Elemental

The following example is one which BRE used at the recent Part L 2010 workshop I attended a few weeks ago. At the time I was mildly amused by the fact that they’d given us the example, but hadn’t worked out a solution themselves. Having been through umpteen iterations, I can see why.

I’m going to use this example as a way of demonstrating some key points with regards the new Part L, which I don’t think everyone in the industry has picked up yet. I am assuming of course that Part L 2010 will come in on 1 October. Perhaps no-one else shares my optimism and are ignoring the changes in the hope they’ll go away and die a slow death.

• Biomass is no longer the silver bullet it was under 2006
• EPC’s in 2010 are on a different scale to EPC’s in 2006, so cannot be compared easily (as we suspected – see the comments following this post in May)
• A building which had an EPC of 40 under Part L 2006, gaining an Excellent under BREEAM 2008, does not automatically pass Part L 2010
• a 25% improvement over 2006 does not automatically mean your building will pass under 2010 – the aggregate approach means there are no easy rules of thumb – and that table which I linked to in this post has disappeared
• An low EPC under Part L 2010 does not guarantee Part L compliance
• The efficiency of building services has by far the greatest effect on ratings

It has turned out to be a very long article so to read the whole thing, see under the fold. Read more…

admin Accreditation isbem, Part L, Part L 2010

So Part L AD’s did finally get released. I figure most of the readers of my blog will have noticed this. I wanted to write a full review but unfortunately we are still twiddling our thumbs waiting for supporting documentation (this sound familiar at all, or am I getting (more) cynical and grumpy in my old age?).

For those who have had trouble finding the page with the new approved documents, it can be found here. The only supporting document released so far “Non-Domestic Building Services Compliance Guide 2010 Edition” is available here. The crucial missing piece of the jigsaw is the 2010 NCM Modelling Guide, which will detail exactly how the aggregated 25% split across non-domestic buildings will work. I’m guessing the reason why cSBEM v1.4 is also not released is because the two need to be issued at the same time. I expect when the modelling guide is issued it will live on the same website as the NCM and SBEM, here.

The key change is under paragraph 4.6 in the Approved Document:

Note that the TER is no longer based on a 2002 notional building and an improvement factor; for 2010 it is based on a building of the same size and shape as the actual building, constructed to a concurrent specification. This concurrent specification for Part L 2010 is given in the 2010 NCM modelling guide. Developers are still given the freedom to vary the specification, provided the same overall level of CO2 emissions is achieved or bettered. This approach to target setting has been adopted because the level of improvement that can reasonably be expected varies significantly by building sector, and so a blanket improvement factor would be inequitable. The specification delivers an overall 25% reduction in CO2 emissions across the new-build mix for non-dwellings sector (the so-called ‘aggregate approach’). Some building types will be required to improve by more than 25%, some by less, but all should achieve the required level of improvement at approximately the same cost of carbon mitigation.

Until the NCM Modelling Guide is released, we have to second guess the aggregate approach (using the figures from the initial consultation) and hoping cSBEM is not a million miles too wrong. *Sigh*.

This throws up interesting questions for what is going to happen to EPC ratings and BREEAM ENE1 credit. Currently credits are awarded on an EPC score. The EPC score is a CO2 index (and reflects the carbon per m2). A compliant building under Part L 2010 will still have a CO2 index, presumably. But a hotel will be compliant with a CO2 index which is considerably different to a shallow plan office, for example. Will the rating bands for EPC’s need to be adjusted for different building types? And similarly for BREEAM credit ENE1?

Also where will the points be awarded for BREEAM 2010 Excellent – an EPC of 40 in 2010 will be easier to gain (as in it is closer to the pass rate) – will the goalposts move, ie an EPC of 30 or less?

I am going to a BREEAM consultation event very soon, so hope to have some answers then.

For reference, my original posts on the consultation are available: part 1, part 2 and part 3.

One of the best posts I have seen so far is this over at the IES blog – well worth checking out the pdf which shows really clearly the difference between the old notional building and the new version.

admin Regulation Part L

So the election has been called for May 6th. Despite the statutory instrument being laid down before the election was called (to allow work to continue between now and the election and prevent purdah kicking in) things are still looking very quiet over at CLG.

To alleviate the drumming of fingers on tables as we all wait with baited breath, the Consultation Responses have been released. You can read the 264 page pdf here.

I won’t go into the entire detail but pick out some interesting points re: SBEM and DSM which I have pulled out below. These points won’t make it in for 2010, but perhaps 2013 will see the demise of SBEM (we live in hope).

The SBEM calculation engine is based on a monthly energy balance that can only ever be a crude approximation to how the building performs. Yet energy assessors are required to gather large amounts of data and the proposals for Part L 2010 exacerbate this. There is a mistaken belief that adding more data and complexity will improve accuracy. There are two possible alternative options:

i. Simplify SBEM and greatly reduce the amount of data required, thereby recognising it can only ever be a simple comparison tool to allow a building’s performance to be compared with a reference building. There is much data currently required that has little effect on the rating and an aim should be to reduce the information required perhaps by 50%.

ii. Recognise that SBEM was only ever going to be a stopgap measure and encourage the development of software tools that can produce EPCs and BRUKL reports from realistic computer models that can be also be used for design. These tools could be used to realistically assess the effectiveness of improvement measures which should be the main output of the recommendation report. The recommendation report needs to be made more prominent and summary recommendations shown on the EPC.

This is an important point to remember when doing concept and initial calculations – the accuracy of the calculation needs to be appropriate to the scale of the problem. If you are trying to figure out baseline figures on figures to the nearest 5kWh/m², there’s no point in calculating to the nearest 6 decimal points. I was recently reminded of the excellent book Chaos: Making a New Science by James Gleick which makes a similar point:

The choice is always the same.  You can make your model more complex and more faithful to reality, or you can make it simpler and easier to handle.  Only the most naive scientist believes that the perfect model is the one that perfectly represents reality. Such a model would have the same drawbacks as a map as large and detailed as the city it represents, a map depicting every park, every street, every building, every tree, every pothole, every inhabitant, and every map.  Were such a map possible, its specificity would defaet its purpose: to generalise and abstract. Mapmakers highlight such features as their clients choose.  Whatever their purpose, maps and models must simplify as much as they mimic the world.

I really recommend the book – it explains the pitfalls of complexity perfectly.

This is a conversation I think we need to continue to have when it comes to BIM, SBEM and DSM in the near future. The consultation responses give me heart. Here is another point which was made:

There are reservations about the ability of SBEM to model low and zero carbon buildings in a robust manner. Dynamic simulation should be more heavily incentivised and eventually made mandatory. For example, the current SBEM software is not capable of modelling fabric designs that employ passive measures or intelligent or active facades to reduce solar gains. Indicating compliance in the software with a “yes” or “no” does not provide any guidance on how fabric performance can be improved. Experience suggests that daylight savings are much more effective in reducing CO2 emissions than marginal improvements in heat loss, especially when heat recovery is implemented, but this is not reflected in the cSBEM methodology.

Whilst I’m all in favour of using simplified tools where they are appropriate (see my point about scale above), many of the current problems with SBEM* stem from the fact that it is being substituted as a design tool rather than being used purely as a compliance tool (it’s initial purpose). We can either improve the compliance tool so it can be used for design also, or rethink the entire approach. A suite of DSM tools, with differing levels of detail seem the most logical solution to me. One model gets constantly refines throughout the work flow (in an ideal world) rather than one model being forced to do tasks it was never set up for.

Thoughts anyone?

*worth reading the whole post on Pathethic Part L

admin Opinion, Regulation CLG, Part L

Had I realised the 17th was not tomorrow, but today, I might have been able to construct a more considered piece. For completeness, here are some further rambling thoughts on the Part L 2010 consultation. Issues I wanted to look into further but ran out of time on included overheating, and a better understanding of the numbers involved in L2A vs. L2B.

Not discussed at the Sponge event, but will be of interest to some will be the proposed approach of aggregating the percentage improvement over building types (for non-domestic), rather than a flat 25% improvement over the 2002 notional building. This means that averaged over the building stock, a 25% improvement will be made. Whilst I applaud the logic, the ‘black box’ aspect of applying these curves, plus questions over what happens if the predictions are wrong (i.e. the mix of building works changes dramatically over the period of time the curves are supposed to work) mean I am not entirely happy with this. I agree it’s probably more sensible than the flat approach for non-domestic stock, but are we approaching the problem correctly in the first instance?

Are the goalposts changing? Are we still comparing to 2002 notional building? Or was the 2002 notional building never the right building to compare against in the first place? The answers are, yes, no, probably not. Part L 2010 is an improvement on 2006, but an improvement to a less than ideal solution to begin with.

There are some who think that SBEM should never have been introduced and that a DSM approach (perhaps based on the open-source US DOE program Energy Plus, which was once the basis of IES) should have been employed as the only non-domestic solution from the outset. Are SBEM’s days numbered? I’m not sure – I haven’t managed to find out figures for numbers of buildings submitted using SBEM vs. DSM over the last 4 years (I feel a request for information under FOI coming on), but I personally am much happier using proprietary DSM software than SBEM, even if the building templates have largely been slim-lined and rationalised for 2010.

Ex-colleague Lynne, over at Hattie’s blog says:

In the Part L consultation, reinforced by the Zero Carbon Definition response from government, a clear emphasis on reducing demand through building fabric is made explicit in the guidance, although as yet the proposals are not prescriptive via U-values and the principle of design freedom is maintained.

As an architect, what is clear to me is that we need to gear our design development process to understand the impacts of what we draw from day one – in Part L and F terms, this means getting orientation, fenestration, construction typology and solar access right so that we are using the ‘basics’ to minimise demand as far as possible from the very outset.

Part L 2010 still gives designers some degree of discretion, rather than dictating a ‘cookie-cutter’ solution. Simplified and arbitrary targets (and yes, I am having a dig at Passivhaus here) devalue and marginalise design engineers. We cannot allow this to happen. Defending discretionary behaviour should be the rallying call of CIBSE, IStructE and others, improving the profession’s standing in the UK (which we cannot allow to be subjugated any further).

There was a puff piece some time back in the AJ, where the Tories rather jokingly wanted to abolish Building Regulations. Let’s not throw the baby out with the bathwater, but rather than tie ourselves in knots trying to meet arbitrarily set targets, let’s get back to first principles and remember what the intentions of the Regulations are:

• conservation of fuel and power
• predicting carbon emissions and ensuring they are less than a stated minimum

It is well within our ken to apply our minds to these riddles, retaining design freedom and without getting lost in a mire of red tape. Isn’t it?

admin Regulation consultation, Part L

In the first of this series of posts, I set the background to the Part L 2010 consultation. In this post I am going to look at the issues which were raised at the recent Sponge/CIBSE consultation event , which I attended on 20 August.

Hywel Davies presented 7 issues which were of concern to CIBSE:

Part F – Ventilation. With the increasing demand for more airtight buildings, especially dwellings, the requirement for ventilation is being reviewed, the compliance guide contains installation requirements for natural and mechanically vented systems as well as an installation and commissioning checklist that should be completed as part of the installation handover and signed and approved by a person “qualified” to do so. For more information see volume 3 of the consultation

I will admit I haven’t had time to fully come to grips with Part F. The points made by Hywel were that there will be a drive towards more mech vent in homes. Whilst in principle this is not a problem, he raised some concerns regarding installation, commissioning, operating properly and maintaining correctly.

I have to concur with Hywel on this one – hand on heart – when was the last time each of you cleaned the filter/grille on your bathroom extract fan – especially anyone in rented property?

Hywel also had concerns with fuel poverty and affordable housing – there is already evidence of unauthorised interventions in the sector with regards to fans in the past.

Again, I have to concur – I had first hand experience of this in Bucks County Council in the late 90’s with whole house mech vent systems in council housing – was perceived to be a cost and so many were ‘imaginatively’ disabled.

Process energy. The proposed approved documents clarify that energy efficiency requirements apply not just to spaces providing human thermal comfort, but also to any building space where energy is used to condition the indoor climate but can the energy efficiency measures be easily applied to buildings where heating and cooling is used during a ‘process’? To read the relevant section of ADL2A start at page 111 of volume 2

 This relates to consultation Question 69: Do you agree that Part L should set standards for buildings which use energy to condition spaces that contain processes, such as computer rooms and cold stores?

Server rooms – this was a hot topic of debate on the night. Should server rooms be covered by Part L or not? As they cover process rather than comfort, one school of thought (which I would agree with) thought not, others thought they ought to be.

Part L deals with the building and fixed services. Computer server rooms consist of often changing equipment, with loads varying to meet the demands of the occupants and as such should not be treated as fixed services.

Processes such as computer rooms will be covered by CRC (for many occupants) and any future carbon tax mechanisms. As such, they should not be included in Part L (although they should indeed be incentivised to be as efficient as possible). Building Regs should stick to what they were designed for and not used as a mechanism for regulating things outside the scope of buildings.

Micro vs macro. The proposals focus on compliance for individual buildings but should there be more to promote district heating solutions? For more information see page 356 of volume 2 (non-domestic) and page 267 (domestic)

Tension between Building Regs and Planning requirements – micro vs macro. There is a gap between community/district and building solutions – again, this is something which should be anticipated for, but not led by Building Regs. i.e. do their best to avoid penalising community heating as a solution. There were a few points raised about biomass – an increasing import industry not really giving fuel security, and also pollution issues

Compliance. A theme of the consultation is closing the gap between ‘design performance’ and ‘real performance’. Some of the proposals are the Accredited Construction Details scheme, wider use of Competent Person schemes, design stage BER/TER calcs and production of a commissioning plan by the designer. What are the causes of this performance gap and are these proposals therefore what is needed to close this gap? For more information read chapter 2 of volume 1 (page 19)

The solar overheating sections of Approved Document L2A set out glazing criteria that have to be met for side lit and top lit spaces. Are the criteria reasonable? For more information see page 131 of volume 2 onwards.

The 2006 regs referred to CIBSE (which we know is subjective at best), 2010 puts in more guidance – is it sensible?

Consequential Improvements. The government has ‘ducked’ out of addressing this issue explicitly in the consultation. There are many low cost improvements that could be made to a building’s energy performance and this is a particular recommendation that CIBSE and other organizations would like to make to the CLG.

We will also be looking at the ‘future thinking’ section where CLG is asking for thoughts on Part L and what might be incorporated after 2010.

Point was made that there is a dearth of research for 2013 and 2016

Other points made during the night were surrounding the fuel factors which are still skewed towards electricity. Again, rather than ‘mask’ the high carbon in the Building Regs, if BEAMA, Creda etc want to protect the electrical heating industry, they should do so in a mechanism OUTSIDE the Building Regs – subsidise at installation/source – not muddy the compliance calculations.

There was also some degree of discontent with SBEM, with calls for it to be scrapped as it is anything but ‘simple’. A DSM approach or a return to elemental method were proposed!

Next week, I’ll mop up any loose ends and collate some conclusions. Any comments?

admin Regulation building regs, consultation, Part L

So after a fun (?) summer of consultations, the final date for submission for the Part L and F consultation will soon be upon us: 17^th September. The consultation came out on 18 June, but with a massive 800 odd pages to wade through it has taken most of the summer to digest.

This series of posts will mainly concentrate on Part L2 for non-domestic buildings, so I won’t touch on the consequential improvements debate. Plenty has already been said on this here, here and here (that last link is where the ACE have threatened to sue the government – oh to be a  feisty lobbyist!). For those who are interested in Part L1, there is a good summary over on the NHER website (pdf). There is also a very good CIBSE micro-site available which covers L1 and L2. Comments could be added to the CIBSE response up until 4^th September, so too late now. However, it is worth checking out some of the questions and answers on the forum.

There is also a good powerpoint presentation from AECOM/BRE available here (216 slides, 8MB long but useful): www.aecom.com/media/5930.pdf

I shall start with some basics, to set the scene:

The Approved Document (AD) deals with the energy efficiency requirements in the Building Regulations 2000. Historically, the AD was only a method of compliance (not a regulation). This changed in the 2006 revisions to the Building Regulations (which I will touch on below).

It is worth reminding ourselves what Part L of Schedule 1 states:

Where does our carbon obsession come in then? There is only mention of energy and fuel in Part L? This tension between energy and carbon comes up again later, so pay attention.

There are currently two separate requirements to carry out CO₂ emission rate calculations. These are under (i) regulation 17C of the Building Regulations 2000 and (ii) Regulation 17E implementing Article 7 of the Energy Performance of Buildings Directive, requiring the provision of Energy Performance Certificates. It has been proposed that these two be simplified into one regulation but has not yet happened. The ‘master’ Building Regulations document is available here (pdf). The Schedule comes at the end. So our approved document ADL2A incorporates not just Part L, but regulations 17C and 17E. Confused yet?

The AD sets out 5 criteria. If it can be demonstrated that all five have been met, then the building is compliant. Of these, the first directly relates to a regulation (17C) and is therefore mandatory. The BER must be less than the TER and either SBEM or DSM must be used to demonstrate compliance. Criterion 2 through 5 remain guidance only. The 2010 revisions to 2006 are in italics below, deletions shown in strikeout:

Criterion 1: in accordance with regulation 17C, the calculated predicted CO2 emission rate for the building as constructed (the Building Emission Rate, BER), must not be greater than the Target CO2 Emission Rate (TER)

Criterion 2: the performance of the building fabric and the heating, hot water and fixed lighting systems should achieve reasonable overall standards of energy efficiency following the procedure be no worse than the design limits set out…

Criterion 3: Those parts of demonstrate that the building that are not provided with comfort cooling systems have has appropriate passive control measures to limit solar gains. The guidance given in…; and the aim is to counter excessive internal temperature rise in summer in accommodation that does not need air conditioning and where it is not therefore provided. The impact on CO2 emissions from mechanically cooled buildings is taken into account in the BER. the purpose is to limit solar gains to reasonable levels during the summer period, in order to reduce the need for or installed capacity of air conditioning systems.

Criterion 4: the performance of the building, as built, is consistent with the prediction made in the BER…Extra credits will be given in the TER/DER calculation where builders provide robust evidence of quality assured procedures in the design and construction phases

Criterion 5: the necessary provisions for enabling energy efficient operation of the building should be put in place.

The UK’s much touted zero carbon goal was actually set in the Budget in 2008:

an ambition for all new non-domestic buildings to be zero carbon from 2019 with consultation on the timeline and its feasibility and new public sector buildings from 2018

So now we know where all the regulations and goals come from, the next post will get on to the changes for 2010.

mel starrs Regulation consultation, EPBD, Part L

I’ve read through the (non-technical) consultation which is out for Part L – comments to be back by 9 September.

The only item which piqued my interest was the clarification regarding multifoils.

3.1 BR 443 “Conventions for U-value calculations” sets out test methods and
calculation procedures for determining the thermal performance of building
elements that are considered appropriate for demonstrating compliance
with Part L of the Building Regulations. These test methods and calculation
procedures are based on the British and International standards that were
previously listed in earlier versions of the Approved Documents L.
3.2 In a judgment given in 2007, the High Court concluded that the Department
had not properly notified the European Commission, as required by the
Technical Standards Directive (98/34/EC), of the specific provisions contained
in paragraph 3.10.2 of BR 443 (March 2006 edition) for measuring the
thermal performance of multi-foil insulation products. Paragraph 3.10.2 was
declared unenforceable and remains so unless and until the correct notification
procedures under the Technical Standards Directive are completed.
3.3 That judgment did not affect other parts of BR 443 or the Approved
Documents L, and so the references in the Approved Documents L to BR 443
have continued to form part of the approved guidance on how compliance
with building regulations may be shown. Thus the general guidance in BR
443 for measuring thermal performance continues to apply to all building
elements, including multi-foil insulation products. This means that it remains
the case that only test results obtained from “hot-box” tests or tests that have
been agreed at a European level, such as those forming part of an agreed
European Technical Approval (ETA), carry a statutory presumption that they are
correct. However, the consequence of the judgment is that there is currently no
approved guidance which relates specifically to the measurement of thermal
performance of multi-foil products.

I’ll admit, this would not normally have been on my radar, except for the previous posts here, here and here from Mark Brinkley. Although the wording has now been cleared up, the performance of multifoils has still not been confirmed. It appears that paragraph 3.10.2 will eventually be reinstated:

3.5 The Department’s present view is that the appropriate methods for measuring
the thermal performance of materials and products are the hot-box test (which
is a British Standard test based on Standardised European Norms), or tests that
have been agreed at a European level. BR 443, including paragraph 3.10.2,
requires that measurement of thermal performance should be carried out using
such agreed tests. For this reason, the Department’s view is that the references
in the Approved Documents to BR 443, including paragraph 3.10.2, are
appropriate. It is for this reason that those references are retained in the draft
Approved Documents L that are the subject of this consultation.
3.6 This position has previously been set out in Communities and Local
Government Circular 06/2007, issued on 7 December 2007 as part of the
Department’s compliance with the judgment of the High Court.

I expect we’ll be hearing more from multifoil manufacturers between now and September then.

3.9 The Department is currently of the view, based both on international
scientific opinion and on scientific evidence commissioned and published by
it, that comparative testing does not provide accurate indications of thermal
performance.
3.10 The Department is however keen to know your views on this matter and
on whether generally the references to BR 443 as set out in the proposed
Approved Documents should be retained in the Approved Documents, and the
reasons for those views. If your views are that they should not be retained, the
Department would like to know your views on what should replace them.

The rest of the alterations are substantially cosmetic, but with a technical review due in 2010, and the last version 2 years old, we’ll have 3 copies of the regs within 2 or 3 years.

I’m in two minds about this.  On the one hand, it is better to have the entire document updated rather than having an errata addendum (such as the recent Code for Sustainable Homes which has the April 2008 Technical Guidance (pdf, 302 pp.) and the Addendum published 4 June 2008 (pdf, 16 pp), but on the other, with only cosmetic changes, it seems a waste of paper and a potential source of confusion.

mel starrs Uncategorized consultation, Part L

I was just perusing through the archives of BSJ looking for something else entirely, when I came across this debate from 2000 on the then proposed Part L. I found this paragraph to be particularly enlightening:

The clauses covering overheating criteria for naturally ventilated buildings puzzled more than one delegate. Oscar Faber’s Ant Wilson queried if it was wise to set a limit of 28°C for ten days over ten years at a solar gain of 15 W/m2. “What weather data is that based on, and what datasets should designers be using in future given that climate change may affect our ability to meet the criteria?,” he queried.

“My reaction is that it will make people put air conditioning in their buildings, which is much easier than doing the calculation,” predicted Ove Arup’s Chris Twinn.

Crystal ball gazing indeed. It’s a good read, especially with the hindsight of the past 8 years.  On a different topic (the NEF building in Milton Keynes), but from the same year, Chris Twinn advises the following with regards to BREEAM:

“there is no real payback on a BREEAM assessment for an owner-occupied building – the real benefit is for a landlord to attract tenants.”

Times have changed slightly there, I would say.

It was fun delving into the not so distant past, but not awfully conducive to actually doing what I was supposed to be doing.  At least I got a blog post out of it…

mel starrs Opinion Ant Wilson, BREEAM, Chris Twinn, Part L

Well, I hate to say I told you so but we’ve been here before.

Back in November 2002, I wrote an article for BSJ* pointing out the iniquities of the factor used for electricity in the old Part L.  Seems Code for Sustainable Homes still has a flawed factor included and a similar loophole to the one I was worried about then still exists.  That was over 5 years ago.  Yikes.

Let’s hope this time the error gets fixed…

*BTW, if you click through and read the article, can I point out that the typo in the first paragraph was entirely BSJ and not me.  It still rankles with me (and woe betide you if you send me an email with typos – I am liable to correct it and send it back to you.  Is this a character flaw?).

mel starrs Opinion BSJ, electricity, factors, Part L

I’m a bit very late in commenting on this, but the inevitable delay to HIPs has been announced.  The government’s phased roll requires HIPs for properties with four or more bedrooms from 1 August, followed by three-bed homes once 2,000 energy assessors have qualified, and all homes when 3,000 have qualified.

On 22 May NHER made this statement:

mel starrs Uncategorized accredited energy assessors, Energy, energy assessors, energy bills, energy performance certificates, European Union, Friends of the Earth, News, Part L, Royal Institution of Chartered Surveyors, Sustainability, United Kingdom