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Design Strategies and Energy Performance of a Net-zero Energy House Based on Natural Philosophy


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This paper presents the design strategies and energy performance of a net-zero energy house (NZEH), Nature Between, which was designed and built to participate in the Solar Decathlon China 2018 competition. The specific parts of the design strategies for Nature Between, including architectural concept, materials, passive strategies and active strategies, are introduced and analyzed. This study includes a discussion of the building’s energy performance based on the measured data gathered in Dezhou, where the competition was held. And also the annual energy simulation using Energyplus software based on the climate of Xiamen, where the prototype was located in. The results show that the design strategies are reasonably applied in Nature Between to achieve the goal of zero energy consumption in Dezhou and Xiamen. Pleasant indoor environment and flexible spaces are achieved in the house using natural material, which embodies the concepts of sustainability and natural philosophy. The practical strategies provided in this paper could help the architecture designs for residential NZEH.
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Journal of Asian Architecture and Building Engineering
ISSN: 1346-7581 (Print) 1347-2852 (Online) Journal homepage:
Design Strategies and Energy Performance
of a Net-zero Energy House Based on Natural
Feng Shi, Shaosen Wang, Jinjin Huang & Xiaoqiang Hong
To cite this article: Feng Shi, Shaosen Wang, Jinjin Huang & Xiaoqiang Hong (2019): Design
Strategies and Energy Performance of a Net-zero Energy House Based on Natural Philosophy,
Journal of Asian Architecture and Building Engineering, DOI: 10.1080/13467581.2019.1696206
To link to this article:
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Institute of Japan, Architectural Institute of
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Publisher: Taylor & Francis & The Author(s). Published by Informa UK Limited,
trading as Taylor & Francis Group on behalf of the Architectural Institute of Japan,
Architectural Institute of Korea and Architectural Society of China.
Journal: Journal of Asian Architecture and Building Engineering
DOI: 10.1080/13467581.2019.1696206
Design Strategies and Energy Performance of a Net-zero
Energy House Based on Natural Philosophy
Feng Shi 1,*, Shaosen Wang 2, Jinjin Huang 3, Hong, Xiaoqiang 4
1 Associate Professor, School of Architecture and Civil Engineering, Xiamen University, Xiamen
361005, China,, * Corresponding author
2 Professor, School of Architecture and Civil Engineering, Xiamen University, Xiamen 361005,
3 Post Graduate Student, School of Architecture and Civil Engineering, Xiamen University,
Xiamen 361005, China,
4 Assistant Professor, School of Architecture and Civil Engineering, Xiamen University, Xiamen
361005, China,
This paper presents the design strategies and energy performance of a net-zero
energy house (NZEH), Nature Between, which was designed and built to participate
in the Solar Decathlon China 2018 competition. The specific parts of the design
strategies for Nature Between, including architectural concept, materials, passive
strategies and active strategies, are introduced and analyzed. This study includes a
discussion of the building’s energy performance based on the measured data gathered
in Dezhou, where the competition was held. And also the annual energy simulation
using Energyplus software based on the climate of Xiamen, where the prototype was
located in. The results show that the design strategies are reasonably applied in Nature
Between to achieve the goal of zero energy consumption in Dezhou and Xiamen.
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Pleasant indoor environment and flexible spaces are achieved in the house using
natural material, which embodies the concepts of sustainability and natural philosophy.
The practical strategies provided in this paper could help the architecture designs for
residential NZEH.
Key words: Design strategies; Energy performance; Solar Decathlon; Net-zero
energy house; Dynamic shading
1. Introduction
This paper describes the design strategies of a net-zero energy solar house,
Nature Between, which was designed and built to participate in the 2018 Solar
Decathlon China Competition in Dezhou. This house is the work of a collaborative
team, named Team JIA+, which is made up of students from Xiamen University of
China, Team Solar Bretagne of France, and Shandong University of China. Consent
agreement was signed by all the groups in the team to clarify the rights and
responsibilities of each part. More than 100 students with different majors worked on
this project for two and a half years to build a single-family wooden house that
combines the traditional Chinese building style with innovative energy-efficient
The Solar Decathlon competition is an international collegiate competition
focusing on solar building technologies, which was launched by the U.S. Department
of Energy (DOE) in 2002. Solar Decathlon China 2018 (SDC2018) was organized by
the China Overseas Development Association and Dezhou Municipal People’s
Government, with the authorization of the DOE and with the guidance of the Chinese
National Energy Administration. It challenged collegiate teams to design, build and
operate full-size, solar-powered houses that are energy-efficient and attractive [1]. The
scoring system of the competition was divided into ten parts, including five subjective
rating items scored by jury evaluation: Architecture, Market Appeal, Engineering,
Communication, and Innovation; and five objective items scored by measurement:
Comfort Zone, Appliances, Home Life, Commuting and Energy Performance. The
scoring system allowed for a comprehensive evaluation of the project from the aspects
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of design, technology and sustainability.
The term “Zero Energy House” was proposed by Torben V.Esbensen in 1976 [2].
Since then a lot of studies have been conducted on different aspects of the subject,
such as design strategies [3-5], new material [6], technologies choices [7] and energy
performance [8]. DOE introduced the concept of net-zero energy house and promoted
it by hosting Solar Decathlon competitions. The practice of NZEH gradually spread to
many areas with different climatic conditions [9-11].
Because of the comprehensive and interdisciplinary character of Solar Decathlon
competitions, many studies were carried out based on the houses built in the
competition. Some research papers focused on solar energy technologies, such as new
photovoltaic and solar thermal technologies [12-15] and building integrated
photovoltaic (BIPV) design strategies [16-18]. Research on the application of energy
efficient HVAC equipment [19-21] and new materials such as PCM materials [22-23]
were also becoming popular. Other studies focused on the integration of various
energy efficient technologies [24-27], as well as passive design strategies to reach the
net-zero energy goal [28-31]. The performance of Solar Decathlon houses has also
been discussed in many articles, including indoor thermal comfort [32], lighting
environment [33], energy performance [34-36] and electrical systems [37].
Due to the scoring system of Solar Decathlon China 2018, innovation was highly
valued. Many new technologies and new materials were used in the competition, and
some houses used design strategies to address social problems and reflect regional
characteristics. This paper describes the unique approach used by Nature Between to
achieve zero energy consumption.
2. Design strategies of Nature Between
2.1 Architectural concept
Design, preparation, and prebuild of Nature Between were carried out on the
campus of Xiamen University. The building area is 138 m2, including one living room,
one dining room, two bedrooms, one kitchen, one bathroom and one study room on
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the second floor. The design of the house is based on the climate of Xiamen and the
summer climate of Dezhou. It won two of the ten rating items in the competition,
namely, Home life and Electric car. Fig. 1 and Fig. 2 show a photograph and the floor
plan of Nature Between, respectively.
The architectural concept of Nature Between is targeted for an old house in an
urban or rural village that needs to be transformed into a better living space for a more
comfortable life. The proposed base site of the prototype is a traditional Chinese style
house near Xiamen University, as shown in Fig. 3. This style is named Minnan Dacuo,
or quadrangle dwelling, in South Fujian District. A small courtyard lies in the middle
of the house, surrounded by four rooms. The main room lies on the north of the
courtyard and was retained in the design. By analyzing the relationship between the
form of the house and the surrounding environment, it was proposed to demolish the
three rooms and the courtyard in the south and build a new house in front of the main
room. This new house would share energy, space and social relations with the old one,
and coordinate with the surrounding houses. Then, the new house would be integrated
with the old one to form a better living environment. The spaces inside and between
the two houses would produce diverse spatial experiences for the inhabitants. Fig. 4
describes the design process of Nature Between.
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Fig. 1. Photograph of Nature Between
Fig. 2.
Fig. 2. Floor Plan of Nature Between
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Fig. 3. Base Site of the Prototype
Fig. 4. Design process for Nature Between. (a) The old house in need of renovation in an urban village. (b)
Demolish the three rooms on the south side and build a new house. (c) Lower the roof on the north side and install
high windows for lighting and ventilation. (d) Create a gallery yard on the south side of the house for shading and
sharing. (e) Install photovoltaic panels on the south side of the roof and create an inner yard in the middle of the
The design of the house is based on the concept of natural philosophy, which
means that natural resources are used in many aspects of the building. Natural
philosophy includes three parts: natural living spaces, natural materials and resources,
and natural family relationships.
The architectural design combines a traditional Chinese courtyard with
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innovative, energy-efficient technologies to create natural living spaces. Similar to
traditional Chinese style architecture, courtyards are used in different parts of Nature
Between, namely, the gallery yard in front of the house, the courtyard between the
new house and the old house, and the inner yard located in the center of the new
house. The yards act as green spaces that allow the inhabitants to enjoy nature, and
work as buffer spaces to adjust the natural lighting and natural ventilation of the
Natural materials are used in most parts of the house. Wood is used as the
structural framework and the indoor decoration. Straw is used inside the walls for
thermal insulation. Bamboo is used in outdoor folding doors and for shading.
Rainwater recycling and water reuse technologies are used for water conservation.
A natural and harmonious family relationship is also one of the goals of the
design. Several communication spaces in the house are designed to be shared by the
inhabitants, such as the dining room, with a large table for eight people, that faces the
old house. This room can be used as a dining room and as a sharing space for the
family. It is available for the older people living in the old house to eat and
communicate with the younger people living in the new house.
2.2 Materials
Materials are carefully chosen for each part of the house to make it more
sustainable and easily built by the students. Table 1 presents the structural hierarchies
of different parts of the building envelope and their thermal parameters.
2.2.1 Wood
As a traditional Chinese building material, wood is widely used in China and
easy to build. To make it easier for the students to build the house, and to avoid
thermal bridges, the whole structure is made of wood and OSB panels, which are
natural, recyclable, nontoxic, carbon-sink materials. Birch plywood is used for interior
finishes, which is more environmentally friendly than PVC materials for a
prefabricated building.
Building Structural Hierarchy U Value
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component (m2*K/W)
Outside Wall 12 mm facing panel + 38*38 mm wool keel + waterproof layer + 18 mm OSB
panel + 350 mm compressed straw panels + One-way breathable waterproofing
membrane + 18 mm OSB panel + 12 mm facing panel
Inside Wall 12 mm facing panel + 12 mm OSB panel + 140 mm compressed straw panels +
12 mm OSB panel + 12 mm facing panel
Floor Waterproof layer + 18 mm OSB panel + 350 mm compressed straw panels +
One-way breathable waterproofing membrane + 18 mm OSB panel + 38*38 mm
wool keel + 12 mm facing panel
Roof FRP waterproof + 18 mm OSB panel + 120 mm compressed straw panels + 230
mm glass wool + One-way breathable waterproofing membrane + 18 mm OSB
panel + 38*38 mm wool keel + 12 mm facing panel
Door and
Low-E triple-layer hollow glass filled with argon: 5L+14Ar+5L+14Ar+5L 0.8
Skylight Inner laminated glass, outside tempered glass, middle 12 mm air layer:
Table 1. Structural hierarchy of building envelope and the U value
2.2.2 Straw insulation
Straw is an agricultural byproduct that is readily available in rural China.
Compressed straw panels are used in the building for their good thermal insulation
properties and good acoustic performance. They are also cheap, easy to process, and
perfectly recyclable. In rural areas of China, straw is usually burned, causing air
pollution. However, in Nature Between, straw is compressed into panels without any
add-on, which carries no risk to the health of the builders or the inhabitants and is
more efficient for fireproofing.
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Fig 5. Construction of the timber wall
2.2.3 Phase change material (PCM)
For the convenience of disassembly and transportation, most houses in the Solar
Decathlon use light materials in walls with poor thermal stability. Therefore, the
houses have difficulty in resisting the impact of outdoor climate change. To address
this problem, phase change materials with a phase transformation point at 23°C are
used in the sidewalls of the inner yard of Nature Between. The heat storage capacity
of the materials is used to achieve a more stable air temperature in this unconventional
2.2.4 Other materials
Bamboo: Bamboo is used in the folding doors of the gallery yard, which are
similar to traditional Chinese-style folding doors, and also as a dynamic shading
facade for the building.
Windows: Low-E triple-pane hollow glass is used for the doors and windows of
Nature Between. Vacuum glass is used for the two outside layers of the glass, and the
hollow layers are filled with argon gas.
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2.3 Passive strategies
2.3.1 Climate analysis
Nature Between is designed by integrating low-tech and high-tech technologies
using the key elements of bioclimate architecture, such as shading, natural ventilation,
natural lighting, and rainwater recycling. The house is able to regulate its air
temperature, humidity, air quality, lighting, acoustic and other comfort aspects in a
passive way. The design strategies are based on the climate of Xiamen and the
weather in Dezhou in August for the competition.
Fig. 6 shows the bioclimate chart of Xiamen and the effects of different passive
strategies in this climate. The climate of Xiamen is hot and humid, and in summer the
air humidity tends to approach saturation. In order to meet the temperature and
humidity requirements of the competition rules, air conditioning is used during the
daytime in summer. Passive strategies such as thermal mass and ventilation can be
used in the nighttime in summer, so as to reduce the energy consumption of the
building as far as possible. Based on the analysis, we used some passive strategies in
the house, such as natural ventilation and natural lighting, and two comprehensive
strategies, namely, thermal buffer space and dynamic shading.
Fig 6. Bioclimate chart of Xiamen and the effects of passive strategie
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Fig 7. Section plan of Nature Between
2.3.2 Thermal buffer space
The design strategy of a buffer space [38] is used in the inner yard located at the
main entrance of the house. The inner yard connects most of the indoor conditional
spaces of the house and serves as a thermal buffer between the indoor and outdoor
environment. It can be used to adjust the sunlight, ventilation rate and thermal
environment inside the house, thus maintaining thermal comfort and creating a good
living environment (Fig. 8). This space has two glass doors (external and internal) and
two skylights that can be opened, closed or shaded according to the weather
conditions. It can be used as a sunroom in the winter, heating the indoor air and
exchanging heat with the adjacent rooms. In summer, the skylights and the shades are
opened to promote natural ventilation and avoid overheating.
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Fig. 8. Passive design concepts of the inner yard
(a) The electric shading louvers and bamboo doors can play a role in shading and ventilation. (b) The inner yard
can be used as a thermal buffer space. (c) The skylight of the inner yard can be controlled according to the weather
conditions. (d) The indoor windows and doors can be opened on winter nights to exchange heat stored in the thermal
buffer space during the day.
2.3.3 Dynamic shading
The climate of Xiamen is hot and humid with high solar radiation intensity in the
summer, and the same was true in Dezhou during the competition. To fulfill the
indoor thermal comfort requirements in different seasons, three kinds of dynamic
shades are used that can be adjusted according to different climatic conditions.
Nature Between has a double layer roof, the upper roof stretching out at the south
loggia to provide shade for doors and windows. Electric shading louvers are used in
the roof, the angles of which can be controlled by the occupants to control direct solar
radiation based on different weather conditions (Fig. 9).
Bamboo doors are used in the south facade, forming a distinctive light and
shadow effect. They can be folded similarly to traditional Chinese style doors and are
used as a dynamic shading facade to control direct solar radiation. They can be
opened for sunshine and a better view during the winter season, and can be closed for
shading in the summer.
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Shading screens are installed on the skylight in the inner yard and the north side
windows on the second floor. When the solar radiation intensity is too high, the
electric sunshade roller curtains outside the skylight can be closed to achieve a better
shading effect, which can also be controlled easily by an intelligent control system.
Fig. 9. The gallery yard and the dynamic shading facade
2.3.4 Natural ventilation
Natural ventilation can remove heat and humidity from the house and improve
indoor thermal comfort conditions when the outdoor climate is comfortable. This is
particularly important in the climate of Xiamen and is also an important factor for
thermal comfort control.
The chimney effect is used to promote natural ventilation in Nature Between.
The height difference between the ground and upper floors, and the air temperature
difference due to the greenhouse effect in the inner yard, both help to create a
chimney effect, which can be used during the mid-season and summer days with
comfortable outdoor wind conditions.
Some windows can be controlled by the intelligent control system in Nature
Between, such as the skylight in the inner yard and the north side windows on the
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second floor. They can be controlled together with the HVAC system to regulate the
indoor thermal environment.
2.3.5 Natural lighting
The design of natural lighting is also an important issue in Nature Between.
Lighting design is based on the simulation results to guarantee a daylight level of
300lx for the main accommodation rooms. The lighting level inside the house can be
regulated through the dynamic shading systems to ensure indoor lighting comfort. The
kitchen does not have enough natural light because its windows are shaded by the
outside corridor. To compensate, a solar tube is used in the kitchen to increase natural
2.4 Active strategies
2.4.1 BIPV system
Solar panels are the only energy source in the competition, so BIPV design is
especially important for the house. Fifty-four photovoltaic panels and two solar
thermal panels for water heating are installed on the roof of Nature Between,
emphasizing the design concept of building integrated photovoltaic systems. Each PV
panel has a rated peak power of 285 Wp, so the total rated power of the solar panels is
15.39 kWp. The conversion efficiency is 17.50%. The PV panels are installed on the
south roof and are inclined to the horizontal surface at an angle of 20 degrees, which
takes into account the best orientation during the summer and can produce enough
energy to balance house energy needs during the competition.
There is a 150 mm ventilation layer between the upper PV panels and the roof,
which can take away the heat inside the layer to cool the roof surface. As the
generating efficiency of the PV panels increases when the temperature drops, this
design can also improve the efficiency of the PV system.
2.4.2 HVAC system
The HVAC system is critical in the design of zero energy buildings, because
normally its energy consumption accounts for 50% to 70% of the total power
consumption of the house, and it affects the indoor comfort and air quality directly.
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In Dezhou, the outdoor temperature varies from -15°C to +35°C and the
humidity level usually is very high in the summer. In response to the weather
conditions, two individual devices, the air conditioning system and the fresh air
system, are used in the HVAC system to control the indoor parameters independently.
Air temperature and humidity are controlled by the air conditioning system. A
reversible heat pump is used in the air conditioning system to produce heat in the
winter and cool air in the summer, with a rated cooling capacity of 8.8 kW. The fresh
air system, with an air change rate of 0.5 ach, is used to control the indoor CO2 level
to maintain healthful air indoors and to control the PM2.5 level in the house.
The HVAC system is installed and connected through the attic of the north roof.
Four fan coil units are used for the living room, the dining room and two bedrooms,
and can be controlled separately for each room. Fresh outdoor air is disposed by the
air handling unit and the air conditioning equipment and then sent into the room.
2.4.3 Control system
An intelligent control system which supports the KNX protocol is used in the
house to control the active equipment and many parts of the facade for shading and
ventilation. The aim of the automated systems is to integrate the passive systems such
as the dynamic shading, and the active systems, such as the HVAC equipment and the
electrical appliances, to reach the comfort level specified in the competition rules and
to allow the building to consume less electricity than it generates. Balancing the
building’s energy consumption and power generation is the goal of optimization.
The energy consumption of the appliances is measured and controlled through
KNX communication (Fig. 10). This protocol is open and interoperable. Specialized
equipment, such as the heat pump or the charging station for electrical vehicles,
communicates through different protocols. All the collected information is centralized
on a server for processing and used on the building. The intelligent control system
makes the house a smart home by informing the inhabitants of the operating status of
the equipment and by controlling them based on the different requirements.
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Fig. 10. Intelligent control system
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3. Energy Performance of the house
3.1. Tasks of measurement in the competition
After two and a half years of preparation, Nature Between was transported to
Dezhou in the middle of June 2018. After 20 days of intensive construction, the final
on-site tests were taken from August 2nd to August 16th. Table 2 shows the tasks in the
competition. Different tasks followed different schedules. Environmentally related
data were collected in the Comfort Zone contest for temperature, humidity, CO2 level
and PM2.5 level. Energy data were tested in the Energy Performance contest for
Energy Balance and Generating Capacity. In the Comfort Zone contest, three sensors
were provided by the committee and placed in the living room, in the south bedroom
and in the second floor bedroom. Environmental data were collected during the entire
competition, except when the public exhibit was ongoing.
During the measurements, contests and tasks were carried out simultaneously
inside the house, so the team had to prepare carefully for every task to minimize the
influence on the environmental measurement.
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Contest Contest
Contest or
Subcontest Type
Brief Description
1 Architec
Juried The architecture jury reviews and evaluates the concept, completion and innovation of the
building. In addition to the basic requirements of function and aesthetics, the competition
emphasizes the design of structure, machinery, hydropower, landscape, lighting, and innovative
use of envelope structures and materials during construction.
2 Market
Juried The jury reviews and evaluates the livability, marketability, buildability and affordability of the
building and whether the team has proposed a safe, comfortable and convenient solution for the
target group.
3 Enginee
Juried The jury will evaluate the technological innovation, functionality, efficiency and reliability
associated with the comfort of the home. While ensuring the stability of the system, the team
should consider the energy saving and market potential of the system.
4 Commu
Juried The competition requires the team to have a clear communications strategy and to promote the
design concept to the public through various means such as websites, social media and public
5 Innovati
Juried The jury investigates the team's innovative ability to solve the problems of water usage, air quality
and space heating. It also examines the team's comprehensive innovation capabilities in active and
passive solutions, and environmental, social, cultural and commercial potential.
6 Comfort
Measured Temperature (40%): Keep zone temperature in the 22°C to 25°C range
Humidity (20%): Keep zone relative humidity below 60%
CO2 Level (20%): Keep zone CO2 level below 1000 ppm
PM2.5 Level (20%): Keep zone PM2.5 level below 35 g/m3
7 Applian
Measured Refrigerator (10%): Keep refrigerator temperature in the 1°C to 4°C range
Freezer (10%): Keep freezer temperature in the -30°C to -15°C range
Clothes Washer (16%): Successfully wash eight loads of laundry (one load = six bath towels)
during contest week
Clothes Drying (32%): Return eight loads of laundry to their original weight (one load = six bath
towels) during contest week
Dishwasher (17%): Successfully wash five loads of dishes (one load = eight place settings) during
contest week
Cooking (15%): Successfully perform five cooking tasks (one task = vaporize 2 kg of water in
less than 2 hours) during contest week
8 Home
Measured Lighting (25%): All interior and exterior lights on at full level at night
Hot Water (50%): Successfully conduct 16 water draws during contest week (one water draw =
deliver 60 L of water at average 45°C temperature within 10 minutes)
Home Electronics (10%): Operate a TV and computer during specified hours
Dinner Party (10%): Host two dinner parties for up to eight guests
Movie Night (5%): Host neighbors to watch a movie on the home theater system
9 Commut
Measured Drive an electric vehicle 40 km in no more than 1 hour, four times during contest week.
At the end of the competition, the electric car needs to be fully charged.
10 Energy
Measured Energy Balance (80%): Produce at least as much electrical energy (kWh) as is consumed during
contest week
Generating Capacity (20%): The more electrical energy generated per unit PV area (kWh/m2), the
more points earned
Table 2. Tasks measured in the competition
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Fig. 15. Simulated and measured energy consumed during the competition
Heating set point
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Humidity (%) Lighting Density
Equipment load
18 26 60 3 13.2 5
Table 3. Parameter settings of the model
The monthly energy balance data are shown in Fig. 16. The cooling load of the
house is 70.0 kWh/(m2*a), much higher than the heating load, which is only 3.5
kWh/(m2*a). The influencing factors for cooling load are equipment, infiltration,
solar, mechanical ventilation and people, from large to small respectively. The
lighting load only accounts for a small proportion of the cooling load, and in winter it
is beneficial to reduce the heating load. Infiltration and mechanical ventilation (fresh
air) increase the cooling load in the summer and increases the heating load in the
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Accepted Manuscript
Fig. 16. Monthly energy balance of Nature Between in the Xiamen climate (kWh/m2)
Fig. 17 shows the simulated monthly PV power generation and the monthly
building energy consumption of Nature Between in Xiamen. Except for July and
August, the PV generation always exceeds electricity consumption. Total annual
consumption is 12544.9 kWh, which is only 75.6% of the 16590.5 kWh generated by
the PV panels. We can calculate that 11.6 kW of PV installation is enough to meet the
house’s energy balance in Xiamen.
Fig. 17. PV power generation compared to building energy consumption by month and annual simulation in
Fig. 18 compares the monthly heating and cooling loads of Nature Between in
Xiamen with and without dynamic shading. The model was set according to the actual
situation of the dynamic shading system. The shading louvers, the bamboo doors and
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Accepted Manuscript
the shading screens were controlled according to solar radiation intensity and outdoor
air temperature. The simulation results show that the annual thermal load can be
reduced by 17.4% under the condition of dynamic shading, compared with the
condition of no dynamic shading. The energy saving benefit of dynamic shading is
significant in summer, but it slightly increases the heat load in winter.
Fig.18. Thermal load comparison of Nature Between with and without dynamic shading
3.4 Lessons and recommendations
Despite the good results obtained in the competition, the experiences gained
from the measurements indicates that the design strategies of Nature Between could
be improved in several aspects:
1) Although there is good thermal insulation in the walls, windows and doors of
Nature Between, the airtightness of the walls is not good enough because of
the prefabricated construction method. The installation of some pipes, such
as the solar tube installed on the roof of the kitchen, forms thermal bridges on
the building envelope. Therefore, these parts of the building should be well
insulated to avoid heat loss and air infiltration.
2) The living room is 6 meters high and connects to the dining room and the
second floor room, resulting in a large volume and excessive air conditioning
energy consumption. If this space were divided into several small rooms and
controlled independently, then energy consumption could be reduced.
3) Because the air temperature varies greatly in Dezhou, it is better to use a
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Heating NoShading Heating dynamic shading
Cooling noshading Cooling Dynamic Shading
Accepted Manuscript
VRF (Variable refrigerant Flow) air conditioning system in the house. This
system can better adapt to the changing cooling or heating loads and achieve
better energy efficiency.
4. Conclusions
By analyzing the design concepts and energy saving technologies of Nature
Between, this paper exhibits a method of using comprehensive strategies to achieve
the goal of zero energy consumption in buildings. The practical strategies provided in
this paper could help architecture designs for residential NZEH. According to the
measured and simulation data, the following conclusions can be drawn:
1) The natural living spaces, natural materials and natural family relationship in
Nature Between embody the design concept of natural philosophy. The
measured results show that passi and active design strategies are reasonably
applied in Nature Between to achieve the balance among function, aesthetics,
comfort and energy.
2) The results shown that the Nature Between can generate more electricity than
its demand during the test in Dezhou. There was a 37.0 kWh PV generation
surplus for Nature Between during the competition in Dezhou.
3) The annual simulation results shown that Nature Between is able to achieve
NZEH in Xiamen. The simulation results show that the total annual
consumption for the house is 12544.9 kWh in Xiamen, which is only 75.6%
of the 16590.5 kWh generated by the PV panels.
We would like to express our gratitude to all the students and teachers for their
efforts to design, build, and transport Nature Between for the 2018 Solar Decathlon
China competition. We also appreciate Xiamen University and our cooperative
enterprises for giving us financial and other support. The research was also supported
by the National Natural Science Foundation of China (Grant No. 51778549) and the
Accepted Manuscript
Natural Science Foundation of Fujian Province (Grant No. 2017J01102), and the
Fundamental Research Funds for the Central Universities (Grant No. 20720180065).
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Due to the increasing energy demand for space heating and cooling, renewable energy power generation and integration of energy storage systems received attention around the world. A method to reduce energy demand of buildings is the application of thermal energy storage (TES) systems. This is due to the possibility of storing heat/cold energy to release it when required, which can tackle the temporal gap between energy demand and supply. In this work, phase change materials (PCMs) have been considered as a useful passive method. In the summer, PCMs can absorb the excessive heat during day time and release the stored heat during night time. A composite wall filled with different PCMs was developed and analysed using TRNSYS software with the purpose of integration into passive near zero building applications. The results show that the PCMs in walls can reduce building energy use on daily basis and help achieving the goals of a net zero energy building (NZEB) in future.
The conception of net zero energy buildings (NZEB) has been introduced to limit energy consumption and pollution emissions in buildings. Classification of NZEB is based on renewable energy (RE) supply options, energy measurement process, RE-sources location, and balances whether are energetic or exergetic. In general, it is traditionally agreed that there are three main steps to reach the NZEB performance, starting through the use of passive strategies, energy efficient technologies, and then RE generation systems. Then, these three steps could be accompanied with the smart integration of advanced efficient energy technologies. A state of the art shows that the main ZEB studies are related to: energy savings, reduce electric bills, energy independence, pollution reduction, and occupants comfort, in addition, others are more interested in the aesthetic aspect by combining modern technologies with innovations to achieve high energy and sustainability performance. Building optimization is a promising technique to evaluate NZEB design choices; it has been adopted to choose the perfect solution to reach the zero energy performance through the optimization of an objective function related to energy (thermal loads, RE generation, energy savings) and/or environment (CO2 emissions) and/or economy (life-cycle cost (LCC), net-present value (NPV), investment cost). This paper starts by presenting the global energetic and pollution challenges the world faces. Moreover, it shows, to the best to the author’s knowledge, the existing NZEB definitions and the corresponding case studies investigated in 8 different climatic zones (humid continental, humid subtropical, Mediterranean, moderate continental, moderate continental, marine west coast, tropical, semi-arid and hot), the paper also focus on the importance to treat each climate separately. Even in the same country, two or more climates may co-exist. NZEBs drawbacks are also presented. Furthermore, different optimization problems are reviewed in the last section. Building energy optimization methods are employed to obtain the ideal solution for specific objective functions which are either related to energy, and/or environment and/or economy. Optimization variables are distributed between passive and/or RE generation systems. Finally, a table summarizing the most commonly used electric and thermal RE applications which yield to the zero energy balance in each climate, as well as three flowcharts are presented to summarize the whole three-stage procedure, to reach NZEB, starting from building designing, passing through the optimization procedure, and lastly categorizing the zero energy balance.
This paper reports the design process and measured performance of the University at Buffalo's net-zero energy prototype, the GRoW home, designed for the 2015 Solar Decathlon in Irvine, CA. Sustainable design intentions and pragmatic constraints are discussed in addition to the energy considerations for each design element. The GRoW home includes features designed to support a unique lifestyle, including an integrated greenhouse (the “GRoWlarium”) and various operable systems under the occupant's control. Whole-building energy simulations, spreadsheet calculations, daylighting simulations, and proprietary sizing software were used in design decision making. Energy performance predictions and measured results from the 2015 competition are discussed. The home was predicted to consume 177.11 kWh, and produce 238 kWh during the competition; it actually consumed 161 kWh, and produced 191 kWh, an error of 3% and 8%, respectively. The GRoW home ultimately had the lowest energy consumption of any SD 2015 house which successfully performed all competition-required tasks.
West Virginia University and University of Rome Tor Vergata have partnered for the Solar Decathlon 2015 to present STILE (Sustainable Technologies Integrated in a Learning Experience), a house that merges Italian and Appalachian design concepts with innovative energy techniques. The aim of the work is the construction of a reliable and accurate dynamic building simulation model to perform a posteriori critical analysis of energy performance of the STILE house during the competition and to investigate the capability of the same house during a typical year in different locations. This was possible through the calibration of a dynamic simulation model of the house, using data gathered during the contest in Irvine, USA in October 2015. The work helped us to better understand the problems faced and to find optimized solutions that did not alter the original architectural concept. A 17% saving in the HVAC energy consumption for the period of competition was obtained by acting on shading, windows materials, and adequate floor insulation. The same model was also used to evaluate STILE behavior in different climatic conditions for a typical year. The study shows that the house has satisfactory thermal performance with mild and temperate climates, or whenever a benefit can be obtained by the use of the solar chimney.
The relationship between indoor comfort and climatic context is essential to assure a superior liveable environment for occupants. The international approach called Active House (AH) proposes a ranking system to evaluate the provided indoor comfort, which is the same through the whole Europe, without acknowledging the variety of social-cultural contexts of each country. This paper aims to understand whether the AH methodology can be proposed both for continental and Mediterranean climates, evaluating the indoor comfort performances of a single-family home in four different climatic conditions, representative of different climate severities. The RhOME for denCity building, the winning prototype of the international competition Solar Decathlon 2014, has been used as experimental case study. From the results a variation of the AH comfort thresholds is proposed to fulfil the cultural and social environment of warm regions, considering the acclimatization process which arise the boundary of comfort acceptability. The proposed new comfort threshold still provide high thermal comfort expectation with an energy saving estimation of about 1.7% for each half degree Celsius reduction.