Building connected, pervasive, human-facing, and responsive applications that incorporate local sensors, smartphone interactions, device actuation, and cloud-based learning--the promised features of the Internet of Things (IoT)---requires a complete suite of tools spanning both hardware and software. We present a set of these pieces, including a gateway, four hardware building blocks, multiple sensor platforms, an indoor localization system, and software for connecting users and devices. Each piece plays an integral role towards enabling applications, from facilitating rapid development of wireless smart devices to composing data streams and services from a diverse set of components. By providing layered interoperable systems, our toolkit offers cohesive support for moving beyond single-device, cloud-centric applications---typical in today's IoT landscape--and towards richer applications that incorporate multiple data streams, human interaction, cloud processing, location awareness, multiple communication protocols, historical data, access control, and on-demand user interfaces. To show how the pieces in the toolkit cooperate, we demonstrate a location-based access control application where a user's smartphone can control a room's lighting, but only from within the room. Further, data streams from the phone and nearby sensors are used to provide a constant lighting service which attempts to maintain a user-set brightness under variable external lighting conditions.

We present PowerBlade, the smallest, lowest cost, and lowest power AC plug-load meter that measures real, reactive and apparent power, and reports this data, along with cumulative energy consumption, over an industry-standard Bluetooth Low Energy radio. Achieving this design point requires revisiting every aspect of conventional power meters: a new method of acquiring voltage; a non-invasive, planar method of current measurement; an efficient and accurate method of computing power from the voltage and current channels; a radio interface that leverages nearby smart phones to display data and report it to the cloud; and a retro power supply re-imagined with vastly lower current draw, allowing extreme miniaturization. PowerBlade occupies a mere 1" × 1" footprint, offers a 1/16" profile, draws less than 180 mW itself, offers 1.13% error on unity power factor loads in the 2-1200 W range and slightly worse for non-linear and reactive loads, and costs $11 in modest quantities of about 1,000 units. This new design point enables affordable large-scale studies of plug-load energy usage--an area of growing national importance.

We present PowerBlade, the smallest and lowest power AC plug-load meter that measures real, reactive and apparent power, and reports this data, along with cumulative energy consumption, over an industry-standard Bluetooth Low Energy radio. Achieving this design point requires revisiting every aspect of conventional power meters: a new method of acquiring voltage; a non-invasive, planar method of current measurement; an efficient and accurate method of computing power from the voltage and current channels; a radio interface that leverages nearby smart phones to display data and report it to the cloud; and a retro power supply reimagined with vastly lower current draw, allowing extreme miniaturization. PowerBlade occupies a mere 1" by 1" footprint, offers a 1/16" profile, draws 176 mW continuously, offers 1.13% error on unity power factor loads in the 2-1800 W range and slightly worse for non-linear and reactive loads, and costs $11 in modest quantities of about 1000 units. This new design point enables affordable large-scale studies of plug-load energy usage -- an area of growing national importance.

Obtaining a detailed, whole-house breakdown of energy usage would allow for homeowners to better understand their energy consumption and opportunities for energy savings. Current solutions are either too course-grained, too difficult to deploy, not networked, or offer incomplete coverage of hard to meter items, such as ceiling lights. We demonstrate a wirelessly networked, energy-harvesting power metering system that draws zero standby power and is power proportional to the load it is metering.

Conventional AC power meters perform at least two distinct functions: power conversion, to supply the meter itself, and energy metering, to measure the load consumption. This paper presents Monjolo, a new energy-metering architecture that combines these two functions to yield a new design point in the metering space. The key insight underlying this work is that the output of a current transformer -- nominally used to measure a load current -- can be harvested and used to intermittently power a wireless sensor node. The hypothesis is that the node's activation frequency increases monotonically with the primary load's draw, making it possible to estimate load power from the interval between activations, assuming the node consumes a fixed energy quanta during each activation. This paper explores this thesis by designing, implementing, and evaluating the Monjolo metering architecture. The results demonstrate that it is possible to build a meter that draws zero-power under zero-load conditions, offers high accuracy for near-unity power factor loads, works with non-unity power factor loads in combination with a whole-house meter, wirelessly reports readings to a data aggregator, is resilient to communication failures, and is parsimonious with the radio channel, even under heavy loads. Monjolo eliminates the high-voltage AC-DC power supply and AC metering circuitry present in earlier designs, enabling a smaller, simpler, safer, and lower-cost design point that supports novel deployment scenarios like non-intrusive circuit-level metering.

We explore the seemingly trivial problem of scaling the AC power meter to a cubic-inch form factor. This small volume, necessary for unobtrusive inline plug-load monitoring, requires aggressive electromechanical codesign and 3-D electronics packaging. However, the key scaling challenge across both size and efficiency lies in the power supply architecture and load power. Hence, contrary to conventional wisdom, power is not free, even if a device is attached to wall power. Since many existing power supplies exhibit high baseline power draw, this leads to poor efficiency and runs counter to the green goals of many applications. We claim there are two paths to scaling the plug-load meter to a space- and power-efficient design point without sacrificing measurement fidelity: (i) by duty cycling in some cases and (ii) by using an off-line switching regulator that is not capacitor-fed. To evaluate our claims, we design a modular power meter architecture, implement several design alternatives, and evaluate their size, efficiency, and cost. We show that an energy-efficient, cubic-inch-sized wireless power meter is viable. Our design is 10x smaller, draws 3x less standby power, and still offers equivalent measurement fidelity as the best previously reported results.