Posted by: @jamespa

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The consultants do not have right of access to your house and you haven't told us that you invited them in

They never asked me. If they did, I would have definitely let them in. The whole idea of the 'condition' seems to be based on 'assessment' at source and 'prediction' for my house.  

Posted by: @persephone

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@jamespa I really appreciate your responses. They are all very helpful. Could you please help me understand the 'condition' that my local council has imposed, as I do not understand what the assessor has achieved. 

.. an 'at-source' noise survey at the Air Source Heat Pump shall be undertaken and submitted to Fife Council for approval to demonstrate compliance with the predicted sound pressure levels at this source and the predicted sound pressure levels 1m from the first-floor façade of the adjacent residential property to the west. 

What is 'sound pressure' at source? Isn't it called 'sound power' when it is measured at source?

Thanks again for your time. 

I will try:

predicted = (in both cases) as predicted by the documents submitted for the planning application (not sure what they said, but whatever they said is the test of compliance.  Obviously a lower level is also acceptable, but not a higher level)

sound pressure vs sound power - sound power is the total sound energy emitted from the equipment measured (ie the sum over all directions).  Its measured in W (watts).  Its distance independent because it is measured over an entire sphere completely encircling the equipment.  Its also independent of what surfaces, reflectors etc there are, because it assumes no absorption.  Thus manufacturers can quote it meaningfully.

sound pressure is the pressure (force per unit area) that the sound emitted exerts at a specific point in space.  Its measured in pascals (Pa).  Other 'pressures' in everyday life are tyre pressure and atmospheric pressure.  Atmospheric pressure is usually given in millibars, a millibar is 100 Pa.   Tyre pressures are usually given in bar, which is 1000 millibars or 100,000 Pa. 

Sound pressure decreases (in free space) inversely with the square of distance from the source and is reduced by obstructions or attenuators (eg walls), but is increased by reflective surfaces, because they direct the sound energy which would have gone 'the other way' towards the listener.

Although they are different things, both sound pressure and sound power are typically quoted in dB (hence the enormous confusion) relative to a reference level.  For sound power the reference level is 1pW (10^-12 W) and for sound pressure its 20 μPa (10^-6 pascals)

dB is a logarithmic measure (10 log (pressure/reference pressure) or 10 log power/reference power)) so a sound power of 10pW is 10dB and a sound pressure of 200 μPa is also 10dB, but they are not the same thing.

To make matters even more complex sound pressure figures are often 'weighted'.  Thats the (A) you see in dB(A).  This weights the pressure in different frequency bands to take into account human perception, according to a standard formula.  There are several alternative weightings which are used for particular purposes.

MCS and others provide a spreadsheet from which you can estimate sound pressure in a given situation (combination of reflectors, obstructions and distance), given the sound power.  The Institute of Acoustics (which is presumably unbiassed) provides essentially the same spreadsheet (there are subtle differences but not material to your situation).  These spreadsheets are often used to estimate heat pump noise (pressure) at neighbouring properties and are the basis of the PD rules for heat pumps.  

I hope that helps, feel free to ask for further clarification.

Posted by: @jamespa

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These spreadsheets are often used to estimate heat pump noise (pressure) at neighbouring properties and are the basis of the PD rules for heat pumps.  

1- I believe MCS spreadsheet is designed to assess compliance with 42dBA for Permitted Developments. Is this the case for IOA spreadsheet? 

2- Can 42dBA be used as a planning 'condition' for an ASHP that is not a Permitted Development? If yes, what criteria should be met for assessing such installation (for instance criteria such as Q number in MCS)? 

Posted by: @jamespa

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not sure what they said, but whatever they said is the test of compliance

Who do you think can help me find out what it is? Because this is my main question: What has the assessment proved compliance with? 

Posted by: @persephone

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1- I believe MCS spreadsheet is designed to assess compliance with 42dBA for Permitted Developments. Is this the case for IOA spreadsheet? 

 

From what I recall The IoA spreadsheet doesn't bother with the last 4 steps in the MCS calculation.  These steps are entirely pointless as the pass/fail criterion can be obtained more simply by just testing whether the result at step 6 is 37dB(A) or less.  The pass/fail outcome is the same either way.

Posted by: @persephone

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2- Can 42dBA be used as a planning 'condition' for an ASHP that is not a Permitted Development? If yes, what criteria should be met for assessing such installation (for instance criteria such as Q number in MCS)? 

Its entirely up to your local planning authority to decide what criterion to use when they assess the application or impose a condition.   

Even if the LPA sets another 'pass' level the MCS/IoA spreadsheet can still be used to do the calculation*; step 6 of the MCS spreadsheet gives the expected sound pressure from the ASHP alone given the sound power, obstructions and reflective surfaces.  The IoA spreadsheet does exactly the same, but with slightly improved granularity as regards distance (the MCS spreadsheet relies on lookups of attenuation at discrete values of distance, the IoA one calculates the actual attenuation using the inverse square law).  The LPA isn't bound to accept this calculation however, they may insist on an actual measurement, although some might possibly try challenging this on the grounds that it imposes (they would argue) a burden which is disproportionate, particularly if its a clear cut case.

* in most cases.  The spreadsheet cant be used if the LPA set a level which includes background as opposed to a level due to the ASHP alone.  Normally LPAs base their condition on the latter. 

The MCS condition is 42dB including background which is assumed to be 40dB.  Why the calculation includes background at all escapes me, as this part of the calculation (steps 7-10) adds absolutely no value (but does add confusion).  The reason also escapes MCS - I asked them the reason and they told me that they didn't know and that the figure was mandated by MLUHC.  So I asked MLUHC where it came from and they haven't answered.  However the figure/assumption is equivalent to the Heat pump alone being a shade over 37dB (in the way the MCS spreadsheet does it (because it uses discrete values), its is equivalent to the heat pump alone being more than 37dB).

Posted by: @persephone

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Posted by: @jamespa

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not sure what they said, but whatever they said is the test of compliance

Who do you think can help me find out what it is? Because this is my main question: What has the assessment proved compliance with? 

It will be in the planning application or the supporting documents, which will be (or at least should be) on the LPA's planning portal.

Posted by: @toodles

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using wind shields on microphones

The image on page 4 of the assessment shows a simple microphone. 

Posted by: @jamespa

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It will be in the planning application or the supporting documents

1- The original application was supposed to be compliant with MCS.

2- The neighbour breached it and applied for a retrospective.

3- The retrospective was refused because " ... the Applicant has failed to submit ... a sufficiency of appropriate information to properly demonstrate and inform this Council as Planning Authority that the Air Source Heat Pump (ASHP), as adapted, has been properly and correctly installed within the application site together with the submission of on-site noise assessments all in compliance with MSC Planning Standards and in conformity with condition 2 annexed to the Decision Notice dated 19th November 2019 in relation to Planning Permission 19/02448/FULL. The application proposal is therefore considered to be contrary to Scottish Government Planning Advice Note 1/2011 - Planning and Noise; Policies 1, 10 and 11 of the Adopted FIFEplan 2017; and the Low Carbon Fife Supplementary Planning Guidance (adopted 2019) and is recommended for refusal. And ... " .

4- My neighbour then appealed, and the LRB imposed the 'condition' which we are talking about. And I have no idea what this 'condition' refers to. 

If anyone understands the 'condition', I really appreciate it if they could explain it.   

Posted by: @persephone

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If anyone understands the 'condition', I really appreciate it if they could explain it.

If you post the link to the planning application I'm happy to take a look.

This application has been approved and, as far as I am aware, as there are no third party rights of appeal against a planning decision in Scotland the only recourse currently available is to request a judicial review at the Court of Session.

@jamespa

This is the link to the original planning application

https://planning.fife.gov.uk/online/applicationDetails.do?activeTab=documents&keyVal=PWOS7KHFJUG00

This is the link where you will find the refusal letter and the LRB decision (reversing the refusal)

https://planning.fife.gov.uk/online/applicationDetails.do?activeTab=documents&keyVal=QWIFPJHFHWJ00  

@abernyte I just want to understand the criteria based on which the application was approved.