Reports & Publications - Other Reports

Daylighting Lab Operation and Management Plan

Seed Research Proposals

Sponsors of the Daylight Dividends program, through the Lighting Research Center, solicit proposals and extend grants to examine, develop, evaluate and analyze daylighting issues raised by non-residential building owners and designers. These proposals seek to address the program's two identified focus areas: to clarify the benefits of daylighting, and to advance the technological components required to achieve these benefits. Four such proposals have been selected for seed research this year.

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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A Working Plan to Develop a Daylighting Lab and Outreach Center
University of Idaho
Principal Contact: Kevin Van Den Wymelenberg, M. Arch., Assistant Professor

This project will document the BetterBricks Daylighting Labs of the Pacific Northwest, a nationally recognized working plan for regional daylighting lab operation and design. A report outlining the business models of the Pacific Northwest Labs will serve as a blueprint for those public or private entities seeking to develop and operate a local daylighting resource center. The project convenes a team of nationally recognized daylighting experts to review and critique the work of the BetterBricks Labs. This review will be summarized and will form the foundation for the documentation of the BetterBricks Daylighting Lab Network's development and operation. The project report will articulate a step-by-step process to develop collaborations and implement services with the mission of transforming regional market demand for high-value, high-performance building designs that are founded on daylighting design.

The Relationship Between View Quality and Employees' Sick Leave in Work Environments
University of Oregon
Principal Contact: Ihab Elzeyardi, Ph.D., Assistant Professor

The proposed study investigates the relationship between daylight quality and health on office workers. It also attempts to place a value on daylighting in the workplace by linking its degree of availability to sick leave days taken by office workers. The research will employ a cross-sectional survey design to assess daylighting availability in offices, daylighting quality, as well as other parameters of the physical environment and their attempts to investigate the relationship between sick leave and absenteeism. In addition, the study attempts to investigate the relationship between sick leave and the quality/type of views from windows. The objective here is to address and quantify a long debated hypothesis regarding the importance non-residential building occupants place on the need to be in contact with nature and the outdoors (the biophilia hypothesis) while working within a building.

Distilling Daylighting Knowledge into Place-Specific, Instantly Available, Provocative Tools
University of Oregon
Principal Contact: G. Z. Brown, Professor and Director of Energy Studies in Buildings Laboratory

This project will create daylighting design tools that are dramatically simpler to use and quicker to learn than existing tools, and are oriented to creating rather than analyzing daylight-revealed spaces. This will be accomplished with a computer-based system that distills project information (climate, site, use, design), and generates a customized tool that can be printed and overlaid on the design drawing to reveal daylit spaces within the building. Delivery of the computerized results can be instantly transmitted via the web.

How Much Energy do Different Sidelighting Strategies Save
Pennsylvania State University
Principal Contact: Martin Moeck, Ph.D., Assistant Professor

This research proposal develops a series of case studies for different windows using state-of-the-art lighting and building energy analysis software. These case studies include commercially available, common glazing and shading types in tabular format. The quick lookup table will list the yearly performance of different shading strategies and different vertical window sizes and orientations for different climates across the U.S. The tool will allow architects and building owners to select the best strategies with the highest yearly net energy savings for a specific climate and save time for the design team by steering them in the right direction. Problematic solutions will also be visible in the tabular format.

How much energy do different toplighting strategies save?
Pennsylvania State University
Principal contact: Martin Moeck, Ph.D., Assistant Professor
Based on a series of case studies, this project develops a tabular tool "that shows building owners, designers and contractors which top lighting strategies and which glazing characteristics lead to a maximum yearly net energy gain for a particular climate zone."

Quantification of the value of windows and views to indoor occupants
University of Michigan, Taubman College of Architecture + Urban Planning
Principal contact: Jong Jin-Kim, Ph.D., Associate Professor

A study has been proposed to "quantify and document the financial and psychological values of windows and outdoor view to indoor occupants in commercial buildings." The study will present correlation between the views and rental incomes from 15 rental office buildings in New York, Los Angeles, and Chicago. In addition, the study will also investigate the occupant's seating preference with regard to windows and views. An analysis of the work performance of occupants in perimeter spaces with a view and interior spaces without a view will also be presented.

Identifying and correcting the barriers to daylighting in schools
North Carolina Solar Center, North Carolina State University
Principal contact: Herbert M. Eckerlin, Ph.D, Professor

The submitted proposal "seeks (1) to identify the barriers to the acceptance of daylighting in schools, (2) to identify and implement strategies for overcoming these barriers, (3) to quantify the energy savings resulting from the wider utilization of daylighting in schools, and (4) to develop and present workshops that educate teachers and administrators how to properly utilize daylighting to save energy while simultaneously improving the teaching environment."

Manually Activated Pneumatic Shade Control
Energy Studies in Buildings Laboratory, University of Oregon
Principal Contact: G.Z. Brown, Professor

Daylighting can be a useful strategy for reducing electric use. However, in order for this strategy to be effective, its adverse effects such as glare and heat gain/loss must be minimized. Electric lighting must be turned off or dimmed in response to the daylight available to actually realize the energy benefits of daylighting. One of the most common and inexpensive methods to avoid the visual discomfort of a window designed to increase daylight penetration, is by using venation blinds. Unfortunately while people can be expected to close the shades when they are uncomfortable, they don't often re-open them in a timely manner to capture the daylight needed to reduce the electric lighting. This project develops a low cost venetian shade control that reopens the blind and is powered by the action of the user shutting the blind.