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Summary

Low-Lift Cooling Technology Option Set

Cooling Systems: Set of Advanced Cooling Technologies vs. Conventional

A set of five technologies based on low-lift vapor compression cooling equipment assembled by Pacific Northwest National Laboratory (PNNL) under a single name.

Synopsis:

This is a technology option set first proposed by Pacific Northwest National Laboratory (PNNL) in 2007 in as part of DOE’s effort to achieve net Zero Energy Buildings in the commercial sector. It is actually a set of five strategies, with low-lift cooling central to its success. The five strategies are:

1. Peak-load shifting by means of active or passive thermal energy storage (TES)
2. Dedicated outdoor air supply with enthalpy heat recovery from exhaust air.
3. Radiant heating and cooling panels or floor system.
4. Low-lift vapor compression cooling equipment.
5. Advanced controls at the HVAC equipment and HVAC system (supervisory) levels.

The strategy is built with existing commercially –available equipment, but as of the fall of 2011, no one is offering this as an assembled package. The work on this so far has been with modeling. The results look promising, with energy savings as high as 74% in the right application. PNNL is preparing to do field studies – scoping out the project and seeking funding and test locations.

A note of caution, however: not all chillers can easily accept low-lift conditions. For example, some large chillers cannot operate below 30% of maximum flow. Therefore, this strategy requires a good understanding of the technologies being employed.

Energy Savings: 42%
Energy Savings Rating: Limited Assessment  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.
Simple Payback, New Construction (years): 2.9   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.

Status:

Details

Low-Lift Cooling Technology Option Set

Cooling Systems: Set of Advanced Cooling Technologies vs. Conventional

A set of five technologies based on low-lift vapor compression cooling equipment assembled by Pacific Northwest National Laboratory (PNNL) under a single name.
Item ID: 184
Sector: Commercial
Energy System: HVAC--Other HVAC Systems
Technical Advisory Group: 2009 HVAC TAG (#2)

Synopsis:

This is a technology option set first proposed by Pacific Northwest National Laboratory (PNNL) in 2007 in as part of DOE’s effort to achieve net Zero Energy Buildings in the commercial sector. It is actually a set of five strategies, with low-lift cooling central to its success. The five strategies are:

1. Peak-load shifting by means of active or passive thermal energy storage (TES)
2. Dedicated outdoor air supply with enthalpy heat recovery from exhaust air.
3. Radiant heating and cooling panels or floor system.
4. Low-lift vapor compression cooling equipment.
5. Advanced controls at the HVAC equipment and HVAC system (supervisory) levels.

The strategy is built with existing commercially –available equipment, but as of the fall of 2011, no one is offering this as an assembled package. The work on this so far has been with modeling. The results look promising, with energy savings as high as 74% in the right application. PNNL is preparing to do field studies – scoping out the project and seeking funding and test locations.

A note of caution, however: not all chillers can easily accept low-lift conditions. For example, some large chillers cannot operate below 30% of maximum flow. Therefore, this strategy requires a good understanding of the technologies being employed.

Baseline Example:

Baseline Description: No Thermal Energy Storage, No DOAS, No Radiant Cooling, Hermetic Chiller and Standard Controls
Baseline Energy Use: 6.6 kWh per year per square foot

Comments:

The 2009 Commercial Building Stock Assessment gives the actual electrical building energy use index(EUI) 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 for a heating and cooling use of 10.5 kWh/sf-year.

Commercial buildings with electric cooling and with no electric heating have an electrical EUI of 16.8 kWh/sf-year (14.8 for office buildings).  This indicates that the heating load for all categories of commercial buildings is about 3.1 kWh/sf-year (19.9-16.8) with a cooling load of about 7.4 kWh/sf-year (10.5-3.1).  The corresponding electrical EUI for office buildings with electric cooling with no electrical heating is14.8 kWh/sf-year which indicates a space heating load of 5.3 kWh/sf-year with a corresponding cooling load of 6.6 kWh/sf-year (11.9-5.3).  

Since this technology can be applied to many types of office buildings, a baseline cooling energy use of 6.6 kWh/sf/year is assumed (NEEA,12/21/2009).

Manufacturer's Energy Savings Claims:

Comments:

This is a strategy encompassing five design elements.  Therefore, there are no manufacturers claims.

Best Estimate of Energy Savings:

"Typical" Savings: 42%
Low and High Energy Savings: 1% to 85%
Energy Savings Reliability: 3 - Limited Assessment

Comments:

PNNL (Katipamula, et al., 2010) did extensive modeling to show that this strategy will save about 42% of the cooling energy, on the average.

Energy Use of Emerging Technology:
3.8 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: 168,510,000
Comments:

The low-lift technology option set is best applied to new construction or major renovations. It is not a retrofit that would be applied to existing buildings. The best market appears to be large and medium size office buildings (Katipamula, 2010).

CBSA data ( Ecotope, Inc., 01/01/2014) includes projections of commercial building square footage. For office buildings this growth rate is approximately 1.5%. If we assume existing buildings have a 50 year life, then 2% of buildings will be replaced or have major renovations in a given year. Thus in any given year, new construction or major renovations will be ~3.5% of the existing building stock. Assuming the next 10 years of construction represents the new construction/major renovation potential results in 41% of the existing office building square footage: 411,000,000 * 0.41 = 168,510,000.

Regional Technical Potential:
0.47 TWh per year
53 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): $8.71
Baseline Technology Unit Cost (Equipment Only): $7.99

Comments:

It is difficult to estimate the costs of applying low-lift cooling technology because it is not a single piece of equipment, but applies a combination of technologies and the costs will be dependent on how the technologies are applied and the requirements of each specific application. The PNNL study (Katipamula, 2010) estimated costs for baseline and low-lift cooling systems. For the medium office building the baseline cost was $507,000 and for the low lift $472,000. For the large office building the baseline was $3,982,000 and for the low-lift $4,345,000. Assuming these estimates are for the prototype large office building of 498,588 sf, then these costs are $7.99 and $8.71 per sf.

Cost Effectiveness:

Simple payback, new construction (years): 2.9

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:

Srinivas Katipamula, 1/1/2010. Cost-Effective Integration of Efficient Low-Lift Baseload Cooling Equipment
Pacific Northwest National Laboratory

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

Srinivas Katipamula, 03/10/2010. Development of High-Efficiency Low-Lift Vapor Compression System – Final Report
Pacific Northwest National Laboratory

xx, 09/01/2015. xx
xx

Rank & Scores

Low-Lift Cooling Technology Option Set

2009 HVAC TAG (#2)


Technical Advisory Group: 2009 HVAC TAG (#2)
TAG Ranking:
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