Hand Dryer Technology and Accessible Restroom Design

The short history of commercial and public restroom design is largely linked to developments in our understanding of hygiene and public health. One major example is the Occupational Health and Safety Act signed into law in late 1970, which placed requirements on employers nationally for sanitary facilities for workers.¹ These include determinations of the number of water closets based on the number of employees, among other requirements for sanitation and health, although it did not include rules on such variables as hand-drying methods and practices.

Architects have designed solutions to meet the rules over the years, clearing budgetary and aesthetic hurdles and conforming to law, building code, good hygiene, and common sense. One rarely sees marble partitions in public restrooms any longer, for instance, not only because of the expense but also because of maintenance issues and the availability of newer, better materials. Even floor-mounted toilet bowls, once the rule, are rarely specified for new commercial restroom projects with multiple stalls.

Yet no single law or code precipitated as much innovation for the design of U.S. commercial restrooms as the Americans with Disabilities Act of 1990 (ADA). Along with updates to building and energy codes and standards for sustainable design, ideas and rules promulgated through the ADA drive design teams to high-performing, efficient restroom systems that require little maintenance and are relatively easy to use for all occupants and visitors. Restroom product manufacturers have responded with thousands of innovations supporting these goals, from partitions to flush systems to hand dryers.

Of the myriad issues surrounding commercial restroom design, the development of novel high-speed unheated electric hand dryers, including air-knife technology, is an emerging opportunity for continued innovation. A look at the context in which it plays an increasing role is a valuable start.

New technologies are changing restroom design, such as this restroom fixture that combines an air-knife-type hand dryer with a touchless water faucet, to be mounted above the lavatory sink. Image courtesy of Dyson Inc.

Current Best Practices

Restroom design is too often left as an afterthought, when project teams reason the spaces don't claim much time or attention from occupants. Yet, efficient, hygienic, and enjoyable restrooms can boost occupant and visitor experience, while improving occupant and public health. It can also dramatically impact operating costs for common areas and energy and water loads. According to a 2011 Harris Interactive survey, 94 percent of U.S. adults said they “would avoid a business in the future if they encountered dirty restrooms.”² Key concerns for restroom design include:

• Layout. Appropriate planning should address privacy and likely user habits to improve aesthetics and reduce the number of surfaces users touch. The use of doorless public restrooms with “maze entries” ensure privacy and eliminate the hygiene issues associated with door handles.

• Fixture count. Building and plumbing codes require a certain number of toilet, urinal, and sink fixtures based on expected occupancy and usage. Historical use data and context on health provide guidance on whether minimum code requirements are appropriate. Public assembly venues, for example, have strict “potty parity” rules in many states, meaning a typical 2-to-1 ratio of women's toilets to men's fixtures, to prevent long lines at event times.

• Maintenance. Certain fixtures, components, and hardware may be relatively self-cleaning or -maintaining, like electric hand dryers. Architects and their clients should consider the likely maintenance staffing and schedule during occupancy, and specify to suit.

• Ventilation. Inappropriate venting can lead to odor-related dissatisfaction with the facility, as well as moisture-related problems with mold and mildew. There's also a rule of diminishing returns—overventing with high-speed fans that run for too long increases operating energy loads without a commensurate payoff in air-change performance.

• Vandalism. Often considered a maintenance issue, vandalism can be reduced by concealing valves and using tamperproof materials and hardware. A bathroom free of apparent vandalism is likely to leave a more positive impression of the host facility.

Many commercial restroom designs meet minimum code requirements but the layout of use points is impractical, for example, where hand-drying equipment is away from the sink. Image courtesy of Dyson Inc.

With these general rules, architects then look to the specifics of the building types and occupancy needs. Restroom design is complicated issue with no single best solution; the flush fixture used successfully for multiple-stall restrooms of sports arenas, for example, may not deliver the same performance benefits in the locked-door, single-occupancy restrooms of a medical office building. In all cases, the role of the facility manager in restroom operations may be a benefit for understanding usage and occupant preferences. Yet a facilities director at a small college may have preferences or standard specs for restroom accessories that have worked well in certain building types, that do not work well for new or renovated buildings with a change of use. In these cases, architects may opt for the standard the client prefers; but often it's wise to stress consideration of the most appropriate solutions, even if they are not the college standard.

That said, the most important factors for restroom facility design are universal: efficiency and economic impact, sustainability, safety, hygiene, accessibility, and comfort. Minimum acceptable levels for these variables are codified—except for comfort—and the codes vary by jurisdiction. The factors significantly impact the occupant population as well as the buildings, their owners, and the indirectly affected populations, such as other people in the community.

Consider for a moment a conventional public restroom that meets minimum code requirements, in which the hand-drying equipment is placed just a few feet away from the sink. This may meet code, but it will lead to users dripping water on the floor between the two stations, creating a possible slip hazard. The distance between the two use points may be especially frustrating for a wheelchair occupant, who must operate her chair with just-washed hands in order to reach the towel dispenser or electric dryer.

This defeats the purpose of washing in the first place: leaving the facility with sanitized hands. Savvy architects look to avoid this kind of design error, for example by drastically reducing the distance between the sink and the drying accessory, or by designing to avoiding situations where hand dryers blow water from wet hands down and onto a wheelchair user's lap, as is the case with like conventional warm-air hand dryers. As an alternative, state-of-the-art restroom products often address these issues, such as novel “hands-in” electric hand dryers or new touchless water faucets with integral electric hand dryers that have recently come onto the market.

A recently introduced alternative restroom product combines automatic, touchless water faucets with integral electric hand dryers—a combination fixture/accessory system that limits dripping on the floor, encourages drying, and boosts user convenience and ergonomics. Image courtesy of Dyson Inc.

Solutions like this combined fixture/accessory system help incorporate best-practice design thinking with new opportunities for end-user ease and convenience. Though currently such solutions are rare, they will advance as they bring long-term payoff on the triple bottom line of economic, environmental, and social benefit. They provide a simplified solution with reduced operations costs, improved green performance, and even improved accessibility or use for the wheelchair-bound, while providing all of the required hygienic properties.

The ADA and Accessibility

As applied in ADA, disability is a broad term, not limited by the legislation, describing those considered physically or mentally challenged. The entire purpose of the act, in fact, is to eliminate barriers to access for those with disabilities, prohibiting any discrimination by word or deed that prevents any American from equal access to goods and services. Since its passage, the law has been applied more liberally to groups of Americans not necessarily considered disabled or handicapped.

Although there has been some controversy around what can legally be considered sufficient access and who is disabled, the response to the legislation overall has been positive. The design community continues to strive to provide equal access for Americans facing many types of challenges, including:

• those with stability and balance impairments

• the short (including children) and the tall, large, or heavy people

• those with temporary impairments involving casts, slings, crutches, and the like

• mobility equipment users (power wheelchairs, scooters, walkers)

• the elderly

• the blind and vision-impaired

• the deaf and hearing-impaired

• individuals who need assistance in the restroom.

In fact, discussion in the design community has shifted from ADA compliance and accessibility to universal design. This relatively new concept describes spaces, furnishings, and tools that are equally usable by all. Though the term has a distinct meaning—not about compliance with ADA, but rather for an approach to design—they may be used interchangeably to describe the intent of a scheme or component. In addition, state and local jurisdictions do not all agree what constitutes proper access. ADA provides a minimum, and some authorities and agencies raise the bar for accessibility beyond what is outlined federally, as with building codes, energy-efficiency requirements, and green-building standards.

Paper towels can cause maintenance issues, including blockages that clog wastewater systems and overflowing trash receptacles. Image courtesy of Dyson Inc.

California, Massachusetts, and Texas are three states that determine and publish their own statewide accessibility guidelines, intended to improve upon the ADA and make the state's public facilities even more broadly and uniformly accessible for all users. The state-specific standard may use ADA compliance as its baseline, but this is not the same as a state building code simply referring to ADA requirements and ANSI/ICC guidelines. Even if the differences are minor, as they are often described in reference to the Texas Accessibility Standards, for instance, the state's decision to apply its own standard means that violations can be met with enforcement and regulation by state agencies.

Equal Access for All

To be ADA-compliant, a restroom must meet strict criteria, a summary of which can be found in the table below. For detailed compliance requirements, architects refer toICC/ANSI A117.1 – Accessible and Usable Buildings and Facilities, which is referenced in the International Building Code (IBC).

ANSI/ICC guidelines for compliance also outline reach ranges and mounting heights for restrooms to be utilized primarily by children, and requirements for installation of elements to allow approach and use by both the left- and right-handed. Furthermore, these guidelines also address planning and layout for bathroom space and entryways. These planning guidelines are similar to those for other rooms, halls, and areas with certain adjustments for maneuvering clearances that may be unique to restroom spaces.

The accessibility standards for bathroom planning are complex, but the goal is always the same: equal access for all. Keeping this goal in mind helps to make sense of the standards and to translate them into design. For instance, it is clear that an open vestibule provides the freest access to all users. If that is not possible in the given application, the designer must then consider the best door configuration (single-door, opposing door, etc.) and manage the requirements for maneuvering clearances. Modern accessible restroom design should be free of raised thresholds at entry points, though beveled thresholds of no more than ½ inch in height can be considered compliant, depending on the relationship of the height and incline. The ICC/ANSI standard also addresses maximum force needed and hardware types and mounting heights for operating doors.

The ANSI/ICC standard for accessible restroom design is exhaustive and addresses requirements for space, reach, maneuvering, force, and access in numerous configurations, including everything from single-occupancy facilities to large multi-fixtured public restrooms to bathing facilities. Yet it is just a start. New best practices and technologies can be harnessed to deliver restrooms that are not only accessible, but also comfortable, attractive, sustainable, efficient, and hygienic. One of those areas with rapidly changing technology is the lavatory and sink area.

Handwashing and Drying Area

Handwashing presents a special challenge for both accessibility and comfort. For example, a lavatory arrangement may meet accessibility requirements and even include low-flow water fixtures. But the reductions in water usage (and associated operations and water utility costs) may be offset by frustrated building occupants experiencing an outsize negative impact due to the specification—such as handwashing in an industrial setting, where low-flow simply may be inappropriate and even lead to wasted water. The same is often true for certain combinations of faucet-operating hardware and low-flow plumbing.

Ultimately, the best design will result first from establishing likely user habits before designing the lavatory. Second and as with all design efforts, thorough planning is essential.

ADA Guidelines

The ADA outlines certain requirements and clearances for lavatories and sinks. These include:

• The highest point of the rim or counter surface 34 inches above the floor

• Knee clearance a minimum of 27 inches between the floor and the bottom of the sink apron

• Knee clearance under the lavatory at least 8 inches deep from the front

• Minimum toe clearance of 9 inches above the floor

• Forward approach requires 30-inch by 48-inch clear floor space, as described earlier.

These and other guidelines address various configurations and possible overlaps in application. As an example, lavatories in commercial and institutional single-occupancy restrooms may not occupy the space above any portion of clear floor space for toilet access. Any exposed plumbing and hardware under the lavatory must be covered and protected, as exposed pipes cause injuries and burns to wheelchair users in some cases.

The ADA places requirements on installation of such items as soap dispensers, mirrors, towel rolls and dispensers, waste bins, and electric hand dryers. These are important minimums to follow, but they are insufficient to creating a high-performing restroom. Consider for instance what ANSI/ICC 117.1 requires for reach with respect to hand dryers and paper towel dispensers:

 

Operable parts on towel dispensers and hand dryers shall comply with Table 606.7.

 

This is crucial information, but it does not mandate the relationship between them, including distances between these elements and the lavatory or waste receptacle. It does not consider the issue of water on the floor, which can cause slip-and-fall accidents, or the experience of water dripping into one's sleeves or a wheelchair user's lap. Although a number of valuable recommendations are included, many other relationships are largely left to the architect's better judgment.

Health and Hygiene

Consider the design of restrooms for a workplace. Casual interaction between employees is responsible for much of the passing of contagions, which is why agencies like the Center for Disease Control (CDC) encourage employers to inform employees of the importance of hand washing. Research reported to the CDC indicates that educating employees on the importance of hand washing can reduce cases of diarrhea by 31 percent (58 percent for those with weakened immune systems) and respiratory illnesses like colds by 21 percent.³ This is due in part to the fact that, as some research indicates, as few as 31 percent of men and 65 percent of women wash their hands after using public bathrooms.⁴ In addition, research by Leeds University and Bradford University has shown that a person with dry hands is about 1,000 times less likely to cross-contaminate other people. Clearly, getting hands clean—and dry—is very important.

If illnesses can be avoided, not to mention injuries from accidents that could arise from slips on wet floors, this translates into safer work environments for employees and more productive workforces, which would certainly benefit the employer. This provides yet another reason to consider likely user habits, best practices, and technological advances in bathroom furnishings before finalizing a restroom design.

Again, it is always advantageous to reduce the space between sinks and drying options to reduce the amount of water on the floor and the associated mold, bacteria, slip hazards, and the like. As for which drying option to choose, at least one recent study in the U.K. suggests that paper towels are more hygienic than dryers,⁵ but this ignores the problem of paper towel waste cluttering the restroom, which is itself unhygienic. It also ignores the practical matter of user habits: A restroom user would have to ring each finger to achieve the same level of dryness as achieved by today's air-knife-type hand dryers, which achieve the NSF standard of 0.1 grams of water.

Also, the U.K. study fails to distinguish between warm-air and high-speed dryers, according to experts. Warm-air dryers can harbor microbes, offering an environment in which they can thrive and multiply. High-speed dryers using HEPA filtration are shown to capture at least 99.97 percent of bacteria from the air being used to dry hands, which the National Sanitation Foundation protocol NSF P335 (“Hygienic Commercial Hand Dryers”) establishes as a working definition of “hygienic” for dryers. There are other reasons to consider the new hand dryer technologies. For example the novel air-knife designs eliminate the “catchbasin” element of some trough-style hand dryers and moves a stream of air that is powerful enough to atomize water into vapor. Hand dryers with a drain cartridge do not share the issue of trapping water, as with a trough-style device.

Sustainability

A number of issues factor into making sustainable design choices in restroom design, most of which fall into one of two major categories: whether they contribute to healthy indoor environmental quality (IEQ), positively impacting occupants and visitors, and whether the choices sufficiently reduce their potential for negative impact on the planet.

Improving the IEQ of restroom environments can come through detailed research into specified elements. For instance, not only should finish materials be low- or zero-VOC-emitting, but the same should be true of cleaning supplies regularly used by maintenance staff. Restroom design that eliminate or reduce opportunities for microbes to thrive or be transmitted are crucial to positive IEQ. Around the lavatory these strategies include eliminating paper towel waste, specifying dryers without heating elements, and removing requirements for touching operable elements. This latter option is especially important: The American Journal of Infection Control has reported that microbes can survive on many surfaces for up to 72 hours.⁶ Eliminating the need for touching surfaces makes the relative success of each instance of washing more likely to successfully sanitize hands.

Of course, specification of automatic, touchless fixtures and accessories—such as faucets, soap dispensers, hand dryers, and towel dispensers—must include some research into operations failure rates. Fixture or accessory failure will encourage users to touch the elements in hopes of activating them, and potentially will discourage the washing hands in the first place. In general, however, touchless bathroom elements are not only the most hygienic option, but also frequently the most conducive to universal, accessible design and ADA compliance as well as sustainable design. In fact, new LEED versions include credits awarded for universal design, such as the recently piloted Credit 34, Design for Adaptability.

Making sustainable choices in bathroom elements also requires consideration of such issues as embodied energy, atmospheric carbon, output to landfill, and so forth. On a global level, the impact of drying option selection could have a significant environmental impact in aggregate.

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.

Hands Up, or Hands Down?

There is more to effective restroom design and user-friendliness, including opportunities for better ergonomics based on advances in accessory and fixture designs. The recent introduction of products such as hand dryers that allow for a hands-down positioning, for example, opens the door to several advantages in user comfort and experience.

Traditionally, electric warm-air and high-velocity hand dryers are wall-hung units that blow down on the user's hands. These appliances can be mounted at a variety of heights, so the user's hands are at approximately shoulder height or at or below waist height, or at a position somewhere in between. Novel air-knife product designs, however, allow the user to put their hands over and into a visually defined hand-drying zone. The accessory is designed to allow for water to move downward on the hands, and the air-knife has the “scraping” action that moves water in addition to the typical evaporative effect.

Other ergonomic concepts include high-speed units that allow for horizontal hand insertion, where air blows down and back from vents on two sides. It mimics the position used for handwashing. This can be a comfortable position for a majority of the population, who can dry hands without bending over or bending their knees. However the design must consider the needs of wheelchair users, younger users and other special-needs occupants, who may need or prefer a lower mounting height.

Hand positioning and the direction of air movement are considered in this combined hand-washing and -drying system. The washing and drying zone is visually defined, and water is pushed downward on the hands via a “scraping” effect of the air-knife output in addition to the typical evaporative effect. Image courtesy of Dyson Inc.

Following on this notion of mimicking handwashing is the recently introduced combination hand dryer and touchless water faucet, where the accommodations for user's sink and drying needs are integrated in one system. In this case, excess water drips into the sink. In terms of resources, the pairing of two needs provides a one-to-one supply—every sink has a dryer—so redundancy is not an issue of user-friendliness. The concept also provides immediate access and reduces required user movements, which is a benefit for mobility-impaired users. The idea also improves hygiene in a number of ways; the most obvious example is that a wheelchair user will not have to touch his or her wheel handrails between washing and drying.

This concept meets several tests of user-friendliness as outlined above: Access, proper height, redundancy and standardization, as well as reducing required user movement. In terms of visibility, the system design must make it clear that it performs the dual function. The solution in some cases is to automate the function using hands-free sensor technology. This allows the user to have a single-location, hands-free washing experience: a sensor faucet and automatic soap dispenser, for example, followed by immediate warm air operation in the same target area as the washing.

Acoustics and Other Factors

There are other usability and comfort issues that impact user-friendliness and positive restroom experience that go beyond the physical and cognitive dimensions of ergonomics. One is the design effectiveness of restroom accessories, hardware and fixtures, which vary widely in terms of quality, value, cost-benefit, and life-cycle performance. Field experience often informs the procurement practices of many commercial and institutional end-users. Architects can supplement these practices with a thorough analysis of key accessory design variables.

One of those is accessory acoustics. In general, noise levels in restrooms have increased over the last decades, with more powerful exhaust fans, flush valves, hand dryers, and even seemingly innocuous features, such as roll towel dispenser levers, faucet aerators, and automatic soap dispenser pumps. The cumulative noise in a restroom with multiple users can detract considerably from user enjoyment—and the likelihood of proper hygiene. Yet in many codes and standards, restrooms are dismissed as “acoustically insensitive” environments.

At the same time, acoustic comfort is an IEQ issue and a LEED credit in some situations. It is also recognized as a serious consideration in all types of facilities, and potentially a code issue or health concern when very-high-frequency or loud electrical equipment is used. Clearly, says one maker of acoustical surfacing products, “Architectural design and building acoustics have a significant correlation when it comes to human satisfaction, learning, and productivity … and all factors of acoustics that should be considered in architectural design.”⁸

For the special case of high-speed hand dryers, studies of acoustics have shown that the “acoustic readings of high-speed hand dryers can be akin to the noise of a road drill at close range,” says John Levack Drever, a faculty member at Goldsmiths, University of London, and author of Sanitary Ambiance: The Noise Effects of High-Speed Hand Dryers.⁹ The noise is invasive and an annoyance—a technical term the World Health Organization says has direct effects on various activities, including “interference with conversation, mental concentration, rest or recreation.”¹⁰ There are other more pernicious effects, says Drever, for the elderly, dementia sufferers, the visually and hearing impaired, and children with autism spectrum disorders. Users with misaphonia and hyperacusis have heightened sensitivity to sounds in certain frequencies; for them exposure can be painful.

Several advances in dryer technology address these issues while still maintaining high effectiveness of hand drying and low drying times of 12 seconds or less. These include:

• Digital motor windup and wind down control. New motors employ digital speed regulators that are part of the motor controller package. These have with integral capabilities to correct windup and wind-down performance, which allows precise speed regulation and relatively rapid acceleration while producing minimal acoustic noise.

• Helmholtz technology. Some appliances and building MEP equipment today employ Helmholtz resonators or oscillators to eliminate undesirable high-frequency or low-frequency noise. These noise-cancelling designs typically work by adding a resonant chamber to an exhaust port or other area with moving air or vapor, and the chamber is designed to produce a sound wave that is reflected back to the air stream, canceling the noise. The basic physics are similar to blowing air into an empty bottle to create the cancellation wave.

• Motor tonalities. Research on motors and engines has resulted in a variety of ways to simply engineer the components and enclosure to create more pleasing tonalities and sound quality. These techniques have been applied to automobile and appliance design for decades.

New motor designs include such features as digital motor windup and wind down control to improve precision and acceleration, as well as engineered motor tonalities and Helmholtz resonators or oscillators, which eliminate undesirable high-frequency or low-frequency noise by means of producing noise-cancelling sound waves. Image courtesy of Dyson Inc.

With advances like these, the architect can pay more attention to the sound produced by noisemaking appliances inside the restroom. The result is not only better acoustics but also a valuable way to contribute to user-friendliness and therefore better hygiene and user affinity.

Sustainability and the Environment

There are other potential environmental considerations for designers of restrooms. A few are relatively new and bear consideration.

Health Product Declarations (HPDs)

The use of environmental product declarations (EPDs) has led to wider and more effective adoption of life-cycle assessments (LCAs) as well as more definitive calculations of recycled materials and embodied energy from extraction, manufacturing and transport. This innovation has also led to the creation of an industry group and a method for disclosure of product ingredients and chemical composition. These are called health product declarations or HPDs, and an HPD Open Standard was promulgated in 2012 to accommodate “differences in the ability and readiness of manufacturers to disclose highly variable contents in many diverse products,” according to HPD Collaborative, an industry group that published the standard.¹¹

A number of restroom product manufacturers have completed EPDs and HPDs, and make them available to project teams to ease comparisons about product environmental impacts and formulations. Presented according to accepted protocols and standards, the declarations are now used among manufacturers, end-users, specifiers and suppliers as a basis for project development and for documentation as required by product certifiers and building standards organizations.

The trend is toward “full disclosure” of product formulations and impacts, which has a number of benefits for restroom design. First, products comprising materials and components from multiple sources can provide a full accounting of their supply chain. Second, any chemicals or materials deemed unsuitable for the restroom end-use may be quickly identified. Third, any requests for information (RFIs) on product contents or impact can be sent and answered in a “common format,” says HPD Collaborative.

HPDs provide for an inventory of product contents, and an assessment of those contents against authoritative Hazard Lists, which detail for example toxic agents and known carcinogens, among other dangerous substances. The HPD formats also detail what types of product testing has been undertaken, and what levels and types of compliance the products have achieved. Of note for restroom design, the building operations phase is included in the declarations. EPDs include energy required for operations, for example, and HPDs cover materials required for installation, maintenance, cleaning and operations.

Source Reduction

This raises another important aspect of restroom life-cycle or ROI calculations. The requirements for an energy-consuming device in the operations phase, for example, may vastly exceed it embodied energy from manufacturing and transport. Similarly, the savings from an automatic foam soap dispenser over 10 years may be vastly exceed the initial expense to cover its embodied energy and installation.

The same is true of reduced paper use, which has been the subject of many authoritative studies on the choice between hand-drying methods and appliances.

Paper towels also cause maintenance challenges, ranging from blockages that clog wastewater systems to overflowing trash receptacles. Also there is the need to refill empty towel dispensers, which requires labor hours as well as leaves some portion of paper availability unfulfilled, limiting end-user access and reducing user-friendliness. Yet even more important are the hygiene and image issues relating to paper refuse in the restroom.

Disposing of paper towels, sanitation costs, and transport costs to carry paper towels to the landfill are the primary environmental issues associated with this hand-drying method. As in Clarke's analysis, the college or school district with 4,000 students paying about $0.01 per paper towel would pay $20,000 per year for the paper only. The cost of carting and disposal depends on several variables, but is not included in this figure. For this reason alone, a number of architects and sustainability consultants have been discussing the use of both electric and paper drying or a switch to electric for that 90 percent of nonresidential facilities without them.

One of the bottom-line measures to encourage the use of one method or another is carbon footprint, and the comparison between paper and electric drying methods can show a reduction in total carbon emissions. To demonstrate proof of a product's associated carbon output, there are certifications available, such as the Carbon Trust's carbon reduction labeling program. These certification labels communicate carbon footprint measurement, certification and reduction for specific products and services. There are two “Carbon Footprint” labeling types: Reducing CO₂, which shows that the manufacturer has measured and had certified the carbon footprint of its products and services and, if applicable, the maker's commitment to reducing it. The CO₂ Measured label communicates your achievements in accurately measuring carbon footprint and disclosing the results, according to Carbon Trust.

The use of such labeling is one of a long list of techniques that architects may consider for addressing the myriad issues surrounding commercial restroom design. With the ADA, sustainability issues, ergonomics and comfort in mind, the design team will benefits from a number of potential resources to address complex needs. The development of innovative products—such as high-speed unheated electric hand dryers, including air-knife technology and combined water faucets and electric dryers—is just one of the emerging breed of products and systems to help address the challenges.

 

ENDNOTES
1	http://smallbusiness.chron.com/osha-laws-restrooms-workplace-1332.html
2	http://www.cintas.com/FacilityServices/Press-Releases/Independent-Study-Dirty-Restrooms-Lead-To-Lost-Business.aspx
3	http://www.cdc.gov/healthywater/hygiene/hand/handwashing-corporate.html
4	http://www.cdc.gov/healthywater/hygiene/hand/handwashing-corporate.html
5	http://www.dailymail.co.uk/health/article-2335811/Ditch-hand-dryer-Paper-towels-MORE-hygienic-remove-germs.html
6	http://www.ajicjournal.org/article/S0196-6553%2807%2900595-0/fulltext (“The effectiveness of hand hygiene procedures in reducing the risks of infections in home and community settings...”)
7	http://www.ncbi.nlm.nih.gov/pubmed/17425239
8	http://continuingeducation.construction.com/crs.php?L=31&C=967
9	www.academia.edu/1238491/Sanitary_Ambiance_the_noise_effects_of_high_speed_hand_dryers
10	“Guidelines for Community Noise,” WHO, Geneva 1999
11	http://www.hpdcollaborative.org/use-the-hpd.html

 

Dyson is about developing new technology and making things work better. Environmentally responsible engineering is efficient engineering. Doing more with less. Creating machines that consume less energy and are made of fewer raw materials, but are better performing. Dyson’s function-led approach to design supports this aim. airblade.dyson.com