your building’s exterior will vary based on the technology chosen. Consult the Department of Energy’s Energy Efficiency in Separate Tenant Spaces Feasibility Study for details on ways to improve your building envelope’s performance.

What is this measure?

What Is This Measure?

More than 25% of total energy consumed in US office buildings is used to power plug-in devices, many of which continue to draw power even when turned off. Advanced power strips (APS) that employ pre-programmed timers to de-energize such devices significantly reduce power usage:  26% at workstations and 50% in printer rooms and kitchens.

Special Considerations

Load-sensing and combination controls provided limited energy savings and relatively high simple payback. One reason for this is that when applied to kitchens or printer rooms, load-sensing control aggregates power-state data from APSs in surrounding workstations. Because all workstation APSs are monitored in search of a “master” device whose threshold would de-energize auxiliary devices, “slaves” are de-energized only when all workstations are de-energized, which seldom occurs if occupants are present.

See GSA’s Green Proving Ground for more details on the field demonstration findings.

What is this measure?

What Is This Measure?

The wireless pneumatic thermostat (WPT) is a new technology that can be retrofitted to an existing pneumatic control system. WPTs give conventional pneumatic controls the energy-conserving functionality of more contemporary control systems, such as direct digital controls (DDC), but at a fraction of the cost. Payback was as low as two years, using only the most basic occupied/unoccupied control strategy. If other strategies were implemented, the potential for energy savings and financial viability would be greater.

WPT represents an economically viable technology that can reduce HVAC energy consumption, resulting in lower energy costs across a wide variety of office types and climate zones. It should be considered for any facility that currently uses conventional pneumatic controls with their HVAC system.

Special Considerations

It is advisable to perform pre-installation tests to determine how well wireless signals can be transmitted within a building where a WPT retrofit is being considered.

Planning for a WPT occupied/unoccupied control strategy should take into account the possibility of reduced energy savings in areas where high thermal mass stabilizes temperature over longer periods of time. During the WPT assessment, some interior areas within the concrete-and-steel Wilson Center did not demonstrate temperature changes normally associated with an occupied/unoccupied schedule, though other indicators suggested that such a schedule was in effect. After exploration of the issue, it was determined that the high thermal mass of the interior spaces was slowing temperature changes that were occurring more rapidly in the building’s exterior spaces.

See GSA’s Green Proving Ground for more details on the field demonstration findings.

What is this measure?

What Is This Measure?

Cogged V-belts and synchronous-drive fan belts are a low-investment way to reduce the inefficiencies in ventilation fans caused by belt slippage and bending resistance. GSA, Rocky Mountain Region, put both belts to the test on two different fans in Denver, Colorado, and found significant energy savings with a simple payback of less than four years.

Special Considerations

• Synchronous drive belts and cogged V-belts provide a relatively simple, low-cost way of achieving energy savings, but they must be installed correctly and applied in appropriate situations.
• For VFD fans, the synchronous drive belts performed well and showed savings at all ranges of fan operation.
• For CV fans, cogged V-belts are the best solution. Synchronous drive belts pose risks when combined with the CV fan’s high-torque starts and increased operational speed.

See GSA’s Green Proving Ground for more details on the field demonstration findings.

What is this measure?

What Is This Measure?

Small circulator pumps (< 2.5 horsepower) propel fluid through closed-loop heating and cooling systems to regulate air or water temperature. Researchers evaluated new high-performance variable-speed circulator pumps with automated control that adjust pump speed to meet changing demand. They tested the technology in two common applications at the Denver Federal Center, a domestic hot water (DHW) recirculation system and an air handler unit (AHU). They found that the pumps reduced energy use 26% to 96%, with payback of less than 6 years. The new variable speed pumps should be considered as end-of-life replacements for all constant speed circulator pumps.

Special Considerations

Because differential pressure and accurate flow readings are not readily available for smaller constant-volume circulator pumps, use one of the following methods to right-size the pumps:

• Determine pipe sizes and lengths and then calculate actual head loss from the pipes to estimate the flow (GPM) and head required for the pump.
• Observe supply and return temperature differentials to make an educated guess about the existing pump’s suitability for that system. For example, if the Delta-T is extremely small (2°F to 5°F), the pump is most likely too big.

See GSA’s Green Proving Ground for more details on the field demonstration findings.

What is this measure?

What Is This Measure?

Standard approaches to calcite mitigation rely on chemicals, which must be replenished frequently, or ultra-fine-membrane filtering, which uses large amounts of water and energy. Researchers assessing catalyst-based non-chemical water treatment (NCWT) at the Frank E. Moss Federal Courthouse in Salt Lake City, Utah, found that the technology dramatically reduced calcite buildup and had immediate payback when compared to a chemical (salt-based) system. The harder the water, the more likely non-chemical scale prevention will be cost-effective.

Special Considerations

• Initially, calcite buildup and overheating continued because the device was sized based on design flow rather than measured water flow. A flow test using ultrasonic meters should be used to determine appropriate device sizing.
• The technology was certified by the National Sanitation Foundation in 2013. Currently, there are approximately ten thousand U.S. installations.
• Remote locations, where access to power, chemicals, and labor makes conventional water softening impractical and expensive, may benefit particularly from this technology.

See GSA’s Green Proving Ground for more details on the field demonstration findings.