Electrochromic Auto-Darkening Windows for Buildings for Energy Conservation Based on Unique Conducting Polymers and Already Demonstrated in Sunglasses
Per DOE, other sources, residential, commercial buildings account for >40% of total US energy demand, >70% total US electricity use, costing >$430 billion/year [1]. Per DOE, “approximately 35% of this $430B/year consumption can be attributed to losses through the building envelope, via heat transfer” [1]. If auto-darkening windows were available, energy for cooling could be greatly reduced, resulting in annual US savings of ~$30.1B/year, ~50m tonnes CO2 [1]. Drawbacks of extant electrochromic window technologies (e.g. by Sage Glass, View, Heliotrope, others): (i) Price $50 to $300/ft2 (cf. our price ~$5/ft2, USA production). (ii) OEM, requiring expensive replacement of existing windows (vs. ours, retrofittable). (iii) Poor light/dark (L/D) contrast, typically 22% to 60% (Delta 38%). (iv) Poor long-term stability. Due to this, the commercial market for electrochromic windows has been limited to date, with few buildings outfitted. Photochromics, LCD-based electrochromics, other CP-electrochromics are not really applicable to building windows. Now in ongoing/prior work, we have developed, patented (>15 patents) novel, inexpensive, auto-darkening electrochromics based on unique dual-polymer electrochromic Conducting Polymers [2,3]. Our sister company, AshChromics, is commercially launching electrochromic sunglasses, motorcycle visor inserts, ski goggles, end-2019. Our technology’s features: (i) Thin (<0.4 mm), flexible durable, naturally UV-blocking. (ii) Desirable color change (transparent to dark-blue-black, other colors possible), excellent optical memory. (iii) High cyclability: >1M L/D (light/dark) cycles; shelf life >3 years. (iv) High L/D contrast, 1% to 70% and all values in between (Delta >65%). (v) Unique applied-voltage algorithm on an inexpensive (<$5) Microcontroller, drastically reduces switching time (<2s L→D, ~instantaneous D→L). (vi) Fully automated, photosensor-based control per ambient light; manual override available. (vii) Low power,15 µW/cm2, +/-3.0 VDC. (vii) Semi-automated manufacture demonstrated. (viii) Manufacturing initiated (2019, northern NJ). (ix) ALL above features are readily transferred to building windows. Key for building-windows application is transitioning excellent small-area electrochromic function (sunglasses) to larger areas (building windows); this involves use of conductive gridlines, somewhat like those of automobile rear-window defrosters. In Phase I, firstly, methods proposed in our original Phase I proposal were implemented, producing well-functioning large-area (1m2) electrochromic windows. Secondly, an innovation not in our Phase I proposal was implemented that significantly reduced cost (to ~$30/ft2), successfully demonstrated at the DOE PI Meeting (12/2018). Thirdly, two additional innovations also not in our original proposal were implemented that dramatically reduced cost (to ~$5/ft2); large-area windows with these were demonstrated at DOE BTO Meeting (04/2019). Design for semi-automated manufacturing at ~1000 m2/month was finalized. Commercialization tie-ups with a major US architectural windows company and others were established; VC interest was initiated. All original Phase I Objectives were significantly exceeded. In Phase II: (1) Three new Phase I innovations will be optimized. (2) Electrochromic windows of standard window sizes will be fabricated, characterized, optimized. (3) Both retrofit, OEM models will be demonstrated. (4) Detailed costing, manufacturing design will be completed. (5) Commercialization tie-ups with existing partners will be finalized. (6) Marketing will be initiated with firm currently doing our sunglasses marketing. (7) Tie-ups will be initiated with the VCs we are currently working with.
- Research Organization:
- Ashwin-Ushas Corporation
- Sponsoring Organization:
- USDOE
- Contributing Organization:
- Ashwin-Ushas Corporation
- DOE Contract Number:
- SC0018868
- OSTI ID:
- 1508155
- Type / Phase:
- SBIR (Phase I)
- Report Number(s):
- E3_PhI_FR_b
- Country of Publication:
- United States
- Language:
- English
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