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Meter Messenger #116 - Energy Monitors Make Great Gifts
December 15, 2011
With prices starting below $20, 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 in your computer or home entertainment system or simply measure how much energy is used to brew a pot of coffee.
Moving up to a single point monitor or an energy meter reader will allow one to monitor the entire electrical load on the 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 use awareness amongst family members.
The next grouping of energy meters we call multi-point monitors. Like single-point monitors they measure the entire load coming into the home but also have additional channels to monitor large appliance loads. These extra channels can also be used to measure energy produced from onsite generation such as solar or wind. Prices range from $250 to $750 depending upon how each is configured.
The most sophisticated type of home energy monitor is the circuit level monitor. It has the ability to monitor and track up to every circuit in the electric service panel. Power use is measured on the load side of each circuit breaker.
These systems are typically sold in modules of 12 to 16 circuits each. Modules are daisy chained together to obtain the desired coverage. Prices range from $200 to $600 per module and may require additional CT's depending upon the various circuit breaker sizes in the panel.
Keep in mind that as the price of energy monitors increases, so does the granularity of the information they provide. This finer level of detail can be used to identify many additional sources wasted energy. If this information is acted upon greater savings can be achieved.
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.
Conservation vs. RenewablesWe hear a lot of talk these days about going "Green". Underneath the "Green" umbrella there is a lot of emphasis placed upon the development of renewable energy. This got me wondering about how much of our nation's energy needs are really served by renewable energy.
Here's a chart showing the allocation of Btu's consumed in 2010 from the U.S. Energy Information Administration:
The chart shows total U.S. energy consumption in quadrillions of Btu's (the only unit of measure we use that is three orders of magnitude greater than our national debt). This includes fuel for vehicles, fuel for heating and all common forms of electrical power generation.
Notice the renewables wedge constitutes only 8% of the total energy used. It is broken out and subdivided into its own sources. Of those, conventional hydro-power and biomass constitute 84% or 6.7% (8% x 84%) of the total. This leaves wind, solar and geothermal with the remaining 16% of the renewables or 1.3% of the total energy used in the country.
Let's make a few assumptions to segregate the approximate amount of energy that is used just for electric power generation. We can strike the 37% for petroleum as most of this is used for vehicle fuel and some heating. Assume 20 of the 25% of natural gas is used for heating, as well. The remaining 5% is used in natural gas steam turbines for electricity generation. Most all coal is used for electric power generation as well as nuclear and renewables.
If we add up coal, renewables, nuclear and 5% from natural gas we can estimate 43% of the total energy consumed in the U.S. is used to generate electricity. If we revisit the renewables as a percent of energy for electric generation we find it becomes 18.6%. Within that solar, wind and geothermal constitute only 3%.
Now, let's look at the conservation side of the equation where energy monitoring is used. A study from the Florida Solar Energy Center shows that providing immediate feedback of power use can reduce residential energy consumption by 10 to 15%. Placing an energy monitor display in a prominent, high traffic area of the home is considered acceptable form of feedback according to the study.
Residential only constitutes a third of the peak demand in this country. What about commercial and industrial domains? Actually, there is even a greater opportunity for energy savings because most all of these larger accounts are billed for a demand charge in addition to an energy charge.
Think of it like a speedometer and an odometer in your car. Residential is only billed for an odometer charge in kilowatt-hours. Commercial and industrial accounts pay the odometer charge as well. In addition, they pay a speedometer charge for the highest amount of power they draw in a 15 or 30 minute period which is called demand.
Changing the time that certain devices turn on and off can have a significant impact on energy cost. The idea here is to avoid large peaks when most everything is on at the same time. Good energy monitors can alert key people as to when peak conditions are approaching so they can take appropriate action.
Feedback on the amount of energy being used is helpful in commercial and industrial settings just as with residential when trying to reduce kilowatt-hours. A TV monitor is the lunch room showing live energy consumption is a good way to increase this conservation awareness.
Conservation versus renewables - think about it. If renewables constitute only 3% of the total energy used for electric generation and good energy monitoring conservation practices can reduce consumption by 10% or more - where should we really be investing our "Green" dollars?
Illuminating Energy SavingsLighting technology is in a state of transition. The traditional incandescent bulb will begin to phase out next year. Driven by the Energy Independence and Security Act of 2007 light bulbs have to become 25% more efficient. 100 watt incandescents will be impacted in 2012, 75 watt bulbs in 2013 and 60's in 2014.
Bulbs themselves will not become illegal but replacements will no longer be available in the U.S. No need to fret as there are plenty of options - all with better efficacy.
Efficacy is simply the ratio of the lumens of light output to the watts of energy input. Better efficacy translates into lower energy cost and ultimately lower life cycle cost when bulb life is taken into consideration.
Lets look at the options. First there are quartz halogens. They draw a similar amount of power as incandescents but put out almost twice as much light. For example, a small 50 watt incandescent puts out 330 lumens while a halogen of similar wattage will produce 550 lumens of light. You won't see big energy savings on a bulb for bulb replacement unless you use a dimmer. Standard incandescent dimmers work fine with halogens.
Compact fluorescents (CFL's) deliver a marked decrease in energy consumption when compared to incandescents. A 15 watt CFL will deliver more lumens than a 65 watt incandescent when it is new, fading slightly as the bulb ages. Most have a lag time of several seconds to a couple of minutes to come to full illumination. Cooler tempertures in a garage or attic tend to extend this lag. Newer products address this by combining halogen and CFL technology into a single bulb albeit with a higher price.
A concern with CFL's is proper disposal when the bulb expires. Due to the trace levels of mercury in the bulb's chemistry they should be disposed of as hazardous waste, similar to alkaline batteries because of their cadmium. Since old habits are hard to break, many CFL's will follow the same path as an expired incandescent - into the trash and into the landfill. Over time this may become an environmental issue.
LED bulbs do not have these environmental concerns, offer excellent energy savings and extremely long bulb life. However, they are expensive. Bulb costs start around $20 each and go up from there. Prices have come down over the past couple years and are expected to do so in the future.
When we look at the life cycle cost of the bulb, LED's come out the winner when installed in lighting fixtures that receive a lot of use. Kitchens, family rooms and home offices are the best rooms to start with. The high bulb cost is offset with the extremely long bulb life (20,000+ hours) and you reap the benefit of very low energy cost.
For a detailed comparison of incandescents, halogens, CFL's and LED's please visit our new Incandescent Lighting Comparison page. We walk you through how to evaluate the different bulbs based on energy usage, bulb life, replacement frequency and cost. Links are provided to recommended products.
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. Prices start around $30.
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. If building or remodeling be sure to use insulation contact (IC rated) recessed light fixtures. A lot of warm air can escape into a cold attic if there has to be an inch or two gap in the insulation around the fixtures. IC rated light fixtures also add a layer of fire protection in the advent of a sloppy installation.
5. Always evaluate large appliance purchases based on life cycle cost - not just purchase price. Life cycle cost includes the purchase price but also looks at operating cost (energy & maintenance) over the life of the unit.
6. Put cell phone and other portable electronic equipment chargers on a power strip. Once the units are charged shut off the power strip. It keeps chargers and cords from getting tangled or misplaced and stops the trickle of wasted power.
7. High performance windows have a minimum of two panes with an evacuated space between them. In colder climates look for lower U-factor (insulation) ratings and in warmer climates look for lower SHGC (solar heat gain coefficient). In temperate climates that heat and cool look for low ratings on both.
8. If your family uses a lot of hot water consider installing a drain water heat recovery system. It extracts heat from water going down the drain uses it to preheat fresh water entering the hot water heater. Click here for more details.
9. If you live in a warm climate with a long cooling season consider a heat pump water heater. It uses the same refrigeration technology as a regular heat pump. Energy cost is about a third of that required by resistive heat but there are some caveats to consider...
10. If you have a heat pump do not set back your thermostat more than a couple of degrees at night. With most systems, if the thermostat asks for more than a two degree increase in the morning, the supplemental heat strips are energized. They typically draw three to five times as much power as the compressor pump.
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