Cost-effective dynamic daylighting for existing buildings
Montage showing IntelliBlind, IntelliBlind mounted on its host blind, and an urban skyline

Target Application: Retrofit Daylighting in Office Buildings

The IntelliBlinds™ Model D can enhance comfort, convenience, and energy efficiency in any building with windows, but its development was focused on a specific high-payoff application: retrofit daylighting in office buildings.

Using daylight-harvesting lighting controls in every U.S. office building could slash the lighting bill by $400 million per year, but that potential remains virtually untapped. A major reason is that most office windows must be shaded to control glare. With manually adjustable shades, the windows are over-shaded most of the time, halving the average savings and doubling the payback period. That's a serious problem, because the market is notoriously sensitive to payback period. And conventional automated shading technology is so expensive that adding it to a daylight-harvesting installation lengthens the payback period even further.

But now, with the IntelliBlinds™ Model D, any ordinary miniblind can be instantly converted into a cost-effective Dynamic Daylight Control (DDC) system. By automatically adjusting the shading to maximize glare-free natural illumination, DDC more than doubles the average energy savings from daylight harvesting while eliminating uncertainties due to dependence on manual shading adjustments. And because IntelliBlinds™ costs less than all but the least expensive daylight-harvesting lighting controls, it also shortens the payback period.

But while a short payback period is the key prerequisite for success in the energy efficient retrofit market, it's not the only one. IntelliBlinds™ was developed from the outset to also be easy to manufacture and distribute; to be interoperable with all daylight-harvesting lighting controls; to complement (rather than compete with) successful products already on the market, and to be perceived as an amenity (rather than strictly as an energy saving device) by building occupants.

Based on shortened payback period alone, standard market penetration models show that IntelliBlinds™ will increase the ultimate installed base and aggregate sales of daylight harvesting lighting controls by 220 million square feet and $120M, respectively, in the USA alone. IntelliBlinds™ will increase the annual savings from daylight harvesting by 560 million kWh and $80M, in turn reducing annual C02 emissions by 400,000 metric tons. And ultimate aggregate sales of the IntelliBlinds™ Model D itself will reach $340M. Moreover, these projections are for retrofit sales for office buildings only, and do not consider other market segments or the likely growth in non-residential floor area.

Daylighting for Office Buildings

Simply turning off or dimming lamps to take advantage of available daylight can save 75% of the electricity used in artificial lighting. And daylight-harvesting lighting controls that do that automatically have been available for decades.

While virtually every windowed building is a potential candidate for daylight harvesting, it's most cost-effective in interior spaces that require plenty of illumination, receive plenty of daylight from windows or skylights, and are occupied mostly during daytime. Office buildings contain more floor area that meets all of those criteria than any other non-residential or residential building type—about 4.4 billion square feet in the U.S. alone. That makes office buildings the prime target for energy savings via daylight harvesting.

Aerial view of Manhattan showing hundreds of office buildings under a sunny sky
Chart 1: As Virtual "Glass Boxes" Occupied Mostly in Daytime, Office Buildings are Ideal Candidates for Daylight Harvesting

The Challenge: Over-Shaded Windows

As is the case with other building types, the bulk of the potential daylit area in office buildings is sidelit via eye-level view windows. View windows must be shaded to control heat and glare, and are typically equipped with adjustable window coverings for that purpose.

Because office activities are relatively sensitive to excessive brightness and glare, office windows are usually more heavily shaded than windows in other buildings. For example, the following chart shows the window shading on the sunny facades of both office and mixed-use buildings in a high-density urban complex:

Ground-level view of urban complex, showing office-building average shading of 60 percent and mixed-use average shading of 15 percent
Chart 2: Office-Building Windows are Shaded More Heavily than Windows of Other Non-Residential Buildings

In Chart 2, all of the buildings are receiving strong indirect sunlight. As a result, the occupants of the office buildings have been forced to lower the shades to control glare—but the windows of the other buildings remain relatively unshaded.

So what happens to the office-building shading when the daylight level drops? Mostly nothing, because office occupants are far less likely to open the shades when there's too little daylight than to close the shades when there's too much.

For example, the following shows a time-lapse pan of the same office building of Chart 2, but at dusk instead of daytime:

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Movie 1: Office Windows Remain Shaded Even at Dusk

Despite the fact that there's zero risk of daylight-induced glare, only one shade was opened during the time-lapse interval, and the average shading remains at about 60%.

This example illustrates what numerous studies* have shown: while adjustable window coverings are easy to operate, the occupants of office buildings rarely adjust them. Instead, they set the window shading to block glare under worst-case conditions, and then keep that setting for days or even weeks.

This chronic over-shading reduces the average level of useful daylight by about two-thirds, which more than doubles the median payback period for investments in daylight-harvesting lighting controls. Further, because the savings depend on occupants' willingness to make manual shading adjustments, the long-term savings can't be reliably predicted for any given installation.

Those are serious impediments to mainstream adoption of daylight harvesting, because buyers of non-residential energy saving products are notoriously risk-averse and extremely sensitive to payback period. The percentage of sidelit floor area in U.S. office buildings equipped for daylight harvesting has remained at less than 2% for over a decade—while other technologies that save less energy have rapidly penetrated the market.

*Window shading usage in office buildings has been the subject of many research studies, many of which are summarized in The Need for Dynamic Daylight Control.

What's Been Missing: Cost-Effective Dynamic Daylight Control (DDC)

In the late 1990's, researchers at Lawrence Berkeley National Laboratory (LBNL) demonstrated the solution to the problem of over-shaded windows in daylighting applications: Dynamic Daylight Control (DDC) via automated window shading.

Through simulations as well as long-term testing of prototype systems, LBNL demonstrated that using DDC in conjunction with daylight harvesting can double the energy savings, with no risk of visual or thermal discomfort. Similar dynamic daylighting systems are now commercially available and have been installed in a few high-profile buildings in the USA.

Unfortunately, conventional DDC technology is complex, difficult to distribute, and costs much more than daylight-harvesting lighting technology. Thus, while adding conventional DDC technology to a daylighting installation reduces the uncertainties and doubles the savings, it also significantly lengthens the payback period, making conventional DDC a non-starter for mainstream use.

So, despite the passage of almost two decades since LBNL's groundbreaking demonstration, the market penetration of dynamic daylighting remains negligible—and the enormous potential of daylight harvesting remains mostly untapped.

The Need for Dynamic Daylight Control provides more information on why DDC is crucial for effective daylight harvesting in sidelit spaces.

IntelliBlinds™ Unlocks Daylighting's Full Potential

Now, with IntelliBlinds™, DDC is finally practical for mainstream daylighting applications. In the same way that a daylight-harvesting lighting control converts an existing luminaire into a daylight-harvesting lighting system, the IntelliBlinds™ Model D quickly and inexpensively converts any wand-actuated miniblind into a state-of-the-art DDC system.

When IntelliBlinds™ and its host blind are installed near a daylight-harvesting lighting system, the result is a high-performance, cost-effective dynamic daylighting system. IntelliBlinds™ automatically adjusts the blind to maintain the desired level of glare-free daylight, while the lighting control harvests that daylight by dimming or switching the lamps to maintain the desired total illumination.

IntelliBlind regulates the daylight level, while the lighting control regulates the total illumination
Chart 3: Dynamic Daylighting with IntelliBlinds™

Works with all Daylight-Harvesting Lighting Controls

Unlike conventional DDC technology, the IntelliBlinds™ Model D doesn't have to be integrated with the daylight-harvesting lighting system. Instead, IntelliBlinds™ operates autonomously, regulating the daylight level while ignoring changes in the dimming level of the lamps. No connections of any kind are required between IntelliBlinds™ and the lighting system, and the lighting system doesn't have to be modified in any way.

In addition to reducing hardware and installation costs, this ensures that IntelliBlinds™ is compatible with all daylight-harvesting lighting systems, regardless of design:

  • It works with the most complex DALI-based multi-luminaire systems, as well as the simplest self-contained, single-luminaire controls.
  • It works with Switching-Only (SO), Dimming-Only (DO) and Dimming-and-Switching (D&S) controls.
  • It works with open-loop and well as closed-loop control protocols.
  • It works with LED as well as fluorescent lamps.
Because of its simplicity and low cost, the IntelliBlinds™ Model D is an ideal complement to today's stand-alone (versus networked) lighting controls, such as those discussed in Daylight Harvesting Lighting Controls. The combination of IntelliBlinds™ and such controls yields a highly cost-effective dynamic daylighting system that's free from the distribution challenges associated with complex integrated systems.

Slashes Cost of Dynamic Daylighting by Almost Half, Yet Saves Even More Energy

In addition to eliminating the need for connections to the lighting system, the IntelliBlinds™ Model D incorporates a half-dozen major innovations to further slash the costs of dynamic daylighting. The following chart provides a breakdown of the installed costs per window of IntelliBlinds™ and a dynamic daylighting system using conventional DDC technology:

IntelliBlind's innovative technology slashes DDC's major cost drivers, reducing DDC cost by two-thirds and overall dynamic daylighting cost by almost half
Chart 4: Median Price of Dynamic Daylighting in Typical Retrofits
For conservatism, the "conventional DDC" costs of Chart 4 aren't based on off-the-shelf systems (which are substantially more expensive). Rather, they're based on a hypothetical reference system using conventional technology, but engineered for minimum cost in volume production. Conventional Technology provides more information on conventional DDC technology in general and the reference system in particular.

Yet, despite costing much less, IntelliBlinds™ actually saves more energy than conventional DDC systems. That's because its patented IntelliLux™ sensor is better than conventional sensors at sensing daylight as perceived by the building occupants, allowing IntelliBlinds™ to admit more useful daylight without risk of glare or excessive brightness. The result is about a one-third increase in the median projected kWh savings in U.S. office buildings:

When used with a dimming-and-switching lighting control, IntelliBlind saves about one-third more lighting energy than conventional DDC technology
Chart 5: Median Projected Energy Savings from Dynamic Daylighting with Dimming-and-Switching Lighting Control in Typical Retrofit

More than Doubles the Savings from Daylight Harvesting

Because daylight-harvesting lighting controls in sidelit areas are usually "daylight-starved", the additional glare-free daylight provided by IntelliBlinds™ is enough to dramatically boost the savings. The following charts show the median projected energy savings (Chart 6) and projected dollar savings (Chart 7) per square foot across office buildings in the USA, with and without IntelliBlinds™, for various daylight-harvesting configurations:

IntelliBlind doubles the energy savings from a dimming-only lighting control, almost triples the savings from dimming-and-switching controls, and multiplies the savings from switching-only controls by a factor of ten
Chart 6: Median Projected Energy Savings from Daylight Harvesting in Typical Retrofit
IntelliBlind doubles the dollar savings from a dimming-only lighting control, almost triples the savings from dimming-and-switching controls, and multiplies the savings from switching-only controls by a factor of ten
Chart 7: Median Projected Dollar Savings from Daylight Harvesting in Typical Retrofit

The increases are particularly striking for Switching-Only (SO) controls, because without DDC, there's rarely enough daylight in sidelit areas for the lamps to switch off. IntelliBlinds™ boosts the average daylight level so that the lamps stay off for a significant portion of the day, yielding substantial savings.

Shortens the Payback Period

In addition to costing much less than conventional DDC technology, the IntelliBlinds™ Model D also costs less than all but the least-expensive daylight-harvesting lighting controls. So IntelliBlinds™ doesn't just boost the energy savings from daylight-harvesting; unlike conventional DDC technology, it can also significantly shorten the payback period.

The following chart shows the projected payback periods for typical daylight-harvesting retrofit projects in U.S. office buildings, with and without IntelliBlinds™ and conventional DDC technology:

The impact of IntelliBlind on the daylight-harvesting payback period depends on the type of lighting control
Chart 8: Typical Retrofit Payback Periods for Daylight Harvesting

Conventional DDC is most cost-effective when it's used with a Dimming-and-Switching (D&S) control. But because it's so expensive, including conventional DDC in a D&S installation more than doubles the payback period. Even worse, the resulting paybacks are far longer than the 2–4 years typical of successful products.

With the IntelliBlinds™ Model D, on the other hand, the near-tripled energy savings don't come at the price of a longer payback period. On the contrary, IntelliBlinds™ significantly shortens the payback period for every configuration except the single-zone Dimming-Only (DO) control. The payback shortening is particularly striking for two of the most useful daylight harvesting configurations: single-zone Switching-Only (SO) and dual-zone Dimming-and-Switching (D&S):

  • SO controls are the simplest and least expensive form of daylight harvesting lighting control, but provide negligible savings in over-shaded sidelit areas because there's rarely enough daylight for the lamps to switch off. IntelliBlinds™ boosts the average daylight level so that the lamps stay off for a significant portion of the day, dramatically shortening the payback period.
  • D&S controls provide the greatest savings, but are also the most expensive form of daylight-harvesting lighting control. With over-shaded windows, there isn't enough daylight to fully exploit the D&S control's switching capability, so the added cost isn't offset by increased savings. IntelliBlinds™ boosts the average daylight level enough to fully exploit the switching capability, shortening the payback by 30–40%.

Without IntelliBlinds™, the payback period of D&S controls in sidelit areas is marginally too long to appeal to mainstream buyers--and SO controls are completely out of the question. IntelliBlinds™ shortens the paybacks of both D&S and single-zone SO controls enough to make them competitive with other successful energy saving technologies on the market.

The paybacks shown above assume typical utility rebates available across most of the U.S. If rebates were excluded from the analysis, the payback-shortening impact of IntelliBlinds™ would be much greater. That's because DDC technology currently benefits only from "custom" rebates, while daylight-harvesting lighting controls receive much more lucrative "prescriptive" rebates. When IntelliBlinds™ also qualifies for prescriptive rebates, the paybacks will be even shorter than shown above—and the payback-shortening effect of IntelliBlinds™ even greater.

Reduces Risk

The energy savings from daylight harvesting in sidelit areas are notoriously unpredictable, and are usually much less than the savings estimated using otherwise reliable methods. For example, a 2005 study found that daylight-harvesting lighting controls in sidelit spaces were providing only a fraction of the savings predicted by the DOE-2 building energy analysis program ("Sidelighting Photocontrols Field Study" 2005, page 8).

A major driver of this uncertainty is the variance in the settings of manually adjustable shading devices. This leads to a significant variance in the daylight harvesting payback periods even when all the other variables are accounted for. The following charts show this payback variance for several daylight harvesting configurations, with and without IntelliBlinds™ and conventional DDC:

IntelliBlind reduces both the median and the 75th percentile paybacks from daylight harvesting, the latter by a huge margin
Chart 9: Quartiles of Projected Payback Periods for Daylight Harvesting, Near Zone Only
IntelliBlind reduces both the median and the 75th percentile paybacks from daylight harvesting, the latter by a huge margin
Chart 10: Quartiles of Projected Payback Periods for Daylight Harvesting, Both Near and Far Zones

By tightening the payback distributions, the IntelliBlinds™ Model D dramatically reduces the risk associated with investments in daylight harvesting.

IntelliBlinds™ offers a user-adjustable daylight set-point, and it is possible for the user to select a set-point that still results in over-shading, thereby causing some residual shading-driven variance in the expected savings. However, our testing (as well as independent research) shows that people prefer daylight to artificial light—and prefer clear exterior views to shaded windows—when there is no risk of glare. Actual user-selected set-points during IntelliBlinds™ testing resulted in virtually no over-shading loss.

Appeals to Building Occupants as well as Owners/Operators

For building owners/operators—who actually sign off on investments in energy efficiency—a short, low-risk payback period is the most important product attribute. But no matter how short its payback period, an energy saving product won't succeed if it alienates the people who actually have to live with it: the building occupants.

That's not an issue for IntelliBlinds™. Our testing shows that, rather than alienating building occupants, IntelliBlinds™ is perceived as an amenity:

  • As many studies have shown, the occupants of non-residential buildings generally prefer a greater proportion of daylight to artificial light, as well as clearer outside view. By automatically keeping the blinds as open as possible without risk of glare, IntelliBlinds™ improves the subjective quality of the visual environment in both respects.
  • Unlike some energy saving technologies (e.g. computer-controlled thermostats that can't be locally adjusted), IntelliBlinds™ doesn't deprive occupants of any control over their environment. Rather, they—and not IntelliBlinds™—determine the shading settings and daylight set-point.
  • By providing users' preferred shading settings when DDC isn't engaged (such as automatically closing the blinds after dusk to maintain privacy), IntelliBlinds™ provides some of the same convenience benefits as conventional automated shading products. Some people are willing to pay hundreds of dollars per window to obtain those benefits in their own homes—and IntelliBlinds™ provides them in the workplace for free.

For a product like the IntelliBlinds™ Model D, pleasing building occupants isn't important just because it eliminates a potential reason not to install it in the first place. It's also important because it ensures that occupants won't try to bypass or sabotage it once it's installed, which is often what happens to energy saving devices that alienate the people who have to live or work with them.

Complements—Rather than Competes with—Established Products

The IntelliBlinds™ Model D competes with nothing else on the market. No other DDC technology is even remotely cost-effective for retrofit applications, so it won't face direct competition. And because it works with all daylight-harvesting lighting controls, there's no risk of incompatibilities (and therefore indirect competition) with the lighting controls carried by would-be distributors.

On the contrary, IntelliBlinds™ complements existing products because it provides a new way to save energy that can't be cost-effectively saved by any other means. Obviously, it works synergistically with daylight-harvesting lighting controls, but it also strengthens the value proposition for at least two other established products:

  • Because IntelliBlinds™ automatically adjusts its host blind to reduce loads on a building's HVAC system when the lamps are switched "off", it works synergistically with occupancy sensing light switches to provide an additional mechanism for saving energy.
  • Low-e window films and glazings save energy because they make daylight "cooler", reducing solar heating loads on the HVAC system. But the technology doesn't reduce visible light, so it doesn't eliminate the need for shading—and its benefit is reduced with over-shaded windows, because a closed blind reflects both heat and light back out the window. IntelliBlinds™ eliminates over-shading, so it increases the value of the "cooler" daylight produces by these products.

This synergy and absence of direct competition will facilitate distributor acceptance, helping to make the IntelliBlinds™ Model D a natural candidate for any comprehensive energy efficient retrofit project.

Broadens the Market for Daylight Harvesting

The IntelliBlinds™ Model D mitigates the two biggest impediments to widespread adoption of daylight-harvesting: excessive payback period and uncertainty in realized savings. The result will be a significant increase in the market penetration and aggregate sales of daylight-harvesting lighting controls, as well as an even more significant increase in the aggregate domestic savings from daylight harvesting. And sales of IntelliBlinds™, itself, will be substantial. The following table summarizes the results of a detailed analysis of these market impacts:

Table 1: Summary of IntelliBlinds™ Market Impact at Saturation
Increase in floor area equipped with daylight-harvesting lighting controls 220 million square feet
Increase in value of installed base of daylight-harvesting lighting controls $120M
Increase in aggregate annual energy savings from daylight harvesting 560 million kWh
Increase in aggregate annual dollar savings from daylight harvesting $80M
Decrease in aggregate annual CO2 emissions from daylight harvesting 400,000 metric tons
Value of IntelliBlinds™ installed base $340M

As with any market projection, the numbers of Table 1 have substantial uncertainty. However, they are conservative in that they don't consider likely growth in non-residential floor area, use of IntelliBlinds™ beyond office buildings, or sales due to new construction, major renovations, or replacement of worn-out systems. Therefore, we believe they represent an objective and reasonably accurate picture of the market potential of IntelliBlinds™.

Additional Applications

The IntelliBlinds™ Model D is targeted to the non-residential retrofit daylighting market for four reasons:

  • Daylighting saves energy and helps the environment—goals which aren't just of personal interest to the IntelliBlinds™ developers, but which also facilitate marketing.
  • As the first and only cost-effective DDC product, IntelliBlinds™ fills a recognized and long-standing gap in this particular market.
  • Costs of advertising and distribution are far lower than in other markets (e.g. the residential shading market).
  • Because there is no viable competition and because the value proposition of IntelliBlinds™ is so compelling, the potential payoff is huge—despite the fact that the overall market is relatively small.

However, the non-residential retrofit daylighting market is much more demanding than any other market in terms of the affordability and capability of automated shading technology: no other automated shading application requires DDC capability, and no other market is as sensitive to price. The ability of IntelliBlinds™ to meet these stressing requirements means that it could also achieve deep market penetration in other applications, too.

The most lucrative of these other applications is retail automated shading for residential windows. Because conventional automated shading products are too expensive, complicated, large, and difficult to install for retail distribution, this market segment is currently untapped—and potentially much larger than the target non-residential daylighting market.

IntelliBlinds™ provides a level of automation "intelligence" and usability unmatched by conventional automated shading products—at just a fraction of the cost. And because it's physically small, can be distributed separately from its host blind, and can be installed by the end-user, it's uniquely suited for retail distribution. These advantages make IntelliBlinds™ the first automated shading product capable of penetrating the residential mass market.

A residential version of IntelliBlinds™ would include some design changes, but would share approximately 90% of the daylighting version's components and tooling. Residential versions have been prototyped and tested. However, the residential market has higher costs of entry and offers limited near-term potential for energy savings. Therefore, retrofit daylighting in office buildings is currently the priority application for IntelliBlinds™.

Summary of Key Points

  • IntelliBlinds™ can enhance energy efficiency, comfort, convenience, privacy, and security in any building equipped with windows. However, it was developed to penetrate a specific, highly lucrative market segment: retrofit daylighting in office buildings
    • The potential energy savings from daylighting in office buildings are huge, and automatic daylight-harvesting lighting controls are available at low cost. But actual savings are limited by the fact that windows are typically over-shaded to order to control glare, drastically reducing the daylight available for harvesting
    • The solution was demonstrated almost two decades ago: Dynamic Daylight Control (DDC) via automated shading. However, conventional DDC technology is far too expensive for mainstream use, so the enormous potential of daylight harvesting in existing office buildings remains mostly untapped
  • But now, thanks to the IntelliBlinds™ Model D, DDC is finally cost-effective for retrofit daylighting applications
    • The IntelliBlinds™ Model D instantly converts any miniblind into a high-performance DDC system that costs only one-third as much as conventional DDC technology, yet provides even greater energy savings
    • As a result, IntelliBlinds™ significantly reduces the payback period for daylight harvesting—typically by 50%, down to a market-friendly 2–4 years
    • Like conventional DDC technology, IntelliBlinds™ also greatly reduces the risk associated with daylighting investments by eliminating savings uncertainties due to manually operated shading
    • But unlike conventional DDC technology, IntelliBlinds™ works with all daylight-harvesting lighting controls and requires no connections to the lighting system, greatly simplifying distribution and installation
  • Using published single-parameter market penetration models based solely on payback period—and neglecting the other benefits—the IntelliBlinds™ Model D is projected to:
    • Increase the installed base of daylight-harvesting lighting controls by 220 million square feet, with IntelliBlinds™ itself achieving an installed base of 590 million square feet
    • Increase aggregate energy savings from daylight harvesting by 560 million kWh per year
    • Reduce CO2 emissions by another 400 thousand metric tons per year
    • Boost aggregate dollar savings from daylight harvesting by $80 million per year
    • Boost the cumulative sales of daylight-harvesting lighting controls by $120 million, with IntelliBlinds™ itself generating $340 million of cumulative sales at ultimate market penetration
  • And these projections are conservative in that they don't consider likely growth in non-residential floor area, use of IntelliBlinds™ beyond office buildings, or sales due to new construction, major renovations, or replacement of worn-out systems
Cost-effective dynamic daylight control for non-residential daylighting
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