Posts tagged savings
Is a 24hr energy consumption graph really useful?
May 28th
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. 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.
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.
How to save energy through lighting control with home automation
Apr 9th
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.


