Daylighting Resources - Design Guides
Retail Sales | Energy Savings | Office Rental Value | Windows | Blinds | Shading Devices | Light Shelves | Skylights | Offices | Retail | Schools | Warehousing
Retail Sales
There is some indication that providing daylight though skylights in deep buildings without any other form of daylight has a small but positive effect on sales. Whether this is due to changes in visibility of merchandise, changes in store appearance, or changes in architecture, is open to question.
Anecdotal reports and daylighting policies
The benefits of lighting for selling have been the subject of anecdotal reports (Pierson, 1995; Edwards and Torcellini, 2002). These reports describe architectural daylighting policies adopted by a number of national chain stores including Wal-Mart, Target and REI, and consistently report increases in retail sales, improvements in employee morale, and savings in electrical energy. However, these reports contain little numerical evidence, and there is clearly an extent to which commercial organizations might emphasize positive outcomes.
Evidence for increases in retail sales
Boyce et al. (1996) monitored sales during a process of upgrading the visual environment of a small supermarket. Electric lighting was improved throughout the store, and skylights were added in the bakery. Statistically significant, sustained increases in the dollar value of sales were recorded in the bakery, but not in other areas of the store, suggesting that the provision of daylight was the cause of the increase.
Probably the most convincing evidence that daylight can have an influence on sales is a study of sales in a retail chain operating 108 stores, two-thirds with diffusing skylights and one-third without (Heschong-Mahone, 1999; Heschong et al., 2002a). The design, operation and layout of all the stores were very similar. The only obvious differences between the stores with skylights and those without, were the generally higher ceilings. After dark, the appearance of all the stores was similar. By day, light levels under the skylights were often much higher than those provided by the electric lighting in the stores without skylights.
The effect of eight different factors on the sales index was examined using stepwise multiple linear regression, and the presence of skylights was found to explain 4% of the variation in sales income between stores. This compares with 16% explained by differences in the hours of opening, and 9% by the age of the store.
Correlation and causality
Of course, a statistically significant regression does not itself prove a causal link. There may be other unconsidered factors that are themselves correlated with sales index and the presence of skylights, but at least there is some evidence that the lighting conditions provided by the skylights are appreciated; interviews with shoppers in the skylit stores revealed an almost total lack of awareness of the skylights but a clear perception that the store was cleaner and more spacious than other similar stores. This suggests that it was the contribution of the skylight to the visual environment in the store that was responsible for the impact on the sales index. If this is so, then there are many ways to create an attractive visual environment in a store, the use of skylights being just one.
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Energy Savings
If a workplace is well lit by daylight, then electric lighting can be dimmed or switched off, creating a reduction in lighting electricity bills. In some buildings, windows may increase heating bills in the winter because they are poor thermal insulators. Windows may also increase air conditioning bills in the summer if direct sunlight is allowed to enter the buildings.
Energy cost savings in practice are highly dependent on the behavior and cultural values of occupants—if occupants are provided with opaque aluminum blinds and leave them closed all the time to ensure privacy, then no lighting energy savings are possible. If occupants value daylight and the view out, or are motivated to minimize energy costs, substantial savings are possible.
Typical cost of lighting energy
Electricity for lighting typically costs 60 cents per square foot per year, or approximately $60 per year per employee (assuming a typical lighting energy density of 1.5 watts per square foot (W/ft2), office occupancy from 08:00 to 18:00, 100 square feet per employee, 12 cents per kWh electricity cost, and that 0.35 watts of air conditioning are required to remove one Watt of lighting heat).
Sixty dollars per employee is a very low sum compared to the cost of hiring, training, paying, managing and retaining that employee, and so the primary goal in the use of daylight should be to improve employees’ working environment and to cause them no undue annoyance or discomfort. Unsuccessful energy-saving schemes focus only on the cost savings to the company, whereas successful schemes focus on creating pride in the workplace, improved morale and an awareness of shared responsibilities and benefits.
Energy-saving potential of various lighting control systems
The energy saved by any lighting control system varies very widely depending on the size and layout of the office, the size of the windows, and any partitioning systems used. All energy savings are quoted relative to a baseline of the lights being switched on all the time.
- Single-occupant or small shared offices
A simple light switch is an effective energy-saving device because it allows occupants to easily switch their lights on when required, or to leave them switched off if daylight is providing sufficient light (Hunt, 1979). Light switches are appropriate when occupants are controlling only their own lights, or those of a small group of co-workers. Switches should be positioned close to the light fixtures in order to maximize usage (California Energy Commission, 2003). Lighting energy savings of around 30% are typical for small offices, but vary widely depending on the size and type of windows, and the motivation and preferences of the occupant(s) (Newsham, 1994).
Automatic systems that switch off or dim the lights in response to daylight are highly effective in single daylit offices. Reinhart (2002) found that energy savings of 50% were possible in conjunction with a manually-operated blind system, and that savings could reach 70% if the blind were optimally controlled either by occupants or by an automatic system.
- Large open-plan offices
In open plan offices it is difficult to provide light switches close to the fixtures, unless local task lighting is used, or unless an expensive, addressable control system is installed. Occupants of shared space are often reluctant to use light switches for fear of creating conflict with their co-workers (Moore et al., 2003).
A system that automatically controls the lights in the response to the amount of daylight is the most effective way of saving energy in open-plan spaces. Systems that progressively dim the lights are preferred to those that switch them off, because the operation of the automatic system is less noticeable to occupants. Occupants should always be provided with a simple means of overriding the automatic system, otherwise complaints may lead to the system being decommissioned.
Lighting energy savings for automatic systems vary widely depending on the size and type of windows; Reinhart (2002) showed that a typical 30’ deep office with dimming controls could save approximately 40% of lighting energy in conjunction with manually-controlled window blinds. Switching systems are not effective at distances of more than 10-15’ from windows.
- Large partitioned offices
Partitions dramatically reduce the transmission of daylight into an office, and the resulting energy savings, compared with open-plan offices. Reinhart (2002) showed that 72” partitions halved daylight levels in an office 15’ from the windows, compared with 48” partitions. Therefore automatic dimming or switching systems will only achieve significant energy savings in the first row of offices with high partitions.
Skylights
Skylights are a particularly effective source of daylight because they admit light from the brightest part of the sky (the zenith), but seldom cause glare because they are above the typical visual field of occupants. Skylights are complementary to windows, since windows illuminate the perimeter of a space, whereas skylights can illuminate its center.
The use of skylights can reduce the electric lighting requirement of an entire space during daylight hours to almost zero, but they must be designed to shade the space from direct sunlight (Heschong-Mahone Group, 1998).
Strategies for maximizing energy savings
- Light-colored walls and furnishings increase the amount of daylight in a space and improve visual comfort by reducing contrast. The areas around the windows are especially important.
- Removing clutter from the window sill and the floor around the window, and using a light colored carpet or rug will significantly improve the transmission of daylight into the space.
- Light switches should be clearly labeled to show which light fixtures they control. This will reduce people’s uncertainty and make them more likely to turn lights off, or switch on only the lights they require.
- A simple “light shelf” made of a light-colored material, approximately 18” deep and placed horizontally about 2-3’ below the top of the window will brighten the upper walls and ceiling around the window, reducing contrast and improving visual comfort. This will make occupants less likely to switch their lights on.
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Office Rental Value
There is anecdotal evidence that the complete absence of windows reduces the rent that can be asked for an office by $2-$4 per square foot. This represents a 10%-20% reduction in rental value for typical urban office space costing between $15 and $20 per square foot. The value of office space can also be increased if it meets an environmental accreditation program such as LEED; daylight admission is an integral part of such programs.
The profitability of rented office space is significantly affected by the time for which it stands vacant, which may in turn be affected by the daylit appearance of the space.
Daylight has a symbolic and status-creating role in architecture, and its presence or absence may influence the renting decisions of prestige tenants.
Costs due to time vacant
Office space is typically vacant 3% of the time, or approximately four months before and after a market-average ten year lease; this incurs significant opportunity costs for the owner. A survey of tenants has shown that poor indoor air quality and the related issues of thermal comfort and air conditioning performance are cited by 24% of tenants as common reasons for moving out of a property (BOMA, 1988). If these problems could be eliminated, the estimated productivity gain would be 18%. The percentage of tenants thinking that windows were the worst problem was 2.1% and the estimated productivity gain was 4%.
This survey does not deal directly with issues such as daylight glare, solar discomfort or gloom, but it is reasonable to assume that daylight-related factors are also involved in tenants’ decisions to move out, and may be a greater factor in their decisions to move in, due to the immediate nature of visual comfort issues.
Mudarri (2000) provides an example of the return on investment of an improved physical environment. In this calculation, he argues that tenant retention is valuable to a building owner. By retaining a tenant on a new lease, the owner avoids the expenses associated with buildout and brokerage fees, as well as the lost income associated with the time the building stands empty.
During periods of slow economic growth prospective tenants have the choice of a wide variety of spaces and are unlikely to prefer a dim, poorly daylit office. This may cause a property to stand vacant for periods in excess of the market average.
Status and prestige of daylight
In comparison to curtain walling, windows are both expensive and poorly insulating. Means Light Commercial Cost Data (Means, 2002) gives typical costs per unit area of $4.25 per square foot installed for concrete block walls, $5.90 per square foot installed for tilt-up concrete wall panels, and $19.55 per square foot for exterior brick face cavity wall, versus $20.70 per square foot installed for the cheapest form of glazed curtain wall.
Against this background of additional costs, the continuing widespread use of windows in commercial buildings requires some explanation. Why do developers continue to invest in these costly elements? Part of the answer is no doubt the widespread preference for daylight as the main light source in a space. Another is probably the role of windows and atria as corporate status symbols; there is an evident correlation between the widespread use of daylighting, through either extensive glazing or large atria, and the prestige of the building. An explanation of this can be given in terms of the demagogic function of commercial buildings. For this role the presence of windows or atria may function much like the presence of marble cladding—to impress and intimidate. Another explanation can be found in the use of daylight provision as a reflection of the status of the occupants. The rise of an individual to prominence in an organization can be seen by the closeness of that occupant to windows.
Voluntary environmental accreditation programs
Voluntary accreditation schemes range from the truly voluntary to the almost mandatory, and they have the potential to influence the capital and rental value of a building. In the UK, around 25% of offices now carry voluntary (BREEAM) environmental accreditation, and the accreditation is widely understood and valued by property agents in the UK.
The best-known accreditation scheme in the US is the Leadership in Energy and Environmental Design (LEED) (US Green Buildings Council, 2002). This accreditation system was established in 1999 by the US Green Buildings Council, and has recently published a pilot for the LEED-CI Rating System for Commercial [office] Interiors. This accreditation is entirely voluntary, and to acquire it, a building owner must prove that the building meets certain environmental standards for sustainability, efficiency, and indoor environmental quality. Of the 57 available credits, two involve daylighting. Specifically, one credit can be obtained by ensuring a minimum of 2% daylight factor over 75% of the floorspace, and another by ensuring a direct line of sight to vision glazing from 90% of the floorspace.
Mandatory environmental performance targets
Although most states do not yet have mandatory building energy targets, the requirements of Title 24 (California Energy Commission, 2003) are leading the way to mandatory limitations on lighting energy consumption.
The 2003 amendments to Title 24, to be implemented in 2005, state that office buildings must use no more than 1.1 W/ft2 for lighting. This figure is difficult to meet without the use of “adjustment factors” which take account of the presence of lighting control systems including motion sensors, manual switches, and photoelectric controls. The adjustment factor allowed for installing photoelectric controls depends on the window area of the façade and the transmittance of the windows, but can be up to 40%.
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Windows
Title: LEED Green Building Rating System
Author(s): LEED (Leadership in Energy and Environmental Design)
Reference: LEED (Leadership in Energy and Environmental Design)
Publication Organization: US Green Building Council
Publication URL: http://www.usgbc.org/LEED/LEED_main.asp
Abstract: The LEED (Leadership in Energy and Environmental Design) Green Building Rating System™ is a voluntary, consensus-based, national standard for developing high-performance, sustainable buildings. LEED certification assures the tenant that a building reaches high standards of energy performance, while creating comfortable environmental conditions for occupants. Of the 69 credits available for new contrusction within the LEED system, one can be obtained by assuring a minimum of 2% daylight factor over 75% of the floorspace, and another can be obtained by ensuring a direct line of sight to vision glazing from 90% of the floorspace. Similar LEED credits designations are being developed for existing building, commercial interiors, and core and shell projects.
Title: California Energy Commission 2005 Building Energy Efficiency Standards (Title 24)
Author(s): G. William Pennington, Jon Leber
Reference: G. William Pennington, Jon Leber
Publication Organization: California Energy Commission
Publication URL: http://www.energy.ca.gov/2005_standards/index.html
Abstract: The California Building Code establishes building energy efficiency standards for new construction (including requirements for entire new buildings, additions, alterations, and in non-residential buildings, repairs). The Code requires that office buildings use no more than 1.1w ft2 for lighting; this figure is very difficult to achieve without the use of 'adjustment factors' which take account of the presence of lighting control systems, including daylight linking. Large windows with high transmittance glazing allow adjustment factors of up to 40% to be used. The next update to California's energy efficiency standards for residential and non-residential buildings (Title 24, Part 6) is expected to be adopted by the Commission by July 1, 2003, and go into effect in 2005.
Title: The significance of sunshine and view for office workers
Author(s): Markus, TA
Reference: Markus, T.A., (1967) The significance of sunshine and view for office workers, in R.G. Hopkinson (ed) Sunlight in Buildings, Boewcentrum International: Rotterdam, The Netherlands.
Abstract: In an extensive study, 95% of office occupants preferred daylight to electric lighting. Those nearer to windows were more satisfied with their daylight than those further away, particularly on the lower floors. This effect could be attributable to the view out of the building, or to the amount of daylight. Occupants near the south-east and south-west walls were more satisfied with their daylight than those near the north-west and north-east walls. This may be because they value the availability of direct sunlight, or it may be due to window glare being more severe through north-facing windows. The study surveyed 400 office workers on nine floors of a 12-story open-plan building.
Title: Effect of window size and sunlight presence on glare
Author(s): Boubekri, M, Boyer, LL
Reference: Boubekri, M. and L. L. Boyer (1992), Effect of Window Size and Sunlight Presence on Glare, Lighting Research and Technology, 24 (2): 69-74
Abstract: Occupants’ assessments of glare from south-facing windows were found to be lower than predicted by daylight glare index calculations. The authors ascribe this difference to the presence of direct sunlight, and to the pleasant rural view from the window. Daylight glare varied according to window area, reaching a maximum when the windows occupied 50% of the facade. Fifty percent is a typical value for many commercial buildings, so the results suggest that current daylighting practice may be suboptimal with regard to glare.
Title: Glare from windows -3. Using the glare index in daylighting design
Author(s): Hopkinson, R
Reference: Hopkinson, R. G. (1971) Glare from windows - 3 using the glare index in daylighting design. Construction Research and Development Journal 3(1), 23-28.
Abstract: Interior window reveals can reduce glare from windows. Reveals are usually sections of light-colored angled wall surrounding a window, and are used to create an area of intermediate luminance between the window and the interior wall. A window surrounded by a reveal of one-sixth of its linear dimension can reduce glare by up to two points on a 12-point scale ranging from 16 (imperceptible) to 25 (intolerable).
Title: Daylight and the appearance of indoor surfaces
Author(s): Lynes, J
Reference: Lynes, J. (1994). “Daylight and the appearance of indoor surfaces.” Proceedings of the CIBSE National Lighting Conference 1994, 98-110.
Abstract: High contrasts (glare) around windows make it impossible for occupants to distinguish colors on surfaces immediately surrounding the window. This ‘failure of lightness constancy’ can be characterized as ‘gloom’ and plausibly accounts for the observed tendency of people to switch electric lighting on when they enter a room. Electric lighting reduces the contrast between the window and the wall, and makes colors visible once more. Glare and gloom are closely linked, and both can be reduced by increasing the ‘daylight factor', i.e., by adding more daylight into the room. Lynes provides graphs that can be used to determine the minimum value of wall reflectance for a given daylight factor (or vice-versa). Lynes’ calculations are based on Hunt’s (1991) color model.
Title: Circadian photobiology: An emerging framework for lighting practice and research
Author(s): Rea, MS, Figueiro, MG, Bullough, JD
Reference: Rea, Mark S., Mariana G. Figueiro, and John D. Bullough. (2002) Circadian Photobiology: an Emerging Framework for Lighting Practice and Research. Lighting Research and Technology 34(3), 177-190.
Abstract: Lighting can be used to strengthen the human circadian rhythm, which determines various physiological functions such as sleep, digestion, alertness, depression, and probably general health. Daylight is much more effective than electric lighting at ‘entraining’ the circadian system; this is because the circadian system responds only to high levels of blue light, such as those found in daylight. Rea et al. calculate ‘circadian efficacies’ for various light sources, and find that daylight is three to four times more effective than fluorescent lamps, and twenty times more effective than incandescent lamps. They find that "light levels approaching those found outdoors in daylight are sufficient for regulation of the circadian clock and the melatonin cycle, but many indoor light levels are too low."
Title: Status in organizations: Where evolutionary theory ranks
Author(s): Waldron, D
Reference: Waldron, D. (1998). Status in Organizations: Where Evolutionary Theory Ranks. Managerial and Decision Economics (19), 505-520.
Abstract: The desire for status is one of the strongest sources of motivation for employees. This paper cites Halloran (1978) in stating that proximity to windows, and the number of windows in an office, is a common and widely understood expression of status. The author does not discuss whether the provision of windows enhances the overall status of a building or a company, or whether the effect exists only within organizations. The author makes a distinction between status and hierarchy: the former being an informal system of signs (“status symbols”) and behaviors; the latter being a more formal organizational structure expressed in job titles and remuneration. Status appears to be a pervasive phenomenon in organizations, as it is in all societies, and may be genetically or instinctually based since it is exhibited by other ape species.
Title: Innovative daylighting: Review of systems and evaluation methods
Author(s): Littlefair, PJ
Reference: Littlefair, P.J. (1990). Innovative daylighting: review of systems and evaluation methods. Lighting Research and Technology 22(1), 1-17.
Abstract: A survey of advanced daylighting technologies, including sun-gathering heliostat-lightpipe systems, light shelves, prismatic and holographic glazing. This report finds that heliostat systems are ineffective for general illumination; a 2m (6’) diameter mirror would produce only as much useful light as seven 1.5m (5’) fluorescent tubes, and would only work when the sun shines. Light shelves are found to be effective at increasing the light level at the back of a room, but only when the sun shines; otherwise they reduce the total amount of daylight in the room. Blinds are still required in addition to light shelves, to block low-angle winter sun. In general, light-gathering and redirecting systems are found to reduce the total amount of daylight entering a space, although they subdue glare from direct sunlight, and redirect diffuse light onto surfaces around the window to reduce window glare.
Title: Minimum acceptable transmittance of glazing
Author(s): Boyce, P
Reference: Boyce, P. (1995). Minimum acceptable transmittance of glazing. Lighting Research and Technology 27(3), 145-152
Abstract: Tinted windows with low transmittances should not be used, because occupants rate them as being ‘too dark.' Occupant acceptance of tinted windows falls below 85% when visible light transmittance is around 38% under overcast (cloudy) skies, though transmittances as low as 25% may be acceptable under clear (sunny) skies. The color of the glass—neutral or bronze—was found to slightly affect the minimum acceptable transmittance, but not in a consistent or predictable way. Real window glass samples were used in a 1/12 scale model office placed outdoors. The model office had a ribbon window occupying 42% of the wall area. There were no windows in the other walls. The authors do not suggest upon what basis occupants make their judgments of acceptability.
Title: Enclosure systems
Publication Organization: Northwest Energy Alliance (Better Bricks)
Publication URL: http://www.betterbricks.com/graphics/assets/documents/DesignSystemEnvelopguideline_pa.pdf
Abstract: Discussion of the available options for building enclosure (facade) systems, including external shading devices and internal light shelves. The effect of these systems on visual comfort inside buildings, and upon HVAC systems is discussed. Visual comfort issues include: avoiding excessive contrast and solar glare; maximizing the amount of natural light and visual stimulation. The limitations of light shelves and external shading devices are described, along with the importance of multi-factorial design in producing successful buildings. Differences in local climate are addressed, and a checklist for successful design is provided.
Title: Which glass should I use? Sorting it all out
Publication Organization: Northwest Energy Alliance (Better Bricks)
Publication URL: http://betterbricks.com/DetailPage.aspx?ID=808
Abstract: A guide to the main parameters determining glazing performance, including visible light transmission (VLT), solar heat gain coefficient (SHGC), and U-factor. Advice on the selection of glazing is given: what VLT to choose; when to use clear versus diffuse glass; the benefits of fritting; laminates and smart windows. The National Fenestration Rating Council is cited as a good source of theoretical and practical information.
Title: Advanced Lighting Guidelines, pages 7-24 to 7-28
Author(s): Benya, J, Heschong, L, McGowan, T, Miller, NJ
Reference: Benya, Heschong, McGowan, Miller, Rubinstein
Publication Organization: New Buildings Institute
Publication URL: http://www.newbuildings.org/lighting.htm
Abstract: This section of the Advanced Lighting Guidelines contains definitions of key window performance parameters including U-factor, solar heat gain coefficient, visible light transmittance. A table of typical values for various glass types is given. The materials and techniques used in manufacturing low-emissivity coatings, diffusing glass, tinted glass and fritted glass are discussed. Some conceptual advice on sizing and positioning of windows is given on page 7-35. Click on "Advanced Lighting Guidelines: 2003 Edition" on the site's homepage to view reference. Site requires submittal of user information to view PDF file.
Title: Design Brief: Glazing
Publication Organization: Energy Design Resources
Publication URL: http://www.energydesignresources.com/resource/20/
Abstract: This document introduces the principles used to assess the performance of glazing, including transmission and reflectance values, and the effect of glazing on the spectral distribution of indoor light. Glazing terminology such as "thermal break" and "low-emissivity" is also explained. Examples are given of a whole-building lifecycle analysis and future glazing technologies are discussed. Special consideration is given to California energy codes.
Title: Tips for daylighting with windows: Envelope and room decisions (pages 3-1 to 3-7)
Author(s): O'Connor, J, Lee, ES, Rubinstein, F, Selkowitz, S
Publication Organization: Lawrence Berkeley National Laboratory
Publication URL: http://windows.lbl.gov/pub/designguide/section3.pdf
Abstract: This guide gives design advice that explores the purpose, positioning, sizing and detailing of windows. Many sketches are used to show a wide range of possible design options, and the consequences of design choices such as glazing transmission, room depth, furniture layout, desk orientation, and light shelves.
Title: Window Systems for High-Performance Buildings
Author(s): John Carmody, et. al.
Reference: Carmody, John, et. al., (2004), Window Systems for High-Performance Buildings, W. W. Norton & Company, Inc., 500 Fifth Avenue, New York, NY 10110
Abstract: This reference book guides the reader through the selection and design of window systems for commercial buildings. It presents information on different window materials and assemblies and their effect on energy use, daylighting strategies, glare, view and thermal comfort. The book describes a decision making process for selecting windows for different climates and for different building facade orientations.
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Blinds
Title: Innovative daylighting: Review of systems and evaluation methods
Author(s): Littlefair, PJ
Reference: Littlefair, P.J. (1990). Innovative daylighting: review of systems and evaluation methods. Lighting Research and Technology 22(1), 1-17.
Abstract: A survey of advanced daylighting technologies, including sun-gathering heliostat-lightpipe systems, light shelves, prismatic and holographic glazing. This report finds that heliostat systems are ineffective for general illumination; a 2m (6’) diameter mirror would produce only as much useful light as seven 1.5m (5’) fluorescent tubes, and would only work when the sun shines. Light shelves are found to be effective at increasing the light level at the back of a room, but only when the sun shines; otherwise they reduce the total amount of daylight in the room. Blinds are still required in addition to light shelves, to block low-angle winter sun. In general, light-gathering and redirecting systems are found to reduce the total amount of daylight entering a space, although they subdue glare from direct sunlight, and redirect diffuse light onto surfaces around the window to reduce window glare.
Title: Window blind occlusion: A pilot study, building and environment
Author(s): Rea, MS
Reference: Rea, M.S., (1984) Window blind occlusion: A pilot study, Building and Environment, 19, 133-137.
Abstract: Building occupants seldom adjust their window blinds during the course of the day; they tend to leave their blinds closed even when glare-free diffuse daylight could be admitted. Window blinds are typically more than 50% occluded. It might be expected that occupants would close blinds to exclude sunlight, and open them again under cloudy skies to admit more daylight, but results suggest that occupants set their blinds to a position in which solar glare is sufficiently excluded under most sky conditions, and leave the blinds in that position for weeks, months or years. 555 window blinds in an office building were monitored using photographs of the façade. The east, south and west facades had an average of 50%, 66% and 62% occlusion respectively. Between cloudy days and sunny days, these occlusions varied up or down from the average by 10%, 1% and 2% respectively. The east façade showed significantly more variation than the other facades, though no explanation for this is offered. These results are similar to results found previously by Rubin.
Title: Advanced optical daylighting systems: Light shelves and light pipes
Author(s): Beltran, LO, Lee, ES, Selkowitz, SE
Reference: Beltran, L.O., Lee, E.S. and Selkowitz, S.E. (1997). Advanced optical daylighting systems : light shelves and light pipes. Journal of the Illuminating Engineering Society of North America, 26(2), 91-106
Abstract: This study gives numerical values for light levels and potential lighting energy savings for several daylight redirection systems. These included single and multi-level light shelves with both matt and specular top surfaces, and sealed specular ‘light pipes’ hidden within the ceiling void. All systems were intended to reduce light levels near the window and redirect light to the back of the space. Calculations under one year of ‘average’ skies, i.e., a statistically typical combination of sunny and overcast conditions, showed that standard clear glass windows gave the highest light levels and highest potential lighting energy savings. Prismatic light pipes gave the second highest energy savings, and light shelves the lowest. Of the light shelf designs tested, the ‘base case’ design gave highest potential lighting electricity saving. Under sunny skies, all the specular light shelves and light pipes were effective at increasing light levels at the back of the space, compared to standard clear glass windows. The light pipes used in the study take up a significant proportion of the ceiling void and would necessitate unorthodox HVAC ducting.
Title: Effects of interior design on daylight availability in open-plan offices
Author(s): Reinhart, CF
Publication Organization: National Research Council of Canada
Publication URL: http://irc.nrc-cnrc.gc.ca/fulltext/nrcc45374/nrcc45374.pdf
Abstract: An investigation of the daylighting effect of design variables including: blinds, partition height, and ceiling and partition reflectance. The results show that, when complemented by a daylight-linked lighting system, blinds closed at 45 degrees can save up to 26% of lighting energy, manual blinds can save 41%, and automatic blinds 58%; all energy savings are in comparison to full installed load. Peripheral offices can typically save 25%-60% of their lighting energy by daylight-linking, and second-row offices can save 20%-40%. The results were obtained by computer modelling of a south-facing office with ribbon windows and clear glazing, using New York City climatic data.
Title: Tips for daylighting with windows: Shading strategy (pages 5-1 to 5-5)
Author(s): O'Connor, J, Lee, ES, Rubinstein, F, Selkowitz, S
Publication Organization: Lawrence Berkeley National Laboratory
Publication URL: http://windows.lbl.gov/pub/designguide/section5.pdf
Abstract: A step-by-step guide to choosing, sizing and specifying architectural window shades. Many sketches are used to show the various design options, and how each one modifies the way the daylight is admitted in to the building. The use of sunpath diagrams to design window shading is clearly explained. Key items are checklisted in order of priority to help the time-pressured architect.
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Shading Devices
Title: The significance of sunshine and view for office workers
Author(s): Markus, TA
Reference: Markus, T.A., (1967) The significance of sunshine and view for office workers, in R.G. Hopkinson (ed) Sunlight in Buildings, Boewcentrum International: Rotterdam, The Netherlands.
Abstract: In an extensive study, 95% of office occupants preferred daylight to electric lighting. Those nearer to windows were more satisfied with their daylight than those further away, particularly on the lower floors. This effect could be attributable to the view out of the building, or to the amount of daylight. Occupants near the south-east and south-west walls were more satisfied with their daylight than those near the north-west and north-east walls. This may be because they value the availability of direct sunlight, or it may be due to window glare being more severe through north-facing windows. The study surveyed 400 office workers on nine floors of a 12-story open-plan building.
Title: Effect of window size and sunlight presence on glare
Author(s): Boubekri, M, Boyer, LL
Reference: Boubekri, M. and L. L. Boyer (1992), Effect of Window Size and Sunlight Presence on Glare, Lighting Research and Technology, 24 (2): 69-74
Abstract: Occupants’ assessments of glare from south-facing windows were found to be lower than predicted by daylight glare index calculations. The authors ascribe this difference to the presence of direct sunlight, and to the pleasant rural view from the window. Daylight glare varied according to window area, reaching a maximum when the windows occupied 50% of the facade. Fifty percent is a typical value for many commercial buildings, so the results suggest that current daylighting practice may be suboptimal with regard to glare.
Title: Windows and daylight - A post-occupancy evaluation of offices
Author(s): Christoffersen, J, Petersen, E, Johnsen, K, Valbjorn, O
Reference: Statens Byggeforskningsinstitut. (1999). Report 318: Windows and Daylight - a Post-occupancy Evaluation of Offices. Horsholm, Denmark.
Publication Organization: Statens Byggeforskningsinstitut, Horsholm, Denmark
Abstract: A survey of 2340 Danish office workers found that there is a strong preference for having the workstation close to a window, despite a higher incidence of glare and reflections on PC screens. Occupants' satisfaction with their daylighting was strongly positively correlated with measured daylight factor. Sixty percent of occupants wished to have direct sunlight in their office during at least one season of the year. More than 50% of respondents reported no negative aspects of their windows; of the problems reported, glare was the most frequent, followed by heat discomfort. The degree of dissatisfaction with daylighting increased with the number of people in the office.
Title: Productivity in buildings: The "killer" variables
Author(s): Leaman, A, Bordass, B
Reference: Leaman, A., and Bordass, B. (2000) Productivity in buildings: The "killer" variables, in Creating the Productive Workplace, ed: D. Clements-Croome, E. & F. N. Spon: London.
Abstract: An extensive series of post-occupancy evaluations of office buildings (known as the ‘PROBE’ studies) led to the identification of four ‘killer’ variables that have a critical influence on productivity. These are labeled ‘personal control’, ‘responsiveness to complaints’, ‘building depth’, and ‘workgroup’. Designers can influence ‘personal control’ by designing easy-to-use lighting and ventilation control systems, and openable windows. Designers can also influence ‘building depth.’ For ‘personal control’ there was a small but statistically significant correlation (r = 0.16 to 0.49) between level of individual control of the environment and self-reported productivity in seven of eleven office buildings evaluated. Results suggest that personal control is most valued when there is a source of discomfort such as glare or solar heat, i.e., when personal control enables the individual to adjust the conditions until comfort is achieved. For this reason, all windows should have some means of controlling the admission of daylight and sunlight to ensure comfort. For ‘building depth’, as buildings get deeper, the levels of satisfaction with the building and self-reported productivity decrease. The critical threshold depth appears to be about 15 m (50’) from wall to wall, when both walls are glazed. The percentage of people satisfied with the building was closely correlated with the percentage of people sitting next to windows.
Title: Window blind occlusion: A pilot study, building and environment
Author(s): Rea, MS
Referenc: Rea, M.S., (1984) Window blind occlusion: A pilot study, Building and Environment, 19, 133-137.
Abstract: Building occupants seldom adjust their window blinds during the course of the day; they tend to leave their blinds closed even when glare-free diffuse daylight could be admitted. Window blinds are typically more than 50% occluded. It might be expected that occupants would close blinds to exclude sunlight, and open them again under cloudy skies to admit more daylight, but results suggest that occupants set their blinds to a position in which solar glare is sufficiently excluded under most sky conditions, and leave the blinds in that position for weeks, months or years. 555 window blinds in an office building were monitored using photographs of the façade. The east, south and west facades had an average of 50%, 66% and 62% occlusion respectively. Between cloudy days and sunny days, these occlusions varied up or down from the average by 10%, 1% and 2% respectively. The east façade showed significantly more variation than the other facades, though no explanation for this is offered. These results are similar to results found previously by Rubin.
Title: Enclosure systems
Publication Organization: Northwest Energy Alliance (Better Bricks)
Publication URL: http://www.betterbricks.com/graphics/assets/documents/DesignSystemEnvelopguideline_pa.pdf
Abstract: Discussion of the available options for building enclosure (facade) systems, including external shading devices and internal light shelves. The effect of these systems on visual comfort inside buildings, and upon HVAC systems is discussed. Visual comfort issues include: avoiding excessive contrast and solar glare; maximizing the amount of natural light and visual stimulation. The limitations of light shelves and external shading devices are described, along with the importance of multi-factorial design in producing successful buildings. Differences in local climate are addressed, and a checklist for successful design is provided.
Title: Advanced Lighting Guidelines, pages 7-19 to 7-22, 7-35 to 7-38
Author(s): Benya, J, Heschong, L, McGowan, T, Miller, NJ
Publication Organization: New Buildings Institute
Publication URL: http://www.newbuildings.org/lighting.htm
Abstract: This section of the Advanced Lighting Guidelines contains information about the technologies and techniques available for shading and daylight redirection, including external louvers, light shelves and opaque blinds. Photographs of installed systems are shown. Practical advice on the design and positioning of light shelves, though no quantitative information about the effect of these devices on light distribution is given. Click on "Advanced Lighting Guidelines: 2003 Edition" on the site's homepage to view reference. Site requires submittal of user information to view PDF file.
Title: Tips for daylighting with windows: Shading strategy (pages 5-1 to 5-5)
Author(s): O'Connor, J, Lee, ES, Rubinstein, F, Selkowitz, S
Publication Organization: Lawrence Berkeley National Laboratory
Publication URL: http://windows.lbl.gov/pub/designguide/section5.pdf
Abstract: A step-by-step guide to choosing, sizing and specifying architectural window shades. Many sketches are used to show the various design options, and how each one modifies the way the daylight is admitted in to the building. The use of sunpath diagrams to design window shading is clearly explained. Key items are checklisted in order of priority to help the time-pressured architect.
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Light Shelves
Title: Innovative daylighting: Review of systems and evaluation methods
Author(s): Littlefair, PJ
Reference: Littlefair, P.J. (1990). Innovative daylighting: review of systems and evaluation methods. Lighting Research and Technology 22(1), 1-17.
Abstract: A survey of advanced daylighting technologies, including sun-gathering heliostat-lightpipe systems, light shelves, prismatic and holographic glazing. This report finds that heliostat systems are ineffective for general illumination; a 2m (6’) diameter mirror would produce only as much useful light as seven 1.5m (5’) fluorescent tubes, and would only work when the sun shines. Light shelves are found to be effective at increasing the light level at the back of a room, but only when the sun shines; otherwise they reduce the total amount of daylight in the room. Blinds are still required in addition to light shelves, to block low-angle winter sun. In general, light-gathering and redirecting systems are found to reduce the total amount of daylight entering a space, although they subdue glare from direct sunlight, and redirect diffuse light onto surfaces around the window to reduce window glare.
Title: Advanced optical daylighting systems: Light shelves and light pipes
Author(s): Beltran, LO, Lee, ES, Selkowitz, SE
Reference: Beltran, L.O., Lee, E.S. and Selkowitz, S.E. (1997). Advanced optical daylighting systems : light shelves and light pipes. Journal of the Illuminating Engineering Society of North America, 26(2), 91-106
Abstract: This study gives numerical values for light levels and potential lighting energy savings for several daylight redirection systems. These included single and multi-level light shelves with both matt and specular top surfaces, and sealed specular ‘light pipes’ hidden within the ceiling void. All systems were intended to reduce light levels near the window and redirect light to the back of the space. Calculations under one year of ‘average’ skies, i.e., a statistically typical combination of sunny and overcast conditions, showed that standard clear glass windows gave the highest light levels and highest potential lighting energy savings. Prismatic light pipes gave the second highest energy savings, and light shelves the lowest. Of the light shelf designs tested, the ‘base case’ design gave highest potential lighting electricity saving. Under sunny skies, all the specular light shelves and light pipes were effective at increasing light levels at the back of the space, compared to standard clear glass windows. The light pipes used in the study take up a significant proportion of the ceiling void and would necessitate unorthodox HVAC ducting.
Title: Enclosure systems
Publication Organization: Northwest Energy Alliance (Better Bricks)
Publication URL: http://www.betterbricks.com/graphics/assets/documents/DesignSystemEnvelopguideline_pa.pdf
Abstract: Discussion of the available options for building enclosure (facade) systems, including external shading devices and internal light shelves. The effect of these systems on visual comfort inside buildings, and upon HVAC systems is discussed. Visual comfort issues include: avoiding excessive contrast and solar glare; maximizing the amount of natural light and visual stimulation. The limitations of light shelves and external shading devices are described, along with the importance of multi-factorial design in producing successful buildings. Differences in local climate are addressed, and a checklist for successful design is provided.
Title: Advanced Lighting Guidelines, pages 7-19 to 7-22, 7-35 to 7-38
Author(s): Benya, J, Heschong, L, McGowan, T, Miller, NJ
Publication Organization: New Buildings Institute
Publication URL: http://www.newbuildings.org/lighting.htm
Abstract: This section of the Advanced Lighting Guidelines contains information about the technologies and techniques available for shading and daylight redirection, including external louvers, light shelves and opaque blinds. Photographs of installed systems are shown. Practical advice on the design and positioning of light shelves, though no quantitative information about the effect of these devices on light distribution is given. Click on "Advanced Lighting Guidelines: 2003 Edition" on the site's homepage to view reference. Site requires submittal of user information to view PDF file.
Title: Tips for daylighting with windows: Shading strategy (pages 5-1 to 5-5)
Author(s): O'Connor, J, Lee, ES, Rubinstein, F, Selkowitz, S
Publication Organization: Lawrence Berkeley National Laboratory
Publication URL: http://windows.lbl.gov/pub/designguide/section5.pdf
Abstract: A step-by-step guide to choosing, sizing and specifying architectural window shades. Many sketches are used to show the various design options, and how each one modifies the way the daylight is admitted in to the building. The use of sunpath diagrams to design window shading is clearly explained. Key items are checklisted in order of priority to help the time-pressured architect.
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Skylights
Title: Light Scoops: A Design Guide (2013)
Author(s): Radetsky L, Brons J
Publication URL: http://www.lrc.rpi.edu/researchAreas/pdf/LightScoopsDesignGuide_Final.pdf
Abstract: A light scoop is a south-facing skylight, developed by the Lighting Research Center (LRC) that uses tilted panels of transparent glass to strategically bring daylight into an interior space; this is most appropriate in spaces such as lobbies, shopping malls, and airports, where occupants briefly move through the space. Light scoops offer advantages over conventional horizontal skylights because they provide less light in summer, when direct sunlight can be less desirable, and more light in winter , when direct sunlight is desirable. This also has implications for heating and cooling.
Title: Innovative daylighting: Review of systems and evaluation methods
Author(s): Littlefair, PJ
Reference: Littlefair, P.J. (1990). Innovative daylighting: review of systems and evaluation methods. Lighting Research and Technology 22(1), 1-17.
Abstract: A survey of advanced daylighting technologies, including sun-gathering heliostat-lightpipe systems, light shelves, prismatic and holographic glazing. This report finds that heliostat systems are ineffective for general illumination; a 2m (6') diameter mirror would produce only as much useful light as seven 1.5m (5') fluorescent tubes, and would only work when the sun shines. Light shelves are found to be effective at increasing the light level at the back of a room, but only when the sun shines; otherwise they reduce the total amount of daylight in the room. Blinds are still required in addition to light shelves, to block low-angle winter sun. In general, light-gathering and redirecting systems are found to reduce the total amount of daylight entering a space, although they subdue glare from direct sunlight, and redirect diffuse light onto surfaces around the window to reduce window glare.
Title: Advanced optical daylighting systems: Light shelves and light pipes
Author(s): Beltran, LO, Lee, ES, Selkowitz, SE
Reference: Beltran, L.O., Lee, E.S. and Selkowitz, S.E. (1997). Advanced optical daylighting systems : light shelves and light pipes. Journal of the Illuminating Engineering Society of North America, 26(2), 91-106
Abstract: This study gives numerical values for light levels and potential lighting energy savings for several daylight redirection systems. These included single and multi-level light shelves with both matt and specular top surfaces, and sealed specular ‘light pipes’ hidden within the ceiling void. All systems were intended to reduce light levels near the window and redirect light to the back of the space. Calculations under one year of ‘average’ skies, i.e., a statistically typical combination of sunny and overcast conditions, showed that standard clear glass windows gave the highest light levels and highest potential lighting energy savings. Prismatic light pipes gave the second highest energy savings, and light shelves the lowest. Of the light shelf designs tested, the ‘base case’ design gave highest potential lighting electricity saving. Under sunny skies, all the specular light shelves and light pipes were effective at increasing light levels at the back of the space, compared to standard clear glass windows. The light pipes used in the study take up a significant proportion of the ceiling void and would necessitate unorthodox HVAC ducting.
Title: Skylighting Guidelines (Chapter 8)
Publication Organization: Heschong Mahone Group, for the Northwest Energy Efficiency Alliance
Publication URL:
Abstract: This report gives practical design guidance on the use of skylights. It gives numerical information on illumination patterns and likely energy savings by region, glazing type, building type and control type, all presented in graphical form. This report is targeted towards designers and building owners in four Pacific-Northwest states: Oregon, Washington, Idaho and Montana. It reviews the climate of the region, differing energy-code requirements in the separate states, and common building practices that affect the specification of skylights for commercial buildings.
Title: Retail skylighting knowhow
Publication Organization: Design Lights Consortium
Publication URL: http://www.designlights.org/downloads/skylighting_Retail.pdf
Abstract: This guide shows how to use skylights in retail environments to enhance a store's appearance, attract and retain shoppers, and produce savings on lighting energy costs. The guide is illustrated with sample retail layouts, and describes how skylights can be integrated with electric lighting and lighting controls to maximize energy savings. Estimated energy savings are given for each skylighting option. Systems optimized for the northeastern United States are described in detail, and the guide cites research that finds evidence of increased retail sales in stores with skylights.
Title: Classroom lighting knowhow
Publication Organization: Design Lights Consortium
Publication URL: http://www.designlights.org/downloads/classroom_guide.pdf
Abstract: This guide provides some advice on how to use photocell dimming in schools to save lighting energy without creating distraction to students. It also provides guidance on what types of luminaries to use, and how best to orient and group them in order to maximize energy savings. Estimated energy savings are given for a variety of luminaire and control options. The guide intends to “promote high-quality learning among children … via the utilization of energy-efficient applications such as daylighting and lighting controls.” (Ref: http://www.designlights.org/downloads/classroom_guide.pdf). To this end it cites research which claims that students in well daylit schools score better in exams than those in poorly daylit schools.
Title: Warehouse skylighting knowhow
Publication Organization: Design Lights Consortium
Publication URL: http://www.designlights.org/downloads/skylighting_Warehouse.pdf
Abstract: This guide shows in detail how to design skylights and daylight—linked controls in warehouses to increase energy cost savings, productivity, and worker safety while reducing maintenance costs. The guide shows how to analyze skylight designs using software such as “SkyCalc” and it gives estimated energy savings for a variety of design options. It compares the performance of metal halide and fluorescent lamps, provides illustrated equipment layouts, and addresses construction concerns.
Title: Field Test Delta: Integrated Skylight Luminaire
Publication Organization: Lighting Research Center
Publication URL: www.lrc.rpi.edu/programs/delta/pdf/fieldtestdelta.pdf
Abstract: High-bay warehouses, light industrial facilities, and big box retail stores offer the opportunity to save energy and improve occupant satisfaction by admitting daylight through their roofs. Prototypes of an Integrated Skylight Luminaire (ISL) were installed in a working warehouse and analyzed for energy savings and lighting quality. Each ISL includes a skylight, fluorescent luminaires, and a self-commissioning control system that automatically dims or switches the lamps in response to daylight. The ISL’s design and field performance are documented. Use of the ISL was shown to reduce energy consumption by up to 40%.
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Offices
Title: LEED Green Building Rating System
Author(s): LEED (Leadership in Energy and Environmental Design)
Reference: LEED (Leadership in Energy and Environmental Design)
Publication Organization: US Green Building Council
Publication URL: http://www.usgbc.org/LEED/LEED_main.asp
Abstract: The LEED (Leadership in Energy and Environmental Design) Green Building Rating System™ is a voluntary, consensus-based, national standard for developing high-performance, sustainable buildings. LEED certification assures the tenant that a building reaches high standards of energy performance, while creating comfortable environmental conditions for occupants. Of the 69 credits available for new contrusction within the LEED system, one can be obtained by assuring a minimum of 2% daylight factor over 75% of the floorspace, and another can be obtained by ensuring a direct line of sight to vision glazing from 90% of the floorspace. Similar LEED credits designations are being developed for existing building, commercial interiors, and core and shell projects.
Title: The significance of sunshine and view for office workers
Author(s): Markus, TA
Reference: Markus, T.A., (1967) The significance of sunshine and view for office workers, in R.G. Hopkinson (ed) Sunlight in Buildings, Boewcentrum International: Rotterdam, The Netherlands.
Abstract: In an extensive study, 95% of office occupants preferred daylight to electric lighting. Those nearer to windows were more satisfied with their daylight than those further away, particularly on the lower floors. This effect could be attributable to the view out of the building, or to the amount of daylight. Occupants near the south-east and south-west walls were more satisfied with their daylight than those near the north-west and north-east walls. This may be because they value the availability of direct sunlight, or it may be due to window glare being more severe through north-facing windows. The study surveyed 400 office workers on nine floors of a 12-story open-plan building.
Title: Circadian photobiology: An emerging framework for lighting practice and research
Author(s): Rea, MS, Figueiro, MG, Bullough, JD
Reference: Rea, Mark S., Mariana G. Figueiro, and John D. Bullough. (2002) Circadian Photobiology: an Emerging Framework for Lighting Practice and Research. Lighting Research and Technology 34(3), 177-190.
Abstract: Lighting can be used to strengthen the human circadian rhythm, which determines various physiological functions such as sleep, digestion, alertness, depression, and probably general health. Daylight is much more effective than electric lighting at ‘entraining’ the circadian system; this is because the circadian system responds only to high levels of blue light, such as those found in daylight. Rea et al. calculate ‘circadian efficacies’ for various light sources, and find that daylight is three to four times more effective than fluorescent lamps, and twenty times more effective than incandescent lamps. They find that "light levels approaching those found outdoors in daylight are sufficient for regulation of the circadian clock and the melatonin cycle, but many indoor light levels are too low."
Title: Daylight and productivity - A possible link to circadian regulation
Author(s): Figueiro, MG, Rea, MS, Stevens, RG, Rea, AC
Reference: Figueiro, M.G., Rea, M.S., Stevens, R.G., and Rea, A.C. (2002) Daylight and productivity - a possible link to circadian regulation, Proceedings of the Fifth Intl LRO Lighting Research Symposium, EPRI: Palo Alto, CA.
Abstract: This study found that workers in windowless offices spend a small but statistically significantly greater amount of time talking to others, either directly or by telephone; and a small but statistically significantly lesser amount of time working on their computer, relative to the workers in the windowed offices. It was hypothesized that the people in the windowless offices would not receive sufficient light to entrain their circadian systems and so would seek to entrain them either by seeking out exposure to daylight and consequently spending less time in their offices, or by seeking more social interactions, a factor that can also be used to entrain the circadian system. An alternative explanation for these findings would be that the workers in the windowless offices were seeking additional short-term stimulation, something that was provided by the view out in the windowed offices, and the differences in behavior had nothing to do with the circadian system. Regardless of which explanation is correct, the presence of a window would seem to provide a benefit in terms of desirable behavior at work.
Title: Status in organizations: Where evolutionary theory ranks
Author(s): Waldron, D
Reference: Waldron, D. (1998). Status in Organizations: Where Evolutionary Theory Ranks. Managerial and Decision Economics (19), 505-520.
Abstract: The desire for status is one of the strongest sources of motivation for employees. This paper cites Halloran (1978) in stating that proximity to windows, and the number of windows in an office, is a common and widely understood expression of status. The author does not discuss whether the provision of windows enhances the overall status of a building or a company, or whether the effect exists only within organizations. The author makes a distinction between status and hierarchy: the former being an informal system of signs (“status symbols”) and behaviors; the latter being a more formal organizational structure expressed in job titles and remuneration. Status appears to be a pervasive phenomenon in organizations, as it is in all societies, and may be genetically or instinctually based since it is exhibited by other ape species.
Title: Windows and daylight - A post-occupancy evaluation of offices
Author(s): Christoffersen, J, Petersen, E, Johnsen, K, Valbjorn, O
Reference: Statens Byggeforskningsinstitut. (1999). Report 318: Windows and Daylight - a Post-occupancy Evaluation of Offices. Horsholm, Denmark.
Publication Organization: Statens Byggeforskningsinstitut, Horsholm, Denmark
Abstract: A survey of 2340 Danish office workers found that there is a strong preference for having the workstation close to a window, despite a higher incidence of glare and reflections on PC screens. Occupants' satisfaction with their daylighting was strongly positively correlated with measured daylight factor. Sixty percent of occupants wished to have direct sunlight in their office during at least one season of the year. More than 50% of respondents reported no negative aspects of their windows; of the problems reported, glare was the most frequent, followed by heat discomfort. The degree of dissatisfaction with daylighting increased with the number of people in the office.
Title: Work attitudes in windowed versus windowless environments
Author(s): Finnegan, MC, Solomon, LZ
Reference: Finnegan, M.C., and Solomon, L.Z. (1981) Work attitudes in windowed versus windowless environments, Journal of Social Psychology, 115, 291-292.
Abstract: A study of 123 office workers found that employees in windowed offices were significantly more positive than windowless employees with regard to: job satisfaction (i.e., liking their job); the interest value of their job (i.e., finding the job stimulating); and their physical working conditions. There was no significant difference in employees’ responses regarding sense of time (i.e., whether it passes slowly or quickly); anxiety (i.e., fatigue, tension); or sense of space (i.e. feelings of confinement or isolation).
Title: Window blind occlusion: A pilot study, building and environment
Author(s): Rea, MS
Reference: Rea, M.S., (1984) Window blind occlusion: A pilot study, Building and Environment, 19, 133-137.
Abstract: Building occupants seldom adjust their window blinds during the course of the day; they tend to leave their blinds closed even when glare-free diffuse daylight could be admitted. Window blinds are typically more than 50% occluded. It might be expected that occupants would close blinds to exclude sunlight, and open them again under cloudy skies to admit more daylight, but results suggest that occupants set their blinds to a position in which solar glare is sufficiently excluded under most sky conditions, and leave the blinds in that position for weeks, months or years. 555 window blinds in an office building were monitored using photographs of the façade. The east, south and west facades had an average of 50%, 66% and 62% occlusion respectively. Between cloudy days and sunny days, these occlusions varied up or down from the average by 10%, 1% and 2% respectively. The east façade showed significantly more variation than the other facades, though no explanation for this is offered. These results are similar to results found previously by Rubin.
Title: Enclosure systems
Publication Organization: Northwest Energy Alliance (Better Bricks)
Publication URL: http://www.betterbricks.com/graphics/assets/documents/DesignSystemEnvelopguideline_pa.pdf
Abstract: Discussion of the available options for building enclosure (facade) systems, including external shading devices and internal light shelves. The effect of these systems on visual comfort inside buildings, and upon HVAC systems is discussed. Visual comfort issues include: avoiding excessive contrast and solar glare; maximizing the amount of natural light and visual stimulation. The limitations of light shelves and external shading devices are described, along with the importance of multi-factorial design in producing successful buildings. Differences in local climate are addressed, and a checklist for successful design is provided.
Title: Daylighting and productivity at Lockheed
Author(s): Burke Miller Thayer
Publication Organization: Northwest Energy Efficiency Alliance, reproduced from Solar Today magazine
Publication URL:
Abstract: A report on a daylighting and productivity study conducted in a daylit office building in Sunnyvale, CA, staffed by the Lockheed Martin Company. The report claims, “In the their first year in ‘Building 157’, Lockheed saved half a million dollars on energy bills and several times more due to reduced absenteeism and improved employee productivity.” Lockheed also believes that the building’s effect on morale helped them to win a $1.5bn contract soon after its completion. The report describes specific features of the building, including lightshelves, angled glazing and sloping ceilings.
Title: Effects of interior design on daylight availability in open-plan offices
Author(s): Reinhart, CF
Publication Organization: National Research Council of Canada
Publication URL: http://irc.nrc-cnrc.gc.ca/fulltext/nrcc45374/nrcc45374.pdf
Abstract: An investigation of the daylighting effect of design variables including: blinds, partition height, and ceiling and partition reflectance. The results show that, when complemented by a daylight-linked lighting system, blinds closed at 45 degrees can save up to 26% of lighting energy, manual blinds can save 41%, and automatic blinds 58%; all energy savings are in comparison to full installed load. Peripheral offices can typically save 25%-60% of their lighting energy by daylight-linking, and second-row offices can save 20%-40%. The results were obtained by computer modelling of a south-facing office with ribbon windows and clear glazing, using New York City climatic data.
Title: Tips for daylighting with windows: Envelope and room decisions (pages 3-1 to 3-7)
Author(s): O'Connor, J, Lee, ES, Rubinstein, F, Selkowitz, S
Publication Organization: Lawrence Berkeley National Laboratory
Publication URL: http://windows.lbl.gov/pub/designguide/section3.pdf
Abstract: This guide gives design advice that explores the purpose, positioning, sizing and detailing of windows. Many sketches are used to show a wide range of possible design options, and the consequences of design choices such as glazing transmission, room depth, furniture layout, desk orientation, and light shelves.
Title: Daylight Dividends Case Study
Author(s): Yukio Akashi, Peter Morante
Publication Organization: Lighting Research Center
Publication URL: http://www.daylightdividends.org/pdf/TomoTherapyCaseStudy.pdf
Abstract: This case study is unique in that it involves a tenant-occupied building that the designers and building owner agreed to design to take advantage of daylighting for the TomoTherapy building as a means of improving energy efficiency and helping to ensure occupant comfort.
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Retail
Title: Retail skylighting knowhow
Publication Organization: Design Lights Consortium
Publication URL: http://www.designlights.org/downloads/skylighting_Retail.pdf
Abstract: This guide shows how to use skylights in retail environments to enhance a store''s appearance, attract and retain shoppers, and produce savings on lighting energy costs. The guide is illustrated with sample retail layouts, and describes how skylights can be integrated with electric lighting and lighting controls to maximize energy savings. Estimated energy savings are given for each skylighting option. Systems optimized for the northeastern United States are described in detail, and the guide cites research that finds evidence of increased retail sales in stores with skylights.
Title: Field Test Delta: Integrated Skylight Luminaire
Publication Organization: Lighting Research Center
Publication URL: www.lrc.rpi.edu/programs/delta/pdf/fieldtestdelta.pdf
Abstract: High-bay warehouses, light industrial facilities, and big box retail stores offer the opportunity to save energy and improve occupant satisfaction by admitting daylight through their roofs. Prototypes of an Integrated Skylight Luminaire (ISL) were installed in a working warehouse and analyzed for energy savings and lighting quality. Each ISL includes a skylight, fluorescent luminaires, and a self-commissioning control system that automatically dims or switches the lamps in response to daylight. The ISL’s design and field performance are documented. Use of the ISL was shown to reduce energy consumption by up to 40%.
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Schools
Title: Patterns to Daylight Schools for People and Sustainability 
Authors: Russell Leslie, Aaron Smith, Leora Radetsky, Mariana Figueiro, and Lisa Yue
Publication URL: /programs/daylighting/pdf/DaylightingPatternBook_Final.pdf
Description: The latest pattern book by LRC authors, sponsored by the US Green Building Council, presents model designs for implementing daylighting into school classrooms, corridors, and gymnasiums. With emphasis on human health impact and other daylight metrics, this book compares cost, comfort, visual environment, and energy use among well-known daylighting techniques.
Title: Classroom lighting knowhow
Publication Organization: Design Lights Consortium
Publication URL: http://www.designlights.org/downloads/classroom_guide.pdf
Abstract: This guide provides some advice on how to use photocell dimming in schools to save lighting energy without creating distraction to students. It also provides guidance on what types of luminaries to use, and how best to orient and group them in order to maximize energy savings. Estimated energy savings are given for a variety of luminaire and control options. The guide intends to "promote high-quality learning among children … via the utilization of energy-efficient applications such as daylighting and lighting controls." (Ref: http://www.designlights.org/downloads/classroom_guide.pdf). To this end it cites research which claims that students in well daylit schools score better in exams than those in poorly daylit schools.
Title: Daylighting in schools
Author(s): Heschong Mahone Group
Publication Organization: Pacific Gas and Electric
Publication URL: http://www.pge.com/includes/docs/pdfs/shared/edusafety/training/pec/daylight/SchoolDetailed820App.pdf
Abstract: A report on a study into the relationship between daylighting and human performance. The report contains an executive summary and detailed descriptions of the research methods and results of a study which found that students in "daylit" classrooms progressed around 20% faster in all subjects, than those in non-daylit classrooms. The results are based on the examination grades of over 21,000 elementary school students in California, Washington and Colorado. The study attempts to separate the effect of daylight illumination from other benefits such as views out of the building. The authors claim that the climatic diversity of the schools studied, the diversity of their teaching styles and architectural design, and the results of a companion study into retail sales suggest that "these performance benefits from daylighting can be translated into other building types and human activities." It should be noted that the quality of daylighting explained only 0.3% of the variance of students' performance, although this figure is comparable with other factors which are widely believed to be influential, such as number of absences (0.1%), the size of the school (0.1%) and participation in extra classes (0.3%).
Title: Smith Middle School
Publication URL: /programs/daylighting/pdf/SmithCaseStudyFinal.pdf
Abstract: In 2001, the Smith Middle School opened its doors, embracing not only a new student body, but also an environmentally conscious attitude. Part of the Chapel Hill-Carrboro City School District in Chapel Hill, North Carolina, the Smith Middle School exemplifies good daylighting design practice. This case study documents that good daylighting design incorporated at a building's inception yields positive results in energy savings, comfort and a reasonable return on the added investment.
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Warehousing
Title: Skylighting Guidelines (Chapter 8)
Publication Organization: Heschong Mahone Group, for the Northwest Energy Efficiency Alliance
Publication URL:
Abstract: This report gives practical design guidance on the use of skylights. It gives numerical information on illumination patterns and likely energy savings by region, glazing type, building type and control type, all presented in graphical form. This report is targeted towards designers and building owners in four Pacific-Northwest states: Oregon, Washington, Idaho and Montana. It reviews the climate of the region, differing energy-code requirements in the separate states, and common building practices that affect the specification of skylights for commercial buildings.
Title: Warehouse skylighting knowhow
Publication Organization: Design Lights Consortium
Publication URL: http://www.designlights.org/downloads/skylighting_Warehouse.pdf
Abstract: This guide shows in detail how to design skylights and daylight—linked controls in warehouses to increase energy cost savings, productivity, and worker safety while reducing maintenance costs. The guide shows how to analyze skylight designs using software such as “SkyCalc” and it gives estimated energy savings for a variety of design options. It compares the performance of metal halide and fluorescent lamps, provides illustrated equipment layouts, and addresses construction concerns.
Title: Field Test Delta: Integrated Skylight Luminaire
Publication Organization: Lighting Research Center
Publication URL: www.lrc.rpi.edu/programs/delta/pdf/fieldtestdelta.pdf
Abstract: High-bay warehouses, light industrial facilities, and big box retail stores offer the opportunity to save energy and improve occupant satisfaction by admitting daylight through their roofs. Prototypes of an Integrated Skylight Luminaire (ISL) were installed in a working warehouse and analyzed for energy savings and lighting quality. Each ISL includes a skylight, fluorescent luminaires, and a self-commissioning control system that automatically dims or switches the lamps in response to daylight. The ISL’s design and field performance are documented. Use of the ISL was shown to reduce energy consumption by up to 40%.
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