According to estimates cited in Crain's, hand dryers are in place in about 10 percent of nonresidential restroom locations in the United States. From this one can infer that millions of locations today are buying and disposing of bulk paper for restroom operations. According to Todd Clarke, director of specifications, Dyson Inc., “For U.S. buildings, a hand dryer may be a small part of a facility's footprint, but across the whole market it can have a very big impact.” As an example, Clarke describes a small college building serving a student body of 4,000. If each student washes his or her hands once per day using two paper towels, over a 200-day school year the consumption of paper towels easily reaches into the millions. Total use would be calculated this way: 4,000 x 2 towels x 200 days, or 1.6 million towels.

It should be no surprise then that designers are paying more attention today to hand-drying methods and product review. While a new or renovated building may achieve the U.S. Green Building Council's LEED® Platinum certification regardless of the choice of hand-drying method, the designer who wishes to make the most sustainable choice will seek to reduce waste even though it will not necessarily help to acquire points toward certification. Another benefit is using methods that reduce water use, which can earn LEED credits for water efficiency. In addition, the choice of hand-drying method can have a valuable contribution to LEED's Energy & Atmosphere (EA) credits, as well as impacting the LEED category of Materials & Resources (MR). And there is a new credit category in upcoming versions of LEED for using products that have undergone a published life-cycle assessment (LCA).

Unfortunately there are precious few standards or measures to help the designer easily sort out the best option. But there is new, potent research indicating that certain options are far more environmentally sustainable, especially when compared in apples-to-apples fashion through well-documented LCA.

Ergonomics: Physical Principles for Wash Areas

• Keep everything within easy reach. • Set work surfaces at proper heights. • Allow work using good posture. • Reduce excessive forces. • Minimize fatigue. • Reduce excessive repetition. • Provide clearance and access. • Minimize contact stress. • Provide mobility and change of posture. • Maintain a comfortable environment. Cognitive principles are also valuable for enhancing ergonomic design. These include: • Standardize and employ stereotypes. • Link actions with perceptions. • Present information at an appropriate level of detail. • Present clear images. • Use redundancies and patterns. • Provide variable stimuli. • Provide instantaneous feedback. Adapted from: MacCleod, D., The Ergonomics Edge: Improving Safety, Quality and Productivity, 1995

 

Life-Cycle Assessment (LCA)

When comparing drying options for sustainability, the specifier must understand what a particular LCA says and the assumptions underlying it—which may vary significantly from source to source. Some results may comply with an accepted standard such as the ISO 14040 and 14044 LCA standards, but many do not. With so many LCA studies on the market conducted with differing standards, it is difficult for architects to glean useful, equivalent data for specification.

A recent meta-study by a Boston-area research university addressed this issue using ISO-based LCA methods to analyze the studies while ensuring a consistent basis of comparison. According to the authors of the mid-2011 analysis, Life-Cycle Assessment of Hand-Drying Systems, the compilation of industry data required establishing a “functional unit” (a pair of dry hands), an inventory analysis for unit processes (quantification of resource requirements and emissions to the environment), impact assessment, and finally, interpretation of the results.

Comparing data for seven hand-drying systems—cotton roll towels; virgin content paper towels; 100 percent recycled paper towels; a warm-air hands-under electric dryer; a high-speed hands-under dryer; and two high-speed hands-in dryers—the Cambridge, Mass.-based Materials Systems Laboratory (MSL) found a marked difference in energy used is when paper-towel drying is compared to high-speed electric. In addition, they found that novel high-speed dryers offer substantially better life-cycle performance than standard warm-air dryers.

In fact, standard warm-air dryers ranked last in the MSL review of LCA studies for global warming potential (GWP), with the highest environmental impact. This will shock many, who probably assume that warm-air dryers would be more eco-friendly than paper towels.

As for why high-speed dryers top the list in sustainability, the answer lies largely in the amount of time required to achieve the “functional unit” of two dry hands. Warm-air dryers run longer and use electricity for the heating element as well as the fan. High-speed dryers require far less time to dry the pair of hands, and do so without heat. And this is especially true for designs that use air-knife technology for hands-in drying.

An air knife is a highly concentrated sheet of air projected through a slot or multiple openings, and generally used to remove moisture quickly from a surface. This is commonly seen in automated car washes, applied through industrial drying arms with rollers that guide the arm over and around the contours of the car. One leading maker has applied this technology to a hands-in dryer design, through the use of digital motor technology, which scored well in the MSL LCA meta-study.

User Experience and Hand Drying

Beyond the ADA and legal issues regarding accessibility, there are practical considerations of good restroom design. These include accessibility as an idea of convenience, user-friendliness, and comprehensibility—qualities that good architectural designs must share. They also contribute to better hygiene and public health by making it easier for occupants and the public to find and use sanitary facilities, as studies show. Comfort is an increasingly important aspect of restroom design also, especially as senior citizens and family users require accommodations in general, not to mention the special case of users with limited needs.

For handwashing and hand-drying areas, there is little guidance from official sources, code-making bodies, or the ADA on how to design for ergonomics, comfort, and convenience. According to the Baltimore-based American Restroom Association (ARA), “In the United States, the International Code Council (ICC) provides well thought-out and well-vetted requirements for the availability of public toilets in structures,” yet “there is remarkably no national public health mandate for toilet facilities.” Instead, architects and designers must go beyond the 2010 ADA Standards for Accessible Design guidelines to consider basic issues of intuitive, comfortable use and good ergonomics in addition to minimum criteria for clearances and reach. (One valuable resources is ergonomics consultant Dan McLeod's The Ergonomics Edge: Improving Safety, Quality and Productivity; see the sidebar, “Physical Principles,” above.)

A study by the researchers Gautham Suresh, M.D. and John Cahill, M.D., at the Medical University of South Carolina Children's Hospital, Charleston, considered the “user-friendliness” of hospital facilities for practicing hand hygiene. They theorized that poor user-friendliness could be a cause of “nonoptimal hand hygiene” due to “violations of ergonomic principles in the design of hospital environments.”⁷ (A second issue was the lack of timely replenishment of consumables, such as soap and alcohol-based hand rubs, or ABHRs.)

Suresh and Cahill developed an ergonomics-based tool called SWAG, which referred to the four main hand hygiene resources: sinks, waste receptacles, ABHR dispensers, and gloves. Their conclusion was that a few simple, inexpensive changes using ergonomic principles can improve user comfort and enjoyment while also promoting better hand hygiene in hospitals.

Studying scores of restroom or washing areas, they identified “several deficiencies in the structural layout of hand hygiene resources” that are serious enough to hinder usage, including:

• Poor visibility. Visibility affects usership and also convenience. Surprisingly, not being able to see a fixture, dispenser, dryer or even a partition door can also be the first issue with user comfort as well. A 180-degree rule described by Suresh and Cahill assists in testing for proper visibility while architects are in the schematic design or design development phases: Upon entry to the restroom, will the sink be visible within a 180-degree field of vision?

• Difficulty of access. Obstructed reach and poor mounting heights are among the convenience and ergonomic issues affecting user access. Another is the clear space or “convenient access,” or both, from one resource or accessory to the next, used sequentially. For example, how is the clearance from faucet use to soap dispenser use to the hand dryer or towel dispenser? The need to walk from one to another is suboptimal, to say the least; being blocked by another occupant is a nuisance as well as an awkward user moment, creating another impediment to hygiene. The design rule is to avoid “wide spatial separation of resources used sequentially.”

• Placement at undesirable height. Sinks and dispensers should be placed at heights that serve a reasonable percentile of the user population. (A percentile is a statistical measure showing how many people fall into a group below that measure.) Data on elbow heights for men and women, for example, are used as typical measures for mounting restroom accessories. Dispensers should be height-adjusted to fit within the range for the target percentile; for a unisex bathroom, a dispenser set 85–110 cm above the finished floor will encompasses the 95th percentile for U.S. men—almost all—yet only the 5th percentile for elbow height for U.S. women.

While this seems to suggest that unisex handwashing areas, a trend in some urban hospitality markets, and institutional end-uses, will not likely allow for optimal user-friendliness, it is a verifiable means to optimize comfort and ergonomic suitability. Using the data is “likely to allow providers of different heights to use these resources comfortably, without having to stretch, stoop, or place their hands at uncomfortable angles,” according to Suresh. A good example is doorknob height – as well as access, since levers and knobs require unique end-user approaches and hand movements.

• Lack of redundancy. It is simply more convenient to have more options, in general, while using a restroom. Part of this is choice, such as being offered two ways to dry hands. Redundancy is another desirable feature, so that additional resources of the same type as a primary offering are available. This does not include availability of refills for recharging a dispenser, such as spare paper towel rolls that users must handle or install. Redundancy is in-kind availability. “Redundancy ensures the continued availability of a resource when the primary one is depleted or nonfunctioning and is especially important … where timely replenishment of consumable resources does not occur,” according to Suresh and Cahill. However, redundancy of hand hygiene resources is only infrequently present in our study.

• Lack of standardization. In the workplace, schools, commercial kitchens, healthcare facilities, industrial buildings and other occupancies, the use of standardization is an element of good restroom design and accessory specifications. Similar to the use of common mounting heights for light switches, standardization provides users with “predictable knowledge of where these resources are located when they enter a restroom or other work area. It is also a means to promote compliance, such as ensuring that users turn off the lights or throw away used paper towels.

These effects are best described by the cognitive scientist and usability engineer Donald Norman, who wrote in The Design of Everyday Things (1988), in which he explains why some designs please users while others only serve to frustrate and annoy.