TM52

[richarda]

Afternoon

We are experiencing different results from the TM52 calculations when running a 2013 model in IES 2014. Some TM52 criteria vary from when we originally ran it in the 2013 version. The model is a floor of residential units. Whilst the bedroom results remain consistent the living/k*****n areas are significantly better in the more recent simulation. There appears nothing immediately obvious to explain this. Has anyone else had a similar experience?

Cheers

[Complex Potential]

You know that swearing on the forums wont get your question answered any quicker, right?

[bootsam]

I'm just venturing into this calc.

I note from the IES TM52 document a statement within 2.1 Hours of Exceedence says - " It may be seen that educational NCM occupancy profiles are inappropriate due to prolonged unoccupied periods in these profiles..."

Does this mean the occ profiles for schools, colleges etc or does it mean something else. Sorry to be a pedant but I just wish to be clear. As I use NCM ocupancy for domestic dwellings etc. Thanks for any assistance.

[RossThompson87]

Hi,

To the best of my knowledge, overheating is a design issue as opposed to a compliance one. So if the client is happy with NCM profiles that is all good. If they want the building designed to a different occupancy pattern this can be agreed.

From working on TM52, I have found that some of the DSY weather files don't fit well with certain profiles i.e. all the hot days are on weekends. So a TM52 flying pass may still mean the building overheats in mild weather!

My policy is always to get a written brief at the start!

Ross

[PCully]

Hi,

I've not seen a formal statement on this but in my reading TM52 seemed to contradict itself in the question of if we should eb using annual occupancy schedules or not but it can make a big difference since the example of schools will have no occupancy over the warmest summer months.

Quite like your comment re it being design guide rather than Compliance, that's my take on it you need to assess whatever is required by the project and as far as our tools go we have added notes in the user guide simply warning to be aware of your profiles but whatever you set up in your simulation you'll get results and an analysis for it that you can use for the adaptive thermal comfort assessment. You can even do two for occupied summer and unoccupied and see how much worse the result is in that case.

Phil

[JohnLloyd]

I've also experienced differences between the IES TM52 calculations and my own. I've put this down to differences in the way IES and my own spreadsheets deal with occupancy periods and a difference between Operative temperature and Dry Resultant Temperature. It took me a little while to work out that the IES calculation uses the Operative temperature Vista variable that only pops up when you run the TM52 calc. The Operative temp will likely be different to the DRT because it uses a different air velocity (that you define in the TM52 options box).

Without being able to see 'behind the scenes' on the IES calculation makes it pretty much impossible to investigate the differences any further.

In my opinion TM52 should have been released with a calculation tool that does the analysis for you based around your own model outputs. Or at the very least they could have included an example spreadsheet calculation that would have allowed us to all validate our own tools.