Living off the mains gas grid, heating with LPG is expensive. Twice
the price, if I've read this table correctly: http://www.nottenergy.com/energy-costs-comparison3

We've done all we can with insulation, but the current double glazing
on the windows is old and incredibly thin (4mm or something).Last
winter, the snow remained on the roof all the way through until the
melt, but the velux windows were melted off in about an hour!

We had a quote from a local manufacturer, and actually, it's not as
bad as I thought it would be.
This is for replacing the glass into the current, sound, traditionally
shaped wood frames, including curves at the tops (so glass needs to be
shaped)
I've turned his paper "pick and mix" quote and u-values into a
spreadsheet for my own info - does all this look right?

https://spreadsheets.google.com/ccc?...Sz7wL&hl=en_GB

In particular, note the decreases in u-values regarding the filler gas
vs the increase in price. Is it actually worth going for Krypton?

We're hoping to get a fair bit of passive solar gain through the south
facing patio doors and windows.

The company come well recommended locally and by neighbours, and to be
honest, the bloke doing the quote was so pleasant and un-pushy, if you
think this looks fair I don't think I'll even bother with a second
quote.
The last time I got a glazing quote at my old house, it was a
thoroughly unpleasant and pushy experience and came to a stupidly high
price so I didn't bother.

Anyway, whaddya reckon? Do my sums make sense? Googling around here
and elsewhere seems to show that having a gas fill is definitely
noticeably worth it, but would you bother with the krypton?

Thank you.

On May 9, 8:42*am, lardconcepts wrote:
Living off the mains gas grid, heating with LPG is expensive. Twice
the price, if I've read this table correctly:http://www.nottenergy.com/energy-costs-comparison3

We've done all we can with insulation, but the current double glazing
on the windows is old and incredibly thin (4mm or something).Last
winter, the snow remained on the roof all the way through until the
melt, but the velux windows were melted off in about an hour!

We had a quote from a local manufacturer, and actually, it's not as
bad as I thought it would be.
This is for replacing the glass into the current, sound, traditionally
shaped wood frames, including curves at the tops (so glass needs to be
shaped)
I've turned his paper "pick and mix" quote and u-values into a
spreadsheet for my own info - does all this look right?

https://spreadsheets.google.com/ccc?...9WLU5IbkJHNjVG....

In particular, note the decreases in u-values regarding the filler gas
vs the increase in price. Is it actually worth going for Krypton?

We're hoping to get a fair bit of passive solar gain through the south
facing patio doors and windows.

The company come well recommended locally and by neighbours, and to be
honest, the bloke doing the quote was so pleasant and un-pushy, if you
think this looks fair I don't think I'll even bother with a second
quote.
The last time I got a glazing quote at my old house, it was a
thoroughly unpleasant and pushy experience and came to a stupidly high
price so I didn't bother.

Anyway, whaddya reckon? Do my sums make sense? Googling around here
and elsewhere seems to show that having a gas fill is definitely
noticeably worth it, but would you bother with the krypton?

Thank you.

Gas fills are used to improve the u values when new, what they don't
mention is the gas then leaks out, and performance deteriorates. You'd
get the same gain when new by adding a secondary glazing pane to your
existing dg, the 2 differences are that the insulation gain would be
permanent rather than temporary, and it would cost less. If you added
a clear plastic film on the window side of this new glass pane, spaced
off it, you'd have quadruple glazing, with even better gain.


NT

On May 9, 10:24*am, John Rumm wrote:

Its a payback trade off question really. If you assume the average
temperature differential across the window is 10 degrees. You have not
specified the total window area, but for the sake of argument, lets say
it amounts to 20m^2 for all of them. The difference between u values of
2.1 and 1.4 would translate into difference in rate of heat loss of 2.1
x 20 x 10 - 1.4 x 20 x 10 = 140W, or energy loss of 3.36kw/h per day. So
at 8.45p per kw/h that amounts to 28p/day. If you are paying that for
120 days a year, then about £33/year. That would mean a 20 year payback
(ignoring loss of interest on the money or cost of borrowing - whichever
is appropriate) on the extra cost moving from air to krypton (assuming
the units stay sealed for that long). Although you can factor in a
better comfort level with the better u Values.

etc. Wow - I'm incredibly impressed at this answer. Wish I could rate
it!
That's really given me something to chew on, some questions to ask of
the company... oh, and thanks for the DIY FAQ link too (now
bookmarked).

(It's good to see people still using calculations in working things
out - I was watching a thread on a forum about solar PV and feed in
tariffs, and it seems that actually thinking and calculating when it
comes to micro-generation is actively discouraged.)

On May 9, 10:19 am, Tabby wrote:

Gas fills are used to improve the u values when new, what they don't
mention is the gas then leaks out, and performance deteriorates. You'd
get the same gain when new by adding a secondary glazing pane to your
existing dg, the 2 differences are that the insulation gain would be
permanent rather than temporary, and it would cost less. If you added
a clear plastic film on the window side of this new glass pane, spaced
off it, you'd have quadruple glazing, with even better gain.


Hi Tabby,

a good thought, but due to the shape of the existing windows,
secondary glazing has been ruled out as awkward.
Plus the fact that a fair few of the original units are leaky and
clouded up means it's probably time to make the change.
But the plastic film idea sounds interesting, must look into (or
through!) that.

lardconcepts wrote:

etc. Wow - I'm incredibly impressed at this answer. Wish I could rate
it!
That's really given me something to chew on, some questions to ask of
the company... oh, and thanks for the DIY FAQ link too (now
bookmarked).

(It's good to see people still using calculations in working things
out - I was watching a thread on a forum about solar PV and feed in
tariffs, and it seems that actually thinking and calculating when it
comes to micro-generation is actively discouraged.)

Do the calculations, and you'll find out *why* it's discouraged.

I was over at the Centre For Alternative Technology a while back,
admiring their 10Kw PV roof. So I plugged in some optimistic figures and
came up with about 50p/ KwH, if I ignored the cost of running the
battery bank they use it to keep charged, and assumed mortgage interest
rates over a 25 year life.
--
Tciao for Now!

John.

On May 9, 4:56*pm, lardconcepts wrote:
On May 9, 10:24*am, John Rumm wrote:

Its a payback trade off question really. If you assume the average
temperature differential across the window is 10 degrees. You have not
specified the total window area, but for the sake of argument, lets say
it amounts to 20m^2 for all of them. The difference between u values of
2.1 and 1.4 would translate into difference in rate of heat loss of 2.1
x 20 x 10 - 1.4 x 20 x 10 = 140W, or energy loss of 3.36kw/h per day. So
at 8.45p per kw/h that amounts to 28p/day. If you are paying that for
120 days a year, then about £33/year. That would mean a 20 year payback
(ignoring loss of interest on the money or cost of borrowing - whichever
is appropriate) on the extra cost moving from air to krypton (assuming
the units stay sealed for that long). Although you can factor in a
better comfort level with the better u Values.

etc. Wow - I'm incredibly impressed at this answer. Wish I could rate
it!
That's really given me something to chew on, some questions to ask of
the company... oh, and thanks for the DIY FAQ link too (now
bookmarked).

(It's good to see people still using calculations in working things
out - I was watching a thread on a forum about solar PV and feed in
tariffs, and it seems that actually thinking and calculating when it
comes to micro-generation is actively discouraged.)

On May 9, 10:19 am, Tabby wrote:

Gas fills are used to improve the u values when new, what they don't
mention is the gas then leaks out, and performance deteriorates. You'd
get the same gain when new by adding a secondary glazing pane to your
existing dg, the 2 differences are that the insulation gain would be
permanent rather than temporary, and it would cost less. If you added
a clear plastic film on the window side of this new glass pane, spaced
off it, you'd have quadruple glazing, with even better gain.

Hi Tabby,

a good thought, but due to the shape of the existing windows,
secondary glazing has been ruled out as awkward.
Plus the fact that a fair few of the original units are leaky and
clouded up means it's probably time to make the change.
But the plastic film idea sounds interesting, must look into (or
through!) that.

Plastic film has limited life, but is exceptionally cheap and easy to
fit, and on secondary glazing is well protected. Payback is good as
long as its not trapping water on wood, leading to rot. Do you want to
post pics of one or more of your windows, as there arent many that
cant be secondaried one way or another.

Clouded units: fwiw some people have managed to drill them to clear
them. If you're due to dispose of them anyway, there's little to lose.
Drilled dg works fine afterwards, and your new ones will also mist up
at some point in time, so its not as if new ones are a permanent fix.


NT

On May 9, 10:24*am, John Rumm wrote:
On 09/05/2011 08:42, lardconcepts wrote:



Living off the mains gas grid, heating with LPG is expensive. Twice
the price, if I've read this table correctly:http://www.nottenergy.com/energy-costs-comparison3

We've done all we can with insulation, but the current double glazing
on the windows is old and incredibly thin (4mm or something).Last
winter, the snow remained on the roof all the way through until the
melt, but the velux windows were melted off in about an hour!

We had a quote from a local manufacturer, and actually, it's not as
bad as I thought it would be.
This is for replacing the glass into the current, sound, traditionally
shaped wood frames, including curves at the tops (so glass needs to be
shaped)
I've turned his paper "pick and mix" quote and u-values into a
spreadsheet for my own info - does all this look right?

https://spreadsheets.google.com/ccc?...9WLU5IbkJHNjVG....

The numbers look plausible. If you compare to some of the figures shown
he

http://wiki.diyfaq.org.uk/index.php?title=Heat_loss

Low E glass and argon fill seem comparable... Krypton looks like its
better still.

In particular, note the decreases in u-values regarding the filler gas
vs the increase in price. Is it actually worth going for Krypton?

Its a payback trade off question really. If you assume the average
temperature differential across the window is 10 degrees. You have not
specified the total window area, but for the sake of argument, lets say
it amounts to 20m^2 for all of them. The difference between u values of
2.1 and 1.4 would translate into difference in rate of heat loss of 2.1
x 20 x 10 - 1.4 x 20 x 10 = 140W, or energy loss of 3.36kw/h per day. So
at 8.45p per kw/h that amounts to 28p/day. If you are paying that for
120 days a year, then about £33/year. That would mean a 20 year payback
(ignoring loss of interest on the money or cost of borrowing - whichever
is appropriate) on the extra cost moving from air to krypton (assuming
the units stay sealed for that long). Although you can factor in a
better comfort level with the better u Values.

We're hoping to get a fair bit of passive solar gain through the south
facing patio doors and windows.

Most of the solar gain is via radiation, so the reduced conduction
losses that the gas change brings. Have minimal effect on this. However
the use of Low E glass (as is common these days) will reduce
transmissive gains a little. It also reduces light transmission a
little, which may mean needing more energy input from lighting for some
of the year.

The company come well recommended locally and by neighbours, and to be
honest, the bloke doing the quote was so pleasant and un-pushy, if you
think this looks fair I don't think I'll even bother with a second
quote.
The last time I got a glazing quote at my old house, it was a
thoroughly unpleasant and pushy experience and came to a stupidly high
price so I didn't bother.

Anyway, whaddya reckon? Do my sums make sense? Googling around here
and elsewhere seems to show that having a gas fill is definitely
noticeably worth it, but would you bother with the krypton?

Argon would give you a 60W reduction in losses based on the above
numbers. So the payback sums are cost neutral really.

Might be worth doing some more detailed estimates of window area. Also
ask the supplier what the life expectancy of the krypton filled units are..

--
Cheers,

John.

This, and perhaps more later, would make a great wiki article


NT

lardconcepts wrote:
On May 9, 10:24 am, John Rumm wrote:

Its a payback trade off question really. If you assume the average
temperature differential across the window is 10 degrees. You have not
specified the total window area, but for the sake of argument, lets say
it amounts to 20m^2 for all of them. The difference between u values of
2.1 and 1.4 would translate into difference in rate of heat loss of 2.1
x 20 x 10 - 1.4 x 20 x 10 = 140W, or energy loss of 3.36kw/h per day. So
at 8.45p per kw/h that amounts to 28p/day. If you are paying that for
120 days a year, then about £33/year. That would mean a 20 year payback
(ignoring loss of interest on the money or cost of borrowing - whichever
is appropriate) on the extra cost moving from air to krypton (assuming
the units stay sealed for that long). Although you can factor in a
better comfort level with the better u Values.

etc. Wow - I'm incredibly impressed at this answer. Wish I could rate
it!
That's really given me something to chew on, some questions to ask of
the company... oh, and thanks for the DIY FAQ link too (now
bookmarked).

(It's good to see people still using calculations in working things
out - I was watching a thread on a forum about solar PV and feed in
tariffs, and it seems that actually thinking and calculating when it
comes to micro-generation is actively discouraged.)

On May 9, 10:19 am, Tabby wrote:

Gas fills are used to improve the u values when new, what they don't
mention is the gas then leaks out, and performance deteriorates. You'd
get the same gain when new by adding a secondary glazing pane to your
existing dg, the 2 differences are that the insulation gain would be
permanent rather than temporary, and it would cost less. If you added
a clear plastic film on the window side of this new glass pane, spaced
off it, you'd have quadruple glazing, with even better gain.


Hi Tabby,

a good thought, but due to the shape of the existing windows,
secondary glazing has been ruled out as awkward.
Plus the fact that a fair few of the original units are leaky and
clouded up means it's probably time to make the change.
But the plastic film idea sounds interesting, must look into (or
through!) that.

In all cases heavy interlined curtains can up to halve the heatloss when
drawn closed.Not cheap, but they look good! the better the draught seal
the better they work.

There was a reasons for all those tapestries on stone castle walls you know!

The Natural Philosopher wrote:


In all cases heavy interlined curtains can up to halve the heatloss when
drawn closed.Not cheap, but they look good! the better the draught seal
the better they work.

For our metal-framed patio door, SWMBO made up some curtains with
triple linings, including one 'thermal' lining. With draught excluders
at the bottom and taking care to arrange it so there were no gaps,
most of the temperature drop was across the curtains!

If the OP has windows with a proper cill, put a draught excluder in
place every time they are drawn, that can make a big difference too.
Ditto draught excluders on the internal doors. Find where any draughts
are coming from and stop them.

Cold spots in rooms can be evened out by placing a small fan under a
radiator running on slow speed - it makes a real difference to the
comfort level and may mean the room stat could be turned down.

TF

On May 9, 5:21*pm, Tabby wrote:

Clouded units: fwiw some people have managed to drill them to clear
them. If you're due to dispose of them anyway, there's little to lose.
Drilled dg works fine afterwards, and your new ones will also mist up
at some point in time, so its not as if new ones are a permanent fix.

Replying to several posts and comments at once here, but starting with
Tabby's pic request:

Here's how thin the patio door currently is: http://goo.gl/7nTK6
And here's how foggy the fogged up old glazing with 5mm gaps which
makes up most of the rest of the windows are. http://goo.gl/PKh9R

Since making the first post, I found a couple of things out, the first
of which has made me have a major rethink about the whole thing. The
guarantee on the sealed units, ie, the double glazing that goes inside
my frames, is 1 year. Which is about 9 years less than I was
expecting! I'll probably get the worst two units done.

Also, I asked about Kyrpton vs Argon, and also Planitherm, which was
mentioned but not quoted for. When I googled it, it seems that
Planitherm is actually better than Pikington K.

The reply from the company is:
"The thing to remember is Krypton is more efficient the narrower the
airspace where as argon works the opposite way. We can do planitherm
which is the same price".

So should I forget about the Pilkington and go for the Planitherm?

One thing I maybe should mention is that it gets cold where we are in
Wales. Very, very cold. Like, -16c last winter. And for 3 days
running, the accurate, well-placed outdoor thermometer never
registered a daytime high of less than -6c for 3 days running. So,
factoring LPG too (twice the price), every therm/kW counts!

On May 11, 6:59*pm, lardconcepts wrote:
On May 9, 5:21*pm, Tabby wrote:

Clouded units: fwiw some people have managed to drill them to clear
them. If you're due to dispose of them anyway, there's little to lose.
Drilled dg works fine afterwards, and your new ones will also mist up
at some point in time, so its not as if new ones are a permanent fix.

Replying to several posts and comments at once here, but starting with
Tabby's pic request:

Here's how thin the patio door currently is:http://goo.gl/7nTK6

I'm not seeing a problem there

And here's how foggy the fogged up old glazing with 5mm gaps which
makes up most of the rest of the windows are.http://goo.gl/PKh9R

Since making the first post, I found a couple of things out, the first
of which has made me have a major rethink about the whole thing. The
guarantee on the sealed units, ie, the double glazing that goes inside
my frames, is 1 year. Which is about 9 years less than I was
expecting! I'll probably get the worst two units done.

Also, I asked about Kyrpton vs Argon, and also Planitherm, which was
mentioned but not quoted for. When I googled it, it seems that
Planitherm is actually better than Pikington K.

The reply from the company is:
"The thing to remember is Krypton is more efficient the narrower the
airspace where as argon works the opposite way. We can do planitherm
which is the same price".

So should I forget about the Pilkington and go for the Planitherm?

One thing I maybe should mention is that it gets cold where we are in
Wales. Very, very cold. Like, -16c last winter. And for 3 days
running, the accurate, well-placed outdoor thermometer never
registered a daytime high of less than -6c for 3 days running. So,
factoring LPG too (twice the price), every therm/kW counts!

Seems to me the whole gas thing is just another game. Coatings are
good in principle, but not really worth t in practice when you can go
to triple glazing for less cost. Glass is cheap, and not many windows
have no way to put openable secondary glazing on. And that doesnt lose
its value.


NT

"Tabby" wrote in message
...


Seems to me the whole gas thing is just another game. Coatings are
good in principle, but not really worth t in practice when you can go
to triple glazing for less cost. Glass is cheap, and not many windows
have no way to put openable secondary glazing on. And that doesnt lose
its value.

You can always fit some shutters, they can have insulating values several
times what glass has.
Even curtains can have better insulting values than glass so fit liners and
curtains before wasting money on argon, etc.

A few more multi-replies here, and thanks to all:

On May 11, 8:09*pm, John Rumm wrote:

If you repeat the sums I did with more accurate area measurements, you
could perhaps allow a higher temperature differential for some parts of
the year as well. Slap the figures in a spreadsheet and see how they
work out.

I think this is the way forward. It's a lot of cash (for us), and it's
not quite as straightforward as it seems, specially with the short
guarantee.
I'll let you know what I come up with.

On May 12, 12:12 am, Tabby wrote:
Here's how thin the patio door currently is:http://goo.gl/7nTK6

I'm not seeing a problem there

The gap is 3-4mm, WAY too small, no?

On May 12, 9:34 am, "dennis@home" wrote:

You can always fit some shutters, they can have insulating values several
times what glass has.
Even curtains can have better insulting values than glass so fit liners and
curtains before wasting money on argon, etc.

Hmm, but they're windows. For letting light in and looking out of.
Good heavy curtains are drawn at night anyway, it's really the day we
need to reduce the losses.

On May 12, 6:57*pm, lardconcepts wrote:
A few more multi-replies here, and thanks to all:
On May 11, 8:09*pm, John Rumm wrote:

If you repeat the sums I did with more accurate area measurements, you
could perhaps allow a higher temperature differential for some parts of
the year as well. Slap the figures in a spreadsheet and see how they
work out.

I think this is the way forward. It's a lot of cash (for us), and it's
not quite as straightforward as it seems, specially with the short
guarantee.
I'll let you know what I come up with.

On May 12, 12:12 am, Tabby wrote:

Here's how thin the patio door currently is:http://goo.gl/7nTK6

I'm not seeing a problem there

The gap is 3-4mm, WAY too small, no?

It sure doesnt look that small in the pic, but even if it is I dont
see any justification for replacing teh healthy ones. DG replacement
just isnt worth the cost on energy saving grounds.


On May 12, 9:34 am, "dennis@home" wrote:

You can always fit some shutters, they can have insulating values several
times what glass has.
Even curtains can have better insulting values than glass so fit liners and
curtains before wasting money on argon, etc.

Hmm, but they're windows. For letting light in and looking out of.
Good heavy curtains are drawn at night anyway, it's really the day we
need to reduce the losses.

day and night really.


NT