Optimizing acoustic comfort in hospital sleeping wards: Parametric simulation of hospital envelope

Abstract

Environmental comfort, particularly acoustic comfort, plays a crucial role in patient satisfaction within healthcare facilities, especially in sleeping wards. This study aims to optimize hospital acoustic performance to meet recommended noise levels. It defines key acoustic parameters and uses computer simulations to develop solutions that minimize the impact of external noise sources. Results indicate that optimizing window placement and type, applying acoustic insulation treatments, and using multi-layered wall materials significantly reduce noise levels. The study emphasizes the importance of integrating acoustic comfort in hospital design to improve overall healthcare quality. It offers practical guidelines for intervention during the design phase of hospitals and provides valuable insights for architects, engineers, and policymakers to create acoustically optimized healthcare environments.

Keywords

acoustic comfort hospitals’ sleeping wards acoustic performance simulation program

Introduction

Sustainable architecture aims to create safe, eco-friendly, efficient, durable, and affordable buildings. As sustainability gains importance, evaluating how people feel in public spaces like hospitals is crucial for ensuring both environmental responsibility and occupant comfort.¹ The “healing environment” concept is essential worldwide, linking hospital design to improved care and faster patient recovery.² This approach, often referred to as “healing by design,” links evidence-based design strategies such as acoustic control, daylight optimization, and access to nature to measurable improvements in patients’ psychological and physiological recovery.³ Healing by design highlights the role of architectural and environmental design factors such as acoustics, light, and spatial organization in supporting patients’ healing and overall comfort.⁴

Therefore, the hospital’s sleeping unit is one of the most sensitive places and needs attention because it is where patients are located throughout their stay in the hospital. Therefore, all comfort standards must be provided to them, especially acoustic comfort, to achieve calm and get enough sleep and thus recover faster.⁵ The design of the ward itself plays a major role in achieving this in terms of the design of the facades and windows, the larger number of beds in the room relative to its area, the distribution of other spaces in the ward such as the nursing area, the doctor’s room, the instrument room, and its relationship with the patients’ bedroom.⁶

Noise pollution is an old problem. It is not limited to saying that the past is quieter and the present is louder. Noise has always been a special problem for cities. There is also the fact that noise is a forgotten environmental problem, and due to history, it has not been treated with the same force with which other pollutants were dealt with. Therefore, these problems related to noise, which have been discussed for hundreds or even thousands of years, are still subject to debate.⁷ Although the problem of noise has evolved with technological and cultural changes, its essence remains the same. Today, noise affects more people due to urbanization, with hospitals in cities exposed to various types of external and internal noise. Consequently, it is crucial for patients to experience comfort during their stay to support faster recovery.⁵

There are studies in Palestine that talk about acoustics in general, and the study by Abdel-Raziq et al. dealt with measuring acoustics in the external areas of the city of Nablus. The study presented some recommendations to reduce external noise, including planting trees, placing barriers, and increasing setbacks in residential areas.⁸ Another study also touched on acoustics in some schools in Palestine and around the world to measure the academic performance of students through a questionnaire.⁹

The El-Afifi study also addressed the extent of nurses’ knowledge in a hospital in Ramallah, Palestine, about the impact of noise on patients. It was found through the questionnaire that nurses need awareness and educational programs about noise problems. The study recommended investigating the issue of sound pollution in the rest of the hospitals in Palestine.¹⁰ There is another study by Sadeq that dealt with the effect of noise on an increase in blood pressure by measuring noise levels on the one hand and blood pressure on the other hand. The study recommended some theoretical proposals, such as reducing the noise emitted by phones and using absorbent materials, and that designers should consider the resulting noise before designing hospitals.¹¹

Previous studies highlight the impact of noise on patients and workers, but there is a lack of research on practical solutions tested through simulations within internal spaces. Some studies have focused on external factors like tree placement and double-glazed windows. However, there is a significant research gap in addressing applicable solutions for internal noise. This research aims to explore the relationship between patient healing and acoustic performance by analyzing hospital sleeping wards and suggesting strategies for acoustic comfort.

Previous studies have demonstrated the influence of noise on patients and healthcare staff and explored various mitigation measures, primarily focusing on external factors such as façade design and glazing systems. However, fewer studies have investigated how interior acoustic solutions, evaluated through simulation-based approaches, can enhance patient comfort within hospital wards. The present study contributes to this growing field by assessing the acoustic performance of internal design strategies and their potential role in supporting patient recovery.

Similar approaches have been adopted in recent literature. For example, Secchi et al. analyzed the acoustic comfort in hospital maternity rooms using predictive software and found that simulation-based results align closely with field measurements.¹² Secchi et al. examined how bedroom layout and façade design influence acoustic comfort through parametric simulation.¹³ Xie and Kang also applied computational models to study sound field distribution and reverberation patterns in single-bed hospital wards, providing valuable validation data for this type of analysis.¹⁴

Building on these insights, the current study employed RAP-ONE II simulation software to evaluate various internal design configurations and their effects on acoustic performance. to identify design strategies that can meaningfully improve patient comfort and support recovery processes.

Representing sound levels

Sound is typically measured using the decibel (dB) scale, which represents the ratio between two pressure levels. As a logarithmic scale, it simplifies a wide range of values into a more manageable form, making it easier to analyze variations in noise levels effectively.¹⁵The use of A-weighting has become the de facto accepted descriptor for environmental noise, and numerous studies have shown that A-weighted sound levels provide an acceptable correlation with human response to different noise sources¹⁶

The decibel scale may be unfamiliar to some, but we typically encounter noise levels between 30 and 100 dB(A) in everyday life. Noise levels below 35–40 dB(A) are generally needed for a good night’s sleep; a busy office may register around 60 dB(A), while a footpath beside a busy road might experience approximately 75 dB(A).¹⁷ Figure 1 illustrates some typical noise levels.

Figure 1.

The logical framework for the methodology.

Inpatient and healing environment

The term “healing environment” is used to describe the conditions that have affected the medical community, comprising staff, patients, and visitors.^3,4 Vital elements include air quality, noise control, thermal comfort, privacy, and lighting. It is essential for patients and medical workers, defined as a comprehensive setting, both physical and non-physical, crafted to facilitate recovery and the healing process.^18,19

The healing environment promotes patient recovery and increases employee productivity and performance.¹⁹ Designing hospitals is a complex task that requires attention to several functional, social, and psychological aspects. Therefore, providing the appropriate internal environment for the patient is one of the design priorities. Hospitals in general are stressful places for patients and workers because of their association with fear, pain, and feeling disturbed by noise, smells, etc.²⁰

Noise impact on patients

One of the most distressing elements in the hospital environment is noise pollution,²¹ which is a stressful experience for patients. During their stay in the hospital, they need rest and adequate sleep.¹² It is known that high noise levels in health facilities lead to several health problems, including the inability to sleep adequately, increased stress, delayed recovery, increased insomnia, increased breathing and heart rates, high blood pressure, headaches, hearing loss, increased Cholesterol level in the blood, and narrowing of blood vessels.²² According to previous studies, increased hospital noise levels are associated with shorter patient stays, as many leave prematurely in search of quieter environments for recovery.²³ A study conducted in a university hospital in Bologna analyzed noise sources and identified staff conversations, medical equipment, and ventilation systems as major contributors. The findings revealed that noise levels often exceed WHO recommendations, with speech being a dominant source, highlighting the need for targeted noise reduction strategies to enhance patient well-being and hospital efficiency.²⁴

Noise impact on staff

Healthcare workers suffer from the same exposure to noise as patients so they are exposed to the same health risks previously mentioned, and noise greatly affects behavior and work efficiency.²² According to arousal theory, there is an optimal level of arousal for efficient performance. Noise can enhance performance if arousal is too low, but it can hinder performance if arousal is already high. Complex or repetitive tasks are best performed in quiet environments, while easy tasks may benefit from some noise.²⁵ The type of job is more crucial than the type of noise. Noise generally hinders performance on difficult tasks but enhances performance on simple tasks. However, if noise levels exceed those needed for optimal arousal, workers can become agitated and less productive, with agitation persisting even after the noise subsides.²⁶

Acoustics in hospitals

Acoustic conditions in hospitals are essential for enhancing patient well-being and supporting the healing process. Implementing effective acoustic design with eco-friendly and biocompatible materials helps reduce noise pollution, minimize stress, and improve communication between patients and healthcare staff.²⁷ To ensure the patient’s well-being, the acoustical conditions in hospitals are important. This covers the following topics: supporting patients’ acoustical privacy; helping patients’ psycho-physical recovery by enabling them to sleep or rest comfortably; and supporting patients’ affective processes by using pleasant sounds that may inspire emotions of calm and well-being.^28,29 The following factors should be taken into consideration:

- Distribution of hospital spaces that call for silence in proper zones and placing noisy places like waiting areas, visiting rooms, and wards away from them.³⁰

- Using internal walls and sound-absorbing materials, and the noise generated from medical equipment, ventilation systems, and sanitary water systems, the movement of people and healthcare equipment is a priority.³¹

- Special attention must be paid to the connection between the façade and the dividing walls and floors to prevent leakage and sound transmission.³⁰

- The acoustic performance of windows is the primary concern. Although it might be challenging to achieve effective façade sound insulation when roller shutters are employed, in this situation, employing absorbing shading systems could improve acoustic performance.³²

- Paying close attention to how well technical installations, pipes, and air conditioners are soundproofed.³⁰

Countries have various indicators and limits for hospital acoustics. Some focus on sound insulation between bedrooms, while others set criteria for walls between bedrooms and corridors. A comparative study by Rasmussen et al. showed that countries differ in their acoustic regulations for hospital bedrooms, with some emphasizing sound insulation between bedrooms and others setting limits between bedrooms and corridors.³¹ The World Health Organization recommends a maximum intermittent noise level of 45 dB at night and an average indoor sound level of no more than 30 dB over 8 h.^12,33

Materials and methods

This study uses parametric analysis and computer simulation to evaluate the state of the hospitals and establish a guideline to improve the acoustics performance in the hospitals. The first step after analyzing the state of the art for the hospital’s acoustics design was defining the acoustics design parameters and then comparing it with the international standards, performing the simulation, and proposing the solution to optimize the acoustics performance, as seen in Figure 1.

Parameters affecting acoustic design

Window design plays a crucial role in sound insulation, often being less soundproof than other building components. Recent advances have improved windows’ noise isolation through multiple layers and materials like argon or krypton gas, which enhance insulation and reduce external noise. This results in a quieter internal environment.³⁴ It should be noted that hospitals in many urban environments are often located in city centers or near busy commercial areas, making them more exposed to external noise from traffic and surrounding markets. Studies indicate that these elevated noise levels negatively affect both patients and hospital staff, highlighting the importance of enhancing the building envelope’s acoustic performance, particularly windows, to reduce the transmission of external noise into patient rooms and ensure acoustic comfort.^35,36

Acoustic solutions fall into two categories: soundproofing, which prevents sound from entering or leaving a space, and acoustic treatment, which improves or optimizes sound quality.

Recent studies have highlighted the effectiveness of eco-friendly and biocompatible materials in improving acoustic comfort in healthcare settings. These materials not only reduce noise pollution but also enhance patient well-being and safety.²⁷ Acoustic solutions in healthcare buildings can be categorized into technical and non-technical interventions. Technical interventions include measures that improve the acoustic performance of building elements, indoor sound quality, and noise source reduction. These may involve design strategies such as soundproofing, which prevents sound transmission between spaces, and acoustic treatment, which enhances sound quality within rooms³⁷ In this study, the focus is mainly on these technical solutions.

It is important to distinguish between sound insulation, which prevents the transmission of sound through walls and facades, and sound absorption, which reduces echo and reverberation inside the room. In this study, the materials were selected primarily for their sound insulation performance, while some of them can also contribute to sound absorption when installed with proper wall assemblies. And these materials are the following:

- Mineral wool is considered one of the best sound-insulating materials for finishing. It is an inorganic, non-shiny material and has high noise-blocking capabilities. It is used for lining walls, as it reduces the intensity of noise and prevents sound echoes.³⁸

- Glass wool is an insulating material made from sintered glass fibers like wool fibers. It is produced in the form of sheets or wrapped strips with thermal and sound insulation properties and works to absorb sound well.^39,40

- Acoustic Treatment Systems (ATS) are ready-to-install panels that are pre-manufactured in different sizes and colors and are the best soundproofing and echo-eliminating materials.⁴¹

- An Acoustic Treatment System (ATS) relies on three main components that work together to improve sound absorption. If the system is built inside a wall, it also improves sound insulation. In this study, the system was as follows:

- Core: Consisting of polyurethane foam (PU foam), which is responsible for isolating sound energy, especially high frequencies.⁴²

- Facing Layer: Typically, perforated panels or acoustic fabric allow sound to pass into the core.

- Air Gap: Left behind the panel to improve low-frequency absorption and increase overall system efficiency.

- Polyester panels, which are used to line ceilings and walls, are easy to install and use, come in several different colors, and effectively reduce sound and echo noise.⁴³

Walls are one of the most important means of blocking noise, and its efficiency depends on its density, the material from which the wall is built, and its thickness. It is important to notice the effect of orientation on noise, facades oriented parallel to the road are most influenced by traffic noise. This can be treated by changing the shape and material to absorb and block noise. In addition to technical measures, non-technical or organizational solutions can also contribute to better acoustic comfort. For example, modifying the shape and material of interior elements can help absorb and block noise. Landscape features, including trees and green areas, contribute to reducing the impact of outdoor noise on rooms inside the building. Bed location is also an important factor; beds located near windows are more affected by surrounding noise, while those near corridors are influenced by interior noise. Landscape including trees and green areas contribute to reducing the impact of noise on the rooms inside the buildings. Bed location is also an important factor; beds located near windows are more affected by surrounding noise. Also, beds near the corridors are more influenced by interior noise³⁷

International standards for hospital acoustics

The U.S. Noise Control Act (NCA) of 1972 was the first major noise regulation. The World Health Organization (WHO) later highlighted the health impacts of noise, identifying it as a major public health issue in 2011. The WHO has since made various recommendations on safe noise exposure levels and, in 2018, established environmental noise rules for public safety in Europe.⁴⁴

The World Health Organization (WHO) aims to improve global healthcare and address noise-related concerns. According to the “Guidelines for Community Noise,” hospital spaces should have indoor noise levels of 30 dBA at night and no more than 40 dBA for night sound events. For daytime, 35 dBA is recommended. In inpatient treatment rooms, noise should be kept below 30 dBA if possible, with a maximum of 35 dBA.³³ External areas around hospitals should not exceed 55 dBA.^{22,33 ⁴⁵} Table 1 shows standards from the World Health Organization.

Table 1.

Standards from the World Health Organization.⁴⁵

Specific environment	Critical health effects	dB(A)	Time base (hours)	L_Amax dB(A)
Hospitals, ward rooms, indoor	Sleep disturbance, night-time	30	8	40
	Sleep disturbance, day and evening	30	16	-

Computer performance simulation

The study adopts a sequence of iterative computational simulations using a model of a 30 m² square-shaped sleeping room, to investigate the impact of different parameters on noise to achieve the optimal value of each parameter to reach the standard noise value. Its dimensions were based on standard Palestinian laws for sleeping rooms.⁴⁶ Figure 2 shows the model that was designed as a typical sleeping room.

Figure 2.

The designed model for the computer simulation.

The Rap One II program has been used for acoustic comfort optimization. It is a user-friendly simulation tool for managing and analyzing room sound. It helps acoustic engineers and consultants by quickly and accurately determining sound level based on external noise value and identifying areas for internal noise measurement. Therefore, the simulations were carried out using the RAP-ONE II software, which applies a pyramid tracing acoustic model to calculate the propagation of sound within enclosed spaces. This method traces energy beams (pyramids) emitted from each source and computes their interactions with room surfaces according to their absorption and transmission characteristics.

Unlike analytical standards such as EN ISO 12354-3, which estimate façade insulation performance independently of geometry, RAP-ONE II considers the spatial configuration of the room and the position of façade openings, allowing for a more detailed assessment of how sound energy is distributed inside the space. In all simulations, typical acoustic performances were determined for all materials used and included in the simulations based on manufacturer data. The materials, absorption coefficient values, and sound transmission loss values were selected from the software’s built-in library. If there are any materials not defined in the library, they can be added manually and their values entered. The software also takes into account the direction and angle of sound incident on window and wall surfaces, which affects the effective sound energy entering the room.⁴⁷ The model was entered into the program to start the optimization process. The optimization process evaluated six parameters (window height, window-to-wall ratio, wall thickness and materials, and window type) sequentially. The optimal result from each parameter was used as input for the next, allowing for a comprehensive assessment of their combined effects. Figure 3 shows the method followed for each variable to find the optimal values for each one of them through simulation. Although RAP-ONE II does not require the direct input of physical parameters such as density or airflow resistance, the materials were selected based on their typical acoustic properties. For example, mineral wool and glass wool generally exhibit densities between 40 and 80 kg/m^³ and high sound absorption coefficients (α ≈ 0.8–0.9 at mid-frequencies), while polyester panels exhibit intermediate absorption efficiency. These values are provided only to justify the choice of materials, and not as direct inputs to the simulation.⁴⁸

Figure 3.

Steps of the methodology in the optimization process for simulation.

Results and discussion

To optimize the acoustics comfort, the computer simulation has been done for different parameters (window height above the floor, window-to-wall ratio, external wall thickness and materials, internal wall thickness and material, window type, and double skin façade). The parametric design analysis was performed for each variable and the optimum value for each parameter is used as a fixed value when evaluating the next parameters. For the outdoor noise level, the three models used in the simulation are based on the field measurements of outdoor noise in the urban environment. These models are presented as follows:

- Model 1 is used for external noise ⩾80 dBA,

- Model 2 for 65–79 dBA, and

- Model 3 for 55–64 dBA, where the minimum value of 55 dBA is based on WHO guidelines.

Effects of window height

Simulation experiments tested window height in 25 cm increments, using typical stone course heights based on local material, with other variables fixed as in Table 2. Five window height scenarios have been simulated, as it is explained in Figure 4. This approach evaluated the impact of different net window heights from the floor on the acoustic environment.

Table 2.

The fixed variables on window height in the simulation models.

Parameters	Values
Window-to-wall ratio	30%
External wall thickness	0.3 m
Exterior wall materials and thickness of each layer	Stone (0.05 m)Concrete (0.15 m)Air (0.03 m)Brick (0.07 m)
Interior wall thickness	0.14 m
Interior wall materials and thickness of each layer	Plaster (0.02 m)Brick (0.1 m)Plaster (0.02 m)
Window type	Double glazing and vacuum between the two layers
Use techniques and double skin on the façade	No

Figure 4.

Simulation cases for the models with the change of window height.

The simulation results in Table 3 indicate that the optimal window heights were 1 m for the model 1, 0.75 m for model 2, and 0.5 m for model 3. The attached results show that the change in noise values due to the change in the height of the window on the facade is considered small and relatively close, but this change that appeared during the simulations should be taken into account. where decreasing the window height in each model increased noise levels, so these values were adopted as the optimal heights for each model of the outdoor noise.

Table 3.

The simulation results for the window height from the floor.

The height of the window from the floor (m)		0.5	0.75	1	1.25	1.5
Highest noise value inside the room near the window (dBA)	Model 1	79	77	75	75	74.5
	Model 2	77	75	75	74.7	74.5
	Model 3	64	64	64	63.8	63.5

Window-to-wall ratio

The window-to-wall ratios of 10%, 20%, 30%, 40%, and 50% as shown in Figure 5, were tested using computer simulation to determine the optimum ration for acoustic performance, with all other variables kept constant as in Table 2 above.

Figure 5.

Simulation cases for the models with the change of window-to-wall ratio.

The simulation results shown in Table 4 confirm the direct relationship between window-to-wall ratio and noise levels. Increasing the window-to-wall ratio will increase the noise level. The optimal ratios were 20% for the first model, 30% for the second, and 40% for the third. It is worth mentioning that the optimum ratio has been chosen based on the maximum possible ratio that also gives a low dBA.

Table 4.

The simulation results for the window-to-wall ratio.

Window to wall ratio (%)		10%	20%	30%	40%	50%
Highest noise value inside the room near the window (dBA)	Model 1	74	74	75	75.5	76
	Model 2	72.7	73	73	74.5	75
	Model 3	63.6	63.8	64	64.3	65

External wall thickness and materials

Different wall thicknesses (30, 40, and 50 cm) were tested with various insulation types: mineral wool, glass wool, ATS (PU foam), and Polyester panels, The thicknesses between 30 and 50 cm were chosen to balance sound insulation and cost, and to help understand the relationship between thickness and noise, taking into account the available thicknesses of local materials. as shown in Figure 6. Sound-absorbing materials were not used, focusing instead on sound insulation, which effectively prevents sound transmission between indoor and outdoor spaces.

Figure 6.

Simulation cases for the models with the change of external wall thickness and materials.

The simulation results in Table 5 show that mineral wool is the most effective insulation for noise reduction. The optimal wall thicknesses are 50 cm for the first model, 40 cm for the second, and 30 cm for the third, with the difference between 30 and 40 cm in the third model being only 1 dB, considered negligible.

Table 5.

The simulation results for the change of the external wall thickness and materials.

External wall thickness			Mineral wool	Glass wool	ATS PU foam	Polyester panels
Highest noise value inside the room (dBA)	Model 11	30 cm	70	72	74	73
		40 cm	66	68	72	70
		50 cm	64	67	71	69
	Model 12	30 cm	69	71	73	72
	Model 12	40 cm	64	66	70	68
	Model 13	30 cm	59	62	64	60
		40 cm	58	61	63	59

Internal wall thickness and material

The interior wall is a key important factor to reduce noise, requiring at least 20 cm thickness with sound insulation. Simulations tested four insulation types: mineral wool, glass wool, ATS (PU foam), and Polyester panels. Figure 7 shows the simulation cases for the Internal wall thickness and material. The figure shows two scenarios for the interior partition. The first is composed of two concrete block layers and 7 cm sound insulation, and the second is composed of concrete block, sound insulation, and plasterboard.

Figure 7.

Simulation cases for Internal wall thickness and material.

The results shown in Table 6 demonstrate that mineral wool is the best insulation for noise reduction. The difference between the first and second scenarios is just 1 dB, so the lowest noise value was chosen as the optimal scenario for each model.

Table 6.

The simulation results for the Internal wall thickness and material.

Interior wall with a thickness of 20 cm			Mineral wool	Glass wool	ATS PU foam	Polyester panels
Highest noise value inside the room (dBA)	Model 1	Scenario 1	61	62	64	63
	Model 1	Scenario 2	60	62	64	63
	Model 2	Scenario 1	59	60	63	62
	Model 2	Scenario 2	60	61	64	63
	Model 3	Scenario 1	55	56	58	55
	Model 3	Scenario 2	54	56	57	54

Window type

Windows are key elements of building facades, connecting the interior with the exterior environments, but also affecting the transmitted noise level. Three types of glass windows were tested: single, double, and triple glazing, with variable glass thicknesses (0.4, 0.7, and 1 cm), space thicknesses (0.6, 1, 1.5, and 2 cm), and different gases in the cavity (krypton, argon, air, vacuum) filling the gaps as shown in Figure 8 and Table 7, Where the materials library used in RAP-ONE II is based on sound transmission loss values experimentally verified by the software developers. These values encompass the realistic performance of double and triple glass across the frequency range, including the decrease caused by the resonance phenomenon between the mass and the spring at approximately 200 Hz. Therefore, the effect of this phenomenon is considered in the acoustic modeling, although it is not shown separately due to the software’s reliance on octave band analysis rather than narrow-band analysis.⁴⁷

Figure 8.

The simulation cases for the window type.

Table 7.

The results of transmitted noise level for optimizing glazing types.

Model 1
Double glass					Triple glass
(Thickness of the glass) 0.4 cm
Thickness of the space (cm)	Argon	Krypton	Air	Vacuum	Thickness of the space (cm)	Argon	Krypton	Air	Vacuum
0.6	60	59	65	60	0.6	56	54	56.5	56
1	59	58	63	60	1	55.5	53.6	56	55.3
1.5	59	57.5	62	59.5	1.5	55	53.3	56	55
2	58.5	57	62	59	2	54	53	55.5	54.5
(Thickness of the glass) 0.7 cm
0.6	58	57	61	59	0.6	53.7	52.8	55	54
1	57	56.5	61	58.5	1	53.5	52.5	54.5	53.5
1.5	57	56	60	58	1.5	53	52	54	53
2	57	56	60	58	2	52.8	52	54	53
(Thickness of the glass) 1 cm
0.6	56.7	55.8	59	57.5	0.6	51.5	51.5	53.3	52.8
1	56.5	55.5	58	57	1	51	51	53	52.5
1.5	56.5	55.3	58.5	56.8	1.5	51	50	52.8	52
2	56.3	55	57	56.5	2	50.5	50	52.5	52
Model 2					Model 3
Double glass
(Thickness of the glass) 0.4 cm
Thickness of the space (cm)	Argon	Krypton	Air	Vacuum	Thickness of the space (cm)	Argon	Krypton	Air	Vacuum
0.6	58	58.5	63	59	0.6	54	53	58	54
1	57	58	62	59	1	53	53	58	54
1.5	56.5	57	62	58.5	1.5	52	52	57	53
2	55	56.5	61	58	2	52	51	56	52.5
(Thickness of the glass) 0.7 cm
0.6	55.5	56	62	58	0.6	52	50	56	53
1	54	55.5	61	57	1	51	50	55	52
1.5	53	55	60	56.5	1.5	51	49	55	52
2	52.5	54	59	55	2	50	49	54	51
(Thickness of the glass) 1 cm
0.6	51	53	59	56	0.6	52	50	56	53
1	50	52	58	55	1	51	50	55	52
1.5	50	51	58.5	54.5	1.5	51	49	55	52
2	49.8	51	57	53	2	50	49	54	51

The simulation results shown in Table 7 highlight that single-layer glass is rejected for all models because of the high noise level transmitted. Krypton and argon were selected as effective fillers for the cavity between glass layers. Trible glazing with 1 cm glazing thickness and 1.5 cm cavity thickness (krypton filled) was the best choice for model 1 for optimal noise reduction, while double glazing with 1 cm glazing thickness and 1.5 cm cavity thickness (Argon filled) was sufficient for model 2 and double glazing with 0.7 cm glazing thickness and 1 cm cavity thickness (krypton filled) for model 3.

Double skin façade

The idea of the double skin, as recommended in previous studies as Miller’s study⁴⁹ was assessed in this study for its effectiveness to improve acoustic performance. Studies have shown that the external facade plays a crucial role in controlling noise. Increasing attention to its design and the materials used in its construction enhances noise level management.⁵⁰ This concept was further developed, as shown in Figure 9, to determine the extent of its success. It is worth noting that the basic principle on which the system is based is (mass spring mass), where each wall layer is a mass. The thicker the space between the two walls, the less sound transmission at medium and low frequencies, and to limit the transmission of high frequencies, the second wall of the system was perforated, and sound-insulating materials were added within the perforated wall. When this system is entered into the simulation program, the program takes into account the resonance frequency limits resulting from the air gap.

Figure 9.

The materials of the double skin.

Distances between the double skin and the external wall (wall cavity) were tested for the following values (60, 80, 100, and 120 cm). The perforated external layer of the double skin was chosen because of its visibility. Simulations tested different openings of the perforated layers as follows: lengths (10, 15, and 20 cm) with a fixed width of 25 cm. Figure 10 shows the shape of the perforation in the double skin.

Figure 10.

The double-skin perforation technique.

The results in Table 8 show that the ideal distance for the double skin from the wall (wall cavity) is 1 m for models 1 and 2, and 80 cm for model 3. The optimal perforated space lengths were 10 cm for model 1 and 15 cm for models 2 and 3.

Table 8.

The simulation results for the distance of the double skin and the length of the perforated.

The distance from the wall and the double-skin cm		60	80	100	120
Highest noise value inside the room (dBA)	Model 1	46	44.5	43	43
	Model 2	45	44	43	43
	Model 3	42	41	41	40.7
The length of the perforated (cm)		10	15		20
Highest noise value inside the room (dBA)	Model 1	42	44		45
	Model 2	44	44		45
	Model 3	42	42		44

Simulations were also conducted to determine if the double skin should cover the entire facade or just certain areas. Table 9 shows that the first model needs full double skin coverage for 35 dBA noise reduction, the second model requires 75% coverage, and the third model needs 50% coverage.

Table 9.

The simulation results for the percentage of coverage.

Percentage of double-skin coverage of the external wall		100%	75%	50%	30%
Highest noise value inside the room (dBA)	Model 1	35	38	40	41
Highest noise value inside the room (dBA)	Model 2	35	36	39	41
Highest noise value inside the room (dBA)	Model 3	35	36	36.5	40

Conclusion

The optimization results show a clear link between acoustics design parameters and noise levels, with optimal values identified for each. For the three identified groups of outdoor noise: 80 dBA and above, 65–80 dBA, and 55–65 dBA the study provided optimum acoustics design values for different parameters affecting acoustics design performance. Future hospitals’ designs should consider these models and the urban planning of the area to incorporates the most appropriate solutions as shown in Table 10. The external noise values listed in the table are based on the three simulation models. The internal noise values were set close to the upper limit of the external noise range for Models 2 and 3, while for Model 1, they were taken near the lower limit. During the simulation, the external noise levels for Model 1 exceeded 95 dBA; therefore, the lower limit was selected in model 1, and the upper limit was selected in model 2,3 to represent a worst-case scenario for the analysis. All models meet the WHO standards for hospital bedroom noise levels.

Table 10.

The difference between the three models.

The final noise value internal (with improvement from the parametric optimization)	The initial noise value internal (without improvement)	External noise value dBA (based on the three models)	The models/values
35 dBA	79 dBA	Value ⩾80	Model 1
36 dBA	77 dBA	65⩽ value <80	Model 2
36.5 dBA	64 dBA	55⩽ value <65	Model 3

By implementing the parametric design analysis and acoustics computer simulation, the study provided the optimization strategies for a comfortable acoustics environment. Also, by defining key acoustic design parameters and comparing them with international standards, particularly those set by the World Health Organization, the study has established a clear approach to optimize hospital acoustics. The simulated parameters such as windows height and type, wall thickness and materials, and insulation materials proved to have a significant effect on the acoustic comfort, and the optimization of those parameters will have a significant effect on hospitals acoustic performance. Additionally, the adoption of double skin facades demonstrated measurable improvements in noise reduction, with coverage tailored to specific noise exposure levels.

The underscored findings align with international acoustic standards. This guideline for acoustic optimization can serve as a reference for healthcare facilities aiming to create quieter, more therapeutic environments. Future studies could expand on this work by applying the simulation methods to other hospital room configurations or testing additional materials for enhanced sound insulation.

Finally, the study recommends the following for optimum acoustics performance:

- The integration of the developed models into future design processes.

- Planting trees in the outdoor courtyards around hospitals and conducting greater research on the percentage of vegetation cover necessary to reduce external noise.

- The study recommends additional studies to explore the effectiveness of shrubs on the outer double skin in reducing noise infiltration and enhancing the performance of the double skin through simulation.

Footnotes

ORCID iDs

Raneem Alqwasmi

Abdelrahman Halawani

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

References

Ahmad

Verma

Kamal

MA.

Emerging trends in green healthcare building design of Saudi Arabia: a sustainable approach, Vol. 44. Library of Progress-Library Science, Information Technology & Computer, 2024.

Jongerden

Slooter

Peelen

, et al. Effect of intensive care environment on family and patient satisfaction: a before-after study. Intensive Care Med 2013; 39: 1626–1634.

Mahmood

Tayib

AY.

Healing environment correlated with patients’ psychological comfort: post-occupancy evaluation of general hospitals. Indoor Built Environ 2021; 30: 180–194.

Feng

Liu

, et al. Sustainable healing and therapeutic design driven well-being in hospital environment. Buildings 2024; 14: 2731.

de Lima Andrade

da Cunha E Silva

de Lima

, et al. Environmental noise in hospitals: a systematic review. Environ Sci Pollut Res 2021; 28: 19629–19642.

Evaluation of a sustainable hospital design based on its social and environmental outcomes. Unpublished master thesis, Presented to the Faculty of the Graduate School of Cornell University, 2011.

Schwartz

Discord: the story of noise by Mike Goldsmith (review). Technol Cult 2013; 54: 656–657.

Abdel-Raziq

Zeid

Seh

Noise measurements in the community of Nablus in Palestine. Acta Acust United Acust 2000; 86: 578–580.

Baba

Shahrour

Baba

Indoor environmental quality for comfort learning environments: case study of Palestinian school buildings. Buildings 2024; 14: 1296.

10.

El-Afifi

ElAwady

Awadalla

, et al. Knowledge, attitudes and practices of nurses towards noise in a public hospital in Palestine. J Environ Sci 2022; 0: 0–87.

11.

Sadeq

RME.

The effect of noise pollution on arterial blood pressure and pulse rate of workers in the hospitals of Nablus City-Palestine. 2010.

12.

Secchi

Setola

Marzi

, et al. Analysis of the acoustic comfort in hospital: the case of maternity rooms. Buildings 2022; 12: 1117.

13.

Secchi

Amodeo

Marzi

, et al. Analysis of bedroom distribution layouts to improve acoustic comfort in hospital wards. In: Proceedings of forum acusticum 2023, pp.1-6. European Acoustics Association.

14.

Xie

Kang

Sound field of typical single-bed hospital wards. Appl Acoust 2012; 73: 884–892.

15.

Katalin

Á.

Studying noise measurement and analysis. Procedia Manuf 2018; 22: 533–538.

16.

Knauert

Jeon

Murphy

, et al. Comparing average levels and peak occurrence of overnight sound in the medical intensive care unit on A-weighted and C-weighted decibel scales. J Crit Care 2016; 36: 1–7.

17.

Ueda

Tanaka

What is this sound in decibel? - we tried to determine students’ comprehension of sound levels, online ver. International Association for Development of the Information Society, 2020.

18.

Amleh

Halawani

Haj Hussein

Simulation-based study for healing environment in intensive care units: enhancing daylight and access to view, optimizing an ICU room in temperate climate, the case study of Palestine. Ain Shams Eng J 2023; 14: 101868.

19.

Rafeeq

Mustafa

FA.

Evidence-based design: the role of inpatient typology in creating healing environment, hospitals in Erbil city as a case study. Ain Shams Eng J 2021; 12: 1073–1087.

20.

Vahedian-Azimi

Bashar

Khan

, et al. Natural versus artificial light exposure on delirium incidence in ARDS patients. Ann Intensive Care 2020; 10: 15–23.

21.

Tahvili

Waite

Hampton

, et al. Noise and sound in the intensive care unit: a cohort study. Sci Rep 2025; 15: 10858.

22.

Wiese

CH.

Investigation of patient perception of hospital noise and sound level measurements: before, during, and after renovations of a hospital wing. Master thesis. University of Nebraska, Lincoln, 2010.

23.

Xun

Liu

Sun

, et al. Impact of hospital ward acoustic design on postoperative recovery of patients with acute myocardial infarction. Noise Health 2025; 27: 534–544.

24.

Cingolani

De Salvio

D’Orazio

, et al. Clustering analysis of noise sources in healthcare facilities. Appl Acoust 2023; 214: 109660.

25.

Zio

Prognostics and Health Management (PHM): where are we and where do we (need to) go in theory and practice. Reliab Eng Syst Saf 2022; 218: 108119.

26.

Eijkelenboom

Bluyssen

PM.

Comfort and health of patients and staff, related to the physical environment of different departments in hospitals: a literature review. Intell Build Int 2022; 14: 95–113.

27.

del Rosario-Gilabert

Carbajo

Hernández-Pozo

, et al. Eco-friendly and biocompatible material to reduce noise pollution and improve acoustic comfort in healthcare environments. Buildings 2024; 14: 3151.

28.

Adams

Harrison

Schembri

, et al. The silent threat: investigating sleep disturbances in hospitalized patients. Int J Qual Health Care 2024; 36: mzae042.

29.

Rossetti

Loewy

Chang-Lit

, et al. Effects of live music on the perception of noise in the SICU/PICU: a patient, caregiver, and medical staff environmental study. Int J Environ Res Public Health 2023; 20: 3499.

30.

Fausti

Santoni

Secchi

Noise control in hospitals: considerations on regulations, design and real situations. In: INTER-NOISE and NOISE-CON congress and conference proceedings, Madrid, 2019, pp.7952-7962. Institute of Noise Control Engineering.

31.

Rasmussen

Carrascal

Secchi

A comparative study of acoustic regulations for hospital bedrooms in selected countries in Europe. Buildings 2023; 13: 578.

32.

Zhou

Meng

, et al. Influence of the acoustic environment in hospital wards on patient physiological and psychological indices. Front Psychol 2020; 11: 549334.

33.

Berglund

Lindvall

Schwela

, et al. Guidelines for community noise. World Health Organization, Geneva, 1999.

34.

Drass

Kraus

Riedel

, et al. Soundlab AI-machine learning for sound insulation value predictions of various glass assemblies. Glass Struct Eng 2022; 7: 101–118.

35.

Andrade

de Lima

Martins

ACG

, et al. Urban noise assessment in hospitals: measurements and mapping in the context of the city of Sorocaba, Brazil. Environ Monit Assess 2024; 196: 267.

36.

Montes-González

Barrigón-Morillas

Gómez Escobar

, et al. Environmental noise around hospital areas: a case study. Environments 2019; 6: 41.

37.

Torresin

Aletta

Babich

, et al. Acoustics for supportive and healthy buildings: emerging themes on indoor soundscape research. Sustainability 2020; 12: 6054.

38.

Sejdinović

Modern thermal insulation and sound insulation materials. In: Advanced Technologies, Systems, and Applications VII (pp.218-233), 2022, pp.218-233. Springer.

39.

Moretti

Belloni

Agosti

Innovative mineral fiber insulation panels for buildings: thermal and acoustic characterization. Appl Energy 2016; 169: 421–432.

40.

Yan

Meng

Luo

, et al. Experimental study on improving the properties of rock wool and glass wool by silica aerogel. Energy Build 2021; 247: 111146.

41.

Tolba

El Mokadem

Badawy

, et al. A retrofitting framework for improving curtain wall performance by the integration of adaptive technologies. J Build Eng 2023; 80: 107979.

42.

Lee

Jung

Tuning sound absorbing properties of open cell polyurethane foam by impregnating graphene oxide. Appl Acoust 2019; 151: 10–21.

43.

Aly

Seddeq

Elnagar

, et al. Acoustic and thermal performance of sustainable fiber reinforced thermoplastic composite panels for insulation in buildings. J Build Eng 2021; 40: 102747.

44.

Kumar

Lee

HP.

The present and future role of acoustic metamaterials for architectural and urban noise mitigations. In: Acoustics, 2019, pp.590-607. MDPI.

45.

Darbyshire

Young

JD.

An investigation of sound levels on intensive care units with reference to the WHO guidelines. Crit Care 2013; 17: 1–8.

46.

Palestine

Instructions for licensing Palestinian hospitals. http://muqtafi.birzeit.edu/pg/getleg.asp?id=17380 (2020).

47.

RAPE ONE. Room acoustics design & noise source simulation software. https://www.softdb.com/products/rapone2/ (second edition).

48.

Veyseh

Mirmohamadi

Hakaki

, et al. Assessment of parameters affecting compressive behavior of mineral wool insulations. 2007.

49.

Miller

NP.

Transportation noise and recreational lands. Noise News International 2003; 11: 9–21.

50.

Selim

Saeed

Soliman

, et al. Achieving acoustic comfort in medical health care units: Dr. Plaza capital medical health care unit. A case study. Rom J Acoust Vib 2024; 21: 43–52.