Proceedings of Meetings on Acoustics

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Proceedings of Meetings on Acoustics Volume 19, 2013 http://acousticalsociety.

1 Proceedings of Meetings on Acoustics Volume 19, ICA 2013 Montreal Montreal, Canada 2-7 June 2013 Architectural Acoustics Session 1aAAb: Cultivating the Sustainable in Architectural Acoustics 1aAAb1. Achieving the acoustical credit within the Leadership in Energy and Environmental Design (LEED ) for healthcare green building rating system and changes within the forthcoming 2014 Guidelines Daniel M. Horan* and Jean-François Latour *Corresponding author's address: Cavanaugh Tocci Associates, Inc., 327 F Boston Post Road, Sudbury, MA 01776, dhoran@cavtocci.com The 2009 LEED for Healthcare green building rating system includes a total of 2 possible points to be earned by satisfying the requirements of the Indoor Environmental Quality Credit 2 (IEQ Credit 2: Acoustic Environment). This credit references criteria that are defined by the Facility Guidelines Institute's 2010 Guidelines for Design and Construction of Health Care Facilities (2010 FGI Guidelines). The acoustical design requirements of the 2010 FGI Guidelines will be summarized, as well as a brief history of the FGI document itself. The FGI Guidelines document is currently being revised for the 2014 edition. Proposed changes in the 2014 edition will also be briefly discussed, as we anticipate that future versions of the LEED rating system will reference the 2014 FGI Guidelines. The presentation will be made in English by Mr. Horan, secretary of the FGI's Acoustical Working Group (AWG). Mr. Latour, a French-Canadian member of the AWG, will be available to help respond to any French-speaking audience members during Q&A. Published by the Acoustical Society of America through the American Institute of Physics 2013 Acoustical Society of America [DOI: / ] Received 22 Jan 2013; published 2 Jun 2013 Proceedings of Meetings on Acoustics, Vol. 19, (2013) Page 1

2 INTRODUCTION In 2011 the U.S. Green Building Council (USGBC) launched their LEED for Healthcare Rating System. Within this system, projects can earn up to two points by meeting the requirements of Indoor Environmental Quality (IEQ) Credit 2. One point can be earned by meeting the requirements for Sound Isolation and Room Noise, and one additional point can be earned by also meeting the requirements for Acoustical Finishes and Site Exterior Noise. In each case, the document that LEED for Healthcare references is the Facility Guidelines Institute's 2010 Guidelines for Design and Construction of Health Care Facilities [1] (hereafter referred to as either FGI 2010 or the Guidelines). HISTORY OF THE FGI GUIDELINES The implementation of the Hospital Survey and Construction Act (Hill-Burton Act), passed in 1946, included the publication of the original General Standards in 1947, and in 1974 the document was retitled the Minimum Requirements of Construction and Equipment for Hospital and Medical Facilities. In 1984 the Department of Health and Human Services (DHHS) approached the American Institute of Architects Committee on Architecture for Health (AIA/CAH) to revise the document, and this led to the American Institute of Architects publishing the 1987 and editions. The Facility Guidelines Institute (FGI) was formed in 1998 to ensure that the Guidelines document would continue to be regularly reviewed and updated. This is only a brief summary of the history of the FGI Guidelines. A more complete history can be found on the FGI website at FGI GUIDELINES ACOUSTICAL CRITERIA The 2010 Guidelines set minimum acoustical criteria for the design of medical facilities in several general areas of concern. These areas of concern include: site exterior noise, acoustic finishes, room noise levels, sound isolation, speech privacy and building vibration. All of these areas of concern are referenced by LEED for Healthcare with the exception of building vibration. Site Exterior Noise FGI 2010 requires that health care facilities be designed so that the sound isolation provided by the building envelope (the exterior wall/window assemblies) will result in appropriate interior noise levels. Noise sources to be considered include preexisting and future environmental noise sources as well as health care facility noise sources (HVAC or other equipment). Facility noise sources to other nearby receptors (neighbors) should also be considered. Specific interior noise criteria (dba) and suggested building envelope STC ratings are determined by classifying site exposure into one of four categories as shown in table 1. A more complete version of this table is presented in the appendix of the FGI Guidelines, and as such is considered to be informative in nature (not part of the body of the document that is enforceable when adopted as code). The determination of which category a site falls into is made by evaluating factors such as the day-night average sound level (Ldn), the average hourly maximum sound level (dba) and the distance to nearby transportation noise sources. TABLE 1. FGI 2010 exterior site noise exposure categories Site Noise Exposure Category General Description Building Shell Minimum Composite STC (STC C ) A Minimal 35 B Moderate 40 C Significant 45 D Extreme 50 Proceedings of Meetings on Acoustics, Vol. 19, (2013) Page 2

3 Acoustic Finishes In order to foster an environment for patients rest and recovery, and a pleasant workplace for facility/medical staff, controlling the human activity noise (i.e. conversational speech, footsteps, dropped objects) and facilities equipment noise (i.e. HVAC, alarms, portable or fixed patient care equipment, service carts) is essential. Acoustically absorptive surfaces reduce reverberation and, therefore, sound levels at a distance from the sound source. The use of sound absorbing finishes in the base building (ceiling or walls acoustical panels) is a good way to address this issue. For this reason, the Guidelines have specific requirements regarding average room absorption in different types of rooms based on their functionality. In all cases, any material used must meet any applicable fire codes and infection control/cleaning requirements as defined by the facility. Design Room Sound Absorption Coefficient Rather than being prescriptive about specific kinds of finishes that should be used, FGI 2010 defines performance based upon the average sound absorption coefficient ( ). As each material in a room provides some sound absorption, the mean sound absorption coefficient shall be calculated from the sum of all boundary areas multiplied first by the sound absorbing performance of the material that constitutes the boundary. The noise reduction coefficient (NRC) is used for this calculation. Table 2 shows the minimum average sound absorption coefficients required by FGI TABLE 2. FGI 2010 design room sound absorption coefficients Space Minimum Private patient 0.15 Multi-bed patient 0.15 Corridor 0.15 Waiting area 0.25 Atrium 0.10 Physician s office 0.15 Treatment room 0.15 It can be noted that the minimum required sound absorption in waiting areas is higher as these areas tend to have more human activity noise. Atriums, typically having a larger volume with more boundary surfaces, will usually have a lower average absorption, though a minimum design room sound absorption of 0.10 should be sufficient. Room Noise Levels Noise from building mechanical systems is an important aspect of the acoustical environment and contributes to the overall comfort of both patients and facility staff. Different kind of equipment such as air handling units, terminal units (VAV boxes, diffusers), transformers, chillers, etc. are potential noisy sources that can emit sound through several paths (ducted-borne, structure-borne, breakout, etc.). Since several metrics exist to define noise levels in a room, FGI 2010 presents criteria for noise in interior occupied spaces based on functionality in terms of NC, RC(Neutral) and dba. These noise levels are as indicated in table 3. Proceedings of Meetings on Acoustics, Vol. 19, (2013) Page 3

4 TABLE 3. FGI 2010 design criteria for noise levels in interior spaces Space NC / RC(N) dba Patient rooms Multiple occupant patient care areas NICU Operating rooms Corridors and public spaces Testing/research lab, minimal speech Research lab, extensive speech Group teaching lab Doctor s offices, exam rooms Conference Rooms Teleconferencing Rooms 25 (max) 30 (max) Auditoriums, large lecture rooms While considering the FGI 2010 noise levels, one should keep in mind that upper limits may be higher than those allowed by ASHRAE [2] or ANSI [3] because facilities may be required to meet the FGI limits as a code requirement. As such, the FGI document is seen as a minimum design standard rather than the ideal. Some rooms such as laboratories and operating rooms will also need to account for practical minimum airflow requirements. Sound Isolation Performance of Constructions Interior wall and floor/ceiling constructions must provide adequate sound isolation, and the minimum required composite sound transmission class (STC C ) is based upon the use of adjacent spaces. Some of these required STC C values are presented below in table 4. A more complete listing is shown in the Guidelines. TABLE 4. selected FGI 2010 minimum sound isolation requirements (STC C ) Adjacency Combination Minimum STC C Patient room Patient room (wall same floor) 45 Patient room Patient room (floor-to-floor) 50 Patient room or Exam room Corridor (with entrance) 35 Patient room or Exam room Public space 50 NICU Corridor 50 Toilet room Public space 45 Consultation room Patient rooms 50 Public space MRI room 50 Speech Privacy It is noted that federal law requires facilities to safeguard patients' private information. Although FGI 2010 requires that spaces be designed to meet speech privacy goals, the specifics regarding those goals are left up to the design team. This allows some flexibility in the design based upon the needs and expectations of the specific facility. FGI 2010 allows for the use of one of four speech privacy rating methods (PI, AI, STI or SII). Building Vibration Although not referenced by LEED, vibration produced by building mechanical equipment, footfall, road and/or rail traffic and medical equipment should be considered in the design of any healthcare facility. FGI 2010 has some general guidelines to follow in this regard. Vibrations from Mechanical, Electrical and Plumbing Equipment Most building mechanical equipment generates vibrations that can be transmitted to the building structure. To avoid structure-borne transmitted sound, and to minimize impact on human comfort or sensitive equipment, all Proceedings of Meetings on Acoustics, Vol. 19, (2013) Page 4

5 rotating and vibrating components of the building systems should be isolated as recommended in the most current ASHRAE Applications Handbook [2]. Footfall induced vibrations Vibrations can occur from footfalls, and the velocity of these vibrations will depend upon the building structure (as well as the walker s weight, pace, etc. which are standardized in various evaluation methods). Therefore, the building structure must be designed so as to avoid footfall vibration levels in excess of the values shown in table 5. TABLE 5. FGI 2010 maximum limits on footfall floor vibration Space Footfall Floor Vibration Peak Velocity ( in/s) Patient Rooms and other Patient Areas 4000 Operating and other Treatment Rooms 4000 Administrative Areas 8000 Public Circulation 8000 Medical and laboratory instrumentation Hospitals and healthcare facilities are likely to have sensitive equipment (i.e. MRI, microscope) which require vibrations to be sufficiently limited to ensure proper functioning. To avoid malfunctions the building must be designed so that vibrations do not exceed the limits recommended by the equipment supplier. UPCOMING CHANGES FOR 2014 FGI GUIDELINES The FGI Guidelines are currently in a revision process in preparation for the publication of the 2014 version. Based upon public comments received on the 2010 version, changes have been proposed to better reflect the intentions of the FGI acoustical working group (AWG) while keeping in mind common constraints related to the construction and operation of healthcare facilities. Presented below are some of the changes that are expected in the 2014 edition of the Guidelines. We anticipate that future versions of LEED for Healthcare will reference the 2014 Guidelines. Façade insulation based on OITC and account for functionality of interior space The 2014 Guidelines will reference the Outdoor-Indoor Transmission Class (OITC) [4, 5] instead of the Sound Transmission Class (STC) for the minimum criteria for isolation performance of building façades. While acousticians in North America are very familiar with STC, and STC has historically been used for indoor-to-indoor transmission as well as for outdoor-to-indoor transmission, OITC was developed specifically to assess the noise isolation provided by a building façade. Interior spaces that are less sensitive to noise (stairways, corridors, atria) will be permitted to have a lower composite OITC rating. Suggested Sound Absorption in Operating Rooms Operating rooms have been shown to be excessively noisy spaces. A large number of simultaneous activities and alarms (alarm fatigue) can complicate speech communication and endanger medical staff s concentration at a time when they need it the most. Because of the increasing number of acoustical products suitable for use in operating rooms, FGI 2014 will suggest a minimum average sound absorption coefficient of 0.10 for operating rooms. As previously mentioned, any material used must also satisfy all infection control/cleaning requirements as defined by the facility. Proceedings of Meetings on Acoustics, Vol. 19, (2013) Page 5

6 Building Mechanical Systems Maximum Noise Levels Only FGI 2010 stated that noise levels from building mechanical systems must fall within the ranges shown in table 3. However, it makes little sense to enforce a minimum noise limit for mechanical, electrical and plumbing equipment. FGI 2014 will define maximum noise levels (with no minimum). Sound Isolation of Doors The composite sound transmission class (STC C ) required by FGI 2010 for patient, consultation and exam rooms adjacent to a corridor (including the door) is 35. This would typically require the use of a solid-core door with fullperimeter gasketing, including a drop seal. This type of door hardware may not be compatible with infection control and cleaning requirements. To overcome this issue, the performance objective has been assigned to the partition itself, excluding the door, and the use of full-perimeter gasketing will be left to the discretion of the facility. Speech Privacy Metrics The speech transmission index (STI), which is used for the assessment of intelligibility of public address and other sound reinforcement systems. will be replaced in FGI 2014 by the speech privacy class (SPC) [6] that was developed specifically for evaluating the degree of confidentially provided by a partition. Footfall Vibrations in Patient Rooms and Other Patient Areas It has been noted that the 4,000 in/s peak velocity limit for footfall vibration in patient rooms and other patient areas is generally too stringent and may require floor structures that are difficult to implement. The maximum limit on footfall vibration for these areas in FGI 2014 is to be increased to 6,000 in/s. ACKNOWLEDGMENTS The authors wish to gratefully acknowledge the help and support of the Health Guidelines Revision Committee (HGRC), the Facility Guidelines Institute (FGI) and the FGI acoustical working group (AWG), not only in the preparation of this paper but also in their continued efforts to maintain and revise the FGI Guidelines. REFERENCES 1. The Facility Guidelines Institute (FGI), Guidelines for Design and Construction of Health Care Facilities (American Society for Healthcare Engineering of the American Hospital Association, Illinois, 2010) 2. ASHRAE Handbook HVAC applications, Chapter 48, "Noise and Vibration Control," (American Society of Heating, Refrigerating and Air-Conditioning Engineers inc., Georgia, 2011). 3. ANSI/ASA S American National Standard Criteria for Evaluating Room Noise (American National Standards Institute, New York, 2008). 4. ASTM E Standard Guide for Field Measurements of Airborne Sound Attenuation of Building Facades and Facade Elements (ASTM International, Pennsylvania, 2010). 5. ASTM E Standard Classification for Rating Outdoor-Indoor Sound Attenuation (ASTM International, Pennsylvania, 2010). 6. ASTM E Standard Test Method for Objective Measurement of the Speech Privacy Provided by a Closed Room (ASTM International, Pennsylvania, 2010). Proceedings of Meetings on Acoustics, Vol. 19, (2013) Page 6

Acoustical standards and criteria documentation of sustainability in hospital design and construction

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