Monitoring and control systems to mitigate energy use in residencesMarch 24, 2007Eric WilliamsDepartment of Civil and Environmental Engineering & the School of SustainabilityArizona State UniversityFULTONs c h o o l o f e n g i n e e r i n g Residential Energy Use in U.S. 21% of total US energy in 2004– Increased 16% in last 4 years Structural shift: electrification (47% of primary energy in 1978 versus 54% in 2001) Energy intensity (energy/ft2) roughly constant 1980-2000 House size increasing (1500 ft2in 1970 -> 2,350 ft2 in 2004 for avg. new home)FULTONs c h o o l o f e n g i n e e r i n g Structure of Household primary energy use Energy use per household (MJ) Energy Share Expenditures per household ($)Space heating 53,000 29% 480 AC 19,000 10% 197 Water heating 23,000 13% 203 Appliances 88,000 48% 670 Total 183,000 1,550 Source: US DOE RECS Survey 2000FULTONs c h o o l o f e n g i n e e r i n g Technical versus Service efficiency  Technical efficiency: measured at product/process level (e.g. mpg of automobile, SEER rating of air conditioner) Service efficiency: measures delivery of delivery of energy service (mobility, climate control) – larger scope including additional external conditions and behavioral aspects.FULTONs c h o o l o f e n g i n e e r i n g Monitoring and Control systems Monitoring and control systems often play a important role in improving service efficiency  Deliver energy (or water) only when and where needed Provide feedback to inform efficiency decisions Widely adopted in manufacturing and business operationsFULTONs c h o o l o f e n g i n e e r i n g Monitoring and Control Technologies in Buildings Elements: Smart meters Networked thermostats, (X10, ZWave, WiFi) Controllable vents (for zone heating) Sensors (temperature, light, energy) Software systems and graphical interfacesSystem examples: Remote control of HVAC via cellphone,  Time pricing, peak shifting, remote meter reading for utilities  Information system to provide feedback to residents on home energy useFULTONs c h o o l o f e n g i n e e r i n g Status of monitoring and control technology adoption in residencesControl:  Mainstay is programmable thermostats: 27% adoption in 2001. Most programmable thermostats are not actually used.  Central HVAC (in US, Japan, for instance, is all room-by-room)Monitoring: Monthly billing statement (or sneaker-pencil net)FULTONs c h o o l o f e n g i n e e r i n g Status of monitoring and control technology adoption in residencesHuge technology gap between:On the desk On the wallFULTONs c h o o l o f e n g i n e e r i n g The research questionIs there potential to instigate changes in monitoring/control/behavior so as to substantially reduce home energy use?Working hypothesis: there could purely economic rationale for households to adopt, but suppressed by “behavioral” market failuresFULTONs c h o o l o f e n g i n e e r i n g Earth systems engineering & management (ESEM)1. Characteristics and dynamics of systems as systems2. Identify real world system linkages3. Evaluate, then implement4. Minimum needed intervention5. Not only science/technology, important political/human dimensions6. Recognize difference between technical engineering and social engineeringFULTONs c h o o l o f e n g i n e e r i n g ESEM for Energy smart homes/consumersSome important aspects of the system: Technical engineering – pilot/feasibility done for variety of monitoring/control systems (mostly past R&D stage).  Consumer – what are cost/benefits of different systems? willingness to pay, pedagogy requirements Private sector – utility pilot projects and programs (e.g. peak shifting), IT manufacturers – firm structure, economies of scale should be analyzedFULTONs c h o o l o f e n g i n e e r i n g First step: Characterizing “Unneeded”energy use A. Heating/cooling of unoccupied housesB. Heating/cooling of unoccupied roomsC. Overheating/cooling due to temperature variations D. Leakage/standby powerE. Appliance choiceFULTONs c h o o l o f e n g i n e e r i n g A. Heating/cooling of unoccupied houses Based on DOE Residential Energy Consumption Survey (RECS), only 11% of people turn off heating when not at home No observable difference in thermostat settings 54% of residents responded that noone is home on a typical workday Using the above, estimate that 100 1010MJ are used heating unoccupied homes, 5.2% of primary residential energy use.  Similarly, air conditioning empty homes accounts for 1.8% of household energy use.FULTONs c h o o l o f e n g i n e e r i n g B. Heating/cooling of unoccupied rooms According to RECS, on average 46% of home area is bedrooms, assume that heating the remaining 54% for 8 hours every night can be counted as unneeded energy.  Allocating proportional to area and time used, total wasted energy heating non-bedroom spaces is 140 1010MJ, or 5.2% of total primary energy.  Using similar assumptions, including air conditioning total increases to 7% of primary energy.FULTONs c h o o l o f e n g i n e e r i n g D. Leakage/standby power Many appliances, such as TVs, VCRs and stereo equipment draw electricity even when turned off: leakage/standby power Researchers at the Lawrence Berkeley National Laboratory estimate that 44.7 TWh of electricity is lost as leakage current. Their definition of leakage includes devices turned off and in standby mode. This corresponds to 49 1010MJ, or 2.5% of primary household energy consumption.FULTONs c h o o l o f e n g i n e e r i n g E. Appliance choice Qualitatively distinct from previous categories: considers hardware itself, rather than how used. Wide variation of efficiencies for different models of appliances Monitoring systems could make consumers more aware of costs to operate per appliance, thus affect decision.  Unneeded energy use is gap between current stock and efficient. Different ways to think about defining efficient stock. Future work, for the time being borrow figure from Koomey et. Al (1998) on efficiency standards, suggesting 15% gap.FULTONs c h o o l o f e n g i n e e r i n g Summary of Preliminary evaluation~40%Total15%300E. Appliance choice2.5%49D. Leakage/standby power3%65C. Overheating/cooling due to temperature variations 13%260B. Heating/cooling of unoccupied rooms7%136A. Heating/cooling of unoccupied