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Summary

Low Temperature Variable Refrigerant Flow (VRF) with or without Simultaneous Heating and Cooling for Large Commercial Applications

Low Temperature Variable Refrigerant Flow (VRF) Systems: Low Temperature VRF Heating and Cooling vs. Code Minimum HVAC

Variable refrigerant flow systems for large commercial buildings, similar to ID #126, but designed specifically for climates with frequent low temperatures so that auxiliary heat is not needed, or is needed only at very low temperatures.

Synopsis:

Traditional heat pumps loose their efficiency and ability to work at low outside air temperatures, the actual minimum temperature depending on manufacturer.  At low outdoor temperatures, the traditional heat pumps resort to inefficient electric strip heaters.  The equipment proposed here, however, is superior as it can still provide heat pump heating (aka, compression heating) at temperatures down around -25 degrees.

This technology can be installed with or without simultaneous heating and cooling.   Systems without heat transfer between zones are appropriate in applications where all the zones act similarly, such as an auditorium or a row of classrooms with similar exterior exposures.  Systems with heat transfer between zones cost a little more than the system without simultaneous heating and cooling and would be appropriate in an application where some zones are in heat mode while some are in cooling mode, such as an apartment building, office building, etc, with dissimilar exterior exposures and/or dissimilar uses.   

Since about 2006, low temperature heat pumps (LTHPs) have been a standard offering in the U.S. from many manufacturers. Unlike standard heat pumps, the cold climate heat pump provides efficient heating capacity even at -25 degrees F.  This equipment is also more sturdy, resulting in more reliability.

On new construction, other benefits include reduced building heights since ductwork can be minimized and reduced building electric service and wire sizes since all HVAC is 'soft' start.

Energy Savings: 25%
Energy Savings Rating: Comprehensive Analysis  What's this?
LevelStatusDescription
1Concept not validatedClaims of energy savings may not be credible due to lack of documentation or validation by unbiased experts.
2Concept validated:An unbiased expert has validated efficiency concepts through technical review and calculations based on engineering principles.
3Limited assessmentAn unbiased expert has measured technology characteristics and factors of energy use through one or more tests in typical applications with a clear baseline.
4Extensive assessmentAdditional testing in relevant applications and environments has increased knowledge of performance across a broad range of products, applications, and system conditions.
5Comprehensive analysisResults of lab and field tests have been used to develop methods for reliable prediction of performance across the range of intended applications.
6Approved measureProtocols for technology application are established and approved.

Status:

Details

Low Temperature Variable Refrigerant Flow (VRF) with or without Simultaneous Heating and Cooling for Large Commercial Applications

Low Temperature Variable Refrigerant Flow (VRF) Systems: Low Temperature VRF Heating and Cooling vs. Code Minimum HVAC

Variable refrigerant flow systems for large commercial buildings, similar to ID #126, but designed specifically for climates with frequent low temperatures so that auxiliary heat is not needed, or is needed only at very low temperatures.
Item ID: 311
Sector: Commercial
Energy System: HVAC--Heat Pumps

Synopsis:

Traditional heat pumps loose their efficiency and ability to work at low outside air temperatures, the actual minimum temperature depending on manufacturer.  At low outdoor temperatures, the traditional heat pumps resort to inefficient electric strip heaters.  The equipment proposed here, however, is superior as it can still provide heat pump heating (aka, compression heating) at temperatures down around -25 degrees.

This technology can be installed with or without simultaneous heating and cooling.   Systems without heat transfer between zones are appropriate in applications where all the zones act similarly, such as an auditorium or a row of classrooms with similar exterior exposures.  Systems with heat transfer between zones cost a little more than the system without simultaneous heating and cooling and would be appropriate in an application where some zones are in heat mode while some are in cooling mode, such as an apartment building, office building, etc, with dissimilar exterior exposures and/or dissimilar uses.   

Since about 2006, low temperature heat pumps (LTHPs) have been a standard offering in the U.S. from many manufacturers. Unlike standard heat pumps, the cold climate heat pump provides efficient heating capacity even at -25 degrees F.  This equipment is also more sturdy, resulting in more reliability.

On new construction, other benefits include reduced building heights since ductwork can be minimized and reduced building electric service and wire sizes since all HVAC is 'soft' start.

Baseline Example:

Baseline Description: Code minimum HVAC
Baseline Energy Use: 10.5 kWh per year per square foot

Comments:

The 2009 Commercial Building Stock Assessment gives the actual electrical building EUI's for various types of heating and cooling systems (Table D-EA5).  Office buildings with electric heating and cooling have an EUI of 20.1 kWh/sf-year.  Office buildings with no electric heating or cooling use only 8.2 kWh/sf-year, indicating that the combined HVAC heating and cooling energy use is 11.9 kWh/sf-year.  (For all commercial buildings, the corresponding numbers are 19.9 and 9.4 kWh/sf-year, respectively). Since this technology can be applied to many types of non-office buildings, a baseline energy use of 10.5 kWh/sf-year is assumed (NEEA, 2009).

Manufacturer's Energy Savings Claims: Currently no data available.
Best Estimate of Energy Savings:

"Typical" Savings: 25%
Low and High Energy Savings: 15% to 40%
Energy Savings Reliability: 5 - Comprehensive Analysis

Comments:

The efficiency of this ET is 100% at 0 degrees, and 75% at -20 degrees.  The baseline is 100% at 20 degrees and 75% at 0 degrees, using strip heat to supplement the code minimum heat pump when it cannot meet the load.  The estimate is for a climate that sees outside air temperatures below 20 degrees about 10% of the hours per year.

Energy Use of Emerging Technology:
7.9 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: 123,956,000
Comments:

This technology could technically be used for conditioned space in virtually any commercial building, so we are using the total of the entire commercial building stock in the Northwest. The numbers are taken from preliminary updated numbers from the 2013 update to the Commercial Building Stock Assessment (CBSA) using the estimates for 2014 (before the update was completed -- from early January, 2014) multiplied times the percentage of commercial space that is conditioned based on the 2009 CBSA. It is not appropriate for small single-zone buildings, which we approximate as those buildings with less than 5000 sf (10% of all space), nor is it appropriate for buildings with high ceilings, such as big box stores. This is taken to be buildings of those types between about 20,000 and 200,000 sf, or about 50% of retail and grocery space. We can only count electrically-heated buildings for the purposes of BPA savings potential. According to the CBSA, about 30% of commercial buildings are heated with electricity. Finally, the low-temperature heat pumps will mostly apply to BPA heating zones 2 and 3 (greater than 6000 heating degree days), or 20% of the Northwest population. We assume that the commercial space and its characteristics are essentially proportional to the population.

Commercial Floor Space Appropriate for VRF with Internal and External Heat Recovery in Cold Climate Zones

 Total Floor space   -s.f. Warehouse   non-Warehouse   % Conditioned   -% Sm. (>5K)   Applicable Space   50% Retail & Groc.   Appropriate Space  Elect. Ht.  Cold Climate 
 Source   (NEEA, 2014)  (NEEA, 2009 App C)  (NEEA, 2009 App C)    
 3,118,000,000  173,000,000  2,945,000,000       87.0%       10%      2,305,935,000    240,000,000  2,065,935,000  619,780,000  123,956,000
Regional Technical Potential:
0.33 TWh per year
37 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: Currently no data available.

Cost Effectiveness:

Simple payback, new construction (years): N/A

Simple payback, retrofit (years): N/A

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.

Reference and Citations:

WSU EEP, 12/12/2013. Variable Refrigerant Flow Q&A
Washington State University Extension Energy 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

Rank & Scores

Low Temperature Variable Refrigerant Flow (VRF) with or without Simultaneous Heating and Cooling for Large Commercial Applications

There is no TAG available for this technology.
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