Forum discussion

ASHREA Simulation vs. actual building operations

9

You rely on LEEDuser. Can we rely on you?

LEEDuser is supported by our premium members, not by advertisers.

Go premium for $15.95  »

Tue, 12/21/2010 - 16:54

Your question covers a lot of issues, but in general the intent of M&V is to ensure that the building is performing as projected/expected. This inherently means that there must be performance projections, usually in the form of energy simulations. (Otherwise, how do we determine which design strategies are effective and which are more in the realm of wishful thinking?) While LEED and/or ASHRAE impose certain parameters on the process of comparing the performance of a Proposed building to a baseline, the form of the Proposed building simulation for the purposes of M&V is really not constrained by these parameters. In fact, it could be argued that it shouldn't be if the primary objective is to truly validate the projected performance of the Proposed. So, while it is true that ALL energy simulation software packages suffer from limitations to varying degrees, it is usually possible to develop "workarounds" for many of the issues. Often it is simply a matter of devising creative ways to model a condition using the basic capabilities of the software e.g. scheduling ventilation to mimic DCV based on expected occupancy. At the other end of the scale it may be necessary to develop custom simulation functions or combine simulation tools, such using the output from a specialized CFD analysis to schedule space conditions in a more mainstream simulation package. And, bear in mind that many apparent software limitations turn out to be inconsequential if fully considered from a first-principles perspective - which in many instances is why the "feature" was left out of the software in the first place. While energy modeling will never be perfect, in my experience very seldom is it impossible, one way or another, to generate results that are a defensible projection of building performance. BTW, the 25% process load in LEED is only a default. You are entirely free to use a higher or lower value provided that it can be justified.

Mon, 03/21/2011 - 11:41

Looking through the IPMVP document it appears that credit EA 5.1 has nothing to do with the energy modelling required in EAP2/C1. Under option D: Calibrated Simulation, it talks about comparing a baseline energy model (which is autosized) and based on a real weather data file over the M&V period, with an 'as built' energy model with actual design capacities/values etc and then comparing the both of them to actual metered readings. Is this correct? If so, then you do not need to enter in any energy use information into the 5.1 submittal for C&S and New Construction projects because the project is not monitored yet. Is this correct? or have i missed something here? thanks in advance

Sun, 04/24/2011 - 20:09

EAc5.1 does in fact start with the energy models produced for EAp2/c1. The Proposed model as submitted for certification should represent the as-built building. The model is then calibrated through the M&V process as described in my response below to Robin Williams Heeks. With respect to providing the actual energy use as part of the EAc5.1 submission, you are correct - that is simply an error in the on-line form.

Add new comment

To post a comment, you need to register for a LEEDuser Basic membership (free) or login to your existing profile.