Following previous message "Central Heating Design - Help Please", can
anyone comment on U Values for the following features please?
I have two sources of reference, the Screwfix site and Plumbing and Heating
These seem to conflict and, when I research other sources, I find these
don't tally with either of the above. Is there a definitive source for this
information? If so can someone please confirm or revise the following
feature values for me (W/m2 Deg C)?
External Wall - 11" brick-block cavity uninsulated. 1
Internal Wall - plaster, 4.5" brick, plaster 2.2
Plasterboard, 2" eggcrate cavity, plasterboard 2 (guessed)
External Wall - 11" brick-block cavity insulated. 0.7
Ground Floor - Solid Concrete
Int Floors - Floorboard, 8" joist, Plasterboard 1.7
(heat flow up)
Int Floors - Floorboard, 8" joist, Plasterboard 1.5
(heat flow down)
Pitched with felt - 100mm insulation
Pitched with felt - 50mm insulation
Flat roof - no insulation
DG Windows/doors uPVC
Thanks again for all help given previously
On Wed, 27 Oct 2004 13:16:32 +0100, "TheScullster"
<phil-at-dropthespam.com> wrote:>Following previous message "Central Heating Design - Help Please", can
My table (from HVAC guide) has 0.87 for this assuming 13mm plaster
1.76 for this one
Generous, possibly a bit less
If it's aerated blocks and mineral wool slab, 0.42
You have to take external walls into account separately here.
I have tables of U values for this which are determined from the
number and lengths of external walls and their positions.
Assuming uninsulated floor, the worst case is 1.15.
Best can be as low as 0.39
You could assume the worst case for this purpose if you want.
Alternatively, if you post the relevant room wall lengths and what
joins what, I can look up the numbers for you.
Doubling the above to 0.7 would be a reasonable assumption for this.
I have 1.6
Yes for a wooden door. For a DG unit about 2.8 for standard glass, 2.1
Don't forget that the internal surfaces are not going to be that
important unless you are going to have huge temperature differences
between rooms. Heat gain and loss room to room will not usually be a
lot; so don't sweat for the last 10W.
To email, substitute .nospam with .gl
Many thanks for your time on this.
From the figures you give I am a little more reassured.
However I would appreciate it if you could look up the following:
All floors are uninsulated ie plain concrete (due to pipe leaks we even had
to lift all the original vinyl tiles!)
The basic house dimensions are:
8m square in plan with front elevation facing approx east
There is also a single storey kitchen extension to the north which has three
exposed walls - north wall 5.5m long and east/west walls 4m long.
Finally, our room is over a garage, constructed in an extension before we
bought the property. Do you know the likely floor construction for this
room bearing in mind building regs requirements and hence the likely U Value
for heat flow down from this room?
The garage ceiling has been plastered with a plaster board "return" down the
wall which adjoins the original house about 2 ft deep. Presumably the joist
cavities will have been insulated to meet regs (it certainly doesn't feel
like it as the cold weather arrives!)
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.