June 19, 2018
|By: Christine Young
Blogger, Maxim Integrated
Over the next couple of years, a house like no other will rise in the Central Savannah River Area of South Carolina. This proof-of-concept home is a dream house of sorts, as it promises to be stingy with energy usage, require no maintenance for 40 years, and anticipate and meet the needs of its occupants and itself.
It was all inspired by an LED light bulb.
Martin Winston, editor of the Newstips Bulletin for journalists, has embarked on a multi-year project to create the proof of concept home. He notes that observing how much his electric bill dropped when switching to long-lasting LED bulbs led him to ponder what else could be done to lower energy costs and minimize maintenance tasks. An autonomous house came to mind, one that would be:
"If I have an aspiration for this project house, it's inspiration for others – builders or the people who engage them to build new homes – to go beyond what’s normal and consider what could be better. I know this house represents more than the usual costs upfront between the automation expenses, the better and smarter materials chosen for the build, and the extra labor those involve…but at the end of the day, the daily cost of operations drops dramatically, and over the course of decades, the total cost of ownership is far less than the usual ways of building homes."
Winston is about 2.5 years into the 5-year project. He is completing the special wiring to implement all of the electronic functionality, and anticipates construction work to begin later this year. Construction is expected to be completed by mid-2019, with testing and burn-in finished in time for a debut of the "40-Year House" later in 2019.
The 40-Year House will be cybernetic, energy efficient, and maintenance free.
As you can imagine, developing such a house calls for lots of electronic components. He and his team are considering everything from flooring to the HVAC system, lighting, and yard irrigation. For example, the 3,450-square-foot, sensor-rich house will be able to turn bathroom exhaust fans, TVs, and LED lights on and off after sensing the location of occupants. The driveway would recognize when the occupants have returned home, open the garage door, and send an e-mail to anyone whose car is not yet in the garage to say, “Hey – I made it home OK.” The mailbox would alert when mail or packages have been delivered and reveal who delivered them – and who removed them. Should the home detect a fire, it would shut off gas lines, turn off fans, unlock exterior doors, call the fire department, and show the home’s floor plan and occupant locations on a front-door display that normally just shows the house number. The design team will be able to identify potential points of failure in the home, such as plumbing problems, warping wood, and cracks in the driveway. They’ll also be able to analyze causes of these failures, such as UV exposure, humidity, and strong winds. They’ve even come up with a way to avoid toilet paper outages. To minimize maintenance over a few decades, the house will be built with materials like engineered lumber and metal roofing.
Creating a cybernetic control system, in particular, calls for components like sensors to monitor relevant conditions, controllers to make the decisions on how to act, and actuators to turn the controller commands into actions. According to an article posted on Winston's 40-Year House website that provides a broad description of a cybernetic architecture for home self-control, memory will be incorporated into the system by connecting its roughly 100 intelligent nodes to and through a relational database. Readings collected by the system can be logged in the database, and any controller can then query the database for information to help it make its decisions. The control system will have the flexibility of trying different variations of its decision points, querying the database to assess which variations provide the best results, and then adjusting itself accordingly. Each of the small computers—about half have daughterboards carrying multiple sensors, rather than standing alone—becomes one node among many in a larger system, essentially a network of multiple nodes that connect to a single database. Notes the article, "With appropriate programming, this configuration can meet the definition of a cybernetic control environment: self-contained operation, situational awareness and adaptability."
In the proof-of-concept house, one node design connects a Raspberry Pi single-board computer to sensors that read ambient light, barometric air pressure, temperature, a thermal grid scanner, humidity, the open/closed status of the door, indoor air quality (based on readings of volatile organic compounds), three-axis vibration (through accelerometers), and more. Actuators include an amplified speaker, a control system for the ceiling fan, an infrared emitter to send TV remote control signals, and more. So far, the house design has 100 nodes. Any node connected to the database can know relevant readings from every sensor connected to any other node, increasing its intelligence by looking at any desired history of every relevant reading, according to Winston’s article.
"Designing a house that’s intended to last almost half a century without needing major repairs or replacements puts a lot of emphasis on longevity," said Winston. "If you consider the house to be a system and me to be an integrator, I have to also take design responsibility for creating environments that let components survive well beyond their MTBF, and to fully respect Murphy's Law by providing secondary systems and backups, as well as backups for the backups."
Among the electronic components in the 40-Year House are Maxim audio amplifiers and light sensors. When evaluating sensor solutions, Winston evaluated specs such as operating temperature range, accuracy, MTBF, and I2C compatibility. The team is using the MAX98357AEWL+ digital pulse-code modulation (PCM) input Class D audio amplifier, which is designed to deliver Class AB audio performance with Class D efficiency. The amplifier has five selectable gain settings and supports I2S data. In his review of the IC, Winston notes, "3.2 Watts of clean I2S audio from a Maxim Integrated MAX98357A Class D amplifier means the best sound in the least space for a Raspberry Pi or other I2S sources." The team is also using the MAX44009EDT+ ambient light sensor with analog-to-digital converter (ADC) and I2C digital output. At under 1µA operating current, the MAX44009 is the lowest power ambient light sensor in the industry. For the house project, Winston notes that the team appreciates several relevant features: ability to block infrared and UV light, extreme accuracy over an ultra-wide range, effectiveness from near darkness to very low light levels to very bright sunlight. Winston notes in his review of the IC: "From the low light levels inside ventilation ducts where the presence of light can indicate problems to light level sampling across an attic where brightness differences may flag problems to in-room ambient light readings that help determine lighting choices, the Maxim MAX44009 meets the need."
Ambient light sensing is, so far, proving to be an insightful capability to Winston and his design team. He explains, "There are 30 places we read ambient light inside ductwork—and with our cybernetic architecture, we can check current versus past or customary readings to derive even richer information from that resource. Air leaks are the enemy of HVAC systems; early detection can save a lot of time and trouble and money. Attic spaces and crawl spaces also have norms, deviations from which are better known than not known. We have a thermal map of the house, but if a temperature suddenly spikes, what does that mean? The sun coming through the window is a different ambient intensity than a candle or a space heater, and overlaying ambient light changes with temperature changes can help guide our cybernetics to a more intelligent interpretation."