NOISE IS OFTEN AN UNWANTED STIMULUS to the body, and clear links have been established between prolonged exposure to noise and shorter life expectancy (Maynard & Moorhouse, 2009). Good acoustic design is often seen as simply controlling disturbance and maintaining privacy. In healthcare buildings, good acoustic design is of greater importance because it can affect the health and recovery of the patients using the building. High noise levels not only cause obvious effects like annoyance and sleep disturbance but also decrease the rate at which patients’ wounds heal and increase the likelihood of rehospitalization. Links have also been found between noise exposure of staff and increased levels of stress, fatigue, and emotional exhaustion (Anjali & Ulrich, 2007). This is in addition to the usual communication difficulties associated with any noisy environment.
With regards to privacy there are few environments where maintaining confidentiality is of such importance. Architects and designers in the US should be aware that it is a federal government requirement to ensure that healthcare organizations provide privacy for patient health information. This extends to any spoken information and so it becomes directly linked to the acoustic performance of the building.
8.2.1 Performance specifications
Healthcare buildings are often unique in their acoustic requirements due to the very nature of the building’s use. With high levels of mechanical and electrical services, controlling noise from the building becomes a particular issue. Much of the machinery and many tasks undertaken within healthcare buildings require controlled environments and this often extends to the control of noise and even vibration. Finally, providing privacy, confidentiality, and comfort are paramount but often conflict with the nature and use of the building.
The three key design goals for healthcare buildings are as follows:
controlling noise affecting patient and staff areas from either external noise sources or noise sources associated with the building,
providing partitions within the building that will ensure that confidentiality is maintained, as well as enhancing the control of possible noise disturbance,
providing suitable levels of control with regards to room acoustics without compromising clinical standards and performance.
Specific guideline levels for airborne sound insulation, ambient noise control, acceptable mechanical noise levels, and impact insulation requirements are detailed in Appendix B.
8.2.2 Sound insulation
With specific regards to sound insulation of partitions:
Locating rooms adjacent to one another that result in a minimum partition requirement of STC/Rw of 64 dB should be avoided.
For long-term health care facilities, e.g., residential care, performance specifications for walls and floors should be in line with local building codes/standards associated with separating partitions between dwellings.
It should be remembered that loud speech is not uncommon in treatment and consultation rooms, so good levels of acoustic insulation are of paramount importance if privacy is to be protected.
8.2.3 Controlling reverberation
Reverberation times are not commonly set as performance standards in healthcare buildings, due to often conflicting clinical requirements. It is considered good practice to ensure that:
An area equivalent to 80 percent of the floor should be covered with a material which provides a minimum NRC/absorption coefficient of 0.95.
Where this cannot be achieved the acoustic performance of any separating partition either side of the room should be increased by 3 dB.
For non-clinical areas, such as administrative or conference accommodation, guidelines for offices or educational buildings can be followed. Large open atrium or circulation areas are likely to require specialized acoustic design.
8.2.4 External noise limits
External areas used by staff, patients, or the public, such as accessible courtyards or landscaped areas, should be designed so that noise from services associated with the hospital does not exceed the existing daytime background level (LA90) or is not higher than LA90 50 dB, whichever is highest.
When considering the design of mental healthcare facilities, it is not unusual for the location to be chosen based on the tranquil nature of the existing environment. For outdoor treatment or relaxation areas, upper average noise limits of LAeq 50–55 dB during the daytime should be targeted.
Mechanical noise from the healthcare building should be controlled to a level which does not exceed LAeq 65 dB at the healthcare building façade and controlled to the pre-existing ambient noise level at the nearest noise sensitive location (e.g. dwelling), whichever is lowest.
Heliports should be located such that noise levels do not exceed LAeq 80 dB at the nearest noise sensitive location (e.g., dwelling). This assumes limited use of the heliport, i.e., fewer than three flights per day and no more than two flights during the nighttime period (10:00 PM–7:00 AM).
Emergency generator noise should be controlled to a level of LAeq 70 dB when measured at the façade of the healthcare building.
8.2.5 Internal doors and openings
Table 8.1 outlines suggested performance requirements for openings in internal walls, along with specification information and suitable locations. Doors to store cupboards and similar ancillary space would not require an acoustically rated door.
Table 8.1 Suggested performance requirements for openings in walls
Opening type | Suggested specification | Expected performance rating STC/Rw dB | Suitable location |
Standard door | Timber/metal door (light 44 mm @ 27 kg/m2) | 30 | • Staff offices, meeting rooms, etc. to corridors • Ancillary rooms to corridors |
Enhanced door | Timber/metal door (heavy 54 mm @ 29 kg/m2) | 35 | • Any medical treatment or consultation rooms to corridors or adjoining space |
Unrated vision panel | Single layer of glass in sliding frame | n/a | • Where visual and verbal communication is required, e.g., reception desk to waiting room |
Standard vision panel | 10 mm float glass/12 mm cavity/6.4 mm laminate glass | 40 | • Glazing set into a corridor wall or door frame between a medical treatment space and circulation space where some verbal communication is required |
Enhanced vision panel | 6mm float glass/100 mm cavity/4 mm float glass | 45 | • Where visual communication is required between a medical treatment space and another room, e.g., operating theater to observation gallery |
Optimum vision panel | 10 mm float glass/200 mm cavity/6 mm laminated glass (absorptive lining to window reveal between panes of glass) | 49 | • Between highly noise-sensitive areas and adjoining spaces, e.g., infant ICU and visitor gallery or treatment and observation rooms |
Rubberized seals are likely to be more clinically suitable than felt or brush seals.
Infection control designers should be consulted on the use of door seals.
It may not be possible to accommodate seals in doors which swing both ways or double doors, as compressible seals may require a rebate.
Drop-down seals are likely to cause issues for rooms where trolley access is required.
8.2.6 Maximum permissible noise levels
Noise intrusion from external sources and noise from other parts of the building should be controlled to below LAmax(f) 45 dB within rooms where patients may be sleeping, and LAmax(f) 50 dB for operating rooms.
8.3.1 Controlling external noise
Heliports: Figure 8.1 details the suggested positioning for a hospital heliport, assuming it is located on the ground. For heliports located on the roof of a hospital, it would be necessary to ensure that no treatment/consultant rooms, patient sleeping areas, operating rooms or noise-sensitive laboratory equipment is located on the floor directly below the heliport and any room within 20 ft (6 m) of the helipad. Where possible, heliports should be located on top of ancillary space such as mechanical rooms and as remote from the core healthcare activities as possible. Specialist guidance on façade and roof specifications should be sought for roof-mounted heliports.
1) Nearest dwelling or noise-sensitive location
2) Minimum slant distance between noise-sensitive location and helicopter
3) Helicopter takeoff flight path
4) Helipad
5) Hospital
6) Minimum standoff distance between heliport and hospital building
(see Figure 8.1)
8.1 Heliport location
Road and rail noise: It is advisable to ensure that any rooms specifically for the treatment or care of patients, along with any noise-sensitive rooms (e.g., operating rooms), are a minimum of 65 ft (20 m) from any road or railway line. Control of noise break-in to such areas will be reliant upon design; therefore it is likely that mechanical ventilation will be required as allowing for open windows for ventilation would not be an option. The general principles on building location and layouts outlined in Chapter 4 and Chapter 7 should be consulted.
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