I want a conservatory with all glazed sides, but a tiled roof with
rooflights. Also there will be no door to the house, only an opening.

This will not be a conservatory for buildng regs purposes, but an
extension.

Now, how to I get the conservatory to pass part L (conservation of fuel
and power) when the area of openings (windows and rooflights) is
greater than 25% of the new floor?

Can I compensate for thermal losses by improving other parts of the
house? Or will a SAP calculation be required

Cheers
dg

dg wrote:

Now, how to I get the conservatory to pass part L (conservation of fuel
and power) when the area of openings (windows and rooflights) is
greater than 25% of the new floor?

Judging by most of the stories of conservatory construction I hear, the
answer would typically be "by not submitting any kind of building
notice!" ;-)

--
Cheers,

John.

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You will have to have a door.

Peter Crosland

On 4 Aug 2005 15:30:45 -0700, a particular chimpanzee named "dg"
randomly hit the keyboard and produced:

I want a conservatory with all glazed sides, but a tiled roof with
rooflights. Also there will be no door to the house, only an opening.

Now, how to I get the conservatory to pass part L (conservation of fuel
and power) when the area of openings (windows and rooflights) is
greater than 25% of the new floor?

If this extension is being built against an existing wall with windows
or doors in, these can be discounted (as the heat that would have been
lost through them now goes into the extension). If these were
single-glazed, then they can count against a proportionally larger
area of 'new' glazing (i.e., if you originally had 1m² of single
glazing at 4.8W/m²K, you could discount 2.4m² of glazing with a
U-value of 2.0W/m²K).

You can calculate the amount of glazing for the whole house. If it's
all low-e glass (with a U-value of 2.0W/m²K) and less than 25% of the
floor area, then this will be sufficient. If the existing glazing has
a higher average U-value, then the permissible area should be reduced
proportionally.

If this doesn't work, or you're not quite there, you can increase the
insulation in the walls, roof or floors. This is unlikely to
compensate for the amount of glazing alone, as practically speaking,
the U-values can only be lowered by one or two decimal points compared
to the 1.65W/K difference between a square metre of wall and a window.
Talk to your BCO. It's likely that additional measures elsewhere will
help, such as increasing the amount of insulation in your existing
loft, etc.
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have you strayed?"

On Fri, 5 Aug 2005 07:52:38 +0100, "Peter Crosland"
wrote:

You will have to have a door.

However, the hinges could mysteriously break at a later date and the
doors removed for repair...

sponix

Can I compensate for thermal losses by improving other parts of the
house?

IANAL.

Fundamentally yes, you can. It took a rather messy and complicated court
case to establish, though. Eventually, the homeowner technically lost the
appeal against a decision to not grant an exemption for a similar open plan
conservatory because the court believed that it was already compliant, so an
exemption couldn't be granted!

However, it would be quite difficult to comply. Such an open conservatory
would have considerable heat loss, which will need a lot of compensation
elsewhere. You'll need to install wall and loads of loft insulation if you
want to bring down the losses to below the level it was before the
extension. You may get resistance from the building control department.
However, the tiled roof will help you, as you can stuff loads of insulation
in there.

Christian.

On 4 Aug 2005 15:30:45 -0700, "dg" wrote:

I want a conservatory with all glazed sides, but a tiled roof with
rooflights. Also there will be no door to the house, only an opening.

This will not be a conservatory for buildng regs purposes, but an
extension.

Now, how to I get the conservatory to pass part L (conservation of fuel
and power) when the area of openings (windows and rooflights) is
greater than 25% of the new floor?

Can I compensate for thermal losses by improving other parts of the
house? Or will a SAP calculation be required

Cheers
dg

"it's not a conservatory, It's a Greenhouse....."

In article .com, Dg
wrote:
I want a conservatory with all glazed sides, but a tiled roof with
rooflights. Also there will be no door to the house, only an opening.

This will not be a conservatory for buildng regs purposes, but an
extension.

Now, how to I get the conservatory to pass part L (conservation of
fuel and power) when the area of openings (windows and rooflights) is
greater than 25% of the new floor?

Can I compensate for thermal losses by improving other parts of the
house? Or will a SAP calculation be required

A common strategy in cases like this is to provide calculations showing
the SAP Rating of the house 'as is' and as proposed, compliance being
established if the proposed rating is no worse than the existing. This
allows you to provide additional energy saving measures elsewhere to
compensate for the extension excess heat loss. Check with your BCO to
see whether he will accept this before doing all the calculations.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm
[Latest version QSEDBUK 1.10 released 4 April 2005]