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RE: [EnergyPlus_Support] HVAC templates and autosizing

Hi David,

I think your final question is the most important one, and should be answered first. Especially when considered on a more general level.

Yet before contemplating to build an interface to E+ / tool around E+ in the framework of the EU Energy Performance for Buildings Regulations, one should ask whether a dynamic method is the way to go here. In this context I would like to point you towards the work carried out in the EU ENPER project which deals with this issue: http://www.enper.org/pub/html_B6/ENPER_B6_final.html#long_main_full-dyn

Regarding pitfalls in constructing an interface to EnergyPlus, I have participated in a project in which we constructed an interface to E+ in order to improve the access to this tool in a design analysis context [The DAI-Initiative, for more info see e.g. : Augenbroe, G., P. de Wilde, H. J. Moon, A. Malkawi, 2004. An interoperability workbench for design analysis integration. Energy and Buildings, 36 (8), p 737-748]. I think the findings will also apply to an interface for labeling purposes.

The most important lesson from this work (from the viewpoint of E+ interfacing) is that, to obtain a really unambigous performance rating, you not only need make sure that the interface streamlines the description of the building to E+ regardless of the user's knowledge, but also the description of the "testing conditions" under which you evaluate the building (climate, occupant behavior, HVAC settings, ....), the definition the "results" to be produced by the simulation, as well as the specification of the "aggregation" of these results into very specific performance indicators. This might seem trivial but is in fact quite a hard job. Especially since you are working in the context of building regulations, which require that the modelling job (!!!) becomes reproducible. We did this through development of "templates" for analysis tasks that covered all these aspects, which were linked to E+. I think you will need something similar.

Another thing is that you will need to think about how to handle future E+ releases. As you said, the tool is expected to return the same energy 'rating' for a building regardless of the user's knowledge. For legislative purposes it will also be imperative to be able to redo your assessments years after the initial rating took place (e.g. if a rating is disputed in court). This means you will probably need labels that are linked to a version of your tool/interface and E+ engine (which seems not very desirable from a regulatory point of view?). And it is important to think of how the UK regulations will handle direct use of E+. Will it be possible for engineers to bypass your labeling tool/interface and do their own simulation? 

I hope this helps.

Best regards,


dr.ir. P.J.C.J. de Wilde
TNO Building and Construction Research
PO Box 49, 2600AA Delft, the Netherlands
phone: ++31-15-2763520
fax: ++31-2763022

> -----Original Message-----
> From: mkenergycentre [mailto:mkenergycentre@xxxxxxxxxxx]
> Sent: Friday, July 23, 2004 6:24 PM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] HVAC templates and autosizing
> Dear All,
> Some more questions, but this time about HVAC simulation. Before I 
> begin I think I should explain the reason for these questions. The UK 
> government is considering using EnergyPlus as the basis of a tool 
> that will form part of our Building Regulations, specifically to 
> enable energy labelling of buildings to comply with a new European 
> directive which will be introduced in January 2006. I (and many 
> others) are being asked to comment on the practicality of this 
> approach and, as well as the questions below, I'd be interested in 
> any other views that current users may have on this proposal. Bear in 
> mind that the tool is expected to be used by any qualified engineer 
> (not specialists) and should return the same energy 'rating' for a 
> building regardless of the user's knowledge.
> 1) I've read in a number of places that putting a system together by 
> hand in EnergyPlus can be difficult and time-consuming, but that 
> templates are much better. Is there a list of the currently available 
> templates? And which have autosizing incorporated?
> 2) How difficult is it to create a new template? For example, how 
> long did it take to create the 'Single Duct VAV w/ Reheat' template?
> 3) What skills are required to create a new template? If someone was 
> already a skilled software developer how long might it take to aquire 
> the EnergyPlus knowledge to be able to do this?
> 4) Finally, not an HVAC question, are there any users with experience 
> of creating an interface to EnergyPlus who can comment on any 
> possible pitfalls? I believe a major part of the work the UK 
> government is considering will be interface development so any 
> comments based on practical experiences would be appreciated.
> Many thanks
> David.

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