Zero Carbon Hub 2016 Task Force

[Mike Jacob]

Just received this briefing note re the proposed energy efficiency standard for 2016 new build:

“The role of heat recovery
The increasingly important role ventilation heat recovery can play in energy efficient homes with low air leakage is well known. However there are also concerns associated with installation and commissioning activities, occupant acceptance and indoor air quality, particularly if the correct maintenance regime is not followed.

What may at first appear to be an academic issue in terms of whether heat recovery is in or out of the scope of Energy Efficiency does in fact have a significant influence on just how advanced the minimum acceptable energy efficiency standard can be set for 2016. The Task Group’s view is that the standard should be set at a level which is achievable without the use of heat recovery, and that the benefit of heat recovery should not be taken into account when checking compliance with the standard. Any carbon benefit from the use of heat recovery would however aid achievement of the Carbon Compliance standard.”

[Mark Siddall]

I wonder if people said a similar concerns about user acceptance when central heating began to find its way into the main stream in early/ middle of the last century.

Mark

[Anonymous]

Who is “The Task Group” and have they published a rationale for their view?

[Mike Jacob]

Convened by the zero carbon hub to advise clg re definition of zero carbon. I'll post a link to their rationale tomorrow.

[Nick Grant]

Ironic that there is concern about health!!! So how are energy efficient houses to be ventilated?

MEV may be cheaper but not healthier. Is passive ventilation considered to be more robust and less likely to lead to humidity and air quality related problems?

I'm seriously considering retrofitting MVHR or controlled MEV to our house and wish we had designed to make that easier. Not to swap a few barrow loads of wood for slightly increased electricity use but to improve winter air quality without the need for almost continual manual adjustment of windows and vents as the weather changes.

oh dear

[Anonymous]

Mike, Many thanks for posting that briefing note.

In my opinion, it really exposes the lack of clear thinking

“the Housing Minister announced in July 2009 that the Carbon Compliance level would be set at 70% reduction in regulated CO2 emissions”

So that's a regular 'low energy' house then, not zero-carbon at all. And making the target so broad pretty much determines that nobody's going to try too hard to hit it right in the middle. So that's what they've done.

“The Task Group’s view is that the standard should be set at a level which is achievable without the use of heat recovery, and that the benefit of heat recovery should not be taken into account when checking compliance with the standard. Any carbon benefit from the use of heat recovery would however aid achievement of the Carbon Compliance standard.”

Rereading that part, which was in Mike's original post, it seems to be self-contradictory. “the benefit of heat recovery should not be taken into account when checking compliance with the standard” – I read that to mean that you have to ignore HR when calculating compliance. But then they say HR would “aid achievement of the Carbon Compliance standard” – I read that to mean that you can take account of HR when calculating compliance. So is it nonsensical, or is there another way to read it?

“The specifications were … modelled in SAP2009”. So the whole thing's not worth the electrons it's written with.

The Energy Efficiency Level section does two things. It confirms that they're aiming to define zero-carbon as meaning low-energy, and it graphically demonstrates the gulf between Passivhaus and the other specs they considered.

“The issue of mechanical ventilation with heat recovery was discussed at length in the context of occupant health and wellbeing. Other issues covered included natural daylight, quality of space and the potential implications of reduced air leakage in terms of build-up of VOCs, condensation and internal mould growth.”

I didn't see any other mention of MVHR or ventilation in general, and those two sentences just record that discussions occurred. So I'm still asking “have they published a rationale for their view?”

I've written to ask them for their rationale and for an explanation of the apparent contradiction.

Cheers, Dave

PS Chris, I'd agree that once you take the decision to have MV, the HR is a no-brainer. But to me it is driven the other way around. We need to reduce energy usage and ventilation is a significant heat loss. So we need HR; it's a given. The open question is whether there's any way to achieve it apart from MV? I'm not aware of any other way at present so therefore I believe in MVHR.

[Mark Siddall]

Definition of Zero Carbon:
To the best of my knowledge Europe is developing its own definition of zero carbon. We could see the UK definition getting redefined in the not to distant future.

AECB Standards:
Though none of the specifications in the “Table of ‘testing’ specifications” are based upon AECB Silver the document suggests that they “examined” the AECB Silver standard in their best practice survey. I hope that they adjusted the area metric to reflect the move from PHPP treated floor area to SAP net floor area (under SAPs methodology Silver would have an energy consumption that is 10-15% lower than 40 kWh/m2/yr – for all buildings including detached).
……Perhaps this discrepancy in floor area calculations also accounts for why the PassivHaus achieves 10 kWh/m2/yr…..

Also, by setting different standards for each building type designers are not encouraged to think are carefully about the surface area to volume.

Is design guidance all that’s needed – it is design and construction error that is causing buildings not to perform as expected.

kWh/m2/yr:
They seek views on whether kWh/m2/yr is a useful metric? Perhaps they need to look on the EPC. ….The HLP was a largely unfamiliar term until the CSH brought it to wider attention.

Any other thoughts /observations that people may wish to add?

Mark

[Anonymous]

I got a reply from the zero carbon hub:

Your e mail has been passed to me for consideration and I thank you for your comments. We are still developing the Energy Efficiency Specification and we are holding a series of events across the UK this week where we hope for further feedback. I hope you are aware of these and are able to attend. (Madeline, please send details)

We are receiving a series of queries from several sectors at this time and we will consider these, including your, with the Task Group following the events. Heat recovery has been hotly debated and still requires further consideration.

[Nick Grant]

The problem with the process is the same as with Code for Sustainable Homes etc. Stakeholder events (very self selecting) rather than reasoned technical papers open to peer review. That all happens after wrong decision has been made and the policy announced by politicians. Then can't loose face and have to start redefining things.

I'm just reading Irrationality by Stewart Sutherland and it explains very nicely how intelligent people can make such bad decisions despite a barrage of evidence. The examples given include Pearl Harbour and the Bridge at Arnheim but can add climate change for a latter edition.

Nick

[Mark Siddall]

Alan,
My understanding about the “apparent inconsistency” is the same as yours. The backstop value is focused upon the envelope only. MVHR will assist with reducing the carbon emissions, saving on bio-mass, wind turbines, PV or whatever.

My concern is how do you build to 3 m3/m3 @50pa? This is not a question about whether it is possible, what I mean is, how do you ensure that you don't build tighter by accident? If you achieve 1.5 m3/m3 @50pa do you go back and knock a few holes in the wall do address the “problems” arising from good construction? (I have visions of cat flap sized holes being “installed” in airtight homes – which will be plugged up by the building occupant sometime later due to thermal discomfort.)

Mark

[Anonymous]

(I have visions of cat flap sized holes being “installed” in airtight homes – which will be plugged up by the building occupant sometime later due to thermal discomfort.)

Mark, interesting point. You're describing current practice. They're called trickle vents! Or in the case of a friend of mine, what I guess to be a 150 mm diameter hole in the wall of each room instead of trickle vents. And much better, since easier to plug up, as you say 🙂 Opening the windows is still available to ventilate.

Thanks to you and Alan for clearing up my misunderstanding.

Nick, Exactly! (That's as much as I can trust myself to say)

[Mark Siddall]

Dave,
To my mind this issue is not like trickle vents, it's subtly different – though I appreciate what you are suggesting. As I see it the Hub suggest that 3 m3/m2 @50pa is, for reasons of IAQ, the acceptable limit to airtightness. So on this basis it is reasonable to expect that accidental improvements upon this standard will require “remediation” if IAQ is to be maintained i.e. additional holes/ air bricks (can't readily add new trickle vents as the windows are in already). This contrasts with the stance of the current UK modus operandi which, because 10 m3/m2 @50pa is so sloppy, means we're not required to worry about the addition of compensatory air leakage – presumably because this is not believed to make IAQ appreciably worse. So as I see it, and despite certain similarities, bashing additional holes into an airtight home is quite different to relying upon trickle vents – even thought they are both means of introducing controlled ventilation.

Anyway, enough of trying to understand the implications of this perverse logic, as Alan says, there are BRE studies that show IAQ is already compromised by poor quality, trickle vent controlled, natural ventilation and substandard MEV.

Mark

[Mark Siddall]

Nick,
I completely agree regarding the concerns about the potential damage to the building fabric. Dr Feist is not alone, similar concerns have also been observed in Canada, as noted in the Green Building Mag article on thermal bypass:

http://www.greenbuildingpress.co.uk/product_details.php?category_id=9&item_id=174

For the thread on bypass see:
https://aecb.net/forum/index.php?topic=1962.msg8180#new

Mark

[David Olivier]

You almost certainly either need continuous MEV, with bldg. depressurised, or continuous MVHR, with balanced pressures. In buildings that are allegedly “ventilated” by unreliable means, one can sometimes observe condensation on the air bricks. These means to “naturally ventilate” don't work and we seem to be in a debate on a par with where Sweden was in 1965-70; but the UK has almost de facto abolished building research so it's difficult to point to authoritative studies here to convince people.

It isn't true that MVHR always saves energy. MEV offsets the background air infiltration, MVHR doesn't. One has to do the sums. At 3 m/h the case is extremely marginal especially taking cost/resources into account. The sums concerning the physics were done inter alia in Sweden 30 yrs ago and by Bob Lowe when at LMU about 5 yrs ago – the tighter the building the more the saving from MVHR versus MEV

If a building is heated by CHP or a heat pump there are ways to refine MEV which aren't an option with MVHR. On this please await the Wates/Orchard Partners entry to the TSB competition or come along to the Roupell Park condensing CHP visit on 12 Nov (register with Sally).

D.

[Mike Jacob]

They said in today's consultation event that the aecb had been actively involved in the hub's work and reasoning. Anyone know if that is true? I haven't got that impression from the responses to this thread..

[Mike Jacob]

what a great response nick – you are not wrong in my view

[SimmondsMills]

nor mine

[Mark Siddall]

Ditto

[Anonymous]

Excellent summary, Nick.

I don't think it's necessary to invoke a conspiracy but I think that with the way things are set up, the self-interest of the players drives many of them in a similar direction.

As well as the zero carbon standard, there's also the microgeneration standard to think about at present. It's probably a lost cause to ask why a heat pump is classed as microgeneration but there is one issue it might be worth thinking about.

At present, I understand the plan is that in order to receive FIT payments, both the installation and equipment will need to be MCS-certified. It's not clear to me why this should be so. There seem to be two relevant issues: safety and accounting/auditing. For electricity generation at any rate, all that's needed to be sure of accurate accounting is that the metering is accredited; that can be done in a similar way to existing meter regulation. For safety, all that's needed is that the installation is checked to comply with regulations, as is done at present.

It seems to me that a requirement for MCS certification of installers is an unnecessary restraint of trade that will affect small traders and DIY in particular. Requiring MCS certification of products is also an unnecessary restraint of trade but more importantly it is an inhibitor of innovation that is likely to slow development and cost reduction.

For thermal systems – both generation and conservation (i.e. HP) – it's more complicated to measure how much energy is involved so it may be necessary to certify more than a single meter.

But it seems to me that the whole system would work better with less regulation. Rules only where necessary.

[Nick Grant]

Thanks for the kind words.

Was just browsing The usable Buildings Trust website for one liners and stumbled upon:

“It is easier to introduce new complications than resolve the old ones.” Neal Stephenson

How is that Zero Carbon definition coming along??

more at:

http://tr.im/Dyas

[Anonymous]

The more regulations that there are the more money the regulatory bodies make.
It is a conspiracy, a conspiracy to make money!

[SimmondsMills]

So – now the ZCH min. energy efficiency standard has been announced – prematurely in AECB's view, and we have some serious problems with it, although it is struggling with some real and challenging issues (well challenging to the UK anyway). Watch this space….

[Author]

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