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Exposed perimeter - Definition?

engrish?

Hey,

I'm doing the course at the moment and the notes are terrible. Its like someones drunken rambleings with no index etc, there is nothing to consult to confirm your queries.

I keep coming accross areas where I am unsure as to what the correct method to use is and I cant find anything definite in the notes to confirm against.

Exposed Perimiter when it comes to semi detached houses in the floors section of Building Elements. Can someone give me a definition of this? I downloaded the DEAP manual but I cant find the definition in this either. Is the exposed perimiter the floor area below exposed walls (ie all but that next to a heated area) or is it the entire floor perimiter.

I assume it is the "exposed" area but I cant be sure as my notes give no definition.

Thanks for your help, I just want to make sure I'm actually learning here....

if anyone has other notes they could send me I would really appreciate it.

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Jimbo

Exposed perimeter is the perimeter of the floor from which there would be heat loss.
So, in the case of a semi-d, you do not include the length of party wall.

Let me know by pm which company your doing the course with, I'll send you on info if its not the same.

engrish?

jimbo78 wrote: »

Exposed perimeter is the perimeter of the floor from which there would be heat loss.
So, in the case of a semi-d, you do not include the length of party wall.

Let me know by pm which company your doing the course with, I'll send you on info if its not the same.

Cheers for that. PM sent.

engrish?

Unfortunately we received the same notes. Does anyone have clear notes that explain what is to be inputted into the DEAP software?

dunie001

pm me if you need notes...i may be able to help.

The exposed perimeter = the perimeter (length) of the vertical part of the ground floor that abuts onto the exterior exposed walls...
_______________________________________________________

Example 1: Detached 2 story house with all exterior walls fully exposed.

Dimensions tab:
Ground floor area = 10m x 10m = 100m2.
First Floor area = 10 x 10 = 100m2

Building Elements tab (Floor):
Exposed Perimeter of house = 10m + 10m + 10m + 10m = 40m
Exposed Floor area = 100m2 (ground floor only)

___________________________________________________________

Example 2: Semi-Detached 2 story house with three exterior walls exposed.

If you then take another house of same size that is semi-detached with a party wall with a house beside it, then the exposed perimeter and floor areas would be entered into DEAP as follows:

Dimensions tab:
Ground Floor Area = 100m2
First Floor Area = 100m2

Building Elements tab (floor):
Exposed Perimeter of house = 10m+10m+10m = 30m
Exposed Floor area of house = 100m2

engrish?

dunie001 wrote: »

pm me if you need notes...i may be able to help.

The exposed perimeter = the perimeter (length) of the vertical part of the ground floor that abuts onto the exterior exposed walls...
_______________________________________________________

Example 1: Detached 2 story house with all exterior walls fully exposed.

Dimensions tab:
Ground floor area = 10m x 10m = 100m2.
First Floor area = 10 x 10 = 100m2

Building Elements tab (Floor):
Exposed Perimeter of house = 10m + 10m + 10m + 10m = 40m
Exposed Floor area = 100m2 (ground floor only)

___________________________________________________________

Example 2: Semi-Detached 2 story house with three exterior walls exposed.

If you then take another house of same size that is semi-detached with a party wall with a house beside it, then the exposed perimeter and floor areas would be entered into DEAP as follows:

Dimensions tab:
Ground Floor Area = 100m2
First Floor Area = 100m2

Building Elements tab (floor):
Exposed Perimeter of house = 10m+10m+10m = 30m
Exposed Floor area of house = 100m2

PM sent!

Mellor

Im, not trying to be rude, but if you can't manage the exposed perimeter, then you're in trouble for the rest

dunie001

a very good point...;);):D

MEONLY

I have a 2 storey with the front ground floor height only having an earth embankment.
Retaining wall 300mm,cavity 200mm, inner leaf 100mm. Cavity filled insulation with internal dry lining. Both ends & back elev as normal 2 storey.
Never had this before, I'm not sure how to treat this embankment area re heat loss etc.

Ground floor 2.5m down. Exposed/semi?
Ajacent to heated/unheated space?
All help much appreciated
Thanks in advance

MEONLY

Sorry posted the same twice

dunie001

I have a 2 storey with the front ground floor height only having an earth embankment.
Retaining wall 300mm,cavity 200mm, inner leaf 100mm. Cavity filled insulation with internal dry lining. Both ends & back elev as normal 2 storey.
Never had this before, I'm not sure how to treat this embankment area re heat loss etc.

You have to treat the embankment as "unfrozen ground" like as if it was a floor but it isn't...so this is the list you need to work out for the U-Value...

Unfrozen ground (resistance of 2.0)
External surface (resistance of 0.04)
Retaining wall
Insulation
inner wall
Timber/air cavity (air cavity resistance 0.18)
Plasterboard
Plaster (gypsum)

You have to work out the two paths for heat to travel...i.e. through timber of drylining and through the air cavity of the drylining. which invloves working out the upper resistance and lower resistances for both.

To do this you have to work out the fractional area of air vs. timber...

Say timber = 75mm x 50mm @ 400c/c (with 50mm edge touching inner block)
Fractional area of timber = 50/400 = 0.125
Fractional area of air = 1-0.125 = 0.875.

For the method to work this out, go to pg 36 in 2007 TGD Part L (on your computer) It is the formula for a roof but can be applied to anything...

If you need more help, pm me with your email address and I will help.

MEONLY

Ground floor 2.5m down. Exposed/semi?

Thanks dunie.
Am I correct in judging that the embankment length is counted as semi exposed, due to being underground?

dunie001

Ground floor 2.5m down. Exposed/semi?

Thanks dunie.
Am I correct in judging that the embankment length is counted as semi exposed, due to being underground?

Semi-exposed to what????

The wall is directly exposed to the ground...how on earth could it be semi-exposed???

The only circumstances where something would be semi-exposed would be something like a wall seperating a dwelling from a garage. which is semi-exposed because the garage is protecting the wall from the elements...

Can you understand what I posted above in my last post or do you need more details/help???

MEONLY

dunie001 wrote: »

Semi-exposed to what????

The wall is directly exposed to the ground...how on earth could it be semi-exposed???

The only circumstances where something would be semi-exposed would be something like a wall seperating a dwelling from a garage. which is semi-exposed because the garage is protecting the wall from the elements...

Can you understand what I posted above in my last post or do you need more details/help???

Thanks dunnie.
Somebody confused me with a discussion re geothermal issues and heat at that depth etc. We saw house on TV with entire area covered by earth except front area facing south etc.
Understand fully your previous post. Many thanks also.

lottyprop

A couple of questions here -

What if there is a draft lobby ? does the exposed perimeter run inside or outside of it?

What if there is a small unheated porch (not enough to be considered a draft lobby) does the exposed perimeter run behind this ?

dunie001

What if there is a draft lobby ? does the exposed perimeter run inside or outside of it?

In general the floor area under building elements and hence the exposed perimeter only includes the heated area of the dwelling. So any areas that are not heated are measure up as far as the internal face of the element that is seperating it from the heated areas.

1. Porches:

should be included if they are heated by fixed heating devices;

should be included if there is direct access into the dwelling but no separating door, whether heated or not;

should not be included if they are unheated and there is a separating door into the dwelling. In this context ‘porch’ means an addition protruding from the line of the external wall of the dwelling; an entrance lobby that is within such line should be included.[FONT=&quot][/FONT]

What if there is a small unheated porch (not enough to be considered a draft lobby) does the exposed perimeter run behind this ?

Answer: yes. because it is unheated.

joebre

Have variation of exposed perimeter question.

House has unheated garage on gable. How is the length of floor that adjoins the garage taken into account ?

Joe

dunie001

I was just wondering the same thing myself yesterday.

I presume you take the perimeter that is attached to exposed/semi-exposed elements and not to any walls that are attached to heated areas (other houses)

After all you're only supposed to take into account the areas that are heated and ignore the areas that are unheated.

MEONLY

joebre wrote: »

Have variation of exposed perimeter question.

House has unheated garage on gable. How is the length of floor that adjoins the garage taken into account ?

Joe

Measure the lenght of the wall attached to the garage and the height of it and thats your area. (Don't forget thermal envelope, storey height)
Enter this as a seperate wall area into deap. Remember to subtract this area from the overall wall area of the house. You effectively treat it as another small wall.
The area you have is now the semi-exposed area.
Look these up in your TGD or the Deap manual also gives them, with drawings. Section Heat losses 3.3/3.3.1. Apply the relevant formula for your situation.
I presume its an existing dwelling your dealing with.
The area of the garage is ignored as it is an unheated space.
Hope this helps

dunie001

MEONLY...

He was asking about how to deal with the floor perimeter that is along the bottom of the wall, not the wall between the dwelling and the garage...just to clarify.:D

MEONLY

dunie001 wrote: »

MEONLY...

He was asking about how to deal with the floor perimeter that is along the bottom of the wall, not the wall between the dwelling and the garage...just to clarify.:D

I should have added that the perimeter area only in question is regarded as being so small, (less than 10% of overall I think) that it is ignored and only the wall area calculated as my above post. I think the same may also apply to the wall area if it is small.
The idea being that the different U-Values involved would make no significant difference to the overall building.
IMO that this thinking applies to other areas in houses also in certain circumstances.
This is what I was led to believe anyway.
Now that I've written it I see why I should have explained it in above post.
I'm subject to correction if somebody has another explanation.

paddythedan

Mellor wrote: »

Im, not trying to be rude, but if you can't manage the exposed perimeter, then you're in trouble for the rest

it is rude, trying to be smart, some people have trouble with smaller areas, and others are better at complex things. isnt that why geeks find it hard to get laid, whereas dum jocks have no problems?

edit:

have a 2 month ban for dragging up a old thread for the sole purpose of insulting another poster

sydthebeat