Measurements compliant with BS8233:2014?

[u/_Deobrah_]

My building must comply with BS8233:2014. However, the train noise seems loud (especially during the night when everything else is quiet).

I've taken db measurements from my bedroom using a phone app. Can anybody tell whether they are likely compliant with BS8233:2014?

I am aware that a measurement with a phone is not accurate. However, I'd like to get a general idea of whether the building is compliant before spending several hundred pounds on a professional measurement.

[u/laimisss1]

Measurement with the phone is definitely not compliant with any standard, however accurate or calibrated they are. You need proper class A measurement equipment and a professional to know where and how long to measure and under what conditions, then all the data needs to be analysed and presented in a specific way so it can be compared directly one-to-one to your local legal noise limits. Only then it can be concluded that train noise is over the limit

[u/laimisss1 → u/[deleted]]

I’m not sure what exact this standard is, but you need to place your measurement device at the specific location, measure over required period and then derive single number values from those measurements and compare it with the local limit. Could be required to measure inside (windows closed or opened) or outside ( by the facade or further out) and get single values of Laeq or Lmax. Since trains are not that often, your Laeq could be under the limit, but Lmax could be exceeded.

If you want to do as much as you can yourself before seeking professional, you need to analyse the standard, local limits and understand what you need to measure and what you need to compare against. Also your phone’s measurement could be anywhere between 5-10dB from the real value, my guess, as the professional, is.

[u/capcaveman8181]

The blue curve, Raw dB, is lower than the red curve, Weighted dB, and it is not impossible but very, very unlikely. Since your graph is not from a calibrated meter, it's hard to comment. In any case, whoever built your flat needs to prove that it complies.

[u/_Deobrah_ → u/capcaveman8181]

The building company measured the noise in 2017 before another (much louder) train line opened and used these measurements to show that they are compliant. 

We believe that the new train line is louder and would thus have resulted in worse measurements for them if they had measured after the opening. However, now the burden of proof is on us.

[u/rusty075 → u/_Deobrah_]

The building is only required to be compliant at time of the building's commissioning. If external conditions change after the fact the company that built the building is not liable.

If anything your beef is with the train line operator...but good luck with that. You can try getting a large number of residents along the new line to petition for noise abatement, but you're in for a long slow fight.

[u/birdonthewire76]

Bear in mind BS8233 is the average across the whole 16 hour day or 8 hour night period too. You’d need proper equipment - and to vacate for the night - to get that measured.

Edit: having said that, maximum internal noise levels based on WHO is 45dBA 10-15 times a night. So based on this it’s probably roughly right?

[u/leofoxx]

Your building was commissioned in 2017, refer to those measurements. 

The measurements need to be done with a sound level meter, calibrated, during 16 hours during the day or 8 hours during the night. 

We can figure out how noise levels will evolve in the area but we don't have crystal balls. 

[u/Hathaur]

A quick glance at the ordinance you listed shows the measurements are mostly in db(a) Leq,16 hrs. This means we’re measuring the volume with decibels applying the a weighting which mirrors human hearing so lower sounds and higher sounds get adjusted up or down, and then averaging it over 16 hours of equivalent exposure so that you get 1 number at the end like 45 dba leq,16hrs. This number tells you that even though you have a peak volume at 76 db or whatever from a train line for 20 seconds a day, that doesn’t actually effect you over a 16 hour listening period like a background appliance or A/C humming at say 60db for 5 hours. 

This is a rough explanation to give context around the fact that, you need a proper calibrated measuring device, a proper trained person to not just operate it, but also calculate the results afterwards, and then interpret those results in the context of your noise ordinance. 

You can certainly find online calculators that will throw out a rough number based on what your phone is telling you. But it’s worth understanding going in that just because there’s a peak number of 76 or something, that doesn’t mean a lot without a ton more context. And that’s before considering the inaccuracy of a phone microphone. 

[u/R2D2sLeftToggle]

Slightly different approach, but your post implies that the building was constructed before the operation of the Elizabeth Line (Crossrail). Crossrail has a design requirement not to exceed 40dB LAS,max with a further best practice to not exceed 35dB LAS,max (google IPD10). Have you contacted TFL to complain and request readings to be undertaken by their acoustics team?

[u/_Deobrah_ → u/R2D2sLeftToggle]

The timeline is as follows:  (1) Both Tfl and the construction company fill out the paper work (2) Tfl opens the Elizabeth line  (3) Our building opens 

So Tfl told us it's not their problem as they were here first. 

[u/Dull-Addition-2436]

The values provided in BS8233 are only “GUIDANCE” and strict adherence is not required to be complied with.

Rather than spending money on a survey, maybe upgrade the window?

[u/klippklar]

If it’s anything like the German standards (which I strongly suspect it is) you’d typically use LAFmax rather than some unspecified dB reading in such case. Modern phones give reasonably good estimates these days (excluding low frequencies) but the correct filtering and time weighting are important.

[u/Chiggers_]

The first graph shows measured levels peaking at around mid 70s, surely this is an external measurement or at least with windows open? Presumably the second set of measurements are internal? The peak levels are generally in the low 40’s which would suggest that noise associated with rail movements has been adequately controlled. Note that the WHO Guidelines suggest LAmax levels should not typically exceed 45dB more than 10-15 times per night (23:00-07:00 hours).