Developing a Home According to the Solar Decathlon Competition Considering Cuiabá
Climate
Desenvolvimento de uma Edificação de Acordo com a Competição Solar Decathlon
Considerando o Clima de Cuiabá
Ursula Maira Maciel Rigon 1, André Luiz Nonato Ferraz 2
Abstract: The residential sector consumes about a quarter of all electricity generated in the world and has become a major contributor to the increase in energy demand in recent years. Because of that, many countries began to concern the energy efficient way of build. The Solar Decathlon created by the United States is a competition that encourages students around the world to build energy efficient and affordable homes with attractive design. This article aimed to develop and analyze a home project according to the competition’s rules and requirements considering the hot climate of Cuiabá – Brazil. For that, it was used the Solar Decathlon Rules manual to guide the strategies and the design parameters. The house optimization was made by simulating highlight strategies such as: passive strategies, high thermal performance materials, efficient air conditioner and lighting systems, and automation advantage. In the simulations it was used the DesignBuilder software – EnergyPlus. Further, it was discussed topics proposed by the competition, such as: commuting, smart water use and reuse, and energy production by renewable sources. In the end, each context of the competition received a score and was evaluated individually. As conclusion, it was observed that the house designed had sufficient energy generation to satisfy the user’s profile established and the electric car being, in this case, a net zero-energy balance. However, it was observed the non-satisfactory market potential of the house and the reasons of such result was also discussed. Keywords: Energy Efficiency; Market Potential; Net Zero Energy Balance; DesignBuilder.
Resumo: O setor residencial consome aproximadamente um quarto de toda energia elétrica gerada no mundo e se tornou um dos grandes responsáveis pelo aumento da demanda energética nos últimos anos. Por isso, muitos países começaram a se preocupar com construções que sejam eficientes energeticamente. O Solar Decathlon, desenvolvido pelos Estados Unidos, é uma competição que incentiva estudantes ao redor do mundo a construírem casas eficientes, com custo acessível e design atraente. Este artigo teve como objetivo desenvolver e analisar o projeto de uma edificação de acordo com as regras e requisitos da competição para o clima quente da cidade de Cuiabá - Brasil. Para isso, como metodologia, foi utilizado o manual de regras da competição Solar Decathlon para determinar estratégias e parâmetros de projeto. A otimização da casa foi realizada através de simulação com destaque para as seguintes estratégias: estratégias passivas, materiais de alto desempenho térmico, ar condicionado e iluminação eficientes, e benefícios da automação. Para as simulações foi utilizado o software DesignBuilder - EnergyPlus. Além disso, foram discutidos tópicos propostos na competição como: uso de veículos elétricos para transporte, uso e reutilização inteligente da água, e produção de energia local por fontes renováveis. Ao final, cada tópico da competição recebeu uma nota e foi analisado de forma individual. Como conclusão, observou-se que a casa projetada possui geração de energia suficiente para satisfazer o perfil dos usuários estabelecido e o deslocamento por carro elétrico sendo, neste caso, uma edificação de zero balanço energético. Entretanto, foi observado que o potencial de mercado da casa não foi satisfatório e as razões desse resultado foram também discutidas.
Palavras-chave: Eficiência Energética; Potencial de Mercado; Zero Balanço de Energia; DesignBuilder.
1 Introduction
The obsolete way of construction, which is nowadays outdated and inadequate, has been resulting in a growth of energy demand. Therefore, instead of reducing energy consumption, households spend more energy each year. Two facts can explain this growth; one is due to the electricity access for new house-holds, and the other is due to the home equipment and technologies, and to the users’ behavior (KOS; SOUZA, 2014). Because of that, many countries have been developing new buildings regulations, actions and plans to encourage the construction of energy efficient buildings.
The Solar Decathlon competition is one of the United States Department of Energy efforts to achieve the reduction of residential energy consumption, because it (1) Educates academic students and the public about environmental benefits and design solutions presented
by clean-energy products, and also, demonstrated the money-saving opportunities from it; (2) Exhibits that energy efficient homes with renewable energy system can present comfortable spaces and affordable projects; (3) Prepares students and professionals with unique knowledge to enter the nation’s clean-energy workforce (KOS; SOUZA, 2014).
2 Literature Review
2.1 The Solar Decathlon Competition
The Solar Decathlon scores the houses in a 10 separately contests, and each contest worth up to 100 points (ENERGY, 2016). The contests are:
a) Architecture: It is evaluated by a jury of architects that will assign an overall score considering the concept and design approach, the architectural implementation and innovation, the documentation and presentation of the house.
b) Market Potential: It is evaluated by professionals from the homebuilding industry. The criteria for this contest is the cost effective and the buildability of the house.
1Civil Engineering Undergraduate Student, Mato Grosso State
University, Sinop - MT, Brazil, [email protected]
2Prof. Dr. André Luiz Nonato Ferraz, Mato Grosso State University,
c) Engineering: It is evaluated by a jury of engineers. The criteria will consider the approach, design, efficiency, performance and documentation of the house.
d) Communications: A jury of communications professionals will score considering strategy, implementation and on-site communications of the teams by the materials and efforts to educate, inform and interest the public.
e) Innovation: A jury of industry professionals will consider research, sustainability and innovation criteria to score.
f) Water: It is evaluated by industry professionals that will analyze smart conservation, reclamation and reuse.
g) Health and Comfort: This contest scores the interior comfort conditions suitable for inhabitants by the measuring of temperature, illuminance, humidity, and air tightness.
h) Appliances: It is evaluated based on the functionality and efficiency of the home appliances and equipment.
i) Home Life: This contest evaluates the success in host two dinners party and in host a game night. Also, it evaluates the commuting concept application.
j) Energy: This contest evaluates the energy balance of the house through the comparison between the energy production and the energy consumption. 2.2 Main Strategies
To design a Net-Zero Energy Balance (NZEB), it is primordial to optimize the main systems and elements of the home applying energy efficient strategies. The state-of-art is discussed based on authors references in the following aspects:
a) The envelope is considered to be the skin of a building (YUN et al., 2010). It is the main source for the thermal loads and for daylighting (PEDRINI et al., 2002). To optimize a high-performance facade, the passive strategies are the most suitable method, because it increases the energy efficiency and contributes to the interior thermal comfort and lighting conditions (RODRIGUEZ-UBINAS et al., 2014).
b) The Photovoltaic (PV) technique is known as the best method to convert solar energy into electricity without any help from heat engines (ZHOU et al., 2016). For the Solar Decathlon scenario, the sunlight is the main renewable energy source converted in electric energy by the PV panels. c) Domestic Hot Water (DHW) is the main aspect in
terms of thermal energy needed in a NZEB (MOLDOVAN et al., 2014). The Solar Water Heater (SWH) is widely used in households because the solar energy is a clean energy, and it is the richest inexhaustible source between all kinds of renewable energy resources; furthermore it has low cost and easy installation (ZHOU et al., 2016). d) The HVAC consumes the largest amount of energy use in a residential building (HOMOD et al., 2014). Common efficient systems available in the market are the gas-boilers and the mini-split air conditioners (ADHIKARI et al., 2012). However,
many authors designed their own HVAC system according to the house peculiarities. In this case, it is considered the house compositions (HOMOD; SAHARI, 2013).
e) The lighting is responsible for approximately 15% of energy consumption in residential buildings. Reducing energy use for lighting in a house can be achieved by using low consumption luminaries, daylight integration and light control sensor or presence sensor (CHOI et al., 2016).
f) The appliances and the electronics are the third system in energy use in a home (INVIDIATA; MIZGIER, 2013). The appliances and electronics used in a NZEB are the high energy star rated equipment (BERRY et al., 2014).
g) The Electric Vehicle (EV) for transport in a house can benefits energy security, global and local environment, and economic growth. For the commuting implementation, it should considerate the household daily activity-travel schedules or daily mileage, and the EV charges demand, concerning the best EV for the household necessities (DAINA et al., 2017).
2.3 Climate of Cuiaba
The city of Cuiaba capital of Mato Grosso State has a tropical climate. The average annual temperature is about 26.8 °C, with maximum average of 42° C and minimum average of 15 °C (INMET, 2017).
3 Methodology
To develop the home design, it was elaborated each competition’s topic in the following order to optimize the house in a maximum way. The methodology sequence is shown in Figure 1.
Figure 1: Methodology’s Stages. Source: Authors, 2017.
3.1 Architectural
According to Matallanas et al. (2014), in this contest, the interest is the attractive design, which it should combine comfortable and functional spaces, bioclimatic technologies and passive strategies of energy efficiency, and also, a coherent and comprehensive design. The AutoCAD was the software used in this step.
3.2 DesignBuilder Simulation
The following six contests were elaborated and analyzed through the simulation in the DesignBuilder software. Stages Architectural DesignBuilder Simulation Home Life Appliances Health and Comfort Engineering Innovation Energy Water Market Potential Home Final Score
3.2.1 Home Life
Following the authors Invidiata & Mizgier (2013) and considering that in this work the house is a research project only, this contest aimed to elaborate a weekly schedule of the house usage for lighting, and occupation. The schedule was elaborated based on the Technical Quality Regulation for the Energy Efficiency Level of Residential Buildings (RTQ-R 2.2) (BRASIL, 2012).
The occupation schedule considered two people by room when it is occupied. It was also considered, a different house usage between weekdays and weekends/holidays. Furthermore, it was set up different metabolic rates in accordance with the ambient: living room (60 W/m²), home office (60 W/m²), bedroom (45 W/m²) and kitchen (115 W/m²) (BRASIL, 2012). The final schedule is shown in Table 1.
Table 1: Occupancy Schedule
Weekdays Weekends/Holidays Time/Occupancy Time/Occupancy Bedroom 0:00 - 07:00 100% 07:00 - 20:00 0% 20:00 - 21:00 50% 21:00 - 24:00 100% 0:00 - 09:00 100% 09:00 - 10:00 50% 10:00 - 20:00 0% 20:00 - 21:00 50% 21:00 - 24:00 100% Living Room 0:00 - 13:00 0% 13:00 - 18:00 25% 18:00 - 19:00 100% 19:00 - 21:00 50% 21:00 - 24:00 0% 0:00 - 10:00 0% 10:00 - 11:00 25% 11:00 - 12:00 75% 12:00 - 13:00 0% 13:00 - 14:00 75% 14:00 - 17:00 50% 17:00 - 19:00 25% 19:00 - 21:00 50% 21:00 - 24:00 0% Kitchen 0:00 - 07:00 0% 07:00 - 8:00 100% 08:00 - 11:00 0% 11:00 - 13:00 100% 13:00 - 18:00 0% 18:00 - 20:00 100% 20:00 - 24:00 0% 0:00 - 07:00 0% 07:00 - 8:00 100% 08:00 - 12:00 0% 12:00 - 14:00 100% 14: 00 - 18:00 0% 18:00 - 20:00 100% 20:00 - 24:00 0% Home Office Until: 08:00 0% Until: 09:00 100% Until: 24:00 0% 0:00 - 24:00 0% Source: Brasil, 2012.
The lighting schedule was elaborated in the same way based on the RTQ-R 2.2. It also considerates different usage for weekdays and weekend/holidays. The final lighting schedule is shown in Table 2.
Table 2: Lighting Schedule
Weekdays Weekends/Holidays Time/Occupancy Time/Occupancy Bedroom 0:00 - 06:00 0% 06:00 - 07:00 100% 07:00 - 20:00 0% 20:00 - 22:00 100% 22:00 - 24:00 0% 0:00 - 08:00 0% 08:00 - 09:00 100% 09:00 - 20:00 0% 20:00 - 22:00 100% 22:00 - 24:00 0% Livingroom 0:00 - 16:00 0% 16:00 - 21:00 100% 21:00 - 24:00 0% 0:00 - 10:00 0% 10:00 - 12:00 100% 12:00 - 16:00 0% 16:00 - 21:00 100% 21:00 - 24:00 0% Kitchen 0:00 - 07:00 0% 07:00 - 8:00 100% 08:00 - 18:00 0% 0:00 - 07:00 0% 07:00 - 8:00 100% 08:00 - 18:00 0% 18:00 - 20:00 100% 20:00 - 24:00 0% 18:00 - 20:00 100% 20:00 - 24:00 0% Home Office 0:00 - 08:00 0% 08:00 - 09:00 100% 09:00 - 24:00 0% 0:00 - 24:00 0% Source: Brasil, 2012.
For the commuting topic, according to Daina et al. (2017), it was defined the EV usage in kilometers based on the house user’s profile established. The user’s profile was defined considering the Energy (2016) parameter which is 25 miles (40Km) per week day. 3.2.2 Appliances
According to Berry et al. (2014) all the appliances used in the house were set as a high energy star rated equipment. The low devices consumption were set up in the DesignBuilder software. In the same way of the home life, it was elaborated a schematic schedule according to Invidiata & Mizgier (2013), in order to calculate the energy consumption of the devices. The appliances schedules are shown in Table 3.
Table 3: Appliances Schedules
Appliances Power (W) Hours of Usage
per Day TV 92 3 Laptop 95 2 Cooktop 1000 1.5 Refrigerator 67 24 Oven 3500 0.5 Dishwasher 1050 0.25 Blender 400 0.25 Microwave 2000 0.25 Clothes Washer 1220 0.5 Hair Dryer 2000 0.25
Source: Invidiata & Mizgier, 2013.
3.2.3 Health and Comfort
For the health and comfort contest it was set up values in the DesignBuilder that provide interior comfort conditions suitable for inhabitants. According to the Energy (2016), the humidity value was set up between 35-60%, target illuminance of 300 lux, and airtightness of 0.7 Air Change per Hour (ac/h). The air temperature value used was based on the RTQ-R 2.2, that provides 24°C as a comfort temperature for the Brazil climate. 3.2.4 Engineering
According to the Energy (2016), this contest aimed to achieve the best house’s efficiency and performance. For that, it was simulated in the DesignBuilder a mix of different construction materials for the building envelope. For the system modeling, it was created a base case, with standard techniques as point of reference (fluorescent lamp, and Split C) to compare the total energy consumption of the house and the cost benefits of the lighting and HVAC systems tested. a) Construction Materials
The materials simulated for walls, roofs and floors layers were: Gypsum Board (GB), Structural Insulated Panels walls (SIP walls), composed by Oriented Standard Board (OSB) - wood based, Fiber Reinforced Cement (FRC), and Expanded Polystyrene (EPS) as insulated material. According to Kamel & Memari (2014), those components were the most used in the Solar Decathlon competition last’s years. The glazing types simulated were: single clear 3mm, habitat
champanhe, sunguard neutral 14, and sunguard neutral plus 50.
b) HVAC System
For the HVAC system, it was considerate the house compositions, according to Homod & Sahari (2013). The systems chosen to be simulated in the DesignBuilder, that were highly used in the Solar Decathlon were: Split A, Split Super Inverter and Variant Refrigerant Flow (VRF). The base case used was the Split C. To take the final choice it was considered the energy consumption and the cost benefits of each system.
c) Lighting System
For the lighting system were considered only the Light-Emitting Diodes (LED) lamps with different luminous efficiency for simulation. It was decided based on the authors Choi et al. (2016), who cited the LED luminaries as state-of-the-art, due to its low energy consumption and its low heat emission.
d) Hot Water System
According to Zhou et al. (2016), the SWH is the best option for the residential hot water delivery. It was the only technique analyzed in this work. The solar collectors were simulated by the UNISOL website considering the input information as: hot climate, 2 users, and only bathroom for hot water consumption. e) Photovoltaic System
Following Zhou et al. (2016), whom considered the PV system the best technique to generate renewable electricity, the PV panels were the only option analyzed. The PV system was simulated in the Portal Solar website. It was used as input information: the city and state; and the monthly energy consumption of 398.73 kWh calculated in the DesignBuilder based in previous configurations.
3.2.5 Innovation
The innovation contest was applied into the automation concept. According to Irulegi et al. (2014), the automation provides a greater comfort and convenience, and also provides energy economy. It was modeled and tested in the DesignBuilder software different automation systems in order to improve the thermal comfort and the energy consumption of the house.
3.2.6 Energy
According to Energy (2016), the energy contest analyzes the balance energy between the energy produced by the renewable source installed in the house and the total energy consumed by it. The energy balance would be satisfactory if it is equal zero, in other words, if the same amount of energy produced is equal to the energy consumed. The analysis of the energy
balance was made by the DesignBuilder simulation, where it was possible to calculate both values of production and consumption.
3.3 Water
This contest aimed to present a smart use, reclamation and reuse of the water, according to Energy (2016). Following Lamberts et al. (2010), it was designed a graywater system by the Hydros V.4 software, and applied techniques of smart conservation.
The Hydros V4 is a software from the AltoQi package that permits to design the water plan of a building. It is possible to draw the whole water system, from the water tank to the points of use, also, it allows to dimension the pipes and to verify the pressure. 3.4 Market Potential
According to Energy (2016), the market potential contest goal is to evaluate the cost benefits and the buildability of the entire house. To make this analysis, it was budgeted the house’s components and systems by the National System of Research of Costs and Indices of the Civil Construction (SINAPI) website. Then, it was compared the final cost with a standard house in Brazil according to the Basic Unit Cost (CUB) website. The comparison allowed to classify the market potential of the house.
The SINAPI was created by the Brazil Federal Savings Bank (CEF). It aims to budget projects and to monitor indices, costs and prices of the civil construction (BRASIL, 2017). The CUB was created by the Brazilian Chamber of Construction Industry (CBIC).It considers the cost per square meter of construction of a standard project, calculated according to the methodology established by the Civil Construction Industry Unions (SINDUSCON, 2017).
3.5 Home Final Score
Finally, according to the Energy (2016), it was calculated a home final score with goal to get an overall evaluation and analysis of the entire house.
4 Results 4.1 Architectural
The house designed was a one floor 72 m². The floor plan shows up comfortable and functional spaces for a family living. The layout keeps in mind clean space concept, which results is a minimum volume of walls to transport and assembly. Additionally, it was applied energy efficiency strategies, such as: sleeping area east oriented and living areas north oriented; doors and windows in an appropriate ratio and location to generate cross ventilation and daylight integration. The floor plan designed in the AutoCAD software is shown in Figure 2.
Figure 2: Floor Plan. Source: Authors, 2017.
4.2 DesignBuilder Simulation 4.2.1 Home Life
For the commuting, it was verified at the Solar Decathlon website that the electric cars most used in the last competitions were BMW I3 and Nissan Leaf (Energy, 2017). Analyzing both cars consumption, it was decided to use the Nissan Leaf to simulate the car energy consumption because it is a more efficient vehicle. The car energy consumption is about 30kWh/100miles (160km). It was estimated a user profile of 135kWh/450miles (720km) per month. 4.2.2 Appliances
It was verified at the DesignBuilder software that the high energy star rated equipment has a lower consumption of 30% when compared to common equipment. The rooms with the appliances and the energy consumption calculated at the DesignBuilder is shown in Table 4.
Table 4: Appliances and Equipment’s Annual Energy Consumption by Room
Rooms Annual Energy
Consumption (kWh) Kitchen 1,110.37 Living Room 99.36 Bedroom - Bath 72.32 Laundry 218.42 Home Office 49.12 Source: Authors, 2017.
Using high energy star rated equipment provided a total energy annual economy of 825.55 kWh being about 10% in the house’s energy consumption amount. 4.2.3 Health and Comfort
It was verified at the DesignBuilder simulation that the input values for this contest was obeyed among the entire year. The humidity average was 57%, the target illuminance was 300 lux, the air tightness kept the value of 0.7 ac/h and the air temperature was 24°C while the local was occupied.
4.2.4 Engineering a) Construction Materials
In view of materials with great thermal properties (out/inside insulation, low transmittance), it was calculated the thermal transmittance and thermal capacity properties of them. The properties values are shown in Table 5.
Table 5: Walls Material’s Thermal Transmittance (U) and Thermal Capacity (CT)
Material (W/m²K) U (kJ/m²K) CT
GB + EPS + GB
(1.25+6.5+1.25) cm 0.53 24.23
OSB + EPS + OSB
(1.25+6.5+1.25) cm 0.51 34.85
GB + OSB + EPS + OSB + GB
(1.25+0.95+6.5+0.95+1.25) cm 0.50 48.26
Source: Authors, 2017
Considering the values above, it was decided to use the system of GB + OSB + EPS + OSB + GB for the walls, because it has the best thermal properties comparing to the others.
For the roofing system, it was decided to use thermoacoustic tile and GB lining, due to its thermal and acoustic properties, and, high application on home constructions.
For the flooring system, it was used the FRC 2.5cm, because of its buildability advantage to assembly and transport. This system was not set up using insulated material because it was wanted the ground heat exchange as an improvement for thermal comfort. For the glazing system, it was decided to use the single clear 3mm with external solar shading as passive strategy, because it has the best cost benefit choice. The application of the materials above generated a total annual energy economy of 896.12 kWh being about 10% in the house’s energy consumption amount.
b) HVAC System
The HVAC properties, annual energy consumption – based on the occupation schedule; annual energy cost and simple payback from the different systems tested are shown in Table 6.
Table 6: Total Electricity Consumption of the House with Different HVAC Systems
System CoP KWh (annual) R$ (annual) Payback (years) Base Case (Split C) 2.8 7,531.41 5,648.56 - Split A 3.2 7,066.50 5,299.88 3.4 Split Super Inverter 3.8 6,552.65 4,914.49 8.2 VRF 4.1 6,352.13 4,764.10 13.6 Source: Authors, 2017.
Considering the payback, the HVAC choice would be the Split A. However, it was decided to use the Split Super Inverter, due to two considerations: air conditioner’s lifetime as 10 years, and photovoltaic cost that each system would generated. The air conditioner Split Super Inverter had a total economy of R$4,796.70 versus the Split A economy of R$3,906.83.
The Split Super Inverter provided a total annual energy economy of 1,179.28 kWh being about 15% in the house’s energy consumption amount.
c) Lighting
The LED’s luminous efficiency, annual energy consumption, annual energy cost, and simple payback are shown in Table 7.
Table 7: Total Electricity Consumption of the House with Different LED Lamps
System KWh (annual) R$ (annual) Payback (years) Base Case (Fluorescent) 7,531.41 5,648.56 - LED 80 lm/W 7,361.61 5,521.21 3.5 LED 100 lm/W 7,302.19 5,476.64 1.5 LED 120 lm/W 7,262.56 5,446.92 1.4 Source: Authors, 2017.
The lamps chosen to be used in the house was the LED 120 lm/W, because it had the best economy when comparing to the others. In addition, considering the simple payback, the LED 120 lm/W also provided the best cost benefit between the three lamps.
The LED 120 lm/W produced a total annual energy economy of 276.78 kWh being about 4% in the house’s energy consumption amount.
d) Hot Water System
The hot water delivery system modeled to satisfy the users profile has SWH of 4.5 m² with 25° north inclination - local’s latitude + 10°, and storage tank’s capacity of 300L.
The SWH system provided a total annual energy economy of 1,228.29 kWh being about 15% in the house’s energy consumption amount. The hot and cold water’s system are shown in Figure 3.
Figure 3: Hot and Cold Water’s System. Source: Authors, 2017.
e) Photovoltaic System
The PV system modeled to satisfy the house demand has 12 solar panels 245W (2,9kWp) with dimensions of 1.64x0.99m and 15° north inclination - Cuiaba’s latitude. The panels were configured as 15% of efficiency. The system provides in average around 398.75 kWh per month. The panels placed at the house’s flat roof are shown in Figure 4.
Figure 4: Photovoltaic Panels. Source: Authors, 2017.
4.2.5 Innovation
For the innovation, it was decided to use three systems: 1. Daylight Integration;
2. Automatic External Shading based on solar radiation;
3. Automatic System for Closing and Opening Windows based on internal and external temperatures.
The light sensor located at the center of each room turns off the lamps when there has enough external daylight inside the house, or no occupation. On the other hand, the system turns the lamps on when there is occupation in the room and the target illuminance is not fully provided by external daylight.
The automatic external shading provides high thermal performance by blocking the sun rays, and also, it provides daylight integration by allowing the natural daylight gets inside the house.
The automatic system for closing and opening windows consists in close the windows when the exterior temperatures is higher than the interior temperatures or when the air conditioner is turned on. On the other hand, when the exterior temperature is lower than the interior one the windows are opened to lose heat.
These systems applied in this contest provides a total annual energy economy of 337.13 kWh being about 4% in the house’s energy consumption amount. They also improved the comfort and creates a certain convenience to the users.
4.2.6 Energy
After modeled the entire house the energy consumption calculated in the DesignBuilder was 3,164.71kWh plus the 1,620.00 kWh of commuting’s energy consumption, which results in a total of 4,784.71 kWh. In total, it was reduced the energy consumption by 58% with all strategies applied. The photovoltaic system modeled generates an energy amount of 4,785.00 kWh. So, it can be concluded that the house has a net zero-energy balance.
4.3 Water
The smart use of the water was applied using water’s saving devices such as: aerators for sink faucets, dual flush toilet discharge, shower’s register flow controller, and garden hose sprayer.
The smart reclamation and reuse were applied into the graywater system. The process consists of shower, washbasin and laundry water’s capitation to a root zone tank for water treatment, then the water is stored in a tank being available to the toilet flush and for the garden. The graywater system is shown in Figure 5.
Figure 5: Graywater System. Source: Authors, 2017.
The application of such systems provided a total water use economy of 50%.
4.4 Market Potential
The difference between the standard price and the Solar Decathlon house price is shown in Table 8.
Table 8: Home’s Cost
Material Base System (R$) Solar Decathlon House System (R$) Walls 88.00/m² 120.00/m² Tile 20.00/m² 45.00/m² Line 19.00/m² 45.00/m² Floor 73.00/m² 130.00/m² Photovoltaic System with 12 Panels - 22,536.00 HVAC 4,000.00 10,000.00 Lighting 114.00 393.00
Hot Water System - 6,589.00
Graywater System - 1,200.00
Automation Systems - 17,304.00
Total m² Value 1,418.27 2,361.75
Source: Brasil, 2017; SINDUSCON, 2017.
Comparing to a standard house of 72m² in Brazil, the final cost would be R$ 102,115.44 to a standard low R-1B category (SINDUSCON, 2017). The Solar Decathlon house on the other hand, would cost R$ 170,046.20, being more expensive in 66% than the standard home. So, the market potential can be evaluated as non-satisfactory when comparing to the standard price. However, it is important to keep in mind the benefits of the entire home’s system to the environment, since they are all from renewable and inexhaustible sources. In addition, when calculated the simple payback the house would be paid in 20.7 years. Considering the lifetime as 50 years the house would generate an energy economy of R$ 95,820.49 (127,944.30 kWh) during its life cycle.
4.5 Home Final Score
Lastly, it was evaluated the home score considering the Energy (2016) requirements and the house’s performance. The technical contests earned 100 points if they obeyed all the competition’s requirements, if not it was applied reduced points. The jury contests earned an illustrative points in order to calculate the final score. The final home’s score up to 900 points once the contest communications was not elaborated in this work. The final home’s score is shown in Table 9.
Table 9: Home Final Score
Contest Decathlon’s
Requirements Home Results Score
Architecture Architectural concept, design approach, implementation and innovation Coherent and comprehensive project with comfortable and functional spaces, and with passive strategies application 80 Home Life Show the livability of the house Schedules for: Occupancy/ Air conditioner Lighting Appliances Commuting 100 Appliances Functionality and efficiency of the home appliances All appliances were configurated as high energy star
rated equipment, with 30% of lower energy consumption 100
Health and Comfort Interior comfort conditions of temperature, illuminance, humidity and air tightness Temperature of 24°C; Illuminance of 300 lux; Humidity of 57% Air Tightness of 0.7 ac/h 100 Engineering Satisfactory design, efficiency, and performance of the house systems and materials Thermoacoustic materials SWH system
for hot water Split Super Inverter system for air conditioner LED luminaries for lighting Photovoltaic System for energy generation 100 Energy Net zero energy balance Energy Produced ≥ Energy Consumed 100 Water Smart use, reclamation and reuse Water’s Saving Devices, and Graywater System 100 Innovation Sustainability Light Sensor External Shading Openings Automatic Close and Open System 80 Market Potential Cost benefit and buildability Payback of 20.7 years and total economy of R$ 95,820.49 70 Final Score 830 Source: Authors, 2017. 5 Conclusions
The goal of this article was to design a self-sufficient house considering the Solar Decathlon rules, that combines affordable price with attractive design. For that, the following conclusion can be reached:
• The house presented a self-sufficient energy and hot water production for the user’s profile established. The strategy in this work was not only to dimension the photovoltaic and solar collector system for any house; but it was mainly first optimizing the entire house performance by a variety of strategies applied, such as: passive strategies into the house design, high energy star rated equipment, high thermoacoustic material’s performance, efficient HVAC and lighting system, automation advantage, and the use of renewable and inexhaustible sources of energy and hot water production. Further, it was applied water’s smart use, reclamation and reuse, by the water’s saving devices and by the graywater system; commuting concept. • The market potential for the house presented in this work was considerate as
non-satisfactory due to the difference of R$ 67,930.76 (66%) when compared to a standard house. However, the energy economy can compensate the whole investment in 20.7 years. It is believed that this non-satisfactory result can be improved as the industries and builders start to think sustainably; as consequence, it would have an encouragement for that type of construction making the costs more affordable;
• The attractive design element in this work worried about to show the possible livability of the house by the schedules created for occupancy, lighting, appliances and commuting. In addition, the floor plant created could show up comfortable and functional spaces for any family living.
The home final score which had a good evaluation, demonstrated that the house modeled in this work highly followed the rules and requirements of the Solar Decathlon Competition. Besides, this work has a high potential to educate academic student and encourage professionals about the benefits of the sustainable way of construction.
Acknowledgements
I am extremely grateful to my wonderful mom and grandmother for all cheerfulness and emotional support, and to my keeper daddy for all financial and intellectual support in this college lifetime.
I am highly thankful to the awesome man Marlon Leão for all knowledge, patience and complicity.
I am thankful to my professor Andre Luiz Nonato Ferraz for all help and friendship.
Last but not least, I am very grateful to my friends Ariany Cardoso, Vanessa Gatto, Camila Kloster, Juliane Ancel, Phamela Parente and Mauri Antunes for the sharing of experiences and learning, and for the vast laudable histories lived together.
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