3. Home energy explorer \(Electrical Engineering\ Chapter\)

GregLawson edited this page Oct 25, 2011 · 3 revisions
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Software and suggested hardware infrastructure for exploring and making sense of home energy consumption and production.

Table of Contents

Related Projects

Incremental Growth

With a scalable home architecture, you should be able to start with a single sensor and later expand to more sensors as your desire for data expands. With one temperature sensor you know what the temperature is in a certain point, but with a second sensor you can estimate heat flow, and with multiple sensors you should be able to differentiate heat flow, solar heating, insulation and weather stripping effectiveness.

Wiring Architecture

Currently the least expensive and most reliable way to monitor an entire house is through Cat5/Cat6. Cat5/6 cabling is inexpensive, widely supported (Ethernet, telephone, serial) and can be wirelessly extended via WiFi. Powerline interfaces seem to scale poorly and have high error rates. Wireless interfaces promise to reduce cabling costs, but other than WiFi are often expensive proprietary interfaces. OpenWRT has a WDS mode that looks promising for a hybrid Wifi and cable solution. Bridges from Ethernet to 3.5.-micro controllers allow multiplexing multiple sensors to Ethernet (example).

To watch for inexpensive wireless Google Open Source ZigBee.

Power Consumption Measurements

Acquired Data

3.1.-Home Energy Tables

Other Home Data Acquisition

Temperature Data

Thermal (temperature, humidity, and wind) data can be used to calibrate a thermal model of your home or office. A thermal model uses multiple temperature sensors around your home to estimate thermal flow through the building. Thermal flow can be due to conduction (versus insulation), infra-red radiation (versus radiant heat barriers), and convection or mass transfer (versus air leaks and ventilation). Comfort is a function of both temperature and humidity. By tracking both temperature and humidity, it is hoped to be possible to separate mass transfer from other heat transfer types.

The following are temperature sensors I've worked with:
  • Oregon Scientific Weather station
  • Thermocron
  • Hobo data loggers
  • Thermistor multiplexing (thermistors are the most inexpensive temperatue measurement device per measurement point)

Health Data

3.8.-Health Data

3.4.-How Much Help are Proprietary Mass Market Measurement Devices

Direct Use of Solar Energy

Solar pumps

Small fountain pumps

$10-$20 at swap meets. Often work fine directly connected to small solar panels.

Solar Hot Tub Pump

I purchase a solar hot tub kit from ABC Solar. While this kit works great in the summer, it doesn't work at all in the winter. This is due to a mismatch between the voltage and current characteristics of the solar panel versus the pump. See 3.6.-Solar Pump Control for the electrical engineering challenges.

Part Source Lists

Not really wish lists: