Architects' Perceptions of LEED Indoor Environmental Quality Checklist Items on Employee Productivity

Abstract

Leadership in Energy and Environmental Design (LEED) certification and the application of associated design checklists are becoming increasingly common in contemporary building design and construction. At the time of the study, the United States Green Building Council's (USGBC) website stated that, from 2001 to 2003, there was a 467% increase in USGBC membership, a 162% increase in certification, and a 77% increase in registered projects. The website also noted that approximately 12% of new commercial spaces were LEED certified (USGBC, 2002). Research literature reports that most employees spend 80% of their day indoors and that the indoor environment may be up to 10 times more polluted than outdoor air. Indoor Environmental Quality (IEQ), therefore, may directly affect a person's health and productivity. Despite the potential impact of poor IEQ on employees, few studies have been able to make a direct association between specific IEQ items and their impact on productivity. This study reviews of each of the 17 components that comprise the LEED IEQ checklist and investigates architects' perceptions of checklist components on employee productivity. Although this study was based on the LEED Version 2.1, the components of the current New Construction Version 2.2 (2005) are essentially the same.

Keywords:

• indoor air quality
• indoor environmental quality
• LEED
• productivity
• USGBC

Introduction and Background

Many studies have indicated that poor indoor environmental quality (IEQ) has a negative affect on employee health and productivity (“Germguard”, 2002; Heerwagen, 2002; Medallion healthy air, 2002; Office IAQ and productivity, 1999; Pearson, 2002; Solberg, 1999). Each year, millions of work hours are lost due to minor symptoms, such as headaches, nausea, fatigue, and eye irritation. Most often the cause is unknown, but the literature suggested a possible connection between indoor environmental quality and these symptoms. According to Pearson (2002), if health is affected by poor indoor environmental quality, then it is likely that increased health related absences would cause productivity at work to decrease. Haymore and Odom (1993) noted that productivity gains and associated cost saving from improved IEQ are unlikely to occur until employees who work in those environments demand improvements.

Building owners have often been reluctant to have their buildings studied, fearing that if something were detected, they could be held accountable for housing employees in unsafe environmental conditions (Heerwagen 2002). What these owners may not realize is that by ignoring what the literature suggests, they could lose large amounts of money every year on employee productivity alone. In addition, if the owners of buildings continue to ignore the signs of an unsafe environment, they could spend additional money on potential lawsuits (Bearg, 1998; Haymore & Odom, 1993; Heerwagen, 2002).

Furthermore, building owners are simply not aware of the large amounts of money that can be saved by creating quality indoor working environments (Haymore & Odom, 1993). Building occupants often do not demand quality indoor environments when choosing office spaces, so building owners have little incentive to invest in them. Most owners tend to invest more in building appearance than in the environmental mechanics of a building, because that is what people see; so too little attention is paid to the functional aspects of a building. As building owners become more aware of how much money can be saved by having quality indoor environments, purchasing decisions will begin to change.

The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), along with other organizations, is working together to increase the pace of research on IEQ. Leadership of Energy and Environmental Design (LEED) Green Building Rating System is promoted by the United States Green Building Council (USGBC 2002) to provide a national standard for green building. LEED tools, designed by the USGBC, were developed to help design teams and owners determine green project goals, identify green design strategies, measure and monitor progress, and document project success. There are six total sections of the LEED Green Building Rating System: (a) Sustainable Sites, (b) Water Efficiency, (c) Energy & Atmosphere, (d) Materials & Resources, (e) Indoor Environmental Quality, and (f) Innovation & Design Process.

This study investigated Indoor Environmental Quality. This section is divided into 10 categories: (a) Minimum Indoor Air Quality Performance, (b) Environmental Tobacco Smoke Control, (c) Carbon Dioxide Monitoring, (d) Ventilation Effectiveness, (e) Construction Indoor Air Quality Management Plan, (f) Low-Emitting Materials, (g) Indoor Chemical and Pollutant Source Control, (h) Controllability of Systems, (i) Thermal Comfort, and (j) Daylight and Views. To be LEED-certified, a project must earn certain number of points from the six LEED sections. The level of certification depends on the total number of points that are obtained from the checklists for each section. There are four possible levels of certification: (a) Certified, 26 to 32 points, (b) Silver, 33 to 38 points, (c) Gold 39 to 51 points, and (d) Platinum 52 to 69 points.

For the purpose of this study, the IEQ checklist items were used to identify which items are perceived to be most closely linked to employee productivity, and which items are perceived to have the greatest employee productivity gain for the initial cost. The results allow building owners to have a better understanding of which items are believed to provide the greatest return on investment while also improving employee productivity.

USGBC and LEED

When building owners hear the words “green design,” it is natural for them to think of higher costs. However, throughout the past decade the term itself has become more commonly understood and overall costs of green buildings have begun to decrease. Heinfeld (2003) speculated that owners believe green buildings are prototypical and too expensive for ‘real world’ budgets. However, many features of sustainability and enhanced IEQ may be achieved at little cost if incorporated into the original design. Heinfield (2003) went on to state that, through the overall life-cycle of a building, owners not only make their money back, but can also make a profit on green investments. Indeed, while estimates vary substantially, many authors reported that failure to address IEQ issues is estimated to cost building owners in the United States billions of dollars annually (Bad Air We Breath, 2001; Fisk, 2002; “Germguard”, 2002; Medallion Healthy Air of Texas, 2002; Monroe, 2002). Heerwagen (2002), a behavioral ecologist who studies buildings as habitats, concluded that highly productive building must be green building.

Lewis (2002) noted that one of the most effective ways to ensure that a building has been designed and constructed to meet certain green building standards is the LEED rating system. In addition, Lewis stated that LEED-certified buildings signify environmental leadership. LEED certification of new facilities by non-for-profit organizations has become an effective strategy for fund-raising because of the appeal to the environmentally aware donor. Although there are other systems (such as Balanced Score Card, developed by Kaplan and Norton in 1996), the LEED rating system can guarantee many benefits that cannot be accomplished with any other system (Heerwagen, July 2002). According to Lewis, the benefits associated with the LEED rating system are: (a) that it reassures the building tenants or occupants that they are getting appropriate IEQ, (b) that the documentation of the designed features are actually installed and operating as intended in the construction contract, and (c) that many state and local programs are starting to provide benefits to LEED-certified projects (grants, tax credits, expected permitting processes, or exemption from specific zoning restrictions are some of the specific benefits that these programs provide).

Green design and LEED certification go hand-in-hand when trying to build quality indoor environments. Consequently, LEED is becoming recognized around the world and is having an affect on architectural decision making. More architects are becoming aware of the problems associated with poor IEQ and the affects it has on building occupant's health, well-being, and productivity. As a result, decision-makers increasingly depend on the knowledge of the architects to make the best choices concerning IEQ.

LEED and the Indoor Environmental Quality Checklist Items

The following section reviews research related to each of the components of the LEED IEQ checklist with emphasis on the potential to contribute enhanced employee productivity.

Minimum Indoor Air Quality Performance

The Environmental Protection Agency (EPA) puts indoor air quality (IAQ) issues at the top of the list when ranking the United States' most urgent environmental issues (Haymore & Odom, 1993; Medallion healthy air, 2002). The EPA estimated that indoor air pollution either causes or exacerbates up to 50% of all illness. (Medallion healthy air, 2002). Similarly, research in the United States indicated that close to 60% of people have been affected by poor IAQ that could ultimately lead to higher employee absentee rates (“Germguard”, 2002). Pearson (2002) inferred that if health is affected by poor IAQ, then it is likely that sickness related absences increase, causing productivity at work to decrease.

While research cited above has linked poor IEQ to an increase in illness, estimates vary considerably as to how this translates into lost productivity costs. Haymore and Odom (1993) estimated that lost employee productivity is costing the United States $41.4 billion annually. Solberg (1999) reported a 1997 study by the U.S. Department of Energy and Lawrence Berkeley National Laboratory that estimated that between $12 to $125 billion was lost annually from reduced employee productivity. ASHRAE reported an annual loss to American business of nearly $60 billion resulting from decreased productivity associated with poor IEQ. (Office IAQ and productivity, 1999).

On the other hand, several studies showed that a good IAQ could improve employee productivity (Fisk, 2002; Heerwagen, 2002; Indoor air study, 1993; Pearson, 2002). CenterCore Inc., a manufacturer of interior environments, conducted a baseline case study on IAQ and employee productivity. The study was based on sickness records provided by the owner and suggested that when there was a 94% increase on improved air quality, there was a 40% self-reported increase in productivity of employees (Indoor air study, 1993). In addition, Pearson (2002) reported that productivity can increase by 6% to 7% when air quality is improved. Consistent with these findings, Fisk (2002) reported that better IAQ promotes employee productivity, which has the potential to saves employers between $20 billion and $160 billion.

The large range of costs or savings related to IEQ issues is due to the difficulties associated with doing research on productivity. Because productivity is problematic to address directly, it has been difficult to quantify precisely in past research. As a result, few research studies have been able to identify specific items in the interior environment that are highly associated with employee productivity gains.

Numerous studies (Fisk, 2002; Heerwagen, 2002; Monroe, 2002; Solberg, 1999) have emphasized the importance of improving IAQ to building architects, designers, owners, and occupants. Spicer (1997) estimated that 50% to 70% of IAQ problems are linked to the design, operation, and/or maintenance of the building HVAC system. The productivity loss estimates in the studies reported and the connection to HVAC systems should be wake-up call to companies and building owners.

The intent of the IAQ section in the LEED Green Building Rating System (2002) is to “Establish minimum indoor air quality performance to prevent the development of indoor air quality problems in buildings, thus contributing to the comfort and well-being of the occupants” (p. 47). The specifications of this section involve meeting the minimum requirements of American Society of Heating, Refrigerating, and Air-Conditioning (ASHRAE) 62-1999, Ventilation for Acceptable Indoor Air Quality. LEED recommended identifying potential IAQ problem areas. In addition, LEED also recommended locating the air intakes away from contaminant sources (USGBC, p. 47). Many of the components in the LEED Green Building Rating System have an effect on IAQ, and will be discussed in the following sections.

Environmental Tobacco Smoke (ETS) Control

ETS contain a complex mixture of over 4,000 chemical compounds that have the potential to affect a majority of adults. Respiratory irritants such as sulfur dioxide, ammonia, formaldehyde, and acrolein are some of the compounds included in the mixture (Eisner, 2002). The EPA has designated ETS as a Class A carcinogen, placing it in the same category as asbestos, benzene, and radon, all of which are harmful to human health. It is estimated that ETS is responsible for 53,000 annual deaths in the United States, which is more deaths than auto accidents or AIDS (Glantz & Parmley, 1991).

Numerous research reports have documented the relationship between ETS and impaired respiratory function, coronary heart disease, lung cancer and reduced breathing capacity (Eisner, 2002; Mendell, et. al., 2002; Mizoue, Ueda, Hino, Yoshirmura, 1999). As a result, numerous public and private building owners have implemented restrictions or total ban against smoking to protect nonsmokers from ETS.

The intent of the LEED rating system (2002) is to prevent building occupants and systems from ETS exposure. Two options are available to receive points on the rating system for zero exposure of non-smokers to ETS: (a) prohibiting smoke in the building, or (b) providing a designated smoking room designed to contain capture and remove ETS from the building.

Carbon Dioxide Monitoring

Haghighat and Donnini (1993) concluded that carbon dioxide (CO₂) is the ideal indicator for IAQ. CO₂ monitoring in ventilation systems are becoming more frequent in buildings in the United States as a way to improve occupant health and productivity. Bearg (1998) recommended that in an adequate building ventilation system would daily purge the structure of accumulated air contaminates and reduce the indoor CO₂ concentrations levels to those consistent with outdoor levels. Bearg also noted that CO₂ monitoring alone does not guarantee good IAQ, but it is a necessary component of a successful indoor air quality program.

The LEED Green Building Rating System's (2002) intent for CO₂ monitoring is to “provide capacity for indoor air quality monitoring to help sustain long-term occupant comfort and well-being” (p. 50). The LEED rating system requires a permanent CO₂ monitoring system that provides feedback on space ventilation performance in a form that affords operational adjustments. LEED suggested designing the HVAC system with CO₂ monitoring sensors and integrating the sensors with the building automation system.

Ventilation Effectiveness

Ventilation systems in commercial buildings supply outdoor air to replace the oxygen consumed and to dilute air contaminants created by occupants and their daily activities. Mendell and Coworkers (2002) found that symptoms associated with poor IAQ are reported more frequently in buildings with inadequate ventilation systems, which ultimately impairs an occupant's health and performance. In addition, the National Institute on Safety and Health found that 53% of reported cases of sick building syndrome are due to inadequate air ventilation. Indicators of sick building syndrome are eye irritation, headaches, and upper and lower respiratory ailments that are estimated cost U.S. employers $20 to $70 billion annually (Mendell et al., 2002).

A host of studies indicated that inadequate ventilation systems negatively affect employee health, well-being, and productivity (Bearg, 1998; Fisk, 2002; Hedge et al., 1993; Kumar & Fisk, 2002; Mendell et al., 2002; Solberg, 1999). Respiratory illness is one of the major symptoms of an inadequate ventilation system. Fisk (2002) reported a 35% reduction in respiratory illnesses in buildings with higher ventilation rates. Consequently, the productivity gains estimated for decreasing respiratory illness alone were between $6 to $14 billion. The National Contractors Study's review of 500 studies revealed that if ventilation was improved by 2%, the return on investment for productivity alone would be $6.50 per square foot annually (Solberg, 1999).

To earn LEED points for effective ventilation (USGBC, 2002), the system must deliver and mix fresh air to support the safety, comfort, and well-being of building occupants. Specifically, mechanically ventilated buildings must demonstrate air change effectiveness ≥ 0.9, as determined by ASHRAE 129–1997. Naturally ventilated spaces are required to exhibit a “distribution and laminar flow pattern that involves not less than 90% of the room or zone area in the direction of air flow for at least 95% of hours of occupancy” (p. 51). For optimal ventilation results, LEED suggested that: (a) displacement ventilation or, low-velocity ventilation, (b) plug-flow ventilation such as under floor or near floor delivery, and (c) operable windows. LEED also suggested testing the air change effectiveness of the building after construction.

Construction IAQ Management Plan, During Construction, and Before Occupancy

The design, material and contents of a building are all factors that effect the indoor environment. Mendell and Colleagues (2002) found that the following building practices impact the indoor environment and occupant health: “(a) construction, commissioning, operation, maintenance, renovation, and repair of the building and ventilation system; (b) selection of materials in buildings and ventilation systems; and (c) protection of occupants from contaminants produced during construction and renovation” (p. 1435).The intent of the LEED Construction IAQ Management Plan during construction is to maintain adequate air quality and hence the health and comfort of construction workers and building occupants, if during renovations (USGBC, 2002).

The LEED construction IAQ management plan (USGBC, 2002) must address all of the following requirements:

1. meet or exceed the recommended design approaches of the Sheet Metal and Air Conditioning National Contractors Association IAQ Guideline for Occupied Buildings under Construction, 1995 (Chapter 3);

2. provide on-site protection for material from moisture damage;

3. when using air handlers during construction, filtration media with a minimum efficiency reporting value of eight must be used at all return air grills; and

4. all filtration media must be replaced prior to occupancy.

It is also essential to consider the potential IAQ hazards that are associated with construction. Some specific examples are keeping ETS out of the building no matter the phase of construction, protection of materials from moisture and keeping IAQ levels comfortable for current occupants during renovation. To this end, it is critical to develop and implement an IAQ Management Plan that concentrates on the time before occupancy. The IAQ Management Plan should include a 2-week minimum flush-out or a baseline IAQ test following EPA standards.

Low-Emitting Materials

Heerwagen (2002), an environmental psychologist who has done extensive research on IEQ and its effect on productivity, concluded that human beings must be the starting point for design. A building occupant would be less concerned with the aesthetics of their workplace, if he/she knew about the harmful toxins that most materials release. Many carpets, paints, adhesives, and other interior products emit extremely harmful volatile organic compounds (VOC's) such as formaldehyde that can be damaging to those directly in the area. Other sources of VOC's include ventilation systems, irritating aerosols, cleaning products, new computers, photocopiers, printers, and fresh paint. The symptoms normally associated with VOC emissions are similar to those associated with sick building syndrome (Mendell et al., 2002).

The intent of the LEED standard related to low-emitting materials is to reduce indoor air pollutants and thereby to improve the health and safety of occupants and interior finish installers. For adhesives and sealants, LEED requires that the VOC content must be less than the current VOC content limits of South Coast Air Quality Management District Rule #1168. LEED also requires all sealants that are used as fillers meet or exceed the requirements of the Bay Area Air Quality Management District Regulation 8, Rule 51. In the paints and coating section, LEED specifies that all VOC emissions from paints and coatings should not exceed the VOC and chemical component limits of Green Seals' Standard GS-11 requirements. Carpet requirements include meeting or exceeding the requirements of the Carpet and Rug Institute's Green Label Indoor Air Quality Test Program. The last item of the Low-Emitting Materials section specifies that composite wood cannot contain any added urea-formaldehyde resins (USGBC, 2002). The benefits from designing spaces that implement low emitting materials are significant and should not have a detrimental affect on the overall appearance of the structure.

Indoor Chemical & Pollutant Source Control

The Medallion Healthy Air of Texas (2002) reported that more than 3,000 pollutants contribute to the problem of contaminated indoor air. The EPA acknowledged that the indoor air may be two to three times more contaminated than the outdoor air and that poor IAQ may cause or aggravate up to 50% of all illness. Indoor air pollution originates from a variety of sources such as contaminated outdoor air, contamination arising from air-conditioning and ventilation systems (such as Legionnaires disease), furniture and interior finish material off-gasing, work activities, and the occupants themselves. Some of the immediate affects of contaminated air include eye, nose, and throat irritation, headaches, dizziness, and fatigue. Controlling the quantity of indoor chemical and pollutant sources is essential to improving IAQ and provides occupants with a healthier environment, reducing illness and improving productivity that ultimately saves money (Medallion et al., 2002). Of further concern to building owners and employers is that building occupants who experience poor health from working in a contaminated environment are increasingly seeking legal remedies (Bearg, 1998; Haymore & Odom, 1993; Heerwagen, 2002).

Strategies to comply with the LEED rating system (USGBC, 2002) must minimize pollutant cross-contamination. Design requirements include: (a) designating a permanent entryway system, (b) where chemicals are used, providing a separate area with deck to deck partitions, and an outside exhaust, and (c) providing drains that are appropriate for the disposal of liquid waste. By meeting the LEED requirements, air pollution will decrease causing IAQ to increase, which leads to a more comfortable and productive work environment for building occupants.

Controllability of Systems

A traditional ventilation system supplies conditioned air into office spaces through ceiling diffusers and removes stale air with ceiling extracts. Hedge, Michael, and Parmelee (1993) explored the benefits of a “task ventilation approach” where raised floor ventilation supplies conditioned air to each workspace at floor level. This alternative allows individuals to have control of airflow and temperatures in their own workspaces. Of the 151 occupants surveyed, Hedge and Colleagues (1993) found that almost two-thirds of the workers agreed that the task ventilation system provided better ventilation and temperature control to support productivity. Studies by Fisk (2002); Heerwagen (2002); and Monroe (2002) indicated similar results associated with personal control of ventilation, temperature and lighting systems. Monroe reported that increased individual control of the workplace was one of the major contributors to productivity.

The Controllability of Systems section of the LEED Green Building Rating System is separated into two parts, perimeter spaces and non-perimeter spaces, with the intent of providing individual occupants or groups with a greater control of thermal, ventilation and lighting systems. (USGBC, 2002). Standards address the need for operable windows and lighting control zones within 15 feet of the building perimeter. LEED also specifies that in non-perimeter spaces, at least 50% of occupants should be provided with controls for individual airflow, temperature, and lighting. Some of the design strategies suggested by LEED include task lighting and underfloor HVAC systems with individual diffusers.

Thermal Comfort

Olesen (2000) divided thermal comfort into two categories: general and local comfort. General thermal environmental parameters included of temperature, humidity, and air velocity. Personal parameters included clothing and activity level. Outside temperature has an effect on general thermal comfort because it affects the clothing that people wear. Temperature ranges should be adjusted according to occupant clothing and activity levels.

Local thermal comfort is expressed by draft, vertical air temperature differences, radiant temperature asymmetry, and surface temperature of the floor (Olesen, 2000). The unwanted heating or cooling of a specific body part often causes thermal dissatisfaction. Fisk (2002) reported that temperature difference may impact the speed or accuracy of workers in tasks such as typewriting and reading speed by 2% to 20%. Other studies also linked an occupant's performance to thermal comfort (Fisk, 2002; Hedge, et al., 1993; Heerwagen, 2002; Olesen, 2000).

To receive credit for this checklist item, thermal comfort must comply with ASHRAE Standard 55–1992, Addenda 1995, for thermal comfort standards including humidity control. Another aspect of the thermal comfort rating system is to provide a permanent temperature and humidity monitoring system.

Daylight and Views

Daylighting allows buildings to benefit from sunlight. When done properly, it creates interesting and dynamic interiors that support occupant health, performance, and activities, while reducing energy demands (Fisk, 2002; Leslie, 2002; Monroe, 2002). Although potential energy savings are a major benefit of daylighting, Leslie reported that the strongest impact of daylighting is on building occupants. A worker's improved productivity, increased job satisfaction, and reduced absenteeism as a result of daylighting is a strong financial argument because all of these employee improvements can easily offset the initial daylighting investment. Leslie (2003) explained that improved occupant performance is due to “levels of melatonin, the hormone responsible for regulating the body's internal clock or rhythm, are influenced by exposure to light levels of the typical day” (p. 382).

Daylighting and views are intended to provide building occupants with a link between the indoor environment and the outdoors. (USGBC, 2002). There are two daylighting sections: (1) daylight for 75% of spaces and (2) views for 90% of spaces. To meet the requirements of the first section, a minimum daylight factor of 2% in 75% of all spaces occupied must be provided. In the second section, a direct line of sight in 90% of all regularly occupied spaces should be implemented. Some of the strategies that LEED suggested are considering building orientation, increased building perimeter, exterior and interior permanent shading devices, and maximum view opportunities.

Linking Specific LEED IEQ Items to Productivity

The foregoing section illustrated that there is an ample research base to support the design components and concepts that comprise the LEED IEQ checklist and to link employee health, comfort, and well-being to productivity. Although research and common sense indicate that employee productivity is impaired by absenteeism and health issues arising from indoor environments, it has been hard for researchers to produce quantifiable data on productivity because worker performance is difficult to define and measure. The result has been widely varying estimates of productivity loss attributable to building environments.

Moreover, few research studies have been able to identify specific items in the interior environment that are most associated with employee productivity gains. Building owners, therefore, have received little information that would justify increased investment in improved building interior environments. One way to get at the relationship between specific items in the IEQ checklist and employee productivity is to survey architects to discover what they have learned from the experience of building LEED registered commercial environments. Therefore, the following study was designed to provide guidance to LEED professionals, architects, and designers, who work with key stakeholders, as to which LEED checklist items experienced architects perceive are most related to employee productivity and which items may be compromised to fit within project budgets.

Methodology

The purpose of this study was to solicit the perceptions of architects who have designed LEED registered commercial spaces to ascertain which items of the IEQ checklist were perceived to be highly linked to employee productivity and which would provide the greatest gain in employee productivity for the initial cost. Given the exploratory nature of this research, a descriptive study was utilized.

In March 2004, there were approximately 900 LEED registered projects. Because the focus of the research was on employees who primarily worked in office environments, only the 330 commercial projects listed were addressed in this study. The architects who designed these projects defined the population. A convenience sample was taken from the population of registered architects using information provided on the LEED website. The sample comprised the 180 architects from the population of 330 who provided their email addresses on the USGBC LEED website. An email message was sent to the sample of 180 architects to solicit their participation in the study and direct them to the research website. The study yielded 55 usable responses, for a total return rate of 31% (55 of 180).

A website was designed for the researcher to provide information to participants about the study and to administer the survey and collect the data. The survey was based on the 17 IEQ checklist items from the LEED 2.1 Green Building Rating System (revised, March 2003). The survey consisted of three parts. Utilizing a 5-point Likert-type scale, the first part asked respondents to rate each of the 17 IEQ items as to there perceived impact on employee productivity. The second part revisited the same 17 items and, again utilizing a 5-point Likert-type scale, asked respondents to rate the degree to which perceived employee productivity gains were worth the money spent. The final section included four short answer questions related to the size and primary use of the registered commercial structure. Respondents were not asked to reveal any personal information and were only contacted through their e-mail addresses.

Data analysis included rank ordering the IEQ items based on the frequency of response. The rating frequencies yielded two lists that ranked architects' perceptions of which items on the IEQ checklist were most associated with employee productivity, and which items were perceived as providing the greatest gains in employee productivity for the initial cost. A quadrant analysis was prepared to graph the relationship between the two sets of data and to make results easier to visualize. The grand mean was calculated for each set of the 17 checklist items and served as the dividing line between quadrants (see the results section for more explanation of this procedure). The short-answer questions were analyzed by frequency of response.

Findings

The participants of the registered commercial projects for this study represent designers of over 10 million square feet of commercial space. The main reason for adoption of LEED criteria for the majority of the participants were stewardship of the environment and owner requirement of implementing LEED practices. The majority of the participants reported that less than 25% of their projects implement LEED principles. Lastly, respondents were asked to identify which of the six LEED checklist areas were most important to their client. The results of this question in rank order based on response frequency were: (a) Energy and Atmosphere (n = 26), (b) Indoor Environmental Quality (n = 16), (c) Materials and Resources (n = 6), (d) Sustainable Sites (n = 3), (e) Water Efficiency (n = 2), and (f) Innovation and Design Process (n = 2).

Item Ranks

The IEQ checklist items were ranked from highest to lowest based on the item response frequency and mean scores to identify the LEED components most associated with employee productivity, and which items were perceived to provide the greatest employee productivity gains for the initial cost.

IEQ Items from Most Associated with Productivity

After the frequency table was developed, a rank of the items was derived using the means from research question one (see Table 1). The item with the highest mean was ranked first, and the lowest mean was ranked last. The rank table indicated that none of the items means were lower than 2.47. “Daylight” and “Views” were the two highest ranked items for question one with only 0.22 difference between the two means. The remaining items were all ranked relatively close to one another. The difference between the means of the item ranked third and the item ranked 15 was only 0.71. This indicated that the items ranked between the top two items and the bottom three items were all considered to be of similar importance to employee productivity.

Table 1 Rank of the IEQ items from most associated with productivity to least associated with employee productivity (research question 1)

Rank	Mean	LEED item number	Item
1	4.37	16	Daylight and views, daylight for 75% of spaces
2	4.15	17	Daylight and views, views for 90% of spaces
3	4.00	14	Controllability of systems, perimeter
4	4.00	12	Thermal comfort, comply with ASHRAE 55-1992
5	3.98	4	Ventilation effectiveness
6	3.95	8	Low-emitting materials, paints
7	3.95	9	Low-emitting materials, carpet
8	3.85	7	Low-emitting materials, adhesives & sealants
9	3.81	15	Controllability of systems, non-perimeter
10	3.71	2	Environmental tobacco smoke control
11	3.53	1	Minimum IAQ performance
12	3.35	10	Low-emitting materials, composite wood
13	3.33	13	Thermal comfort, permanent monitoring system
14	3.29	11	Indoor chemical & pollutant source control
15	2.94	6	Construction IAQ management plan, before occupancy
16	2.87	3	Carbon dioxide monitoring
17	2.47	5	Construction IAQ management plan, during construction

Gain in Employee Productivity for the Initial Cost

The rank table for research question two indicated that all of the items except for carbon dioxide Monitoring were rated to have a high gain in employee productivity for the initial budgeted cost (see Table 2). “Daylight and Views, Daylight for 75% of Spaces” was ranked first again. This indicated that this item is the most important for both research questions. The difference in means between the item ranked second and the item ranked sixteenth was 1.16. This indicated that there was a parallel between the ranks of research question one and research question two.

Table 2 Rank of the IEQ items from greatest gain in employee productivity for the initial cost to least gain in employee productivity for the initial cost (research question 2)

Rank	Mean	LEED item number	Item
1	4.54	16	Daylight and views, daylight for 75% of spaces
2	4.25	9	Low-emitting materials, carpet
3	4.24	8	Low-emitting materials, paints
4	4.18	7	Low-emitting materials, adhesives & sealants
5	4.11	17	Daylight and views, views for 90% of spaces
6	4.09	1	Minimum IAQ performance
7	4.05	4	Ventilation effectiveness
8	3.96	2	Environmental tobacco smoke control
9	3.89	15	Thermal comfort, comply with ASHRAE 55-1992
10	3.85	12	Controllability of systems, perimeter
11	3.78	13	Controllability of systems, non-perimeter
12	3.74	10	Low-emitting materials, composite wood
13	3.61	11	Indoor chemical & pollutant source control
14	3.43	6	Construction IAQ management plan, before occupancy
15	3.19	14	Thermal comfort, permanent monitoring system
16	3.09	5	Construction IAQ management plan, during construction
17	2.74	3	Carbon dioxide monitoring

The results of the rankings revealed a strong correlation between the perceptions of items that increase employee productivity and perceptions of return on investment. That is, if an item on the IEQ checklist was associated with employee productivity, then it was also similarly associated with a gain in employee productivity for the initial budgeted cost.

Quadrant Analysis

To visualize the relationship between the date sets, a quadrant analysis was developed.

	Quadrant I: Items that the architects perceived to be the most associated with employee productivity and most associated with the greatest gain in employee productivity for initial budgeted cost (see Figure 1 below). Therefore the items in this quadrant should provide the best value to the owner and are potentially the most important to owners when making decisions on what items in the IEQ checklist to focus on.
	Quadrant II: Items that the architects perceived to be less associated with employee productivity but still associated with the greatest gain in employee productivity for the initial cost.
	Quadrant III: Items perceived to be the least important items associated with both employee productivity gains and gains in employee productivity for the initial cost. To owners, these are the items that could be compromised if budgets do not allow for all items on the checklist to be addressed.
	Quadrant IV: Items that architects perceive to be associated with employee productivity gains, but not as associated with the greatest gain in employee productivity for the initial cost. If an owner is not as concerned with the greatest gain in employee productivity for the initial cost but is more concerned with employee productivity gains, then the items that fall into this quadrant are those that should be important during decision-making. No items fell into this quadrant.

Figure 1 Quadrant analysis of IEQ data.

Conclusions and Recommendations

The following conclusions and recommendations are based on the findings of this study.

1. The four most highly ranked items perceived by architects in the sample to enhance employee productivity were: (a) “Daylight and Views, Daylight for 75% of Spaces”, (b) “Daylight and Views, Views for 90% of Spaces”, (c) “Controllability of Systems, Perimeter”, and (d) “Thermal Comfort, Comply with ASHRAE 55–1992.” It is recommended that these top four ranked items should be given priority consideration when trying to maximize employee productivity and fit within design budgets.

2. The three most highly ranked items for research question two were: (a) “Daylight and Views, Daylight for 75% of Spaces”, (b) “Low-Emitting Materials, Carpet”, and (c) “Low-Emitting Materials, Paints.” This indicated that a majority of the sample of architects perceived these items to have the greatest gain in employee productivity for the initial budgeted cost. It is recommended that these top three ranked items should have priority when trying to compromise items to fit within budgets.

3. The quadrant analysis was designed to assist in visualizing the relationships among the two sets of IEQ items that comprise the research questions. When considering research questions one and two together, the three most highly ranked items in the quadrant analysis were: (a) “Daylight and Views, Daylight for 75% of Spaces”, (b) “Daylight and Views, Views for 90% of Spaces”, and (c) “Low-Emitting Materials, Carpet.” This indicated that out of all of the items that fell into Quadrant I, these three had the highest summed means. It also indicated that these items are perceived to have the most association with employee productivity and the most association with the greatest employee productivity gain for the budgeted cost.

4. Over 90% of the participants rated the item “Daylight and Views, Daylight for 75% of Spaces” as either a 4 or 5 on the 5-point Likert-type scale for both research questions. This item, therefore, is perceived to be the most important to increase employee productivity and to provide the greatest gain in employee productivity for the initial cost. It is recommended that this item have top priority. In addition this was the only item that was ranked higher than 2 standard deviations above the mean.

5. There is a high correlation between the two research questions, which means that if the item is perceived to be highly associated with employee productivity, then it is also perceived to have a high gain in employee productivity for the initial budgeted cost.

6. The rank listing of items for research questions one and two should be used to determine the priority of the items when trying to decide what items should be included in the project. On the other hand, when trying to decide what items should have priority, designers should first consider the highest ranked items and selectively apply the low ranked items as budgets allow.

7. Establish the items in Quadrant I and II as design priorities.

8. Compromise the items in Quadrant III first when trying to fit within budgets.

9. If the project budget only allows for some of the items in Quadrant I to be used, the rank of the items can be utilized to prioritize selection.

10. LEED should consider prioritizing the items in the IEQ checklist and utilize differential scoring so that the items that are top priority have a higher amount of points available in the LEED checklist. LEED Version 2.2 did not take this approach.

The IEQ elements of daylighting, views, low-emitting interior finish materials, thermal comfort and control, and a smoke-free environment were perceived by architects as most associated with employee productivity gains and were also considered to provide the best value for the budgeted cost. Although the estimated dollar value of employee productivity gains from improved IEQ varies widely, it is clear from the research that building features can affect workers' health and hence impact productivity, positively or negatively. It also follows that healthier employees will be more productive employees.

From the time this study was completed in May of 2004, over 1500 additional projects have been registered in the LEED certification process (USGBC, 2005). As more LEED certified buildings are completed and green buildings become more commonplace, more robust research may compare employee productivity in green buildings to that in conventional structures. Future research may provide more definitive data on the cost connection between IEQ and productivity, and thereby may provide an incentive for building owners to invest more into their building and the well-being of the building occupants.

Notes

n = 55.

n = 55.