Research on Design Strategy for Zero-Carbon Touristic Apartment Openings Based on Building Life Cycle

Abstract

The timeshare is gradually becoming an essential global tourism operation model, especially in rural areas of China, where the leisure industry is developing rapidly. Meanwhile, the environmental issues of the rapidly growing timeshare-related building production have received widespread attention. The existing research on zero-carbon buildings considers carbon emissions as a constant value and cannot adapt to the impact of user changes during the operation phase. Constructing a low-carbon design applicable to timeshare is significant for controlling carbon emissions in the construction industry and responding to the environmental crisis. The practical carbon emissions of touristic apartments depend on the requirement changes in different customer clusters. The timeshare theory reflects the requirement change in different customer clusters based on the timeshare property ownership change. This paper focuses on a dynamic design strategy for zero-carbon building openings to reduce practical carbon emissions. Firstly, this research clarifies the primary customer clusters and conducts a touristic apartment unit model by timeshare property ownership. Then, this research clarifies the changes in customer requirements to analyze the spatial function changes in the operating phase. Finally, the study identifies six dynamic carbon emission indicators, such as the window-to-wall ratio, ventilation rate, and effective daylight area, and through passive design methods, provides 13 variable devices applied in the operating phase to control dynamic carbon emission indicators by customers. This paper also offers a flexible method to effectively decrease and accurately control carbon emissions by reducing the possible device utility.

1. Introduction

The environmental crisis raises concerns in various industries worldwide [1]. Many countries have successively formulated national strategies to control carbon emissions. In September 2020, the Chinese government proposed two national strategic objectives of carbon emission control [2,3]. The construction and tourism industries are critical sources of CO₂ emissions, including 8–11% and 40% of the global carbon emissions [4]. To achieve the vital goal of carbon emission control, it is necessary to study the carbon emission laws of related industries and propose optimization design strategies [5]. Carbon emissions in the operating phase account for 80% of the building life cycle [6,7,8,9], the key phase to solving environmental problems and realizing the strategic objectives [10,11,12]. Consequently, the urgent problem is solving the primary carbon emissions of touristic building production in the operating phase of the building life cycle.

Previous research has grappled with identifying a building structure’s primary carbon emission sources for different types of buildings [13]. The building envelope is believed to be the most essential carbon emission source due to heat loss [14]. The openings of the building envelope critically and fundamentally impact the heating, cooling, and daylighting load, determining the utility and carbon emission of devices for heating, cooling, ventilation, and lighting [15]. Additionally, the window-to-wall ratio was the essential factor in carbon emissions by reducing cooling and heating carbon emissions with respect to visual and thermal comfort of the building interiors [16]. Some researchers insisted that the sizes and orientations of the windows also affected the building’s carbon emissions [17]. Other previous studies took the shape, position, and size of prefabricated buildings’ windows as variations, exploring the optimal window-to-wall ratio as a design strategy in the north of China [18]. However, the building productions’ ventilation, lighting or cooling, and heating features vary greatly depending on the users’ requirements [19]. There is a gap in past research regarding the discussion of the size, shape, orientation, position of windows, or analysis of the optimal window-to-wall ratio in a specific area, but the current research considered the users’ requirements for ventilation, lighting, heating, and so on in the building’s operating phase as constant numeration, which made it inaccurate to calculate and control the minimum of carbon emissions of the timeshare building. According to current research findings, carbon emissions depend on customers’ behaviors, especially in touristic buildings such as tourist apartments [20], and it is argued that reducing carbon emissions in the operating phase is effective by transforming the spatial functions based on the customers’ requirement changes [21,22,23]. Therefore, studying the carbon emission control design during the construction operation stage under different user demand orientations is significant, especially for the timeshare operation model [24,25]. Based on relevant timeshare research on customer requirement changes, this research aims to identify openings’ carbon emission indicators of the operating phase from a dynamic perspective to reduce carbon emissions by excessive device application. In addition, it also provides designers with a practical opening design strategy and a model for a typical touristic apartment for accurate carbon emission control.

2. Methodology

2.1. Timeshare Property Ownership

2.1.1. Timeshare Operation Model and Timeshare Primary Customer Cluster

Timeshare tourist buildings’ customers differ from other tourist buildings in their applications and concepts. Timeshare is a form of property ownership that allows the customer to occupy an accommodation or a facility for a defined period during a year over a specified number of years or perpetually, also known as intervals, fractional, or vacation ownership [26]. The first timeshare case was in the early 1960s [27]. Because joint ownership requires trust, and no property manager is involved, family groups are the majority of the customer groups [28,29]. The timeshare primary customers can be divided into four clusters: the family group, friends group, business group, and individual group [30]. Based on past research, the family group cluster has five sub-categories according to the Family Cycle theory [30,31]. Detailed timeshare primary customer cluster analysis is shown in

Table 1. Timeshare primary customer cluster.

Customer Cluster		Definition	Occupancy	Number of Bedrooms
Family Group	Beginning family	Newly married couples	2	1
	Expanding family	Couples with their first child	3	2
		Couples with more than one child	More than 3	2 or more
	Contracting family	A child left the family	2 or more	1, 2, or more
	Aged families	All the children left the family	2	1
Individual Group		Single customer	1	1
Business Group		Business Travelers	2 or more	1, 2, or more
Friends Group		Friends	2 or more	1, 2, or more

.

2.1.2. Touristic Apartment Unit Model of Timeshare Property Ownership

According to the customer cluster in Table 1, the touristic apartment model in this research takes a two-bedroom apartment as the minimal unit, including a kitchen, a bathroom, a living room, and two bedrooms, as shown in Figure 1. The two-bedroom unit can accommodate most family groups (one or two children), individual groups, business groups, or friend groups with four or fewer people. To provide a model for carbon emission calculation in the operating phase, this research takes the smallest room, the bathroom, to evaluate the customer requirement change impacts on openings (

Table 2. Touristic apartment unit model of timeshare property ownership.

NO.	Function	Area
①	Bedroom 1	6n
②	A living room	3n
③	A bathroom	n
④	A kitchen	2n
⑤	Bedroom 2	6n

Source: authors.

). The scale of the bathroom, n, is derived from the smallest unit that meets the human scale in the architectural design data set [32], and the plan organization is derived from the organized function based on the space of the touristic apartment in the spatial assemblage theory of architecture [33].

2.1.3. Theories of Developments of Consumer Value Changes in the Timeshare Industry

Customer requirements determine the value of productions because value exists only when the productions satisfy customers, which is believed to be the “relativistic preference” [34,35]. Some past leisure and touristic studies view the customers’ requirements as multi-dimensional and context-specific [36]. By analyzing the Japanese tourist industry, Lee et al. consider the requirements of three aspects [37]. Petric derived requirements into five dimensions: quality, emotional, monetary, behavioral, and reputation [38]. As a production with various interactions, timeshare is an appropriate research subject for customer requirement changes. This research applies Petric’s five dimensions to analyze touristic apartment unit requirements.

2.2. Research Framework

This research includes timeshare primary customer cluster identification and a touristic apartment unit model. Five-dimensional touristic customer requirement modes of quality, emotional, monetary, behavioral, and reputation were applied to classify spatial function changes in the primary customer clusters. Four primary timeshare customer clusters were identified. Flexible touristic apartment design for the four main customer segments can minimize carbon emissions during the operating phase. This study explores a touristic apartment unit model that maximally satisfies the requirements of four primary timeshare customer clusters through the passive design method. The touristic apartment unit model consists of six dynamic opening indicators in ventilation and lighting identified based on the customer clusters. The window-to-ground ratio, light correction coefficient, and effective daylight area, three dynamic carbon emission indicators, were used to clarify the ability of the design to meet the needs of different customer clusters during the operating phase. The window-to-wall ratio and ventilation quantity are secondary restricted indicators for further controlling carbon emissions based on meeting the needs of customer clusters. A total of 13 passive approaches were conducted to control the six indicators of openings, which can flexibly adjust ventilation and lighting in the operating phase. The research flow chart is shown in Figure 2.

3. Customer Requirement and Spatial Function Changes in the Operating Phase

3.1. Customer Requirement Changes in Primary Customer Clusters

Table 3. Main customer requirement changes in the operating phase.

Customer Cluster		Quality	Emotional	Monetary	Behavioral	Reputation
Family Group	Beginning family	Regular	Regular	More economical	More recreational space	Landscape visibility and entertainment
	Expanding family	High	Separate space for children	More economical	Child’s recreational space	Child-friendly and safety
				More economical	Larger child’s recreational space
	Contracting family	Regular	Regular	Cozier	No Special requirement	Landscape visibility
	Aged families	High	Separate space for caregiver	Cozier	Larger space to move	Age-friendly and safety
Individual Group		Regular	Regular	More economical	No Special requirement	Landscape visibility
Business Group		High	Regular	Cozier	More recreational space	Coziness
Friends Group		Regular	Separate space for Each person	More economical	Larger recreational space	Landscape visibility and entertainment

Source: authors.

analyzes the five dimensions of customer requirement changes in the operating phase. The quality requirements for each cluster were evaluated by the whole interior quality, including the requirement for lighting and temperature. Customers’ requirements on interior temperature and daylighting conditions are critical for the expanding family phase, aged families, and business groups. Emotional requirements were analyzed based on the customers’ independent requirements. Table 1 shows that the family and friends groups, except for the beginning family and contracting family phases, need more space for the group members. Because of financial restrictions, beginning families, expanding families, individual groups, and friend groups pay less attention to the quality of the facilities, such as room size. Behavioral requirements were analyzed based on the typical person’s activities. For instance, expanding families need more recreational space, while expanding families, business groups, and friends groups need more public spaces. The reputation requirements were analyzed using the most focused requirement for each cluster.

3.2. Correspondence Between Customer Requirement Changes and Spatial Function Changes

Based on the requirement analysis in Table 3,

Table 4. Main spatial function changes in the operating phase.

Customer Cluster		Functions
		Quality	Emotional	Monetary	Behavioral	Reputation
Family Group	Beginning family	——	——	Restricted	Entertainment room	Larger windows for landscape
	Family extension	Ventilation, daylighting	Children’s bedroom	Restricted	Entertainment room	No balcony
	Contracting family	——	——	——	——	Larger windows for landscape
	Aged families	Ventilation, daylighting	Caregiver room	——	Extra space to move	No balcony
Individual Group		——	——	Restricted	——	Larger windows for landscape
Business Group		Ventilation, daylighting	——	——	Entertainment room	Balcony
Friends Group		——	Friend’s room	Restricted	Entertainment room	Larger windows and entertainment room

Source: authors.

analyzes the practical spatial function changes in the primary customer clusters. The quality requirements were evaluated by interior quality, mainly ventilation and daylighting. As a restricted factor, monetary requirements determine other space function qualities, such as the functional space area and windows for viewing. The reputation requirements also serve as a restricted factor for reflecting the most focused requirement for each cluster. For the beginning family phase, contracting family phase, individual group, and friends group, larger windows for landscapes are the extra restricted factor. There is no balcony because of safety concerns for the expanding family and the aged family phases. The balcony and larger entertainment room are separately restricted factors for the business and friends groups.

Table 5. The spatial function changes in areas.

Customer Cluster		Layout	Spatial Function Changes	Area Changes	Extra Factors
					Additional Need for Light	Ventilation	Daylighting
Family Group	Beginning family		Bedroom 2 to Entertainment room	2n	NO	Normal	Normal
	Family extension		Bedroom 2 to Children’s bedroom	4n	YES	High	High
			Bedroom 2 to Entertainment room	2n	NO
	Contracting family		——	——	——	Normal	Normal
	Aged families		Bedroom 2 to Living room	6n	YES	High	High
			Bedroom 2 to Caregiver room	3n	NO
Individual Group			——	——	——	Normal	Norma
Business Group			Bedroom 2 to Entertainment room	4n	NO	High	High
			Bedroom 2 to Balcony	2n	YES
Friends Group			Bedroom 2 to Entertainment room	6n	NO	Normal	Normal

Source: authors.

shows the layouts, ventilation, and daylighting changes according to the spatial function changes. This section’s result is the basic touristic apartment model in the operating phase for five clusters. These models are used as the coupling mechanisms for the opening design.

4. Analysis of Opening Design for Zero-Carbon Touristic Apartment in Operating Phase

4.1. Opening Layout Changes Based on the Spatial Function Changes

The openings for each cluster based on spatial function changes in the operating phase are presented in

Table 6. The number and space area changes in openings based on spatial function changes in the operating phase.

Customer Cluster		No.	Name	Area	The Openings
All customer groups		①	Bedroom 1	No changes	Interior Door A
					Sliding Door A
				Increase	Window A
Family Group	Beginning family	②	Living room	No changes	Exterior Door A
	Family extension				Interior Door A
					Window E
	Contracting family				Interior Door B
	Aged families			Increase	Interior Door C
Individual Group				No changes	Sliding Door B
Business Group					Window B
Friends Group
All customer groups		③	Bathroom	No changes	Interior Door B
					Window C
					Sliding Door C
All customer groups		④	Kitchen	No changes	Sliding Door B
Family Group	Beginning family	⑤	Entertainment room	Decrease	Interior Door B
	Expanding family		Children’s bedroom
			Entertainment room
	Contracting family		——	——	Window D
	Aged families		Living room	Increase	Window E
			Caregiver room	Decrease
Individual Group			——	——	Sliding Door D
Business Group			Entertainment room	Decrease
			Balcony
Friends Group			Entertainment room	No Change

Source: authors.

. The openings, such as numeration and location, directly affect the ventilation, daylighting, and functional changes in the operating phase. Table 6 shows that the expanding family phase, the aged families phase, and the business group have additional openings for the lighting need, as shown in Table 5. The other groups have the exact opening location as the primitively touristic apartment unit model in Section 2.1.2. The opening layout changes for each cluster are illustrated in Figure 3. The scales of the openings are derived from industry standards [39,40,41].

4.2. Carbon Emission Indicator Control of the Touristic Apartment Opening Scales

Table 7. Zero-carbon touristic apartment opening scales control table.

Customer Cluster		NO.	Name	Space Aera	Openings	Scales	Aera	R				K			J
								Ventilation Quantity		Data	Standard Data	Data	Standard Data		Data	Enhancement Ratio
								Data	Standard Data
Family Group	Contracting family	⑤	Bedroom 2	6n	Interior Door B	900 × 2100 mm	1.89 m2	-	-	-	-	-	-	-	More than 2.09 m2
					Sliding Door D	1200 × 2100 mm	2.52 m2	6.05 m2	More than 0.731 m2	0.41	1/7	3.24D-1.4	More than 1.84	4.64		1.22
					Window D	2500 × 1500 mm	3.75 m2	9 m2	More than 0.731 m2	0.256	1/7	3.87D-1.4	More than 2.47	9.263 m2		3.43
	Beginning family	⑤	Entertainment room	2n	Window D	1500 × 2500 mm	3.75 m2	9 m2	More than 0.245 m2	0.765	1/7	2.93D-1.4	More than 1.53	5.74 m2	More than 0.7 m2	7.21
	Expanding family	⑤	Children’s bedroom	4n	Window D	2500 × 2000 mm	5 m2	12 m2	More than 0.50 m2	0.51	1/7	3.33D-1.4	More than 1.93	9.650 m2	More than 1.39 m2	5.94
			Entertainment room	2n	Window E	2500 × 1500 mm	3.15 m2	7.56 m2	More than 0.245 m2	0.64	1/7	3.87D-1.4	More than 2.47	7.781 m2	More than 0.7 m2	10.12
					Interior Door B	900 × 2100 mm	1.89 m2	4.5 m2	-	-	-	-	-	-	-
	Aged families	⑤	Living room	7n	Window B	3000 × 1500 mm	4.50 m2	10.8 m2	More than 0.733 m2	0.31	1/7	3.87D-1.4	More than 2.47	11.115 m2	More than 2.094 m2	4.31
					Exterior Door A	1200 × 2100 mm	2.52 m2	-		-		-	-	-	-	-
					Interior Door A	800 × 2100 mm	1.68 m2	-		-		-	-	-	-	-
					Interior Door C	900 × 2100 mm	1.89 m2	-		-		-	-	-	-	-
					Sliding Door B	1200 × 2100 mm	2.52 m2	6.0 m2		0.17		3.24D-1.4	More than 1.84	4.64 m2	More than 2.094 m2	1.06
			Caregiver room	3n	Window D	3000 × 1500 mm	4.50 m2	10.8 m2	More than 0.366 m2	0.62		3.87D-1.4	More than 2.47	11.115 m2	More than 1.044 m2	9.65
Business Group		⑤	Entertainment room	4n	Interior Door B	900 × 2100 mm	1.89 m2	4.5 m2	-	-	-	-	-	-	-	-
					Window E	2500 × 1500 mm	3.75 m2	9 m2	More than 0.49 m2	0.38	1/7	3.87D-1.4	More than 2.47	9.26 m2	More than 1.394 m2	5.64
			Balcony	2n	Sliding Door D	1200 × 2100 mm	2.52 m2	2.1 m2	More than 0.24 m2	0.51	1/7	3.24D-1.4	More than 1.84	4.64 m2	More than 0.7 m2	5.63
					Window D	2500 × 1500 mm	3.15 m2	9 m2		0.77	1/7	3.87D-1.4	More than 2.47	5.74 m2	More than 0.7 m2	7.2
Friends Group		⑤	Entertainment room	6n	Interior Door B	900 × 2100 mm	1.89 m2	4.5 m2	More than 0.731 m2	-	-	-	-	-	-	-
					Window D	2500 × 1500 mm	3.75 m2	9 m2		0.26	1/7	3.87D-1.4	More than 2.47	9.26 m2	More than 2.09 m2	3.43
Beginning family		②	Living room	3n	Exterior Door A	1200 × 2100 mm	2.52 m2	-	-	-	-	-	-	-		-
Expanding family					Interior Door A	800 × 2100 mm	1.68 m2	-	-	-	-	-	-	-		-
Contracting family					Interior Door B	900 × 2100 mm	1.89 m2	-	-	-	-	-	-	-		-
Individual Group					Interior Door C	900 × 2100 mm	1.89 m2	-	-	-	-	-	-	-		-
Business Group					Sliding Door B	1200 × 2100 mm	2.52 m2	6.048 m2	More than 0.367 m2	0.34	1/7	3.24D-1.4	More than 1.84	4.637 m2	More than 1.05 m2	3.42
Friends Group					Window B	1500 × 2100 mm	3.15 m2	7.56 m2		0.429	1/7	3.24D-1.4	More than 1.84	5.796 m2	More than 1.05 m2	4.52
Aged families		②	Living room	7n	Window B	3000 × 1500 mm	4.50 m2	10.8 m2	More than 0.733 m2	0.31	1/7	3.87D-1.4	More than 2.47	11.115 m2	More than 2.094 m2	4.31
					Exterior Door A	1200 × 2100 mm	2.52 m2	-		-	-	-	-	-	-	-
					Interior Door A	800 × 2100 mm	1.68 m2	-		-	-	-	-	-	-	-
					Interior Door C	900 × 2100 mm	1.89 m2	-		-	-	-	-	-	-	-
					Sliding Door B	1200 × 2100 mm	2.52 m2	6.0 m2		0.17	-	3.24D-1.4	More than 1.84	4.64 m2	More than 2.094 m2	1.22
All customer groups		③	Bathroom	n	Interior Door C	900 × 2100 mm	1.89 m2	-	More than 0.12 m2	-	-	-	-	-	-	-
					Sliding Door C	800 × 2100 mm	1.68 m2	4.032 m2		0.7	-	3.24 D-1.4	More than 1.84	3.09 m2	More than 0.12 m2	24.75
					Window C	600 × 1500 mm	0.9 m2	2.16 m2		0.375	1/7	3.87D-1.4	More than 2.47	2.223 m2		17.53
All customer groups		④	Kitchen	2n	Sliding Door B	1200 × 2100 mm	2.52 m2	2.52 m2	More than 0.49 m2	0.51	1/7	3.24D-1.4	More than 1.84	4.64 m2	More than 0.71 m2	5.54
All customer groups		①	Bedroom 1	6n	Interior Door A	800 × 2100 mm	1.68 m2	1.68 m2		-	-	-	-	-
					Sliding Door A	1200 × 2100 mm	2.52 m2	2.52 m2	More than 0.56 m2	0.17	1/7	3.24D-1.4	More than 1.84	4.64 m2	More than 2.09 m2	1.22
					Window A	2500 × 1500 mm	3.75 m2	3.75 m2		0.332	1/7	3.87D-1.4	More than 2.47	9.263 m2		3.43

Source: authors.

illustrates the carbon emission indicator control of the zero-carbon touristic apartment opening scales. The carbon emission indicators are based on ventilation and space illumination changes for the area changes in Table 5. To satisfy the ventilation and daylighting requirements in Section 3, the window-to-wall ratio, light correction coefficient, and effective daylight area are used to calculate ventilation and daylighting for each cluster. In addition, openings in the touristic apartment unit model use the JISA standard productions for calculations.

First, the window-to-ground ratio is applied to take the daylight and ventilation quality, shown in Table 6, as the standard and ensure the opening scales satisfy the ventilation and space illumination requirements. The calculation formula is as follows.

R = A ÷ S,

(1)

R: window-to-ground ratio. A: window opening (m²). S: space scale (m²).

Secondly, the light correction coefficient and effective daylight area are applied to rectify the opening scales. The light correction coefficient and effective daylight area can ensure that the daylighting, calculated by the window-to-ground ratio, satisfies the practical activities in the operating phase. The calculation formula is as follows.

K = 6 × D ÷ H − 1.4,

(2)

D: horizontal distance between the upper gable end of the window center and the adjacent building boundary. H: vertical distance from the center of the window to the lower edge of the cornice. K: light correction coefficient.

J = A1K1 + A2K2 + A3K3 + …+ AnKn,

(3)

J: effective daylight area.

Table 8. Zero-carbon touristic apartment opening scale amendment.

	Customer Cluster	No.	Name	The Openings	Scales	Area	Facade Area	G			V
								Data	Standard Data	Enhancement Ratio	Data	Standard Data	Enhancement Ratio
Family Group	Beginning family	⑤	Entertainment room	Window D	1500 × 2500 mm	3.75 m2	12.96 m2	0.29	Less than or equal to 0.45	0.36	3.75 m2	More than 0.245 m2	14.31
	Expanding family		Children’s bedroom	Window D	2500 × 2000 mm	5 m2	14.62 m2	0.34	Less than or equal to 0.45	0.24	5 m2	More than 0.50 m2	9
			Entertainment room	Window E	2500 × 1500 mm	3.15 m2	14.62 m2	0.22	Less than or equal to 0.40	0.45	3.15 m2	More than 0.245 m2	11.86
	Contracting family		Bedroom 2	Sliding Door D	1200 × 2100 mm	2.52 m2	14.62 m2	0.17	Less than or equal to 0.45	0.62	2.52 m2	More than 0.731 m2	2.45
				Window D	2500 × 1500 mm	3.75 m2	14.62 m2	0.26	Less than or equal to 0.45	0.42	3.75 m2	More than 0.731 m2	4.13
	Aged families		Living room	Window B	3000 × 1500 mm	4.50 m2	14.62 m2	0.31	Less than or equal to 0.45	0.31	4.50 m2	More than 0.367 m2	11.26
				Sliding Door B	1200 × 2100 mm	2.52 m2	14.62 m2	0.17	Less than or equal to 0.45	0.62	2.52 m2	More than 0.367 m2	5.87
			Caregiver room	Window D	3000 × 1500 mm	4.50 m2	14.62 m2	0.31	Less than or equal to 0.45	0.31	4.50 m2	More than 0.367 m2	11.26
Individual Group Aged families			Bedroom 2	Sliding Door D	1200 × 2100 mm	2.52 m2	14.62 m2	0.17	Less than or equal to 0.45	0.62	2.52 m2	More than 0.731 m2	2.45
				Window D	2500 × 1500 mm	3.75 m2	14.62 m2	0.26	Less than or equal to 0.45	0.42	3.75 m2	More than 0.731 m2	4.13
Business Group			Entertainment room	Window E	2500 × 1500 mm	3.75 m2	14.62 m2	0.26	Less than or equal to 0.4	0.35	3.75 m2	More than 0.49 m2	6.65
			Balcony	Sliding Door D	1200 × 2100 mm	2.52 m2	14.62 m2	0.17	Less than or equal to 0.45	0.62	2.52 m2	More than 0.49 m2	4.14
				Window D	2500 × 1500 mm	3.15 m2	14.62 m2	0.22	Less than or equal to 0.45	0.51	3.15 m2	More than 0.49 m2	5.43
Friends Group			Entertainment room	Window D	2500 × 1500 mm	3.15 m2	14.62 m2	0.22	Less than or equal to 0.45	0.51	3.15 m2	More than 0.731 m2	3.31
	Beginning family	②	Living room	Sliding Door B	1200 × 2100 mm	2.52 m2	14.70 m2	0.17	Less than or equal to 0.4	0.58	2.52 m2	More than 0.367 m2	5.87
	Expanding family			Window B	1500 × 2100 mm	3.15 m2	14.70 m2	0.21	Less than or equal to 0.4	0.48	3.15 m2	More than 0.367 m2	7.58
	Contracting family
	Individual Group
	Business Group
	Aged families		Living room	Window B	3000 × 1500 mm	4.50 m2	30.28 m2	0.15	Less than or equal to 0.45	0.67	4.50 m2	More than 0.733 m2	5.14
	All customer groups	③	Bathroom	Sliding Door C	800 × 2100 mm	1.68 m2	4.8 m2	0.35	Less than or equal to 0.45	0.22	1.68 m2	More than 0.12 m2	13
				Window C	600 × 1500 mm	0.9 m2	4.8 m2	0.19	Less than or equal to 0.45	0.58	0.9 m2	More than 0.12 m2	6.5
	All customer groups	④	Kitchen	Sliding Door B	1200 × 2100 mm	2.52 m2	9.9 m2	0.25	Less than or equal to 0.45	0.44	2.52 m2	More than 0.49 m2	4.14
	All customer groups	①	Bedroom 1	Sliding Door A	1200 × 2100 mm	2.52 m2	11.288 m2	0.22	Less than or equal to 0.45	0.51	2.52 m2	More than 0.56 m2	3.5
				Window A	2500 × 1500 mm	3.75 m2	11.288 m2	0.33	Less than or equal to 0.45	0.27	3.75 m2	More than 0.56 m2	5.70

Source: authors.

illustrates the opening scale amendment through the secondary restricted indicators, the ventilation quality, and the window-to-wall ratio. From Table 5, the opening area is the intermediate parameter to the amendment. Firstly, ventilation quality is used to examine the opening scale to determine whether it is proper to satisfy the customer’s requirements and prevent extra carbon emissions because of the excessive scales. Additionally, the window-to-wall ratio precisely controls the proper location and rate on the wall, so these two amendments can reduce the practical carbon emissions in the operating phase. This research defaults to flat roofs to avoid the impact on lighting and energy consumption due to changes in building shape.

Table 9. The touristic apartment unit model opening layout for four primary customer clusters.

Customer Cluster		Layout
Family Group	Beginning family
	Expanding family
	Contracting family
	Aged families
Individual Group
Business Group
Friends Group

Source: authors.

shows the touristic apartment unit model layout, opening location, and scales for each primary customer cluster. The two calculation formulas are as follows.

Q = C × A × V,

(4)

Q: ventilation quality. C: ventilation efficiency coefficient. A: window opening (m²). V: wind velocity.

G = A ÷ F,

(5)

G: window-to-wall ratio. F: building unit façade area.

The results shown in Table 9 are the detailed scales, locations, and numbers of the opening layouts for five clusters. The designed openings satisfy the practical ventilation and daylighting requirements in the operating phase. Carbon emission indicators minimize the use of light and ventilation.

5. The Opening Design Strategy

The critical passive design methods to reduce the practical carbon emissions are presented in

Table 10. Correspondence between passive design methods and mechanisms affecting carbon emission indicators.

Passive Design Methods	Passive Design Methods	Carbon Emission Indicators
		R	A	S	K	D	H	J	G	F	V
Eaves	Optimal method	—	—	—	↓	—	↓	↓	—	—	—
Low-E Glass		—	—	—	—	—	—	↑	—	—	—
Rotating hoods		—	—	—	—	—	—	—	—	—	↑
Wall Greening		↓	↓	—	—	—	—	↓	↓	—	—
Casement Window		↑	↑	—	—	—	—	↑	↑	—	↑
Painting with light-colored materials	Variable method	↑	—	—	—	—	—	↑	—	—	—
Adjustable sunshade components		↓	↓	—	—	—	—	↓	↓	—	—
Transparent or translucent sliding doors		↑	—	—	—	—	—	↑	—	—	—
Reflecting board		—	—	—	—	—	—	↑	—	—	—
Adjustable Reflectors		—	—	—	—	—	—	↑	—	—	—
Shutters		↑	↑		↑	—	—	↑	—	—	—
Adjustable shutter		↑	—	—	—	—	—	—	—	—	↑
Dimmable glass		—	↑	—	—	—	—	↑	—	—	—

Note: ↑ indicates an increase, and ↓ indicates a decrease. Source: authors.

and

Table 11. Energy design strategies for zero-energy house openings at various stages of FLC.

Customer Cluster		Spatial Function Changes	Extra Factors		Passive Design Methods	Carbon Emission Indicators
			Ventilation	Daylighting
Family Group	Beginning family	Bedroom 2 to Entertainment room	Normal	Normal	Eaves	K, H, J
					Low-E Glass	J
					Rotating hoods	V
					Wall Greening	R, A, J, G
					Casement Window	R, A, J, G, V
	Expanding family	Bedroom 2 to Children’s bedroom	High	High	Eaves	K, H, J
					Low-E Glass	J
					Rotating hoods	V
					Wall Greening	R, A, J, G
					Casement Window	R, A, J, G, V
		Bedroom 2 to Entertainment room			Painting with light-colored materials	R, J
					Transparent or translucent sliding doors	R, J
					Reflecting board	J
					Shutters	R, A, J, K
					Dimmable glass	A, J
	Contracting family	——	Normal	Normal	Eaves	K, H, J
					Low-E Glass	J
					Rotating hoods	V
					Wall Greening	R, A, J, G
					Casement Window	R, A, J, G, V
	Aged families	Bedroom 2 to Living room	High	High	Eaves	K, H, J
					Low-E Glass	J
					Rotating hoods	V
					Wall Greening	R, A, J, G
					Casement Window	R, A, J, G, V
		Bedroom 2 to Caregiver room			Adjustable sunshade components	R, A, J, G
					Transparent or translucent sliding doors	R, J
					Adjustable Reflectors	J
					Shutters	R, A, J, K
					Adjustable shutter	V
					Dimmable glass	A, J
Individual Group		——	Normal	Normal	Eaves	K, H, J
					Low-E Glass	J
					Rotating hoods	V
					Wall Greening	R, A, J, G
					Casement Window	R, A, J, G, V
Business Group		Bedroom 2 to Entertainment room	High	High	Eaves	K, H, J
					Low-E Glass	J
					Rotating hoods	V
					Wall Greening	R, A, J, G
					Casement Window	R, A, J, G, V
		Bedroom 2 to Balcony			Painting with light-colored materials	R, J
					Adjustable sunshade components	R, A, J, G
					Adjustable Reflectors	J
					Adjustable shutter	V
					Dimmable glass	A, J
Friends Group		Bedroom 2 to Entertainment room	Normal	Normal	Eaves	K, H, J
					Low-E Glass	J
					Rotating hoods	V
					Wall Greening	R, A, J, G
					Casement Window	R, A, J, G, V

Source: authors.

. Because the practical customer’s requirements are randomized, optimal methods and variable methods are applied for customers to adjust the extra factors, daylighting, and ventilation, in the space. Customers can flexibly adjust the carbon emission indicators to improve their interior conditions by changing the location, angle, and arrangement. Applied passive design methods affect the carbon emission indicators proposed in Section 4, such as the window-to-wall ratio, ventilation rate, and effective daylight area, and their relationships are shown in Table 10. The optimal passive design methods are as follows. These passive design methods can be applied in most touristic buildings and areas.

• Eaves

Eaves are applied to adjust the light correction coefficient and effective daylight area. This device takes advantage of natural shades to decrease the daylight. Areas with hotter summers and lower latitudes commonly use this facility to reduce excessive light entering the room.

• Low-E Glass

Low-E Glass can change the effective daylight area of an opening. Low-E Glass is applied to a special coating that increases the light entering the room. It is a widely used enhancement in many buildings.

• Rotating hoods

The rotating hoods mainly affect the ventilation quantity. The working principle of the rotating hoods is to utilize wind power to drive the internal rotating parts so that the air outlet of the hood is always back in the wind direction, thus improving ventilation efficiency. This method can be used in any building that requires ventilation. Wall greening

• Wall Greening

Wall greening can reduce the opening area and affect the window-to-ground ratio, light correction coefficient, and effective daylight area. The leaves block too much natural light in the summer. The leaves fall off in winter, and more light enters the room. Because it is a natural and clean way, it can be used in any area suitable for plants.

• Casement Window

Casement windows are applied to adjust the window-to-ground ratio, light correction coefficient, effective daylight area, and ventilation quantity. This device utilizes the window opening angle to increase the area in contact with direct sunlight and the ventilation area, thereby reducing energy consumption during the day. This facility is typically used in high-latitude, high-rise residential areas that require sunlight. In addition, casement windows are safer and are suitable for rooms for children and the elderly.

Secondly, the variable passive design methods are as follows. These passive design methods can be used in the operating phase to adjust the practical ventilation and daylighting.

• Painting with light-colored materials

Painting with light-colored materials can affect the window-to-ground ratio and effective daylight area. This method increases the amount of light entering a room by changing the color of the coating material and using the diffuse reflection of sunlight. The main applications of this method can be found in the new construction and reconstruction phases. At the same time, due to the characteristics of light-colored paint, it is mainly used in children’s rooms as well as to create a relaxing atmosphere.

• Adjustable sunshade components

The principle of the adjustable sunshade components is the same as the wall greening. They both utilize the shade to reduce the opening area and affect the window-to-ground ratio, light correction coefficient, and effective daylight area. The difference is that adjustable sunshade components can be adjusted flexibly. Therefore, it is widely used in many buildings.

• Transparent or translucent sliding doors

Transparent or translucent sliding doors mainly affect the window-to-ground ratio and effective daylight area. This device utilizes the material’s characteristics to increase the light entering the room. As a result, it increases the illumination of the room. This device is used when there is a need to change the room’s function flexibly.

• Reflecting board

Reflecting boards can affect the effective daylight area. This device improves illumination within the interior by reflecting light, reducing reliance on artificial lighting. Therefore, it is widely used in many buildings.

• Adjustable Reflectors

Adjustable Reflectors work similarly to reflecting boards. Their difference is that Adjustable Reflectors can adjust the reflector’s angle to the sun’s angle in different areas and at different times of the day. As a result, this device is used in rooms that require flexible light adjustments.

• Shutters

Shutters are applied to adjust the window area, the window-to-ground ratio, the light correction coefficient, and the effective daylight area. This device essentially changes the amount of light entering the room by adjusting the angle of the shutters. Therefore, it is widely used in many buildings.

• Adjustable shutter

Adjustable shutters are similar to shutters, but their primary function is ventilation rather than light. The blades of the shutters can be adjusted manually or electrically to precisely control the amount of ventilation and the direction of airflow. Therefore, it is widely used in many buildings.

• Dimmable glass

Dimmable glass is a high-tech dimming device that can change the transparency of the glass through electric fields or temperature changes. By installing dimming glass in light openings, the transmittance of light can be adjusted automatically or manually according to the lighting needs of the room and the intensity of external light.

The practical application of passive design methods in the touristic apartment units is illustrated in Table 11. Table 11 shows the passive design methods applied to each customer cluster and the carbon emission indicators affected.

6. Conclusions and Discussion

This research provides a design strategy to address excessive carbon emissions in the operating phase of touristic apartments due to changes in customer requirements from a dynamic perspective. Past studies have considered openings a key component of constant excessive carbon emissions. However, this approach does not consider changes in ventilation and daylighting requirements during practical use. Therefore, the dynamic and rational design of the opening is very critical. This paper reveals the relationship between major consumer requirement changes and carbon emissions. The study elucidates the dynamic mechanisms affecting carbon emissions in the operating phase of touristic apartments based on the analysis of ventilation and lighting factors.

This research uses four primary customer clusters and a basic touristic apartment unit model based on timeshare property ownership. This paper uses five-dimensional touristic customer requirement modes to analyze the changes in customer requirements. It also analyzes the spatial function changes and two extra factors from the multi-analysis to the customer requirement change in each cluster. We extract six carbon emission indicators to control the excessive carbon emissions in the operating phase; see Table 4 and Table 5. Among these, four leading carbon emission indicators are applied to classify the location and scale of openings. Two more secondary restricted indicators are used to amend the proper opening scales to prevent excessive use. Finally, this study conducts seven zero-carbon touristic apartment unit models for the four customer clusters. In addition, this paper provides five optimal passive design methods and eight variable passive design methods to guide the practical opening design; see Table 10 and Table 11.

Climatic, regional, and cultural factors influence the diversity of the built environment, and the diversity of the built environment influences differences in carbon emissions. Therefore, future research is directed toward exploring the carbon emission factors of the openings and guiding practical design in different climatic zones and regions. Also, discussing how to evaluate the effectiveness of strategies through simulations is a key research context.