Savaplug review

A comment on energy saving in the home.
"One accurate measurment is worth a thousand expert opinions", Grace Hopper

We have a 15 year old freezer and a some what older fridge. In the not to distance future they will both have to be upgraded to A+++ models. In the meantime I thought it would be a good idea to try a savaplug, from www.savawatt.com. I was not so impressed!

12 March 2007 22:10
To:enquiries@savawatt.com
Subject: Savaplug performance

Sirs,
I would be interested to know the basis of your figures for the
Savaplug. I purchased the unit from yourselves and tested it using
the Maplin Energy Monitor. Results for a Electrolux EU1320 freezer,
purchased 1992

With fitted plug, 1.23 kWh/day
with Savaplug, 1.19 kWh/day
saving 2.8% at 11.52 p/kWh, annual saving of £1.34.
This is a 15 year payback or 50% longer than the guarantee!

At 15 years old, there can not be many freezers less efficient than ours. Indeed the fridge, which is older, only consumes half a kWh
per day. I run a course on carbon reduction and energy in the home.
Can you provide any further information that would justify mentioning
the Savaplug?

Regards,

19 Mar 2007 10:09:24 +0000

Subject:
Re: Savaplug performance
From:
Andy Brown Date:
18/03/2007 16:32
Tarinderjit Lehal at SavaWatt wrote:

Thank you for your e-mail.

I apologies for the late reply, we currently moving into larger
premises which is introducing an unavoidable delay.

I would expect you would see a larger saving by using a power meter
set to instantaneous power, but if you try to measure kWh over days
it may give you a false reading. This is due to the fact that the
utilisation of the appliance will not have been taken into account
when comparing the two figures. There are also many different types
of power meters available on the market and in some cases they don't
always give the same values due to the algorithms they use to
calculate energy. For this reason I would suggest that you measure
instantaneous power in Watts to give you an indication of savings.

Also the savings achieved from the SavaPlug will depend on the type
of appliance you have and how you use it.

I hope this has been helpful.

Please contact me if you have any further enquires.

Thank you

T Lehal


19 Mar 2007 10:09:24 Andy Brown

Dear Tarinderjit,
Thank you for your reply. I am surprised by some of your comments. I would be grateful if you could you clarify the issues you have raised.

Why is instantaneous power (watts) a better measure of power saving than energy consumed (kWh, Joules)?
You suggest that a longer energy trial is needed. Is this not at odds with your suggestion that instantaneous power is a better indication of saving?
How long a trial do you suggest? What data for fluctuations in daily consumption of electricity in freezers do you have?
Given the small number of power meters on the market, I had hoped you might be able to comment on the accuracy (or even the algorithms ) of the Maplin unit that I was using.
What data do you have for comparative savings for different makes of appliance.

We have another meeting on Thursday. I hope you have time to comment before then.

Regards, Andy

I will add to this post if there is any interesting news!