QUESTION:

I've been happily learning ECOTECT over the past few weeks, but there is one thing that no one in our office is too clear on - when to run inter-zonal adjacency calcs. Can you give me a list of functions that require inter-zonal adjacencies to be run ?

In particular, we're wondering about overshadowing and solar exposure calculations. Since it takes a while to do, we'd rather skip inter-zonal adjacencies when we can.

ANSWER:

The inter-zonal adjacencies calculation is done to work out what model surfaces overlap between zones and to generate and cache the solar shading masks of all objects on thermal zones. This information is needed by thermal, acoustic and large scale solar shadowing calculations. I say large scale because the insolation on selected surfaces in the Graphical Results dialog is calculated in real-time (its only a few objects for a set time period) whereas the cumulative insolation calculation needs to cache masks because you may want to run it over many thousands of surfaces and then for lots of different time periods.

Getting used to this calculation is not as difficult as it may first appear - or should I say, you'll eventually get used to the inter-zonal requirements

Basically the general rule is, if you change the geometry you will need to run an inter-zonal calc. Now that is not when you assign a different material, it's when you physically alter the model geometry. There are exceptions of course, and to make matters worse we do try to improve this with each update so that (as you rightly mention) the process can be a quicker one. One exception that comes to mind is when you switch zones on/off. It used to be that you had to re-do the inter-zonal for that (usually in the before and after scenario of a neighbouring development for overshadowing, say), but now (v5.2+) it is not the case.

I think perhaps, the best suggestion we can make for you (other than reading through the page on inter-zonal calcs in the help) is if you are unsure just try a really simple scenario with a couple of box zones on a test model so that you can double check and be sure you are getting the change/results you anticipate before you run your main time consuming calcs. Better to know before than after you've spent the time, yes...

I know this might seem a bit odd to suggest, but to be honest I usually do this myself when I can't remember or am not convinced by results, and I guess it is a good way to build confidence in what the software is doing...

Also, ECOTECT will try to determine when a inter-zonal calc needs to be done and will prompt you as such -- but it is a dumb computer program and as the user it is always better that you know what should be happening rather than relying on it to tell you.