Phase-change Materials

Summary

Phase-change Materials

Drywall: Phase-Change vs. Conventional

Building materials with phase-change properties that increases their effective thermal mass for thermal energy control and storage.

Synopsis:

A phase-change material (PCM) is a substance with a high heat of fusion. When melting and solidifying at a certain temperature, these materials are capable of storing and releasing large amounts of energy. When such a material freezes, it releases large amounts of energy in the form of latent heat of fusion, or energy of crystallisation. Conversely, when the material is melted, an equal amount of energy is absorbed from the immediate environment as it changes from solid to liquid.

This property of PCMs can be used in a number of ways, such as thermal energy storage whereby heat or coolness can be stored from one process or period in time, and used at a later date or different location. The simplest, cheapest, and most effective phase change material is water/ice. A number of different materials---including eutectics, salt hydrates, and organic materials--- have been developed to offer products that freeze and melt like water/ice, but at temperatures from the cryogenic range to several hundred degrees centigrade.

The energy storage and release cycle can be daily, weekly or seasonal depending on the system design requirements. The output is always be thermal energy, but the input may be thermal or electrical energy. Thermal storage may provide "free cooling"
by operating cooling towers during the night, freezing the PCM energy storage, so it can provide cooling as it melts during the day. Thermal storage has long been known and can be cost-effective when used for peak demand clipping and in utility areas with time-of-day electrical rates.

Energy Savings: 15%

Energy Savings Rating: Not rated. 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.

Details

Phase-change Materials

Drywall: Phase-Change vs. Conventional

Building materials with phase-change properties that increases their effective thermal mass for thermal energy control and storage.

Item ID: 229

Sector: Residential, Commercial, Industrial

Energy System: Building Envelope--Walls, Roof, & Floors

Technical Advisory Group: 2014 Commercial Building TAG (#9)
Average TAG Rating: 3 out of 5
TAG Ranking Date: 03/17/2014
TAG Rating Commentary:

Concept is potentially useful for energy management - in both cooling and heating seasons. The devil is in the details- what materials, what properties, what application, how is the HVAC managed.
There is evidence in multiple efforts that we have been involved with that there is potential with this technology.
Incremental costs are now quite low and it can be bundled with insulation and installed all at once, which offers key cost advantages.
A fantastic regional fit given our climate, and one without the necessary aesthetic burden of some of the other material solutions. This is a proven technology with a wide variety of applications.
Cost appears to still be a barrier; may be a more applicable technology to thermal energy storage

Technical Advisory Group: 2014 Residential Building TAG (#10)
Average TAG Rating: 2.76 out of 5
TAG Ranking Date: 04/10/2014
TAG Rating Commentary:

I do have some confusion in the detailed page. It says low incremental cost but that cost is still a barrier. That makes it sound like a reasonable incentive could have an impact on adoption. Also good addition to a new construction package. Maybe even a retrofit(?).
Has potential, but seems as though it is highly dependent on other variables such as HVAC utilization.
Not clear how this is significantly more valuable than double-layers sheetrock or other thermal mass increasing designs.

Synopsis:

Baseline Example:

Baseline Description: Existing Commercial Buildings
Baseline Energy Use: 7.4 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 commercial buildings, a baseline cooling energy use of 7.4 kWh/sf/year is assumed (NEEA,12/21/2009).

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

Best Estimate of Energy Savings:

"Typical" Savings: 15%
Low and High Energy Savings: 7% to 20%

Comments:

NREL conducted an investigation of phase-change materials in a single-story ranch house in several Southern Cities including Atlanta, Bakersfield, Fort Worth, Miami, and Phoenix. They found that materials selection, dispersion, and quantity of phase change material was critical in terms of peak load reductions and for energy savings (Kosny, 2013). They also conducted a literature review and report that PCM-enhanced gypsum boards in walls can provide cooling energy savings ranging between 7% and 20% in different locations. No studies are listed for Northwest locations.

"In some southern European climates, for example, the materials absorb enough heat during the day to save 20 percent of the electricity needed for air-conditioning. In northern Europe, where nighttime temperatures are cooler, a building incorporating the materials may not need an air conditioner at all", says Peter Schossig, an engineer at the Fraunhofer Institute in Munich, Germany.

It will be assumed that PCM system design will achieve a cooling load reduction of 15% in Northwest buildings.

Energy Use of Emerging Technology:

6.3 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 technically be used for 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.

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

Regional Technical Potential:
2.93 TWh per year
335 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:

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

Katherine Bourzac, 02/04/2010. "Melting" Drywall Keeps Rooms Cool
MIT - Technology Review

C. Castellón, 01/01/2007. Use of Microencapsulated Phase Change Materials in Building Applications
Oak Ridge National Laboratory

Corina Stetiu, 11/20/1998. Phase-Change Wallboard and Mechanical Night Ventilation in Commercial Buildings
Lawrence Berkeley National Laboratory

madrimasd, 08/01/2012. Energy Efficiency: New Drywall Building Material Can Cut Buildings' Energy Consumption by 40%
Science Daily

K. Darkwa, 07/01/2005. Dynamics of energy storage in phase change drywall systems
International Journal of Energy Research , 29

Alicia Oliver, 04/26/2012. Morphological Study of Gypsum Boards with PCM through Scanning Electron Microscopy
American Society of Civil Engineers

Ben Coxworth, 08/02/2012. Phase-change drywall boards store and release heat to save power
gizmag

Jan Kosny, 01/01/2013. Cost Analysis of Simple Phase Change Material-Enhanced Building Envelopes in Southern U.S. Climates
U.S. DOE Building Technologies Program

Rank & Scores

Phase-change Materials

2014 Residential Building TAG (#10)

Technical Advisory Group: 2014 Residential Building TAG (#10)
TAG Ranking:
Average TAG Rating: 2.76 out of 5
TAG Ranking Date: 04/10/2014
TAG Rating Commentary:

I do have some confusion in the detailed page. It says low incremental cost but that cost is still a barrier. That makes it sound like a reasonable incentive could have an impact on adoption. Also good addition to a new construction package. Maybe even a retrofit(?).
Has potential, but seems as though it is highly dependent on other variables such as HVAC utilization.
Not clear how this is significantly more valuable than double-layers sheetrock or other thermal mass increasing designs.

2014 Commercial Building TAG (#9)

Technical Advisory Group: 2014 Commercial Building TAG (#9)
TAG Ranking: 12 out of 44 Technologies (2014 Commercial TAG strategies ranked separately)
Average TAG Rating: 3 out of 5
TAG Ranking Date: 03/17/2014
TAG Rating Commentary:

Concept is potentially useful for energy management - in both cooling and heating seasons. The devil is in the details- what materials, what properties, what application, how is the HVAC managed.
There is evidence in multiple efforts that we have been involved with that there is potential with this technology.
Incremental costs are now quite low and it can be bundled with insulation and installed all at once, which offers key cost advantages.
A fantastic regional fit given our climate, and one without the necessary aesthetic burden of some of the other material solutions. This is a proven technology with a wide variety of applications.
Cost appears to still be a barrier; may be a more applicable technology to thermal energy storage