Cost-Benefit Analysis of Smart Glass

Introduction

This is intended to be a quick ‘back-of-the-envelope’ estimation of the costs of various types of smartglass, stacked against their benefits. Our article is built on top of in-depth cost-benefit analyses such as:-

• this year-long study by the University of Washington confirming energy savings of up to 17%, roughly USD 28,000 a year, when a waterfront building in Seattle was installed with View electrochromic smart glass
• a multi-technology study by Gibbs College of Architecture at University of Oklahoma, identifying the most efficient smart window types according to 31 different climate zones (encompassing tropical, arid, temperate, continental and polar climates)
• a cost-benefit analysis of PDLC privacy glass, as applied to offices (mostly meeting rooms and conference rooms)

Payback Period

Just as with photovoltaic panels, there is a Payback Period with smartglass. However, it is notoriously difficult to calculate since there are multiple (very different) smartglass technologies available on the market. NB: We should remember that smartglass is a product family, much like wood, concrete or metal. Added to this are the variety of configurable elements (such as low-e coatings and PVB laminations) and the insulation of the window itself (double, triple or quadruple glazed), which affects the heat gain and the subsequent air conditioning costs. Just as each business has a different operational cost structure, the payback period of any investment in smartglass would also naturally be unique to each business. Having said that, by simply looking at the core technologies, we can estimate energy savings, soft benefits such as productivity and company morale, as well as the impact on environmental sustainability. Let’s dive in.

Background

Smartglass World, through our parent company, ArtRatio, has been manufacturing smartglass-based end-products since 2009 for clients in the art & luxury retail sectors. Below you can see one of our installations of SPD smartglass display vitrines at an exhibition of patrimonial jewellery for the French luxury house, Van Cleef & Arpels. This exhibition took place in Shanghai and Riyadh in 2022 and 2023.

Wall-embedded SPD smartglass display cases, designed and built by ArtRatio (our parent company), housing patrimonial jewellery from 1906 to present day. Image courtesy of Van Cleef & Arpels.

So you can see that we have experience in:

• designing and modelling smartglass solutions (electrical, optical and mechanical)
• specifying the smartglass ‘stackup’ (i.e. layers of materials) prior to purchase
• building steel and wooden frames for smartglass (incl. door mechanisms, locks and seals)
• delivering and installing complete display systems worldwide
• integrating the smartglass hardware with IoT sensors, operating systems and cloud-based data visualisation software
• explaining the benefits of the smartglass solution to customers and
• training users to maximise the benefits of smartglass for institutions, companies and private customers.

You can find more on the ArtRatio Installations page.

General Comments

For this article, we are going to look at a 1 square metre, single-pane, smartglass panel using various smartglass technologies, intended to be installed either on a building facade or in the building interior. We will compare various types of smartglass technology and analyse their benefits vs their costs. Some general comments:-

• With any smartglass technology capable of rejecting ultraviolet (UV) solar radiation, we can expect benefits that include: reduced UV exposure damage on retail inventories, hotel furnishings, artworks and manufactured goods such as footwear or pharmaceutical products, protecting their condition and thus market value;
• With any technology capable of rejecting infrared (IR) solar radiation, we can expect benefits that include: reduced air conditioning costs, improved comfort for employees, visitors and customers, and a subsequent improvement in morale and productivity;
• With technologies that can dynamically block or (diffusely) refract visible light, we can expect to see benefits that include better security, reduced material degradation from light exposure and enhanced privacy.

Let’s start with the technology we have most experience with:-

SPD SmartGlass

SPD-SmartGlass panels in the roof of McEwan Hall, Edinburgh University (courtesy of Smart Glass International Ltd). Image copyright: Don Munro Photography

SPD-SmartGlass is activated by an electrical voltage (typically 60-110 Vac), changing from opaque to 50% transmittance within 1-3 seconds, and giving colour rendering (Ra) of 95 when activated.

Specification:

• 13.5mm thick
• EN 356 (P4A) security rated
• Single pane glass (no internal insulation)
• Low-iron glass (reduces green tint due to iron oxide)
• 90 micron thick internal SPD layer embedded in PET film
• PVB lamination for UV-rejection and sound control

Costs:

• Approx. EUR 3500-4500 per square metre for the above specification
• Costs for mains voltage cabling which needs to be routed in the enclosure for each smartglass panel
• Costs of electrical safety components such as surge suppressors and isolating transformers
• Additional costs in electrical installation by a qualified professional and for lifetime maintenance
• Operational costs since SPD smartglass needs to be activated to become transparent, and consumes about 5-7W power the whole time the smartglass is on
• Strong blue hue when glass is switched off, leading to increased risk of erroneous medical diagnoses if used in healthcare facilities (with potential insurance or legal costs)
• Costs of activation mechanisms, such as push buttons, sensors or connection to the building management system

Benefits:

• Allows compliance with green building standards, such as LEED, BREEAM and VERDE regarding sustainable daylighting and energy-efficiency
• Improves health, productivity and comfort for building users
• Allows the building to dynamically adapt to weather conditions, both during the day and throughout the year
• Eliminates blinds, shades and motorised elements that block daylight coming into a building and the view looking out of the building
• Eliminates UV almost entirely, reducing colour fading and material degradation on retail inventories, artworks and furnishings in homes, hotels and businesses
• Reduces IR (heat gain) by half, stabilising temperature / relative humidity cycles in museums, art galleries and private art collections, which can affect their insurable value
• The 50% reduction in heat gain can reduce air conditioning costs substantially
• Reduces light exposure damage on retail inventories, food / beverage and pharmaceutical products on display in highly-lit retail areas, protecting their market value. This does depend on the ‘duty cycle’ though (what percentage of time the glass is activated)
• Important security benefit for valuable items on display where items can be placed “out-of-sight, out-of-mind” and on-demand just by switching off the smartglass (usually done automatically by a proximity sensor), contributing to reduced insurance premiums thanks to these preemptive measures
• Excellent visibility in the transparent state thanks to the high colour rendering, with no added colouration apportioned by the glass itself, which is especially important for retail, arts and cultural sectors

Issues:

• Some supply chain issues recently in sourcing this product

Electrochromic Smartglass

Mohamed Bin Rashid Library, Dubai. Image credits: Sage Electrochromics

Electrochromic smartglass is activated by an electrical voltage, typically 3-5Vdc, changing from opaque (when off) to transparent within 2-15 minutes, with a power consumption of about 1W per square metre when changing tint (and no power consumption at all other times)

Specification:

• 13.5mm thick glass
• EN 356 (P4A) security rated glass
• Single pane
• Low-iron (reduces green tint due to iron oxide)
• PVB lamination for UV and sound-rejection

Costs:

• €1500-€2500 per square metre, approx.
• Minimal costs in cabling since this is an Extra Low Voltage, and could be driven directly by a photovoltaic panel, either on the window or the nearby building wall
• If the photovoltaic panels are on the roof, then cabling costs will of course need to be budgeted for
• Costs of activation mechanisms, such as push buttons, sensors or a building management system

Benefits:

• Allows compliance with green building standards, such as LEED, BREEAM and VERDE regarding sustainable daylighting and energy-efficiency
• Allows the building to dynamically adapt to weather conditions, both during the day and throughout the year
• Eliminates blinds, shades and motorised elements that block daylight coming into a building and the view looking out of the building
• Improves health, productivity and comfort for building users
• Good contrast between opaque (typ. 15% transmittance) and transparent (typ. 65% transmittance)
• Power consumption typ. 1 W/m2 when changing tint, and 0 W/m2 at standby
• Eliminates UV, reducing colour fading and material degradation
• Reduces IR (heat gain) by up to 60%, stabilising temperature / relative humidity cycles

Issues:

• Switching times in the minutes, not seconds (which can actually be advantageous for a building as it does not distract wildlife and road traffic)

PDLC Smartglass

PDLC (polymer-dispersed liquid crystal) smartglass is activated by an alternating (AC) electrical voltage, changing from translucent (when off) to transparent within 1-3 seconds, with haze figures down to 3% and power consumption of about 5-7W per square metre. There are also PDLC products available on the market that have a default transparent state when off.

PDLC smart film installation (UK). Credits: Intelligent Glass, MATT Architecture and Will Pryce Photography

Specification:

• 13.5mm thick glass
• EN 356 (P4A) security rated
• Single pane glass (no internal insulation)
• Low-iron (reduces green tint due to iron oxide)
• PVB lamination for UV-rejection and sound control

Costs:

• €250 – €1500 per square metre, approx.
• Mains cabling needs to be routed in the enclosure and costed for each smartglass panel
• Costs of electrical safety components such as surge suppressors and isolating transformers
• Additional costs in electrical installation by a qualified professional and for lifetime maintenance
• Operational costs since PDLC smartglass needs to be activated to become transparent, and consumes about 5-7W power the whole time the smartglass is on
• Costs of activation mechanism, such as push buttons, sensors or building management system

Benefits:

• Improves health, productivity and comfort for building users
• Eliminates UV almost entirely, reducing colour fading and material degradation on retail inventories, artworks and furnishings in homes, hotels and businesses
• Reduces IR (heat gain) by up to 80%, stabilising temperature / relative humidity cycles in museums, art galleries and private art collections, which can affect their insurable value
• The reduction in heat gain can reduce air conditioning costs substantially
• Since the transmittance of PDLC smartglass varies between 60%-80% (not like SPD smartglass), there is only a slight reduction in light exposure damage on retail inventories, food / beverage and pharmaceutical products on display in highly-lit retail areas
• Important security benefit for valuable items on display where items can be placed “out-of-sight, out-of-mind” and on-demand just by switching off the PDLC smartglass (usually done automatically by a proximity sensor), contributing to reduced insurance premiums thanks to these preemptive measures
• Excellent visibility in the transparent state thanks to the low haze, especially important for retail, arts and cultural sectors

Issues:

• Some suppliers inaccurately refer to this as ‘electrochromic glass’, probably in order to increase chances of getting selected by customers looking to comply with the US Dynamic Glass Act (which erroneously refers to all electrically-powered smartglass as ‘electrochromic glass’)
• Huge variety in supplier and product quality, as this is the most prevalent technology in the marketplace at the moment

Thermochromic Smartglass

Thermochromic test samples, image courtesy of Vario Glass

Thermochromic smartglass is activated by changes in temperature, changing from transparent (when below the threshold temperature, typically 25ºC) to opaque within a few minutes. Thermochromic glass reflects infrared, even at lower temperatures, despite being transparent to visible light.

Specification:

• 13.5mm thick glass
• EN 356 (P4A) security rated glass
• Single pane PVB lamination for UV and sound-rejection

Cost:

• €500-€1000 per square metre, approx.

Benefits:

• Allows compliance with green building standards, such as LEED, BREEAM and VERDE regarding sustainable daylighting and energy-efficiency
• Improves health, productivity and comfort for building users
• No cabling costs at all, since this is not driven electrically and also needs no connection to activate it (it is activated by an increase in its surface temperature due to the sun)
• Eliminates UV thanks to internal PVB lamination, reducing colour fading of furnishings and artworks
• Reduces IR (heat gain) by 60%, stabilising temperature / relative humidity cycles
• Low haze, excellent visibility

Issues:

• Colour change not visible until glass surface temperature reaches 50-60ºC
• Only moderate contrast in some thermochromic technologies between transmittance levels (75% transmittance at 20ºC to 60% transmittance at 80ºC)

Photochromic Smart Film

Photochromic smart film is activated by changes in UV and visible light, changing from transparent to opaque within a few minutes of light exposure.

Photochromic film adapts to changes in sunlight

Specification:

• 2mm thick film, applied to inside of glass

Cost:

• €50-€100 per square metre, approx.
• Installation costs of applying the film to window interiors

Benefits:

• Allows compliance with green building standards, such as LEED, BREEAM and VERDE regarding sustainable daylighting and energy-efficiency
• Improves health, productivity and comfort for building users
• No cabling costs, since it is not driven electrically
• Reduces IR (heat gain), stabilising temperature / relative humidity cycles
• Fairly quick to change state (a few minutes)
• Low haze, excellent visibility

Issues:

• Not available as a laminated glass product (as far as we know)

Customised Cost-Benefit Analysis

If you are looking for a customised cost-benefit analysis, including an analysis of the opportunity costs (i.e investing your money in another solution that is not smartglass), then consider hiring us as your smartglass consultants. We have broad experience with smartglass since 2009, and we have a deep understanding of the science behind them, as you can see from our Learning portal page.

Smartglass Samples

If you are looking for samples of various types of smartglass and smart film, then rather than going to multiple suppliers, just buy direct from our Samples page. We have cost-effective prices, stock on-hand and we offer immediate delivery (with several cost options) via our global logistics provider, DHL Express.

Smartglass MarketPlace

And if you want to take a DIY (Do It Yourself) approach to costing smartglass, we have also contemplated this as an option in our marketplace with our parameterised search. This allows you to search for smartglass suppliers by product type and product attributes, such as minimum transmittance, power consumption or voltage rating, whittling down the hundreds of supplier products in our database to just a few in a matter of minutes. You can then post a request which will be emailed directly to your chosen suppliers, whereupon they will contact you directly. A bit like a digital bulletin board.

Conclusions

Each technology has its own costs (direct and indirect), as well as benefits and issues, so no surprises there. The thing to watch out for is the quality of the supply chain, since some suppliers are not accurate about what they are supplying (with some even confusing the names of the very technology they are selling). One example is the confusion between ‘opaque’ vs ‘translucent’, and the incorrect usage of the term ‘electrochromic’. The recent macroeconomic upheaval has resulted in price volatility, supply chain instability and is compounded by variable market demand. This is despite fiscal tax breaks and government incentives, such as the US Dynamic Glass Act, the EU Net Zero Industry Act and the UK 2025 Future Homes Standard. So, challenging (but also potentially exciting times) ahead for the smartglass sector. Chin up!