
In [an earlier post](posts/2010-05-is-a-24hr-energy-consumption-graph-really-useful/) 
I discussed the utility (or otherwise) of the 24 hour power consumption
graph and questioned why Google and Microsoft were both investing in
this approach to home energy efficiency. Since then both Google and
Microsoft have stopped their efforts in this area.

Interestingly, in Europe I'm seeing more and more homes with devices
like the one shown here that provide real-time power consumption
information. One of the more interesting uses for devices like these is
as a check that everything has been turned off when a homeowner is about
to leave the house. A quick glance at the meter can reveal if a heater
has been left on in a bedroom. Of course the main water heater has the
largest impact on the reading but homeowners learn what numbers
represent 'normal' and can see at a glance when something else has been
left on. Clearly a true smart home that can turn devices off when they
are no longer in use is still a better long-term solution for this
scenario but it's interesting to see how a fairly simple device can at
least provide an indication that everything is off without a significant
investment in replacing light switches and device controllers. What
would be nicer however would be if the meter included some kind of
machine learning so it could show at a glance if the home is in a
minimal power state or not.


Home power meters revisited


[![Home Energy Consumption
Chart](/images/uploads/2010/05/HomeEnergyConsumption-300x225.png "Home Energy Consumption Chart")](/images/uploads/2010/05/HomeEnergyConsumption.png)

I'm somewhat surprised to see how much effort and excitement Google and
Microsoft are putting into the ability to show graphs of home energy
consumption minute-by-minute from a smart meter. I've had that ability
in my house for several years now (not directly measured but a close
enough proxy based on knowing which devices are currently on or off).
 My conclusion after staring at the graph on and off for several years
now is that it's really not that interesting!

Here's one of my 24 hour graphs showing the peak, minimum and average
electricity consumption in five minute intervals during the day.
Fascinating huh?  So what are you going to do with it?

The fact of the matter is that you still need to take a shower and the
fridge still needs to stay cool - those peaks really aren't interesting.
If you do want to see how much energy any device is using you can get
one of the many [Wattage Monitoring
Products](http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2Fs%3Fie%3DUTF8%26x%3D0%26ref_%3Dnb%5Fsb%5Fnoss%26y%3D0%26field-keywords%3Dkill%2520a%2520watt%26url%3Dsearch-alias%253Daps&tag=abodit-20&linkCode=ur2&camp=1789&creative=390957)![](https://www.assoc-amazon.com/e/ir?t=abodit-20&l=ur2&o=1).
They can come in handy in deciding whether to replace your television
with a modern LED TV but they probably aren't going to change the way
you behave.

[![Home Automation Energy
Saving](/images/uploads/2010/01/cropped-HomeAutomationEnergySaving-300x225.jpg "Home Automation Energy Saving")](/images/uploads/2010/01/cropped-HomeAutomationEnergySaving.jpg)

It turns out that the real problem here is the base-load rather than the
occasional short-lived peak. Some of that base load is unavoidable but
one of the top controllable loads is lights that stay on for hours at a
time, so, in your quest to reduce energy consumption, start with them.
Replacing them with compact fluorescents or LED lights is an obvious
step, but not without drawbacks (lack of dimming, harsher white light,
flickering, ...).  A better solution is to have a smart home; one that
can turn lights off when people aren't in a room, or can lower the
brightness according to the time of day. That's what my home automation
system does and it has produced some fairly dramatic energy savings as a
result: over the past 5 years it now uses 40% less electricity than it
used to! Unfortunately most home automation systems aren't smart enough
to do this - they will happily plunge you into darkness because you sat
still for too long in one room. After years of refinement (both software
and hardware) my own system can now accurately assess which rooms are
occupied and very rarely does it make a mistake that results in darkness
when there should be light. As I mentioned earlier it also prolongs bulb
life by running them at less than 100% saving more energy and
dramatically reducing how often you need to go up a ladder to change
those high-up lights.

This then is really the graph you want to pay attention to and it's
something you can make yourself using the utility bills you get every
month. I also think that the energy companies could do more to promote
green-envy: simply show people how much less energy their neighbors are
using! Shame them into action. Rank them ... "you are \#1 in your street
for energy conservation". I know some places have started to do
something like this but it needs to be widespread.


Is a 24hr energy consumption graph really useful?


Over the years as I've advanced my home automation system I've gained a
good picture as to how power is used within a home and number one on the
list of energy hogs is home lighting.  Maybe in a small house this would
be different but in America houses tend to be large and they have lots
of lights and those lights are left on for long periods of time.

In addition to replacing some light bulbs with compact fluorescents and
some with LED lights (Cree LED's only since I don't like flickery-blue
light) the house also strives to shut down the lights in any area of the
home that's not occupied.  It aggressively shuts down lights in rooms
that have had no motion in them for a while and if it detects someone
leaving it looks for more opportunities to shut off lights sooner.

Another unexpected saving that you can make with home automation is to
run your incandescent lights at less than 100% brightness.  Since most
home automation controlled light switches are dimmable it's easy to set
them to come on at 90% or less.  Based on the time of day my house will
use different lighting levels - just 20% if you head to the bathroom
late at night, 60% early evening while there's still natural light and
90% for 'full-on'.  Not only does this save energy but it prolongs the
life of the light bulbs themselves dramatically.  Couple with running at
less than 100%, the soft-start that most smart light switches offer
provides less thermal shock on the filament and it runs cooler.  And
since it takes energy to make light bulbs, and it's tiresome to go
around changing them all the time, this is one saving that pays multiple
dividends.


The Blog of Ian Mercer.

Topic: energy

Home power meters revisited

Is a 24hr energy consumption graph really useful?

How to save energy through lighting control with home automation