How to create E/T diagram in emoncms?

I am interested in creating E/T diagram from data logged into the emoncms.


What is the E/T diagram?

The ET diagram is very useful because it gives the energy usage (need) for a specific temperature, this makes it very easy to determine if there is a problem in the heating system (broken heat pump or bad heat recycling in the ventilation system, leaking hot water) and also monitor and compare energy performance compared to other buildings. 

On one axle (X) there is average outdoor temperature (°C) and on the other axle there is average energy per square meter (kWh/m2). A specific timeframe is chosen in order to give good statistic data. Maybe 5 hour interval or 24 hour interval. This depends on heating system. If accumulator tanks are used a longer interval is preferred. If direct electrical heating is used, a shorter interval works just fine. The thermal mass of the building is also important in choosing the correct measure interval.

In order to filter passive solar heating, internal loads (TV, computers, people) and such from energy consumption one can look at night time energy use vs night time outdoor temperatures. This might give the picture of heating energy need and will provide smoother data. However if a heat pump is being used and temperatures is lowered at night this might not be the correct way to go.

This diagram makes it possible to set up dynamic alarms that will send alerts if there is abnormality in energy consumption compared to the normal usage.

This diagram also makes it very easy to determine if adjustments or alterations to the building or technical installations has made positive or negative energy changes. 

My question is how to set this up in emoncms? Does anyone know how to do this?

ET diagram

Thank you kindly.

Best regards




goodfidelity's picture

Re: How to create E/T diagram in emoncms?

Is there no news on this?


I would really like to be able to monitor the E/T diagram from emoncms.


Does this require some extra module to be added to the emoncms?


This is a really useful tool for energy monitoring buildings / cooling / heating if you need to compare multiple buildings or setup alarms that will be different during different kinds of climate.



chaveiro's picture

Re: How to create E/T diagram in emoncms?

Closest you have is in visualizations menu, compare tool.

goodfidelity's picture

Re: How to create E/T diagram in emoncms?

Hi Chaveiro!


Thanks for the input. The compare tool is a good tool. But this E/T diagram is something else. It's also a standard within the Norwegian energy monitoring and building maintenance process, i don't know about the rest of EU. For example, in order to have a energymonitoring system approved by ENOVA (Norwegian goverment) for government subsidized installation it needs to have this feature.

This kind of diagrams can be very important for users of one or many buildings.

The diagram allows for alarms to be setup, that will be activated  on different conditions depending on the outdoor temperature.

And since factors like temperature, energy and building size are all there the diagram can be used to compare building performance. It is also a really useful tool to verify changes to isolation, heating systems and other technical installations.

I would really like to get this feature from the emoncms system. Is there anyone who knows how to get this feature in to the visualization part of emoncms?

I wold be glad to help defining the features of the plugin, what parameters that needs to be adjustable, and how the visualisation could be. I just don't know how to write the code.


Best regards


Eric_AMANN's picture

Re: How to create E/T diagram in emoncms?


Few month ago, I wrote an EmonCMS module doing that job.

Not sure it works with latest emoncms version ...


PS : I confirm this is a very useful tool !

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