Formulas!

For all discussion of Component Familes (eg 3D familes, 2D detail familes, annotation families, etc) and also In-Place Families

Formulas!

Postby James » Wed Jul 06, 2011 8:00 am

Anyone have any good knowledge on this?

I am going to attempt to make a formula within revit for average daylight calculation.
Last edited by James on Wed Jul 06, 2011 1:43 pm, edited 1 time in total.
Plowman Craven aim to be at the forefront of technology, especially within the BIM environment.
James
Regular
 
Posts: 112
Joined: Thu Jan 21, 2010 12:40 pm
Location: UK - Northants / Beds

Re: Formulas!

Postby Revit Zone » Wed Jul 06, 2011 10:55 am

This is an area of revit I have been meaning to develop for some time.

The basics are quite simple. All you need to do is create parameters to hold the values you need and also create parmeters to hold the answers. Then just use standard "programming" operators (ie +. -. *, /, =) to perform the forumala. When you come to create your "answer" parameter- just choose "forumla" instead of an absolute value.

I don't mind taking a look at this with you, if you want to keep this thread going- we can share some knowledge here, that may be usedful to others?

Cheers,
Ian
The Complete Beginner’s Guide to Autodesk Revit Architecture (FREE 84 part online video Course)
A complete 84 part written / video Course, aimed at Beginners. For the course itinerary and details of how to enrol, click the title link above.
Revit Zone
Site Admin
 
Posts: 638
Joined: Mon Jan 18, 2010 10:28 pm
Location: West Midlands, United Kingdom

Re: Formulas!

Postby James » Wed Jul 06, 2011 12:44 pm

that sounds great, I have roughly worked out how to pull the information from the model but im already hitting a problem

W = glazing - see problem below
A = thought of using a formula for either ceiling area and room area, or room area *2 then for the walls using the perimeter from room area * storey height
R = constant for most cases
T = constant for most cases
u = constant for most cases
M = constant

note about constants, they can just be changed on the fly, or within a parameter for the window family.


Glazing!

It seems that Revit is taking the area for glass/glazing from all sides, so it is well over.


This is the equation


DF = MWuT/A(1 – R2)


Where:

W = total glazed area of windows or roof lights
A = total area of all the room surfaces (ceiling, floor, walls and windows)
R = area-weighted average reflectance of the room surfaces
M = a correction factor for dirt
T = glass transmission factor
u = angle of visible sky

Guide values for a typical dwelling with light-coloured walls are as follows (for more accurate values, refer to CIBSE Lighting Guide 10):

R = 0.5
M = 1.0 (vertical glazing that can be cleaned easily)
0.8 (sloping glazing)
0.7 (horizontal glazing)

T = 0.7 (double glazing)
0.6 (double glazing with low emissivity coating)
0.6 (triple glazing)


u = 65˚ (vertical glazing)
Plowman Craven aim to be at the forefront of technology, especially within the BIM environment.
James
Regular
 
Posts: 112
Joined: Thu Jan 21, 2010 12:40 pm
Location: UK - Northants / Beds

Re: Formulas!

Postby Revit Zone » Wed Jul 06, 2011 1:29 pm

How are you getting the area of glazing, James? (are you taking a "material take-off" from the glass?)

What if you just took the width and height of the window and then deducted the frame area- using the parameters from the window family?

Cheers,
Ian
The Complete Beginner’s Guide to Autodesk Revit Architecture (FREE 84 part online video Course)
A complete 84 part written / video Course, aimed at Beginners. For the course itinerary and details of how to enrol, click the title link above.
Revit Zone
Site Admin
 
Posts: 638
Joined: Mon Jan 18, 2010 10:28 pm
Location: West Midlands, United Kingdom

Re: Formulas!

Postby James » Wed Jul 06, 2011 1:32 pm

yeah, I was using material take off for Glass. Which is taking all faces for it. This is where i thought of painting one side of the glass and using this for the area.

Could look at deducting the frame from the window and getting it that way, but im unsure if Revit is using the same method for the frame material.

Must be an easy way of doing it! :)
Plowman Craven aim to be at the forefront of technology, especially within the BIM environment.
James
Regular
 
Posts: 112
Joined: Thu Jan 21, 2010 12:40 pm
Location: UK - Northants / Beds

Re: Formulas!

Postby Revit Zone » Wed Jul 06, 2011 1:52 pm

W=width of window opening
H=Height of window opening
FW=Frame width (when viewing "face on")

Area of glass=(w x H)-(2*(W-(2xFW)*FW))-(2*(H*FW))

Or something like that!

Does this help????

Cheers,
Ian
The Complete Beginner’s Guide to Autodesk Revit Architecture (FREE 84 part online video Course)
A complete 84 part written / video Course, aimed at Beginners. For the course itinerary and details of how to enrol, click the title link above.
Revit Zone
Site Admin
 
Posts: 638
Joined: Mon Jan 18, 2010 10:28 pm
Location: West Midlands, United Kingdom

Re: Formulas!

Postby James » Wed Jul 06, 2011 2:55 pm

wow :D

will give it a try, but the frame varies whether its opening or fixed.
Plowman Craven aim to be at the forefront of technology, especially within the BIM environment.
James
Regular
 
Posts: 112
Joined: Thu Jan 21, 2010 12:40 pm
Location: UK - Northants / Beds

Re: Formulas!

Postby Revit Zone » Mon Aug 22, 2011 3:13 pm

Hi James :)

How did you get on with this one????
The Complete Beginner’s Guide to Autodesk Revit Architecture (FREE 84 part online video Course)
A complete 84 part written / video Course, aimed at Beginners. For the course itinerary and details of how to enrol, click the title link above.
Revit Zone
Site Admin
 
Posts: 638
Joined: Mon Jan 18, 2010 10:28 pm
Location: West Midlands, United Kingdom


Return to Family creation & editing

Who is online

Users browsing this forum: No registered users and 1 guest

cron