The U.S. Department of Energy Solar Decathlon is a biannual competition that challenges 20 collegiate teams to design, build, and operate solar-powered houses that are cost-effective, energy-efficient, and attractive. The winner of the competition is the team that best blends affordability, consumer appeal, and design excellence with optimal energy production and maximum efficiency.
The University of Hawaii, dubbed as TeamHawaii, was selected to be a competitor for the 2011 Solar Decathlon. TeamHawaii's mission is to create a sustainable and affordable housing solution that is adaptable to varied cultures and climates with an emphasis on Hawaii and tropical climates.
As a software designer and developer for the solar decathlon house, my first task was to define the requirements for the home management software system. I did this by creating user stories that encompassed the most essential management functions in the solar decathlon house. User stories define the role of the person interacting with the system, the goal(s) of the interaction, and the benefits that would accrue from the interaction. I created 10 user stories below:
As a home occupant, I would like to know the current levels of energy generation, expenditure, and storage. Based on these metrics, the system will approximate the available energy budget and energy usage for the day. If energy consumption is estimated to be greater than the budget, the system will alert me and offer suggestions to reduce power usage. Thus, I will be able to achieve a net energy consumption of as close to zero for the day.
As a home occupant, I would like to know how long it would take to heat a given volume of water to 110°F, and how much hot water has been used for the day. The water heating system will alert me if hot water usage is substantially higher than what I normally use, which may indicate a running faucet or leak. Thus, I will be aware of my daily hot water usage and its impact on total energy expenditure.
As a home occupant, I would like to have a lighting system that will respond to voice commands or a touchscreen interface. There will be multiple voice commands, one being able to turn on lights in the immediate vicinity around each occupant. Thus, voice-activated lights will provide convenience and save energy by turning off unneeded lighting.
As a home occupant, I would like to know and be able to control the current temperature and humidity in each room. If I do not specify a temperature and humidity, the air conditioning system will default to a temperature within 71°F to 76°F and a relative humidity below 60% when there is an occupant in the home. Thus, the AC system will maintain a comfortable environment to live in.
As a home occupant, I would like to have a security system that will allow entry to the home through face, fingerprint, or voice recognition. A database will maintain a modifiable list of people who may enter the home at certain times of the day. For example, immediate family members will be allowed entry 24 hours a day, while friends will be allowed entry only during a time that I have specified. Thus, I will never be locked out of my home and expected visitors will not be inconvenienced.
As a home occupant, I would like to have a surveillance system that activates only when someone enters the surrounding premises of the house. If an unidentified person loiters around the home for more than 20 seconds, the security system will alert me on my phone or computer and offer a live video feed. Thus, I will be able to respond remotely to security situations and secure my home from intruders.
As a home occupant, I would like to know the current levels of oxygen and carbon dioxide in the aquaponics ecosystem. The system will alert me if gas levels become unbalanced, and will offer suggestions to correct the problem. Thus, I will be able to address any issues before they get out of hand.
As a home occupant, I would like to know the current refrigerator, freezer, and dishwasher temperature. In addition, I would like to know how long it would take to wash a given load of laundry. The refrigerator will maintain a temperature within 34°F to 40°F. The freezer will maintain a temperature within -20°F to 5°F. The dishwasher will reach a temperature of at least 120°F during a wash cycle. If any of these conditions fail, the system will alert me and indicate which has failed. Thus, I will be able to ensure the safety of my food and assess the condition of my home appliances.
As a home occupant, I would like to control my home entertainment systems through an interface on a single device. I will be able to adjust various settings for the lights, television, speakers, and computer(s). Thus, I will be able to enjoy the convenience of entertaining myself and my guests without having to get up.
General User and Repair
As a home occupant and repairman, I would like to have access to all metrics and status information for each system in the house. In addition, any problems that arise will generate an error report containing the date, time, location, and a snapshot of current conditions. These will be viewable through an interface on a single device. Thus, I will be able to quickly troubleshoot and repair any hardware problems.