Elevator Selection Methodology for Existing Residential Buildings Oriented Toward Living Quality Improvement

Abstract

With the intensification of aging populations and economic development, installing elevators in existing residential buildings has become crucial for achieving SDG 11 (Sustainable Cities and Communities). While elevator retrofits improve accessibility, they may also compromise living quality through obstructed ventilation, reduced daylighting, visual interference, and noise pollution. Despite provincial guidelines in China specifying elevator types for retrofitting, the lack of clear selection criteria complicates implementation. This study addresses the challenge of scientifically selecting elevator types that balance accessibility improvements with minimal impact on residential environments. Focusing on 50 operational elevator retrofits in eight Beijing communities employing eight half-landing elevator models from the Beijing Multi-story Residential Elevator Retrofit Guidelines, we establish a comprehensive evaluation framework integrating objective measurements (indoor ventilation, noise, daylighting, and external visibility) and subjective resident assessments. Taking Xicheng District’s Yutaoyuan Community as a case study, this research identifies the optimal elevator configuration through a multi-criteria analysis. The proposed methodology offers two key contributions: (1) a practical elevator selection system providing technical and theoretical support for nationwide retrofitting projects, and (2) a quantifiable assessment tool aligning with the 2030 Sustainable Development Agenda for urban renewal objectives.

1. Introduction

According to projections from China’s National Bureau of Statistics, the proportion of the population aged 60 and above in mainland China will reach approximately 25% by 2030, marking the nation’s transition from a “mildly aging” to a “moderately aging” society during the 14th Five-Year Plan period [1,2,3]. Home-based elderly care, as a critical strategy for addressing population aging and a key component of China’s elderly service system, remains and will continue to be the dominant form of elderly care [4,5]. Retrofitting elevators in existing multi-story residential buildings is both an essential measure for facilitating aging in place and a significant public concern prioritized by governments at all levels [6,7]. As of August 2024, 26 provinces, autonomous regions, and municipalities in China have issued official documents such as “Technical Guidelines for Elevator Retrofitting in Existing Multi-Story Residential Buildings” [8,9].

Field investigations across over 30 communities in Beijing’s Dongcheng, Xicheng, and Haidian districts either retrofitted with elevators or that are planning retrofits revealed multiple elevator model options available for identical building types. Taking Xicheng District as an example, the “Beijing Technical Guidelines for Elevator Retrofitting” (hereafter “Guidelines”) [8] issued in 2020 specify 13 commonly used elevator models (abbreviated as “Elevator n”). The elevator configurations were categorized into two types based on stopping positions: semi-level stop and level-level stop. Furthermore, the semi-level stop elevators were subdivided into eight types (Figure 1), while the level-level stop elevators were classified into five types, with classifications determined by factors including elevator shaft location, connecting corridor length, entrance door and accessible ramp positions, as well as window dimensions and placement. However, no standardized criteria exist for selecting optimal elevator types based on specific building characteristics. This ambiguity has led to issues such as excessive costs, spatial inefficiency, and reduced living quality when inappropriate models are chosen, subsequently dampening community enthusiasm for retrofits and slowing overall progress.

As a critical issue concerning people’s livelihood, domestic theoretical research on elevator retrofitting primarily focuses on installation procedures, negotiation methods, and optimization of supportive policies [10,11,12]. Practical studies in China mainly concentrate on summarizing the common patterns of residential elevator additions, proposing design rules for overall planning, architectural design, structural design, and electromechanical equipment [13,14,15]. Developed countries such as those in Europe and America have earlier adopted systematic evaluation methods in existing building retrofits. For instance, some U.S. states enforce elevator installations in multi-story residential buildings through the “Accessibility Design Standards” (ADA) and optimize solutions based on user satisfaction surveys (e.g., noise and privacy perception) [16]. Germany employs energy consumption simulations and life cycle cost analysis (LCCA) to select elevator models yet often overlooks residential quality and comfort indicators [17]. Japan introduced the “Universal Design” concept in aging community renovations, emphasizing the seamless integration of elevators with building forms, but its evaluation system prioritizes technical compliance over residents’ subjective experiences [18]. In summary, current research both domestically and internationally often segregates objective and subjective indicators, lacking a comprehensive evaluation framework that precisely aligns with residents’ living quality and in-depth qualitative and quantitative analyses of retrofitting details. This reliance on subjective preferences alone fails to comprehensively and effectively address public concerns. Therefore, it is essential to focus on currently implemented residential elevator retrofitting projects, integrating the scientific analysis of objective data with subjective questionnaires, to develop a more objective and multidimensional comprehensive selection method for existing residential elevator retrofits.

2. Comprehensive Methodology for Elevator Configuration Selection in Existing Multi-Story Residential Buildings

2.1. Experimental, Investigated, and Survey Subjects

The experimental subject refers to a building scheduled for elevator retrofitting where the proposed comprehensive elevator selection methodology (hereafter “the Methodology”) prioritizing living quality in existing residential buildings is ultimately applied and validated. Surveyed subjects are retrofitted buildings selected based on their alignment with the experimental subject’s architectural features and compatible elevator types. These buildings undergo field measurements and simulations for indoor ventilation, noise, lighting, and visual access. Discrepancies between measured and simulated data inform parameter adjustments to ensure simulation accuracy for subsequent experimental analyses. Respondents are residents of both experimental and surveyed buildings, providing critical data through questionnaires and interviews.

Experimental subject: The experimental subject was Yutao Garden Community in Xicheng District, Beijing, located in Xinjiekou Subdistrict, where 70% of residents are aged 65 or older. During the “Evaluation of Elevator Retrofitting in Multi-Story Residential Buildings in Xinjiekou, Xicheng District”, surveys revealed that 52% of residents experience difficulties with stair access, 27% limit their mobility due to physical constraints, and 11% are entirely homebound, underscoring strong community demand for elevator retrofits [19,20].

The community features three-units-per-floor layouts, with each unit comprising two bedrooms and one living room. The total floor area per level is 212 m² (185 m² net area + 27 m² shared space). Following the “Guidelines”, eight half-floor landing elevator models are compatible with this building type. The Methodology evaluates these models to identify the optimal choice for preserving living quality.

Surveyed subject: Surveyed buildings were selected based on architectural congruence with the experimental subject:

(1) Flat building facades with exterior walls aligned uniformly;

(2) Slab-style residential buildings measuring 18 m (width) × 12 m (depth), with rooms adjacent to the retrofit façade having a 4 m depth (length-to-width ratio: 1.45);

(3) Central stairwells with landing platforms flush with room boundaries, featuring symmetrical layouts along the stairwell’s longitudinal axis;

(4) Six exterior-facing rooms per floor with operable windows, yielding a 16.3% window-to-wall ratio on the retrofit façade.

Eight communities meeting these criteria were selected (Figure 2): Xihuangchenggen South Street No. 45, Xihuangchenggen South Street Zone 1, Chegongzhuangzhongli, Xiaomachangnanli, Huaibaishu North Street, Ministry of Materials Compound, Honglianzhongli, and Hongju South Street No. 1. Each community implemented one of the eight half-floor landing elevator models specified in the “Guidelines”. Parameter calibration was conducted by comparing field measurements with simulations, ensuring errors remained below 10% to guarantee simulation reliability [21,22].

The half-floor stop elevator retrofitting method involves positioning the elevator lobby at the staircase landing, requiring residents to ascend or descend half a flight of stairs to reach their target floor. This approach is suitable for space-constrained older residential buildings, offering lower installation costs but not achieving full accessibility. In contrast, the level-stop method directly connects the elevator lobby to residents’ balconies or rooms, providing full accessibility but requiring more installation space and potentially affecting natural lighting and ventilation [23,24]. Considering the limited land availability and complex utility networks in the experimental site, Yutao Yuan Community, the half-floor stop method was adopted to minimize impacts on the existing environment. Therefore, this study focused on identifying the optimal elevator type under the half-floor stop approach, with the research subjects being 50 residential units that already implemented this retrofitting method [25].

The study’s respondents comprised 48 residents from 10 buildings scheduled for elevator retrofitting and 196 residents from 40 buildings where elevator retrofitting was already completed, totaling 244 participants. A stratified sampling method was employed, with stratification based on gender, floor distribution, and elevator type. The sample consisted of 54.78% males and 45.22% females, approximating a 1:1 ratio. The distribution of respondents across floors was balanced, with a ratio of ground-floor residents, mid-floor residents, and top-floor residents of approximately 1:3:1. Within each elevator type group, secondary stratification by floor ensured balanced representation, capturing the opinions and experiences of residents across different elevator types and floor levels [26,27].

The questionnaire collected information on user demographics, residential quality satisfaction, elevator costs, and operational maintenance. Demographic data included property ownership, years since construction, design lifespan, gender, age, physical condition, occupation, floor level, the lead department for elevator installation, and information acquisition channels. Residential quality assessment focused on residents’ subjective evaluations of various environmental indicators. Cost analysis covered purchase and installation expenses, while operational aspects included maintenance and safety management.

Reliability was assessed using Cronbach’s α coefficient to evaluate internal consistency. A pre-test sample of 30 yielded an α of 0.873 for the residential quality perception dimension, exceeding the 0.7 threshold, indicating good reliability [28]. Validity testing encompassed content and construct validity. For content validity, three architecture professors and two sociology professors independently reviewed the questionnaire, resulting in the removal of three ambiguous items and adjustment of five scale items, retaining 20 core questions directly related to residential quality. The final content validity ratio (CVR) was ≥0.8, confirming content validity [29]. Construct validity was established through exploratory factor analysis (EFA), which validated the four-factor structure of the residential quality perception module (KMO = 0.787, Bartlett’s Test p < 0.001), with a cumulative variance explanation rate of 76.2% [30].

2.2. Factors Influencing Elevator Type Selection

To identify the optimal elevator type for specific building layouts, it is crucial to establish evaluation criteria for comparing different models [31,32]. The primary channels through which the public learns about elevator retrofitting in existing residential buildings and provides feedback include:

(1) Academic research and publications by scholars on influencing factors;

(2) Discussions on social media platforms regarding implementation progress, challenges, and trade-offs;

(3) Policy documents on government websites. This study integrates findings from the existing literature with crawled web data, filtering and ranking information based on discussion frequency and relevance to identify key factors affecting elevator selection.

The literature review revealed diverse perspectives on influencing factors: Li Wanrong and Song Kun [33] summarized functional, economic, and operational dimensions using a combination of quantitative and qualitative methods. Liu Yang and Liu Lin [34] explored the relationship between elevator retrofitting and living quality through six aspects: accessibility, ventilation, daylighting, visual access, site conditions, and universal design. Wang Jianjun and Xiong Zhenzhen [23] categorized influencing factors into four areas: building layout, indoor environmental quality, structural safety, and underground utilities. Chai Yiping [35] discussed challenges related to indoor environmental impacts, structural safety, and funding mechanisms.

In summary, research has gradually shifted focus from sociological stakeholder coordination [36,37,38] to technical considerations, emphasizing comprehensive evaluations of post-retrofit living quality, construction costs, and operational sustainability. Scholars universally recommend objective assessments to minimize adverse impacts on daylighting, ventilation, structural safety, fire safety, and aesthetics [39,40,41,42].

Based on the conclusions from the literature review, this study filtered and integrated web data. In September 2024, 982 trending topics and 14,232 comments under the keyword “elevator retrofitting in existing residential buildings” were collected from Google, Baidu, Xiaohongshu, Bilibili, and Weibo. After removing irrelevant information and merging semantically similar entries, factors influencing living quality post-retrofitting were identified from public concerns (Figure 3).

An analysis of the web data revealed 4077 valid entries, with public concerns primarily focused on three areas: living quality (2670 entries), construction costs (1125 entries), and operational maintenance (282 entries). Living quality-related topics accounted for over half of the discussions, highlighting it as the dominant public concern. Regarding construction costs, a comparison of post-subsidy installation prices from three contractors—Beijing Xingjia Construction Engineering Co., Ltd. (Beijing, China), Beijing Urban Construction Group Co., Ltd. (Beijing, China), and Beijing Fangdi Tianyu Special Equipment Installation Co., Ltd. (Beijing, China)—showed prices ranging from RMB 242,000 to RMB 274,000 per unit. This translated to a household contribution difference of RMB 1000–3400. Among 244 surveyed residents, 208 (85.2%) prioritized the impact of elevator retrofitting on indoor living quality over cost variations. Operational costs followed a standardized tiered pricing model: RMB 500 per household for three-story buildings, increasing by RMB 100 per additional floor. Given the overwhelming focus on living quality, this study adopted it as the primary criterion for elevator selection.

2.3. Evaluation Process of the Comprehensive Selection Methodology

Based on the literature review and crawled web data, this study established an evaluation framework comprising four factors: indoor ventilation, indoor noise, indoor daylighting, and external visual access (Figure 4). The specific evaluation process was as follows:

(1) Determining the weight of each factor: This study employed the Analytic Hierarchy Process (AHP) to ascertain the weight of each evaluation factor within the comprehensive assessment framework.

The first step involved constructing a hierarchical structure model, where post-retrofitting indoor residential quality is designated as the goal layer (A) and indoor ventilation (B1), indoor noise (B2), indoor daylighting (B3), and outdoor view (B4) are established as the criterion layer.

The second step entailed designing a judgment matrix questionnaire based on the 1–9 scale method, which was distributed to 244 respondents who were required to pairwise compare the importance of the four criterion layer factors.

The third step involved constructing a comprehensive judgment matrix by aggregating all valid questionnaire data using the geometric mean method, forming a judgment matrix from the criterion layer to the goal layer to ensure the statistical significance of group decision-making.

The fourth step calculated the weights and conducted consistency checks, using the square root method to compute the eigenvector, obtain initial weight values, and perform consistency tests to ensure the credibility of the weight distribution [43].

(2) Parameter adjustment based on software simulations for surveyed subjects: This step ensured the accuracy of subsequent simulation analyses for the experimental subject. The surveyed subjects were first grouped by their installed elevator types, resulting in eight groups of five subjects each, with identical elevator types within each group. Simulations and field measurements were conducted for each group, and discrepancies between simulated and measured data were analyzed. Simulation parameters were adjusted until the error between simulated and measured data fell within 10% of the measured data, concluding the adjustment process [21,44].

(3) Application analysis based on the experimental subject: After obtaining simulation parameters for indoor wind, sound, light, and visual environments in the second step, these settings were applied to simulate the experimental subject. The analysis results were then converted into quantifiable evaluation values using relevant standards. The detailed quantification process is described in Section 4 of this paper.

(4) Determine the optimal elevator type and summarize findings: After quantifying the analysis results for indoor wind, sound, light, and visual environments, weighted scores were calculated for each elevator type based on the weights determined in the first step. The elevator types were then ranked according to their scores to identify the optimal type for the experimental subject. Finally, the comprehensive evaluation process was summarized by analyzing building typology, standard floor layouts, unit characteristics of the surveyed and experimental subjects, as well as the plan and structural features of different elevator types.

3. Weights of Factors in the Comprehensive Selection Methodology

As described in Section 2.3, the weights of factors influencing elevator retrofitting were determined through the Analytic Hierarchy Process (AHP) based on feedback from 244 residents (Figure 5). The prioritized weights of factors, as identified by residents, were as follows: indoor noise (42.192%) > indoor ventilation (34.01%) > indoor daylighting (18.952%) > external visual access (4.846%) (Figure 6). The AHP calculations yielded a maximum eigenvalue of 8.98, a consistency index (CI) of 0.122, and a corresponding random index (RI) of 1.404 from the RI table. Consequently, the consistency ratio (CR) was calculated as CR = CI/RI = 0.087, which is less than 0.1, indicating high reliability of the AHP results (

Table 1. AHP hierarchy analysis results of factors influencing elevator retrofitting.

Influencing Factors	Eigenvector	Weight (%)	Maximum Eigenvalue	CI Value
Indoor Ventilation	1.36	34.01	8.98	0.14
Indoor Noise	1.688	42.192
Indoor Daylighting	0.758	18.952
External Visual Access	0.194	4.846

) [45,46].

4. Evaluation Criteria in the Comprehensive Selection Methodology

4.1. Evaluation Results of Indoor Ventilation

First, field measurements were conducted on the surveyed objects. The indoor air velocity was measured using a DELIXI-1603A anemometer (Manufacturer: Delixi Electric, City: Yueqing, Country: China). The measurement points were arranged in a grid pattern. Since the dimensions of all rooms in the selected surveyed objects were less than 10 m, they were classified as small rooms. The spacing between measurement points was set to no more than one-fourth to one-third of the shorter side length of the room to capture the variation in air velocity within the room. Therefore, the spacing was set to one-third of the shorter side length of each room. The measurement height was 1.5 m, corresponding to the human breathing zone height [47,48,49]. The measurements were taken daily from 14:00 to 17:00 between 10 October and 20 October 2024. During the measurement process, certain errors may have arisen due to the precision limitations of the handheld anemometer (DELIXI-1603A with a nominal error of ±3%) and constraints in the measurement point arrangement (e.g., omission of localized airflow variations in corners, door gaps, and window crevices). However, by increasing the number of measurements at each point and controlling the deviation between measurements, the results can effectively reflect the actual indoor ventilation performance [50]. Each measurement point was recorded three times. If the difference between the maximum and minimum values at a single point exceeded 10% of the minimum value, additional measurements were taken; otherwise, the measurement was concluded [21,44].

Indoor wind environment simulations were conducted using the eddy3d v0.4.1.2 within Grasshopper, which is based on the steady-state RANS (Reynolds-Averaged Navier–Stokes) model. Compared to other CFD software, eddy3d excels in predicting steady-state building airflow and indoor ventilation with higher computational efficiency and accuracy [51]. The simulation utilized meteorological data for Beijing in 2023 from the Energy Plus website (epw format). Variations in epw data across different years and the simplified treatment of complex wall flow in eddy3d’s turbulence model may have led to the underestimation of local vortex intensity [52]. Therefore, this study adjusted the default software settings through grouped parameter tuning and sensitivity analysis based on measured data. By testing grid resolutions (0.3 m, 0.5 m, 0.8 m) and iteration counts (500, 1000, 1500), it was found that errors increased by over 5% when grid resolution exceeded 0.5 m, and wind speed fluctuations were less than 1% after 1000 iterations. Comparing simulation results with measured data and balancing accuracy and computational speed, the parameters were set as follows: wind tunnel dimensions of 100 m × 100 m × 80 m, background grid resolution of 0.5 m × 0.5 m, building grid refinement level of 3, iteration count of 1000, and wind speed measurement plane at 1.5 m above the indoor floor level. Under these settings, the maximum simulation error was 0.02 m/s for E3-3F, which was less than 10% of the measured value (Figure 7), indicating high reliability of the simulation data [53,54,55].

After obtaining the simulation parameters, the experimental subject was analyzed (Figure 8) and the results were scored using the PMV (predicted mean vote) method according to the ASHRAE 55–2017 standard [56] (Figure 9). The calculation method is shown in Equation (1), where the indoor wind comfort rating (dimensionless) ranges from 0 to 100, with higher values indicating better indoor wind comfort; v represents the indoor wind speed (m/s) and k is the steepness coefficient of the Gaussian correction term (dimensionless), controlling the decay rate of ratings in high wind speed areas (based on an air temperature of 22 °C, relative humidity of 50%, metabolic rate of 70 W/m², and clothing insulation of 1.0 clo; k = 5 was derived from the ASHRAE 55–2017 standard table.

$${Cr}_w=100·{\left({\displaystyle \frac{v}{0.3}}\right)}^2·\left(2-{\displaystyle \frac{v}{0.3}}\right)·e^{-k·{\left({\displaystyle \frac{v-0.3}{0.3}}\right)}^2}$$

(1)

The final indoor ventilation evaluation scores were as follows: Elevator Type 2 (86.427) > Elevator Type 4 (85.089) > Elevator Type 5 (76.659) > Elevator Type 7 (71.682) > Elevator Type 8 (68.458) > Elevator Type 1 (52.120) > Elevator Type 6 (50.377) > Elevator Type 3 (43.577) (

Table 2. Measured and simulated indoor ventilation evaluations for experimental and surveyed buildings.

Research Object\Influencing Factors		Measured Average Wind Speed at Each Floor (m/s)			Simulated Average Wind Speed at Each Floor (m/s)			Overall Score
		Ground Floor (1F)	Middle Floor (3F)	Top Floor (6F)	Ground Floor (1F)	Middle Floor (3F)	Top Floor (6F)
Research Object	No. 45 Courtyard, South Xihuangchenggen Street (E1)	0.187	0.155	0.214	0.195	0.165	0.211	\
	District 1, South Xihuangchenggen Street (E2)	0.253	0.223	0.24	0.269	0.231	0.259	\
	Chegongzhuang Zhongli Community (E3)	0.2	0.237	0.181	0.209	0.217	0.185	\
	Xiaomachang Nanli Community (E4)	0.251	0.245	0.225	0.237	0.265	0.246	\
	Huaibaishu Street Beili Community (E5)	0.246	0.251	0.284	0.265	0.232	0.275	\
	Wuzi Department Courtyard (E6)	0.193	0.180	0.226	0.212	0.174	0.231	\
	Honglian Zhongli Community (E7)	0.176	0.227	0.223	0.185	0.220	0.228	\
	No. 1 Courtyard, Hongju South Street (E8)	0.28	0.195	0.221	0.297	0.209	0.216	\
Experimental Object	Yutao Yuan Community (Current situation)	0.187	0.155	0.214	0.195	0.165	0.211	\
	Yutao Yuan Community (E1)	\	\	\	0.174	0.189	0.235	52.120
	Yutao Yuan Community (E2)	\	\	\	0.227	0.269	0.268	86.427
	Yutao Yuan Community (E3)	\	\	\	0.142	0.192	0.224	43.577
	Yutao Yuan Community (E4)	\	\	\	0.217	0.254	0.285	85.089
	Yutao Yuan Community (E5)	\	\	\	0.195	0.229	0.287	75.659
	Yutao Yuan Community (E6)	\	\	\	0.160	0.216	0.214	50.377
	Yutao Yuan Community (E7)	\	\	\	0.192	0.239	0.277	76.051
	Yutao Yuan Community (E8)	\	\	\	0.177	0.244	0.251	68.458

As described in Section 2.3 the role of the survey subjects was to calibrate the software by comparing their measured and simulated values. Therefore, Table 2 only records the measured and simulated values of the survey subjects, without including final scores. As outlined in Section 2.3, the accuracy of the simulated data for the experimental subjects was ensured after software calibration. Since the experimental subjects were in a pre-retrofitting state without actual elevator installations, only simulation analysis was conducted for these subjects and no further measured analysis was performed.

).

4.2. Evaluation Results of Indoor Noise

First, a measured analysis was conducted for each survey subject using the SMART SENSOR-AM824 sound level meter (Manufacturer: Smart Sensor, City: Dongguan, Country: China) to measure indoor sound pressure levels. The arrangement of measurement points for indoor acoustic environments and the methods for data validity verification were consistent with those for indoor wind environments [57,58]. Multiple measurements were taken to reduce errors caused by the sound level meter’s precision limitations (SMART SENSOR-AM824 with a nominal error of ±1.5 dB) and incomplete isolation of background noise. This was achieved by controlling the deviation between maximum and minimum values and calculating the mean. For indoor acoustic environment simulations, Pachyderm Acoustic v2.6.0.5 was employed. This software includes a built-in elevator room frequency spectrum library and allows the customization of sound power level curves, offering advantages over generic acoustic software (e.g., Odeon) that uses simplified point source models. The primary noise sources in the simulation were the elevator room and elevator car noise sources provided by Pachyderm Acoustic. By comparing simulation results with measured data and balancing accuracy and computational speed, the final simulation parameters were determined as follows: acoustic properties of building materials were set for typical multi-story residential buildings, the iteration count was set to 800, and the noise measurement plane was positioned 1.5 m above the indoor floor level [59,60,61,62]. Under these settings, the maximum error was 4.459 dB for E3-6F, which was less than 10% of the measured value (Figure 10), indicating high reliability of the simulation data [21,44].

After obtaining the simulation parameters, the experimental subjects were analyzed (Figure 11) and the results were scored using the weighted delta JND method in Pachyderm Acoustic [63,64] (Figure 12). The calculation method is shown in Equation (2), where the indoor acoustic comfort rating (dimensionless) ranges from 0 to 100, with higher values indicating less noise impact on residential quality and greater comfort; L represents the noise sound pressure level (dB) and k is the decay exponent (dimensionless), determined as k = 1.43 based on the delta JND method and the room dimensions (all sides less than 10 m, classified as a small room).

$${Cr}_A=100·\left(1-{\left({\displaystyle \frac{L}{70}}\right)}^k\right)$$

(2)

The final indoor noise evaluation scores were as follows: Elevator Type 6 (90.091) > Elevator Type 2 (86.338) > Elevator Type 1 (80.717) > Elevator Type 3 (78.292) > Elevator Type 7 (72.241) > Elevator Type 8 (70.426) > Elevator Type 4 (69.325) > Elevator Type 5 (68.667) (

Table 3. Measured and simulated indoor noise evaluations for experimental and surveyed buildings.

Research Object\Influencing Factors		Measured Average Sound Pressure Level for Each Floor (dB)			Simulated Average Sound Pressure Level for Each Floor (dB)			Overall Score
		Ground Floor (1F)	Middle Floor (3F)	Top Floor (6F)	Ground Floor (1F)	Middle Floor (3F)	Top Floor (6F)
Research Object	No. 45 Courtyard, South Xihuangchenggen Street (E1)	39.378	45.828	46.500	38.674	42.9088	43.379	\
	District 1, South Xihuangchenggen Street (E2)	23.472	27.641	33.012	22.118	27.510	32.204	\
	Chegongzhuang Zhongli Community (E3)	43.436	48.276	49.056	40.9704	45.448	53.515	\
	Xiaomachang Nanli Community (E4)	47.371	62.036	63.376	43.435	60.150	62.118	\
	Huaibaishu Street Beili Community (E5)	48.276	53.804	55.560	45.789	51.017	54.579	\
	Wuzi Department Courtyard (E6)	29.798	36.644	37.811	26.766	39.267	41.721	\
	Honglian Zhongli Community (E7)	43.302	53.803	55.427	44.974	51.177	57.351	\
	No. 1 Courtyard, Hongju South Street (E8)	43.300	48.987	54.315	39.031	48.670	51.382	\
Experimental Object	Yutao Yuan Community (E1)	\	\	\	31.887	45.961	48.238	73.486
	Yutao Yuan Community (E2)	\	\	\	29.966	43.571	49.967	74.714
	Yutao Yuan Community (E3)	\	\	\	32.478	44.787	52.211	71.813
	Yutao Yuan Community (E4)	\	\	\	29.876	51.504	56.160	67.552
	Yutao Yuan Community (E5)	\	\	\	36.625	56.526	60.364	57.803
	Yutao Yuan Community (E6)	\	\	\	31.876	37.379	40.715	80.552
	Yutao Yuan Community (E7)	\	\	\	34.079	48.944	52.627	68.588
	Yutao Yuan Community (E8)	\	\	\	24.126	55.556	57.164	67.935

The recording considerations for Table 3 follow the same protocol as Table 2.

).

4.3. Evaluation Results of Indoor Daylighting

Indoor daylighting measurements were conducted using the SMART SENSOR-AS823 illuminance meter (Manufacturer: Smart Sensor, City: Shenzhen, Country: China) to measure indoor illuminance levels. The arrangement of measurement points for indoor daylighting, data validity verification, and methods were consistent with those for indoor ventilation. For indoor daylighting simulations, the Daylight Simulation plugin in Ladybug was employed, utilizing meteorological data for Beijing in 2023 from the Energy Plus website (epw format). Multiple measurements were taken to reduce errors caused by the illuminance meter’s precision limitations (SMART SENSOR-AS823 with a nominal error of ±5%) by controlling the deviation between maximum and minimum values and calculating the mean. By comparing simulation results with measured data and balancing accuracy and computational speed, the final simulation parameters were determined as follows: the acoustic properties of building materials were set for typical multi-story residential buildings, the building grid refinement level was set to 3, the iteration count was set to 700, and the daylighting measurement plane was positioned 1.5 m above the indoor floor level. Under these settings, the maximum error was 4.734% for E4-3F, which was less than 10% of the measured value (Figure 13), indicating high reliability of the simulation data [64,65,66].

After obtaining the simulation parameters, the experimental subjects were analyzed (Figure 14) and the results were scored according to the T/CECS 462-2017 “Evaluation Standard for Healthy Residential Buildings” [32] (Figure 15). The calculation method is shown in Equation (3), where E represents the Effective Daylight Area Ratio (dimensionless), ranging from 0 to 100, with higher values indicating a greater proportion of indoor area meeting effective daylighting criteria; the numerator is the area where the indoor daylight factor meets the standard, and the denominator is the total indoor area.

$$E=\left({\displaystyle \frac{A_c}{A_t}}\right)\times 100\%$$

(3)

The final indoor daylighting evaluation scores were as follows: Elevator Type 5 (92.760) > Elevator Type 3 (86.836) > Elevator Type 4 (80.643) > Elevator Type 6 (77.318) > Elevator Type 1 (76.823) > Elevator Type 8 (73.177) > Elevator Type 7 (72.890) > Elevator Type 2 (63.990) (

Table 4. Measured and simulated indoor daylighting evaluations for experimental and surveyed buildings.

Research Object\Influencing Factors		Proportion of Measured Indoor Effective Daylight Area (%)			Proportion of Simulated Indoor Effective Daylight Area (%)			Overall Score
		Ground Floor (1F)	Middle Floor (3F)	Top Floor (6F)	Ground Floor (1F)	Middle Floor (3F)	Top Floor (6F)
Research Object	No. 45 Courtyard, South Xihuangchenggen Street (E1)	42.346	51.906	56.689	44.668	49.721	55.496	\
	District 1, South Xihuangchenggen Street (E2)	44.987	38.941	42.459	42.159	37.710	40.866	\
	Chegongzhuang Zhongli Community (E3)	52.295	61.506	62.588	52.062	59.808	61.498	\
	Xiaomachang Nanli Community (E4)	51.898	59.082	66.377	53.042	54.348	67.578	\
	Huaibaishu Street Beili Community (E5)	60.298	63.614	72.117	58.776	65.060	68.664	\
	Wuzi Department Courtyard (E6)	44.646	53.052	57.846	47.350	50.077	57.098	\
	Honglian Zhongli Community (E7)	47.455	45.055	51.005	44.356	46.922	52.980	\
	No. 1 Courtyard, Hongju South Street (E8)	39.660	45.077	49.510	41.874	46.619	52.417	\
Experimental Object	Yutao Yuan Community (Current situation)	\	\	\	57.059	63.978	75.200	\
	Yutao Yuan Community (E1)	\	\	\	42.264	48.028	48.713	46.334
	Yutao Yuan Community (E2)	\	\	\	30.618	40.805	45.016	38.801
	Yutao Yuan Community (E3)	\	\	\	47.497	52.946	58.030	52.824
	Yutao Yuan Community (E4)	\	\	\	46.864	48.337	55.777	50.326
	Yutao Yuan Community (E5)	\	\	\	47.230	56.574	65.110	56.304
	Yutao Yuan Community (E6)	\	\	\	42.430	48.325	52.028	47.594
	Yutao Yuan Community (E7)	\	\	\	34.187	44.394	47.816	42.132
	Yutao Yuan Community (E8)	\	\	\	37.505	43.355	48.701	43.187

The recording considerations for Table 4 follow the same protocol as Table 2.

).

4.4. Evaluation Results of External Visual Access

For indoor visual aspects, the outdoor view ratio was adopted as the evaluation metric, defined as the proportion of outdoor landscape visible to occupants through windows or other openings in the building. Since the calculation results are solely influenced by the building and elevator layout, as well as the position and size of windows and doors, and do not involve fluid simulation, the software simulation results directly represented the actual measurements. Therefore, for indoor visual aspects, no comparison or feedback calibration between measured and simulated data was conducted based on survey subjects. Instead, the experimental subjects were directly used for parameter calibration. The View Analysis plugin in Ladybug was employed and, by comparing simulation results with measured data and balancing accuracy and computational speed, the final simulation parameters were determined as follows: view analysis precision was set to level 3, the iteration count was set to 50, and the outdoor view ratio analysis plane was positioned 1.5 m above the indoor floor level.

After obtaining the simulation parameters, the experimental subjects were analyzed (Figure 16), and the results were scored according to the LEED v4.1 “Green Building Rating System” [67,68,69] (Figure 17). The calculation method is shown in Equations (4) and (5), where x represents the outdoor view ratio; the numerator is the actual visible outdoor area; the denominator is the theoretical maximum visible area; the Indoor Outdoor View Evaluation Score (dimensionless) ranges from 0 to 100, with higher scores indicating greater occupant comfort regarding outdoor views; and k is the curve steepness coefficient, set to k = 2.5 based on the LEED v4.1 standard.

$$x=\left({\displaystyle \frac{A_v}{A_m}}\right)\times 100\%$$

(4)

$$E(x)=100·{\mathit{sin}}^2\left({\displaystyle \frac{\pi x}{70}}\right)·e^{-k·{\left({\displaystyle \frac{x-35}{35}}\right)}^2}$$

(5)

The final outdoor view evaluation scores were as follows: Elevator Type 5 (92.760) > Elevator Type 3 (86.836) > Elevator Type 4 (80.643) > Elevator Type 6 (77.318) > Elevator Type 1 (76.823) > Elevator Type 8 (73.177) > Elevator Type 7 (72.890) > Elevator Type 2 (63.990) (

Table 5. Simulated indoor visual access evaluations for experimental and surveyed buildings.

Research Object\Influencing Factors		Simulated Average Exterior View Ratio for Each Floor (%)			Overall Score
		Ground Floor (1F)	Middle Floor (3F)	Top Floor (6F)
Experimental Object	Yutao Yuan Community (Current situation)	\	29.166	\	\
	Yutao Yuan Community (E1)	\	20.040	\	35.129
	Yutao Yuan Community (E2)	\	35.316	\	98.338
	Yutao Yuan Community (E3)	\	27.006	\	73.252
	Yutao Yuan Community (E4)	\	15.866	\	18.273
	Yutao Yuan Community (E5)	\	37.620	\	95.384
	Yutao Yuan Community (E6)	\	24.663	\	60.123
	Yutao Yuan Community (E7)	\	19.972	\	34.801
	Yutao Yuan Community (E8)	\	30.768	\	90.531

Since outdoor visibility is solely affected by window position and size as well as outdoor obstructions, regardless of floor level, this table exclusively presents the outdoor visibility data for standard floors after installing each of the eight elevator types on the experimental subjects.

).

4.5. Optimal Elevator Selection for the Typical Building Type in Yutao Garden Community

Through a comprehensive evaluation of indoor ventilation, indoor noise, indoor daylighting, and external visual access, eight semi-level entrance elevators compatible with the standard building type in Yutao Garden Community, as listed in the “Atlas” issued by the Beijing Municipal Commission of Housing and Urban-Rural Development, were scored. The final scores were as follows: Elevator 2 (73.036) > Elevator 4 (67.863) > Elevator 5 (65.412) > Elevator 8 (64.517) > Elevator 7 (64.474) > Elevator 6 (63.053) > Elevator 1 (59.214) > Elevator 3 (58.680) (

Table 6. Living quality-oriented elevator evaluation matrix for retrofit candidates in Yutao Garden Community.

Elevator Model\Evaluation Factors	Indoor Ventilation (13.978%)	Indoor Noise (13.383%)	Indoor Daylighting (10.716%)	Exterior View (5.484%)	Overall Score
E1	52.120	73.486	46.334	35.129	59.214
E2	86.427	74.714	38.801	98.338	73.036
E3	43.577	71.813	52.824	73.252	58.680
E4	85.089	67.552	50.326	18.273	67.863
E5	75.659	57.803	56.304	95.384	65.412
E6	50.377	80.552	47.594	60.123	63.053
E7	76.051	68.588	42.132	34.801	64.474
E8	68.458	67.935	43.187	90.531	64.517

). Based on residential quality considerations, Elevator Model 2 was the most suitable option for the standard building type in Yutao Garden Community.

5. Conclusions

The field measurements and simulation results of the surveyed and experimental objects demonstrate that different types of elevator additions have significant impacts on the living quality of existing residential buildings. Although elevator installations inevitably affect the physical environment of residences, such as daylighting and ventilation, selecting an appropriate elevator type can effectively mitigate these impacts.

This study addresses the challenges and lack of scientific basis in selecting elevator types for existing residential buildings. Based on the proposed comprehensive selection methodology, the characteristics and extent of impacts of the eight elevator types listed in the “Atlas” on indoor living quality are summarized in terms of indoor ventilation, indoor noise, indoor daylighting, and external visual access.

(1) Indoor ventilation: The elevator shaft should ideally be positioned directly opposite the stairwell, with the elevator corridor length approximately 2.2 m, and the window area facing the prevailing summer wind direction should be maximized.

A comparison was made between the elevator types with the highest and lowest indoor ventilation scores. For E2, the elevator shaft was positioned directly opposite the staircase, with a connecting corridor length of 2.4 m, which is closer to the optimal corridor length (2.2 m) compared to other models. It featured windows on both sides with the largest window area, resulting in an average simulated wind speed of 0.255 m/s across all floors, demonstrating the best indoor ventilation performance. In contrast, E3 had an elevator shaft not positioned opposite the staircase, with windows oriented away from the prevailing summer wind direction and a smaller window area, yielding an average simulated wind speed of 0.186 m/s, indicating the poorest indoor ventilation performance. To minimize the impact of elevator installation on indoor ventilation, the following measures are recommended:

• The elevator shaft should ideally be positioned directly opposite the staircase: When the elevator shaft is aligned with the staircase, the impact on indoor ventilation is minimized, as seen in elevator models 2, 4, 5, and 8. Positioning the shaft on either side of the staircase significantly increases the impact, as observed in models 1, 3, 6, and 7.
• The length of the elevator-connecting corridor should be approximately 2.2 m: For example, in Beijing, where buildings are typically oriented north–south, a controlled variable analysis of the corridor length (ranging from 0 m to 3 m, with increments of 0.2 m, totaling 16 simulations) was conducted under the condition that the corridor faces the staircase without windows. The results showed that a corridor length of 2.2 m achieved the best ventilation, with an average indoor wind speed of 0.271 m/s. If the corridor is positioned on the sides of the building, a shorter corridor length reduces the impact on indoor ventilation.
• The elevator corridor should feature windows on both sides, preferably facing east: The corridor’s window configuration can be single-sided or double-sided, with a larger total window area favoring better indoor ventilation. For single-sided windows, a smaller angle between the window orientation and the prevailing summer wind direction of the building’s location enhances ventilation.

(2) Indoor noise: The elevator corridor should be detached from the building, and the distance between the elevator shaft and the building should be maximized.

A comparison was made between the elevator types with the highest and lowest indoor noise scores. For E6, the elevator shaft was detached from the building, and the elevator entrance door was not directly opposite the staircase. The connecting corridor length was 1.8 m, aligning with the noise-reducing layout described above. The average simulated sound pressure level across all floors was 36.663 dB, indicating the minimal impact of elevator noise on the residential interior. In contrast, E5 had an elevator shaft attached to the building, with the entrance door directly opposite the staircase and no connecting corridor. The average simulated sound pressure level across all floors was 51.172 dB, representing the greatest impact of elevator noise on the residential interior. To minimize the impact of elevator installation on indoor acoustic environments, the following measures are recommended:

• The elevator shaft should ideally be detached from the building: When the elevator shaft is attached to the building, the noise generated has the greatest impact on the interior. If the elevator shaft is detached and connected via a corridor, noise transmission into the interior is more likely when the corridor is perpendicular to the building. However, a corridor parallel to the building significantly reduces noise transmission.
• The length of the elevator-connecting corridor should preferably exceed 2 m: The greater the distance between the elevator shaft and the building, the smaller the impact of generated noise on the interior, with noise decreasing exponentially as the distance increases.

(3) Indoor daylighting: The elevator shaft should preferably be attached to the building, and the corridor should be constructed with glass curtain walls with high light transmittance. If the corridor is built with opaque materials, the window area should be maximized.

A comparison was made between the elevator types with the highest and lowest indoor daylighting scores. For E5, the elevator shaft was attached to the building, and no connecting corridor was installed. The average simulated value of effective daylighting areas across all floors was 56.305%, indicating the minimal impact of elevator installation on indoor daylighting. In contrast, for E2, the elevator shaft was detached from the building, and the connecting corridor was the longest among the eight models (2.4 m). The average simulated value of effective daylighting areas across all floors was 38.801%, representing the greatest impact of elevator installation on indoor daylighting. To minimize the impact of elevator installation on indoor daylighting, the following measures are recommended:

• The length of the elevator-connecting corridor should be as short as possible: longer corridors are less favorable for indoor daylighting.
• The corridor material should preferably be a glass curtain wall with an increased window area: If the corridor is constructed with opaque materials and partially windowed, a larger window area enhances indoor daylighting. If the corridor is made of transparent materials, higher light transmittance of the construction materials improves indoor daylighting.

(4) External visual access: Glass curtain walls with high light transmittance should be used, and the elevator shaft should preferably be attached to the building. If an elevator corridor is necessary, it should be connected perpendicularly to the building, and its length should be minimized. If obstacles such as drainage pipes or heating pipes in front of the building require the elevator shaft to be positioned on the left or right side of the corridor, the preferences of the building residents should be thoroughly considered. The elevator should be positioned near non-living spaces such as bathrooms or storage rooms, where external visual access is less critical, and affected residents should be provided with appropriate financial compensation.

A comparison was made between the elevator types with the highest and lowest outdoor view scores. For E2, the elevator shaft was detached from the building, and the connecting corridor was relatively long (2.4 m). However, it featured a double-sided window design, resulting in a simulated outdoor view ratio of 35.316% for the standard floor, achieving the highest outdoor view score after elevator installation. In contrast, for E4, the connecting corridor length was 1.5 m, and no windows were installed. The average simulated value of effective daylighting areas across all floors was 15.886%, representing the lowest outdoor view score after elevator installation. To minimize the impact of elevator installation on outdoor views, the following measures are recommended:

• High light transmittance materials for corridor and shaft: The higher the light transmittance of the materials used for the corridor and shaft is, the better the external visual access from the interior will be.
• Minimize corridor length and connect perpendicularly: If the elevator shaft is directly connected to the building, the impact on external visual access is minimized. If the shaft is connected via a corridor, a parallel arrangement significantly reduces external visual access for adjacent rooms, potentially blocking the view entirely. For example, in Elevator Model 1, where the shaft is positioned on the left side of the corridor, the external visual access for adjacent bathrooms and dining rooms is reduced to less than 10%. Therefore, a perpendicularly connected corridor provides better external visual access compared to a parallel arrangement.

(5) Summary: The proposed comprehensive selection methodology in this study provides a new approach to address the challenges and lack of scientific basis in selecting elevator types for existing residential buildings in old neighborhoods.

Nationwide, this method is also applicable to buildings with different layouts and unit types, as well as the various elevator types specified in the elevator installation standards of other provinces, demonstrating high scalability.

For the Beijing area, the surveyed and experimental objects in this study exhibit significant similarities in building type, standard floor plan, and unit characteristics. After applying the comprehensive selection methodology, the scores of each elevator type across the evaluation factors and the final total scores show a high degree of regularity. Based on the shared characteristics of the experimental and surveyed objects mentioned in Section 2.1, the following recommendations are proposed for buildings with these characteristics:

The comprehensive ranking of the eight semi-level stop elevator types in the “Atlas” (Elevator 2 > Elevator 4 > Elevator 5 > Elevator 8 > Elevator 7 > Elevator 6 > Elevator 1 > Elevator 3) derived in Section 4.5 provides direct and valuable reference for elevator selection in Beijing-area buildings that meet the characteristics described in Section 2.1.

From the perspective of living quality, considering indoor ventilation, noise, daylighting, and external visual access, the selected elevator type should have its shaft positioned directly opposite the stairwell, with the elevator entrance door facing the stairwell, and the corridor length should ideally be 1.8 m. If an L-shaped corridor is unavoidable due to objective constraints, the length of the corridor parallel to the building should be minimized. The corridor and shaft should be constructed with high light transmittance materials, and the corridor should have windows on both sides or a single side facing the prevailing summer wind direction (southeast in Beijing).

(6) Future research prospects: First, establish a collaborative evaluation system for multiple types of elevators. While this study focuses on semi-stop elevators, future work could incorporate level-stop and machine-room-less elevators to develop a comprehensive evaluation system across stopping modes. Additionally, the applicability of this method in different climate zones should be validated. Second, expand the current research scope across multiple dimensions. While the current evaluation framework emphasizes the physical environment, future studies could integrate structural safety (e.g., seismic adaptability in earthquake-prone areas), energy efficiency (e.g., carbon emissions from elevator operation), and economic costs (e.g., life cycle maintenance expenses) to form a multi-objective optimization model. Third, conduct long-term post-use evaluations of the experimental subjects. Selected experimental cases should be monitored for 5–10 years to analyze the cumulative effects of elevator aging on ventilation, noise, daylighting, and other factors.