ECPM Motors for Single-phase HVAC Fan Applications

Summary

ECPM Motors for Single-phase HVAC Fan Applications

HVAC Fan Motors: Electronically Commutated Permanent Magnet (ECPM) vs. Permanent Split Capacitor (PSC) or Shaded-pole Constant-speed Motor

High efficiency electronically commutated permanent magnet (ECPM) motors with inherent variable speed capability that are ideal retrofits for package terminal air conditioners, room air conditioners, unitary condenser fans and blowers, and exhaust fan applications.

Synopsis:

Electronically commutated permanent magnet (ECPM) motors always have higher efficiencies than conventional single-phase, fractional horsepower induction motors because they do not suffer resistance losses from current flow in aluminum rotor bars. As smaller motors have higher losses than larger motors, research in the 1990s focused on small ECPM motor design and optimization. This assessment focuses on programmable ECPM motors that are used for indoor blowers and outdoor fans driven by 1/15, 1/10, 1/5, 1/3, ½, ¾, and 1 horsepower motors. These ECPM motors have much higher full-load efficiencies than standard or conventional capacitor start/induction run and capacitor start/capacitor run (PSC) motors. They come with integral controllers or electronic inverters that can control both motor speed and torque, which can result in far greater energy savings in many applications compared with conventional constant-speed motors.

A review of manufacturer’s literature for fractional horsepower ECPM motors supplied by Marathon, Genteq, and QM Power indicates that full-load efficiencies fall in the range of 78% to 82%. The typical maximum efficiency of a multi-speed PSC motor is around 60% at rated full-load speed (Beloit, 2010). ECPM motors hold their high efficiency when lightly loaded, operating near 80% efficiency across the motor’s entire operating range (Beloit, 2010). At part-loads, the differences in efficiency between the variable-speed ECPM and standard motors grows in favor of the ECPM motor. As ECPM motors feature inherent variable speed capability, energy savings are substantial in applications with fluctuating load requirements.

ECPM motors are increasingly being recommended or required in city or state energy codes for some single-phase evaporator and condenser fan units, or fractional or integral horsepower series fan terminal units, swimming pool pumps, and circulating hot or chilled water pumps. With these systems, hot water, air, or refrigerant is circulated through a heat exchanger to condition a space. Energy savings of 20% to over 70% can occur when ECPM motors are used to replace conventional fractional hp single-phase PSC fan or blower drive motors.

ECPM motors could also be used in residential equipment, although the savings may be less because more residential fans are multi-speed and thus the addition of variable-speed motors wouldn’t be as much. Furthermore, this is less cost-effective due to the additional costs of programming the ECPM motor to duplicate the performance of a multi-speed baseline motor.

In commercial variable air volume (VAV) applications, ECPM motors may be equipped with voltage feedback control (0-10 VDC) from sensors so constant pressure or constant air flow operation can be provided. Good duct design and clean filters are important for ECPM operation. With a permanent split capacitor (PSC) motor-driven blower, an airflow restriction (such as a clogged filter) has much the same impact as a discharge damper: airflow and motor input power are reduced. With an ECPM motor, the motor speed increases to maintain a constant airflow, resulting in an input power requirement that may exceed that of the old PSC motor.

ECPM motors can also be employed to control fans used in package terminal air conditioners, room air conditioners, unitary condenser fans and blowers, and exhaust fan applications commonly found in commercial buildings. With these systems, hot water, air, or refrigerant is circulated through a heat exchanger to condition a space. Energy savings of 20% to 33% typically occur when ECPM motors are used to replace conventional fractional hp single-phase PSC fan or blower drive motors.

Energy Savings: 33%

Energy Savings Rating: Comprehensive Analysis What's this?

Level	Status	Description
1	Concept not validated	Claims of energy savings may not be credible due to lack of documentation or validation by unbiased experts.
2	Concept validated:	An unbiased expert has validated efficiency concepts through technical review and calculations based on engineering principles.
3	Limited assessment	An unbiased expert has measured technology characteristics and factors of energy use through one or more tests in typical applications with a clear baseline.
4	Extensive assessment	Additional testing in relevant applications and environments has increased knowledge of performance across a broad range of products, applications, and system conditions.
5	Comprehensive analysis	Results of lab and field tests have been used to develop methods for reliable prediction of performance across the range of intended applications.
6	Approved measure	Protocols for technology application are established and approved.

Simple Payback, New Construction (years): 6.5 What's this?

Simple Payback, Retrofit (years): 10.2 What's this?

Simple Payback is one tool used to estimate the cost-effectiveness of a proposed investment, such as the investment in an energy efficient technology. Simple payback indicates how many years it will take for the initial investment to "pay itself back." The basic formula for calculating a simple payback is:

Simple Payback = Incremental First Cost / Annual Savings

The Incremental Cost is determined by subtracting the Baseline First Cost from the Measure First Cost.

For New Construction, the Baseline First Cost is the cost to purchase the standard practice technology. The Measure First Cost is the cost of the alternative, more energy efficienct technology. Installation costs are not included, as it is assumed that installation costs are approximately the same for the Baseline and the Emerging Technology.

For Retrofit scenarios, the Baseline First Cost is $0, since the baseline scenario is to leave the existing equipment in place. The Emerging Technology First Cost is the Measure First Cost plus Installation Cost (the cost of the replacement technology, plus the labor cost to install it). Retrofit scenarios generally have a higher First Cost and longer Simple Paybacks than New Construction scenarios.

Simple Paybacks are called "simple" because they do not include details such as the time value of money or inflation, and often do not include operations and maintenance (O&M) costs or end-of-life disposal costs. However, they can still provide a powerful tool for a quick assessment of a proposed measure. These paybacks are rough estimates based upon best available data, and should be treated with caution. For major financial decisions, it is suggested that a full Lifecycle Cost Analysis be performed which includes the unique details of your situation.

The energy savings estimates are based upon an electric rate of $.09/kWh, and are calculated by comparing the range of estimated energy savings to the baseline energy use. For most technologies, this results in "Typical," "Fast" and "Slow" payback estimates, corresponding with the "Typical," "High" and "Low" estimates of energy savings, respectively.

Details

ECPM Motors for Single-phase HVAC Fan Applications

HVAC Fan Motors: Electronically Commutated Permanent Magnet (ECPM) vs. Permanent Split Capacitor (PSC) or Shaded-pole Constant-speed Motor

Item ID: 101

Sector: Residential, Commercial

Energy System: HVAC--Rooftop Units & Air Handling Units

Technical Advisory Group: 2010 HVAC TAG (#3)
Average TAG Rating: 2.8 out of 5
TAG Ranking Date: 06/29/2010
TAG Rating Commentary:

I think California will have this one covered.
Would like to find out more about the NovaTorque motor. Sounds like a retrofit opportunity. May be difficult to specify as OEM equipment.
How does this compare to a standard ECPM motor?
Great technology. But NovaTorque needs to be adopted by package unit manufacturers before it can have significant market penetration. Otherwise they will need to develop control packages that could make retrofitting the motor possible to existing equipment.
Would be good to vet the claims, but leery of trying to support such a proprietary technology - shouldn't the manufacturer be the one expending capital to demonstrate the savings?

Technical Advisory Group: 2009 HVAC TAG (#2)

Technical Advisory Group: 2015-1 Commercial HVAC TAG (#11)
Average TAG Rating: 3.74 out of 5
TAG Ranking Date: 03/10/2015
TAG Rating Commentary:

I don't think there are non-energy benefits to motivate contractors to motivate ECPM installations - especially replacing operating motors. It could be helpful to identify non-energy benefits, good retrofit applications and guidelines for estimating and verifying energy savings.
I believe that this is effectively required by the DOE furnace fan rule taking effect in 2019. Programs now are worth considering - but given total cost (including installation) for new equipment the constant-speed ECM may be a better value, while the constant torque that will be required in 2019 could lead to great programs for replacing PSC air handler motors when they fail. This is probably better suited to upstream incentives than consumer ones - fan motor failures are emergency repairs.
The ECPM or DC brushless motors are more efficient, easier to control and last longer, but high static pressure or other HVAC system problems can diminish the savings.
Hard to beat the success of this technology, especially if it is offered as a drop-in replacement for existing split capacitor motors.

Synopsis:

Baseline Example:

Baseline Description: 1/4 hp PSC constant-speed motor-driven fan
Baseline Energy Use: 2.8 kWh per year per square foot

Comments:

The baseline powerdraw for a constant speed ¼ hp PSC motor is about 0.37 kW (assuming a 50%operating efficiency). The energy use for a baseline fan drive motor thatoperates 2,500 hours per year is 932 kWh/yr. A 1/4 hp fan will typicallyserve about 333 sf of conditioned floor area, so the baseline energy useis about 2.8 kWh/sf/year.

Manufacturer's Energy Savings Claims:

"Typical" Savings: 50%
Savings Range: From 20% to 86%

Comments:

Swapping out a straight induction motor with an ECPM motor in a unit ventilator application can produce energy savings of 50% due to the variable speed capability of the PM motor and its inherently higher part-load efficiency. Savings are further improved when demand-controlled ventilation and occupancy sensor control are added; these useful additions are well supported by ECPM’s variable speed capability.

The savings range of 20% to 86% is over a PSC motor.

Best Estimate of Energy Savings:

"Typical" Savings: 33%
Low and High Energy Savings: 11% to 70%
Energy Savings Reliability: 5 - Comprehensive Analysis

Comments:

Energy savings occur due to two mechanisms. First, ECPM motors offer superior full- and part-load efficiency relative to conventional AC motors in the fractional hp sizes. Second, ECPM motors behave like DC motors in that their speed is proportional to voltage while torque is proportional to current (Roth, et. al., 2002). Their inherent variable speed capability provides flow control while eliminating cycling losses or losses due to throttling valves or dampers.

The efficiency of the variable-speed ECPM motor is now required in the building codes for many types of small systems. The energy savings are well documented. A "Unit Ventilator VSD Energy Analysis" (EME Group Consulting Engineers, 2004) sponsored by New York State Energy Research and Development Authority (NYSERDA) found fan energy savings of 44% when ECPMs were applied in conjunction with thermostatically controlled steam valves on unit ventilators that utilized 1/8 hp motors.

The U.S. Department of Energy (USDOE) found that the full-load efficiency of ECPM motors between 1/4 and 1/2 hp is about 82% compared to a PSC motor full-load efficiency of 67%. This leads to an efficiency improvement of (1 – 67/82) x 100% = 18.3% at full load, with greater savings at part load. Additional energy savings occur when the variable speed capability of the ECPM motor is utilized (Roth, et. al., 2002). Energy savings are estimated at 33% for unitary condenser fans and blowers and PTAC blowers when using an ECPM motor's variable speed capability rather than a single-speed induction motor. Note that shaded pole motors can have an operating efficiency as low as 20% (DTE Energy, 2012).

Energy Use of Emerging Technology:

1.9 kWh per square foot per year What's this?

Energy Use of an Emerging Technology is based upon the following algorithm.

Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))

Technical Potential:
Units: square foot
Potential number of units replaced by this technology: 2,640,946,000
Comments:

This technology could be used for virtually any commercial building, so the entire commercial building stock in the Northwest is used for this analysis. Since the analysis below doesn’t include the area of residences in the region because this technology is less cost-effective in residential applications (see Synopsis above for details), it is somewhat conservative. For larger buildings, supply, return, and exhaust fans are driven by integral hp induction motors, often equipped with adjustable speed drives. Integral hp motors account for 80% of all commercial HVAC energy consumption; fractional hp motors account for the remaining 20% (Roth, et. al., 2002). ECPM motors can be installed in terminal boxes when a variable air volume system is employed.

The preliminary updated numbers below are from the 2013 update to the Commercial Building Stock Assessment (CBSA). The estimates for 2014 (from early January 2014 – before the update was completed) were multiplied by the percentage of commercial space that is conditioned based on the 2009 CBSA. Note: Building codes now require the use of VSD or ECPM technologies when loads are variable. It is not known what percentage of applications already employ this type of fan speed control, but the actual technical potential would be somewhat less than that stated.

	Total Commercial Floor space (sf)	% Conditioned	Conditioned space (sf)
Source	(NEEA, 2014)	(NEEA, 2009, App C)
	3,118,000,000	84.7%	2,640,946,000

Regional Technical Potential:
2.44 TWh per year
279 aMW
What's this?

Regional Technical Potential of an Emerging Technology is calculated as follows:

Baseline Energy Use * Estimate of Energy Savings (either Typical savings OR the high range of savings) * Technical Potential (potential number of units replaced by the Emerging Technology)

First Cost:

Installed first cost per: square foot
Emerging Technology Unit Cost (Equipment Only): $0.55
Emerging Technology Installation Cost (Labor, Disposal, Etc.): $0.30
Baseline Technology Unit Cost (Equipment Only): $0.01

Comments:

Note that the cost data above represents the incremental costs based on credible and detailed field studies that are needed to calculate cost-effectiveness. However, this data does not accurately represent the actual cost of the motors because that data is quite variable based on many factors and difficult to obtain.

Cost Effectiveness:

Simple payback, new construction (years): 6.5

Simple payback, retrofit (years): 10.2

What's this?

Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.

Comments:

Evidence suggests that ECPM motors can offer simple payback periods as low as 2.5 years in commercial HVAC applications. The biggest variables are annual operating hours, utility rates, and the motor duty cycle or load profile. ECPM motor costs have greatly declined in recent years.

Operators are encouraged to examine the incremental costs over a conventional operating motor (or replacement motor when the motor has failed) versus the incremental energy savings. Replacing a failed motor makes better economic sense than replacing an operating motor. Because the failed motor must be changed out anyway, no installation charge is levied and only the incremental cost of the new motor is used in the cost-effectiveness analysis.

A study completed for the California Statewide Utility Codes and Standards Program indicates that the incremental cost of a ½ hp motor is $160 (Taylor Engineering, 2011). There is an economy of scale because a 1/8^th hp motor might have approximately the same incremental cost ($170 to $185). A ¼ hp motor would have an incremental cost of $130 to $140, or about $182 with contractor markup. The California analysis assumes a base case motor efficiency of 29% (very low, possibly a shaded-pole motor) with an ECPM motor efficiency of 69%. An additional startup/commissioning cost of $100 is assumed as part of installation costs. Full costs of ECM motors can be obtained from manufacturers’ equipment catalogs, such as Grainger.

The incremental cost is equivalent to an equipment cost of $182/333 sf or $0.55/sf, with a startup installation and commissioning cost of $0.30/sf.

Reference and Citations:

CMHC, 06/01/2009. Effects of ECPM Furnace Motors on Electricity and Gas Use
Canada Mortgage and Housing Corporation: Research Highlight

R&D, 08/08/2012. Permanent Magnet Produces Motor Efficiencies
R&D Magazine

ADM Associates, 12/01/2010. Nova Torque Brushless Permanent Magnet Motor Bench Test: Final Report
Sacramento Municipal Utility District

Kurt Roth, et. al., 07/01/2002. Energy Consumption Characteristics of Commercial Building HVAC Systems Volume III: Energy Savings Potential
Prepared by TIAX LLC for the U.S. DOE Building Technologies Program

NEEA, 01/01/2014. Total Pacific Northwest Building Stock Based on Preliminary Numbers from the 2013 Update to the CBSA
Northwest Energy Efficiency Alliance

CADMUS, 12/21/2009. Northwest Commercial Building Stock Assessment (CBSA): Final Report
Prepared by the CADMUS Group for the Northwest Energy Efficiency Alliance

EME Group Consulting Engineers, 06/30/2004. Unit Ventilator VSD Energy Analysis
New York State Energy Research & Development Authority (NYSERDA)

Taylor Engineering, 08/17/2011. ASHRAE 6 ECM Motors: August 17th CEC Workshop
California Energy Commission

DTE Energy, 03/01/2012. Case Study: Save-A-Lot Food Stores
DTE Energy’s Energy Efficiency Program for Business

PWA, 2015. ECM Motors for HVAC
PWA Engineering, LLC

Regal Beloit, 2010. ECM Textbook: History of ECM
Genteq , v. 3.0 Technical Manual

Rank & Scores

ECPM Motors for Single-phase HVAC Fan Applications

2015-1 Commercial HVAC TAG (#11)

Technical Advisory Group: 2015-1 Commercial HVAC TAG (#11)
TAG Ranking: 1 out of 29
Average TAG Rating: 3.74 out of 5
TAG Ranking Date: 03/10/2015
TAG Rating Commentary:

I don't think there are non-energy benefits to motivate contractors to motivate ECPM installations - especially replacing operating motors. It could be helpful to identify non-energy benefits, good retrofit applications and guidelines for estimating and verifying energy savings.
I believe that this is effectively required by the DOE furnace fan rule taking effect in 2019. Programs now are worth considering - but given total cost (including installation) for new equipment the constant-speed ECM may be a better value, while the constant torque that will be required in 2019 could lead to great programs for replacing PSC air handler motors when they fail. This is probably better suited to upstream incentives than consumer ones - fan motor failures are emergency repairs.
The ECPM or DC brushless motors are more efficient, easier to control and last longer, but high static pressure or other HVAC system problems can diminish the savings.
Hard to beat the success of this technology, especially if it is offered as a drop-in replacement for existing split capacitor motors.

2010 HVAC TAG (#3)

Technical Advisory Group: 2010 HVAC TAG (#3)
TAG Ranking: 16 out of 36
Average TAG Rating: 2.8 out of 5
TAG Ranking Date: 06/29/2010
TAG Rating Commentary:

I think California will have this one covered.
Would like to find out more about the NovaTorque motor. Sounds like a retrofit opportunity. May be difficult to specify as OEM equipment.
How does this compare to a standard ECPM motor?
Great technology. But NovaTorque needs to be adopted by package unit manufacturers before it can have significant market penetration. Otherwise they will need to develop control packages that could make retrofitting the motor possible to existing equipment.
Would be good to vet the claims, but leery of trying to support such a proprietary technology - shouldn't the manufacturer be the one expending capital to demonstrate the savings?

2009 HVAC TAG (#2)

Technical Advisory Group: 2009 HVAC TAG (#2)
TAG Ranking:
Average TAG Rating:
TAG Ranking Date:
TAG Rating Commentary: