Motion System Brings ‘Smart House' to Life

Virginia Tech's Lumenhaus, a recent first-place winner of the 2010 Solar Decathlon Europe, is an 800-sq-ft energy-optimized "smart" home that leverages an active system of motion controls to minimize the overall HVAC load on the house.

"The thought behind the Lumenhaus design was to build a sustainable smart house with the ability to maintain optimal energy performance at all times. So when the weather is good the house automatically opens up and doesn't use energy," says Professor Joseph Wheeler, the project coordinator at Virginia Tech. "Conversely, when the weather turns bad a system is in place that enables the house to protect itself."

Lumenhaus epitomizes a "whole building design" construction approach, in which all the home's components and systems have been designed and built to work together to maximize user comfort with environmental protection. At its heart is an integrated environmental control system powered by motion control products from Kollmorgen and Thomson.

"To create a more energy-efficient house, the idea was to protect the glass in the house when the weather becomes extreme," says Wheeler. "But we didn't want to lose beautiful, natural light in the house. We started by designing polycarbonate panels filled with aero gel insulation, but the initial challenge was how to drive the panels back and forth over the facade of the house."

The system uses a series of belt-driven linear actuators, supplied in a custom size, and servomotors to drive 18-ft-wide panels over the main living spaces and 9-ft-wide panels over the bedrooms. A Siemens APOGEE building control system controls 10 stops in the system and is programmed so that if wind gusts reach 30 mph, for example, the systems sends a signal to close the panels to protect the house.

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"The house has its own weather station with a 'passive/active' environmental control system to minimize energy consumption and maximize efficiency. In short, the weather station communicates with the control system, which in turns tells the Thomson and Kollmorgen motion system whether to open or close the house. When the house needs insulation, insulation screens close; when the house needs shading, shading screens close; and when the house needs security, the shade screens close without blocking natural ventilation," explains Wheeler.   

Click here for a video of Virginia Tech's Lumenhaus.

Lumenhaus' layered systems use the series of motorized shade screens and insulation panels to adjust to changing weather patterns. The screens and panels can weigh up to 1,000 lb each, and coupled with potentially high dynamic loads from exposure to changing environmental elements, the tools that move them need to be extremely robust.

The shade screen assemblies ride on Thomson 60 Case^® low profile round rail assemblies with Super Smart Ball Bushing^® bearings, and are run by Thomson RapidTrak belt-driven Linear Motion Systems powered by Kollmorgen AKM^™ Servomotors. The insulation panels and shade screens serve as the "clam shell" that protect the house against the elements, and which are hung and moved by RapidTrak systems with Kollmorgen AKM servo motors. The house also uses Thomson PPA PowerPac Actuators as part of a photovoltaic array that tracks and generates power from the sun, and that automatically adjusts to accommodate for changes to the angle of the sun on a seasonal basis.

"Variable feedback provides a certain level of speed and power control, and in dabbling with the overall energy control we've been able to move the panels at up to 300 inch per minute, if needed, using just 1.5A of power. Using such a small amount of energy to operate these panels can have a big impact, as it means we don't have to turn on HVAC systems," says David Clark, the student team leader at Virginia Tech. "Of course power needs vary depending on weather conditions and the changing dynamic loads from high winds and changes in wind direction, so sometimes we need to tweak the power to optimize performance; the bottom line is that we're able to do so in such a way as to control consumption and maximize efficiency."

Lumenhaus constantly monitors weather patterns and automatically adjusts the shade screens and insulation panels as needed, so Virginia Tech engineering students used a 1-10 Micron^® NemaTRUE Planetary^® Gearhead from Thomson inserted between the Kollmorgen AKM Servomotor and track drive to increase torque potential, and to help slow the motor down so panels don't move too fast. "Generally speaking we don't need 10,000 different stops, we just need to reliably get to the right position," says Clark.

Because there are times that demand a manual override, Lumenhaus utilizes an iPhone and iPad as the interface element, along with Kollmorgen S200 Servo Drives with digital and analog inputs, to help manually override the building control system.

"The building control system takes the information it receives from the iPhone or iPad, interprets it from 1-10, then sends a low-voltage signal out to each servo drive (0-10V). When the drive receives the information it interprets it into an exact position count, and then sends the screens and insulation panels to the correct position," explains Clark.

The iPhone and iPad automatically orient the floor plan of Lumenhaus, and with one swipe of a finger not only can users override the control system to reorient the screens and panels, but they can also be used to remotely control any number of aspects of the house, including locking or unlocking doors.

"What's really interesting about some of the concepts brought to life in Lumenhaus is that it gives us a picture of how, on a smaller scale, existing residential and commercial buildings could be made more energy-efficient by retrofitting them with smarter louver-type systems that not only shade but also insulate," says Robert Dunay, director, Center for Research, Virginia Tech.

"For example, the ability to have a control system that automatically responds to and even harnesses what the weather gives through means such as blinds, shades and shutters that know where the sun is and can adjust accordingly is potentially pretty significant when it comes to minimizing HVAC use and power consumption."      Automation provides a way to intelligently control the environment in the house. But Wheeler says the reaction from the public to automation is often that "I don't want my house to be complicated." He says he tells them, "look at your automobile or an airplane. Everything else in life has embedded electronics in it so why are we afraid for housing to move forward."

A next step is simplifying the building control system. The overall control is more advanced than what is needed, and one task would be to look at residential scale controls to control the shade and insulation screens.