MCS consultation on amendments to PD rules

[JamesPa]

MCS is currently consulting on amendments to MCS-020 which defines the noise standard for permitted development  https://mcscertified.com/consultation-mcs-020-planning-standard-for-permitted-development-installations-of-air-source-heat-pumps/  They are putting forward a fair few sensible ideas and others which could be a nightmare.

 

I attach my response in case anyone thinks it might be interesting.  Obviously other may wish to respond directly to MCS with their own views.

 

 

Incidentally MCS-020 is also the reason why installations must be done by an MCS contractor to MCS standards if Permitted Development is to apply.  This is IMHO crazy - planning legislation is concerned with the external effect of development on others not the householder and the technical details of the installation (ie MCS standards/Installer) effects only the householder.  Thus this belongs in Building Regulations, consumer law, or the rules for getting Government Grants, but not in not planning law.  It should, IMHO, be removed leaving only the noise criterion to be defined in MCS-020. 

 

 

Response to MCS Consultation re MCS-020 - name redacted POST.pdf

[sharpener]

Thanks for taking the trouble to do this @JamesPa. It covers a lot of ground and I can't fault any of it. Except perhaps that the ENA already holds a database of HP (and other eqpt) approvals for the DNOs to use so that to my mind adding the noise levels would be a natural extension of it.

 

The "assessment location in free space" issue is a good one. I am assuming by "any part of the..." they intended to mean the window in question, but as with much else it was badly drafted.

 

The definition of habitable room is another. I listed a few in an earlier posting. Hallways and landings are arguably not rooms at all, but many so-called "rooms" are not noise-sensitive e.g. boot room, utility room, plant room, and some non-rooms are e.g. lounge, study, office, snug.

 

BTW the "1m from property boundary" rule belongs in a different discussion, but our prospective installers came again yesterday and I was alarmed that their TD firmly believed the minimum was 5m. Though he was quickly disabused by his colleague.

 

KUTGW

 

 

[Moonshine]

its going to be interesting which way this goes, the 42 dB criteria is a very blunt tool, especially in rural locations. The alternative proposed is a step in the right direction, however i know that even in 'urban' locations background noise levels can be very low and the 40 dB assumption will fall down.

 

The other instrument would be conducting a BS4142 assessment which is more in depth and costly as they go to site and measure the background noise levels. But these assessments are required by local authorities for plant not covered by PD. I have seen  councils ask for a BS4142 noise assessment for single external condenser. 

 

 

[JamesPa]

On 10/01/2024 at 16:15, Moonshine said:

its going to be interesting which way this goes, the 42 dB criteria is a very blunt tool, especially in rural locations. The alternative proposed is a step in the right direction, however i know that even in 'urban' locations background noise levels can be very low and the 40 dB assumption will fall down.

 

The other instrument would be conducting a BS4142 assessment which is more in depth and costly as they go to site and measure the background noise levels. But these assessments are required by local authorities for plant not covered by PD. I have seen  councils ask for a BS4142 noise assessment for single external condenser. 

 

 

I am not sure what the intention is with the background noise thing.  It could be that the 42dB(A) total limit stays in which case an ASHP in a quiet area could be noiser than in a noisy area (there is actually some logic to this).  Alternatively it could be that 42dB(A) applies to urban and a different limit (and different background) in rural.  It makes a big difference which they choose and it isnt specified.

 

I asked MCS in a separate communication where 42dB(A) came from and what the rationale was.  They said DLUHC, and that they didn't know what the rationale was!  This being the case I really don't see how they can propose changing anything, but they have

 

My LPA now asks for a BS4142 assessment for a domestic heat pump installation even if its only for heating and one external condenser.  This is ridiculous overkill and totally disproportionate IMHO, would they do that for a gas or oil flue?.  I got my application in just before they adopted this as a policy, but currently they want me to achieve 25dB(A) at the most affected assessment point, which is essentially impossible (and wholly unreasonable). 

 

If I find myself having to submit again I will probably fight the policy of requiring BS4142.  The law says that LPA document requirements must be both reasonable in proportion to the application and likely to have a material effect on the outcome.  It is certainly the latter but not the former, given that there is a simple spreadsheet available from MCS and from the Institute of Acoustics/Chartered Institute of Environmental health https://www.ioa.org.uk/heat-pump-briefing-notes-calculation-sheet-ioa-cieh  There is an external dispute resolution process if you think your LPA is unreasonably demanding documentation, and I think there would be a good chance that a case put to that would come out in favour of the applicant not the LPA particularly given what IofA says.

[JamesPa]

On 10/01/2024 at 16:00, sharpener said:

BTW the "1m from property boundary" rule belongs in a different discussion,

It does belong in a different discussion and its another crazy rule. 

 

For example If I were to cantilever my heat pump out from the garage flat roof, which is perfectly practical and actually quite convenient, the noise level at the nearest assessment point would be 29dB(A), because solid brick walls are in the way.  Its actually technically a good solution and, properly done, wouldn't look too out of place and is anyway hardly visible either from the public realm or the neighbours garden.  As it is the best I can do is 34dB(A) (still not good enough for my LPA) and that depends on an 'added' barrier which I guarantee wont be as good as a brick wall.  However the cantilever solution violates both the 1m boundary rule and the 1m from edge of flat roof rule. 

 

 

[Moonshine]

6 minutes ago, JamesPa said:

My LPA now asks for a BS4142 assessment for a domestic heat pump installation even if its only for heating and one external condenser.  This is ridiculous overkill and totally disproportionate IMHO, would they do that for a gas or oil flue?.  I got my application in just before they adopted this as a policy, but currently they want me to achieve 25dB(A) at the most affected assessment point, which is essentially impossible (and wholly unreasonable).

 

tbf ASHP's and condensers are a lot noisier than gas flues.

 

25 dBA is very low and its dependant on how far your nearest receptor is in achieving that.

[JamesPa]

7 minutes ago, Moonshine said:

 

tbf ASHP's and condensers are a lot noisier than gas flues.

 

25 dBA is very low and its dependant on how far your nearest receptor is in achieving that.

Yes, but not than oil boilers from what I am told.

 

We have to remember that an ASHP condenser is the new gas flue.  There is NO alternative mass market domestic heating solution which materially reduces carbon emissions.  Thus it has to be simple and cheap to get permission otherwise we cant fix climate change.  Its important to keep one eye on the objective!

 

25dBA is pointlessly low.  According to BS8233 a window closed or ajar attenuates by 15dB.  So the interior noise level corresponding to 25dB(A) at the nearest assessment point would be 10dB(A).  Also according to BS8233 an interior night time noise level of 30dB(A) is 'desirable' in a bedroom.  So 10dB(A) is a ridiculous target in relation to established methodology for assessing noise in buildings.

 

On 10/01/2024 at 16:00, sharpener said:

The "assessment location in free space" issue is a good one. I am assuming by "any part of the..." they intended to mean the window in question, but as with much else it was badly drafted.

This is yet another reason why the planning rules should be in planning law not written by a third party that doesn't have a legal mindset and is paid for by the industry.  Law needs to be precise not woolly, MCS wording is too often woolly. 

 

I had a 'woolliness' discussion with them over insulation to DHW pipework in retrofits.  Their rules, if read straightforwardly, simply don't make practical sense.  In the end they conceded that and came up with a circuitous way to interpret them so that they do make sense (which I have in writing in case of need).

 

Edited January 11 by JamesPa

[Beelbeebub]

Were there noise issues when we went from open and balanced flue boilers (almost silent) to the fan assisted room sealed ones? 

 

A condensing boiler is considerably noiser than a passive flue boiler that relies on boyancy to exhaust the flue gasses. 

 

Yes HPs are currently a bit nosier, but that can change. Noise tends to be related to power and coil area.  Power is driven by the house demand and is relatively inflexible once you're insulated. 

 

But unit size is more affected by planning. If we relaxed the need (both planning and just out general sense of aesthetics) for a smaller unit we could get quieter HPs. 

 

 

[HughF]

3 hours ago, Moonshine said:

 

tbf ASHP's and condensers are a lot noisier than gas flues.

 

25 dBA is very low and its dependant on how far your nearest receptor is in achieving that.

My neighbours boiler flue is considerably noisier than my heat pump….

[sharpener]

16 hours ago, JamesPa said:

According to BS8233 a window closed or ajar attenuates by 15dB

Am really surprised by that. IME a window even slightly ajar has little attenuation particularly for high frequencies, I would have guessed 15dB for closed but only 5dB for ajar.

 

Think how easy it is to detect when you have got a car window open just a crack.

 

Also no distinction between single and double glazing (though for best attenuation you need much wider spacing than the usual 4mm).

[saveasteading]

8 minutes ago, sharpener said:

window even slightly ajar has little attenuation 

Correct. Hence flanking sounds through tiny weaknesses in a wall construction, and the difference between a door closed or not quite.

[JamesPa]

13 minutes ago, sharpener said:

Am really surprised by that. IME a window even slightly ajar has little attenuation particularly for high frequencies, I would have guessed 15dB for closed but only 5dB for ajar.

 

Think how easy it is to detect when you have got a car window open just a crack.

 

Also no distinction between single and double glazing (though for best attenuation you need much wider spacing than the usual 4mm).

I was also surprised but it is what bs8233 says, at least on my reading.  Perhaps it means window in vent mode (ie nearly closed), or perhaps I'm misreading (but I don't think so).

[Kelvin]

If I open the vent on my Velux windows I can clearly hear our burn bubbling away 80m away. It’s a pleasant noise of course. Vents closed and it’s silent. I’m pretty sure I’ll be able to hear the ASHP too, certainly on the side closest to it despite it being on the East elevation 

[JamesPa]

18 minutes ago, JamesPa said:

I was also surprised but it is what bs8233 says, at least on my reading.  Perhaps it means window in vent mode (ie nearly closed), or perhaps I'm misreading (but I don't think so).

https://www.omegawestdocuments.com/media/documents/43/43.20 BS 82332014 Guidance on Sound Insulation and Noise Reduction for Buildings. London BSi.pdf at page 70 of the PDF (numbered 64 on the actual document).  Basically (as I read it) its saying that a solid facade with a window in will have an attenuation of ~15dB.  I guess the window alone is less, the solid bit more.  Elsewhere in the doc there is more detail but I have seen this used as a rule of thumb elsewhere. 

 

Thinking about it I would say that, experimentally, the background noise where I live, which daytime is 40-45dB(A) is fully attenuated to below 30dB(A) if I put the window in the master bedroom to either vent (slightly ajar) or closed, so Im prepared to believe that a facade with window is at least 10dB. 

 

This assumes I don't stand right next to the window inline with the opening.   If I do I would say that the attenuation is only 0-5dB).  In a car your ear is level with and only 30cm from the chink in the window, so you get a rather distorted situation relative to a typical domestic scenario).  At some point, with a window that is just slightly ajar, its like a solid but finite barrier, which we know does attenuate quite significantly.

 

 

Edited January 12 by JamesPa