Calculating Home Energy Use

[Jean-Marc Bouvier]

I am trying to correctly determine the energy use with the metered readings of a home. Is there someone that can help me?

[Ruairi]

Hi

If you are just trying to convert meter readings to Energy use/ CO2 emission/cost, this can be done with a pen and paper and PE/C02/cost factors.  These can be got form your utility company, Defra or SAP 2009 tables. Or there is a handy research tool called I-Measure produced by Oxford Uni

http://www.imeasure.org.uk/

Set up a free account. Then you enter your meter readings weekly on-line and it records them and present them in handy CO2/energy/cost graphs

If you are trying to predict/compare energy use without meter readings you will need some modeling of the building performance done.  Simplest way to do this would be T-zero, though not very accurate:

http://www.tzero.org.uk/

Then you have SAP (standard dwelling assessment procedure)
Then for low energy buildings the best thing to use is PHPP (passivhaus planning package)

At there are plenty more… All depends what you are trying to achieve


R

[Jean-Marc Bouvier]

Hi Ruairi

Thanks for the links. What I have to hand is the total litre amount of oil used (heating & hot water) and the total amount electricity used for 1 year. Can these numbers be put in the imeasure calculator? I am trying to determine the kWh/m2/yr usage as well as the carbon factor of the home for the year for comparison to benchmarks as well as CLP and CSH levels to see where I am. Is this doable using the links you provided or is it best to use pencil and paper?

[Ruairi]

This is probably what you need so:

http://www.nef.org.uk/greencompany/co2calculator.htm

Or pen and paper

[Jean-Marc Bouvier]

Ruairi

Are these numbers correct for 1 year usage?
Oil (heating/hot water) 671L@10.27kWh/L=6891kWh
Electricity 4457 kWh
LPG (cooking) 50kg@12.5kWh/L=625kWh
Total  11,973kWh
House 302m2
Heating load (assuming 75% of 6891kwh) 17.11kWh/m2/yr
Total Energy Usage 39.65kWh/m2/yr
Carbon Factor 13.84kgCO2/m2/yr or 1.1tonnesCO2/m2/yr

[Jean-Marc Bouvier]

Hi Ruairi
Thank you very much for the link to the NEF site, it is a great tool. And I thank you again for your help.

[Ruairi]

No problem, glad it was useful

[David OLIVIER]

Sounds a very low consumption to me. Probably either very thermally-efficient - or cold.

I don't think a litre of LPG contains 12 kWh, it's nearer 7.1

There are lots of CO2 emissions coefficients around. SAP2009 seems the most reliable semi-official database. GEMIS is panm European and gives higher figures generally.


D

[Jean-Marc Bouvier]

Hi David
Thank you for the kWh for the LPG.
The house is efficient and I have another that is 418m2 and used 16108kWh of electricity for 12 months plus 50kg of LPG for cooking. The heat/hot water source is an air-to-water heat pump (11 kW).
The usage is spread over the house, stables, electric fencing, electric horse walker and work shed.
I find it hard to quantify just the house usage as there is just a single meter. Any ideas as to how to quantify the house alone and to figure out the heating load?

[Nick Grant]

Electric horse walker made me smile! From horse powered economy to economy powered horse!

[Jean-Marc Bouvier]

Does not include carrot!
Tried to have him power the house by horse!