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Meter Messenger #128 - Energy Monitors Make Great Gifts
November 15, 2013

Issue #128
November-December 2013

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Table of Contents

Energy Monitors Make Great Gifts

Solar Stirling Engine Project

Home Energy Management Integration

Ten Energy Saving Tips

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Energy Monitors Make Great Gifts

Not sure what to get that special person this holiday season. Consider an energy monitor - a unique gift that it is not only educational and fun to use but can actually save money on your electric bill. Simple plug-in meters start as low as $20. Please visit our Energy Monitor Store where you can choose from over two dozen different models.

A simple plug-in meter is a great buy for someone just getting started with energy measurement. It can be used as a stand-alone device that can measure any 120 volt plug load. Use it to identify vampire loads associated with your computer or home entertainment system or simply measure how much energy is used to operate your refrigerator.

Moving up to a single point monitor or an energy meter reader will allow one to monitor the entire electrical load on their home. Prices for these units tend to fall in the $100 to $175 range. Remote displays can be placed in high traffic areas of the home to increase energy awareness amongst family members.

Multi-point monitors allow you to measure the entire load coming into the home but have additional channels to monitor large appliance loads such as the air conditioner, hot water heater or clothes dryer. These extra channels can also be used to measure energy generated by solar panels or wind turbines. Prices range from $250 to $750 depending upon how each system is configured.

At the top of home energy monitor line is the circuit level monitor. It has the ability to monitor and track up to every circuit in the electric service panel. Power is measured on the load side of each circuit breaker and tracked through online software that can give you information about your home energy use anytime anywhere. It can even control your thermostat remotely and text you alerts when preset conditions are met. Prices start around $500.

Keep in mind that as the price of energy monitors increases, so does the granularity of the information it provides. Putting this information to good use can increase the amount of energy dollars saved making the payback period for more expensive models on par with lower priced models.

As a guideline for pricing whole house energy monitoring systems we recommend capping your budget at twice the amount of your average monthly electric bill. This way, with a modest savings of 8-10%, you will recover your investment within two years.



Solar Stirling Engine Project

Recently, while perusing some alternative energy technologies, I came across a solar efficiency conversion rate of about 30 percent for a something called a solar Stirling engine. Knowing solar PV panels deliver around 10-12 percent, the 30 percent statistic caught my eye because it meant this device could deliver three times the energy for the same amount of solar exposure.

Basically, the device uses a parabolic mirror to capture and concentrate the sun's energy on a combustion plate to power the Stirling engine which drives an alternator or DC motor to produce electricity. The Stirling engine was invented back in 1816 by Robert Stirling and operates on the principle of cyclic compression and expansion of a gas at different temperature levels which converts heat energy to mechanical work. Click here for a working diagram.

It is an external combustion engine because the heat source resides outside the walls of the cylinder(s) as opposed to an internal combustion engine where heat is generated inside the walls of the cylinder through the burning of fuel such as an automobile engine. Using a parabolic mirror to concentrate solar heat on the head of the hot cylinder provides the energy needed to power the Stirling engine. A solar tracking mechanism is needed to keep the parabolic mirror pointed directly at the sun for maximum efficiency.

There are some commercial units working at remote military installations and at universities doing solar energy research but appear to be very expensive if purchased directly. However, there are some DIY units that can be built at reasonable cost if you are the type of person inclined to tackle an interesting project from time to time. We have added a link for an instruction manual and plans set on our Alternative Energy page.

Having just ordered the plan set, I found the drawings for the engine to be quite good, although the narrative in the manual is rather brief and there are a few typos. Instructions are provided to build a parabolic dish out of cardboard or light plywood and line it with aluminum foil. This will probably work but will not hold up to the weather over a long period of time. A preferred alternative is to use an old satellite dish and line it with small mirrors. There are no provisions for a solar tracker in the plans but many options are readily available on the Web.

The narrative assumes you have a working knowledge of how to hook up solar power using a charge controller and an AC inverter if you want to power appliances in your home. Output from the Stirling engine will drive a small DC motor which works like a generator when driven mechanically. This output will charge a 12 volt battery bank which, in turn, can feed power back into the home through an AC inverter. I don't expect to see any major changes in my electric bill as this is a small, proof of concept unit.

However, if it proves to be successful, scaling up the Stirling engine to drive a larger alternator may prove to be a viable option in the future. In either case, it should prove to be a fun and educational project to tackle. I'll share the results in a future issue of the Meter Messenger.



Home Energy Management Integration

If the recent CEDIA (Consumer Electronic Design & Installation Association) Expo in Denver is any indication, home energy management systems are becoming an integral option available through many home automation systems.

For example, Nest Labs announced a developer program that will work with other manufacturer's products through the Cloud. The first feature is the ability to see room temperature on a mobile device and have the ability to turn the thermostat up or down. This capability has been available for some time through individual manufacturer's platforms but this is the first attempt at delivering it on an open platform making it accessible across boundaries that have been proprietary in the past. Future capabilities will most likely allow some of the usage data to be shared with the Smart Grid.

Wireless Z-wave technology is being used to capture whole house energy use along side plug-in modules that capture energy consumption data from individual appliances around the home. In the past this has been done by monitoring individual circuit loads at the service panel breaker but output has not been able to differentiate between individual appliance usage on the same circuit. New apps are able to feed this information out to users through smartphones and tablets as well as schedule commands to turn things on or off or adjust dimmers in response to the information received.

Savant if offering WiFi-connected smart plugs that not only monitor the energy used by the connected devices but offer surge protection as well. This feature is offered for individual outlets or smart strips. They are also introducing an 8-zone SmartClimate system that provides temperature, set point and HVAC operational status to mobile devices.

As home automation systems continue to evolve, integrating the management of energy becomes a natural addition to deploying the technology in an efficient, cost effective manner.



Ten Energy Saving Tips

1. Consider an infrared thermal leak detector for an energy saving gift idea. It looks like a laser pistol and returns the temperature of the surface where the laser dot is aimed. Great for finding cold spots around windows or doors. Available at most home centers or click here to order on line. Prices start under $40.

2. Consider upgrading your holiday light sets to LED's. They much less apt to have to bulb outages or dead strand sections and operate on a fraction of the energy needed for conventional lights.

3. Use a timer on your holiday lights so you don't inadvertently leave them on all night. It will help ease the "sticker shock" a bit when all the holiday bills come in after the first of the year.

4. Check the ceiling of your crawl space. Is it insulated? If not, consider doing so as significant radiant heat loss can occur through the first floor. If your bedroom is on the lower level, that barefoot walk to the bathroom first thing in the morning will be a bit more pleasant.

5. Warm air rises. In high ceiling rooms keep ceiling fans circulating warm air back down into the inhabited space near the thermostat. Personal comfort increases and furnace run time decreases.

6. Keep south facing windows clean and free of obstructions during the day to maximize passive solar heat gain. Pull drapes at night to minimize heat loss, especially if windows are large.

7. Cold air can creep into your home through a variety paths; recessed lighting fixtures, sill plates, the attic entrance, door frames, electrical outlets and plumbing cutouts to name a few. Test for drafts on a windy day by tracing suspect areas with a candle. Any abnormal flicker on the flame will indicate a source of cold air entering the home. (Be careful not to catch the curtains on fire as you do this test.)

8. Building a new home next year? Consider geothermal for heating and cooling if you are in a climate that does not have extreme winters (i.e. sub-zero temps for days at a time). SEER ratings can reach into the lower thirties which is much more efficient than any compressor driven cooling system. Click Here for a great set of ideas on how to design and install a geothermal system.

9. If you have a fireplace, install glass doors. They reduce heat loss up the chimney, aid in more efficient combustion and provide a barrier to sparks.

10. Select seasoned hardwood that has moisture content around 20 percent for most efficient burning. Check for cracks in the end grain, a darker color or a hollow sound when you knock on it as telltale signs the wood is properly seasoned.



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