in this q a video we're going to answer the question how much light can i spill
onto a neighbouring property
this video relates to the garden lighting ideas video that we made in association with Ledvance
where we looked at some innovative products and ways that they could be used to illuminate
outdoor spaces for both practical and also for decorative uses so if you haven't already seen
that video then please check it out after watching this one along with the one that we
did on the Ledvance floodlight family but let's focus on this topic information on this subject
has been published by the institution of lighting professionals in their document The Reduction of
Obtrusive Light which is freely available as a pdf on their website ultimately the answer is
that it depends on the area that you're in the document defines five different environmental
zones in table two from E0 to E4 with E0 being the most sensitive to light pollution in areas where
astronomical observations are carried out or areas defined by unesco as starlight reserves
and E4 being urban areas like towns and cities where lots of night time activity
takes place so you can see that there's going to be vastly different requirements between somewhere
that has a protected status due to sensitivity to light and a city centre that is probably
already well illuminated for safety and the reduction of crime and this is borne out for us
in table three where we find some values for the maximum amount of light that are allowed to hit
a neighbouring property with particular focus on the windows of that property the table refers to
illumination in the vertical plane what does that mean well we can demonstrate by using a piece of
lighting calculation software like Dialux or Relux so let's say we've got a property here and i want
to add some outside lights to it and over here there's another property and i'm going to check
the value of light to make sure that it doesn't exceed the value stated in the ILP guidance note
so i can create a measuring surface that will check the value of light hitting it and give us
some key values for the light levels on here and by setting that up so it stands vertically on the
wall over here i can confirm these values now i could if i had concerns about the light level
hitting the windows on the building also make some smaller ones to get the values on those
exact areas so if i install this floodlight from the Ledvance floodlight family that we also made a
video on and just tweak the height of that and the angle that it's pointing at we can then run the
calculation and get the values off the software so you can see there that the light levels on this
surface are 1.54 lux at the most and 1.19 lux as an average now if i compare that to table 3 in the
ILP guidance note i can see what environmental zones it would be acceptable in just a quick
explanatory note on why there's two figures quoted for each environmental zone you'll see there that
there's a pre curfew and a post curfew value now that's not referring to a time when we all should
be off the streets and in bed in order to quell civil unrest it's merely an allotted time decided
on by the local planning authority to determine when artificial light levels should be reduced
so you can see that for an area designated as zone E0 there is simply no illumination from artificial
sources allowed which is fair enough as it could throw off astronomical observations or ruin the
view of those unesco starlight reserves if this property was in a zone designated E1 or a natural
area perhaps a relatively uninhabited rural area a national park or an area of outstanding natural
beauty then there's a maximum value of two lux allowed dropping to less than 0.1 lux post curfew
although that little asterisk there suggests that if we're talking about road lighting
the value could go up to one lux for a zone designated E2 which could be sparsely inhabited
rural areas villages or relatively dark outer suburban locations then we've got a value of
five lux pre-curfew and one looks post curfew for zone E3 which is well inhabited rural and
urban settlements small town centres of suburban locations there's a maximum of 10 lux pre curfew
and two lux post curfew and for an E4 zone which is town city centres with high levels
of night time activity we've got a value of 25 lux before the curfew and 5 lux after the curfew
so the maximum value on our calculation surface was 1.54 lux which means we're well within the
limits for zones E1 to E4 but couldn't apply this solution in zone E0 obviously
so there we go that's the guidance for maximum illumination levels onto neighbouring properties
and it's pretty straightforward obviously if you're not sure which of the environmental
zones the area that you're working in falls within then simply contact the local planning
authority and they'll be able to tell you if any of them apply now there are a couple of other
considerations that need to be made in terms of outside lighting and the intrusion of that light
onto other properties but we'll cover some of those in future videos of course as always we
want to hear from you do you factor intrusive light into your outside lighting installations
is it something that perhaps you'll think about more in the future please leave your
thoughts and questions in the comments section below and as always thank you very much for
watching