Electrochromic Windows

Summary

Electrochromic Windows

Window Glazing: Electrochromic vs. Conventional

Windows that can modulate heat gain, light transmittance, and glare from the sun and can be controlled locally or by an energy management system.

Synopsis:

Windows with electrochromatic tinting capability are currently offered by Sage Electrochromics and Soladigm. Electrochromic windows can be controlled to modulate both heat, light, and glare from the sun while preserving views. These windows can be controlled locally or interconnected into a building automation system.

Electrochromic window glass is fabricated into industry standard units that fit into a variety of window, skylight, and curtain wall frame sizes. These smart windows negate the need for traditional sun control building add-ons such as shades, blinds, or overhangs. Electrochromic windows can be controlled in a number of ways: two tint levels (fully tinted and fully clear); four tint levels (fully tinted, fully clear, and two intermediate levels); configured to maintain a constant light level, or automatic control by the building energy management system based upon time of day or occupancy sensor readings.

The Sage webiste cites a U.S. Department of Energy study that estimates that electronically tintable windows systems are capable of providing up to:
---a 20% savings in operating costs
---a 24% reduction in peak demand, and
---a 25% decrease in the size (capacity) of HVAC systems.

Electrochromic windows are ideal for offices, museums, libraries, art galleries, health care facilities, schools and universities, religious buildings, and high-tech or image buildings. Electrochromic windows are installed at the Health Sciences Complex at Chemketa Community College in Salem, OR.

The technology did not develop a market when available at $100 per square foot. Prices in mid-2013 are as low as $30 per square foot of glass, and are expected to continue dropping at 5-10% annually. Electrochromic windows provide additional benefits in applications where glare and heat gain are periodically big issues. View Inc claims that the savings in HVAC system sizing and elimination of blinds etc. can pay the incremental cost, especially for institutional owner occupants such as healthcare, education and government with long payback horizons.

Energy Savings: 19%

Energy Savings Rating: Limited Assessment 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

Electrochromic Windows

Window Glazing: Electrochromic vs. Conventional

Windows that can modulate heat gain, light transmittance, and glare from the sun and can be controlled locally or by an energy management system.

Item ID: 262

Sector: Commercial

Energy System: Building Envelope--Windows & Skylights

Technical Advisory Group: 2014 Commercial Building TAG (#9)
Average TAG Rating: 2.7 out of 5
TAG Ranking Date: 03/17/2014
TAG Rating Commentary:

This is a game changing technology if the right product can be brought to market at the right price point and be fully integrated into building EMS. There are numerous technical and market challenges looming that have slowed market penetration but the two current market leaders have products with good properties- engagement in the ET program could help with barriers. We have lots of technical experience with the integration and field testing challenges here
I think the photograph shows thermo-chromic glazing. I am not familiar with this technology in the form of a retrofit coating. If it is the same coating that is used in electro-chromic glazing, I assume that they have the same performance. Electro-chromic glazings has been around for quite sometime. I am not sure how ready they are for the market in terms of cost and operational capabilities. New versions are expected that improve on operational capabilities and will hopefully be at lower cost. I do not know about the cost of the retrofit film.
Cost is a significant barrier with this technology. My impression is that without significant cost reduction, broad uptake may be a challenge to implementation.
Better than 263. With the prices dropping these are a very attractive energy efficiency investment. However, still very few buildings have Building Automation Systems that can utilize these to the full extent.

Synopsis:

Baseline Example:

Baseline Description: South- and west-facing commercial building space with conventional glazing
Baseline Energy Use: 10.5 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).

Since this technology can be applied to many types of commercial buildings, a baseline heating and cooling energy use of 10.5 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: 19%
Energy Savings Reliability: 3 - Limited Assessment

Comments:

Annual boiler gas consumption was reduced by 19% after installation of electrochromic windows in a building in Colorado (mocked up in Window 6 and EnergyPlus). Annual HVAC energy use due to cooling equipment similarly was reduced by 22% in the modeling study. The building modeled had clear, single-pane, wood-framed windows.

Energy Use of Emerging Technology:

8.5 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: 11,080,263
Comments:

This technology could technically be used for virtually any commercial building (preferably with electric space heat to maximize electrical energy savings) except for warehouses and unconditioned space (84.7% x 27.1%, Table C-GB13) . However, window installation will be most appropriate for just the south-and west-facing windows in the Northwest. The numbers for total commercial building space 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), minus warehouse space, multiplied times the percentage of commercial space that is conditioned based on the 2009 CBSA, times our rough estimate of 50% of applicable space, which would count south-and west-facing perimeter zones plus half the interior space associated with those zones.

This number is further tempered as electrochromic windows can reduce only perimeter zone heating, ventilation, air conditioning, and lighting energy use. The savings is decreased due to buildings already deploying tinted and/or Low-E windows and due to buildings that use occupancy sensors and daylighting controls. The 2009 "Northwest Commercial Building Stock Assessment" indicates that 27.9% of commercial buildings have single layers of glazing. In addition, 53% of the windows are tinted. To reflect these constraints, the energy savings will be further reduced by 25% x 27.9% x 47% to yield an eligible square footage of 11,080,263 sf.

	Total Floor space	-s.f. Warehouse	non-Warehouse	% Conditioned, Electrically Heated	% Applicable	Applicable Space
Source	(NEEA, 2014)	(NEEA, 2009 App C)	(NEEA, 2009 App C)	(NEEA, 2009 App D, Table D-EA1)	WSU EP
Values:	3,118,000,000	173,000,000	2,945,000,000	84.7% x 27.1%	50%	337,993,233

Regional Technical Potential:
0.02 TWh per year
3 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:

A cost increase of $37/sf-glass was assumed for an electrochromic window and controls in contrast to a Low-E window given a mature market.

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:

Joe Verrengia, 01/22/2010. Smart Windows: Energy Efficiency with a View
National Renewable Energy Laboratory

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

Eric Wesoff, 06/18/2013. Corning Leads $60M VC Round for Windows With Tint Control
Greentech Media

NREL, 10/02/2013. Materials Science: Electrochromic Windows
National Renewable Energy Laboratory

U.S. DOE, 04/05/2011. Making Smart Windows Smarter
U.S. Department of Energy

LBL, 01/01/2014. Smart Windows
Lawrence Berkeley National Laboratory

Rong-Hua Ma, 12/30/2011. BIPV-Powered Smart Windows Utilizing Photovoltaic and Electrochromic Devices
Multidisciplinary Digital Publishing Institute (MDPI)

Dariush Arasteh, 05/22/2006. Zero Energy Windows
Lawrence Berkeley National Laboratory

LBL, 01/01/2006. Advancement of Electrochromic Windows
Lawrence Berkeley National Laboratory

University of Minnesota , 01/01/2011. Windows for high-performance commercial buildings
University of Minnesota

Katherine Bourzac, 07/19/2012. Smart Glass Made In One Step
Chemical & Engineering News

Lauren Sommer, 05/25/2012. Energy-Saving Windows Get Smarter
QUEST Northern California

Ucilia Wang, 08/13/2010. Making Smart Windows that Are Also Cheap
MIT Technology Review

Eleanor Lee, 12/01/2014. A Pilot Demonstration of Electrochromic and Thermochromic Windows in the Denver Federal Center, Building 41, Denver, Colorado
Lawrence Berkeley National Laboratory

Rank & Scores

Electrochromic Windows

2014 Commercial Building TAG (#9)

Technical Advisory Group: 2014 Commercial Building TAG (#9)
TAG Ranking: 19 out of 44 Technologies (2014 Commercial TAG strategies ranked separately)
Average TAG Rating: 2.7 out of 5
TAG Ranking Date: 03/17/2014
TAG Rating Commentary:

This is a game changing technology if the right product can be brought to market at the right price point and be fully integrated into building EMS. There are numerous technical and market challenges looming that have slowed market penetration but the two current market leaders have products with good properties- engagement in the ET program could help with barriers. We have lots of technical experience with the integration and field testing challenges here
I think the photograph shows thermo-chromic glazing. I am not familiar with this technology in the form of a retrofit coating. If it is the same coating that is used in electro-chromic glazing, I assume that they have the same performance. Electro-chromic glazings has been around for quite sometime. I am not sure how ready they are for the market in terms of cost and operational capabilities. New versions are expected that improve on operational capabilities and will hopefully be at lower cost. I do not know about the cost of the retrofit film.
Cost is a significant barrier with this technology. My impression is that without significant cost reduction, broad uptake may be a challenge to implementation.
Better than 263. With the prices dropping these are a very attractive energy efficiency investment. However, still very few buildings have Building Automation Systems that can utilize these to the full extent.