IES-VE User Forum

I am a new student user of IES VE. I am undertaking a masters thesis which involves looking at how different glazing options affect the energy use of an existing office building.

I am modelling the existing building in IES VE and intend to validate my model by comparing the simulated energy use to actual energy use as gathered from the building’s last 12 month’s utility bills.

In order to do this I think I will need a weather file of actual weather data which covers the same time period as the utility bills (June 2009-May 2010). I am trying to source this and have made contact with Met Eireann (Irish meteorological service). However, I don’t know what weather parameters to ask for and in what sequence/format they should be. Are there fixed parameters that IES VE requires? And assuming Met Eireann can give me the correct parameters in the correct sequence, presumably this will be in a spreadsheet (eg .xls) document. How can I convert this into a .fwt or .epw file?

Any help is much appreciated.

This is not a question related to IES per se, but I'll try and help anyway.

Firstly, I recommend sticking with Energy Plus format as it is standard and openable as a text-file.

Secondly, you need to familiarise yourself with weather file formats. There are standardised formats, but there are different ones in use for different countries. Read the Energy Plus manual, it quite explicitly state what is needed to build an Energy Plus weather file. I don't know what they do in Ireland, but they should be able to provide you with the standard entries required for a specific weather file, you should just need to tell them which, and if they don't know, if you specify them they should be able to do it.

Thirdly, when you do this, you'll need to ensure that there is no kink when going from May 2010 to June 2009. IESVE does preconditioning of the model (10 days by default) and it will use weather from the previous year, so you'll want to ensure that when you go through this transition period that it follows.

Fourthly, I just want to say that using just the energy bills for this is not a good idea. Utilities frequently use monthly estimates and read only every 2-4 months, meanwhile IES simulates at every hour. That's a massive time-scale difference, and when "validating" your model you won't actually know the peak heating & cooling demand nor the usage patterns. You will need to know the actual fluctuation in hourly energy consumption of the building, and to do this for a couple of non-consecutive days, otherwise the "validation of the model" just becomes "let's fiddle around with IES parameters until it kinda looks like the utility bills", and if so I can't see the use of doing validation in the first place.

Thanks a million for the feedback!

And thanks also for the comment about validation, I take your point. Energy into the building comes in the form of electricity and gas. I know that the electricity is metered at 15min intervals remotely, I can try to get hold of this information. Gas utility bills usually specify usage at an increment of every 2 weeks on average, I must see whether in reality it is being metered at smaller intervals.

Thanks again, your feedback is very useful!