Pro-Active Residential Energy Management

Transcription

1 Pro-Active Residential Energy Management Kenneth Wacks, Ph.D. Home & Building Systems Consultant Chair of International Standards Committee Tel: (781) ; Fax: (781) Energy Management Today When the price of oil rose substantially in the 1970s and 1980s, I asked my neighbor whether he thought my house had insulation in the walls. He chuckled and told me that traditional New England construction was based on oil costing $1 a barrel! Yankees bought oil to deal with the cold, rather than insulate the walls. Today, homebuyers assume that new houses are well insulated and expect to receive reasonable bills for heating and cooling. For most of the 1990s, energy prices have been stable. However, this has changed recently as a result of political problems in Venezuela and the Middle East. Once the present crises are resolved and business starts improving, we may still face higher prices due to increased energy demands for manufacturing and travel. Longer term, the supply of crude oil is predicted to last only about 40 years. Thus, it is prudent for architects and home system engineers to incorporate energy management in building designs so we are prepared for future price increases. Energy management today is based on improving building components and appliances, such as: Higher R-factor walls and roof insulation Double- and triple-glazed windows Heating and cooling (HVAC) units with efficiencies above 90% Multiple HVAC zones with controllable dampers Highly-insulated water heaters Energy efficient appliances All these products have had an impressive impact on reducing energy bills while maintaining a comfortable house. For the next quantum leap in energy efficiency improvement, we need to take a systemsview of the house and the fuel supply. The building must be designed with systems that adapt to the outside environment and to the rising cost of energy. For most of North America the price for residential electricity, gas, and oil is based on a fixed tariff. However, some utilities are -1-

2 considering tariffs that would expose customers to market fluctuation via time-of-use or realtime pricing for energy. This article presents an overview of potential solutions to building and appliance designs that can accommodate changes in energy costs with minimal impact on occupants budgets and daily activities. The good news is that next energy crisis is not upon us yet. However, architects and home system designers need to prepare for the inevitable and to be aware of plans by the utility industry. A pro-active stance for energy efficiency will serve customers far better than reacting to the next energy price spike or shortage. The NET-0 House The ideal house is constructed for NET-0 energy consumption. This means that on balance, the house consumes as much energy as it generates, but not necessarily simultaneously. Therefore, the house is still on the utility power grid. This ideal house can become a reality based on research at MIT (the Massachusetts Institute of Technology). The MIT Home of the Future is a research laboratory in the School of Architecture and Planning affiliated with the famous MIT Media Lab. This lab has a very practical mission: make a major change in the design, construction, and infrastructure of houses. To accomplish these goals, the MIT Home of the Future is examining the combination of architecture and home systems. Home systems will be part of an integrated package of features and services. Thus, through proper design, home systems will become essential features in housing. The market for home systems has been slow to expand because such systems have been viewed as luxury addons to houses Energy management is a priority at the MIT Home of the Future. The most important contributor to NET-0 is the building itself: location, design, materials, heating and cooling, windows, and window coverings. Net-0 energy consumption is accomplished through careful systems design of the structure. Figure 1 shows how the roof can function as an integral part of the house ventilation system. Thus, the roof becomes an active component in the HVAC system. MIT is also exploring the value of non-intrusive continuous user education to motivate behavior change. The user can be an important player in achieving Net-0 energy consumption. Education about energy conservation does not require formal study, but can be integrated into daily activities. To demonstrate this theory, researchers built a platform for informal education into the kitchen table. This way home occupants can see the consequences and costs of their decisions about energy usage. Figure 2 shows the technology incorporated into a table built in the lab. The tabletop consists of translucent glass so an image projected from below is visible on the table. The temperatures in the house are projected onto the table in Figure 3 with the status of the HVAC. Also displayed is the energy consumed by lights and by the air-conditioner. Alternate display formats present energy information and consumption data as text and as a pie chart. In general, the researchers found that users prefer information presented in small amounts at a time using simple and clearly understood terms. For example, when you are about to use more energy, you -2-

3 might be presented with choices, like opening the appropriate windows rather than turning on the air-conditioner. Utility Energy Management The NET-0 building is predicated on sophisticated materials and systems for efficient use of energy. Even in a NET-0 house, some energy must be purchased from a public utility. Therefore, it is important for building designers to be aware of utility plans for managing customer use of energy. This section examines current practices and plans for innovative pricing schemes by some electric utility operators. For most of the twentieth century, managing an electric or gas utility was a low-risk business. State regulators established tariff policies that encouraged utilities to expand by basing allowable profits on the assets constructed. Utilities responded by building generation plants and transmission facilities to stay ahead of the growing customer demand. Investors turned to utilities for stable and generous dividends. (Stability was upset only during some nuclear plant problems.) Major changes that began about 10 years ago have resulted in profound shifts in the electric industry: In 1992 the United States government initiated a process to move the utility industry toward competition. Some state regulators instituted Integrated Resource Planning that encouraged utilities to balance supply and demand concerns. Customer sensitivity and resistance to price increases have been growing. Environmentalists have made the public aware of the limits to expansion. Utilities have responded to these new pressures by instituting programs to manage customer demand. Such energy management programs are called Demand-Side Management (DSM). DSM ranges from subsidized building insulation to rebates for energy-efficient appliances to load control. Load Control Load control is an effective method of DSM that is currently applied to about 4% of all U.S. customers. There are three versions of load control. Local Control The utility publishes rates that typically include peak-time and off-peak pricing. The customers are responsible for deciding which appliances to operate when. Direct Control -3-

4 The utility turns off and on certain appliances, usually the water heater and/or airconditioner, via remote-control signals. These signals might be sent by radio, telephone, or on the electric power lines. Utilities usually compensate customers up to $10 per month for permission to exercise this control. Distributed Control The utility may vary the price at any time in response to market conditions. Energy management technology in the home assists the user to determine the economical time for operating various appliances. More than 90% of load control programs in the U.S. have used Direct Control. However, Distributed Control offers distinct benefits to customers and utilities. The utility can adjust customer pricing to reflect fluctuating energy costs. It is possible to design a Distributed Control system that combines simplicity with effective management of energy expenditures. Such a system shields the customer from confusing energy parameters such as the kilowatt-hour (kwh) consumption of an appliance. The following scenario is an example of how a user might interact with this system: It is 4 PM and the user is about to run the dishwasher. The following message appears on the appliance display panel: Save 25 by delaying the wash until 7 PM. Wash now: YES or NO? The user makes a simple decision based on criteria that are understandable: Do I need the dishes cleaned in the next three hours (perhaps for a dinner party at 7 PM), or can I wait and save some money? This makes buying energy as simple as shopping at a retail store. Thus, a well-designed Distributed Load Control system presents the user with simple choices while allowing utilities to adjust to fluctuating energy costs. Real-time Pricing of Energy Wide-scale deployment of Distributed Load Control has been deferred until there are mandates or market impetus for real-time pricing. A system to receive and process real-time utility price data for effective energy management has been designed in prototype form. Figure 4 illustrates the major components of such a system. The utility sends pricing data electronically to all houses in real-time over a network, such as the Internet or cable TV. This pricing signal enters the house through a residential gateway. A residential gateway interconnects a public network, such as the telephone or cable TV, with a home network. Control signals are sent to the major energy consuming appliances via the home network to control when and in what modes they operate. A key element in this system is the Energy Management Controller (EMC). The EMC is a specialized computer that receives the electricity rate data from the residential gateway and applies sophisticated software algorithms to determine which appliances to operate and when. The EMC could be a personal computer or could be embedded in a cable -4-

5 TV set-top box, a security system, or an appliance. The functions of the EMC are illustrated in Figure 5. The EMC is programmed to determine how and when to operate appliances based on the cost of energy, the energy requirements of the appliances, and user inputs. The user may specify a monthly energy budget (for example, $75 per month) and preferences (shower at 8 AM, air-conditioning at 6 PM, sauna at 8 PM, etc.). The customer should always be able to override decisions of the EMC. The effectiveness of the residential energy management system in meeting the budget and convenience goals of the occupants is limited by the ability of the EMC to control appliance energy usage. Some appliances, like refrigerators, cannot simply be switched off to save energy. With appropriate appliance design it is possible to defer certain energy consuming functions without affecting performance. For example, the defrost cycle in a freezer might be delayed a few hours when the energy price is lower without damaging the appliance. For the most effective energy management, manufacturers need to design appliances with operating modes that can be selected by the EMC. Some appliance companies are examining these options and have proved that there are no technical or cost challenges to facilitate energy management. They are waiting for a market imperative or subsidies from a utility company. Practical Energy Management Very few utilities in the United States have implemented load control with time-of-use or real-time pricing. In striking contrast, some European countries have deployed load control extensively for decades. For example, the major utility in Italy, ENEL, controls the demand for electricity by penalizing the usage of too much power at one time. As the graph in Figure 6 shows, high rates are imposed for consuming 3000 watts at one time, and a breaker cuts the house off the grid at 4500 watts. This is not a lot of power. A heater and dishwasher operating simultaneously can trigger a power cut with this tariff. An Italian appliance company has developed a clever method for overcoming this limitation so many appliances can operate simultaneously. The appliances coordinate their energy consumption to keep the total load within the ENEL limits. Merloni Appliances of Fabriano, Italy sells kitchen appliances in Europe, Asia, and Australia. At the beginning of this decade, Merloni introduced networked appliances. The networking of appliances was an outgrowth of developing smart appliances. Smart appliances use internal sensors combined with fuzzy logic and neural networks to tailor appliance performance to the load, such as the clothes or dishes, without the user making any front-panel selections. When appliances are networked, a wide variety of new applications are possible. Examples include a common user interface shared by many appliances, remote appliance servicing, access to user instructions for appliance operation, and energy management. Smart Appliances are not appliances of the future. The installed base of appliances with intelligent digital electronics has been growing substantially this decade. Merloni now includes smart electronics in about half of the 12 million units sold per year. Energy management needs in Italy actually prompted Merloni to develop networked appliances. The solution to the energy restriction in Italy is a combination of power metering with networked smart appliances as shown in Figure 7. The appliances communicate with each -5-

6 other and establish priorities to keep essential functions operating while avoiding the power ceiling. So far, no utilities in the U.S. are considering this approach. However, if energy shortages develop, we may have demand-side management imposed here. The key message here is that we can have our cake and eat it too! We can conserve energy without curtailing our daily activities. Home Network Infrastructure American appliance companies are investigating applications of networked appliances, but have not started mass marketing yet. Nevertheless, now is the time for architects to incorporate pathways for home networks, such as raceways and chases, into residential designs. This will facilitate not only distributed load control, but also sophisticated entertainment systems and eventually home automation for integrated lighting, comfort control, and security. Most major homebuilders have started to respond to consumer demands for home network wiring. About 40% of new houses have some network wiring. A home network is based on Local Area Network (LAN) technology used in offices. Multiple media types are likely, including twisted-pair wires, coaxial cables, and non-wired media. Non-wired media include communications over the electric power line, radio frequency (RF), and infrared (IR). Fiber optics has limited deployment in home networks. Even though RF networks such as WiFi are becoming popular, the most reliable media for a home network are wire-based. The home network has access to the outside via a residential gateway. Remote access might enable the home occupant to change the heating or security remotely, for example before returning home or to allow a repairperson into the utility room. Pathways to the house may include analog and digital telephone (DSL), cable TV, radio, satellite, and even signaling via electric power lines, possibly using Internet communications. There may be more than one residential gateway and multiple distribution panels. An international standard for the residential gateway, called HomeGate, is nearing final approval. The U.S. Telecommunications Industries Association and the Canadian Standards Association have issued standards for home wiring to support these applications. In addition, an international wiring standard is under development. Typical home network cabling includes one or two coaxial cables and four or eight twisted-pairs of wires, each of much higher quality than typical telephone wire. Products from various suppliers are shown in Figure 8. Good quality wiring must be complemented with high quality connectors and skilled installation to avoid damaging the components. Effective Energy Management The researchers at the MIT Home of the Future have concluded that effective energy management requires a combination of technology, such as load control, proper building design using efficient components, and user education so energy consumption choices are made wisely. -6-

7 As Figure 9 illustrates, energy management is achieved through a systems design approach that combines innovative materials with a multi-purpose building structure using proven technology. Copyright 2003, Kenneth P. Wacks Dr. Wacks has been a pioneer in establishing the home systems industry and a management advisor to more than 80 companies. Corporate managers depend on Dr. Wacks to identify business trends with practical and impartial information relevant for product and market development. At the MIT Home of the Future he is advising the program director and staff on integrating home systems into building architecture. The Consumer Electronics Association (CEA) chose Dr. Wacks to chair the international committee that created HomeGate, the residential gateway standard, and is writing the structured cabling standard. For further information, please visit kenn@alum.mit.edu, or call (781)

8 Convection flow Solar heat Solar light Figure 1 Active Roof HVAC Component -8-

9 Figure 2 Kitchen Table Education -9-

10 Figure 3 Displays to Motivate Energy Conservation -10-

11 Utility Power Energy Management Controller HVAC Water Heater Meter Utility Price Data Res. Gateway Home Network Dish Washer Refrigerator Inside House Figure 4 Distributed Load Control System -11-

12 Cost of energy Usage data Energy Management Controller Appliance rating Appliance control User energy budget User preferences Figure 5 Energy Management Controller -12-

13 Power consumption 4.5 kw 3 kw Black-out zone High rate zone - No limits on using home appliances - No black-outs - Low electricity rate Time Figure 6 Energy Management in Italy -13-

14 Power Meter Pmax=3kW Current Meter Appliance Network 2.8 kw 12: kw Each smart appliance reduces power consumption to achieve Pmax 0.3 kw 2 kw 0.3 kw TV Other electric loads Boiler 2 kw Figure 7 Energy Management in Italy using Smart Appliances -14-

15 Figure 8 Structured Cabling Components -15-

16 Distributed Load Control + Efficient Building Components & Design + User Education about Energy Conservation Figure 9 Effective Energy Management -16-