MCs noise assessment

barker77

Hi does anyone know how to assess multiple barriers to calculate -db difference? The mcs calculator allows to pick a wall or fence but I have by between the heat pump and neighbour and I’d like to know if can combine or similar ? Also if needed can I include a third acoustic barrier around it and how could I factor the third barrier in? Cannot see this mentioned anywhere so grateful for advice! 

Alnat1

A reflective surface has to be within 1m of the heat pump to be included in the noise calculation. The ground will usually be 1st surface, unless wall mounted over 1m high. If it's placed by the house, then he wall behind is the 2nd surface. Any part of the building that sticks out at the side of the pump is the 3rd surface but installers will try and make it more than 1m away if possible.

Sound pressure increases with the number of reflective surfaces. Less surfaces means lower noise, any barriers increase sound. To put it simply, a surface is NOT an acoustic barrier, it is a sound amplifier.

matt_drummer

Alnat1 said:

A reflective surface has to be within 1m of the heat pump to be included in the noise calculation. The ground will usually be 1st surface, unless wall mounted over 1m high. If it's placed by the house, then he wall behind is the 2nd surface. Any part of the building that sticks out at the side of the pump is the 3rd surface but installers will try and make it more than 1m away if possible.

Sound pressure increases with the number of reflective surfaces. Less surfaces means lower noise, any barriers increase sound. To put it simply, a surface is NOT an acoustic barrier, it is a sound amplifier.

That's the Q value,

He's talking about an acoustic barrier between the heat pump and the assessment point.

You can only make a deduction for a maximum of one acoustic barrier for each assessment point.

barker77

Surely that can’t be right though as multiple barriers will affect the noise ? 

matt_drummer

Don't try and bring logic into it.

The rules are the rules as they are written.

With one full barrier, minus 10dB, with a partial barrier minus 5dB and with no barrier minus nothing.

That's it.

If you don't like it, or don't believe it, go and talk to the environmental protection office at your local authority.

Its them that count, not an internet forum!

matelodave

AFAIK the rules as written allow you to make an assessment without detailed investigation and without the cost of obtaining full planning permission and possibly additional measurements.

I guess you are liberty to apply for full planning permission and try to argue your case with the planning officer but that will probably cost you a lot of money and you may still not get an agreement if you cannot satisfy his requirements.

As said above, we may all have an opinion but it's not us that you have to satisfy .You could end up with an expensive problem if you try to invoke the might of the forum against the even greater might of a local authority planning department. Especially one which doesn't use common sense.

matt_drummer

Just ask the EPO at the local authority for advice.

Mine was really helpful, overly helpful, but passionate about noise and would in no way agree to an installation that did not comply with MCS 020, he actually thought it was too generous and 35dB or less at an assessment point was the only acceptable noise level.

If the installation does not satisfy the requirements of MCS 020 (even if you don't agree with it) then you should apply for planning permission.

Or you ignore it, at your own risk.

QrizB

I was reading an article on RevK's blog (he's an interesting chap, runs Andrews and Arnold the boutique ISP and occasionally appears on current affairs shows) and came across this post from 2018 detailing his planning permission / noise assessment saga with his local council.

Admittedly he has five separate mini split heat.pump units on a single 4-bed house on a suburban estate ...

https://www.revk.uk/2018/07/air-conditioning-at-home-planning.html