My friend wants to build a new conservatory against his well insulated house 9m x 4.5m with 3 glass walls on dwarf brick walls and a sloping roof against his house.

He hopes to use it as a full time dining room, it is shaded and faces west.

I told him it will cost more to heat it for the next 25 years than it will cost to build it. Then it would likely have to be replaced anyway.

Was I right? Building costs are arround £22,000

Roof is glass too!

So you recon 2 kW, I guessed it at 3 kW needed on a cold day buy a little heat will come through the walls from the house and more through the two french doors

So how much would that cost to heat as a part of the house for 25 yrs?

With any half reasonable guess at fuel price inflation then it looks like I might be right!

What about the cost of cooling it in the summer as well.

Its a stupid thing to do but most people are so short sighted they only consider the short term cost.

Chaps I think you have got the areas wrong. I make the roof 9 X 4.5 ~ 40msq. + length of window run = 4.5 + 4.5+ 9= 18m X height of glass 1.5m (?) = 27 sq m which I reckon makes about 67 sq m all in. So add about 60% to the previous figures!!!!
Frank

I guess things might change with the new planning bill. Aren't they altering the system for getting permission for minor works on houses?

I have just spent cash on my new house bringing the living room OUT of the conservatory and thermally seperating the thing. My conservatory is a good one with everlite roof (which I would like more info on folks if you have any) but it is still freezing in there at the mo.
When you are saying 1.8 uvalue, is this for a glazed wall? Iam confused as thinking its 0.22 for a cavity wall...... confusing me is easily done btw.
As for radiator in the garden......ALL of my neigbours have those god awfull patio heaters.
Trully, conservatorys are not liked by bco's, especially when people with sap calc softwear start wanting to thermally seperate the damn things.

Could anyone out there give me some advice? I'm neither an engineer nor an architect but I've been reading this thread with interest because I am trying to figure the meaning of current BRs wrt windows and doors. I know you'll all throw up your hands in horror, but I am about to replace the french doors and windows at the rear of my house with double glazed units which, I'm afraid, will be UPVC. ... The house is neither listed nor of architectural interest but, like many thousands of others, is a small, 1980s 2-bed town house in a quiet city suburb. Because of the way the house is built the rear upstairs windows are very difficult to paint, and so have never been painted and are rotting. The french door from kitchen to garden is insecure and ill-fitting. I have fitted seconary glazing behind the wooden windows at the front of the house. My house is rare in the area in still having its original wood window frames.

The french doors and windows I am thinking of using have an overall u value of 1.8 which I understand complies with current BRs. The window company is a small family business with a good reputation and a pride in good installation - no windy gaps round the edges. They tell me that 1.8u is D rated in the new EPCs. For an extra three hundred pounds they can made the windows and doors B rated with a u value of 1.5. this, evidently is the maximum they can achieve whilst retaining the high security classification from the Police crime prevention - an important point in a city suburb.

I'd be very interested in hearing any opinions (I'm thick skinned) re the u ratings I've described. Also, what are forum people's opinions of the new EPCs which I understand will be necessary from 1st October.

Hi tony - yes, thanks for that, but it's the u-values and how important window/glazed door u-values are likely to be in the new EPCs that I'm needing feedback on. I'll probably be selling my house within five years so I'm looking not only to make my house more energy efficient and comfortable in the short term, but also more attractive to a buyer in an uncertain housing market, in the longer term. Also, I'm not in the DIY league of being able to fit doors myself. I need someone else to do it for me, sadly.

<blockquote><cite>Posted By: Tobias</cite>Hi tony - yes, thanks for that, but it's the u-values and how important window/glazed door u-values are likely to be in the new EPCs that I'm needing feedback on. I'll probably be selling my house within five years so I'm looking not only to make my house more energy efficient and comfortable in the short term, but also more attractive to a buyer in an uncertain housing market, in the longer term. Also, I'm not in the DIY league of being able to fit doors myself. I need someone else to do it for me, sadly.</blockquote>

Hi Tony,

The windows U values don't feed directly into the EPC. There are 3 values that can go into the assessment - 1) Single Glazed, 2) Double Glazed Pre-2002 3) Double Glazed - 2002 Onwards. The difference in the double glazing is that post 2002 building regs mandated all replacement windows have to be Low E units. What this means for the assessment is you get credited with a U of 4.8, 3.1 or 2.0 respectively. This was deemed accurate enough to get within 5% of what you'd get on a full SAP assessment - which would require inputting the sizes and u value and orientation of every window. (I.e. increase the cost.)

This might change in future if it becomes mandatory to stick the U value on the FENSA Certificate but there are no plans currently to do this. It is up to the energy assessor to ask for evidence of the date of the install (reciepts, guarantees, or sometimes markings on the DG units).

What might be confusing your installer is that windows also use the coloured A-G ratings like the EPC does. But they're not linked.

Simon

if you can put wood as a primary fuel, and can get it free, based on £/m2, that would be a good result, yes?

upvc... why?? Where will they go in a few years time when they've had their life? Into landfills that will be overfilled. You could go on ebay and there are some companies who could sell you the doors and windows needed double and triple glazed, and WOODEN! No excuse any more for plastic.