Therm workshop booked

sinnerboy

Therm workshop booked for wed 25th Feb at 7.00pm-8.00pm in room 329 Bolton St.(immediatly under the 2nd year Arch Tech studio)

Can hold about 18-20 students, bring laptops but note there are only a couple of power sockets.

Poster beyondpassive will present a guide through the BRE method (ward ,sanders 2007) of calculating Ψ Psi values.

Bring a laptop - download the free Therm software ( link below ) and install

Admission is free , see you there

Resources
1. methodology.
Ward, T. and Sanders, C. Conventions for calculating linear thermal transmittance and temperature factors. 2007 BRE Trust

BRE’s Information Paper IP 1/06
BS EN ISO 10211

http://products.ihs.com/cis/Doc.aspx...&DocNum=283982

2. Therm 5.2 freeware
http://windows.lbl.gov/software/therm/therm.html

user manual
http://windows.lbl.gov/software/ther...ERM52_docs.htm

setup parameters
http://www.aecb.net/PDFs/conference0...20aecb2008.ppt

topcatcbr

How do we book this

sinnerboy

Just turn up TC . Be good to meet again .

topcatcbr

sinnerboy wrote: »

Just turn up TC . Be good to meet again .

I will be there if i can make it (ill try my best) as it wasnt covered in the PHPP Course i did last year. Could be very usefull. Be good to catch up. Maybe even go for a pint after.

beyondpassive

Sorry Wednesday 24th not 25th.

sydthebeat

ill be there (ala jackson 5, circa 1970)

beyondpassive

Reminder:

Therm workshop tomorrow wed evening
have you downloaded therm 5.2.

Have your laptops charged up too, shortage of power sockets in room.

sinnerboy

Many thanks BP for a very informative presentation last night . 100%

sydthebeat

seconded, thanks BP.....

very informative..... enough information to have the confidence to play with teh tool... thanks again!!

Dabzarch

Finally get off the mark here!! As Syd and Sinnerboy said, excellent. Very useful information.

Thanks BP.

R

msft

Hi all,

I know this is a reasonaly old thread but I need help with Therm.
I did a brief intro Therm course a while back but only remember some of it.
I now have to do a psi calc for a foundation detail in a hurry.
Can you help if I explain how far I have got, and in what seuence?

I did the following: :rolleyes:
1. Underlay the drawing
2. Created drawings in Therm and assigned Materials and colours - I even added my specific materials to the library to use (added the Conductivity values but not the emissivity values!)
3. Then I clicked BC to add boundary conditions - which I did but think I might have got some wrong!
4. Clicked Calculate.

I remember something about UFactors needing to be entered - which I did nothing with.
I also remember something about a %error figure to check - I have in my notes! But cannot remember why.
I also remember I have to do something with the figure in Therm into a formula to get the psi value.

Can anyone help me - or maybe I am too far beyond help?????

beyondpassive

Hi

Sorry for late reply,

Have you resoved the geometry, are there any red circles highlighting when vectors overlap or arn't parallel.?

You can adjust the accuracy settings to tolerate gaps of about half a mill.

With therm, You need do three drawings. First the entire junction, with the length of flanking elements to suit the BRE guidance outputting the L2d figure. Then calculate u value of the wall extrusion and then the floor extrusions seperately using u-factor, and enter them into the BRE formula.

Its awkward, makes it almost worthwhile to fork out for HEAT 2D or Antherm.

Ecominded

Hi BP

Just came upon this tread today

I would appreciate if you could give further help on how to calculate L2D using Therm.

My current understanding (which is probably wrong) is when dealing with the entire junction (wall and floor) you set the u-factor tag the same for all internal boundaries and the resulting total length u-factor output multiplied by the external length is the L2D figure required.

If this is not the case I would appreciate an explanation of your understanding of the procedure for calculating L2D

Regards

beyondpassive

Ecominded

spreadsheet attached here.
http://www.peterwarm.co.uk/resources/downloads/
( Mods apologies, I'm posting this as a resource, I wouln't classify the consultant as a business in this case more an educator in this niche subject.)

Just remember, In BS 10211 there is a different formula for calculating slab on ground thermal bridges.

I'll get to this again, wrecked now. Anyone else able to help.

Ecominded

Thanks BP

I'll work through it.

Dabzarch

Ecominded wrote: »

Hi BP

Just came upon this tread today

I would appreciate if you could give further help on how to calculate L2D using Therm.

My current understanding (which is probably wrong) is when dealing with the entire junction (wall and floor) you set the u-factor tag the same for all internal boundaries and the resulting total length u-factor output multiplied by the external length is the L2D figure required.

If this is not the case I would appreciate an explanation of your understanding of the procedure for calculating L2D

Regards

Just to build on the information provided by beyondpassive.

One of the main documents you will need is BRE 497:2007 (which is based on the requirements of ISO 10211:2007). This document provides the numerical modelling conventions which need to be applied to each type of junction, i.e. roof eaves, gable, ground floor etc.

Each surface/wall is required have a surface resistance. There are three main types, upwards, horizontal and downwards.

The link provided by BP has each scenario identified and the temperature and surface resistances applied for same. set up internal and external u-factors and apply the boundary conditions to each surface. i.e. ceiling would be upwards. external wall horizontal and floor would be downwards.

Simulate and multiply the internal U-factor for both Projected X and Projected Y. (or select internal --> total length) This will give you L2D.

once you have L2D you apply it to the formula for the specific junction as provided in BRE 497

most of the junctions are straight forward once you get the hang of it. the tricky one is the ground floor. Be sure when you are doing your U-Value calculation for the ground floor it complies with ISO 13370 (this document deals with heat transfer via the ground). Or work it out as a individual (1D) plane in THERM where it will give you the U-factor. Also when calculating wall u value you should do a THERM based 1D model also as to keep the figures consistent.

That is my understanding...i am open to correction on the above.

Also ensure the setup parameters in preferences -> term file options are set up as per PW recommendations (this ensures the simulations validity with ISO 10211 requirements)

Hope that's not too confusing!

Ecominded

Thanks

That explaines it.

just one other question. when using Therm to calculate a 1D u-vlaue in a timber framed wall for example how do you allow for the 15% timber fraction, Is the only way to adjust the material thermal conductivity you input.

beyondpassive

i'd suggest working out the U-Value for the insulation and then for the timber and apply an area-weighted average to it, i.e 85% insulation 15% timber. Adjust wall U-Value to match. I wonder if you can just apply an area weighed lamda to average the insulation and timber conuctivity?

t wex

Hi
I'm wondering would you have any tips on importing dxf underlays into therm and improving results with the auto convert.

I'm drawing my walls up as polylines then saving as dxf before importing. But only the odd line comes through into therm.

Regards
Tom

Dabzarch

This is how I would approach it...

1. ensure all lines are closed polylines, ie boxes etc...

2. make sure the drawing file is saved as a autocadr12.dxf version. (it doesn't open when saved to any other dxf version for some reason)

3. start a new Therm file -> File -> Underlay -> Select file and tick autoconvert box -> press ok.

t wex

Thanks Dabzarch
I'll give that a try in the morning

t wex

Hi Dabzarch
That worked a treat, thank you.

Dabzarch

t wex wrote: »

Hi Dabzarch
That worked a treat, thank you.

No Prob.