1. Should the smart meter serve as the primary gateway for residential energy usage data, price data, and demand response signals? What are the most important factors in making this assessment, and how might those factors change over time?
The term "primary" can be understood as "the first" or "the main." This response addresses both potential interpretations.
Smart meters should serve as the initial gateway for residential smart grid energy information, thanks to the sizable deployments are underway today to install smart meters across utility service territories. The tens of millions of smart meters that are being deployed provide an obvious starting point for connecting residential customers to the smart grid. They already are networked for two-way communications; they can readily and inexpensively equipped with standards-based wireless hardware for HAN communications; and HAN-ready smart meters do not require any additional effort or investment for installation.
Smart meters also are well-positioned to serve as the main gateway for the utility to capture energy usage data and to communicate demand response signals into the home. Smart meters are connected to reliable networks with broad coverage, whereas residential broadband connections are better suited for web browser access to smart grid services than they are for sending usage data to the utility or to send demand or pricing signals to automated devices in the home. Broadband connections have several limitations as smart grid gateways, including:
Broadband connections do not offer utility-grade network reliability and will need costly customer- and field-support for energy management applications. Users frequently change broadband providers, experience equipment failures, change or forget wireless passwords, and modify network configurations and equipment. Any of these actions can interrupt communication between the smart grid and devices in the home. Responding to these changes will incur support expenses for utilities, and residential customers will find little benefit in having to maintain their own smart grid network connections.
Many Americans do not yet have broadband connectivity at home. The National Telecommunications and Information Administration (NTIA) found in February 2010 that 40% of Americans do not have high-speed internet access at home. Although this broadband connectivity will increase with time, especially with policy encouragement from Federal and State government, it will take many years and significant investment before access to high-speed internet approaches the utility-grade ubiquity necessary for residential broadband to serve as the primary gateway for smart grid connectivity.
2. Should a separate gateway (energy services interface) be the primary gateway for all or a subset of this data?
Home energy management systems should be able to access real time data from the smart meter via the home area network, but most homes will get the majority of the benefits from the smart grid with a capable smart meter communicating directly with a small number of devices in the home.
In the short term, the thermostat is the key device for smart grid-enabled energy services; in some areas electric water heaters are important; electric vehicles will become important as they grow in number; and appliances like pool pumps, electric dryers and dishwashers also will gain communication abilities eventually. This set of devices should be supported directly with the smart meter without the need for a separate gateway. Consumer-purchased home energy management systems that can communicate with the smart meter may be desirable for managing lighting, electronics, and other loads, but such investments will be appropriate and cost-effective for a relatively small percentage of households.
3. What alternative architectures involving real-time (or near-real-time) electricity usage and price data are there that could support open innovation in home energy services?
It is important to identify the important use cases for real-time electricity data. We believe there are three models for capturing higher resolution electricity data from the smart meter.
High detail: Capturing total power usage with a granularity of two minutes or less can reveal highly useful information about the performance of the home over long time periods. These data can be examined by software algorithms, energy efficiency professionals, and technically motivated homeowners to identify ways to use energy more effectively. We believe that advanced smart meter networks can capture this data using simple data reduction algorithms in the meter. Such an approach enables utilities to provide reliable, secure, and useful energy management services to their customers at a very low cost.
On-demand reads: It can be useful for an consumer or an energy efficiency professional performing a home energy audit to be able to quickly see how the load shifts when devices are activated and deactivated. For example, seeing the total house load increase by 1000 watts when the living room lights are turned on will quickly help estimate the costs of specific devices and activities. We believe this functionality can be supported directly with a capable smart meter and a web browser on a computer or mobile phone, without the need for any specialized hardware in the home. In our experience, a system in which an interested resident can observe the power usage curve in a home for short periods with a delay of a few seconds, using just a standard web browser, can provide powerful feedback and insight about energy consumption. We have witnessed this effect to be particularly engaging as a way for children and teenagers to learn about energy usage.
Continuous real-time display: The ability to continuously display real-time data on a device in the home, when the user may or may not be interested in such information, has limited utility. Such functionality can be accomplished with an in-home display or an energy gateway communicating over a broadband connection, but our field-based experience suggests that this functionality will not be of high value for residential customers. Limitations of continuous real-time display include:
It requires an unreasonable level of attention from the user to watch a display through the day.
It is difficult to extract useful information from a constantly changing number.
It is much more effective to examine historical patterns from and extended time period with software or an energy professional than the extract meaning from a constantly changing display.
It requires an additional hardware in the home that has material, energy and support costs.
Based on our user feedback and product research, high detail and on-demand reads are effective and can be supported with an advanced smart meter and a web browser, but the hardware for continuous real-time display does not merit the incremental cost.
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