Research on Opening Design Guidelines for Zero-Energy House Based on the Family Life Cycle

Abstract

Spatial resources and environmental problems caused by population growth are increasingly becoming the focus of global concern. The environmental sustainability of building products has become the research frontier of the industry. Previous research has proved that 25% of energy consumption comes from daily use, and realizing low-energy design based on the whole life cycle is of great significance to promoting the transformation of the building industry. This paper focuses on the wasteful energy consumption problem caused by the changes in residents’ behavioral requirements due to the changes in family structure. Based on the family life cycle analysis, this paper explores the mechanism of residents’ behavioral requirements and spatial function changes at each stage to clarify the relationship between residents’ behavior and building energy consumption. Then, by controlling factors, including Light Correction Coefficient, Effective Daylight Area, window-to-ground ratio, and window-to-wall ratio, and applying the passive design methodology, this paper establishes the zero-energy home opening design guidelines based on the family life cycle. This research guides designers in the design of zero-energy house openings and, at the same time, provides new perspectives for related research in the field of building energy consumption, which helps to promote the sustainable development of the field of architectural design.

1. Introduction

The world’s growing population and the rapid development of the global economy have led to environmental problems. The construction industry, as a sector directly affected by population growth, is also a significant source of global greenhouse emissions. The Global State of Building and Construction 2022 report shows that CO₂ emissions from the operational phase of the construction industry have reached an all-time peak of approximately 10 Gt CO₂ [1]. In response to the requirements of the Sustainable Development Goals (SDGs), the development of the construction industry is gradually turning from meeting the basic needs of living to the higher goal of solving the problem of living space constraints caused by population growth while at the same time controlling the negative impacts of construction activities on the environment and reducing energy consumption and emissions to realize the long-term sustainability of building products [2]. In the 1970s, the concept of zero-energy buildings (ZEBs) was created and has continued to evolve. ZEBs aim to minimize energy consumption through energy-efficient technologies and renewable energy sources [3,4]. In this background, the study of the factors affecting the energy consumption of buildings and the development of appropriate energy-saving measures to reduce the energy demand of buildings is vital to reducing the environmental impact of buildings. Openings significantly contribute to building energy consumption due to their thermal bridging effect, direct solar heat gain, and glazing area-to-wall ratio [5]. Proper design of residential openings is essential to control the overall energy consumption of a building [6].

Residents’ behavior is one of the most critical factors affecting the energy consumption of buildings [7,8,9,10]. Previous research has proved that 25% of energy consumption comes from daily use, and realizing low energy design based on the whole life cycle is of great significance to promote the transformation of the building industry [11]. Inclusion and exclusion of actual residents’ behavior can lead to significant differences in the energy simulation results of a building. Residents’ behaviors that affect building energy consumption can be divided into three categories: occupancy, interaction, and behavioral efficiency [12]. Therefore, the critical problem of the research is how to accurately analyze the differences in energy consumption caused by different space use needs of the residents to realize the optimal design under the perspective of zero-energy consumption.

How to accurately simulate residents’ behavior has become the focus of building energy simulation and performance evaluation. In the 1950s, the family life cycle (FLC) theory was proposed, which provided ideas for the refined simulation of residents’ behavior [13]. In the early stage, FLC theory analyzed marriage and family relationships’ formation, maintenance, change, and dissolution [14]. Scholars such as J. Doling applied the FLC theory to solve the problem of residential choice in response to changes in family structure [15]. Applying the analysis of Family Structure Changes, sustainable space design is conducted to ensure that the space can meet the changes in family needs at different stages, improve the efficiency of use behavior, and realize the efficient use of space. However, most of the related research focuses on the relationship between changes in requirements of residents at various stages of FLC and residential houses. Research in building energy consumption based on FLC theory still needs to be more extensive. It has yet to be combined with research on new theories and technologies in building energy consumption. Therefore, analyzing residents’ spatial requirements based on the FLC theory can help us to realize an accurate simulation of building energy consumption and propose a design optimization strategy for the opening section of zero-energy buildings.

This study applies the family size change models proposed by Paul Glick and Evelyn Duvall, exploring the changes in occupant spatial needs caused by the changes in family structure [16,17]. The study examines the mismatch between residents’ requirements and spatial functions due to changes in family structure and the increase in energy-consuming behaviors, which include the addition of active equipment and the increased frequency of resource use. In order to achieve this goal, this study first adopts a quantitative approach and the EEM passive design method to adjust the critical parameters in the design of zero-energy housing, including the window-to-ground ratio, light correction coefficient, and effective daylight area, etc., to analyze the relationship between the scale of the openings and the building’s energy consumption, in order to optimize the natural lighting of the housing space at all stages of the FLC, and then propose a strategy for adapting to the lighting demand brought about by the family structure changes [18]. In the process, the study not only focuses on reducing energy consumption in the operation stage of buildings through design but also aims to enhance the sustainability and eco-efficiency of buildings. Therefore, the study’s results provide specific energy design strategies for the construction industry and are significant in promoting the industry’s sustainable development.

2. Methodology

2.1. Research Framework

The research takes the research related to the relationship between the energy consumption of residents and houses as the theoretical basis, analyzes the relationship between the resident’s requirements and the spatial functions at each stage of FLC, and carries out the design of the zero-energy house model. The research process is shown in Figure 1. Secondly, the research used quantitative research methods and analyzed the location, scale, area, and other data on the openings, which affect the energy of residential houses. The research determined the energy-saving area and location of residential openings by controlling the window-to-ground ratio, light correction coefficient, and effective daylighting area, and the opening scale is verified twice by the window-to-wall ratio; finally, zero-energy passive design techniques such as EEM are utilized to target the control of relevant parameters affecting the energy consumption of each stage of the changes in the family structure, to reduce the efficiency of the energy-consuming behaviors of residents in the stages of the family structure, and to form a set of zero-energy residential model design for FLC. The residential model guides the design of zero-energy residential openings, as well as new perspectives on research related to building energy consumption, which helps promote sustainable development in the field of building design.

2.2. Family Life Cycle Theory

The family life cycle (FLC) is a theoretical framework that describes the formation, maintenance, change, and dissolution of marriage and family relationships. In the 1950s and 1960s, scholars further identified and defined the FLC stages, meticulously analyzing consumption behaviors corresponding to these stages and proposing corresponding theoretical models. According to the theoretical model of FLC proposed by Paul Glick and Evelyn Duvall, the development of the family can be classified into five major stages, shown below, each of which has its own specific needs and corresponding behavioral patterns.

• Beginning families;
• Family extension;
• Family extension;
• Families in the middle years;
• Aging families.

Beyond sociology and economics, FLC has been applied in numerous research fields. Some scholars introduced the concept of FLC in sociology, further defined the stages of FLC based on the comprehensive concept of family, and socialized the differentiation of the characteristics of different countries and regions [19]. Urban planning and architecture have earlier introduced FLC theory into their research to help predict and plan the spatial requirements of families at different life cycle stages and to enhance the flexibility and adaptability of living space design to effectively adapt to the evolution of family structure and requirements [20]. Lansing and other scholars applied FLC as the analytical foundation to investigate the relationship between changes in family income and expenditures at different stages of the process [21]. J. Doling and other scholars, based on Lansing’s study, further explored the relationship between changes in family size at different stages of the process and changes in requirements for homeownership and requirements for living space [15]. In 1982, William J. et al. explored the relationship between changes in family structure and residential preferences based on FLC and the relationship between family composition and residential mobility decisions [22,23,24]. P.B. et al. analyzed housing consumption patterns and location in FLC using a sample of homebuyers in Perth, Western Australia [25,26]. Valerie Preston et al. explored the effects of FLC on residential neighborhood attributes [27]. The practice of FLC theory in urban and rural planning, architecture, and other professions has gradually increased, becoming a guideline and theoretical basis for solving actual social and practical problems. However, most of the related research focuses on the relationship between changes in requirements of residents at various stages of FLC and residential houses, and there needs to be more research on guiding the design of residential houses directly based on changes in requirements.

Currently, in the background of severe environmental problems, research related to building energy consumption is developing gradually [28]. Furthermore, related research shows that the number of residents and their related behavioral responses to requirements are essential factors affecting the energy consumption of buildings. In the 1980s, David J. Fritzsche began to explore the energy consumption at each stage of the cycle with FLC as the independent variable [29]. Frey, Cynthia J compared the energy consumption and savings at each stage of FLC [30]. Gregory et al. explored life cycle energy, costs, and related strategies for improving single-family homes [31]. However, research in building energy consumption based on FLC theory is still relatively scarce. It has yet to be combined with research on new theories and technologies in building energy consumption. Therefore, based on FLC, it is a new direction for research in this field to explore the impact of residents’ demand changes on building energy consumption at different stages of family structure changes and how to apply new technologies such as passive design for ZEB design, which puts forward a new perspective for exploring the use of energy consumption in buildings [32]. At the same time, it has greater significance for developing the theory of FLC-related research.

3. Analysis of Residents’ Behavioral Requirements and House Space Organization Based on Family Life Cycle

3.1. Analysis of Residents’ Behavioral Requirements at Various Stages of Family Structure Changes

Based on the theoretical research related to residents and building energy consumption, to effectively reduce building energy consumption, it is necessary to discuss the changes in residents’ behavioral needs in terms of occupancy, interaction, and behavioral efficiency at each stage of the family structure change. The research is based on analyzing the residents’ family structure changes and their behavioral tendencies in its five main stages according to the FLC theoretical model and classifying their requirements into three categories based on the frequency of their behaviors in the house: basic, auxiliary, and composite requirements, as shown in

Table 1. Changes in residents’ behavioral requirements at various stages of the family life cycle.

Stages of Family Development	Basic Requirements	Auxiliary Requirements	Composite Requirements
Beginning families	Residential requirement	Bath requirements, dressing requirements, cleaning requirements, meeting requirements, storage requirements	-
Family extension	Increased requirements for the number of residential spaces	Bath requirements, dressing requirements, cleaning requirements	Increased space requirements for children’s use
Families as launching centers	Children’s independent residence requirements	Bath requirements, dressing requirements, cleaning requirements, meeting requirements	Increased requirements for the area of meeting space
Families in the middle years	Children’s independent residence requirements, decreased frequency of children living in the space		Increased demand for activity space
Aging families	Expanded requirements for residential space	Bath requirements, dressing requirements, cleaning requirements	Increased requirements for the use of space by caregivers

Source: Author.

.

• Basic Requirements: Refers to the primary activities, i.e., residential behaviors performed by residents in a housing unit in response to occupancy relationships.
• Auxiliary Requirements: Complementary to basic needs, i.e., the basic interactive behaviors that occur in a building after the residents have completed their occupancy behaviors.
• Composite Requirements: Activities that residents engage in occasionally in the house, i.e., other interactions that may occur after residents have satisfied primary occupancy and interaction behaviors. Composite requirements reflect the other functions that residents may perform in the house. Moreover, the choice of that requirement is phased and uncertain. Therefore, the quantity and frequency of satisfying the residents’ composite requirements reflect the efficiency of the residents’ behavior with the residents.

3.2. Correspondence between Residents’ Behavioral Requirements and Spatial Functions at Various Stages of the Life Cycle

The research summarizes the behavioral requirements shared by residents at each stage of the FLC and analyzes the interaction between the behavioral requirements of the above three types of residents and space and corresponds with the functions of zero-energy houses to determine the spatial types of the houses, as shown in

Table 2. Correspondence between the residents’ behavioral requirements at various stages and spatial functions.

Residents’ Behavioral Requirements	Basic Requirements	Auxiliary Requirements					Composite Requirements
							Family Extension	Aging Families
Full-stage	Residential Requirement	Bath requirements, dressing requirements, cleaning requirements, meeting requirements, storage requirements					-
Family Extension							Increased space requirements for children
Aging families							Increased space requirements for caregivers
Function	Residential Function	Dressing Function	Bath Function	Cleaning Function	Meeting Function	Storage Function	Children Use Function	Caregiver Use Function
Space	Bedroom	Dresser	Shower	Restroom	Living room	Cloakroom	Children room	Caregiver room

Source: Author.

and

Table 3. Statistics of spatial functions and characteristics of the zero-energy house at the Beginning Families stage of residents’ family structure formation.

No.	Space Name	Function	Space Module Relationship
①	Bedroom	Residential Function	4n
②	Cloakroom	Clothing storage Function	2n
③	Living room	Meeting Function	3n
④	Bath space	Bath Function, Dressing Function, Cleaning Function	3n
⑤	Shower	Bath Function	n
⑥	Dresser	Dressing Function	n
⑦	Buffer space	Articulation of other spaces	n
⑧	Restroom	Cleaning Function	n

Source: Author.

. At the same time, the research summarizes the zero-energy house space and its characteristics based on the correspondence between residents’ behaviors and space functions. Based on the FLC theory, the cycle begins at the Beginning Families stage. Therefore, the research takes the Beginning Families stage as an example, and based on the human body scale, according to the frequency of the residents’ behaviors appearing in the residence, the space used by the composite demand as the smallest unit of the spatial unit n. Furthermore, through the multiplicative relationship, it reacts to the frequency of the behaviors to serve as a functional basis for the floor plan design of a zero-energy house.

3.3. Beginning Families Stage Zero-Energy House Organization

The research applies the zero-energy building EEM technology, based on the above analysis of the function of the residential space, with the lighting, ventilation, and other factors affecting the energy consumption as a reference. At the same time, the research combines passive design with the relationship between spatial functions and factors affecting building energy consumption, the residents’ habits of using the space, and spatial interaction behaviors,

Table 4. Correspondence table between spatial functions of the zero-energy house in the Beginning Families Stage and each influencing factor.

No.	Name	Spatial Functions	Factors Affecting Energy Consumption	Types
①	Bedroom	Residential Function	High lighting and ventilation requirements	Served space
②	Cloakroom	Clothing Storage Function	No lighting and ventilation requirements	Service space
③	Living room	Meeting Function	High lighting and ventilation requirements	Served space
④	Bath space	Bath Function, Dressing Function, Cleaning Function	Lower lighting requirements, higher ventilation requirements	Service space
⑤	Shower	Bath Function	Lower lighting requirements, higher ventilation requirements
⑥	Dresser	Dressing Function	High lighting requirements
⑦	Buffer space	Articulation of other spaces	No lighting and ventilation requirements
⑧	Restroom	Cleaning Function	Lower lighting requirements, higher ventilation requirements

Source: Author.

, and organically integrates and lays out the zero-energy house space based on the theory of service space and served space. Figure 2 is a schematic diagram of a typical house space layout drawn based on the above analysis.

3.4. Residents’ Spatial Function Changes Based on the Family Life Cycle

According to FLC theory, residents have different requirements and interaction behaviors during family structure changes. Therefore, to reduce the residents’ behavioral efficiency and building energy consumption, the research needs to analyze the spatial functional changes caused by the interaction behavior changes at each stage. After that, the research analyzes the above change impact on the factors affecting energy consumption based on the lighting requirements, as shown in

Table 5. Changes in space and functions at various stages of the family life cycle.

Stages of Family Development	Layout	Function Changes	New Space	Area Changes	Additional Need for Light	Openings Layout Requirements
Beginning families		-	-	-	-	High natural lighting requirements
Family Extension		Checkroom to children’s room	No	No changes	Yes	High natural lighting requirements
Families as launching centers		Checkroom merged with Living room	Yes	Increase	No	High natural lighting requirements
Families in the middle years
Aging families		Checkroom merged with bedroom	Yes	Slight increase	No	High natural lighting requirements
		Checkroom to caregiver room	No	No changes	Yes	Low natural lighting requirements

Source: Author.

. The final research summarizes the requirements for arranging the openings based on the relationship of influence. The spatial function changes at each stage and the changes in lighting requirements are analyzed as follows:

• Beginning families

This stage begins when the residents get married and ends with the birth of the residents’ first child. In this stage, the residents’ family is in the initial establishment stage, so the spatial function design must consider the requirements of the whole cycle and its spatial function is shown in Section 3.3.

• Family Extension

This stage begins with the birth of the first child and ends with the birth of the last child. In this stage, the core family members change from couples to children, and the residential requirements increase accordingly. The above changes mean that in addition to meeting the residential requirements of the couple, it is also necessary to consider the residential requirements of the children and the independence of the requirements. Consequently, the checkroom is converted into a children’s room and separated from the parent’s room to ensure the independence of the children’s residence while facilitating the parents’ care.

• Families as launching centers and families in the middle years

The requirements of Families as launching centers and Families in the middle year stages are similar, so the two stages are analyzed together. Families as launching centers stage, for example, begins with the birth of the last child and ends with the departure of the first child from the parental home. In this stage, the family structure begins to shrink, and the gravity of the core family members shifts from the children to the couples. Currently, couples need to transfer the space requirements to themselves, and their recreation and entertainment requirements are increased. Therefore, at this stage, the checkroom is merged with the living room to increase the space and meet the leisure and entertainment requirements.

• Aging families

This stage begins with the death of one of the spouses and ends with the death of the other spouse. In this stage, the residents are becoming older and less mobile, and the requirement for convenience and comfort in behavioral activities increases. Consequently, at the beginning of this stage, more space is needed for activities, so the checkroom is combined with the bedroom to facilitate the occupants’ activities. Furthermore, at the end of this stage, the residents’ behavioral aids are elevated. Thus, the function of the checkroom is changed to that of a caregiver room to facilitate the care of the residents.

4. Analysis of Openings Based on Residents’ Behavioral Requirements Changes

4.1. Openings Layout for Zero-Energy Houses

The research identifies the space changes at each family structural change stage based on the above FLC analysis of spatial functional changes and spatial lighting needs. In order to adapt lighting requirements and spatial function changes,

Table 6. The number and space area changes of openings in zero-energy houses.

Stages of Family Development	No.	Name	Aera	The Openings
Beginning families	①	Bedroom	No changes	Exterior door A
Family Extension
Families as launching centers
Families in the middle years
Aging families (Stage 1)			Increase	Window A
Beginning families	②	Cloakroom	No changes	Interior Door A
Family Extension		Children room
Families as launching centers		-	Functional replacement	Window E
Families in the middle years
Aging families (Stage 1)
Aging families (Stage 2)		Caregiver room	No changes
Beginning families	③	Living room	No changes	Exterior door B
Family Extension				Window B
Families as launching centers		Living room	Increase	Interior Door B
Families in the middle years
Aging families		Living room	Decrease
All stages in family life cycle	④	Bath space	No changes	Window C
				Window D
				Interior Door A
				Interior Door B
				Sliding Door A
				Sliding Door B
All stages in family life cycle	⑤	Shower	No changes	Window C
				Sliding Door A
All stages in family life cycle	⑥	Dresser	No changes	Sliding Door A
	⑦	Buffer space	No changes	Interior Door B
All stages in family life cycle	⑧	Restroom	No changes	Window D
				Sliding Door B

Source: Author.

, it is necessary to meet each stage‘s direct lighting requirements in the initial design, i.e., to determine the number of openings and locations in zero-energy homes at the Beginning Families stage, as shown in Figure 3. In addition, the research also calculates the space area before and after the change based on the relationship for the spatial function change, which provides a foundation for controlling the spatial lighting quantity change.

4.2. Parametric Control of the Zero-Energy House Opening Scales

Based on the above spatial function changes at each stage of FLC, the research summarizes the opening factors that affect building energy consumption at each stage. In order to reduce the energy consumption after the change of space function, it is necessary to control the size of the openings based on the location and the light requirement of the residents’ behavior. The research begins with a window-to-ground ratio that measures whether the incoming light initially meets the lighting requirements of that room in order to control the specific sizes of the building openings, as shown in

Table 7. Zero-Energy House Opening Scales Control Table.

No	Name	Space Aera	Openings	Scales	Aera	R		k			J
						Data	Standard Data	Data		Standard Data	Data		Enhancement Ratio
①	Bedroom	4n	Exterior door A	900 × 2100 mm	1.89 m2	-	-	-	-	-	-	More than 1.41 m2	1.28
			Window A	2100 × 2100 mm	4.41 m2	0.447	1/6~1/8	6D/2.815-1.4	2.13D-1.4	More than 0.73	3.2193 m2
⑨	Cloakroom	2n	Interior Door A	800 × 2100 mm	1.68 m2	-	-	-	-	-	-	More than 0.63 m2	2.97
	Children room
	Caregiver room
			Window E	450 × 1500 mm	0.675 m2	0.152	1/6~1/8	-	-	More than 0.73	-	More than 1.41 m2	-
②	Living room	3n	Exterior door B	900 × 2100 mm	1.89 m2	-	-	-	-	-	-	More than 1.04 m2	5.44
			Window B	2400 × 1500 mm	3.6 m2	0.495	1/6~1/4	6D/1.84-1.4	3.26D-1.4	More than 1.86	6.696 m2
			Interior Door B	800 × 2100 mm	1.68 m2	-	-	-	-	-	-
④	Bath space	3n	Window C	450 × 1500 mm	0.675 m2	0.123	Not less than 1/6	6D/0.707-1.4 Or 6D/0.34-1.4	8.57D-1.4 Or 17.65D-1.4	-	2.025 m2	More than 1.57 m2	1.58
			Window D	450 × 1500 mm	0.675 m2						2.025 m2
			Interior Door A	800 × 2100 mm	1.68 m2	-	-	-	-	-	-
			Interior Door B	800 × 2100 mm	1.68 m2	-	-	-	-	-	-
			Sliding Door A	800 × 2100 mm	1.68 m2	-	-	-	-	-	-
			Sliding Door B	800 × 2100 mm	1.68 m2	-	-	-	-	-	-
⑤	Shower	n	Window C	450 × 1500 mm	0.675 m2	0.139	Not less than 1/6	6D/0.707-1.4	8.57D-1.4	3	2.025 m2	More than 0.69 m2	1.93
			Sliding Door A	800 × 2100 mm	1.68 m2	-	-	-	-	-	-
⑥	Dresser	n	Sliding Door A	800 × 2100 mm	1.68 m2	-	-	-	-	-	-	More than 0.44 m2	Indirect lighting
⑦	Buffer space	n	Interior Door B	800 × 2100 mm	1.68 m2	-	-	-	-	-	-	More than 0.21 m2
⑧	Restroom	n	Window D	450 × 1500 mm	0.675 m2	0.561	Not less than 1/6	6D/0.34-1.4	17.65D-1.4	3	2.025 m2	More than 0.17 m2	10.91
			Sliding Door B	800 × 2100 mm	1.68 m2	-	-	-	-	-	-

Source: Building Design Sourcebook.

.

R = A/S

R: Window-to-ground Ratio. A: Window opening (m²). S: Space scale (m²).

Secondly, the research calculates the Effective Daylight Area to satisfy the interactive behavior in that space through the Light Correction Coefficient to improve energy efficiency and reduce energy consumption.

K = 6 × D/H-1.4

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 +⋯⋯+ KnAn.

J: Effective Daylight Area.

Openings scale based on the JISA to take the standard residential opening modulus for the product calculation; each space’s residential area according to Section 3.2; each room‘s size takes the average of the typical residential plane samples, takes the average of the sample area of the bathroom plane for n.

The research quantitatively controls the opening scales in the resident’s behavioral activity space so that the openings meet the uniform lighting requirements. Simultaneously, research controls the opening scales to meet the lighting requirements of the residents’ interactive activities in the space and to reduce the heat loss and the residents’ behavioral efficiency, thus reducing the energy consumption of the building. However, the opening heat loss cannot be determined to be the lowest through the above parameters. Hence, the research carries out the secondary measurement of the window scale through the window-to-wall ratio to verify the reasonableness of the scales to control the energy consumption further,

Table 8. Zero-energy house window-to-wall ratio control table.

No.	Name	The Openings	Scales	Aera	Façade Area	G
						Data	Standard Data	Enhancement Ratio
①	Bedroom	Window A	2100 × 2100 mm	4.41 m2	12.814 m2	0.344	Less than or equal to 0.35	0.017
②	Living room	Window B	2400 × 1500 mm	3.6 m2	20.04 m2	0.18	Less than or equal to 0.25	0.28
③	Bath space	Window C	450 × 1500 mm	0.675 m2	24.48 m2	0.055	Less than or equal to 0.3	0.82
		Window D	450 × 1500 mm	0.675 m2
⑤	Shower	Window C	450 × 1500 mm	0.675 m2	6.72 m2	0.1		0.667
⑧	Restroom	Window D	450 × 1500 mm	0.675 m2	17.76 m2	0.038		0.873

Source: Author.

. In addition, the research defaults to a flat roof to avoid the influence on lighting and energy consumption due to changes in the building’s shape. In conclusion, the research determines the scales and area of the opening through the Light Correction Coefficient and effective Daylight Area. Further, it verifies the opening scale’s reasonableness through the window-to-wall ratio to complete the zero-energy house opening design, as shown in Figure 4.

G = A/F

G: Window-to-wall ratio. F: Building unit façade area.

5. Opening Design Strategy

The research determines the reasonable scale and area of zero-energy house openings through parameters such as window-to-ground ratio, light correction coefficient, and effective daylight area to ensure that the opening design meets the requirements of residents’ interactive behaviors in different spaces. However, due to the randomness of the residents’ interactive behaviors in the space, it is necessary to control the opening energy consumption by adopting passive design methods according to the spatial functions changes at each stage of the FLC as well as the factor changes affecting the energy consumption in order to reduce the efficiency effectively, as shown in

Table 9. Correspondence between passive design techniques and mechanisms affecting energy consumption factors.

EEM Technology	Category	Factor Changes
		R	A	S	K	D	H	J	G	F
Eaves	Optimal control method	-	-	-	↓	-	↓	↓	-	-
Low-E Glass		-	-	-	-	-	-	↑	-	-
Wall Greening		↓	↓	-	-	-	-	↓	↓	-
Casement Window	Variable control method	↑	↑	-	-	-	-	↑	↑	-
Adjustable Reflector		-	-	-	-	-	-	↑	-	-
Light-Colored Material Painting		↑	-	-	-	-	-	↑	-	-
Adjustable Exterior Sunshade Components		↓	↓	-	-	-	-	↓	↓	-
Translucent Space Partition		↑	-	-	-	-	-	↑	-	-

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

and

Table 10. Energy Design Strategies for Zero-Energy House Openings at Various Stages of FLC.

Stages of Family Development	Layout	Function Changes	Space Maintenance	Space Separation	Openings Layout Requirements	Passive Design Methods	Factors
Beginning families		-	-	-	High natural lighting requirements	Adjustable Reflector	J
						Adjustable Exterior Sunshade Components	R, A, J, G
						Eaves	K, H, J
						Low-E Glass	J
						Wall Greening	R, A, J, G
						Casement Window	R, A, J, G
Family Extension		- Checkroom to children’s room	No changes	-		Adjustable Reflector	J
						Translucent space partition	R, J
Families as launching centers		Checkroom merged with Living room	Removal of the checkroom side wall	Movable and assembled deformed door		Adjustable Reflector	J
Families in the middle years						Light-colored material painting	R, J, G
Aging families		Checkroom merged with bedroom -	Removal of the checkroom on the other side wall	Movable and assembled deformed door		Adjustable Reflector	J
						Light-colored material painting	R, J, G
						Translucent space partition	R, J
		Checkroom to caregiver room	No changes	-	High natural lighting requirements	Adjustable Exterior Sunshade Components	R, A, J, G

Source: Author.

. By freely adjusting the arrangement, position, and form of the components, the residents can control and adjust the window-to-ground ratio, light correction coefficient, effective lighting area, and other parameters to meet the requirements of interactive behaviors, thus reducing energy consumption. Based on the FLC Beginning Families Stage, the research needs to synthesize the full-cycle resident behavioral requirement changes, utilize the optimal passive technologies and components, and summarize the optimal control methods. The technologies applied in this stage are as follows:

• Eaves

Using eaves to block excessive solar radiation in the summer mainly reduces the light correction factor and effective light area to avoid excessive heat. It is generally used in areas with hotter summers and lower latitudes.

• Low-E Glass

Utilizing Low-E glass coating increases the effective daylight area and has a wide range of applications.

• Wall Greening

Installation of appropriate wall greenery can reduce the amount of solar jurisdiction on the wall through foliage shading to regulate the effective daylight area and avoid overheating in the summer, resulting in elevated indoor temperatures. It does not apply to urban renewal or renovation.

• Casement Window

House openings adopt the casement windows, using the window opening angle to increase the contact area with direct sunlight and improve the effective daylight area, window-to-wall ratio, and window-to-ground ratio, thereby reducing daytime energy consumption. It is generally used in high-latitude, high-rise residential areas that need sunlight.

Second, the research sets up adjustable components based on changes in residents’ behavioral requirements and energy consumption factors. The research changes the parameters through the residents’ active adjustment and control to flexibly reduce the energy requirements and energy consumption during the operation. The adjustable components that can be applied are shown below:

• Adjustable Reflector

Adjusting the angle of the reflector according to the angle of the sunlight in different areas and at different times can adjust the effective daylight area with a wide range of applications.

• Light-Colored Material Painting

Changing the coating material’s color, using diffuse reflection of sunlight, can adjust the effective daylight area and window-to-floor ratio. The application scope is more flexible and can be used in the new construction and reconstruction stages.

• Adjustable Exterior Sunshade Components

According to the residents’ requirements for indoor light, the residents can adjust the amount of light intake by changing the angle of adjustable exterior sunshade components and changing the effective daylight area, light correction coefficient, window-to-floor ratio, and window-to-wall ratio. The application scope is broad.

• Translucent Space Partition

Adjusting the translucent space partition’s position can change the space through which the light passes to adjust the window-to-ground ratio and the effective daylight area, which has a broader application scope.

6. Conclusions

This paper provides a practical design guideline for designers to reduce the energy consumption of buildings. Applying FLC theory, this paper unveils the relationship between residential behavior changes and energy consumption at each FLC stage. It elucidates the mechanism between the behavioral requirements changes and the energy consumption changes. Research has found that changes in energy consumption at different FLC stages are mainly influenced by the requirements changes for lighting and ventilation of the space. Therefore, the rational design of the opening section is very critical. Using the EEM passive methods, the research establishes the basic model and zero-energy houses opening design guideline for each FLC stage.

The guideline in this paper is proposed based on the resident’s behavioral activity requirement criteria. The opening scale that meets the resident’s behavioral requirement changes identified by applying the window-to-ground ratio, light correction coefficient, and effective daylight area. Meanwhile, a secondary verification of the opening scale was conducted by applying the window-to-wall ratio. The guideline proposes that by applying eaves, Low-E glass, wall greening, and casement windows, the energy consumption of all FLC stages can be controlled. For the Beginning families, applying adjustable sunshade components, reflective panels, material painting, and translucent space partition, the energy consumption factors can be flexibly adjusted and controlled to adapt to the dynamic requirement changes in Family Structure Changes, and to reduce the energy consumption caused by the uncertainty of the residents’ behaviors.

For future research, climatic, regional, and cultural factors contribute to the diversity of the built environment. The diversity of built environments affects energy consumption differences. Therefore, future research directions explore the energy consumption factors of building openings and guide the practical design in different climate zones and regions. Meanwhile, discussing how to test the validity of strategies by simulating is also critical research content in the future.