Skip to main content
Observer Ethical awards Winners 2011

YouGen Blog

Readers' tip of the month

Posted by Cathy Debenham on 28 November 2014 at 3:04 pm

A ground source heat pump with underfloor heating provide the warmth in DeriM's new-build house which was constructed in 2008. But it's not all been a bed of roses, heat-wise. Here's what he's learned:

"Having had some fairly massive electricity bills (c.£300) in the new build house I've been looking carefully at energy consumption.  

1)  Energy company provided monitors are of some use but the recently installed Owl Insight has been much more helpful

2) Despite what the ground source heat pump company says it really seems to take quite a chunk of the power consumption

3) Architects love lots of lights.  I've found some real savings in switching out halogens for LEDs. For example the kitchen had 10 x 50w halogens now replaced with 10 x 4w LEDs and the lighting seems better!"

Photo: ISO Energy

More information about Energy Saving and Renewable Energy on YouGen.

Find an installer

Need help with any Jargon?


If you have a question about anything in the above blog, please ask it in the comments section below.

Like this blog? Keep up to date with our free monthly newsletter


3 comments - read them below or add one

Solar Wind

Solar WindComment left on: 29 November 2014 at 5:43 pm

Hi Deri,

You can get a kWh meter for £15 that fits inside your consumer unit, which may make for an easy installation. I put one in my consumer unit to measure my spare solar PV which I divert into hot water.

You may want to consider Solar PV, as even on a bright sunny day in the winter it will almost run your heat pump for free. I was getting 2kW for a few hours today and that would certainly help offset your electricity bill.

I average 10kW a day over the year from a 4kW system saving £400+ off my bill, and getting £1,600.00 back in feed in tarrif.

Regards, Trader9.



report abuse


DeriMComment left on: 29 November 2014 at 5:22 pm

Hi Robert,

Thanks for your comment.  I have recently purchased a hard-wired meter to go on the heat pump.  The Owl Intuition has been very handy for seeing when the heat-pump is running, as you get minute by minute usage graphs, and has given a good basis for tweaking the heat-pump and underfloor heating to try to use less electricity.  As the weather cooled down this autumn it was very noticeable that the compressor on the heat pump was coming on for sometimes 11 hours straight.  Given the compressor uses around 2kWh this was making quite a contribution to my consumption.

Yes, the £300 is per month sadly.  It's actually pretty hard to get the house to use under 40 kWh per day even when it's just idling almost entirely down to the ground source heat pump.

It's a pretty big house 3000 sq ft (ish) but is built to a good insulation spec.  

Recently I have tried to improve the efficiency taking the following steps:

1) Putting Perko self closers on exterior doors (or doors going out to porches) to try to keep heat in

2) I borrowed an infrared camera and checked the whole house out.  Insulation, windows and doors were near enough doing what they were supposed to but the underfloor heating was a mess with very uneven flow through the house and fairly random heat distribution (zones upstairs on full flow and rooms too hot; zones far away from the manifold with a lot of exterior surfaces on low and too cold).  I've not looked at the underfloor heating set-up much since it was installed but having evened out the temperature distibutions (quite fidly as the flow is adjusted using an allen key on the manifold and there are no flow readings on this make of manifold) qualitatively the compressor on the heat pump seems to be running a significantly less and I've been able to drop the "indoor room temp" setting by 2 degrees and maintain confort in the house (in fact it's probably more comfortable).



report abuse


RobertPalgraveComment left on: 28 November 2014 at 6:17 pm



have you considered getting a separate hard-wired meter on the supply to the heat pump? That would give you exact consumption figures. More reliably than a clip on device. I had a meter provided with my ASHP at very low cost (during installation), and am tracking consumption with regular meter readings. That way I can better assess what proprotion of my total bill is due to heating and compare it with other uses. And with my previous oil bills.

Also, you say a 'fairly massive' electrcity bill of £300. For a month I'd agree, for a year I'd say not too bad. What period is this over?

And if the GSHP company said consumption would not be 'a chunk' they were misleading. Unless you have a passive house or one much better than Part L building Regs, or a tiny place, your space /water heating demand will dwarf other consumption. Even supplied by a heat pump with a good COP, you must be using multiple thousand units in electricity for heating.


report abuse

Leave a comment

You must log in to make a comment. If you haven't already registered, please sign up as a company or an individual, then come back and have your say.