1. Microcontroller-based Smart House for Improved Energy Efficiency
Summary

2. The Problem
Reducing the energy footprint at the individual level can have a
major impact on total energy and environmental costs
A typical U.S. household could save 25% of its $1,900 yearly energy bill and over 2.5 metric tons of CO2 through improved energy efficiency
Automated techniques will play a major role in efforts to increase energy efficiency
Small, very-low-cost microcontrollers will be a key enabling technology in this effort
Many microcontroller manufacturers are introducing lines of smart microcontrollers for applications ranging from solar panels to intelligent air conditioner control

3. Lessons Learned: Microcontrollers
Microcontrollers provide a low-cost, effective means of controlling processes that might be encountered in a temperature control problem
Microcontrollers feature
low cost
high degree of integration
large amount of on-board memory
large amount of I/O
Microcontrollers are programmed at a relatively low level
A typical household may have as many as several dozen microcontrollers controlling microwave ovens, wireless phones, computer printers, etc.
A typical midsize car may have 50 or more microcontrollers

4. Tin (t) = Tout + Tin (0) - Tout) e-t/
Lessons Learned: Heat Loss and Newton’s Law of Cooling
Sources of heat loss in house
conduction
convection
radiation
Newton’s law of cooling:
The temperature inside a body in contact with an outside body at a lower temperature will cool at a rate given by
Tin (t) = Tout + Tin (0) - Tout) e-t/

5. Lessons Learned: Thermoelectric Effects
Peltier effect: when a junction is formed between two dissimilar metals, a current passed between them will produce a transfer of heat from one to the other
the rate of heat transfer is proportional to the current and the difference between the Peltier coefficients of the two metals
the reverse effect (Seebeck effect), in which a voltage is produced if the metals are held at different temperatures, is the basis for the thermocouple, used for measuring temperature
Efficiency ~20% of a typical refrigerator
Historically used to cool semiconductor components (microprocessors, semiconductor lasers, etc.
Growing use in portable coolers/chillers (now available as USB drink coolers)
Reversible (use as heaters or coolers)

6. Energy Tradeoffs Oil Easy to handle, store and transport
Easy to extract
Nonrenewable resource
Burning produces CO2
Numerous environmental safety hazards
Coal
Abundant resource (although non-renewable)
Low cost
Mining damages environment
Emits pollutants even with anti-pollution measures

7. Energy Tradeoffs Nuclear Cost effective
Lowers reliance on fossil fuels
Limited pollution
Waste is radioactive (long half life)
Mining damages environment
Safety is a major issue
Natural Gas
Minimal pollution
Nonrenewable
Environmental impact of exploration

8. Energy Tradeoffs Wind Low environmental impact Safe High cost
Requires alternative source as backup
Impact on local fauna
Tidal
Low maintenance cost
Predictable
Expensive to build
Few suitable sites

9. Energy Tradeoffs Solar Renewable Safe Low environmental impact
Small plant footprint
High cost
Geothermal
No pollution
Geographically limited

10. Potential Benefits to Society
Substantial cost savings at the individual and societal level
Reduced reliance on nonrenewable resources
Reduced damage to the environment
Reduced impact on global climate
Reduced geopolitical tensions