We have an end-of-terrace solid walled house. We are planning to start adding insulation to the interior faces of most of our external walls. We plan to hit the Energy Saving Trust's "best practice" u-values and I also fully intend to notify Building Control about our thermal upgrades. My question is this: when we come to sell the house, will the Energy Performance Certificate take into account the thermal upgrades I will do, even if we don't get round to upgrading every single external wall? For example, our house has 3 bedrooms and a living room. If the living room's external walls have a u-value of 0.30 but bedrooms are all still 2.1 then will the Energy Performance Certificate "see" the improved performance of the living room's walls? Or do I have to upgrade every external wall in the property before the EPC will register any improvement?

(We are actively researching external-wall insulation but I expect it'll be too expensive for our budget).

Many thanks,
Jack

As long as the assessor has been trained properly - they should be able to factor it in if the house isn't too complicated elsewhere. The RDSAP software allows you to record an "Alternative Wall" type - so you can specify addtional (or less) insulation compared to the main construction of the house. The conventions are that it has to be 10% of the house or more before it's included.

However - you'll have to make the assessor aware of it, as it's not always easy to spot. (If they are any good they might have a questionnaire asking you about this type of thing).

RE External wall insualtion - have a look a NBT Wood fibre insulation, carbon negative. I believe you can get training with some companies to do DIY installs - but not necessarily NBT. What I'm hoping to do is fix the insulation myself (only skills required are drilling and sticking, but with someone sticking up scaffold first) and then get a local plasterer trained up in lime so he can do the finishing. Alternative finishes of bricks slips and wood panels can also be fixed on a DIY basis.

Simon

Dan_aka_Jack: I was a bit perturbed to read that you intend to notify Building Control about your plan to install some internal insulation to your outside walls. Is this a legal requirement then, or is it something that you feel you want to do?

I'm not an expert but I think it is a legal requirement to inform your local BCO if you modify the thermal performance of more than 20% of an existing element (e.g. a wall). Building Regs specify certain requirements about retrofitting insulation (have a look at Building Regs part L B, available as a free download) But notifying the BCO does have the advantage that if your BCO knows about your insulation improvements then it's more likely that your insulation improvements will register on your building's Energy Performance Certificate when you come to sell the property (so I've been told).

I could be wrong though.

@Peter: I have no links to these companies and can't vouch for if their systems are any good...

http://www.netweber.co.uk/external-wall-insulation/how-to-apply-our-products/training-course.html
http://www.wbs-ltd.co.uk/approved_contractors.htm
http://www.natural-building.co.uk/contact_nbt.htm

I've yet to see if they'd let a DIYer on their courses but it might still be cheaper to pay full whack for a course than someone to install it. My guess is that £150 is subsidised - with the expectation you'll be giving them £100,000 a year in sales ;-)

@syd:
DEAs can't access U-Values in the UK. It's on the cards for the future - but first someone has to decide whether to let all DEAs to do it which means CPD for all, - or "specially trained" DEAs who might also be able to carry out invasive testing (drilling holes) if you request it. No planned date yet - more important stuff to sort first - 99.99% of houses don't have "special insulation" and fit in the standard RDSAP model. Things like making sure standards are being upheld and applied consistently across DEAs , estage agents complying with the regs by making EPCs available and getting people to act on the recommendations in the EPC is more important at the mo!

Simon

Posted By: Jeff BDan_aka_Jack: I was a bit perturbed to read that you intend to notify Building Control about your plan to install some internal insulation to your outside walls. Is this a legal requirement then, or is it something that you feel you want to do?

Hi Jeff, it is a legal requirement, but the triggers for upgrading are quite complicated and there are exclusions. There's a detailed explanation of the Legislation on Page 330 of Green Building Bible Vol 1. Also the latest Green Building Mag page 38
http://www.greenbuildingmagazine.co.uk/winter08/index.php

Mike/Nick/Dan_aka_Jack: many thanks for your responses. Unfortunately I don't have the latest edition of the Green Building Bible. However I will try to get a copy of the latest Green Building mag. My plan is to affix 50 mm of Celotex insulation to the upstairs bedrooms walls/skeilings in my dormer bungalow, then cover over with plasterboard. There is already some Celotex behind the dwarf walls and the skeilings (75 mm), so I am effectively going to improve the insulation. I just find it incredible that I might have to pay £75 for the privilege of informing some bureaucrat that I have improved the level of insulation in my property! Why should I need approval for this? Is this why I have never read any mention of this on this forum – shades of “ignorance is bliss” perhaps?

Bu we are all supportive of the 'Insulate, insulate, insulate' mantra, aren't we? And it's plain from a lot of the threads that many would wish to achieve insulation standards well beyond Part L. I agree that if I know I've achieved the standard anyway I don't actually need a piece of paper to prove it, but I do think we should be supporting and advertising the existence of a law which effectively says 'in these circumstances, when you think building work, you must think energy too'. I agree with you, Mike, that there is little knowledge or policing (and that the cost is irritating), but if the imposition will result in a few more houses getting somewhere near the levels of insulation that we need to achieve, then is it not (part of) a good thing? I imagine it's going to ease the sale of houses as well, not only in terms of a better EPC score, but because mopre q's seem to be getting asked about whether such-and-such work had Bldg Regs approval.

Mike - thanks for your last response. Sorry for the delay in replying. I have a copy of the 3rd edition of the GBB (but not the latest edition). I have looked this up and I presume the section you are referring is your article on pages 144 - 146. So, if I can show that the U value of the existing dwarf walls/skeilings is already 0.35 or less, then I presume I am exempt from the requirement to inform the BCO about putting in additional insulation? Is it possible to have an informal chat to a local BCO before deciding what to do?

On a more general, philosophical note, I fail to see how the requirement to contact the BCO (and pay a fee as well!) will act as an incentive to any green-minded DIY-er who wants to improve the energy conservation of their property by increasing the amount of insulation anywhere in the property. No wonder we see nothing about this subject on the forum! Surely any improvement has to be a good thing? Sorry, I don’t mean to shoot the messenger here, but this all reminds me a bit of the ludicrous situation whereby one can be held liable for any person injuring themselves by slipping on partially cleared ice/snow on one’s driveway but not liable if no attempt has been made to clear the ice/snow in the first place!

Dan aka Jack: I take your point about resale values. This may be highly relevant in your case but I should point out that we moved in here about 18 months ago and this is intended to be our retirement home i.e. the only way we plan to move out again is in a long wooden box as my grandfather used to say, so the issue of resale value is not such a major concern to us (our kids may think differently of course!). We are trying to be as “green” as possible, having already removed the existing oil fired combi-boiler and installed a wood pellet boiler, four solar FP collectors and a thermal store. For sure, in the not too distant future the number one question from prospective house buyers will be “what does it cost to heat the place?” I cringe when I very occasionally watch those TV programmes about couples who have xxx pounds to spend on a property and invariably seem to end up buying some rambling old place in the countryside without energy costs even getting a mention. Surely such places will become un-saleable in the future unless they plough a heck of a lot of their cash into energy conservation rather than by adding a conservatory and extending the patio with another half an acre of decking, patio heaters etc.?

Jeff, sorry I am not Mike, but:
'' I have a copy of the 3rd edition of the GBB (but not the latest edition). I have looked this up and I presume the section you are referring is your article on pages 144 - 146. So, if I can show that the U value of the existing dwarf walls/skeilings is already 0.35 or less, then I presume I am exempt from the requirement to inform the BCO about putting in additional insulation? Is it possible to have an informal chat to a local BCO before deciding what to do?''

Yes, I believe that to be the case. If you comply already you don't need to get official confirmation that your works will more than comply! And yes, BCO may have a chat first.

You say, re obligation to get BC approval, '' No wonder we see nothing about this subject on the forum!'' Not nothing, I have been plugging away at it on various threads for a while! ''Surely any improvement has to be a good thing? ''. Well yes and no. I did my solid-walled house 20+ years ago to u=0.5ish. I **wish** I had done better. The labour would have cost no more, and the materials a relatively small percentage. But if it's any compensation, some BCOs have a problem with it too!

batkinson, can you please clarify? You seem to say something different to my understanding. Do I understand right that, if you are renovating more than 25% of a wall, for example, with an exg u value of 0.33, aimimg for, say, massive improvements in air-tightness and u=0.2, say, you have an obligation to obtain Bldg Regs approval?

renovating more than 25% of a thermal element triggers the requirement to obtain building regulations approval.
If you intend to do something better than the minimum standard recommended by building regulations you still need to obtain consent

Jeff B. I share your confusion. I believe that part L1B makes the assumption that you are starting from a lower level. I find it hard to believe that BC should insist on being involved if you already complied, and simply wished to do better than 'merely' complying. *Why?* batkinson, can you enlighten us?

dan_aka_jack,

In answer to your op, photograph the works as you go along, make sure you use at least 50m of insulation, and present the photos to the DEA when he or she carries out the energy assessment. There is a field for Internal Wall Insulation on the field sheets, which should be ticked.

Cheers.........

Yes, but surely if that thermal element already meets the minimum threshold value [ie 0.35W/m2K for ceilings],then there is no requirement to better it, and therefore no need to notify building control? What would be the point of notification?