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Home Area Network (HAN): The Smart Home

The Home Area Network (HAN) is the idea of being able to remotely monitor and control a home thus making it a smart home connected to the smart grid. A smart home has been a mainstay of science fiction for decades but now it’s becoming a reality. Your Home Area Network (HAN) is no longer only about internet access.

Why the Home Network?

The Home Area Network (HAN) has become a key focus area for the smart grid due to the large potential of energy savings and the ability to reduce peak energy loads on the overall smart grid. The HAN is a group of devices that monitor, control, and/or adapt to changing energy conditions. These devices are often connected to the utility network or the consumers' broadband connection. Devices often included in the HAN are thermostats, home energy displays, appliances, water heaters, lighting, electric vehicle charging stations, pool pumps, power strips, gateways (for example, a device that can convert ZigBee packets into Ethernet packets), and any type of load control devices. (See our plug meter reference below!)

Utilities are actively exploring the potential of the HAN and how to implement a flexible program to allow customers the ability to manage, control, and reduce energy. These programs assume the basic components of the Smart Grid, smart meter, and network support equipment that has been installed.

Case Studies

Time-of-Use (TOU): The HAN can help you save money!

Once the utilities have these basic components installed, they have the ability to implement Time of Use (TOU) or time-based programs. This type of program could reduce energy bills, but does have the potential to double or triple energy bills if not managed properly. TOU pricing is a variable pricing model that changes during the day as energy demand increases. For example, the peak time of energy usage for most utilities is during a hot summer day from 2:00 to 3:00 pm.

During this time, most AC units are running and factories are in full production. Utilities set the non-peak hours to lower rates compared to flat rates, but set peak hour rates to double or triple the normal flat rate. Depending on the season some consumers set their thermostats to higher or lower temperatures during the day to save energy, so TOU could be a good option for this type of consumer.

The Smart Home and Energy Reduction

In an effort to accelerate the roll out of the Smart Grid and energy reduction, the US government passed “The American Recovery and Reinvestment Act of 2009” that matches 50% percent of the development and deployment of Smart Grid equipment focused on reducing energy. The only catch is that the equipment must follow an approved NIST standard. This requirement helped push the creation of the Smart Energy Profile 2.0 (SEP 2.0) and has driven the ZigBee, WiFi, and Homeplug groups to support this new standard.

SEP 2.0 defines the process for exchanging application messages, the message structure, and device types. For example, a thermostat device type defines the accepted application messages and functions. The SEP 2.0 is independent of the PHY and MAC layers, but Zigbee, WiFi, and Homeplug are planning to support the SEP 2.0. Therefore, a company could create a SEP 2.0 thermostat and offer a ZigBee, WiFi, and Homeplug option without having to rewrite the application code. Another part of the SEP 2.0 is to give energy management devices an IP address and enable consumers to access these devices remotely.

Appliance manufacturers have also started developing appliances that are able to communicate on the different HAN networks. The idea is for the appliance to react to the given TOU pricing and inform the consumer. The consumer then has the choice to run the appliance or wait until the TOU pricing has been reduced. The appliance could also react to the TOU data by delaying functions like drying, defrosting, and cooling cycles.

Load control devices will have a significant roll in the HAN and smart grid. Load control devices plug into existing products inside and outside the home and control the power flow to a device. For example, a smart power strip is a form of load controlled device. A smart power strip could manage all the devices connected to a home computer. If the computer is turned off do the monitor, printer, speakers, and peripheral devices need to be on? The power strip could monitor the current and voltage for the computer and sense when the PC is turned off. The power strip could then shut down the peripheral devices connected to the PC via electronic relays.

Plug-in Hybrid Electric Vehicles (PHEV) could be a big driver of the HAN for the utilities. Today PHEVs are not an issue, but as they grow in popularity, they will represent a sizable energy load on the electrical grid. For example, if everybody started driving PHEVs and plugged in at 6:00 pm after they got home from work, the current grid would shut down. To prevent this scenario, utilities would like to implement TOU pricing for customers with PHEVs. In fact, some utilities have started offering networked PHEV stations and substantial discounted energy rates for charging PHEVs after 10:00 pm.

HAN and Renewable Energy

The last area the HAN is going to impact is micro energy generation via renewable sources installed by consumers. Today most of these systems are solar based, but wind is also a viable option. These systems use a separate electric meter to measure the energy generated by the consumer, but how are these systems going to be affected by TOU pricing? If the consumer has an energy storage system, the renewable could be used to charge the storage system. An energy manager could then dynamically manage the energy sources based on the current TOU. For example, you may want to run the PHEV charging system off the renewable energy source during peak hours of the day, and then switch to the normal power grid during the lowest energy rate period.

The HAN has a huge potential to change the way we live and use energy in the home. As new advancements and policies are released, the HAN market will continue to change and be more adaptive. FES is committed to providing the latest products and services to assist in the development of new HAN connected devices.

Frequently Asked Questions

Questions

This question depends on your location and what communications standard your local utility has decided on for their smart meter rollout.

Discussions center around Zigbee and Wifi for North America, with a growing interest for Power Line Communication (PLC).

In Europe PLC has been a major focus with some interest in Wifi, sub Ghz RF networks and wireless M-Bus.

In Asia the focus has been on Wifi and sub Ghz RF networks.

The main concern for utilities is interoperability or the ability for all of these devices to communicate with each other. Standards have been slow to be adopted, with some utilities implementing their smart meter rollouts without a national standard in place. The important piece for any home area network will be the ability to communicate with new devices as they become available.

Load balancing involves turning loads on and off in order to maintain a steady amount of energy being used by a home, office or factory.

In the context of the Home Area Network (HAN) this would involve the control of devices within the home to maintain energy use at less than a pre-determined value at any one time. This is particularly interesting for the consumer in areas where pricing is determined by the load profile or amount of energy a house is using at any one time.

For some utilities, lower pricing is offered if the load of the home at any one time remains under a defined maximum value.

Intelligence embedded in the electrical items we use every day can automate energy savings by reacting to events and user input. For example, there are plug strips that will turn off peripheral devices such as printers when the computer goes to sleep.

Other forms of energy savings can come from user input on when they leave their home. For example, a pre-programmed set of instructions can be executed if the user indicates they are leaving home for work for the day. Water heaters could be shut off until a pre-determined time, all indoor lights could be turned off, entertainment centers could be shut down completely rather than being left on standby, closing blinds if the sun is heating up your house when you aren’t home, etc.

A monthly electricity bill shows your usage for the month, but doesn’t break down what uses the most power. Intuitively we know that the larger appliances in our homes and offices are the culprits, but what are the hungriest devices? Embedded energy measurement can help determine the running cost of major electric devices and adding communication and relays to turn these devices on and off can help to control their use.

See our Reference Design