SAP calculations

[David WE Roberts]

We need SAP calculations for our extension - I assume because bi-folds are over 25% of new floor area.

Can anyone recommend an online firm to do these?

Cheers

Dave R

[Hugo Nebula]

Presumably you been asked to supply calculations to show that your proposed extension performs no worse than a notional extension by your Building Control section. This is shorthand for, "there's no way your extension will comply with that much glazing, but I can't come out and say it, so you have to get your own calcs to convince yourself".

If so, what they're looking for is the total additional heat loss from an excess of glazing in Watts/degree C. You can then try and offset this heat loss from elsewhere within the extension, or if not possible, elsewhere in the building (e.g., additional loft insulation, more efficient boiler, etc.).

If you know how to work out U-values (or your architect does), you shouldn't need to go to the expense of getting two SAPs ('cos that's what you'd need - one for the house + notional extension, & one for the house with improvements + proposed extension).

[David WE Roberts]

It is a standard 'jobs for the boy/girls' thing. Allegedly the person producing the report has to have a SAP accreditation specific to the type of building (commercial or residential). If the glazing is more than 25% of the new floor area BC want a SAP report - as you say this will be a list of improvements elswhere in the building to justify the amount of glass, plus a thermal gain calculation to show that in fact with that much glass the house will be a sauna on a sunny day.

Leaving aside the issue of accreditation (which sounds like a Part P kind of thing), I just don't have time to learn how to do the detailed calculations at the moment. I suspect the BCO doesn't either, and relies on the report from an accredited SAP person. Having the architect do it would not be free, anyway, and he would just offload it to someone with the accreditation and the software package and pass the charge on at cost plus.

Standard charge seems to be £150+VAT. Our BCO does them but is off on holiday for a couple of weeks and we need them soonish. Sounds a bit suspect, doesn't it? BCO says " Lot of glazing there, mate, need a SAP report. Luckily I can do one for you". However the rules seem pretty specific so it is possibly not as dodgy as it seems at first glance.

Cheers

Dave R

[Hugo Nebula]

There's a few allegations of misconduct flying around there. I hope you can substantiate them, otherwise withdraw them.

I notice that in your reply you didn't answer the question of who has asked you to produce heat loss calculations, and in particular said that you have to use an acccredited energy assessor. Has this suggestion come directly from the Local Authority Building Control in direct response to your submission of a Full Plans application?

It's not the case that if openings >25% floor area then calculations. Most BCOs will take a reasoned judgement on the areas of openings. Calculations need to be checked by the BCO on the principle of garbage in = garbage out, so they need to have some knowledgable in how to draw up emissions ratings (and how to fiddle them).

In terms of learning the calculations, if you can multiply, add and work out percentages, then you can do the most basic first part which is to check the heat loss against a notional building. If it fails this first test, then, yes, you may need to take into account the solar gain, etc.

If your BCO is asking for them as part of his plan check then offering to do them for you at a price, report him to his boss. That is a sackable offence.

[David WE Roberts]

You seem to be reading an awful lot into a few comments. Nothing stated is untrue to my knowledge, nor have I sugested that there is any misconduct.

BCO has stated that SAP calculations are required. The online SAP sites suggest the 25% glazing guideline.

"SAP Calculations are an extremely useful method of demonstrating compliance with Part L1B of Building Regulations via the Design Flexibility criterion.

This method is often used for extensions with high levels of glazing which is deemed as being excessive by Building Control (more than 25% of the extended floor area) or in cases where homeowners wish to have a conservatory or sun room open to their existing property."

" Extensions

If you build an extension where the glazing is over 25% of the floor area, then we can undertake a SAP assessment to demonstrate Part L compliance"

So given that the extension goes out 3 metres and the bifolds go up abot 2.4 metres and are across most of the rear (plus of course the three roof lights in the vaulted roof) it seems likely that SAP calculations would be required. With me so far, or is this totally wrong? The SAP calculations were requested by the BCO at the time the plans were submitted for Building Regs approval. Our architect had previously stated that SAP calculations would probably be required.

People we have spoken to, including our architect, suggest that to offer a commercial service providing SAP calculations one has to be certified - we know of one person who can't offer the service because here certification hasa recently lapsed.

Our architect mentioned that the person who was coincidentally our BCO was also certified to provide SAP calculations, and he approached him to see if he could do this for us. So happens that he is on holiday.

As I commented humourously (do you have a sense of humour?) at first sight this could seem a bit dodgy but I see no conflict of interest and neither has anyone else involved.

Why should I do the calculations if I can employ someone else? It is my judgement how best to spend my time and money - when to do something myself and when to employ someone else.

If of course you feel that any of my statements are legally actionable by all means take this further.

If not, can you just try to be helpful? Please?

Dave R

[Hugo Nebula]

If one is producing an Energy Performance Certificate in connection with a house sale, etc., then the person has to be accredited. To produce calculations to check whether your proposed extension complies, no formal registration or qualifications is necessary.

In the early days of SAP ratings (IIRC 1995 or thereabouts), I and a few colleagues went through the formal training; ostensibly to make sure we knew what we were looking at when we received SAP calcs. Due to restrictions on what work Local Government could do, Building Control wasn't allowed to carry out SAP ratings when they were legally required. As an individual, providing SAP calculations for a job I'm checking is tantamount to drawing up plans; a sackable offence.

LABC Consult (the private company owned by all local authorities) does offer SAP calcs, maybe using some LA directly-employed BCOs, but the BCO checking your plans sees none of the fees from that (except in so far as it helps to maintain the LA share of the BC work out there).

The smiley wasn't evident, and I'm not amused by the almost accepted assumption that Local Government Officers are on the take.

Shant!

[David WE Roberts]

So the BCO would be commiting a sackable offence if he took on the work.

Oh, hang on, then the BCO would NOT be commiting a sackable offence? Make your mind up!

To me, at least, you are giving a strong impression of the guilty fleeing where no man persueth. What, particularly, has made you so very sensitive to this? Personal experience of local government corruption?

[Hugo Nebula]

I have, and I have explained. A private individual employed by the LA can't; a limited company can.

Personal experience of a great many people posting on usenet of local govt corruption without evidence.

[David WE Roberts]

Just to be clear, I have not posted about local government corruption. Despite your rather extreme initial reaction.