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Summary

Active Chilled Beam Heating and Cooling

Cooling Systems: Chilled Beams vs. Conventional VAV Air Distribution System

A heating and cooling system that draws room air past hot or cold water heat exchangers and provides conditioned air and necessary ventilation air into the space.

Synopsis:

Chilled beams are not structural building elements. A chilled beam is a hydronic convection HVAC component designed to heat or cool large buildings. Pipes of water pass through a "beam" (a casing with heat exchanger similar to a radiator or baseboard heater) that is either integrated into standard suspended ceiling systems or suspended a short distance from the ceiling of a room. As the beam chills the air around it, the air becomes denser and falls to the floor. It is replaced by warmer air that moves up from below, causing a constant flow of convection and cooling the room. 

Chilled beam systems can be passive or active. Active systems use supplemental ventilation air to distribute the cool air away from the beam. Active chilled beams use circulating fans to move room air to the beam’s heat exchange surface and provide fresh air for ventilation with small ducts. When compared to variable air volume (VAV) HVAC, these systems provide several benefits in medium to large commercial and public buildings, including energy savings.

Chilled beam systems have been installed in office buildings, hospitals and laboratories, K-12 schools, colleges and universities, and government buildings. Because water is a more efficient medium for heat transfer than air, HVAC energy savings up to 20% are possible. Chilled beam systems do not require conditioned air delivery to building spaces, eliminating the need for large supply and return air fans. Low-capacity pumps use less energy than large-capacity supply and return air fans, and duct losses are eliminated. Also, the chilled water for cooling has a higher temperature than conventional chilled air, extending the “free-cooling season.” A higher design chilled water temperature (58°F) may allow chiller efficiencies to increase by as much as 35%. 

Chilled beams are popular in Europe and the UK, in areas with climates similar to those found in the Northwest. Condensation on the chilled beam can be an issue that can be mitigated with dehumidification. Chilled beam systems require some provision for ventilation air and may also require supplemental heating and cooling – such as perimeter heating – in less moderate climates. Resolving  these issues can incur additional costs (Navigant Consulting, 2012). 

Energy Savings: 20%
Energy Savings Rating: Extensive 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.

Status: Next Steps based on Identification Stage (Stage Gate 1): Accept

Details

Active Chilled Beam Heating and Cooling

Cooling Systems: Chilled Beams vs. Conventional VAV Air Distribution System

A heating and cooling system that draws room air past hot or cold water heat exchangers and provides conditioned air and necessary ventilation air into the space.
Item ID: 316
Sector: Commercial
Energy System: HVAC--Other HVAC Systems
Technical Advisory Group: 2010 HVAC TAG (#3)
Technical Advisory Group: 2015-1 Commercial HVAC TAG (#11)
Average TAG Rating: 2.68 out of 5
TAG Ranking Date: 03/10/2015
TAG Rating Commentary:
  1. Can be applied in an efficient manner or an inefficient manner. Essentially these are fancy fan coils.
  2. While this technology is more suitable for new construction, it could be helpful to identify good retrofit applications and guidelines for estimating and verifying energy savings.
  3. Probably mostly a new construction or deep retrofit technology that would fall under a custom project.
  4. Not a panacea, but no high performance system is universal. Very high potential for commercial buildings, if its limitations are understood. Essentially requires DOAS, which is ok.
  5. I don't think there is a way to make this a retrofit measure. If I'm wrong, then i'm very interested.
  6. I support it even more when it is paired with DOAS

Synopsis:

Chilled beams are not structural building elements. A chilled beam is a hydronic convection HVAC component designed to heat or cool large buildings. Pipes of water pass through a "beam" (a casing with heat exchanger similar to a radiator or baseboard heater) that is either integrated into standard suspended ceiling systems or suspended a short distance from the ceiling of a room. As the beam chills the air around it, the air becomes denser and falls to the floor. It is replaced by warmer air that moves up from below, causing a constant flow of convection and cooling the room. 

Chilled beam systems can be passive or active. Active systems use supplemental ventilation air to distribute the cool air away from the beam. Active chilled beams use circulating fans to move room air to the beam’s heat exchange surface and provide fresh air for ventilation with small ducts. When compared to variable air volume (VAV) HVAC, these systems provide several benefits in medium to large commercial and public buildings, including energy savings.

Chilled beam systems have been installed in office buildings, hospitals and laboratories, K-12 schools, colleges and universities, and government buildings. Because water is a more efficient medium for heat transfer than air, HVAC energy savings up to 20% are possible. Chilled beam systems do not require conditioned air delivery to building spaces, eliminating the need for large supply and return air fans. Low-capacity pumps use less energy than large-capacity supply and return air fans, and duct losses are eliminated. Also, the chilled water for cooling has a higher temperature than conventional chilled air, extending the “free-cooling season.” A higher design chilled water temperature (58°F) may allow chiller efficiencies to increase by as much as 35%. 

Chilled beams are popular in Europe and the UK, in areas with climates similar to those found in the Northwest. Condensation on the chilled beam can be an issue that can be mitigated with dehumidification. Chilled beam systems require some provision for ventilation air and may also require supplemental heating and cooling – such as perimeter heating – in less moderate climates. Resolving  these issues can incur additional costs (Navigant Consulting, 2012). 

Baseline Example:

Baseline Description: Conventional HVAC cooling practices
Baseline Energy Use: 10.5 kWh per year per square foot

Comments:

The baseline is a conventional HVAC system using chillers, air handling units, and ductwork to deliver heating and cooling air to building zones. Chilled beam systems are appropriate for new construction and major building renovations. In these scenarios, the higher construction cost of the chilled beam system (beam terminals, chilled water piping, insulation, and pumps) can be offset through reductions in ductwork and sheet metal requirements, smaller air handling units, reduced mechanical room size, and reduced floor-to-floor heights, which lead to savings in wall and stair installation costs and elevator operating costs. Beams installed in the ceiling reduce ceiling tile costs. A uniform space temperature can be achieved while system noise is lower due to the absence of VAV boxes. 

The 2009 Commercial Building Stock Assessment ( NEEA, 12/21/2009) gives the building’s actual electrical Energy Use Index (EUI) for various types of heating and cooling systems (NEEA, 2009 Pg (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 values 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 but no electrical heating is 14.8 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).

Because this technology can be applied to many types of buildings, a baseline commercial building heating and cooling energy use of 10.5 kWh/sf/year is assumed (NEEA, 12/21/2009).

Manufacturer's Energy Savings Claims:

"Typical" Savings: 30%

Best Estimate of Energy Savings:

"Typical" Savings: 20%
Energy Savings Reliability: 4 - Extensive Assessment

Comments:

Based on a literature review conducted by the U.S. DOE Building Technologies Office, the estimated heating/cooling system energy savings are 20% when this system is compared to a standard VAV system (Navigant Consulting, 2012). Savings will vary depending on the application.

Energy Use of Emerging Technology:
8.4 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: 207,575,400
Comments:

This measure is a design strategy that can best be applied to new construction or major renovation. It is not a likely retrofit option for existing buildings. It could be applied to new commercial building construction, but must be integrated with compatible emerging technologies and compete with efficient advanced cooling technologies. CBSA data projects that commercial building square footage will grow approximately 1% annually. 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, new construction/renovations reflect about 3% of the existing building stock in a given year. Assuming that the next 10 years of construction represent the new construction/major renovation potential, this will affect34% of the existing commercial square footage: 3,118,000,000 sf less the square footage of buildings that are not good fits for this technology (including grocery stores = 84.6 million sf; restaurants = 42.3 million sf; warehouse space = 173.0 million sf; hotel/motel space = 117.6 million sf; and vacant buildings = 40.3 million sf). The result is a potential of 904,468,000 sf. Applying market shares from existing buildings, consider only conditioned square feet (85%) and electrically heated space (27%) = 904,468,000 x 0.85 x 0.27 = 207,575,400 sf. 

Regional Technical Potential:
0.44 TWh per year
50 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

Comments:

Harvey Sachs from ACEEE (Sachs, 2009)estimates that a chilled beam system will cost about 5% less than a conventional VAV HVAC system. This is likely due to cost savings from not needing an air distribution system. Costs will be higher in some applications that require supplemental heating or cooling or that have high ventilation loads (which may not be good applications for this technology).


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:

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

Syska Hennessy Group, 08/01/2007. Chilled Beam Ceiling Systems Promise Energy, Maintenance Savings
Syska Hennessy Group

FEMP, 10/04/2013. New and Underutilized Technology: Active Chilled Beam Cooling with Dedicated OSA Ventilation
United States Department of Energy, Office of Energy Efficiency and Renewable Energy, Federal Energy Management Program

FEMP, 07/27/2009. Chilled Beams in Laboratories: Key Strategies to Ensure Effective Design, Construction and Operation
United States Department of Energy, Office of Energy Efficiency and Renewable Energy, Federal Energy Management Program

Navigant Consulting, 10/01/2012. Energy Savings and RD&D Opportunities for Residential Building HVAC Systems
U.S. DOE Building Technologies Office
Special Notes: While this report focuses on residential technologies, it does review a variety of technologies, some of which apply to commercial buildings. See Appendix D for information on chilled beam systems. This report references Sachs 2009 study for information on chilled beam systems.

H. Sachs, 12/01/2009. Emerging Energy-Saving HVAC Technologies and Practices for the Building Sector
ACEEE

Rank & Scores

Active Chilled Beam Heating and Cooling

2015-1 Commercial HVAC TAG (#11)


Technical Advisory Group: 2015-1 Commercial HVAC TAG (#11)
TAG Ranking: 19 out of 29
Average TAG Rating: 2.68 out of 5
TAG Ranking Date: 03/10/2015
TAG Rating Commentary:

  1. Can be applied in an efficient manner or an inefficient manner. Essentially these are fancy fan coils.
  2. While this technology is more suitable for new construction, it could be helpful to identify good retrofit applications and guidelines for estimating and verifying energy savings.
  3. Probably mostly a new construction or deep retrofit technology that would fall under a custom project.
  4. Not a panacea, but no high performance system is universal. Very high potential for commercial buildings, if its limitations are understood. Essentially requires DOAS, which is ok.
  5. I don't think there is a way to make this a retrofit measure. If I'm wrong, then i'm very interested.
  6. I support it even more when it is paired with DOAS


2010 HVAC TAG (#3)


Technical Advisory Group: 2010 HVAC TAG (#3)
TAG Ranking:
Average TAG Rating:
TAG Ranking Date:
TAG Rating Commentary:

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